A model for a bubble column slurry reactor is developed based on the experiment of Rhenpreussen Koppers demonstration plant for slurry phase Fischer-Tropsch synthesis reported by Koelble et al. This model is applicabl...A model for a bubble column slurry reactor is developed based on the experiment of Rhenpreussen Koppers demonstration plant for slurry phase Fischer-Tropsch synthesis reported by Koelble et al. This model is applicable to the operation in the churn-turbulent regime and incorporates the information on the bubble size. The axial dispersion model is adopted to describe the flow characteristics of the Fischer-Tropsch slurry reactor. With the model developed, simulations are performed to identify the steady state behavior of a Fischer-Tropsch slurry reactor of commercial size. Predictions of the two-bubble class model is compared with that of the conventional single- bubble class model. The results show that under a variety of conditions, the two-bubble class model gives results different from those for the single-bubble class model.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
A brief review of Fischer-Tropsch synthesis specially in slurry reactors is presented, covering reaction kinetics, activity and selectivity of catalysts, product distribution, effects of process parameters, mass trans...A brief review of Fischer-Tropsch synthesis specially in slurry reactors is presented, covering reaction kinetics, activity and selectivity of catalysts, product distribution, effects of process parameters, mass transfer and solubility of gas. Some important aspects of further research are proposed for improving both theories and production.展开更多
Photocatalytic reduction of carbon monoxide(CO)is a promising route to the production of high-value chemicals and fuels,as a supplement to high energy-input Fischer-Tropsch synthesis(FTS)and a key step in direct photo...Photocatalytic reduction of carbon monoxide(CO)is a promising route to the production of high-value chemicals and fuels,as a supplement to high energy-input Fischer-Tropsch synthesis(FTS)and a key step in direct photo/electro-reduction CO_(2) to multi-carbon products.However,many current research efforts for high-efficiency FTS/CO_(2) reduction mainly focus on the metal-based catalysts,while metal-free and solar-driven photocatalysts are rarely explored.Here,by means of Lewis acid sites,a metal-free composite photocatalyst for CO reduction,namely boron(B)doped-graphene/g-C_(3)N_(4) heterostructure,is proposed.First-principles calculations show that the dopants(B)as catalytic sites can effectively capture and activate CO molecules and reduce CO to CH_(3)OH and CH_(4) in different doping content.It is worth noting that C_(2) products,i.e.,C_(2)H_(5)OH,can be produced with low free energy barriers on paradoped graphene/g-C_(3)N_(4).Meanwhile,the competitive hydrogen evolution reaction(HER)can be greatly suppressed,leading to the high selectivity of CO reduction.Moreover,the formation of a built-in electric field in heterostructure enhances the separation of photogenerated electrons and holes,which further accelerates the transmission of photogenerated electrons to the catalytic sites and improves the reaction efficiency.Overall,this work not only proposes a new strategy from a new perspective to solve problems of high energy consumption and low selectivity of FTS,but also provides a tandem strategy to solve problems of CO_(2) to multi-carbon products.展开更多
文摘A model for a bubble column slurry reactor is developed based on the experiment of Rhenpreussen Koppers demonstration plant for slurry phase Fischer-Tropsch synthesis reported by Koelble et al. This model is applicable to the operation in the churn-turbulent regime and incorporates the information on the bubble size. The axial dispersion model is adopted to describe the flow characteristics of the Fischer-Tropsch slurry reactor. With the model developed, simulations are performed to identify the steady state behavior of a Fischer-Tropsch slurry reactor of commercial size. Predictions of the two-bubble class model is compared with that of the conventional single- bubble class model. The results show that under a variety of conditions, the two-bubble class model gives results different from those for the single-bubble class model.
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.
文摘A brief review of Fischer-Tropsch synthesis specially in slurry reactors is presented, covering reaction kinetics, activity and selectivity of catalysts, product distribution, effects of process parameters, mass transfer and solubility of gas. Some important aspects of further research are proposed for improving both theories and production.
基金supported by the National Natural Science Foundation of China(22033002,21525311,21773027,21703032,and 21973011)the China Postdoctoral Science Foundation(2020M681450)。
文摘Photocatalytic reduction of carbon monoxide(CO)is a promising route to the production of high-value chemicals and fuels,as a supplement to high energy-input Fischer-Tropsch synthesis(FTS)and a key step in direct photo/electro-reduction CO_(2) to multi-carbon products.However,many current research efforts for high-efficiency FTS/CO_(2) reduction mainly focus on the metal-based catalysts,while metal-free and solar-driven photocatalysts are rarely explored.Here,by means of Lewis acid sites,a metal-free composite photocatalyst for CO reduction,namely boron(B)doped-graphene/g-C_(3)N_(4) heterostructure,is proposed.First-principles calculations show that the dopants(B)as catalytic sites can effectively capture and activate CO molecules and reduce CO to CH_(3)OH and CH_(4) in different doping content.It is worth noting that C_(2) products,i.e.,C_(2)H_(5)OH,can be produced with low free energy barriers on paradoped graphene/g-C_(3)N_(4).Meanwhile,the competitive hydrogen evolution reaction(HER)can be greatly suppressed,leading to the high selectivity of CO reduction.Moreover,the formation of a built-in electric field in heterostructure enhances the separation of photogenerated electrons and holes,which further accelerates the transmission of photogenerated electrons to the catalytic sites and improves the reaction efficiency.Overall,this work not only proposes a new strategy from a new perspective to solve problems of high energy consumption and low selectivity of FTS,but also provides a tandem strategy to solve problems of CO_(2) to multi-carbon products.
