Saeed Sahebdelfar's research while affiliated with Petrochemical Research & Technology Company and other places

Publications (88)

Article
Full-text available
Pd–Ag/Al2O3 catalysts (Pd = 0.03 wt% with Ag = 0.18 wt% in bimetallic samples) were prepared by sequential impregnation using acidic and basic colloidal oxide solutions. The catalysts were evaluated for selective hydrogenation of acetylene to ethylene (T = 60 °C, p = 10 bar, H2/C2H2 = 1.5 mol/mol, GHSV = 4000 h⁻¹). The colloidal solutions were char...
Article
The kinetics of deactivation of γ-alumina catalyst in dehydration of methanol to dimethyl ether (DME) was studied using integral method of analysis. A power-law rate expression was used for dehydration reaction and an independent kinetics for catalyst deactivation. Catalytic test runs were performed in a fixed-bed integral reactor in the temperatur...
Article
Despite its bad reputation as a greenhouse gas and pollutant, carbon dioxide can be viewed as a renewable, non-toxic and cheap feedstock for chemical synthesis. The chemical utilization of CO2 not only could reduce greenhouse gas emissions, but also saves the fossil fuels resources. In this work, the chemical conversions relevant to large-scale uti...
Article
A series of Pd/γ-Al2O3 catalysts were prepared by wet impregnation method at different pH and time. The effect of metal distribution and dispersion on the catalyst reducibility in liquid-phase hydrogenation of olefins was studied. The samples were characterized by BET, XRD, ICP, FESEM, CO-chemisorption and H2-TPR techniques. Liquid-phase hydrogenat...
Article
Full-text available
The complete saturation of commercial olefin-containing (3.3 mol%) C4 stream over Pd/γ-Al2O3 catalysts was studied. The catalysts were prepared by wet impregnation of the support using acidified PdCl2 solutions. The effect of different preparation parameters such as HCl/PdCl2 ratio in impregnation solution, impregnation time and solution volume on...
Chapter
The depletion of fossil fuel reserves together with CO2 emission concerns have promoted worldwide search foralternative renewable and sustainable feedstocks for the production of chemicals and fuels. Lignocellulosicbiomass has good potentials because of its abundance and relatively low cost. The chemical conversion ofbiomass to commodity products i...
Article
Triply (Al, Ca and K) promoted wustite-based iron catalyst was prepared and compared with a similarly prepared magnetite catalyst for textural properties and performance in ammonia synthesis. The catalysts were synthesized by fusion method using Fe3O4 and metallic iron with similar nominal loading of promoters in both catalysts. The samples were ch...
Article
Full-text available
The adsorption of hexachloroplatinic acid on Sn-impregnated γ-alumina support in the presence of the competitive chloride ion, as a step in preparation of multi-metallic Pt-based catalyst (such as Pt–Sn/Al2O3), was studied. The transient adsorption data were obtained by studying the impregnation of Sn/Al2O3 with H2PtCl6 in an external recycle packe...
Article
The non-oxidative aromatization of methane was studied over M-Zn/HZSM-5 (M = La, Co, Pd, and Pt) catalysts using propane as a co-reactant. The catalysts were characterized by BET, SEM, NH3-TPD, and XRD techniques. Catalytic tests were performed in a fixed-bed reactor at 823 K using a mixture of methane, propane, and nitrogen with ratio of 6/1/1.3,...
Article
The thermodynamic equilibrium of gas-phase deoxygenation of propionic acid was studied over a wide range of reaction conditions (T=200–600 ºC, P=1–10 bar and H2/acid=0–10 mol/mol) using non-stoichiometric equilibrium models. The effect of catalyst type on equilibrium composition was incorporated by applying different combinations of the reactions i...
Article
The selective catalytic reduction (SCR) of nitrogen oxides on M/ZSM-5 (M = Cu, Ni, Co) catalysts was investigated. The catalysts were prepared using hydrothermal impregnation of the metal chlorides and nitrates on ZSM-5. The catalysts were characterized by nitrogen absorption/desorption, X-ray diffraction, Fourier transform infrared (FTIR) spectros...
Article
The catalytic selective hydrogenation of multiunsaturated hydrocarbons, especially in pyrolysis products, to corresponding mono-olefins is a widely exploited way for the large-scale production of polymer-grade olefins as well as fuel upgrading. Thermodynamic and/or kinetic parameters could be effective for selective operation. The latter is primari...
Article
Hierarchical SAPO-34 was synthesized hydrothermally using carbon nanotube as hard template and modified with Co and Ni by isomorphous substitution and impregnation methods. The prepared catalysts were characterized by XRD, SEM, TEM, XRF, UV–vis, NH3-TPD, H2-TPR, FTIR and N2 physisorption measurements and their catalytic performance was evaluated fo...
Article
The deactivation of a Pd-Ag/α-Al2O3 catalyst (2.5 mm in diameter, containing 0.03 wt.% Pd and 0.18 wt.% Ag) with egg-shell distribution was studied for acetylene selective hydrogenation. The reaction was performed in a fixed bed reactor using C2H2/C2H4/H2 feed mixture (1:67.5:1.5 molar ratio). The long-term deactivation behaviour of the catalyst wa...
Article
Ternary Cu/ZnO/Al2O3 methanol synthesis catalysts were synthesized by co-precipitation of copper and zinc hydroxycarbonates in the presence of various aluminum hydrous oxide sol preparation methods from sodium aluminate and aluminum nitrate as aluminum oxide sources. The catalysts were characterized at various stages of preparation by nitrogen adso...
Article
Crystalline silicoaluminophosphate of the CHA framework type (SAPO-34) with a hierarchical pore structure was hydrothermally synthesized using carbon nanotube as the mesopore template and TEAOH and/or morpholine as structure directing agents. The synthesized samples were characterized by XRD, SEM, TEM, FTIR, NH3-TPD, XRF and N2-physisorption techni...
Article
The kinetics of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst was studied by temperature-programmed reaction. Catalytic runs were performed in a fixed-bed quartz micro-reactor both under constant (620 °C) and rising temperature. The reaction temperature was increased from 600 to 650 °C in such a way that the propane co...
Article
The selective hydrogenation of acetylene to ethylene in acetylene/ethylene mixture over Pd-Ag/α-Al2O3 catalysts prepared by sequential impregnation method was studied. The α-Al2O3 support was prepared by thermal treatment of γ-Al2O3 in temperature range of 1,090–1,100 °C. The samples were characterized for their structural properties and coke depos...
Article
Full-text available
The influence of calcination temperature (500, 600 and 700 °C) on NiO–MgO solid solution formation and the performance of the resulting catalysts in CO2 reforming of methane was studied. The solid solutions and resulting catalysts were characterized by Brunauer–Emmett–Teller, XRD, temperature-programmed reduction (TPR), TEM and thermal gravimetric...
Article
Full-text available
Ru/Al2O3 catalysts were prepared by conventional incipient wetness impregnation as well as colloid deposition of RuCl3 precursor via in situ reduction with ethylene glycol (polyol) method on alumina support. The samples were characterized by TEM, XRD and TPR techniques. The catalytic performance tests were carried out in a fixed-bed micro-reactor u...
Article
The selective hydrogenation of acetylene to ethylene over Pd-Ag/α-Al2O3 catalysts prepared by different impregnation/reduction methods was studied. The best catalytic performance was achieved with the sample prepared by sequential impregnation. A kinetic model based on 1st order in acetylene and 0.5th order in hydrogen for the main reaction and 2nd...
Article
In a new approach, a series of NiO–MgO solid solution catalysts with different NiO contents (5, 10, 15 and 20 wt %) were prepared by one-pot sol–gel/evaporation method. Nitrogen adsorption/desorption, XRD, TPR, TGA, SEM and TEM techniques were used to correlate the activity and stability to the structural properties of the catalysts. The catalysts...
Article
Two types of copper-based dehydrogenation nanocatalysts (Cu/ZnO/Al2O3 and Cu/SiO2) were prepared from various precursors by impregnation (IM), sol-gel (SG) and co precipitation (COPRE) methods. The structures of samples were characterized by N2 adsorption-desorption, XRD, XRF, TPR, N2O-Titration, FT-IR, FE-SEM and TEM techniques. The catalytic perf...
Article
The effect of competitive adsorbate concentration and combination on the adsorption of H2PtCl6 onto γ-Al2O3 in the preparation and performance of PtSnK/γ-Al2O3 catalyst for propane dehydrogenation was investigated. The catalysts were prepared by sequential impregnation of Sn and Pt precursors. The effect of competitor concentration on Pt adsorption...
Article
Thermodynamic equilibrium analysis of carbon dioxide hydrogenation to methane and side reactions was performed using constrained Gibbs free energy minimization. The applicability for upgrading of CO2-rich natural gas in particular was investigated as a case study. The thermodynamics simulation to obtain equilibrium CO2 conversions and product compo...
Article
The catalytic performance of H-ZSM-5 samples prepared from different silica sources, namely, Ludox (sample A), waterglass (sample B) and tetraethyl orthosilicate (sample C) in aromatization of propane was studied. The catalysts were characterized by BET, SEM, XRD and NH3-TPD techniques to analyze the structure and acidity of the active sites. The p...
Article
A mathematical model for the impregnation step in the preparation of supported catalysts is developed. The kinetic parameters required for the model solution were obtained by considering the reversible competitive adsorption of ions on the same surface sites. The effects of pH of the impregnation solution and impregnation time, as two critical oper...
Article
The copper-silica (Cu/SiO2) nanosized catalysts were synthesized using various precursors by impregnation (IM) of amorphous silica, or sol–gel (SG) and co-precipitation (PRE) methods using sodium silicate or tetraethyl orthosilicate. The structures of catalysts were characterized by N2 adsorption-desorption, XRD, XRF, TPR, N2O-titration, FT-IR, FE-...
Article
A thermodynamic analysis of propane dehydrogenation with carbon dioxide was performed using constrained Gibbs free energy minimization method. Different reaction networks corresponding to different catalytic systems, including non-redox and redox oxide catalysts, were simulated. The influences of CO2/C3H8 molar ratio (1-10), temperature (700-1000 K...
Article
Thermodynamic equilibrium analysis of reforming of methane with carbon dioxide (dry reforming) and in combination with steam reforming (mixed reforming) was performed using constrained Gibbs free energy minimization method. The results were compared with that of a commercial plant reactor and our experimental data over Ni/MgO catalysts tested in a...
Article
A series of Ru/activated carbon (AC) catalysts promoted with potassium and barium were prepared by impregnation method for ammonia synthesis. The chemical treatments effects of the support on catalytic performance were studied by modifying AC with H2 (ACH) and H2 + nitric acid (ACHN). The catalysts were characterized by using nitrogen adsorption/de...
Article
The effect of boron incorporation into H-ZSM-5 nanocatalyst on the stability, product distribution and hydrocarbons selectivity in methanol to olefins (MTO) reaction was investigated. The reference and boron-modified ZSM-5 nanocatalysts were prepared by hydrothermal method. The fresh and used nanocatalysts were characterized using TG-DTA, XRD, FE-S...
Article
High-silica H-ZSM-5 catalysts (Si/Al = 200) were successfully synthesized using the conventional hydrothermal method under a static condition in the presence of tetrapropyl ammonium hydroxide (TPAOH), tetrapropyl ammonium bromide (TPABr), n-butyl amine (NBA) and morpholine (MOR) as the structure-directing agents. The influence of the templates on t...
Article
Modified γ-Al2O3 nanocatalyst containing 2 wt.% SiO2 prepared by precipitation method showed high and stable performance in methanol dehydration to DME. Fractional factorial design (FFD) was used for optimization of preparation conditions. The pH of precipitation and the precipitating agent were found to have high influence on the methanol conversi...
Article
Despite technological developments within the past century, ammonia synthesis from nitrogen and hydrogen is still highly energy intensive due to high-pressure operation. Even with recently introduced Ru-based catalysts with superior performance over conventional iron-based catalysts, there is still room for improvements to approach the theoretical...
Article
Binary Cu/ZnO methanol synthesis catalysts were prepared by the co-precipitation of copper and zinc hydroxycarbonates using different initial solution concentrations, stirring rates and aging times and temperatures during precipitation, and different calcination temperatures of the precipitated hydroxycarbonates. The precipitates (catalyst precurso...
Article
Chemical equilibria of propane aromatization under both unrestricted coke-formation and coke-free operating conditions were studied. In both cases, propane conversions were nearly complete. The aromatics selectivity was observed to be 46% at a temperature of 823 K (1 bar) under coke-free operating conditions. Application of hydrogen and steam as co...
Article
Full-text available
The reduction of greenhouse gas emissions is an ever-increasing challenge for production units and power plants in view of the global warming concerns. Carbon dioxide capturing from petrochemical process streams and flares has been recognized as one of the several strategies necessary for mitigating the emission of greenhouse gases into the atmosph...
Article
Full-text available
The H-ZSM-5(SiO2/Al2O3=35) catalyst was synthesized hydrothermally using commercial waterglass as the silica source and it was characterized by XRD, BET, SEM and NH3-TPD techniques. Isobutane aromatization over the prepared catalyst was studied and the results were compared with those of propane in a fixed-bed reactor. Despite higher conversion of...
Article
The effect of propane addition to the feed of methane aromatization process was studied both thermodynamically and experimentally. Thermodynamic equilibrium calculations were performed within temperature, pressure, and CH4/C3H8 molar ratio ranges of 673–873 K, 1–10 bar, and 0–20, respectively, considering different constraints according to two alte...
Article
As one of the major contaminates in natural gas feeds, CO2 must optimally be removed as it reduces the energy content of the gas and affect its selling price. The presence of CO2 in natural gas remains one of the challenging gas separation problems in process engineering for CO2/CH4 systems. An overview of gas processing technologies for CO2 remova...
Article
The kinetics of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst were studied. Performance test runs were carried out in a fixed-bed integral reactor. Using a power-law rate expression for the surface reaction kinetics and independent law for deactivation kinetics, the experimental data were analyzed both by integral and...
Article
The applicability of a commercial Pt-Sn/Al2O3 isobutane dehydrogenation catalyst in dehydrogenation of propane was studied. Catalyst performance tests were carried out in a fixed-bed quartz reactor under different operating conditions. Generally, as the factors improving propane conversion decrease the propylene selectivity, the optimal operating c...
Article
Full-text available
The effect of oxygenate additives, water and methanol, to the feed on the performance of industrial Pt–Sn/γ-Al2O3 catalyst in dehydrogenation of propane was studied by neural network modeling. Because of the complex nature of the system and very low levels of oxygenate addition, neural networks were employed as an efficient and accurate tool to obt...
Article
The effect of the solvent used for the preparation of Pt–Sn/θ-Al2O3 catalysts via impregnation method on the properties of the catalyst was studied. The catalysts were prepared by co-impregnation of alumina support with the acidic solutions of H2PtCl6 and SnCl2 using water, ethanol and acetone as the solvents. The performance tests for propane dehy...
Article
The conversion of natural gas (methane) as an alternative to petroleum into valuable chemicals and clean fuels has received much attention. However, because of high stability and symmetry of methane molecule, relatively few number of natural gas conversions, mostly indirect routes, have been commercialized and the remainders are still not competiti...
Article
The thermodynamics of methane dehydroaromatization in the absence and presence of coke-removing agents was studied using the Gibbs free energy minimization approach. Numerical results indicated that higher temperatures and lower pressures increase methane conversion as well as formation of olefins and aromatics but suppress that of paraffins. Highe...
Article
The kinetics of reactions involved in dehydrogenation of propane to propylene over Pt–Sn/Al2O3 catalyst was studied. The simultaneous deactivation of individual dehydrogenation, hydrogenolysis and cracking sites was also studied. A model was developed to obtain the transient conversion of propane, product selectivity and catalytic site activity. Th...
Article
The oxidative coupling of methane over La2O3/CaO type-catalyst in a fixed-bed reactor is studied under a wide range of operating conditions (973<T< 1103 K, 55< ptotal <220 kPa, and 3.7< mcat/VSTP <50 kg·s/m3). A ten-step kinetic model incorporating all main products was used to predict the behavior of the system. Methane conversions and C2 selectiv...
Article
We report the propane dehydrogenation behavior of catalysts prepared using wet impregnation method that immobilize Pt nano cluster on the alumina surface. The immobilization of the metal particles and their nano size dimensions were demonstrated by transmission electron microscopy. Selectivity to propylene for these catalysts is comparable to those...
Article
The effect of oxygenate modifiers on the performance of Pt–Sn/γ–Al2O3 catalyst in dehydrogenation of propane was studied. Dehydrogenation reaction was carried out in a fixed-bed quartz reactor in the temperature range of 575–620 °C. Two types of oxygenate modifiers, namely water and methanol, were added to the feed. The optimum amounts of water for...
Article
The mitigation of greenhouse gas emissions to acceptable levels is arguably the greatest environmental challenge these days. Vast utilization of fossil fuels and forest destruction are main causes of CO2 increase in the atmosphere. Carbon dioxide sequestration that consists of separation, transportation and utilization or storage of CO2, is one way...
Article
The increase of atmospheric carbon dioxide and the global warming due to its greenhouse effect resulted in worldwide concerns. On the other hand, carbon dioxide might be considered as a valuable and renewable carbon source. One approach to reduce carbon dioxide emissions could be its capture and recycle via transformation into chemicals using the t...
Article
The dehydrogenation of isobutane to isobutene in adiabatic radial-flow moving-bed reactors was studied. First order rate expressions were considered for the primary reaction and deactivation kinetics incorporating the reversibility of dehydrogenation reaction. Kinetic data from a fixed-bed lab-scale reactor were used for modeling of the commercial...
Conference Paper
Coke formation rates under propane dehydrogenation reaction conditions on a used Pt-Sn-K/Al2O3 catalyst have been experimentally determined in a thermo-gravimetric analysis (TG/DTA) as a function of time on stream covering wide temperature and concentration ranges. Here we demonstrated how different active phase distribution profiles can affect the...
Conference Paper
Different thin-step type of Three-metallic (Pt-Sn-K) catalysts based on Pt and supported on different materials (-Al2O3 , θ-Al2O3)were tested in the propane dehydrogenation reaction (in fixed-bed reactor). Results show that the non-uniform catalysts on θ-Al2O3 has a better performance in propane dehydrogenation (high yield to propylene and low co...
Article
The extent of side reactions in propane dehydrogenation over Pt-Sn/Al 2 O 3 catalyst was studied. Catalytic test runs were carried out in a fixed-bed quartz reactor under different operating conditions. The results showed that the extent of side reactions strongly depends on the operating conditions. The product distribution implied that single C-C...
Conference Paper
The adsorption of hexachloroplatinic acid and tin chloride on γ-Al2O3 was studied. Pt-Sn/γ-Al2O3 catalyst samples were prepared by sequential impregnation of hexachloroplatinic acid and tin chloride on the support. The amount of solute adsorption was determined through the difference of the initial and final concentration of the solute. Among diffe...
Article
The deactivation of promoted Pt-Al2O3 catalyst in dehydrogenation of C10–C14 normal paraffins to the corresponding mono-olefins was studied. Two models based on reversible and irreversible main reaction and nth order, concentration-independent deactivation kinetic was used. The kinetic parameters were obtained by utilizing non-linear estimation fun...
Article
Several SAPO-34 samples with different Si/Al ratio (0.05–0.5) of synthesis gel were prepared hydrothermally at crystallization temperature of 190–215°C. The products were characterized by XRD, SEM/EDX, NH3-TPD, FT-IR and nitrogen adsorption techniques. EDX data showed a deviation of elemental composition of products with respect to the Al, Si, and...
Article
A mathematical model for the performance of a radial-flow moving-bed reactor for dehydrogena- tion of light paraffins was developed. Assuming relevant kinetic expressions for the main reaction and catalyst deactivation, the kinetic parameters were obtained through lab-scale fixed-bed reactor testing using the integral method of analysis. The conver...
Article
In this paper, the effects of K 2O promoter on the activity, stability, and coke deposition of nickel catalysts supported on mesoporous nanocrystalline zirconia powder with high surface area and pure tetragonal crystallite phase were investigated in methane reforming with carbon dioxide. The samples were characterized by X-ray diffraction (XRD), BE...
Article
A series of commercially available γ-Al2O3 samples were tested for vapor-phase dehydration of methanol to dimethyl ether (DME). The samples were characterized using X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3−TPD), and Brunauer−Emmett−Teller (BET) surface area techniques. The catalysts were determined to be highly amo...
Article
Mesoporous nanocrystalline zirconia with high surface area and pure tetragonal crystallite phase has been prepared by bifunctional ethylene diamine as both precipitating agent for ZrO(NO3)2 to ZrO(OH)2 and colloidal protecting agent for the ZrO(OH)2 nanoparticles. The effect of refluxing time and temperature on the structural properties of the zirc...
Article
The liquid-phase dehydration of 1,4-butanediol to tetrahydrofuran was investigated over various materials including synthetic zeolites, namely, ZSM-5, Y, Mordenite, Ferrierite, and Beta as well as silica and alumina. The key characters investigated were the Si/Al ratio and cation exchange. The results showed that the ZSM-5 zeolite exchanged with NH...
Conference Paper
Full-text available
In the absence of powerful rigorous models, in this research a simple but practical method for calculating the temperature and residence time and carbon black yield in oil-furnace reactors is proposed. For this purpose an empirical formula of the form Cx Hy is assumed for the carbon black feedstock based on typical feedstock used in this industry....
Article
In the present work, Tetrahydrofuran was produced from 1,4-butanediol by catalytically dehydration of 1,4-butanediol in contact with a catalyst. Material used as catalyst were Synthesized and natural zeolites as well as alumina and silica. Synthesized zeolites were investigated in different aspect such as pore size, cation and Si/Al ratio. Results...
Article
Dimensional analysis of the governing equations in liquid-phase, solid-acid-catalyzed alkylation was used to develop an empirical model for the catalyst lifetime in terms of important operating variables. It was found that the dimensionless catalyst lifetime in a continuous stirred tank reactor was a function of four dimensionless groups, incorpora...
Article
The differential form of the decay law for a solid acid catalyst in liquid-phase alkylation of isobutane with butenes was investigated. A pseudo-first order expression for the intrinsic rate of the main reaction and a pseudo-second order one for the poisoning reaction were assumed. The role of intraparticle diffusion on the apparent deactivation be...
Article
The deactivation of solid acid catalysts in liquid-phase alkylation of isobutane with butenes was investigated. The role of pore mouth plugging, in particular, was studied and it was found that it had a significant effect on the deactivation behavior. Simple explicit correlations were developed for catalyst lifetime in a CSTR, both in terms of time...