A series of Co (10.7 wt. %)-CeO2/SiO2 catalysts with various cerium contents was prepared and evaluated. The optimized ceria-promoted catalyst exhibits good activity, high selectivity towards long chain hydrocarbons, ...A series of Co (10.7 wt. %)-CeO2/SiO2 catalysts with various cerium contents was prepared and evaluated. The optimized ceria-promoted catalyst exhibits good activity, high selectivity towards long chain hydrocarbons, and excellent stability. The promotion mechanism of ceria was investigated using X-ray diffraction (XRD), temperature programmed reduction (TPR), H2 temperature programmed surface reaction (H2-TPSR) and transient response technique. It is suggested that the improved catalytic performance of the catalyst modified by ceria be attributed to (1) the improvement in the dispersion of metallic cobalt and the amount of active sites for Fischer-Tropsch Synthesis (FTS), leading to an increased concentration of surface active carbon species and high selectivity towards long chain hydrocarbons; (2) the inhibition of disproportionation of CO and the removal of inactive surface carbon species.展开更多
The purpose of this study was to investigate the effect of preadsorbed CO at different temperatures, calcination temperatures, the combined influence of reduction temperature and time, and pretreatment using hydrogen ...The purpose of this study was to investigate the effect of preadsorbed CO at different temperatures, calcination temperatures, the combined influence of reduction temperature and time, and pretreatment using hydrogen or syngas as reduction agents on the F-T synthesis （FTS） activity and selectivity of Co/Al2O3 catalyst. The reactivity of the carbon species at higher preadsorption temperature with H2 in TPSR decreased, whereas the carbon-containing species showed higher reactivity over Co/Al2O3 catalyst with low calcination temperature. This agreed well with the order of catalytic activity for F-T synthesis on this catalyst. The catalytic activity of the catalyst varied with reduction temperature and time remarkably. CODEX optimization gave an optimum reduction temperature of 756 K and reduction time of 6.2 h and estimated C5＋ yield perfectly. The pretreatment of Co/Al2O3 catalyst with different reduction agents （hydrogen or syngas） showed important influences on the catalytic performance. A high CO conversion and C5＋ yield were obtained on the catalyst reduced by hydrogen, whereas methane selectivity on the catalyst reduced by syngas was much higher than that on the catalyst reduced by hydrogen.展开更多
文摘A series of Co (10.7 wt. %)-CeO2/SiO2 catalysts with various cerium contents was prepared and evaluated. The optimized ceria-promoted catalyst exhibits good activity, high selectivity towards long chain hydrocarbons, and excellent stability. The promotion mechanism of ceria was investigated using X-ray diffraction (XRD), temperature programmed reduction (TPR), H2 temperature programmed surface reaction (H2-TPSR) and transient response technique. It is suggested that the improved catalytic performance of the catalyst modified by ceria be attributed to (1) the improvement in the dispersion of metallic cobalt and the amount of active sites for Fischer-Tropsch Synthesis (FTS), leading to an increased concentration of surface active carbon species and high selectivity towards long chain hydrocarbons; (2) the inhibition of disproportionation of CO and the removal of inactive surface carbon species.
基金The National Basic Research Program of China (973 Program) (No. 2005CB221402)China National Petroleum Corporation
文摘The purpose of this study was to investigate the effect of preadsorbed CO at different temperatures, calcination temperatures, the combined influence of reduction temperature and time, and pretreatment using hydrogen or syngas as reduction agents on the F-T synthesis （FTS） activity and selectivity of Co/Al2O3 catalyst. The reactivity of the carbon species at higher preadsorption temperature with H2 in TPSR decreased, whereas the carbon-containing species showed higher reactivity over Co/Al2O3 catalyst with low calcination temperature. This agreed well with the order of catalytic activity for F-T synthesis on this catalyst. The catalytic activity of the catalyst varied with reduction temperature and time remarkably. CODEX optimization gave an optimum reduction temperature of 756 K and reduction time of 6.2 h and estimated C5＋ yield perfectly. The pretreatment of Co/Al2O3 catalyst with different reduction agents （hydrogen or syngas） showed important influences on the catalytic performance. A high CO conversion and C5＋ yield were obtained on the catalyst reduced by hydrogen, whereas methane selectivity on the catalyst reduced by syngas was much higher than that on the catalyst reduced by hydrogen.
