Journal of Industrial and Engineering Chemistry, 2010
An active cobalt-manganese catalyst was prepared by co-precipitation method, and was also tested ... more An active cobalt-manganese catalyst was prepared by co-precipitation method, and was also tested for hydrogenation of carbon monoxide to light olefins. The catalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area techniques. The kinetic experiments on a well-characterized Co-Mn/TiO 2 catalyst were performed in a fixed-bed micro-reactor, and were also conducted in a temperature range of 190-280 8C, pressure range of 1-10 bar, H 2 /CO feed ratio (mol/mol) range of 1-3 and a space velocity range of 2700-5200 h À1 . Two kinetic expressions based on Langmuir-Hinshelwood-Houngen-Watson (LHHW) mechanism were observed to fit the experimental data accurately for Fischer-Tropsch synthesis reaction. The kinetic parameters were estimated with non-linear regression method. Activation energies obtained were 35.131 and 44.613 kJ/mol for optimal kinetics models. ß
Cobalt-manganese catalyst is widely studied in Fischer-Tropsch synthesis to obtain light olefins ... more Cobalt-manganese catalyst is widely studied in Fischer-Tropsch synthesis to obtain light olefins from synthesis gas. However, selectivity and mechanical strength of the catalyst differ depending on its preparation method and type of reactor. The main objective of this paper is to develop a better understanding of manufacturing parameters affecting attrition strength and selectivity of the catalyst. The cobalt-manganese oxide nano-catalysts were prepared using co-precipitation method. The fine powders were then formed using tabletting-crushing (pelletizing) process to obtain the catalyst pellets. The original unformed and formed catalysts were explored for the conversion of synthesis gas to the light olefins in a standard laboratory fixed bed reactor considering selectivity to ethylene and propylene. The processing variables investigated were included of type and concentration of binder and compression pressure in pelletizing process. Furthermore, the attrition assessment of catalyst was carried out using a rotary bottle shake system. The results presented in this work revealed that forming the catalyst under 75 bar compression pressure and 4 wt.% Syton binder led to the maximum selectivity. In the attrition evaluation, it was found that the extent of attrition was the least at the same forming conditions (75 bar, 4 wt.% Syton).
Bioleaching of copper from the flue dust of the Sarcheshmeh copper smelter has been investigated.... more Bioleaching of copper from the flue dust of the Sarcheshmeh copper smelter has been investigated. A series of continuous tests were carried out in two-stages of airlift bioreactors inoculated with the acidophilic, iron and sulfur oxidizing bacteria, initially derived from acid mine drainage. The effects of different parameters such as pulp density, retention time and temperature on the mesophile bioleach
A series of solid-acid catalysts comprised of γ-alumina and modified γ-alumina with different of ... more A series of solid-acid catalysts comprised of γ-alumina and modified γ-alumina with different of silica were prepared by co-precipitation method. The catalysts were characterized using XRD, TGA, NH 3 -TPD and BET techniques. Dehydration of methanol to dimethyl ether (DME) on solid-acid catalysts was studied in a fixed-bed reactor at the same operating conditions (T = 300°C, P = 16 bar, WHSV = 26.07 h − 1 ). According to the experimental results, silica-modified catalysts have shown better performance compared to the pure γ-alumina. It was found that surface areas increase with increasing silica loading. The results of NH 3 -TPD analysis showed that the surface acidity of aluminosilicate catalysts increases with increase in SiO 2 /Al 2 O 3 molar ratio. Also, it was found that the catalysts with highest portion of weak and/or moderate acid sites exhibit the best catalytic performance and stability. The sample with 3 wt.% silica loading has exhibited the best activity for methanol conversion.
A series of micro-mesoporous ZSM-5/MCM-41 composite molecular sieves were prepared by combining a... more A series of micro-mesoporous ZSM-5/MCM-41 composite molecular sieves were prepared by combining a microporous zeolite silica source with nano self-assembly methods, and characterized by SEM, TEM, XRD, N 2 adsorption and desorption, TPD of ammonia, and their catalytic performance for the dehydration of methanol to dimethyl ether (DME) in a fixed bed microreactor at atmospheric pressure. Among these catalysts, the ZSM-5/MCM-41 sample alkali-treated with 1.5 mol/L NaOH solution, in which the relative crystallinity of ZSM-5 and MCM-41 are 54.5% and 30.5%, respectively, gave the best activity (X MeOH > 80%) with 100% selectivity and a long lifetime in a wide range of temperature from 190 • C to 300 • C. From the characterization and activity data, the formation mechanism of the micro-mesoporous composite molecular sieves was proposed to be a liquid-crystal templating mechanism.
Journal of Industrial and Engineering Chemistry, 2010
An active cobalt-manganese catalyst was prepared by co-precipitation method, and was also tested ... more An active cobalt-manganese catalyst was prepared by co-precipitation method, and was also tested for hydrogenation of carbon monoxide to light olefins. The catalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area techniques. The kinetic experiments on a well-characterized Co-Mn/TiO 2 catalyst were performed in a fixed-bed micro-reactor, and were also conducted in a temperature range of 190-280 8C, pressure range of 1-10 bar, H 2 /CO feed ratio (mol/mol) range of 1-3 and a space velocity range of 2700-5200 h À1 . Two kinetic expressions based on Langmuir-Hinshelwood-Houngen-Watson (LHHW) mechanism were observed to fit the experimental data accurately for Fischer-Tropsch synthesis reaction. The kinetic parameters were estimated with non-linear regression method. Activation energies obtained were 35.131 and 44.613 kJ/mol for optimal kinetics models. ß
Cobalt-manganese catalyst is widely studied in Fischer-Tropsch synthesis to obtain light olefins ... more Cobalt-manganese catalyst is widely studied in Fischer-Tropsch synthesis to obtain light olefins from synthesis gas. However, selectivity and mechanical strength of the catalyst differ depending on its preparation method and type of reactor. The main objective of this paper is to develop a better understanding of manufacturing parameters affecting attrition strength and selectivity of the catalyst. The cobalt-manganese oxide nano-catalysts were prepared using co-precipitation method. The fine powders were then formed using tabletting-crushing (pelletizing) process to obtain the catalyst pellets. The original unformed and formed catalysts were explored for the conversion of synthesis gas to the light olefins in a standard laboratory fixed bed reactor considering selectivity to ethylene and propylene. The processing variables investigated were included of type and concentration of binder and compression pressure in pelletizing process. Furthermore, the attrition assessment of catalyst was carried out using a rotary bottle shake system. The results presented in this work revealed that forming the catalyst under 75 bar compression pressure and 4 wt.% Syton binder led to the maximum selectivity. In the attrition evaluation, it was found that the extent of attrition was the least at the same forming conditions (75 bar, 4 wt.% Syton).
Bioleaching of copper from the flue dust of the Sarcheshmeh copper smelter has been investigated.... more Bioleaching of copper from the flue dust of the Sarcheshmeh copper smelter has been investigated. A series of continuous tests were carried out in two-stages of airlift bioreactors inoculated with the acidophilic, iron and sulfur oxidizing bacteria, initially derived from acid mine drainage. The effects of different parameters such as pulp density, retention time and temperature on the mesophile bioleach
A series of solid-acid catalysts comprised of γ-alumina and modified γ-alumina with different of ... more A series of solid-acid catalysts comprised of γ-alumina and modified γ-alumina with different of silica were prepared by co-precipitation method. The catalysts were characterized using XRD, TGA, NH 3 -TPD and BET techniques. Dehydration of methanol to dimethyl ether (DME) on solid-acid catalysts was studied in a fixed-bed reactor at the same operating conditions (T = 300°C, P = 16 bar, WHSV = 26.07 h − 1 ). According to the experimental results, silica-modified catalysts have shown better performance compared to the pure γ-alumina. It was found that surface areas increase with increasing silica loading. The results of NH 3 -TPD analysis showed that the surface acidity of aluminosilicate catalysts increases with increase in SiO 2 /Al 2 O 3 molar ratio. Also, it was found that the catalysts with highest portion of weak and/or moderate acid sites exhibit the best catalytic performance and stability. The sample with 3 wt.% silica loading has exhibited the best activity for methanol conversion.
A series of micro-mesoporous ZSM-5/MCM-41 composite molecular sieves were prepared by combining a... more A series of micro-mesoporous ZSM-5/MCM-41 composite molecular sieves were prepared by combining a microporous zeolite silica source with nano self-assembly methods, and characterized by SEM, TEM, XRD, N 2 adsorption and desorption, TPD of ammonia, and their catalytic performance for the dehydration of methanol to dimethyl ether (DME) in a fixed bed microreactor at atmospheric pressure. Among these catalysts, the ZSM-5/MCM-41 sample alkali-treated with 1.5 mol/L NaOH solution, in which the relative crystallinity of ZSM-5 and MCM-41 are 54.5% and 30.5%, respectively, gave the best activity (X MeOH > 80%) with 100% selectivity and a long lifetime in a wide range of temperature from 190 • C to 300 • C. From the characterization and activity data, the formation mechanism of the micro-mesoporous composite molecular sieves was proposed to be a liquid-crystal templating mechanism.
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