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A Review of Metal Recovery from Spent Petroleum Catalysts and Ash
Abstract
With the increase in environmental awareness, the disposal of any form of hazardous waste has become a great concern for the industrial sector. Spent catalysts contribute to a significant amount of the solid waste generated by the petrochemical and petroleum refining industry. Hydro-cracking and hydrodesulfurization (HDS) catalysts are extensively used in the petroleum refining and petrochemical industries. The catalysts used in the refining processes lose their effectiveness over time. When the activity of catalysts decline below the acceptable level, they are usually regenerated and reused but regeneration is not possible every time. Recycling of some industrial waste containing base metals (such as V, Ni, Co, Mo) is estimated as an economical opportunity in the exploitation of these wastes. Alkali roasted catalysts can be leached in water to get the Mo and V in solution (in which temperature plays an important role during leaching). Several techniques are possible to separate the different metals, among those selective precipitation and solvent extraction are the most used. Pyrometallurgical treatment and bio-hydrometallurgical leaching were also proposed in the scientific literature but up to now they did not have any industrial application. An overview on patented and commercial processes was also presented.
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... Similar to lead, copper, and tin production, antimony is mainly extracted by pyrometallurgical methods. Hydrometallurgical routes, which are typically used for low-grade ores (<5% Sb) [32,33] and to minimize losses of PMs, can be classified into two groups of alkaline leaching and acid leaching, followed by the electrodeposition of metallic antimony at the cathode or hydrolysis with NaOH or NaH 4 OH to produce Sb 2 O 3 [32,[34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. An example is a process used at Sunshine Mining Co (between Kellogg and Wallace, ID, USA) [49]. ...
... By repeated distillation, Min-Chin [84] and Ivanov and Papirov [87] obtained a product containing 99.999% antimony, although in rather low yield. However, a more common practice is use of soda and oxygen or sodium hydroxide to form sodium arsenate and remove it from the melt, Equations (31)- (34), in a fire refining process: 2As + 3Na 2 CO 3 + 2.5O 2 (g) = 2Na 3 AsO 4 + 3CO 2 (g) (31) 2As + 3Na 2 CO 3 + 1.5O 2 (g) = 2Na 3 AsO 3 + 3CO 2 (g) (32) 2As + 4NaOH + 2O 2 (g) = 2Na 2 ASO 3 + 2H 2 O ...
... By repeated distillation, Min-Chin [84] and Ivanov and Papirov [87] obtained a product containing 99.999% antimony, although in rather low yield. However, a more common practice is use of soda and oxygen or sodium hydroxide to form sodium arsenate and remove it from the melt, Equations (31)- (34), in a fire refining process: 2 + 3 2 3 + 2.5 2 ( ) = 2 3 4 + 3 2 ( ) ...
Antimony is classified as a critical/strategic metal. Its primary production is predominated by China via pyrometallurgical routes such as volatilization roasting—reduction smelting or direct reduction smelting. The performance of most of the pyro-processes is very sensitive to concentrate type and grade. Therefore, technology selection for a greenfield plant is a significant and delicate task to maximize the recovery rate of antimony and subsequently precious metals (PMs), mainly gold, from the concentrates. The current paper reviews the conventional pyrometallurgical processes and technologies that have been practiced for the treatment of antimony concentrates. The blast furnace is the most commonly used technology, mainly because of its adaptability to different feeds and grades and a high recovery rate. In addition, several other more environmentally friendly pyrometallurgical routes, that were recently developed, are reviewed but these are still at laboratory- or pilot-scales. For example, decarbonization of antimony production through the replacement of carbonaceous reductants with hydrogen seems to be feasible, although the process is still at its infancy, and further research and development are necessary for its commercialization. At the end, available refining methods for removal of the most important impurities including arsenic, sulfur, lead, iron, and copper from crude antimony are discussed.
... Spent catalysts from the petrochemical and petroleum refining industries contribute significantly to the amount of solid waste disposed of in landfill [13]. Spent non-regenerable heterogeneous catalysts containing Pd, Pt, Ni, Mo, Co, W, V, etc. are discarded as solid wastes from the hydrotreating plants of petroleum refining, fine chemicals and petrochemical industries [14]. ...
... Figure 3 shows the methodically stages involved in the recovery of metals and supports from spent catalyst and industrial waste. A detailed review on the techniques of recovering metals from spent catalysts from petroleum refining industries has been reported elsewhere [13]. Likewise, a review on methodologies to recover PGMs and rhenium (Re) from electronic waste and spent catalysts has been reported in the literature [16]. ...
... The methods can be classified into hydrometallurgical (i.e. the use of aqueous solvents to recover catalytic materials), pyrometallurgical (i.e. thermal application to recover metals), electrochemical and biohydrometallurgical (i.e. the use of biological process such as microorganism to recover materials) technologies [13,16]. However, the challenges with hydrometallurgical and pyrometallurgical methods include costly processes, large amounts of solvents required, disposal of the solvents that could create secondary environmental pollution and energy intensive [33]. ...
The future of catalyst will be controlled by sustainable environment and renewability. Presently, most of the catalytic materials are sourced from finite geological deposits. Most of the resources rely up on for catalyst manufacture are dwindling and the accumulation of waste and spent catalyst poses a serious environmental problem and economic sabotage. By recovering catalyst from waste and reclamation of active metals from spent catalyst, the dependence on natural resources that are unsustainable will be reduced, likewise the quantity of materials going to landfill. This work introduces circular economic thinking into catalysis and waste and resource management. The utilisation of industrial waste, waste shells (e.g. seashells and eggshells) and animal bones as a source of catalyst not only provides an economic and environmental protection benefits, but also promotes proper waste management strategy and circular economy. This review stimulates and provides a roadmap for the transition of catalytic science and manufacturing into a circular economy. The major contribution of this work is in the design of green and renewable catalyst from waste materials, and reviews their applications in organic synthesis, hydrogen production from waster-gas-shift reaction and gasification of biomass, biodiesel production, oxidation reactions, selective hydrogenation and pollutant degradation.
... According to different sources, EoL hydroprocessing catalysts can be recycled for Co recovery, or downcycled for steel production (National Research Council, 1983;Marafi and Stanislaus, 2008;Akcil et al., 2015). Catalysts used in the plastic industry are indirectly recycled to the same process, due to the recycling of PET bottles (Committee of PET Manufacturers in Europe, 2018). ...
... While the metal is not dissipated into the environment, it is dissipated in the technosphere, as it is generally unfeasible to recover it from the large-magnitude stream (Buchert et al., 2009;Graedel et al., 2011;Zimmermann and Gößling-Reisemann, 2013;Zimmermann, 2017). Co is usually nonfunctionally recycled in the production of stainless steel (Akcil et al., 2015;European Commission, 2017d). ...
... The W-Co powder is used in the manufacturing of new hard metals (Katiyar et al., 2014;Freemantle and Sacks, 2015;Kurylak et al., 2016). In the case of downcycling, it was considered that the recovered metallic stream is used in the production of stainless steel (Akcil et al., 2015;European Commission, Chapter 4 2017c). The values of matrix B and D are available in SI. ...
... Spent catalysts have good potential for extracting valuable elements (Ni, V, Mo, Co, etc.) due to depletion of primary resources mines, increasing vanadium demand by the industry, and landfilling environmental problems as hazardous wastes [19,36,37]. The hydrometallurgical (acid or alkali leaching and solvent extraction processes) in the combination of roasting and bio-hydrometallurgical (bacterial leaching based on the ability of microorganisms, bacteria, or fungi as leaching reagents) methods have been reported for the extraction of vanadium from the spent catalysts at room temperature and atmospheric pressure [38][39][40][41][42]. However, further studies are needed to develop a process that considers low waste generation, safe waste disposal, low costs, and other economic, and environmental benefits [19,42]. ...
... The hydrometallurgical (acid or alkali leaching and solvent extraction processes) in the combination of roasting and bio-hydrometallurgical (bacterial leaching based on the ability of microorganisms, bacteria, or fungi as leaching reagents) methods have been reported for the extraction of vanadium from the spent catalysts at room temperature and atmospheric pressure [38][39][40][41][42]. However, further studies are needed to develop a process that considers low waste generation, safe waste disposal, low costs, and other economic, and environmental benefits [19,42]. ...
... These processes include leaching, solvent extraction, and precipitation. On the other hand, the pyrometallurgical process (the vanadium is mainly trivalent) like roasting has been used in combination with the hydrometallurgical process [42,112]. Besides vanadium, other valuable metals (such as molybdenum (Mo), cobalt (Co), and nickel (Ni)) can be recovered during the treatment of spent petroleum catalysts [18]. ...
Vanadium is a strategic metal and its compounds are widely used in industry. Vanadium pentoxide (V2O5) is one of the important compounds of vanadium, which is mainly extracted from titanomagnetite, phosphate rocks, uranium-vanadium deposits, oil residues, and spent catalysts. The main steps of vanadium extraction from its sources include salt roasting, leaching, purification, and precipitation of vanadium compounds. In the hydrometallurgical method, first, the vanadium is converted to a water-soluble salt by roasting, and then the hot water is used to leach out the salt-roasted product and the leach liquor is purified by chemical precipitation, solvent extraction, or ion exchange processes to remove impurities. Then, a red cake precipitates from an aqueous solution by adjusting the conditions. To provide high pure vanadium pentoxide, it is necessary to treat the filtered red cake in ammonia solution. So, ammonium metavanadate (AMV) is precipitated, calcined, and flaked to vanadium pentoxide. In the pyrometallurgical method, vanadium-containing concentrate is smelted, and by forming titanium-containing slag and molten pig iron, oxygen is blown into pig iron in a converter or shaking ladles, and vanadium is oxidized to produce vanadium-rich slag. In the next step, the slag is roasted and treated by the hydrometallurgical process. In this paper, the industrial processes and novel developed methods are reviewed for the extraction of vanadium pentoxide.
... The two main routes are pyrometallurgy and hydrometallurgy. Marafi et al., Furimsky, and Zeng and Cheng provide comprehensive reviews on this topic (Marafi et al., 2017;Furimsky, 1996;Zeng and Yong Cheng, 2009;Akcil et al., 2015), and details of commercial processes are provided by Marafi et al., Akcil et al., Llanos and Deering, and Berrebi et al. (Marafi et al., 2017;Berrebi et al., 1993;Akcil et al., 2015;Llanos and Deering, 1998). Pyrometallurgy routes are used mainly to produce metal alloys while hydrometallurgy routes are more suitable to obtain vanadium oxides. ...
... The two main routes are pyrometallurgy and hydrometallurgy. Marafi et al., Furimsky, and Zeng and Cheng provide comprehensive reviews on this topic (Marafi et al., 2017;Furimsky, 1996;Zeng and Yong Cheng, 2009;Akcil et al., 2015), and details of commercial processes are provided by Marafi et al., Akcil et al., Llanos and Deering, and Berrebi et al. (Marafi et al., 2017;Berrebi et al., 1993;Akcil et al., 2015;Llanos and Deering, 1998). Pyrometallurgy routes are used mainly to produce metal alloys while hydrometallurgy routes are more suitable to obtain vanadium oxides. ...
... For the base case scenario, a recovery plant with a capacity of 30,000 tonnes of spent catalyst per year (annual output of 5,400 t V 2 O 5 and 1,720 t MoO 3 ) was considered. This is a typical capacity of existing commercial plants (Akcil et al., 2015); however, the economies of scale were investigated by changing the plant capacity from 2,000 to 50,000 t/y. Thus, plants with the capacity to process spent catalyst from upgraders located in Alberta were included in the analysis. ...
Spent catalyst from bitumen upgrading contains a substantial amount of vanadium. Recovering this vanadium can contribute to meeting the global demand. However, there are no studies on the economic feasibility of vanadium recovery plants, which is critical for decision makers. In this research, a techno-economic assessment of a vanadium recovery process was performed to bridge that gap. Data intensive process models were developed to understand the mass and energy balances of the vanadium recovery process. Capital and operating costs were estimated from material and energy balances. The recovery cost of vanadium was estimated using the developed
techno-economic models, including the revenue for selling the co-products and by-products of the process. The economies of the scale and the effect of co-product and by-product selling price on the vanadium recovery cost were also studied. We found that for a plant capacity of 30,000 tonnes of spent catalyst per year, the vanadium
recovery cost is $9.89/kg V2O5. For a market price of $12.00/kg V2O5, the minimum profitable capacity is about 22,400 tonnes of spent catalyst per year, and molybdenum trioxide is the co-product whose selling price has the most influence on the vanadium recovery cost. The results show that for spent catalyst generated in bitumen
upgrading operations, the recovery of vanadium is potentially profitable considering the current vanadium market price. The developed information is useful for the decision makers in making investment decisions and policy formulation.
... A large amount of inorganic solid catalysts is used in oil refineries to accelerate chemical reactions in various processes known as thermo-chemical catalytic processes [1]. These catalysts are used to remove sulfur, nitrogen and other metals in the crude oil structure during the petroleum refining process. ...
... The amount of catalyst consumed by the oil industry all over the world is estimated to be 150 × 10 3 −170 × 10 3 per year [5]. The spent catalysts in petroleum refineries constitute only 4% of the total refinery wastes and it is classified as a hazardous waste to the environment and human health by various organizations [1,6]. Therefore, the valorization or disposal of the spent catalysts containing various metals are highly important. ...
... In the literature, there are studies conducted in the presence of different acid and alkali solvents to recover valuable metals from the spent catalysts; mixture of H 2 SO 4 , HNO 3 and HCl solutions [18,19] [22]. In addition, there are also studies in which the roasting process was applied followed by leaching process [1,3,4,23]. However, there is no study in the presence of sodium persulfate (Na 2 S 2 O 8 ) leaching agent for the recovery of valuable metals from the spent catalyst after roasting pre-treatment. ...
The spent hydrodesulphurization (HDS) catalyst is an important secondary source for Ni, Mo, Co and Al metals. The high yield recovery of these metals is quite difficult due to the carbon accumulated on the catalyst surface and the stability of the metal oxides. Therefore, the leaching process in the presence of sodium persulfate (Na2S2O8) was carried out after the roasting pre-treatment to remove the carbon from the spent HDS catalyst structure and convert the metal oxides to the soluble form in this study. The optimum experimental conditions were determined as roasting temperature, 500 °C; roasting time, 120 min.; particle size, +75–30 μm; liquid/solid ratio, 12.5 ml/g; Na2S2O8 concentration, 0.4 M; leaching temperature, 50 °C; leaching time, 90 min and stirring speed, 400 r/min. Recovery of Mo (89.8%), Co (86.5%) and Ni (81.2%) from leach solution were achieved by precipitation method. The liquid film diffusion control mechanism best represents the proposed leaching process. On the other hand, the magnitude of Ea values (<20 kJ/mol) for Mo, Co, Ni and Al metals indicates that the leaching process is controlled by liquid film diffusion mechanism.
... Among all industrial applications, Mo catalyst is widely used in petroleum desulphurisation to minimize sulphur dioxide emissions from fuel combustion [2], [3]. Therefore catalysts not only enable for economical fuel purification, but also contribute to environmental safety through low sulphur emissions [3], [4]. ...
... The most vital spent catalysts containing valuable metals are Mo, Co, Ni, V, Al from secondary resources [5], [6]. However, aligned with its frequent use, catalysts have a tendency to quickly deactivate [4]. As a result, a large number of deactive HDS catalysts become spent catalysts because they contain toxic elements in the catalyst such as V, Ni, Mo, and Co, and can be easily leached out with water causing secondary pollution, therefore it needs to be processed in order to meet environmental regulations [7]. ...
... Fluid catalytic cracking (FCC) is one of the major secondary operations for refining crude oil. FCC catalysts are widely used in the conversion of heavy feedstocks into lighter, more valuable products such as liquefied petroleum gases (LPG), cracked naphtha, and diesel oil [1][2][3]. In China, about 70% of gasoline and 33% of diesel are produced using this process [4,5]. ...
... Currently, there are many studies on FCC spent catalysts, but most of them focus on the comprehensive utilization of FCC spent catalysts, such as extracting metals [1,[10][11][12], adsorbent material [13,14], or cement raw material [15][16][17][18]. In terms of the hazardous characteristics of FCC spent catalysts, the main focus is on the morphology of the heavy metals nickel and vanadium. ...
Fluid catalytic cracking (FCC) spent catalysts are the most common catalysts produced by the petroleum refining industry in China. The National Hazardous Waste List (2016 edition) lists FCC spent catalysts as hazardous waste, but this listing is very controversial in the petroleum refining industry. This study collects samples of waste catalysts from seven domestic catalytic cracking units without antimony-based passivation agents and identifies their hazardous characteristics. FCC spent catalysts do not have the characteristics of flammability, corrosiveness, reactivity, or infectivity. Based on our analysis of the components and production process of the FCC spent catalysts, we focused on the hazardous characteristic of toxicity. Our results show that the leaching toxicity of the heavy metal pollutants nickel, copper, lead, and zinc in the FCC spent catalyst samples did not exceed the hazardous waste identification standards. Assuming that the standards for antimony and vanadium leachate are 100 times higher than that of the surface water and groundwater environmental quality standards, the leaching concentration of antimony and vanadium in the FCC spent catalyst of the G set of installations exceeds the standard, which may affect the environmental quality of surface water or groundwater. The quantities of toxic substances in all spent FCC catalysts, except those from G2, does not exceed the standard. The acute toxicity of FCC spent catalysts in all installations does not exceed the standard. Therefore, we exclude “waste catalysts from catalytic cracking units without antimony-based passivating agent passivation nickel agent” from the “National Hazardous Waste List.”
... The construction industry provides a possibility to utilise FCCCw in the manufacture of cement-based materials [49]. The main constituents of the FCCCw [50,51] are an aluminosilicate faujasite-type zeolite (with a highly porous crystalline microstructure), an essentially amorphous alumina as catalytic active phases and a clay. These spent catalysts were found to be highly pozzolanic [52][53][54][55][56][57][58][59]. ...
This paper describes research on the synergistic effect of nano–SiO2 (NS) and spent fluid catalytic cracking catalyst (FCCCw) in cement pastes’ pozzolanicity. Binary and ternary blended cement pastes containing 0.02% of NS and 5–20% of FCCCw were investigated. Hydration at early age followed using semi-adiabatic calorimetry. The macroscale properties were assessed by measuring density, ultrasonic pulse velocity and compressive strength. The microstructures were analysed by scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. The results are consistent among the different techniques and materials’ levels and show that a small NS content promotes a marked synergistic enhancement of the pozzolanic reaction.
... Currently, most of the SFCC catalyst was disposed in landfills, which can not only lead to the waste of valuable constitutes but also induce environmental risk [20,21]. Several investigations [22][23][24] into the application of SFCC have been reported, including recycling of rare earth metals or aluminum and synthesis of geopolymer, zeolite Y, mortar, and other composite materials. Very few papers, however, focus on that SFCC was used as a fluxing material to optimize the rheological properties of smelting slag in the metal smelting-collection process for platinum recovery from SAC. ...
A novel method of smelting of mixture of spent automotive catalyst (SAC) and spent fluid catalytic cracking catalyst (SFCC) to recover platinum and prepare glass slag was investigated. Compared to other metals collection processes for single hazardous waste solid, this method reduced the amount of fluxing materials addition and increased the processing types of hazardous solid waste simultaneously. The optimum SFCC addition, iron collector addition, Na2B2O4•10H2O addition, CaO/SiO2 mass ratio, temperature, and holding time for platinum recovery were 20 wt%, 11 wt%, 16 wt%, 0.6, 1550-1600 °C, and 60 min, respectively. In this proposed combined process, more than 98% of platinum is efficiently recovered from SAC. Meanwhile, the concentration of platinum in glass slag was less than 7 g/t. The leaching characteristics of heavy metals in slag confirmed the obtained glass slag is a non-hazardous slag due to the low leaching rate of heavy metal ions. This article proposed an effective and environmentally friendly method for recovery of platinum from SAC via a combined smelting process.
... More than 100,000 tons of spent hydrodesulphurization catalysts are produced every year, which usually contain the valuable elements V, Mo, Ni, and Co [72]. Vanadium in spent catalyst is present in the form of sulfide (V 2 S 3 or V 3 S 4 ) [73]. Oxidation roasting of spent catalyst and subsequent NaCl/H 2 O roasting of oxide were proposed by Biswas et al. [74], and 81.9% of V was extracted. ...
Vanadium as a rare element has a wide range of applications in iron and steel production, vanadium flow batteries, catalysts, etc. In 2018, the world’s total vanadium output calculated in the form of metal vanadium was 91,844 t. The raw materials for the production of vanadium products mainly include vanadium-titanium magnetite, vanadium slag, stone coal, petroleum coke, fly ash, and spent catalysts, etc. Chlorinated metallurgy has a wide range of applications in the treatment of ore, slag, solid wastes, etc. Chlorinating agent plays an important role in chlorination metallurgy, which is divided into solid (NaCl, KCl, CaCl2, AlCl3, FeCl2, FeCl3, MgCl2, NH4Cl, NaClO, and NaClO3) and gas (Cl2, HCl, and CCl4). The chlorination of vanadium oxides (V2O3 and V2O5) by different chlorinating agents was investigated from the thermodynamics. Meanwhile, this paper summarizes the research progress of chlorination in the treatment of vanadium-containing materials. This paper has important reference significance for further adopting the chlorination method to treat vanadium-containing raw materials.
... However, because of the high molybdenum content (4-12%), the spent HDS catalysts are also evaluated as an important secondary molybdenum resource. With the depletion of high-grade molybdenum minerals and the increasing demand for molybdenum, the recovery of molybdenum from HDS spent catalysts has received more and more attention [3,4]. ...
Molybdenum bearing spent hydrodesulphurization (HDS) catalyst is an important secondary resource. In the present research, the extraction of molybdenum from the roasted spent HDS catalyst was investigated by pressure alkaline leaching using NaOH and Na2CO3, respectively. The process of pressure leaching using Na2CO3 solution was characterized by high extraction of molybdenum, lower aluminum leaching, as well as low cost of mineral decomposition, which make it become the better option. For the process of pressure leaching using Na2CO3, under the optimum conditions of 20 wt% Na2CO3 addition, leaching at 170 °C for 30 min with a liquid/solid ratio of 2 mL/g, the leaching of molybdenum reached 95.4%, and the leaching of aluminum was only 0.7%.Graphical Abstract
... It is estimated that vanadium forms 0.019% of the Earth's crust, being its eighteenth most abundant element [4]. Nevertheless, the great number of industrial needs and the increasing consumption of this element, on one hand, and the depletion of the corresponding mineral resources, on the other, require the development of efficient methods for the recovery of vanadium from second-hand sources and industrial waste [5]. Moreover, vanadium is considered as a serious contaminant [6], similarly to mercury, lead, and arsenic [7]. ...
A polymer inclusion membrane (PIM) composed of 50 wt% base polymer poly(vinylidenefluoride-co-hexafluoropropylene), 40 wt% extractant Aliquat® 336, and 10 wt% dibutyl phthalate as plasticizer/modifier provided the efficient extraction of vanadium(V) (initial concentration 50 mg L−1) from 0.1 M sulfate solutions (pH 2.5). The average mass and thickness of the PIMs (diameter 3.5 cm) were 0.057 g and 46 μm, respectively. It was suggested that V(V) was extracted as VO2SO4− via an anion exchange mechanism. The maximum PIM capacity was estimated to be ~56 mg of V(V)/g for the PIM. Quantitative back-extraction was achieved with a 50 mL solution of 6 M H2SO4/1 v/v% of H2O2. It was assumed that the back-extraction process involved the oxidation of VO2+ to VO(O2)+ by H2O2. The newly developed PIM, with the optimized composition mentioned above, exhibited an excellent selectivity for V(V) in the presence of metallic species present in digests of spent alumina hydrodesulfurization catalysts. Co-extraction of Mo(VI) with V(V) was eliminated by its selective extraction at pH 1.1. Characterization of the optimized PIM was performed by contact angle measurements, atomic-force microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis/derivatives thermogravimetric analysis and stress–strain measurements. Replacement of dibutyl phthalate with 2-nitrophenyloctyl ether improved the stability of the studied PIMs.
... El estudio reportó el potencial de las cenizas de combustión generadas a partir del carbón, los neumáticos y los RSU tiene el potencial de ser reciclados como catalizadores a través del proceso de reformado de vapor pirolítico-catalítico, mostrando un rendimiento significativamente mayor en el gas total y H2 (Al-Rahbi, 2019). Es bien sabido que los residuos de la industria petroquímica provocan cargas ambientales debido a su contenido peligroso como es el caso de los catalizadores gastados; sin embargo, existe una buena oportunidad en el reciclaje de algunos metales base como V, Ni, Co, Mo, representando una oportunidad económica en el aprovechamiento de estos residuos (Akcil et al, 2015). ...
En los próximos años, el uso de catalizadores sigue aumentando, ya que desempeña un papel importante en la fabricación de productos básicos, petroquímicos, químicos, farmacéuticos y alimenticios, además de servir como una herramienta para la mejora el rendimiento de las nuevas tecnologías energéticas. Por otro lado, los procesos de síntesis de catalizadores generan residuos en los laboratorios y fábricas, convirtiéndose en un desafío ambiental debido a su composición particular. En este contexto, se pueden utilizar herramientas como el análisis de ciclo de vida (ACV) para cuantificar los impactos ambientales e identificar los puntos débiles, que deberán ser mitigados. Por lo tanto, en esta revisión, se evaluaron tres catalizadores: Zn, Pd, Pt, al igual que sus impactos ambientales. Finalmente, se encontraron algunos de los usos potenciales en la reducción de las emisiones de gases de efecto invernadero (GEI) y el aumento en el rendimiento de la producción de energía y urea, así como el aumento del rendimiento en el gas total y de hidrógeno; también se consideró el uso de los residuos de base como catalizadores, por ejemplo, en la industria del petróleo y las cenizas generadas durante los procesos de combustión de residuos sólidos urbanos (RSU), neumáticos y carbón
... In addition, the combination of some main group elements such as N, C, P, and transition metals as active phases can improve the catalytic performance. In general, the most widely used HDS catalysts in industry are Co-Mo/γ-Al 2 O 3 and Ni-Mo/γ-Al 2 O 3 catalysts [4][5][6]. During the high-temperature desulfurization process, sulfur compounds are adsorbed by Mo and removed by H 2 , whereas V as well as Ni presented in heavy oil is deposited on the catalyst surface. ...
Hydrodesulfurization (HDS) catalysts are widely used in petrochemical industries, playing a crucial role in desulfurization process to get high-quality oil. The generation of Al-based spent HDS catalyst is estimated to be 1.2×105 tons per year around the world. The spent HDS catalysts have been regarded as an important secondary resource due to their abundant output, considerable metal value, and regeneration potential; however, if improperly handled, it would severely pollute the environment due to high content of heavy metals. Thus, the recovery of valuable metals from spent HDS catalysts is of great importance from both resource utilization and environmental protection points of view. In this work, recent advances in the spent HDS catalyst treatment technologies have been reviewed, focusing on the recovery of valuable transition metals and environmental impacts. Finally, typical commercial processes have been discussed, providing in-depth information for peer researchers to facilitate their future research work in designing more effective and environmentally friendly recycling processes.
... Eventually, the Ecat becomes an environmental problem since it contains heavy metals, originated from the feedstock, and coke, a byproduct of the cracking reactions. Hence, Ecat is usually disposed in landfills or employed as cement raw material [3,25]. ...
The electrokinetic remediation assistance on the leaching of spent FCC catalysts demonstrated satisfactory performance as an alternative method to the traditional leaching method, aiming to recycle rare earth elements from this solid waste, by former studies. The present work identified the process conditions that improved the mass transfer performance of lanthanum by electrokinetic phenomena, by means of a central composite design and variance analysis. Thereby, the system that operated with the sulfuric acid concentration in the electrolyte of 1 mol/l and the applied electric field of 0.15 V/m, for 8 h of the experiment, was the best in terms of energy and acid consumption per mass of lanthanum recovered, amid the tested conditions.
... It is estimated that vanadium forms 0.019% of the Earth's crust, being its eighteenth most abundant element [4]. Nevertheless, the great number of industrial needs and the increasing consumption of this element, on one hand, and the depletion of the corresponding mineral resources, on the other, require the development of efficient methods for the recovery of vanadium from second-hand sources and industrial waste [5]. Moreover, vanadium is considered as a serious contaminant [6], similarly to mercury, lead, and arsenic [7]. ...
A polymer inclusion membrane (PIM) composed of 50 wt% poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) as its base polymer, 40 wt% Aliquat® 336 as its extractant and 10 wt% dibutyl phthalate (DBP) as plasticizer provided efficient extraction of vanadium(V) from its sulfate solutions adjusted to pH 2.5. It was suggested that V(V) was extracted as VO2SO4− via an anion exchange mechanism. Quantitative back-extraction was achieved in a sulfuric acid solution (6 mol L-1) containing 1 v/v% of hydrogen peroxide. It was assumed that the back-extraction process involved the oxidation of VO2+ to VO(O2)+ by hydrogen peroxide. The newly developed PIM with the optimized composition mentioned above exhibited excellent selectivity for V(V) in the presence of metallic species present in digests of spent alumina hydrodesulfurization catalysts (i.e., Al(III), Co(II), Cu(II), Fe(III), Mn(II), and Ni(II)). The co-extraction of Mo(VI) with V(V) was eliminated by its selective extraction at pH 1.1. The optimized PIM was characterized by contact angle measurements, atomic-force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA)/derivatives thermogravimetric analysis (DTGA), and the stress-strain measurements.
... It is estimated that vanadium forms 0.019% of the Earth's crust, being its eighteenth most abundant element [4]. Nevertheless, the great number of industrial needs and the increasing consumption of this element, on one hand, and the depletion of the corresponding mineral resources, on the other, require the development of efficient methods for the recovery of vanadium from second-hand sources and industrial waste [5]. Moreover, vanadium is considered as a serious contaminant [6], similarly to mercury, lead, and arsenic [7]. ...
A polymer inclusion membrane (PIM) composed of 50 wt% base polymer poly(vinylidenefluoride-co-hexafluoropropylene), 40 wt% extractant Aliquat® 336, and 10 wt% dibutyl phthalate as plasticizer/modifier provided the efficient extraction of vanadium(V) (ini-tial concentration 50 mg L−1) from 0.1 M sulfate solutions (pH 2.5). The average mass and thick-ness of the PIMs (diameter 3.5 cm) were 0.057 g and 46 μm, respectively. It was suggested that V(V) was extracted as VO2SO4− via an anion exchange mechanism. The maximum PIM capacity was estimated to be ~56 mg of V(V)/g for the PIM. Quantitative back-extraction was achieved with a 50 mL solution of 6 M H2SO4/1 v/v% of H2O2. It was assumed that the back-extraction pro-cess involved the oxidation of VO2+ to VO(O2)+ by H2O2. The newly developed PIM, with the op-timized composition mentioned above, exhibited an excellent selectivity for V(V) in the pres-ence of metallic species present in digests of spent alumina hydrodesulfurization catalysts. Co-extraction of Mo(VI) with V(V) was eliminated by its selective extraction at pH 1.1. Charac-terization of the optimized PIM was performed by contact angle measurements, atomic-force microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis/derivatives thermogravimetric analysis and stress–strain measurements. Replacement of dibutyl phthalate with 2-nitrophenyloctyl ether improved the stability of the studied PIMs.
... Nevertheless, some estimations in recent years have estimated production of 840,000 tonnes per year [8] reveals the great extension of the problem. Most of the spent FCC are disposed of in landfills [11], which leads to serious environmental pollution and human health problems so it is must be treated properly. Because of sFCC consists mainly of active silica (SiO2) and alumina (Al2O3), the final spent FCC catalyst can subsequently be employed as cement raw material, or as a partial replacement of cement or sand in cement mortars [12,13]. ...
An laboratory procedure has been developed to obtain lanthanum oxide from spent fluid catalytic cracking catalyst, commonly used in the cracking the heavy crude oil process. Two different spent fluid catalytic cracking catalysts, which are mainly formed by silica and alumina, and a certain amount of rare earths were leached under several conditions to recover the rare earth from the solids waste. Subsequently, liquid phases were subjected to a liquid-liquid extraction process, and lanthanum was quantitatively stripped using oxalic acid to obtain the corresponding lanthanum oxalates. After the corresponding thermal treatment, these solids were transformed into lanthanum oxide. Both, lanthanum oxalates and oxides solids have been characterized by wide techniques in order to investigate the purity of the phases.
... Conventionally, the metal recovery from spent hydroprocessing catalysts is achieved through hydrometallurgical processes, pyrometallurgical processes, or a combination of both. In pyrometallurgical processes, spent hydroprocessing catalyst is subjected to thermal treatment (>1500 °C) that enables recovery of metals (Akcil et al., 2015). In the case of hydrometallurgical processes, different leaching agents (acids, alkali, oxidants, etc.) are used to dissolve and selectively extract the metals from the spent catalyst in an aqueous media (Padh et al., 2019). ...
Bioleaching is considered an eco-friendly technique for leaching metals from spent hydroprocessing catalysts; however, the low bioleaching yield of some valuable metals (Mo and V) is a severe bottleneck to its successful implementation. The present study reported the potential of an integrated bioleaching-chemical oxidation process in improved leaching of valuable metals (Mo and V) from refinery spent hydroprocessing catalysts. The first stage bioleaching of a spent catalyst (coked/decoked) was conducted using sulfur-oxidizing microbes. The results suggested that after 72 h of bioleaching, 85.7% Ni, 86.9% V, and 72.1% Mo were leached out from the coked spent catalyst. Bioleaching yield in decoked spent catalyst was relatively lower (86.8% Ni, 79.8% V, and 59.8% Mo). The low bioleaching yield in the decoked spent catalyst was attributed to metals’ presence in stable fractions (residual + oxidizable). After first stage bioleaching, the integration of a second stage chemical oxidation process (1 M H2O2) drastically improved the leaching of Ni, Mo, and V (94.2–100%) from the coked spent catalyst. The improvement was attributed to the high redox potential (1.77 V) of the H2O2, which led to the transformation of low-valence metal sulfides into high-valence metallic ions more conducive to acidic bioleaching. In the decoked spent catalyst, the increment in the leaching yield after second stage chemical oxidation was marginal (<5%). The results suggested that the integrated bioleaching-chemical oxidation process is an effective method for the complete leaching of valuable metals from the coked spent catalyst.
... Road runoff has been identified as an REE source in the urban environment, accumulating in soils near high traffic roads (Mleczek et al., 2018). A possible REE source in road built-environments is spent fluid catalytic crackinga catalyst used in the conversion of crude oil into lighter gasoline (Akcil et al., 2015) and reutilized in asphalt mortar as a mineral filler (Xue et al., 2020) and catalysts used in automobiles and petroleum refinery operations (Kulkarni et al., 2006). ...
Metals, including rare earth elements (REE), are the cornerstone of our current and future low-carbon urban infrastructure. This study looks at different waste resources and contaminated materials present in the urban setting as REE sources. Wastes and other dilute sources such as incineration ashes, sediments, and mine tailings are not only essential sources of REE in achieving a circular, carbon-neutral economy but may be the most realistic one. E-waste, being the most REE concentrated waste, faces serious reservations regarding handling in large-scale facilities, and this waste is generally landfilled. In this study, we analyzed REE total concentrations and pH desorption curves in ten dilute sources of REE: Ferrochrome slag from a mine in South Africa, sediments retrieved form stormwater ponds in Denmark, coal fly ashes, municipal solid waste (MSW) fly ashes, wood fly and bottom ashes and sewage sludge fly ashes (ashes from different sources). After analyzing different residues, we found that coal fly ashes and stormwater retention pond sediments present the most promising ones. While coal fly ashes have the highest critical REE contents from the studied wastes, the sediments collected from a stormwater retention pond showed the highest REE leachability. We can find Nd, Dy, and Er – all critical REE – in sediments/soils near highways, coal ashes, and bauxite residue. Overall, coal fly ashes contain the highest critical REE contents found in the studied wastes but sediments collected from stormwater water ponds present the highest leachable REE. In fact, up to 100% of total REE found in these sediments are leachable at room temperature and low pH. Future REE resource extraction efforts should account for REE speciation in wastes and not only total contents.
... Further study on the recovery and reuse of the spent catalyst is necessary. The recovery of the spent hydroprocessing catalyst has attracted considerable attention due to environmental regulations which register the spent catalyst as a hazardous waste material [64,65] Although their disposal could cause environmental issues, spent catalysts containing high metal concentrations can serve as secondary raw materials. Several approaches have been proposed for the recovery of metals from spent hydroprocessing catalysts [66], which include direct melting, calcination, and melting, chlorination, and salt roasting [67,68]. ...
This study reports the hydrothermal liquefaction (HTL) of microalgae Spirulina platenesis in the presence of alcohol or formic acid co-solvents. HTL runs are performed in a 1.8-L batch reactor at 300 °C using an alcohol (methanol and ethanol) or formic acid co-solvent. Consequently, hydrodeoxygenation (HDO) of resultant algal biocrude is performed at 350 °C for 2 h under high hydrogen pressure (~725 psi) using the Ru/C catalyst. The HTL results are compared with the control HTL run performed in water only. The results of the study show that the addition of co-solvents leads to a 30–63% increased biocrude yield over the control HTL run. Formic acid results in a 59.0% yield of biocrude, the highest amongst all co-solvents tested. Resultant biocrudes from formic acid-assisted and ethanol-assisted HTL runs have 21.6% and 3.8–11.0% higher energy content, respectively, than that of the control run. However, that of the methanol-assisted HTL results in biocrude with 4.2–9.0% lower energy density. Viscosity of biocrude from methanol- or ethanol-assisted HTL is higher than the control HTL but formic acid-assisted HTL results in a less viscous biocrude product. In addition, the HDO study leads to a 40.6% yield of upgraded oil, which is characterized by a higher net energy content and lower O/C and N/C ratios when compared to the initial HTL biocrude.
... Further study on the recovery and reuse of the spent catalyst is necessary. The recovery of the spent hydroprocessing catalyst has attracted considerable attention due to environmental regulations which register the spent catalyst as a hazardous waste material [64,65] Although their disposal could cause environmental issues, spent catalysts containing high metal concentrations can serve as secondary raw materials. Several approaches have been proposed for the recovery of metals from spent hydroprocessing catalysts [66], which include direct melting, calcination, and melting, chlorination, and salt roasting [67,68]. ...
This study reports the hydrothermal liquefaction (HTL) of microalgae Spirulina platenesis in the presence of alcohol or formic acid co-solvents. HTL runs are performed in a 1.8-L batch reactor at 300 °C using an alcohol (methanol and ethanol) or formic acid co-solvent. Consequently, hydrodeoxygenation (HDO) of resultant algal biocrude is performed at 350 °C for 2 h under high hydrogen pressure (~725 psi) using the Ru/C catalyst. The HTL results are compared with the control HTL run performed in water only. The results of the study show that the addition of co-solvents leads to a 30–63% increased biocrude yield over the control HTL run. Formic acid results in a 59.0% yield of biocrude, the highest amongst all co-solvents tested. Resultant biocrudes from formic acid-assisted and ethanol-assisted HTL runs have 21.6% and 3.8–11.0% higher energy content, respectively, than that of the control run. However, that of the methanol-assisted HTL results in biocrude with 4.2–9.0% lower energy density. Viscosity of biocrude from methanol- or ethanol-assisted HTL is higher than the control HTL but formic acid-assisted HTL results in a less viscous biocrude product. In addition, the HDO study leads to a 40.6% yield of upgraded oil, which is characterized by a higher net energy content and lower O/C and N/C ratios when compared to the initial HTL biocrude.
... In the manganese dissolution by sulfur-oxidizing bacteria, oxidation of sulfur to sulfuric acid involves enzymatic steps taking place in cells periplasmic space (Reaction (1)) (Cerruti et al. 1998). The biogenic sulfuric acid dissolves the manganese according to Reactions (2)-(4) (Akcil et al. 2015;Biswal et al. 2018). Throughout the process, the protons generated via bio-oxidation of S 0 were balanced by the protons consumption via the oxidation of the metals (Marra et al. 2018). ...
Manganese is extensively used in various advanced technologies. Due to high manganese demand and scarcity of primary manganese resources, extracting the metal from spent batteries is gaining increasing interest. The recycling of spent batteries for their critical metal content, is therefore environmentally and economically feasible. The conventional pyro- and hydrometallurgical extraction methods are energy-intensive or use hazardous chemicals. Bioleaching of manganese from spent batteries as secondary resource has been suggested to meet two objectives: reduce environmental footprint and turn waste into wealth. A bioleaching process can operate with less operating costs and consumption of energy and water, along with a simple process, which produces a reduced amount of hazardous by-products. Hence, this review discusses various approaches for bioleaching manganese from secondary resources using redoxolysis, acidolysis, and complexolysis. Candidate microbes for producing inorganic and organic biolixiviants are reviewed, along with the role of siderophores and extracellular polymeric substances as other effective agents in manganese extraction. The three main types of bioleaching are discussed, incorporating effective parameters with regard to temperature, pH, and pulp density, and future perspectives for manganese bioleaching and provided.
Graphical abstract
... A typical fluid catalytic cracking (FCC) catalyst consists of a mixture of an inert matrix (kaolin), an active matrix (alumina), a binder (silica or silica-alumina), and a rare earth-exchanged Y-zeolite. The FCC catalysts that are generally used are highsilica faujasites with X-type, Y-type, and ZSM-5 zeolites [4]. In the FCC process, a large part of the feedstock is converted into coke, and a small amount of alumina (Al), iron (Fe), vanadium (V), nickel (Ni), etc., impurities in crude oil will gradually deposit on the catalysts [1]. ...
The problem of spent fluid catalytic cracking (SFCC) catalyst resource utilization, draws more and more attention to system analysis. SFCC was leached in an oxalic solution for comprehensive utilization. The results showed that for a D50 ≤ 17.34 μm, the catalyst leached for 240 min at 95 °C in the presence of a 2 mol/L oxalic acid solution, and the extent of leaching of V, Ni, Fe, and Al was 73.4%, 32.4%, 48.2%, and 36.8%, respectively. Studies on the occurrence state of the main ions (V, Ni, Fe, and Al) in the leaching solution were presented. Additionally, the separation of the main ions from such a solution by the “solvent extraction-stripping-hydrothermal precipitation-comprehensive recovery of valuable metal” process was studied. The immobilization rates of vanadium and nickel in geopolymers can be obtained using the toxicity characteristic leaching procedure (TCLP) test, and the geopolymers prepared by SFCC leaching residues can be considered a non-hazardous material. A process diagram of the comprehensive utilization of SFCC catalysts is presented.
... This was because the catalysts commonly used in industry were generally composed of three parts: catalyst active components, auxiliary agents and carriers. Al 2 O 3 , SiO 2 , and amorphous silicon-alumina are commonly used catalysts (Akcil et al. 2015;Delia Rojas-Rodríguez et al. 2012). ...
With the extensive use of nonferrous metals and metal catalysts, solid wastes containing heavy metals release metal ions into soil and surface water through erosion and leaching. This is one of the major threats to the global environment and human health. Studying the characteristics and impact factors of heavy metal leaching from solid waste is a critical part of managing spent catalysts and environmental risk. In this work, the characteristics of and factors that influence leaching and seepage release from typical spent catalysts and lead–zinc smelting slag were studied. The results indicated that metal ions leached more easily in an acidic environment (pH 4.5) and an environment with DOM than in a neutral environment (pH 7.0). Metal ion leaching was favored by a liquid-to-solid ratio of 20:1. The concentrations of metal ions released from the spent catalysts in sequential leaching experiments were higher than those in column leaching experiments. Leaching of metal ions in the presence of different leaching agents and from different spent catalysts can be described by different controlling models of the shrinking core model, but changes in the liquid-to-solid ratio showed no obvious correlation with changes in the metal release mechanism. These results provide important information for spent catalyst management and risk prevention and control.
Cobalt demand has witnessed tremendous growth in recent years due to its wide utilization in many critical industries. However, more than half the world’s demand for cobalt is supplied only by one country, raising concerns about the potential future supply. Considering the status of cobalt as a critical raw material, recycling is viewed as an option to provide an alternative stream of supply by recovering cobalt from secondary resources. In this paper the importance of cobalt recovery from secondary resources is highlighted. The current state of research on Co recovery from secondary resources such as catalysts, magnets, superalloys, cemented carbides, rechargeable batteries, and metallurgical wastes are discussed. The industrial-scale cobalt recycling has also been reviewed to give a better overview of the overall progress. This review provides insights into the future outlook and challenges associated with cobalt recovery from secondary resources. Despite the challenges, cobalt recovery technologies from secondary resources should be further developed.
In this study, the reactivation and modification of the spent Residue Fluid Catalytic Cracking (RFCC) catalyst using sulfuric acid and citric acid as acids treatment was evaluated by varying the acid solution concentrations. The effect of acid types and acid-solution concentrations on structural, textural, and acidic properties of spent RFCC catalyst was observed using X-ray diffraction, X-ray fluorescence, N2-sorption and pyridine-probed Fourier transform infrared measurements. Catalytic cracking of palm oil was used to evaluate the catalytic activity of the acid-treated catalysts. All the results showed the different beneficial effects of the sulfuric acid- and citric acid- treatments on the physicochemical properties of the modified catalyst with an improvement of surface area and pore volume of catalysts as well as the crystallinity due to the metal and matrix material removal. The sulfuric acid-treated catalysts have higher Brønsted/Lewis (B/L) ratio than the citric acid treatment, while the citric acid-treated catalysts have lower B/L ratio due to the enhancement of Lewis acid site. The acid-treated catalysts showed better performance than the non-treated catalyst. The selectivity of the kerosene-diesel range product fraction increased with the acid concentrations treatment.
A comprehensive data inventory of the current materials cycle in industry and society is crucial for an informed discussion and for decision‐making on the supply of raw materials. Particularly, it is key to understand how these materials are functionally and nonfunctionally recycled, and enable the assessment of recycling indicators needed for the monitoring of circular economy. In this context, a material system analysis (MSA) of cobalt for the European Union (EU) from 2012 to 2016 is presented and discussed. Detailed results are provided for the year 2016, and the evolution of the flows over time is presented from 2012 to 2016. In addition, six indicators are calculated to characterize the cobalt cycle. In 2016, the EU28 embedded around 24,000 metric tons (t) of cobalt in manufactured products, and 33,700 t were put into use. The main losses of the system are due to nonselective collection of postconsumer waste (disposed), and nonfunctional recycling of old scrap. From the years analyzed, it was possible to detect a shift in the imports; the import of primary material decreased more than 99% between 2012 and 2016, and the import of semiprocessed and processed materials increased around 31% in the same period. This indicates that after 2012, the EU became more dependent on imports in downstream stages of the supply chain. One way to decrease this dependency is to establish higher collection targets, and to establish recycling targets based on the recovery of single materials, in order to decrease the amount dissipated through nonfunctional recycling.
Recycling of valuable metals from spent catalysts in a green way is gaining extensive interest for economic and environment reasons. In this study, we developed novel hydrophobic deep eutectic solvents to extract Mo from spent catalysts. The hydrophobic DESs have been designed and synthesized by mixing one molar of the quaternary ammonium salt and two molars of various saturated fatty acids with different carbon chain lengths. The extraction ability and extraction mechanism of these DESs were studied, some factors influencing the extraction efficiency, including the structure of hydrogen bond acceptors and hydrogen bond donors, initial aqueous pH, reaction time and temperature, phase ratios were investigated. It is found that the synthesized hydrophobic DESs exhibit excellent extraction performance towards Mo, where the Mo distribution ratio is more than 2200 in the presence of other metals, corresponding to extraction efficiency of 99% at optimal reaction conditions. This work reveals a distinct class of materials, guiding an effective and green way for spent catalyst treatment.
Implications
Novel hydrophobic deep eutectic solvents have been developed to extract Mo from spent catalysts, the synthesized hydrophobic DESs possess several advantages such as green, low price, low toxicity, biodegradable. It exhibits excellent extraction performance under an optimized extraction condition. This work reveals a distinct class of materials, guiding a promising way for green and economical utilization of spent catalysts.
The purpose of this work is to investigate desorption efficiency for regenerating a crude oil-contaminated catalyst by using an ex-situ surfactant/solvent washing technique. We employed six types of surfactants and solvents for optimization, and established an optimal mixture of surfactant and solvent for the removal of crude oil from the contaminated catalyst. The efficiency of the surfactant/solvent mixture for the removal of crude oil from the contaminated catalyst was determined based on the mass ratio of surfactant to solvent, contact time, pH, and temperature. The raw catalyst, crude oil-contaminated catalyst, and after washing catalyst were characterized by interracial rheometer, zeta-potential analyzer, and scanning electron microscope. We found that the Brij-58/1,2-dimethylbenzene mixture could provide superior crude oil removal efficiency. At a higher mass ratio of 1,2-dimethylbenzene, the crude oil removal rate of the contaminated catalyst exceeds 95%. This result is attributed to the addition of the solvent to the surfactant solution. The solvent can significantly decrease the surfactant’s CMC and increase the micelle’s number, thereby enhancing the mixture’s washing efficiency. Since aromatic solvents and crude oil components have similar structures in terms of polarity and aromaticity, the Brij-58/1,2-dimethylbenzene mixed system has a strong affinity for crude oil components.
The biomaterials have gained the attention for utilization as sustainable alternatives for petroleum-derived products due to the rapid depletion of petroleum resources and environmental issues. Chitosan is an economical, renewable and abundant polysaccharide having unique molecular characteristics. Chitosan is derived by deacetylation of chitin, a natural polysaccharide existing in insects' exoskeleton, outer shells of crustaceans, and some fungi cell walls. Chitosan is widely used in numerous domains like agriculture, food, water treatment, medicine, cosmetics, fisheries, packaging, and chemical industry. This review aims to account for all the efforts made towards chitosan and its derivatives for utilization in the petroleum industry and related processes including exploration, extraction, refining, transporting oil spillages, and wastewater treatment. This review includes a compilation of various chemical modifications of chitosan to enhance the petroleum field's performance and applicability.
Bioleaching is an eco-friendly alternative for the extraction of metals from the spent fluid catalytic cracking catalyst (SFCCC). Acidothiobacillus ferrooxidans (A. ferrooxidans) are the most widely reported bacteria in leaching but remained unexplored for SFCCC till date. The present study proposes a cleaner, environmentally friendly process to leach metals from SFCCC by A. ferrooxidans. Batch bioleaching of metals was carried out with unadapted and adapted A. ferrooxidans. Experiments were performed by varying the pulp density (PD) (1 to 20%) at two different initial Fe(II) concentrations i.e. 2 g/L [M2Fe(II)] and 8.84 g/L [M8.84Fe(II)]. The results showed that adapted A. ferrooxidans leached out metals better than unadapted ones. Even though the loss of Iron to Jarosite formation was higher in M8.84Fe(II) than in M2Fe(II), leaching remained higher in M8.84Fe(II). Jarosite formation was minimized by maintaining the pH of the medium to 2±0.1. Maximum leaching efficiency was observed at 1% PD. At this concentration. A. ferrooxidans growth was triggered which increased the production of Fe(III), thereby increasing leaching efficiency. Increase in PD led to a decrease in metal leaching efficiency. The maximum leaching observed by A. ferrooxidans is Al (35%), Ti (14%), Ni (27%) and V (56.5%). The amount of Al leached (70 mg/gm of SFCCC) suggests SFCCC be the potential secondary source of Al compared to popular secondary sources such as red mud and other spent catalysts. Al and V were better leached by A. ferrooxidans while organic acids were more suitable to extract Ti and Ni from SFCCC.
This paper introduces the composition and hazard characteristics of oily sludge. Combining energy recovery and environmental protection, pyrolysis has been proven to be a potential technology. To further recover resources and reduce environmental risks, catalytic pyrolysis of oily sludge has attracted extensive attention. This work first discusses the advantages and disadvantages of the two chief types of catalytic pyrolysis reactors. Next, the effects of four major categories of catalysts employed in oily sludge pyrolysis on the quality of products are summarized and discussed. In addition, the disposal methods of spent catalysts are also introduced. Finally, the challenges and future research trends of catalysts are expected. Besides, the disposal methods of spent catalysts have also been outspread to avoid the waste of resources and secondary pollution caused by spent catalysts.
The catalyst Mo–Ni/Al2O3 is commonly used in the hydrodesulphurization of petroleum fractions. The catalyst is discarded when its catalytic activity does not meet the requirement of the process, and the spent catalyst is usually classified as hazardous waste due to its significant heavy-metal content. The spent catalyst usually has a high commercial recovery value as a secondary resource for high-value metals, but the simple and high efficiency recovery method is still lacking. A high-efficiency recovery method for Mo and Ni from spent Mo–Ni/Al2O3 catalyst via soda roasting and solvent extraction was developed in this study. MoO3 interacts with Al2O3 and forms a new phase, Al2(MoO4)3, during blank roasting at 600–700 °C. Al2(MoO4)3 further transforms into NaMoO4 during soda roasting at 950 °C, and over 99.1% of Mo can be leached using hot water (60 °C). Solvent extraction with the trioctyl tertiary amine (N235) is employed to separate Mo from the leaching solution, and approximately 99.45% of Mo can be enriched through single-stage extraction. Around 99.2% of Mo can be stripped from loaded N235 using 8 M NH3•H2O. Further, PO4³⁻ and SiO3²⁻ can be removed from the stripping solution using Mg(NO3)2, and Mo is recycled in the form of MoO3, i.e., a product of the ammonium precipitation and calcining process. Over 99.3% of Ni can be leached from the solid residue using 30% volume fraction of H2SO4 and the solvent extraction can be enriched using diiso-octylphosphate (DP). Ni is finally recycled from the stripping solution as NiSO4•2H2O via evaporative crystallization. The total Mo and Ni recovery efficiencies of the newly developed integrated approach are 97.8% and 98.1%, respectively. Al is also recycled in the form of α-Al2O3 via chemical precipitation and calcination. The proposed approach is simple, with a high recovery rate and high selectivity, and can be applied to the recycling and disposal of spent Mo–Ni/Al2O3 catalyst.
Electronic waste (e-waste), as hazardous waste, is a promising secondary resource of precious metals. The extraction of precious metals from e-waste has great environmental and economic benefits. Most of the existing methods have high energy consumption, environmental pollution or low recovery efficiencies. This study proposed the application of green electrodeposition technology to realize targeted recovery of Ag-Pd alloy from Ni, Cu, Ag, Pd, Bi polymetallic e-waste leaching solution. Linear sweep voltammetry was conducted to determine the feasibility of targeted extraction. The high purity of Ag-Pd alloy was realized by controlling the potential. The recovery efficiencies of Ag and Pd were 97.72% and 98.05% after 5 hours in 0.5 mol/L HNO3 with applied potential of 0.35 V. The results indicated the formation of monophase Ag-Pd alloy. Besides, the effect of acidity and potential on the particle size of alloy was analyzed. Chronoamperometric method was applied to study the electrodeposition mechanism. The Ag-Pd electrodeposition followed three-dimensional instantaneous nucleation and growth mechanism analyzed with Scharifker-Hills model, thus producing a solid solution. The nucleation site increased with the overpotential. This study provides a novel, efficient and green approach for the targeted recovery of Ag and Pd from the complex multi-metal system of e-waste.
Zinc oxide (ZnO) and titanium dioxide (TiO2) are loaded on the spent fluid catalytic cracking catalyst (FCC) via an impregnation method to form the composite material, which is named as Zn–Ti/FCC in this article. The photocatalytic performance of the Zn–Ti/FCC composite is evaluated by degradation efficiency of methylene blue (MB). After the photocatalytic degradation, the MB was almost completely degraded with the Zn–Ti/FCC composite. The lattice mismatch of the ZnO and TiO2 lead to an electric field at the interface between the ZnO and TiO2. The Fermi levels of ZnO and TiO2 reach a new equalization state, the separates the charges leading to higher photocatalytic activity. Because of the formation of a heterojunction between ZnO and TiO2, the conduction band (CB) of ZnO is more active than TiO2, the electrons in the CB of ZnO would transfer to the CB of TiO2. The heterojunction between ZnO and TiO2 promote the separation of the electron hole pairs, which can improve the photocatalytic degradation of MB. The degradation rate of methylene blue with the Zn–Ti/FCC, Zn/FCC and Ti/FCC have reached to nearly ~ 98%, ~ 52% and ~ 59%, respectively. The excellent photocatalytic degradation performance of the Zn–Ti/FCC towards MB is expected to further develop the dye processing industry. Moreover, these composites fabricated process can also provide an effective method to dispose the spent FCC catalyst in industry.
Industrial applications and environmental awareness recently prompted vanadium recovery spell from secondary resources. In this work, a polymer inclusion membrane containing trioctylmethylammonium chloride as carrier was successfully employed in electrodialysis for vanadium recovery from acidic sulfate solutions. The permeability coefficient of V(V) increased from 0.29 μm·s⁻¹ (without electric field) to 4.10 μm·s⁻¹ (with the 20 mA·cm⁻² current density). The transport performance of VO2SO4⁻, which was the predominant species containing V(V) in the acidic region (pH <3), was influenced by the aqueous pH value and sulfate concentration. Under an electric field, a low concentrated H2SO4 solution (0.2 M) effectively stripped V(V) from the membranes, avoiding the requirement of a highly concentrated H2SO4 without electric field. Under the optimum conditions, the permeability coefficient and flux reached 6.80 μm·s⁻¹ and 13.34 µmol·m⁻²·s⁻¹, respectively. High selectivity was observed for the separation of V(V) and Mo(VI) from mixed solutions of Co (II), Ni (II), Mn (II), and Al (III). Additionally, the separation between Mo(VI) and V(V) was further improved by adjusting the acidity of the stripping solution. The V(V) selectivity for the resulting membrane was higher than that of commercial anion exchange membranes.
Recovering metal values in hazardous spent hydrogenation catalysts is of vital economic and environmental importance. Herein, the selective recovery of valuable molybdenum (Mo), vanadium (V), and nickel (Ni) from spent hydroprocessing catalysts are achieved by using a sulfuric acid leaching-stepwise extraction process. After roasting in the air at 400 °C, the valuable metals are effectively leached within 20 min by 1 mol/L sulfuric acid at 75 °C. The leaching efficiency of Al, Ni, Mo, and V is 22.16%, 99.44%, 98.59%, and 100%, respectively. Based on the species analysis of the leachate, a stepwise extraction separation route was established for selective recovery of Mo, Ni, and V from the acidic leachate. Mo and V are preferentially co-extracted by the mixed TOA/Cyanex272 with a molar ratio of 7:3, which exhibits an excellent extraction selectivity over Ni and Al. Increasing the concentration of Cyanex272 in the mixed system can effectively improve the selective stripping of vanadium but slightly inhibit its extraction. Residual Ni in the raffinate can be selectively separated by 50%(V/V) commercial HBL110 with an extraction efficiency of 98.5%. Especially, the reductive sodium sulfite can greatly enhance the selective stripping of vanadium from the loaded organic phase. Residual Mo in the organic phase can be well stripped with an alkaline solution. The selective stripping mechanism of vanadium is revealed by the FT-IR and Raman spectra. This work proposes a sustainable stepwise separation route for recovering valuable metals in the spent hydroprocessing catalyst.
The spent hydroprocessing (HDP) catalysts containing a considerable quantity of oily pollutants and valuable metals including nickel (Ni), molybdenum (Mo), and vanadium (V) are hazardous wastes to be treated urgently. Herein, a sustainable process featuring vacuum pyrolysis and fast acidic elution was proposed to recycling the residual oils and metal values from the uncrushed spent HDP catalysts. The removal efficiency of oils by vacuum pyrolysis reached more than 85% at 400 °C in 60 min. The Ni, Mo, and V deposited on the uncrushed catalysts were fast eluted and recovered by 1 mol/L sulfuric acid solution within 15 min. The ultrasound-assisted leaching could promote metal recovery within 10 min but then has no difference with stirring leaching. The leaching efficiencies of Ni, Mo, and V reached over 95% with few Al being dissolved (7.63%). The obtained uncrushed Al2O3 residue could be potentially recycled as the support for a fresh catalyst. The liquid film diffusion control mechanism was disclosed to represent the fast leaching process of metal values. These results provided a promising and green approach for the sustainable recovery of both residual oils and valuable metals from spent hydroprocessing catalysts.
The potential of Acidithiobacillus (Thiobacillus) genus members, namely Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, for bioleaching purposes is known. Specifically, previous studies have shown the potential of A. thiooxidans strain DSM 26636 used in bioleaching processes to remove metals in high-metal-content matrices. All Acidithiobacillus growth-monitoring techniques available to date, including sulfate production, commonly used, present disadvantages. Thus, the current work shows a technique based on DNA quantification to evaluate the growth of A. thiooxidans DSM 26636, which is useful even in the presence of a high-metal-content residue. This proposed methodology may represent a functional complementary tool to evaluate Acidithiobacillus growth to develop biometallurgical applications.
Developed economies such as the USA and European Union (EU) have classified antimony as a critical raw material. China leads the global antimony production (67% on an average from 2015 to 2019) followed by Russia and Tajikistan. Antimony has been applied in the industry (plastics, etc.) and new/emerging technologies (cell panels, infrared, etc.) where antimony trioxide (Sb2O3) is its most produced and used compound. With technological advances, recent trends indicate a growing demand for this metal; however, with the on-going production rate, antimony is anticipated to become one of the scarcest metals by 2050. Several minerals of antimony exist; nevertheless, stibnite (Sb2S3) is the primary mineral. Extractive metallurgical routes such as pyro and hydro-metallurgy have found industrial applications for stibnite processing; however, bio-hydrometallurgy is slowly gaining momentum. In this piece of review, the world-wide scenario of antimony production, recent market trends along with the common and current research advances related to applications of antimony in emerging technologies is presented. Comprehensive details along with the recent advances related to stibnite processing through the aforementioned extractive metallurgy routes, their technological improvements and antimony purification/recovery methods from leach solutions are also discussed. Furthermore, the future perspectives in terms of research and industrial needs are discussed and summarized.
An effective method comprising the immersion in dilute sulfuric acid and the leaching in a mixture of sulfuric acid and oxalic acid under ultrasonic irradiation is provided to improve the removal effect of harmful metals in spent FCC catalyst without destroying the zeolite Y framework and the microstructure of spent catalyst particle. The influence of different experimental conditions on the regeneration effect of spent catalyst is studied by using SEM, EPMA-EDX, XRD, ICP, N2 adsorption, and particle size analysis techniques. The experimental results show that immersion in sulfuric acid can effectively restore blocked pores and increase the specific surface area of spent catalyst by 51.7% compared with the untreated spent catalyst, which is beneficial to the subsequent acid leaching. After leaching in a mixture of 0.5 mol/L oxalic acid and 2 wt.% sulfuric acid for 30 min at 70 °C with an ultrasonic power of 250 W, the regenerated catalyst with complete particle structure and zeolite Y framework is obtained with the removing rates of Fe, V, and Ni being 36.2, 43.8 and 30.1 %, respectively, whereas Al loss is only 7.9 %. Compared with conventional leaching, ultrasonic assisted leaching only needs 1/4 of the time to achieve much the same harmful metal removal effect and has superior advantages in retaining the integrity of particles.
This study proposes a technical route toward the comprehensive recovery of valuable metals from spent Ni–Mo/γ–Al2O3 hydrofining catalysts, which were employed to remove S, N, and O elements and metal–organic compounds from crude oil and petroleum products. Additionally, the process conditions are optimized, thereby providing good economic and environmental benefits. Sodium carbonate-assisted roasting of the spent catalyst effectively improves the secondary pollution and leaching effect. After Al, Mo, and Ni elements in the spent catalyst were converted into NaAlO2, Na2MoO4, and NiO, more than 99.8% of the metal ions entered the leaching solution, minimizing the loss. A synergistic extraction system using the di-(2-ethylhexyl)phosphoric acid (P204) and tri-n-octylamine (TOA) extractants were employed to extract molybdenum from the clarified acid leaching solution, and more than 97.5% of Mo was separated from Al and Ni. The MoO3 product was obtained by stripping with ammonia, followed by evaporating, and roasting. Furthermore, by adding ammonia to adjust the pH value of the molybdenum extraction solution to 4, 98.0% of the Al was extracted by P204. Subsequently, a Na2S precipitation agent was employed to convert Ni²⁺ into Ni(OH)S with a precipitation efficiency of 97.9%. Ultimately, the comprehensive recovery efficiencies of Al, Mo and Ni were 97.5%, 95.5%, and 90.9%, respectively, thereby realizing the comprehensive recovery of metals in the spent catalyst.
Praworządność, poprzez niezależne sądownictwo, poszanowanie praw człowieka, równość wobec prawa oraz przywiązanie do zasad, które stanowią podstawę prawdziwych demokracji, dotyczy wszystkich trzech wymiarów zrównoważonego rozwoju: gospodarczego, społecznego i środowiskowego. W artykule przedstawiono ramy dyskusji na temat roli praworządności na podstawie analizy procesu włączania pojęcia praworządności do Celów Zrównoważonego Rozwoju, przyjętych we wrześniu 2015 roku w dokumencie Transforming our world: the 2030 Agenda for Sustainable Development (dalej jako „Agenda 2030”). Zaakcentowano tło debaty na temat praworządności w ONZ, a także opisano, w jaki sposób cele zrównoważonego rozwoju określają praworządność, w szczególności Cel 16, zatytułowany: „Promowanie pokojowych i integracyjnych społeczeństw na rzecz zrównoważonego rozwoju,
zapewnienie wszystkim dostępu do wymiaru sprawiedliwości oraz tworzenie skutecznych, odpowiedzialnych i integracyjnych instytucji na wszystkich poziomach”, mający wpływ na ocenę praworządności Agendy 2030. Wskazano na aktualność prowadzonych rozważań w kontekście krytycznej dyskusji nt. standardów praworządności, jaka toczy się obecnie na forum Unii Europejskiej. W końcowych
rozważaniach podkreślono, że chociaż wyniki monitorowania postępów w realizacji celów zrównoważonego rozwoju wskazują na negatywny spadek w kierunku osłabienia i stagnacji praworządności na świecie, to nowa agenda rozwoju może wzmocnić międzynarodową praworządność.
Europejski Zielony Ład jest najbardziej ambitną strategią społeczno-gospodarczej transformacji nie tylko w historii integracji europejskiej, ale szerzej we współczesnej historii Zachodu, a poprzez swoje globalne oddziaływanie zapewne i świata. 30 lat po tym jak narody Europy Środkowo-Wschodniej weszły na ścieżkę transformacji od komunizmu do wolnorynkowej demokracji, dziś, jako część wspólnoty jaką jest Unia Europejska, wchodzimy na ścieżkę ku neutralności klimatycznej i w pełni zrównoważonego rozwoju. Ta strategia jest nie tylko naszym wkładem w powstrzymanie katastrofy klimatycznej, ale też sposobem na zapewnienie Europie trwałego wzrostu, a Europejczykom dobrobytu w najbliższych dziesięcioleciach – bez obciążania innych skutkami degradacji środowiska, nieodwracalnych zmian klimatycznych, czy społecznymi skutkami rozwoju gospodarczego.
W tym kontekście niniejsza monografia, nie tylko podejmuje refleksję nad całym spektrum, często nieoczywistych skutków jakie niesie systemowa transformacja ku neutralności klimatycznej i zrównoważonemu rozwojowi, nie tylko przywraca dyskusji o Europejskim Zielonym Ładzie ramy rygoru naukowego, ale stawia ją w perspektywie procesu jakim jest doskonalenie warsztatu naukowca.
The deoiling process is a critical issue in catalyst regeneration and recovery of precious metals from spent catalysts. This study developed a fast and efficient method to recover crude oil from spent hydrodesulphurization (HDS) catalysts. We employed four solvents (p-xylene, acetone, dichloromethane, and n-hexane) with different polar and aromatic properties to remove crude oil from the spent catalyst. The effects of environmental factors, such as contact time, ratio of catalyst to solvent, temperature, stirring rate, and particle size on washing efficiency were investigated. The crude oil and solvent in the oil-containing washing solution were then effectively separated and recovered. The recovered solvent was used to evaluate solvent cycle washing performance, and the recovered oil was analyzed by gas chromatography-mass spectrometry. The spent and deoiled catalysts were characterized by scanning electron microscope, interracial rheometer, and contact angle. The results showed that p-xylene, which has similar polarity and aromaticity to the molecular structure of crude oil, achieved an excellent crude oil washing effect. The crude oil washing efficiency of the spent catalyst can exceed 94% in 2 minutes. Furthermore, the solvent was recycled 10 times, and still maintained a removal efficiency of over 93% for crude oil in the spent catalyst. Compared to crude oil, recovered oil has less viscosity, ash, residual carbon, and a higher heat of combustion, allowing it to be more easily refined and recovered, and to gain more energy as an energy source.
Solvent extraction separation of molybdenum (Mo) from the sulphate mediated leach solution bearing Aluminium (Al) and Nickel (Ni) was carried out using N-Methyl-N, N, N-tri-octyl-ammonium chloride. Extensive investigation for extraction study molybdenum in the function of time, Eq.pH, extractant concentration, diluents, temperature, strip solution concentration and phase ratio(A:O) for both extraction and stripping was examined to attain a suitable condition on its selective and enriched extraction. As per the equilibrium study and increasing trend of Eq. pH (pHe) at the correspondence initial pH, it was apparent about association of 1 mol of H⁺ ion during extraction which with was further supported on extraction of Mo as HMO4⁻ at the pHe of 3.48. The association of 1 mol of exrractant during the extraction of Mo was also well evident from the slope analysis study. This indicates about anion exchange phenomenon due to Cl⁻ ion of the N-Methyl-N, N, N-tri-octyl-ammonium chloride (extractant) with HMo4⁻ from aqueous phase during complex formation reaction. The FTIR of the organic sample before and after extraction further confirms in support of the complex formation of the molybdenum with the extractant during extraction. The extraction isotherm was constructed at optmum extraction condition: pHe of 3.48 with 0.08M N-Methyl-N, N, N-tri-octyl-ammonium chloride predicts on need of 2-counter current stages for quantitative extraction of Mo at A:O = 3:1. To investigate the regeneration behaviour of adopted extractant along with enriched stripping of molybdenum, ammoniacal reagents were used in stripping study. The stripping of Mo showed promising and efficient using the mixture of the ammoniacal reagents (NH4OH + NH4Cl) over the either of the solo reagents. The stripping Mc-Cabe Thiele diagram was plotted using 2M NH4OH + NH4Cl ensures on quantitative stripping of Mo at SO: SS = 2:1 at 2 no. of stages. Both extraction and stripping isotherm results are validated at predicted isotherm conditions by 6-cycles counter current simulation (CCS) study leading to obtain 6-fold enrichment of Mo in stripped solution phase. The subsequent enriched content of Mo (∼60 g/L) in stripped solution phase was precipitated out followed by calcinations 400 °C to obtain a high pure MoO3. The recovered calcined product as MoO3 resulted through the proposed processing approach was as ascertained from XRD analysis.
Spent hydrodesulfurization (HDS) catalysts, containing considerable amount of pollutants and metals including vanadium (V), molybdenum (Mo), aluminum (Al), and nickel (Ni), are considered as hazardous wastes which will result in not only ecosystem damage but also squandering resource. Herein, a process featuring blank roasting-alkaline leaching is proposed to recover spent HDS catalyst. During roasting, low-valence compounds convert to high-valence oxides which can be leached out by NaOH solution. Afterwards, leaching solution is subjected to crystallization to separate metals. The results show that for samples roasted at 650 oC, 97% V, 96% Mo, and 88% Al are leached out at optimal condition; for samples roasted at 1000 oC, selective leaching of 91% V and 96% Mo respectively, are realized, with negligible Al being dissolved. NiO is insoluble in strong alkali leaving in residue. The advantages of this process are that first, the leaching of V, Mo, and Al can be manipulated by controlling roasting conditions, providing flexible process design. Second, leaching solution can be fully recycled. Finally, mild leaching condition and clean separation of V, Mo, and Al is achieved, proving fundamental information for peer researches to facilitate their future research on the development of more efficient and cleaner technologies.
Globally, fly ash (FA), generated in huge quantities from coal fired power plants is a problematic solid waste.
Utilization of FA as an ameliorant for improving soil quality has received a great deal of attention over the past
four decades, and many studies have been carried out worldwide. The silt-sized particles, low bulk density
(BD), higher water holding capacity (WHC), favorable pH, and significant presence of plant nutrients in FA,
make it a potential amendment for soils. The studies suggest enormous potential for the use of FA to improve
cultivable, degraded/waste land, mine soil, landfills, and also to reclaim abandoned ash ponds, for agriculture
and forestry. FA application improves the physical, chemical and biological qualities of soils to which it is applied.
However, in some cases, depending on the characteristics of FA, the release of trace elements and soluble salts
from FA to a soil–plant–human system could be a constraint. The effect is minimal in the case of weathered FA.
The findings reflected the heterogeneity of ash characteristics, soil types, and agro-climatic conditions, thus a
generalized conclusion on the impact of FA on plant species and soil quality is difficult. It is very important
that the application of FA to soil must be very specific depending on the properties of the FA and soil. A
considerable amount of research has been carried out to blend FA with varieties of organic and inorganic
materials, like lime, gypsum, red mud, animal manure, poultry manure, sewage sludge, composts, press mud,
vermicompost, biochar, bioinoculants, etc. Co-application of FA with these materials has much advantage:
enhanced nutrient availability, decreased bioavailability of toxic metals, pH buffering, organic matter addition,
microbial stimulation, overall improvement in the general health of the soil, etc. The performance of FA blending
with organic and inorganic materials is better than FA alone treatments. Farm manure was found to be the most
promising amendment used along with FA. While using FA in agriculture as a soil ameliorant, it is better to seek
the locally available fitting blend materials for exploiting the benefits fromtheir synergistic interaction. However,
continuous research in parallel for long durations to dispel apprehension, if any, is desirable under well defined
regulatory measures.
Petroleum refining is one of the largest manufacturing and processing industries in the world. In the U.S there were 185 refineries in 1992. Some of the refining operations require the use of catalysts that contain mainly nickel, cobalt, and molybdenum on an alumina matrix. Upon deactivation, spent catalysts also contain vanadium, sulfur and minor impurities such as phosphorous and arsenic. Gulf Chemical and Metallurgical Corporation (GCMC) operates an integrated facility for metals recovery from spent hydroprocessing catalysts in Freeport, Texas. The recovered metals are directly reused for the manufacture of catalysts and production of ferroalloys. Fused aluminum oxide is recycled to the ceramic and refractory industries. This paper will discuss GCMC = s contribution to the recovery and reuse of metals contained in spent catalysts over the last fifty years.
One approach to increasing the sustainability of concrete construction is to replace a significant portion of the ordinary portland cement (OPC) with a supplementary cementitious material, such as fly ash. This paper presents mixture proportions and measured properties for a series of six high-volume fly ash (HVFA) concretes, five containing a ternary component of a fine limestone powder, with cement replacement levels of 40% or 60% by volume, targeting moderate slump (150 mm) applications. Special emphasis is given to electrical resistivity measurements, comparing measurements conducted in a uniaxial vs. a surface configuration, and assessing the capability of measurements of the bulk resistance of the fresh concrete to anticipate setting times in these HVFA mixtures. The degree to which relationships exist between compressive strength and either cumulative heat release or uniaxial resistivity are presented. In general, ternary blend HVFA concretes can be formulated to provide acceptable strengths at both early ages and over the longer term, with an increased resistivity that implies an enhanced durability and increased service life. However, to achieve moderate slumps at the requisite lower water-to-cementitious material ratios, high dosages of high-range water-reducing admixtures (HWRA) will likely be required, which can negatively impact early-age properties (e.g., setting time and 1 d strengths). Thus, optimum mixture proportioning will require the careful selection and evaluation of the available HRWRA products, both individually and in potential combinations. Finally, another viable route to reducing cement content is to increase the aggregate volume fraction, as demonstrated by the OPC control concretes investigated in this study where aggregate volume fraction was increased from 70% to 72.5%, concurrently achieving a 10% reduction in cement content. In the ternary blend HVFA mixtures, further increases to 75% aggregates were possible, resulting in overall cement reductions (per unit volume of concrete) of between 45% and 63%.
The extraction properties of metallic elements from the spent refinery processing catalyst were examined under citric acid leaching conditions. Different temperatures were tested for the extraction experiments and 80 °C was found to be most effective for metal extraction from the spent refinery processing catalyst. Compared to room condition, citric acid leaching treatment with 80 °C accelerated the dissolution of the catalyst waste solid, thus promoted the reaction of acid with hazardous metals such as Al, Ni, Mo. Furthermore, the optimum hydrothermal treatment temperature, time and liquid/solid ratio were 80 °C, 10 h and 8:1 (ml: g), respectively.
Nowadays bioleaching occupies an increasingly important place among the available mining technologies. Today bioleaching is no longer a promising technology but an actual economical alternative for treating specific mineral ores. An important number of the current large-scale bioleaching operations are located in developing countries. This situation is determined by the fact that several developing countries have significant mineral reserves and by the characteristics of bioleaching that makes this technique especially suitable for developing countries because of its simplicity and low capital cost requirement. The current situation of commercial-size bioleaching operations and ongoing projects in developing countries is presented and discussed with especial reference to copper and gold mining. It is concluded that this technology can significantly contribute to the economic and social development of these countries.
Driven by increasingly stringent environment legislation and the need to maximize profitability, refiners' use of ex-situ catalyst regeneration continues to grow. Refiners are adding hydroprocessing capacity to meet lower product sulfur specifications, and much of this additional catalyst can potentially be regenerated. Regeneration helps refiners maximize the value of catalyst by allowing them to avoid disposal costs, generate revenue from spent catalyst, and reduce cost of the next catalyst loads. when catalyst is dumped from a unit, samples of the spent catalyst can be analyzed to determine which portion is a candidate for regeneration.
The various process options available to recover vanadium from spent dehydrosulphurisation catalysts, sulphuric acid catalysts, and alumina sludge residues from the Bayer Process are reviewed, and the fate of other metal impurities such as Mo, Ni, Co, Al and Fe are considered. Most processes give an impure V2O5 product, but selective solvent extraction of vanadium from the impure leach solution allows high purity product to be obtained. A comparison is made between the D2EHPA and Amine extractants with regard to the vanadium species and other metals extracted. The results of studies with tertiary and quaternary amines in acidic media are reported, and the relative performance of quaternary amines in extracting a range of vanadium(V) anionic species between pH 6–13 is presented. It is shown that quaternary amines offer the greatest flexibility for treating acidic, neutral, or alkaline liquors depending on the process of choice.
The sulfuric acid leaching of spent hydrodesulfurization catalysts yields an acidic solution rich in rare metals such as molybdenum, vanadium, cobalt and nickel in addition to aluminum. For the purpose of separating and recovering the rare metals from the solution, basic solvent extraction characteristics of the metals involved with commercially available acidic organophosphorus reagents, as well as aliphatic alpha-hydroxyoxime from sulfuric acid media were investigated.
Cotter Corp. 's new 60-tpd spent-catalyst processing plant that recovers molybdenum, nickel, tungsten and vanadium products from spent catalysts is described. The company entered the business as a sideline to its main activity - the mining and processing of uranium ore. The spent-catalyst plant contains ammonium carbonate and sodium hydroxide leach circuits to provide the versatility required to recover various metals from a variety of spent catalysts.
This contribution is an attempt to examine most important problems, at a fundamental level, determining the future development of hydrotreating catalysts and further progresses in the corresponding processes. The discussion is centered on the sulfided catalysts associating molybdenum (or tungsten) with cobalt, nickel or iron. A first section deals with characterization. Much progress has been made with respect to the oxide precursor form. Recent advances concerning the activated (sulfided) form are impressive. These advances are outlined. Additional tools, possibly those depending on the adsorption of probe molecules, must be developed for deciding on critical issues. One such issue is whether activity is due to a phase associating the Group VIII and the Group VI metal (so called "Co-Mo-S" and similar phases), to special cobalt sulfides, to contacts between Group VI and Group VIII sulfides (remote control) or to other causes. A second section deals with preparation, activation, ageing and regeneration. Except for the first item, only scarce data have been published. The very short discussion corresponding to this section recalls recent advances in the understanding of activation and simulated regeneration, indicates the areas where more knowledge is needed, and points to results having direct bearing on fundamental issues. The third section is devoted to mechanisms. Kinetic data are not discussed. New data and speculations on the molecular mechanism of adsorption and hydrogenolysis of heteroatom containing molecules are presented, and their possible consequences discussed. The connections of these mechanisms with the real nature of the active catalyst are examined, with respect to structure of the active center, supply of hydrogen to the active center and cooperation between Group VI and Group VIII elements.
Considering stringent environmental and safety regulations, metal recovery from spent catalysts is a more attractive option than landfilling. Metals such as Mo, Ni, Co, and V are highly valuable and are used extensively in the steel industry and in the manufacture of special alloys. They are usually manufactured from the ores and minerals containing them. Spent hydroprocessing catalysts could be used as a cheap source for these valuable metals. There are several studies that focus on recovery of Mo, Ni, V, and Co from the spent hydroprocessing catalysts. In addition, several companies are established for large-scale reclamation of metals and metal compounds from spent hydroprocessing catalysts. This chapter discusses reclaiming metal from spent hydroprocessing catalysts. It reviews the information available in the literature both on the laboratory studies and industrial scale processes for recovery of metals from spent hydroprocessing catalysts. Most of the studies on recovery of metals from spent hydroprocessing catalysts involve leaching with the solutions of both inorganic and organic agents. Leaching with the aid of a microorganism, i.e., bioleaching, is attracting attention as well. The dissolution of metals in water may also be enhanced by roasting spent catalysts with compounds containing alkali metals, such as sodium and potassium. Two-stage processes may employ both leaching and roasting. The volatilization or dissolution of metals of interest can be enhanced by chlorination. Attempts are made to develop novel methods, which could be competitive with conventional methods for metal reclamation.
Refiners have three options to deal with spent catalysts: regeneration, reclamation, or disposal. This article discusses the metals reclamation and landfill industries. To present an accurate picture of reclamation and disposal industries, major vendors and suppliers are mentioned in this article. Metal reclaimers use one of two methods: hydrometallurgy or pyrometallurgy. Hydrometallurgy dissolves the metals by leaching the catalyst with an acid or base. Pyrometallurgy uses a heat treatment, such as roasting or smelting, to separate the metals. In the U.S., there are two major nonprecious metals reclaimers: Gulf Chemical and Metallurgical Corp. (GCMC) and Cri-met. Both Cri-met and GCMC use hydrometallurgical processes for reclamation of hydrotreating and hydrorefining catalysts. Reclamation process recovers following metals from spent catalysts: molybdenum, vanadium, nickel, and cobalt. When regeneration and reclamation alternatives have been exhausted, spent catalyst can be sent to landfills.
The aqueous solutions of six organic agents were used for reclamation of metals from a spent NiMo/Al2O3 hydroprocessing catalyst which could not he regenerated for reuse. Experiments were conducted at 50°C using either an ultrasonic bath or agitation with magnetic stirrer. For most of the agents, the latter treatment gave a higher leaching efficiency. Leaching efficiency was similar for the decoked panicles as received and minus 60 mesh particles obtained by crushing the former. The following order in leaching efficiency was established among the six organic agents used: tartaric acid > citric acid ̃ glyoxylic acid ∼ lactic acid > glycolic acid > water > glyoxal. Tentative mechanism involving the ionization of agents, followed by complex formation with metal species and dissolution was proposed to describe the leaching process.
Due to rapid industrialization the demand for heavy metals is ever increasing, but the reserves of high-grade ores are diminishing. Therefore there is a need to explore alternative sources of heavy metals. The rapid industrialization generates a variety of industrial wastes. These industrial wastes possess toxic elements such as heavy metals. Improper disposal of these wastes becomes a key factor in metal contamination and thus when leached into atmosphere cause serious environmental problem. These metals exert wide variety of adverse effects on human being. Some of the metals have extremely long biological half-life that essentially makes it a cumulative toxin. Also some metals are carcinogenic in nature. Among the wastes, electronic scraps, medical waste, metal finishing industry waste, spent petroleum catalysts, battery wastes, fly ash etc., are some of the major industrially produced wastes. These solid wastes mostly contain Au, Ag, Ni, Mo, Co, Cu, Zn, and Cr like heavy metals in it. Hence these waste materials which are causing serious environmental problems, can act as potential source for heavy metals. In this sense these industrial wastes can act as artifitial ores. The valuable metals can be recovered from these industrial wastes. There are varieties of methods in use for recovery of heavy metals. These include pyrometallurgical, hydrometallurgical and bio-hydrometallurgical methods. Pyrometallurgical recovery consists of the thermal treatment of ores and metal containing wastes to bring about physical and chemical transformations. This enables recovery of valuable metals. Calcining, roasting, smelting and refining are the pyrometallurgical processes used for metal recovery. The hydrometallurgical recovery uses mainly the leaching process. It involves the use of aqueous solutions containing a lixiviant which is brought into contact with a material containing a valuable metal. Further the metals are concentrated and purified by using precipitation, cementation, solvent extraction and ion exchange. The metals are finally recovered in pure form by using electrolysis and precipitation methods. Biohydrometallurgy is one of the most promising and revolutionary biotechnologies. This technique exploits microbiological processes for recovery of heavy metal ions. In last few decades the concept of microbiological leaching have played a grate role to recover valuable metals from various sulfide minerals or low grade ores. Now the microbiological leaching process has been shifted for its application to recover valuable metals from the different industrial wastes. There are many microrganisms which play important role in recovery of heavy metals from industrial wastes. Among the bacteria Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans, and Sulfolobus sp., are well known for the bioleaching activity while Penicillium, and Aspergillus niger are some fungi those help in metal leaching process. The process of recovery makes sense only if the cost of recovery is much less than the value of the precious metal. The restrictions imposed on waste disposal and stringent environmental regulations demand eco-friendly technologies for metal recovery. This paper reports a review of number of industrial processes that generate metal containing waste and the various methods in use for recovery of metals from these wastes. This will help in selection of a proper method for recovery of heavy metals from industrial wastes.
Hydrotreating heavy oils produces catalysts that are contaminated with coke and with nickel, vanadium and iron. Regeneration may be possible but sooner or later irreversible deactivation occurs. Means of regenerating or disposing of spent catalysts are reviewed. Regeneration may or may not involve decoking, with selective removal of Ni, V and Fe being achieved by leaching with different reagents. Leaching of all metals from the spent catalyst may be achieved if disposal is required and the economic justification exists. The solid wastes must be encapsulated or stabilized before final disposal in order to meet environmental standards.
Since the early 1950s much of the world's crude oil and heavy fractions have been catalytically desulphurized using HydroDeSulphurization processes (HDS). The types of catalyst used in these processes contain in varying percentages cobalt oxide, between 2.5 and 3.0%, nickel oxide, 5.0% and molybdenum oxide, up to 12.0%. These are combined on an inert carrier consisting of aluminum oxide. Of the above total some 40% of the material is based on cobalt and 60% on nickel molybdenum catalysts.
Spent hydrodesulphurization (HDS) catalysts contain some amounts of rare metals such as molybdenum, vanadium, nickel, cobalt and so on. At present, some extent of molybdenum and vanadium is being recovered by leaching with hot water after roasting together with sodium carbonate at temperature above 650°C and then precipitating the latter as ammonium vanadate by adding ammonium chloride and subsequently the former as molybdenum hydroxide after pH adjustment. According to this method, all of nickel and cobalt in addition of small amount of molybdenum and vanadium remained in aluminum carrier and hence cannot be recovered. These waste carriers contaminated with these metals have not found any reuses and are being dumped; but, it is expected that in very near future it will become very difficult to find any places for the dump of these wastes in Japan.
The nature of the active phases and sites, the reaction mechanisms, and the role of additives and promoters are discussed in the light of new spectroscopic and kinetic results. The active phases in promoted Co-Mo (Ni-Mo) catalysts are the socalled Co-Mo-S (Ni-Mo-S) structures. A description of these structures is given. It is proposed that the Co edge atoms in Co-Mo-S are present in two types of sites having square and tetragonal pyramidal coordination, respectively. These represent the free and occupied sites which interconvert during a catalytic cycle. The chemical and catalytic properties of the sites associated with the active phases are influenced by many parameters and changes in these may, for example, give rise to either Type I or Type II Co-Mo-S structures with different catalytic properties. Also the presence of an additive like P influences the properties of the surface sites as revealed by infrared and Mössbauer spectroscopies and kinetic studies. Simultaneous hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and hydrogenation (HYD) studies have also yielded new insight. The results indicate that under typical reaction conditions the active sites are predominantly covered by atomic and not molecular species. Furthermore, in spite of the structural complexities it is found that for a given catalyst, it may often be sufficient to consider the HDS, HYD, and HDN reactions occurring on the same sites. This is in contrast to the conclusions from earlier studies. Infrared spectroscopy has also provided the first direct evidence for the existence of Brønsted acid sites in sulfided hydrotreating catalysts but the role of these sites in HDS, HDN, and HYD appears to be small. Based on the description of the active sites and their genesis, catalyst design criteria are discussed.
The recent U.S. Environmental Protection Agency's (EPA's) memorandum clarified that spent catalysts resulting from 'dual purpose' hydroprocessing reactors are hazardous waste. This article provides insight into the definitions in the EPA regulations that refiners must follow when determining how spent hydroprocessing catalysts should be classified.
A discussion covers the Type 2 catalysts, Ni-Mo KF848-STARS and Co-Mo KF757-STARS, which feature lower metal-support interaction that leads to a different sulfidation behavior, and the NEBULA catalyst, a novel hydroprocessing catalyst that allows refiners to produce ultra low sulfur diesel in most high-pressure units that have been designed for the production of 500 ppm S; performance of Type 2 catalysts; HDN activities of the catalysts; and the development of conventional hydroprocessing catalysts and the new catalyst generations, STARS and NEBULA.
Hydrotreating or hydroprocessing refers to a variety of catalytic hydrogenation processes which saturate unsaturated hydrocarbons and remove S, N, O and metals from different petroleum streams in a refinery. These processes represent some of the most important catalytic processes and the annual sales of hydrotreating catalysts represent close to 10% of the total world market for catalysts.
A fundamental kinetic framework is developed for deactivation by site coverage, coke growth and blockage in pores and networks of pores. Diffusional limitations are also accounted for. The methodology of kinetic studies of catalyst deactivation by coke formation is discussed by means of a number of practical examples. Finally, the effect of catalyst deactivation on the behavior of reactors is illustrated.
This paper presents the effect ultrafine fly ash (UFFA) on compressive strength and durability properties of concretes containing high volume class F fly ash as partial replacement of cement. The compressive strengths are measured at 3, 7, 28, 56 and 90 days, whereas the durability properties are measured at 28 and 90 days. Chloride induced corrosion, water sorptivity, volume of permeable voids, chloride ion penetration, chloride diffusivity and porosity of above concretes are measured in durability properties. Microstructural analysis in terms of thermogravimetric analysis (TGA) is also conducted to identify the reaction phases of calcium hydroxide in the HVFA matrix containing UFFA. Results show that the addition of 8 wt.% UFFA significantly improved the early age as well as later age compressive strengths of ordinary and HVFA concretes. All above measured durability properties of HVFA concretes are also improved and in most cases the HVFA concrete containing 32% fly ash and 8% UFFA exhibited superior durability properties than ordinary concrete containing 100% cement. The results also indicate the effectiveness of UFFA in producing high packing density and in accelerating the pozzolanic activity to produce more C–S–H gel by consuming calcium hydroxide (CH) in HVFA concretes.
Large quantities of solid catalysts are routinely used in many chemical industries especially in petroleum refining and petrochemical industries. Solid catalysts contain metals, metal oxides or sulfides, and require replacement after two or three years of operation. Therefore, large quantities of spent catalysts are generated as solid wastes every year. Because of their hazardous nature and toxic chemical products, there are stringent environmental regulations for discarded spent catalysts. The recovery of metals from these catalysts is also an important economic aspect as most of these catalysts are supported, usually on alumina/silica with varying percent of metal. Bio-hydrometallurgical approaches are more economical and environmentally friendly than physicochemical metal-extraction processes. In this paper, the information available on the bioleaching fundamentals of spent catalyst wastes, as well as a focus on recent developments, is reviewed in detail.
The separation techniques of vanadium and molybdenum were summarized, and a new method of removal V(V) from Mo(VI) by adsorption with chelate resin was presented. Nine kinds of chelate resins were used to investigate the adsorbent capability of V(V) in ammonium molybdate solution with static method. The test results show that DDAS, CUW and CW-2 resins can easily adsorb V(V) in ammonium molybdate solution, but hardly adsorb Mo(VI). The dynamic experimental results show more than 99.5% of V(V) can be adsorbed, and the adsorption rate of Mo(VI) is less than 0.27% at 294–296 K for 60 min at pH 7.42–8.02. The mass ratio of V to Mo decreases to l/5 0000 in the effluent from ½55 in the initial solution. The loaded resin can be desorbed by 5% NH3·H2O solution, and the vanadium desorption rate can reach 99.6%. The max concentration of vanadium in desorbed solution can reach 20 g/L, while the concentration of molybdenum is less than 0.8 g/L.
In this paper, the effects of fluorine and phosphorus on the physical and chemical properties of Ni–Mo/Al2O3 catalysts and the hydrodenitrogenation (HDN) activity of quinoline were investigated. The acidity, pore structure, and dispersion of Mo of the catalysts were analyzed with TG-DTA, BET, and XRD techniques. The activities of hydrodenitrogenation and hydrogenation of the catalysts were investigated using hydrogenation of quinoline at high pressure in a micro-reactor. Experimental results verified that phosphorus can promote the formation of moderate and strong acidic sites, the dispersion of Mo, and the formation of the active phases; therefore, the hydrogenation activity of aromatic rings and the hydrogenolysis activity of C–N bonds increase. The hydrogenation and hydrogenolysis accelerate each other, which results in the increase of HDN activity. It is concluded that phosphorus is a promoter for HDN activity of the Ni–Mo/Al2O3 catalysts. Fluorine can promote the formation of weak and moderate acidic sites and the dispersion of Mo, but inhibit the formation of the active phases. Therefore, the hydrogenation activity of aromatic rings and the hydrogenolysis activity of C–N bonds decrease, which results in the decrease of HDN activity. It is concluded that fluorine is not a promoter for HDN activity of the Ni–Mo/Al2O3 catalysts. The possible promoting mechanism of fluorine and phosphorus for the Ni–Mo/Al2O3 catalyst is put forward and discussed.
Various methods for separation, purification and recovery of molybdenum and vanadium from leach solutions of spent catalysts are reviewed. The main methods include sulphide precipitation, ammonium salt precipitation, carbon absorption, ion exchange and solvent extraction. These methods are briefly compared and assessed for both purification of leach solutions and recovery of molybdenum and vanadium from the solutions in terms of their selectivity, efficiency and product quality. The strategies for recovery of other valuable metals including nickel and cobalt are also reviewed and discussed.Among these methods, precipitation offers low cost and simple operation, however, high purities (> 99%) of products of molybdenum and vanadium cannot be achieved. The loading capacities of activated carbon for molybdenum and vanadium are relatively low, resulting in no industrial application of this technology in the separation of molybdenum and vanadium. Ion exchange offers a useful means for almost complete separation of molybdenum and vanadium and for production of their high purity products, although the scale of application of ion exchange in industry is limited. Solvent extraction is highly selective for separation and recovery of molybdenum and vanadium, and is the most promising method recommended for future research and development.
Coal fly ash is generated during the combustion of coal for energy production. Its utilisation as an industrial by-product has received a great deal of attention over the past two decades as more sustainable solutions to waste problems have been sought. The present paper reviews the potential applications for coal fly ash as a raw material: as a soil amelioration agent in agriculture, in the manufacture of glass and ceramics, in the production of zeolites, in the formation of mesoporous materials, in the synthesis of geopolymers, for use as catalysts and catalyst supports, as an adsorbent for gases and waste water processes, and for the extraction of metals. The review then analyses the impact that a multi-stage process could have by examining the technology capable of a series of separations to produce hollow microspheres, enriched carbon, magnetic spheres, fine ash product, and coarse ash product. The applications for these coal fly ash derived products were also reviewed. It was found that there is significant potential for the increased utilisation of coal fly ash both in its raw and refined state. It is suggested that, by processing the coal fly ash, the scope for creating new industrial synergies is enhanced.
The hydrodesulfurization (HDS) of thiophene and its derivatives by Mo-based catalysts shows significant economic benefits in crude oil processing and refining. Several Mo-based catalysts have been successfully used for HDS reaction despite of unclear catalytic mechanism. Thereby we use in situ FT-IR technique to investigate the adsorption of thiophene on the surface of supported and dispersed sulfided Mo catalysts. The results demonstrate that thiophene can be adsorbed on the catalyst surface through coordination of S atom, CC and CC with the unsaturated Mod+ sites located on the edge planes of MoS2-like structures, forming four different complexes. These adsorption manners were also proved by theoretical calculation with the density functional method (DFT). The calculated binding energy of η2(S) complex is larger than other complexes, suggesting that thiophene preferred to being adsorbed on the catalyst surface through the coordination of CC with unsaturated Mod+ sites. The formation of coordinated complexes can decrease the aromaticity of thiophene ring and weaken CS bond, which could promote the HDS reaction.