The acidities of different Si O2/Al2O3 ratio ZSM-5 zeolites, CBV3024 E, CBV5524 G and CBV8014 were investigated with temperature-programmed desorption of ammonia and diffuse reflectance infrared Fourier transform spec...The acidities of different Si O2/Al2O3 ratio ZSM-5 zeolites, CBV3024 E, CBV5524 G and CBV8014 were investigated with temperature-programmed desorption of ammonia and diffuse reflectance infrared Fourier transform spectroscopy, and their catalytic performances were evaluated to screen the optimal CBV8014 catalyst for ethylene oligomerization. The mesoporosity development in CBV8014 zeolite was conducted by desilication in alkaline medium. The porous characteristics, structural properties and acidic properties of parent and alkali-treated CBV8014 zeolites were studied, and their catalytic performances were evaluated, indicating that CBV8014 treated by 0.2 mol/L NaO H solution has an appropriate mesoporosity development, well preservation of catalyst acidity and crystallinity, good catalytic activity and stability, and high liquid fuel yield for ethylene oligomerization. The effect of reaction pressure on ethylene oligomerization over 0.2HZ catalyst was also investigated, and JP-8 likely hydrocarbon jet fuel was obtained by using 0.2HZ catalyst at 0.344 75 MPa with a high catalyst stability and high liquid yield.展开更多
Developing carbon-based supercapacitors with high rate capability is of great importance to meet the emerging demands for devices that requires high energy density as well as high power density.However,it is hard to f...Developing carbon-based supercapacitors with high rate capability is of great importance to meet the emerging demands for devices that requires high energy density as well as high power density.However,it is hard to fabricate a nanocarbon with high electro-active surface area meanwhile maintaining superior conductivity to ensure the high rate capability since excellent conductivity is usually realized by high temperature graphitization,which would lead to the structural collapse and sintering resulting in low surface area.Herein,we reported a highly porous graphitic carbon nanosheet with an unprecedented rate capability of 98%of its initial capacitance from 0.5 to 50 A/g for ultrahigh-rate supercapacitive energy storage.These hierarchical mesoporous carbon nanosheets(HMCN)were fabricated by a template induced catalytic graphitization approach,in which sheet-like Mg(OH)_(2) was employed as catalytic template in situ catalytically polymerizing of catechol and formaldehyde and catalytically graphitizing of the formed carbon skeleton.Upon the co-effect of template(avoiding the sintering)and the deoxygenation(creating the pores)during the high temperature graphitization process,the obtained HMCN material possesses nanosheet morphology with highly porous graphitic microstructure rich in mesoporosity,large in surface area(2316 m^(2)/g),large in pore volume(3.58 cm^(3)/g)and excellent in conductivity(109.8 S/cm).In 1.0 M TEABF_(4)/AN,HMCN exhibits superior supercapacitive performance including large energy density of 52.2 Wh/kg at high power density of 118 k W/kg,long-cycling stability and excellent rate capability,making HMCN a promising electrode material for supercapacitor devices.展开更多
文摘The acidities of different Si O2/Al2O3 ratio ZSM-5 zeolites, CBV3024 E, CBV5524 G and CBV8014 were investigated with temperature-programmed desorption of ammonia and diffuse reflectance infrared Fourier transform spectroscopy, and their catalytic performances were evaluated to screen the optimal CBV8014 catalyst for ethylene oligomerization. The mesoporosity development in CBV8014 zeolite was conducted by desilication in alkaline medium. The porous characteristics, structural properties and acidic properties of parent and alkali-treated CBV8014 zeolites were studied, and their catalytic performances were evaluated, indicating that CBV8014 treated by 0.2 mol/L NaO H solution has an appropriate mesoporosity development, well preservation of catalyst acidity and crystallinity, good catalytic activity and stability, and high liquid fuel yield for ethylene oligomerization. The effect of reaction pressure on ethylene oligomerization over 0.2HZ catalyst was also investigated, and JP-8 likely hydrocarbon jet fuel was obtained by using 0.2HZ catalyst at 0.344 75 MPa with a high catalyst stability and high liquid yield.
基金financially supported by the National Science Foundation of China(22172073 and 21773112)the Fundamental Research Funds for the Central Universitiesthe Science and Technology Innovation Team Plan for the youths in universities of Hubei province(T2020021)。
文摘Developing carbon-based supercapacitors with high rate capability is of great importance to meet the emerging demands for devices that requires high energy density as well as high power density.However,it is hard to fabricate a nanocarbon with high electro-active surface area meanwhile maintaining superior conductivity to ensure the high rate capability since excellent conductivity is usually realized by high temperature graphitization,which would lead to the structural collapse and sintering resulting in low surface area.Herein,we reported a highly porous graphitic carbon nanosheet with an unprecedented rate capability of 98%of its initial capacitance from 0.5 to 50 A/g for ultrahigh-rate supercapacitive energy storage.These hierarchical mesoporous carbon nanosheets(HMCN)were fabricated by a template induced catalytic graphitization approach,in which sheet-like Mg(OH)_(2) was employed as catalytic template in situ catalytically polymerizing of catechol and formaldehyde and catalytically graphitizing of the formed carbon skeleton.Upon the co-effect of template(avoiding the sintering)and the deoxygenation(creating the pores)during the high temperature graphitization process,the obtained HMCN material possesses nanosheet morphology with highly porous graphitic microstructure rich in mesoporosity,large in surface area(2316 m^(2)/g),large in pore volume(3.58 cm^(3)/g)and excellent in conductivity(109.8 S/cm).In 1.0 M TEABF_(4)/AN,HMCN exhibits superior supercapacitive performance including large energy density of 52.2 Wh/kg at high power density of 118 k W/kg,long-cycling stability and excellent rate capability,making HMCN a promising electrode material for supercapacitor devices.
