A physical mixture of alkali-promoted iron catalyst with binder based on Fischer-Tropsch synthesis and an acidic co-catalyst （HZSM5） for syngas conversion to hydrocarbons was studied in a fixed bed micro reactor. De...A physical mixture of alkali-promoted iron catalyst with binder based on Fischer-Tropsch synthesis and an acidic co-catalyst （HZSM5） for syngas conversion to hydrocarbons was studied in a fixed bed micro reactor. Deactivation data were obtained during the synthesis over a 1400 h period. The deactivation studies on iron catalyst showed that this trend followed the phase transformation Fe2.2C （ ε′） → Fe5C2 （χ） → Fe3C （θ）, and the final predominant phase of the catalyst was Fe3C （θ）. Deactivation of zeolite component in bifunctional catalyst may be caused by coking over the zeolitic component, dealumination of zeolite crystals, and migration of alkali promoters from iron catalyst under synthesis conditions. The deactivation rate of iron catalyst was also obtained.展开更多
The detailed kinetics of Fischer-Tropsch synthesis over an industrial Fe/Cu/La/Si catalyst was studied in a continuous spinning basket re- actor under the conditions relevant to industrial operations. Reaction rate eq...The detailed kinetics of Fischer-Tropsch synthesis over an industrial Fe/Cu/La/Si catalyst was studied in a continuous spinning basket re- actor under the conditions relevant to industrial operations. Reaction rate equations were derived on the basis of Langmuir-Hinshelwood- Hougen-Watson type models for Fischer-Tropsch synthesis based on possible reactions sets originated from the carbide, enolic and combined enol/carbide mechanisms. Kinetic model candidates were evaluated by the global optimization of kinetic parameters, which were realized by first minimization of multi-response objective functions with conventional Levenberg-Marquardt method. It was found that an enolic mech- anism based model could produce a good fit of the experimental data. The activation energy for paraffin formation is 95 kJ.mo1-1 which is smaller than that for olefin formation （121 kJ.mol-1）.展开更多
The effect of reduction procedure on catalyst properties, activity and products selectivity of ruthenium-promoted Co/γ-Al2O3 catalyst in Fischer-Tropsch synthesis （FTS） was investigated. Catalyst samples were redu...The effect of reduction procedure on catalyst properties, activity and products selectivity of ruthenium-promoted Co/γ-Al2O3 catalyst in Fischer-Tropsch synthesis （FTS） was investigated. Catalyst samples were reduced with different reduction gas compositions and passivated before being characterized by TPR and XRD techniques. Different activity and product selectivity analyses were also performed. These results showed that the catalyst dispersion, particle size, and the degree of reduction changed with different reduction gas compositions, which were resulted from the water partial pressures in reduction process that give varying degrees of interaction with the support. It has been suggested that the FTS activity of cobalt catalyst was directly dependent on the catalyst reducibility. A reduction gas with a molar ratio of H2Prle = 1 was used to prevent the formation of Co-support compound during catalyst reduction.展开更多
Reaction modeling of SMR (Steam Methane Reforming) process inside monolith reactors using two approaches were investigated and compared with each other. In the first approach, the reactions were assumed to take place ...Reaction modeling of SMR (Steam Methane Reforming) process inside monolith reactors using two approaches were investigated and compared with each other. In the first approach, the reactions were assumed to take place exactly on the wall surfaces, while in the second approach they considered inside a thin thickness near the walls. Experiments of SMR were carried out in a lab-scale monolith reactor. A single-channel was considered and CFD model were developed for each of aforementioned approaches. Comparisons between modeling results and experimental data showed that the first approach (surface model) gives better results. Performing reactions are difficult and expensive, CFD simulations are considered as numerical experiments in many cases. It was concluded that obtained results from CFD analysis gives precise guidelines for further studies on optimization of SMR monolithic reactor performance.展开更多
文摘A physical mixture of alkali-promoted iron catalyst with binder based on Fischer-Tropsch synthesis and an acidic co-catalyst （HZSM5） for syngas conversion to hydrocarbons was studied in a fixed bed micro reactor. Deactivation data were obtained during the synthesis over a 1400 h period. The deactivation studies on iron catalyst showed that this trend followed the phase transformation Fe2.2C （ ε′） → Fe5C2 （χ） → Fe3C （θ）, and the final predominant phase of the catalyst was Fe3C （θ）. Deactivation of zeolite component in bifunctional catalyst may be caused by coking over the zeolitic component, dealumination of zeolite crystals, and migration of alkali promoters from iron catalyst under synthesis conditions. The deactivation rate of iron catalyst was also obtained.
文摘The detailed kinetics of Fischer-Tropsch synthesis over an industrial Fe/Cu/La/Si catalyst was studied in a continuous spinning basket re- actor under the conditions relevant to industrial operations. Reaction rate equations were derived on the basis of Langmuir-Hinshelwood- Hougen-Watson type models for Fischer-Tropsch synthesis based on possible reactions sets originated from the carbide, enolic and combined enol/carbide mechanisms. Kinetic model candidates were evaluated by the global optimization of kinetic parameters, which were realized by first minimization of multi-response objective functions with conventional Levenberg-Marquardt method. It was found that an enolic mech- anism based model could produce a good fit of the experimental data. The activation energy for paraffin formation is 95 kJ.mo1-1 which is smaller than that for olefin formation （121 kJ.mol-1）.
文摘The effect of reduction procedure on catalyst properties, activity and products selectivity of ruthenium-promoted Co/γ-Al2O3 catalyst in Fischer-Tropsch synthesis （FTS） was investigated. Catalyst samples were reduced with different reduction gas compositions and passivated before being characterized by TPR and XRD techniques. Different activity and product selectivity analyses were also performed. These results showed that the catalyst dispersion, particle size, and the degree of reduction changed with different reduction gas compositions, which were resulted from the water partial pressures in reduction process that give varying degrees of interaction with the support. It has been suggested that the FTS activity of cobalt catalyst was directly dependent on the catalyst reducibility. A reduction gas with a molar ratio of H2Prle = 1 was used to prevent the formation of Co-support compound during catalyst reduction.
文摘Reaction modeling of SMR (Steam Methane Reforming) process inside monolith reactors using two approaches were investigated and compared with each other. In the first approach, the reactions were assumed to take place exactly on the wall surfaces, while in the second approach they considered inside a thin thickness near the walls. Experiments of SMR were carried out in a lab-scale monolith reactor. A single-channel was considered and CFD model were developed for each of aforementioned approaches. Comparisons between modeling results and experimental data showed that the first approach (surface model) gives better results. Performing reactions are difficult and expensive, CFD simulations are considered as numerical experiments in many cases. It was concluded that obtained results from CFD analysis gives precise guidelines for further studies on optimization of SMR monolithic reactor performance.
