On the basis of the global CO consumption rate model, the lumped product distribution model and the sedimenta- tion-dispersion model of a catalyst, a steady-state, one-dimensional mathematical model of the slurry bubb...On the basis of the global CO consumption rate model, the lumped product distribution model and the sedimenta- tion-dispersion model of a catalyst, a steady-state, one-dimensional mathematical model of the slurry bubble column reactor for Fischer-Tropsch synthesis were established. The mathematical simulation of the slurry bubble column reactor for Fischer-Tropsch synthesis was carried out under the following typical industrial operating conditions： temperature 230 ℃, pressure 3.0 MPa, gas flow 5x 105 m3/h, catalyst content in slurry phase 30%, reactor diameter 5.0 m and the composition of feed gas： y（H2）=0.60, y（CO）=0.30, y（N2）=0.10. The influences of operating pressure, temperature and re（HE）Ira（CO） in feed gas on the reactor＇s reaction performance were simulated.展开更多
The promotional effects of Zr on the structure, reduction, carburization and catalytic behavior of precipitated iron-based Fischer-Tropsch synthesis （FTS） catalysts were investigated. The catalysts were characterize...The promotional effects of Zr on the structure, reduction, carburization and catalytic behavior of precipitated iron-based Fischer-Tropsch synthesis （FTS） catalysts were investigated. The catalysts were characterized by N2 physisorption, temperature-programmed reduction （TPR）, and M6ssbauer effect spectroscopy （MES） techniques. As revealed by N2 physisorption, Zr decreased the BET surface area and pore volume of the catalyst. The results of TPR and MES show that Zr suppresses the reduction and carburization of Fe catalysts because of the interaction between Fe and Zr. The FTS reaction results indicate that Zr decreases the FTS activity of Fe catalysts but improves the catalysts＇ stability. In addition, Zr promoter restraines the formation of light hydrocarbons （methane and C2-C4） and shifts the production distribution to the heavy hydrocarbons.展开更多
The diffusion and reaction phenomenon in a Fe-based catalyst pellet for Fischer-Tropsch synthesis was studied. It was considered that the pores of catalyst pellets were full of liquid wax under Fischer-Tropsch synthes...The diffusion and reaction phenomenon in a Fe-based catalyst pellet for Fischer-Tropsch synthesis was studied. It was considered that the pores of catalyst pellets were full of liquid wax under Fischer-Tropsch synthesis conditions. The re- actants diffused from the bulk gas phase to the external surface of the pellet, and then the reactants diffused through the wax inside the pellet and reacted on the internal surface formed along the pore passages of the pellet. On the basis of reaction kinetics and double a-ASF product distribution model, a diffusion and reaction model of catalyst pellet was established. The effects of diffusion and reaction interaction in a catalyst pellet, the bulk temperature, the reaction pressure and the pellet size on the reactivity were further investigated. The relationship between the internal diffusion effectiveness factor of spherical catalyst pellet and the Thiele modulus were also discussed. The bulk temperature and pellet size have significant effects on the reactivity, while the pressure shows only a slight influence on the reactivity. The internal diffusion effectiveness factor decreases with an increasing Thiele modulus.展开更多
Silica nanotubes(SNT) have been synthesized using carbon nanotubes(CNT) as a template.Silica-coated carbon nanotubes(SNT-CNT) and SNT were loaded with a cobalt catalyst for use in Fischer-Tropsch synthesis(FTS).The ca...Silica nanotubes(SNT) have been synthesized using carbon nanotubes(CNT) as a template.Silica-coated carbon nanotubes(SNT-CNT) and SNT were loaded with a cobalt catalyst for use in Fischer-Tropsch synthesis(FTS).The catalysts were prepared by incipient wetness impregnation and characterized by N2 physisorption,X-ray diffraction(XRD),hydrogen temperature programmed reduction(H2-TPR) and transmission electron microscopy(TEM).FTS performance was evaluated in a fixed-bed reactor at 493 K and 1.0 MPa.Co/CNT and Co/SNT catalysts showed higher activity than Co/SNT-CNT in FTS because of the smaller cobalt particle size,higher dispersion and stronger reducibility.The results also showed that structure of the support affects the product selectivity in FTS.The synergistic effects of cobalt particle size,catalytic activity and diffusion limitations as a consequence of its small average pore size lead to medium selectivity to C5+ hydrocarbons and CH4 over Co/SNT-CNT.On the other hand,the Co/CNT showed higher CH4 selectivity and lower C5+ selectivity than Co/SNT,due to its smaller average pore size and cobalt particle size.展开更多
文摘On the basis of the global CO consumption rate model, the lumped product distribution model and the sedimenta- tion-dispersion model of a catalyst, a steady-state, one-dimensional mathematical model of the slurry bubble column reactor for Fischer-Tropsch synthesis were established. The mathematical simulation of the slurry bubble column reactor for Fischer-Tropsch synthesis was carried out under the following typical industrial operating conditions： temperature 230 ℃, pressure 3.0 MPa, gas flow 5x 105 m3/h, catalyst content in slurry phase 30%, reactor diameter 5.0 m and the composition of feed gas： y（H2）=0.60, y（CO）=0.30, y（N2）=0.10. The influences of operating pressure, temperature and re（HE）Ira（CO） in feed gas on the reactor＇s reaction performance were simulated.
文摘The promotional effects of Zr on the structure, reduction, carburization and catalytic behavior of precipitated iron-based Fischer-Tropsch synthesis （FTS） catalysts were investigated. The catalysts were characterized by N2 physisorption, temperature-programmed reduction （TPR）, and M6ssbauer effect spectroscopy （MES） techniques. As revealed by N2 physisorption, Zr decreased the BET surface area and pore volume of the catalyst. The results of TPR and MES show that Zr suppresses the reduction and carburization of Fe catalysts because of the interaction between Fe and Zr. The FTS reaction results indicate that Zr decreases the FTS activity of Fe catalysts but improves the catalysts＇ stability. In addition, Zr promoter restraines the formation of light hydrocarbons （methane and C2-C4） and shifts the production distribution to the heavy hydrocarbons.
基金Financial support from the National Basic Research Program of China(973 Program,2010CB736203)
文摘The diffusion and reaction phenomenon in a Fe-based catalyst pellet for Fischer-Tropsch synthesis was studied. It was considered that the pores of catalyst pellets were full of liquid wax under Fischer-Tropsch synthesis conditions. The re- actants diffused from the bulk gas phase to the external surface of the pellet, and then the reactants diffused through the wax inside the pellet and reacted on the internal surface formed along the pore passages of the pellet. On the basis of reaction kinetics and double a-ASF product distribution model, a diffusion and reaction model of catalyst pellet was established. The effects of diffusion and reaction interaction in a catalyst pellet, the bulk temperature, the reaction pressure and the pellet size on the reactivity were further investigated. The relationship between the internal diffusion effectiveness factor of spherical catalyst pellet and the Thiele modulus were also discussed. The bulk temperature and pellet size have significant effects on the reactivity, while the pressure shows only a slight influence on the reactivity. The internal diffusion effectiveness factor decreases with an increasing Thiele modulus.
基金supported by the National Natural Science Foundation of China(21073238)the National Basic Research Program of China (2011CB211704)the Natural Science Foundation of Hubei Province (2009CDA049)
文摘Silica nanotubes(SNT) have been synthesized using carbon nanotubes(CNT) as a template.Silica-coated carbon nanotubes(SNT-CNT) and SNT were loaded with a cobalt catalyst for use in Fischer-Tropsch synthesis(FTS).The catalysts were prepared by incipient wetness impregnation and characterized by N2 physisorption,X-ray diffraction(XRD),hydrogen temperature programmed reduction(H2-TPR) and transmission electron microscopy(TEM).FTS performance was evaluated in a fixed-bed reactor at 493 K and 1.0 MPa.Co/CNT and Co/SNT catalysts showed higher activity than Co/SNT-CNT in FTS because of the smaller cobalt particle size,higher dispersion and stronger reducibility.The results also showed that structure of the support affects the product selectivity in FTS.The synergistic effects of cobalt particle size,catalytic activity and diffusion limitations as a consequence of its small average pore size lead to medium selectivity to C5+ hydrocarbons and CH4 over Co/SNT-CNT.On the other hand,the Co/CNT showed higher CH4 selectivity and lower C5+ selectivity than Co/SNT,due to its smaller average pore size and cobalt particle size.
