The Fischer–Tropsch to olefins（FTO） process is a method for the direct conversion of synthesis gas to lower C–Colefins. Carbon-supported iron carbide nanoparticles are attractive catalysts for this reaction.The ca...The Fischer–Tropsch to olefins（FTO） process is a method for the direct conversion of synthesis gas to lower C–Colefins. Carbon-supported iron carbide nanoparticles are attractive catalysts for this reaction.The catalytic activity can be improved and undesired formation of alkanes can be suppressed by the addition of sodium and sulfur as promoters but the influence of their content and ratio remains poorly understood and the promoted catalysts often suffer from rapid deactivation due to particle growth. A series of carbon black-supported iron catalysts with similar iron content and nominal sodium/sulfur loadings of 1–30/0.5–5 wt% with respect to iron are prepared and characterized under FTO conditions at 1and 10 bar syngas pressure to illuminate the influence of the promoter level on the catalytic properties.Iron particles and promoters undergo significant reorganization during FTO operation under industrially relevant conditions. Low sodium content（1–3 wt%） leads to a delay in iron carbide formation. Sodium contents of 15–30 wt% lead to rapid loss of catalytic activity due to the covering of the iron surface with promoters during particle growth under FTO operation. Higher activity and slower loss of activity are observed at low promoter contents（1–3 wt% sodium and 0.5–1 wt% sulfur） but a minimum amount of alkali is required to effectively suppress methane and C–Cparaffin formation. A reference catalyst support（carbide-derived carbon aerogel） shows that the optimum promoter level depends on iron particle size and support pore structure.展开更多
K-promoted iron/carbon nanotubes composite（i.e., Fe K-OX） was prepared by a redox reaction between carbon nanotubes and K2FeO4followed by thermal treatments on a purpose as the Fischer–Tropsch catalyst for the dire...K-promoted iron/carbon nanotubes composite（i.e., Fe K-OX） was prepared by a redox reaction between carbon nanotubes and K2FeO4followed by thermal treatments on a purpose as the Fischer–Tropsch catalyst for the direct conversion of syngas to lower olefins. Its catalytic behaviors were compared with those of the other two Fe-IM and Fe K-IM catalysts prepared by impregnation method followed by thermal treatments. The novel Fe K-OX composite catalyst is found to exhibit higher hydrocarbon selectivity,lower olefins selectivity and chain growth probability as well as better stability. The catalyst structureperformance relationship has been established using multiple techniques including XRD, Raman, TEM and EDS elemental mapping. In addition, effects of additional potassium into the Fe K-OX composite catalyst on the FTO performance were also investigated and discussed. Additional potassium promoters further endow the catalysts with higher yield of lower olefins. These results demonstrated that the introduction method of promoters and iron species plays a crucial role in the design and fabrication of highly active,selective and stable iron-based composite catalysts for the FTO reaction.展开更多
Bis(8-quinolinolato)zirconium dichloride (Ox)2ZrCl2 (Ox- = 8-quinolinolato) was found active for ethylene oligomerization with a high selectivity of 84~94% to C4~C10 olefins at 70~100C under the pressure of 1.8 MPa us...Bis(8-quinolinolato)zirconium dichloride (Ox)2ZrCl2 (Ox- = 8-quinolinolato) was found active for ethylene oligomerization with a high selectivity of 84~94% to C4~C10 olefins at 70~100C under the pressure of 1.8 MPa using Et2AlCl as a co-catalyst (Al/Zr = 60).展开更多
A reaction-coupling strategy is often employed for CO_(2)hydrogenation to produce fuels and chemicals using oxide/zeolite bifunctional catalysts.Because the oxide components are responsible for CO_(2)activation,unders...A reaction-coupling strategy is often employed for CO_(2)hydrogenation to produce fuels and chemicals using oxide/zeolite bifunctional catalysts.Because the oxide components are responsible for CO_(2)activation,understanding the structural effects of these oxides is crucial,however,these effects still remain unclear.In this study,we combined In_(2)O_(3),with varying particle sizes,and SAPO‐34 as bifunctional catalysts for CO_(2)hydrogenation.The CO_(2)conversion and selectivity of the lower olefins increased as the average In_(2)O_(3)crystallite size decreased from 29 to 19 nm;this trend mainly due to the increasing number of oxygen vacancies responsible for CO_(2) and H_(2) activation.However,In_(2)O_(3)particles smaller than 19 nm are more prone to sintering than those with other sizes.The results suggest that 19 nm is the optimal size of In_(2)O_(3)for CO_(2)hydrogenation to lower olefins and that the oxide particle size is crucial for designing catalysts with high activity,high selectivity,and high stability.展开更多
This paper tried to develop the optimum procedure for microencapsulating water soluble solid powder with the thermal responsible material by the melting dispersion cooling method. Sodium hydrogen carbonate was adopted...This paper tried to develop the optimum procedure for microencapsulating water soluble solid powder with the thermal responsible material by the melting dispersion cooling method. Sodium hydrogen carbonate was adopted as a water soluble solid powder instead of microencapsulating carbon dioxide gas. The shell material was composed of olefin wax and α-tocopherol. In the experiment, the concentration of oil soluble surfactant and the water soluble surfactant species were changed. Sodium hydrogen carbonate was treated in the aqueous solution dissolving the water soluble surfactant to form the finer sodium hydrogen carbonate powder and to increase the content. The microencapsulation efficiency could be increased with the concentration of oil soluble surfactant and considerably increased by treating sodium hydrogen carbonate with the water soluble surfactant. Sodium hydrogen carbonate was protected well from environmental water. The microcapsules showed the thermal responsibility to generate carbon dioxide.展开更多
Recently, as a direct consequence of the dwindling world oil reserves and the growing awareness of the environmental problems associated with the use of coal as energy source, there is growing interest in cheaper, abu...Recently, as a direct consequence of the dwindling world oil reserves and the growing awareness of the environmental problems associated with the use of coal as energy source, there is growing interest in cheaper, abundant and cleaner burning methane. The Gas-to-Liquid technology offers perhaps the most attractive routes for the exploitation of the world huge and growing natural gas resources. Using this process the erstwhile stranded gas is converted to premium grade liquid fuels and chemicals that are easily transported. However, a widespread application of the GTL process is being hampered by economical and technical challenges. The high cost of synthesis gas, for instance, weighs heavily on the economics and competitiveness of the process limiting its wider application. This work presented a modified Gas-to-Liquid process that eliminates the costly synthesis gas production step. The proposed process utilized an alternative pathway for methane activation via the production of chloromethane derivatives which are then converted to hydrocarbons. It established that hydrocarbons mainly olefins can be economically produced from di- and tri-chloro- methanes over a typical iron-based Fischer Tropsch catalysts in a moving bed reactor at industrially relevant conditions. Some of the attractions of the proposed process include a) the elimination of the costly air separation plant requirement b) high process selectivity and c) significant reduction of carbon dioxide emissions thereby saving on feedstock loss and the costly CO2 removal and isolation processes.展开更多
FTO(Fischer-Tropsch to olefins)作为合成气制备低碳烯烃(C_(2)^(=)~C_(4)^(=))的代替路径在工业上具有重要意义。CoMnNa作为FTO反应催化剂而备受关注,但由于反应过程中CO_(2)C活性相的形成,导致CO_(2)选择性较高。引入AlO(OH)载体,制...FTO(Fischer-Tropsch to olefins)作为合成气制备低碳烯烃(C_(2)^(=)~C_(4)^(=))的代替路径在工业上具有重要意义。CoMnNa作为FTO反应催化剂而备受关注,但由于反应过程中CO_(2)C活性相的形成,导致CO_(2)选择性较高。引入AlO(OH)载体,制备了Co_(1)Mn_(1)Na/AlO(OH)催化剂,通过XRD、STEM、EDX-mapping、N_(2)吸附-脱附等温线、孔径分布曲线对催化剂进行了表征,通过H_(2)-TPR对催化剂的还原性进行了分析,并对催化剂的FTO反应性能进行了评价。结果表明,利用载体与CoMn的相互作用,降低了CoMn氧化物的还原性,有效抑制了CoMn中Co的析出及CO_(2)C的形成,减少了CoMn体系中Co和CO_(2)C活性相;在低碳烯烃选择性高达32.4%的情况下,成功将CO_(2)选择性降至10%以下。展开更多
Iron particles confined in carbon nanotube (CNT) channels have been used as a catalyst for the direct conversion of syngas to light olefins.Compared with iron catalysts supported on other materials such as Silica-1,SB...Iron particles confined in carbon nanotube (CNT) channels have been used as a catalyst for the direct conversion of syngas to light olefins.Compared with iron catalysts supported on other materials such as Silica-1,SBA-15 and carbon black,the CNT-confined catalyst exhibits a higher CO conversion and selectivity to the light olefins.This can be attributed to the CNT channels,which provide a unique confinement environment for iron particles.展开更多
基金supported by a Post Doc grant of the German Academic Exchange Service(Deutscher Akademischer Austauschdienst,DAAD grant no.91552012)by the European Research Council(EU FP7 ERC advanced grant no.338846)
文摘The Fischer–Tropsch to olefins（FTO） process is a method for the direct conversion of synthesis gas to lower C–Colefins. Carbon-supported iron carbide nanoparticles are attractive catalysts for this reaction.The catalytic activity can be improved and undesired formation of alkanes can be suppressed by the addition of sodium and sulfur as promoters but the influence of their content and ratio remains poorly understood and the promoted catalysts often suffer from rapid deactivation due to particle growth. A series of carbon black-supported iron catalysts with similar iron content and nominal sodium/sulfur loadings of 1–30/0.5–5 wt% with respect to iron are prepared and characterized under FTO conditions at 1and 10 bar syngas pressure to illuminate the influence of the promoter level on the catalytic properties.Iron particles and promoters undergo significant reorganization during FTO operation under industrially relevant conditions. Low sodium content（1–3 wt%） leads to a delay in iron carbide formation. Sodium contents of 15–30 wt% lead to rapid loss of catalytic activity due to the covering of the iron surface with promoters during particle growth under FTO operation. Higher activity and slower loss of activity are observed at low promoter contents（1–3 wt% sodium and 0.5–1 wt% sulfur） but a minimum amount of alkali is required to effectively suppress methane and C–Cparaffin formation. A reference catalyst support（carbide-derived carbon aerogel） shows that the optimum promoter level depends on iron particle size and support pore structure.
基金supported by the China Scholarship Council (CSC) for the research at Norwegian University of Science and Technologysupported by the Natural Science Foundation of China (21306046)+2 种基金the Open Project of State Key Laboratory of Chemical Engineering (SKL-Che-15C03)the Fundamental Research Funds for the Central Universities (WA1514013)the 111 Project of Ministry of Education of China (B08021)
文摘K-promoted iron/carbon nanotubes composite（i.e., Fe K-OX） was prepared by a redox reaction between carbon nanotubes and K2FeO4followed by thermal treatments on a purpose as the Fischer–Tropsch catalyst for the direct conversion of syngas to lower olefins. Its catalytic behaviors were compared with those of the other two Fe-IM and Fe K-IM catalysts prepared by impregnation method followed by thermal treatments. The novel Fe K-OX composite catalyst is found to exhibit higher hydrocarbon selectivity,lower olefins selectivity and chain growth probability as well as better stability. The catalyst structureperformance relationship has been established using multiple techniques including XRD, Raman, TEM and EDS elemental mapping. In addition, effects of additional potassium into the Fe K-OX composite catalyst on the FTO performance were also investigated and discussed. Additional potassium promoters further endow the catalysts with higher yield of lower olefins. These results demonstrated that the introduction method of promoters and iron species plays a crucial role in the design and fabrication of highly active,selective and stable iron-based composite catalysts for the FTO reaction.
基金We are gratefully acknowledge the National Natural Science Foundation of China(Grant no.20173006)for financial support of this research
文摘Bis(8-quinolinolato)zirconium dichloride (Ox)2ZrCl2 (Ox- = 8-quinolinolato) was found active for ethylene oligomerization with a high selectivity of 84~94% to C4~C10 olefins at 70~100C under the pressure of 1.8 MPa using Et2AlCl as a co-catalyst (Al/Zr = 60).
文摘A reaction-coupling strategy is often employed for CO_(2)hydrogenation to produce fuels and chemicals using oxide/zeolite bifunctional catalysts.Because the oxide components are responsible for CO_(2)activation,understanding the structural effects of these oxides is crucial,however,these effects still remain unclear.In this study,we combined In_(2)O_(3),with varying particle sizes,and SAPO‐34 as bifunctional catalysts for CO_(2)hydrogenation.The CO_(2)conversion and selectivity of the lower olefins increased as the average In_(2)O_(3)crystallite size decreased from 29 to 19 nm;this trend mainly due to the increasing number of oxygen vacancies responsible for CO_(2) and H_(2) activation.However,In_(2)O_(3)particles smaller than 19 nm are more prone to sintering than those with other sizes.The results suggest that 19 nm is the optimal size of In_(2)O_(3)for CO_(2)hydrogenation to lower olefins and that the oxide particle size is crucial for designing catalysts with high activity,high selectivity,and high stability.
文摘This paper tried to develop the optimum procedure for microencapsulating water soluble solid powder with the thermal responsible material by the melting dispersion cooling method. Sodium hydrogen carbonate was adopted as a water soluble solid powder instead of microencapsulating carbon dioxide gas. The shell material was composed of olefin wax and α-tocopherol. In the experiment, the concentration of oil soluble surfactant and the water soluble surfactant species were changed. Sodium hydrogen carbonate was treated in the aqueous solution dissolving the water soluble surfactant to form the finer sodium hydrogen carbonate powder and to increase the content. The microencapsulation efficiency could be increased with the concentration of oil soluble surfactant and considerably increased by treating sodium hydrogen carbonate with the water soluble surfactant. Sodium hydrogen carbonate was protected well from environmental water. The microcapsules showed the thermal responsibility to generate carbon dioxide.
文摘Recently, as a direct consequence of the dwindling world oil reserves and the growing awareness of the environmental problems associated with the use of coal as energy source, there is growing interest in cheaper, abundant and cleaner burning methane. The Gas-to-Liquid technology offers perhaps the most attractive routes for the exploitation of the world huge and growing natural gas resources. Using this process the erstwhile stranded gas is converted to premium grade liquid fuels and chemicals that are easily transported. However, a widespread application of the GTL process is being hampered by economical and technical challenges. The high cost of synthesis gas, for instance, weighs heavily on the economics and competitiveness of the process limiting its wider application. This work presented a modified Gas-to-Liquid process that eliminates the costly synthesis gas production step. The proposed process utilized an alternative pathway for methane activation via the production of chloromethane derivatives which are then converted to hydrocarbons. It established that hydrocarbons mainly olefins can be economically produced from di- and tri-chloro- methanes over a typical iron-based Fischer Tropsch catalysts in a moving bed reactor at industrially relevant conditions. Some of the attractions of the proposed process include a) the elimination of the costly air separation plant requirement b) high process selectivity and c) significant reduction of carbon dioxide emissions thereby saving on feedstock loss and the costly CO2 removal and isolation processes.
文摘FTO(Fischer-Tropsch to olefins)作为合成气制备低碳烯烃(C_(2)^(=)~C_(4)^(=))的代替路径在工业上具有重要意义。CoMnNa作为FTO反应催化剂而备受关注,但由于反应过程中CO_(2)C活性相的形成,导致CO_(2)选择性较高。引入AlO(OH)载体,制备了Co_(1)Mn_(1)Na/AlO(OH)催化剂,通过XRD、STEM、EDX-mapping、N_(2)吸附-脱附等温线、孔径分布曲线对催化剂进行了表征,通过H_(2)-TPR对催化剂的还原性进行了分析,并对催化剂的FTO反应性能进行了评价。结果表明,利用载体与CoMn的相互作用,降低了CoMn氧化物的还原性,有效抑制了CoMn中Co的析出及CO_(2)C的形成,减少了CoMn体系中Co和CO_(2)C活性相;在低碳烯烃选择性高达32.4%的情况下,成功将CO_(2)选择性降至10%以下。
基金supported by the Ministry of Science and Technology of China (Grant No. 2006CB932703)
文摘Iron particles confined in carbon nanotube (CNT) channels have been used as a catalyst for the direct conversion of syngas to light olefins.Compared with iron catalysts supported on other materials such as Silica-1,SBA-15 and carbon black,the CNT-confined catalyst exhibits a higher CO conversion and selectivity to the light olefins.This can be attributed to the CNT channels,which provide a unique confinement environment for iron particles.
