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Abstract
Solid base catalysts used in the transesterification for biodiesel production can simplify the technological processes, especially the separation process of products. By screening metal oxides, calcium oxide was found to be a potential catalyst for the transesterification of rapeseed oil. Impregnating calcium acetate solution onto MgO carrier and calcining the impregnated sample obtained a CaO/MgO catalyst containing 16.5% (mass) of calcium oxide, which exhibited a high activity in the transesterification reaction. By using this catalyst, under the condition of 64.5°C, a methanol/oil molar ratio of 18:1 and a catalyst dosage of 2%, oil conversion reached 92% in 3.5h, which was close to the oil conversion using the traditional NaOH. Furthermore, the solid catalysts obtained were characterized with XRD, AAS, XPS and CO 2-TPD. The results showed that the basicity of the catalysts greatly affected their activities. Properly selecting the carrier, precursor and Ca-loading could increase the strong basic sites, and therefore increase their catalytic activity.
... Some disadvantages associated with homogeneous alkali catalysts, such as costly separation of the catalyst from the reaction mixture, have inspired the development of heterogeneous solid catalysts for biodiesel production, and solid alkali catalysts including mainly alkali metal oxides, alkaline-earth metal oxides, hydrotalcite and hydrotalcite-like solid alkali have thus been developed [18,19]. In general, alkali metal oxides and alkaline-earth metal oxides are hygroscopic, which leads to costly separation. ...
... However, these types of solid alkali catalysts are easily poisoned by H 2 O and CO 2 . Researchers have also investigated activated carbon, MgO, CaO, ZrO 2 and TiO 2 as the solid alkali catalysts for biodiesel production [18][19][20]. ...
At present, traditional fossil fuels are used predominantly in China, presenting the country with challenges that include sustainable energy supply, energy efficiency improvement, and reduction of greenhouse gas emissions. In 2007, China issued The Strategic Plan of the Mid-and-Long Term Development of Renewable Energy, which aims to increase the share of clean energy in the country's energy consumption to 15% by 2020 from only 7.5% in 2005. Biodiesel, an important renewable fuel with significant advantages over fossil diesel, has attracted great attention in the USA and European countries. However, biodiesel is still in its infancy in China, although its future is promising. This chapter reviews biodiesel production from conventional feedstocks in the country, including feedstock supply and state of the art technologies for the transesterification reaction through which biodiesel is made, particularly the enzymatic catalytic process developed by Chinese scientists. Finally, the constraints and perspectives for China's biodiesel development are highlighted.
... CaO-based catalysts are usually employed in the powder form in batch reactors under intensive agitation. However, fine CaO powder causes the problem in separation from the final product [5]. When larger CaO particles are applied, then intensive agitation results in http://dx.doi.org/10.1016/j.fuel.2015.03.057 0016-2361/Ó 2015 Elsevier Ltd. ...
... Transesterification or alcoholysis is the chemical reaction that involves triglyceride and alcohol in the presence of a catalyst to form esters with glycerol as the backbone [132]. Catalyst is usually used to enhance the reaction rate so that the reaction can be completed in a relatively shorter reaction time [133,134]. ...
The demand for petroleum has risen rapidly due to increasing industrialization and modernization of the world. The limited reserve of the fossil fuels is also dwindling alongside escalation in the prices. The threats from these and food insecurity are, however, drawing the attention of researchers for alternative fuel which can be produced from renewable feedstocks. Biodiesel as the most promising alternate is currently produced from conventionally grown edible plant oils such as rapeseed, soybean, sunflower and palm. The use of the edible oils is worsening the current competition of oil for food and for fuel. Focus on the use of non-edible resources is presently directed to jatropha, mahua, pongamia, calophyllum tobacco, cotton oil, etc. Discrepancies between the expectation and realities regarding these non-edible oils are necessitating efforts for diversification of the feedstocks to resources that could guarantee energy production without affecting food security. Neem, karanja, rubber and jatropha are evergreen multipurpose non-edible plants that are widely available and can be grown in diverse socio-economic and environmental conditions. These plants are described as golden trees that have multiple uses such as for fuels, medicines, dyes, ornamentals, feeds, soil enrichment, afforestation, etc. This study was therefore undertaken to explore the multipurpose of these four non-edible tree plants. Among the highlights of this expatiate review include oil as feedstock for biodiesel, the need for non-edible feedstocks, neem, karanja, rubber, jatropha and their value chains, methods of modifying oil to biodiesel, factors affecting biodiesel production, application of the selected non-edible seed biodiesels to engines for performance and emission characteristics and the outlook.
... Nevertheless, as CaO exists in the reaction mixture in a form of suspensoid due to its poor mechanical strength, resulting in separation problems of catalyst from biodiesel products; thus, supporting CaO onto carriers was found to improve the performance of CaO catalysts [26][27][28].Transesterification of soybean oil with a CaO/mesoporous silica catalyst rendered a maximum FAME yield of 95.2% but required considerably higher reaction time of 8 h [29]. In the past, Al 2 O 3 supported CaO catalyst had been developed using reagent grade chemicals for production of biodiesel from microalga"s lipid [30] and palm oil [31][32][33]. ...
An efficient and inexpensive calcium oxide-calcium aluminate solid base catalyst has been developed for biodiesel synthesis from mustard oil (MO) of Indian origin (Brassica Nigra). The active metal precursor Ca (OH) 2 of the catalyst has been economically derived through calcination of waste duck eggshell and the high activity supported catalyst has been prepared through co-precipitation method. X-ray diffraction (XRD), scanning electron microscope (SEM), low temperature N 2 adsorption-desorption (BET) and Mercury Intrusion Porosimetry (MIP) studies demonstrate the existence of CaO and calcium aluminate crystalline phases with rod like macroporous particles having specific surface area of 2.909 m 2 /g, pore volume of 0.55 cc/g and a basicity of 12.6 mmol HCl/g catalyst. The high catalytic activity has been demonstrated through transesterification of MO for synthesis of biodiesel. A three factor-three level face centred central composite design (FCCD) has been used to determine the effects of process parameters on fatty acid methyl ester (FAME) yield. Optimal parametric values were CaO loading of 30 wt.%, calcination temperature of 990 ° C and 3.82 wt.% catalyst concentration which resulted a remarkably high (i.e. maximum 99.58%) FAME yield evaluated using response surface methodology (RSM). The fuel properties of prepared biodiesel have been found to comply with ASTM/ EN standards.
Bio-oil from fast pyrolysis of biomass is considered as a potential drop-in fuel and a source of chemicals. Nonetheless, the high acid content in bio-oil challenges storage and further downstream processes. The current study investigated a combination of esterification and neutralization reactions for intrinsic acids in bio-oil by treating with MeOH in presence of CaO. CaO can have two roles: as a catalyst in esterification and as an alkaline agent in neutralization. Even though methanol reduced the acidity of bio-oil, the presence of CaO enhanced the reduction. This is because of a combined effect of esterification and neutralization reactions. 98% of acids in the bio-oil was converted in the presence of 5 wt% of CaO and MeOH/bio-oil ratio of 0.5. Further analysis showed that neutralization reaction was dominant over esterification for acid conversion.
Ca/Al solid basic catalysts were prepared by co-precipitation method and used in the synthesis of biodiesel from rapeseed oil; the effect of preparation conditions such as precipitant selection, mole ratio of calcium to aluminum, precipitation temperature, pH value, aging temperature and time, and calcination temperature on their catalytic activity were investigated. Through orthogonal tests, the optimal conditions to prepare catalyst precursor are obtained as Ca/Al=3, NaOH as precipitant, precipitation temperature of 60°C, pH value of 10, and aging at 90°C for 18 h. Under the optimal conditions, the catalyst precursor obtained is in the form of Ca 4Al 2O 6(NO 3) 2 · 10H 2O crystal. After calcination at 300°C for 2 h in N 2 atmosphere, Ca/Al mixed oxide is then highly dispersed on the catalyst surface with a pH value of above 26.5. The catalyst exhibits excellent activity in transesterification of rapeseed oil with methanol; the conversion of rapeseed oil and selectivity to fatty acid methyl ester reach 95% and 95.9%, respectively.
A novel solid base catalyst, CaO/MgO/Fe3O4 with magnetism used for production of clean biodiesel, was prepared and characterized by X-ray diffraction, transmission electron microscope, infrared spectrum and magnetism analysis. The catalytic activities of the fresh and the reused catalysts for the transesterification of peanut oil with methanol to produce biodiesel were investigated. The magnetic support of MgO/Fe3O4 with MgO loading of 5% was obtained by the magnetic matrix Fe3O4 dipped in Mg(Ac)2 aqueous solution and then calcined at 600°C in N2. And CaO/MgO/Fe3O4 with CaO loading of 10% was prepared by MgO/Fe3O4 impregnated in Ca(Ac)2 aqueous solution and further calcined at 700°C in N2. The particle of CaO/MgO/Fe3O4 was shell-core structure with the core mean diameter of 35 nm. The results show that CaO/MgO/Fe3O4 has higher catalytic activity for transesterification reaction and could be separated easily from the reaction products in magnetic field. Both the conversion of peanut oil and recovery of the catalyst are above 90% under the conditions of atmospheric pressure, 65°C for 2 h, methanol/oil mol ratio of 12, and catalyst dosage (catalyst/oil) of 10%. The falling off of CaO from CaO/MgO/Fe3O4 during stirring reaction process was speculated as one of the reasons for the lower activity of the reused catalyst.
The nano-structured KF/γ-Al2O3-catalyzed synthesis of biodiesel was performed in ultrasonic irradiation. Effects of experimental parameters including ultrasonic power density, molar ratio of methanol to soybean oil, catalyst amount, reaction temperature and time on the transesterification of soybean oil and methanol were investigated. The fresh and used catalysts were characterized by means of XRD, TEM and BET. The results indicate that increasing the ultrasonic power density causes the increase in the methyl esters concentration of the transesterification. The maximum concentration of methyl esters is 98.70% under the following optimized conditions: ultrasonic power density 53.3 W/L; molar ratio of methanol to soybean oil 6:1; mass ratio of catalyst to soybean oil 3%; reaction temperature 45°C and reaction time 35 min. In comparison to the mechanical stirring, the ultrasonic irradiation allows the significant reduction of the amounts of KF/γ-Al2O3 and methanol and the time requires for reaching equilibrium. The structure of nano KF/γ-Al2O3 surface does not change, but the specific surface area of the nano-catalyst greatly reduces from 60.34 m2/g to 37.26 m2/g after transesterification of soybean oil and methanol in the ultrasound field.
In order to optimize the ultrasound-assisted corn oil biodiesel transesterification process conditions, factors four through five levels of orthogonal test to optimize their processes, the findings indicate that ultrasound-assisted transesterification of corn oil biodiesel optimum conditions : 1:11 molar ratio of methanol to oil, corn oil catalyst was 11%, the reaction temperature is 90 °C, reaction time was 50min, ultrasonic power 360W, under these conditions, the measured ratio of the average of the transesterification 91.85 %. Relative to conventional preparation methods, the method is simple, rapid, saving solvent consumption and other advantages.
Africa is a continent full of untapped natural resources ranging from biodiversity to vast water bodies but faced with food and energy crises. Prices of fuel are also escalating. With researchers and experts scrambling for the solution, biodiesel from vegetable oil will receive more attention. But the edible feedstock as the obvious cheapest choice will not be sustainable enough for the increasing energy and food demand; hence, there is a need for guaranteed feedstock. This study was therefore undertaken to explore feedstock that would not be suitable for food but useful for biodiesel in Africa. Among the highlight areas of the study include current energy situation in Africa, technologies of biodiesel production, current state of biodiesel in Africa, driving forces for increase in biodiesel production, current existing problems of biodiesel commercialization, potential benefits of biodiesel processes, need for non-edible oil plants, potential non-edible biodiesel feedstock, biology, distribution and chemistry of the selected non-edible oil plants. The study also throws light on the implication of biodiesel on the environment and the outlook. From the study, the use of non-edible oils can be guaranteed as sustainable feedstock for biodiesel since most of the non-edible plants can be grown on wastelands to reclaim them, not compete with food crops for limited lands, are relatively cheap, available and offer similar or even higher yields of biodiesel and fuel properties as the edibles. Developing biodiesel industry in Africa can help curb the high rate of unemployment through job creation as well as increase in income level of the rural populace. Weaning African economies from oil import dependencies could also be an economic achievement. It can be deduced from the study that there are promising non-edible oil resources in the system for biodiesel industrialization in Africa.
A new solid base catalyst containing Ca12Al14O33 and CaO was prepared by chemical synthesis method and was used in the transesterification of rapeseed oil with methanol to produce biodiesel. The catalyst was characterized by Hammett indicators, X-ray diffraction (XRD), infrared spectroscopy (IR), Brunauer–Emmett–Teller (BET) and scanning electron microscopy (SEM), separately. The effect of various factors was investigated to optimize the reaction conditions. The results showed that the ME (methyl ester) content reached 90% after reacting for 3 h at 65 °C, with a methanol/oil molar ratio of 15:1, the amount of catalyst of 6 wt.% and the stirring rate of 270 rpm. Moreover, the catalyst could be used repeatedly for at least 7 cycles with the ME content over 87%, due to its high stability. In particular, this solid base catalyst can be separated from reaction system effectively and easily, as it is insoluble in both methanol and methyl esters, which may provide significant benefits for developing an environmentally benign and continuous process for synthesizing biodiesel.
Nanometer magnetic solid base catalysts were prepared by loading CaO on Fe3O4 with Na2CO3 and NaOH as precipitator, respectively. The optimum conditions for preparation of this catalyst were investigated. The influence of the proportion of Ca2+ to Fe3O4 on the catalytic performance has been studied. The catalyst with highest catalytic activity has been obtained when the proportion of Ca2+ to Fe3O4 is 7:1; the catalytic activity of the catalyst calcined from Ca(OH)2 to Fe3O4 is better than that calcined from CaCO3 to Fe3O4; under the conditions of methanol/oil molar ratio of 15:1, catalyst dosage of 2wt% and temperature of 70°C, the biodiesel yield reaches to 95% in 80min, even to 99% finally. The catalytic activity and recovery rate of the nanometer magnetic solid base catalysts are much better than those of CaO. Calcination temperature was determined by differential thermogravimetric analysis. Ca2Fe2O5, a kind of new metal multiple oxide, was found in the catalyst through X-ray diffraction. At the end, these catalysts were characterized by scanning electronic microscope (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM).
A solid Ca/Al composite oxide-based alkaline catalyst containing Ca(12)Al(14)O(33) and CaO was prepared by chemical synthesis and thermal activation from sodium aluminate solution and calcium hydroxide emulsion. The effect of calcination temperatures ranging from 120°C to 1000°C on activity of the catalyst was investigated. The catalyst calcined at 600°C showed the highest activity with >94% yield of fatty acid methyl esters (i.e. biodiesel) when applied to the transesterification of rapeseed oil at a methanol:oil molar ratio of 15:1 at 65°C for 3h. Structure and properties of the catalyst were studied and the characterizations with XRD, TGA, FTIR, BET, and SEM demonstrated that the performance of the catalyst was closely related to its specific surface area and crystalline structure. In particular, the generation of crystalline Ca(12)Al(14)O(33) improved the catalytic activity due its synergistic effect with CaO.
Supported CaO/MgO catalysts were used as the catalyst of the transesterification of rapeseed oil with methanol. The supported catalyst showed a higher activity than pure CaO and was easily separated from the product mixture. The results of comparative experiments and catalyst characterization, such as XRD, CO 2 -TPD, BET, and AAS, showed that the activity of CaO catalysts is associated with their alkalinity. The preparation method of this catalyst was optimized, and furthermore, the reaction parameters were investigated. With the CaO/ MgO catalyst so obtained, the conversion of rapeseed oil reached 92% at 64.5 °C. The supported basic catalyst was found to be easily contaminated by the gaseous poisons in air, such as O 2 , CO 2 , and H 2 O, and as a result, a thermal treatment was required before the reaction to activate the catalyst.
Biodiesel is a green renewable energy resource. The current status of the development of biodiesel industry in the western countries and in China are presented. Topics for discussion, including to set up stable and reliable raw material based, to adopt a suitable production scale, to initiate relating procedures and criteria of biodiesel to enter the market to try out some appropriate policies, to develop advanced technologies, etc., are proposed to promote the development of China's biodiesel industry.
Methyl esters were produced by trans-esterification of cottonseed oil with methanol, in the presence of a homogeneous catalyst (KOH). A kinetic model was established by taking three consecutive and reversible reactions into consideration. Rate constants were determined for each reaction by the Runge-Kutta method with optimization. The corresponding values of frequency factor and activation energy were then obtained based on the Arrhenius' law for all forward and reverse reactions under different experimental conditions.