A series of meso‐microporous copper‐supporting chabazite molecular sieve（CuSAPO‐34） catalysts with excellent performance in low‐temperature ammonia selective catalytic reduction（NH3‐SCR）have been synthesized ...A series of meso‐microporous copper‐supporting chabazite molecular sieve（CuSAPO‐34） catalysts with excellent performance in low‐temperature ammonia selective catalytic reduction（NH3‐SCR）have been synthesized via a one‐pot hydrothermal crystallization method. The physicochemical properties of the catalysts were characterized by scanning electron microscopy, transmission electron microscopy, N2 adsorption‐desorption measurements, X‐ray diffraction, 27 Al magic angle spinning nuclear magnetic resonance, diffuse reflectance ultraviolet‐visible spectroscopy, inductively coupled plasma‐atomic emission spectroscopy, X‐ray photoelectron spectroscopy, temperature‐programmed reduction measurements, and electron paramagnetic resonance analysis. The formation of micro‐mesopores in the Cu‐SAPO‐34 catalysts decreases diffusion resistance and greatly improves the accessibility of reactants to catalytic active sites. The main active sites for NH3‐SCR reaction are the isolated Cu^2＋ species displaced into the ellipsoidal cavity of the Cu‐SAPO‐34 catalysts.展开更多
Catalytic dehydrogenation represents one of the most effective methods for converting low-carbon hydrocarbons into monoolefins and hydrogen with identical carbon numbers.In this study,microporous(HZSMi)and meso-microp...Catalytic dehydrogenation represents one of the most effective methods for converting low-carbon hydrocarbons into monoolefins and hydrogen with identical carbon numbers.In this study,microporous(HZSMi)and meso-microporous molecular sieves(HZSMu)with a Si/Al atomic ratio of 150,synthesized in the laboratory,were prepared via hydrothermal synthesis.These supports were impregnated with 2.4%Co using the incipient wetness impregnation method and subsequently modified by introducing the metal additives Zr and Sn.Notably,the Co-Sn/HZSMu catalyst exhibited the highest stability,achieving a propylene selectivity of 95.3% within 400 min while maintaining robust activity.A series of characterization analyses reveal that the HZSMu molecular sieve possesses distinctive weaving properties.The synergistic effect between mesopores facilitates the adsorption and activation of reactants while preventing pore blockage,thus promoting the rapid diffusion of reactants on its surface.The incorporation of the metal additive Sn promotes the uniform dispersion of Co,mitigating the occurrence of side reactions and enhancing the catalytic performance and reaction stability of the catalyst.展开更多
Lithium-sulfur(Li-S) batteries are promising energy-storage devices for future generations of portable electronics and electric vehicles because of the outstanding energy density,low cost,and nontoxic nature of S.In t...Lithium-sulfur(Li-S) batteries are promising energy-storage devices for future generations of portable electronics and electric vehicles because of the outstanding energy density,low cost,and nontoxic nature of S.In the past decades,various novel electrodes and electrolytes have been studied to improve the performance of Li-S batteries.However,the very limited lifespan and rate performance of Li-S batteries originating from the dissolution and diffusion of long-chain polysulfides in liquid electrolytes,and the intrinsic poor conductivity of S severely hinder their practical application.Herein,an electrospinning method was developed to fabricate a thin conductive interlayer consisting of meso-/microporous N/O dual-doping carbon nanofiber(CNF).The freestanding 3 D interwoven structure with conductive pathways for electrons and ions can enhance the contact between polysulfides and N/O atoms to realize the highly robust trapping of polysulfides via the extremely polar interaction.Consequently,combining the meso-microporous N/O dual-doping CNF interlayer with a monodispersed S nanoparticle cathode results in a superior electrochemical performance of 862.5 mAh/g after 200 cycles at 0.2 C and a cycle decay as low as 0.08% per cycle.An area specific capacity of 5.22 mAh/cm^(2) can be obtained after 100 cycles at 0.1 C with a high S loading of 7.5 mg/cm^(2).展开更多
基金supported by the National Natural Science Foundation of China(2137626121173270)+4 种基金the National High Technology Research and Development Program of China(863 Program2015AA034603)the Beijing Natural Science Foundation(2142027)the China University of Petroleum Fund(201300071100072462015QZDX04)~~
文摘A series of meso‐microporous copper‐supporting chabazite molecular sieve（CuSAPO‐34） catalysts with excellent performance in low‐temperature ammonia selective catalytic reduction（NH3‐SCR）have been synthesized via a one‐pot hydrothermal crystallization method. The physicochemical properties of the catalysts were characterized by scanning electron microscopy, transmission electron microscopy, N2 adsorption‐desorption measurements, X‐ray diffraction, 27 Al magic angle spinning nuclear magnetic resonance, diffuse reflectance ultraviolet‐visible spectroscopy, inductively coupled plasma‐atomic emission spectroscopy, X‐ray photoelectron spectroscopy, temperature‐programmed reduction measurements, and electron paramagnetic resonance analysis. The formation of micro‐mesopores in the Cu‐SAPO‐34 catalysts decreases diffusion resistance and greatly improves the accessibility of reactants to catalytic active sites. The main active sites for NH3‐SCR reaction are the isolated Cu^2＋ species displaced into the ellipsoidal cavity of the Cu‐SAPO‐34 catalysts.
基金supported by the National Natural Science Foundation of China(Grant No.21968034).
文摘Catalytic dehydrogenation represents one of the most effective methods for converting low-carbon hydrocarbons into monoolefins and hydrogen with identical carbon numbers.In this study,microporous(HZSMi)and meso-microporous molecular sieves(HZSMu)with a Si/Al atomic ratio of 150,synthesized in the laboratory,were prepared via hydrothermal synthesis.These supports were impregnated with 2.4%Co using the incipient wetness impregnation method and subsequently modified by introducing the metal additives Zr and Sn.Notably,the Co-Sn/HZSMu catalyst exhibited the highest stability,achieving a propylene selectivity of 95.3% within 400 min while maintaining robust activity.A series of characterization analyses reveal that the HZSMu molecular sieve possesses distinctive weaving properties.The synergistic effect between mesopores facilitates the adsorption and activation of reactants while preventing pore blockage,thus promoting the rapid diffusion of reactants on its surface.The incorporation of the metal additive Sn promotes the uniform dispersion of Co,mitigating the occurrence of side reactions and enhancing the catalytic performance and reaction stability of the catalyst.
基金the support from the National Key Research and Development Program(No.2018YFB1107500)the Liao Ning Revitalization Talents Program(No.XLYC1907144)+1 种基金the National Natural Science Foundation of China(No.51503024)the Dalian Youth Science and Technology Star Project Support Program(No.2017RQ104)。
文摘Lithium-sulfur(Li-S) batteries are promising energy-storage devices for future generations of portable electronics and electric vehicles because of the outstanding energy density,low cost,and nontoxic nature of S.In the past decades,various novel electrodes and electrolytes have been studied to improve the performance of Li-S batteries.However,the very limited lifespan and rate performance of Li-S batteries originating from the dissolution and diffusion of long-chain polysulfides in liquid electrolytes,and the intrinsic poor conductivity of S severely hinder their practical application.Herein,an electrospinning method was developed to fabricate a thin conductive interlayer consisting of meso-/microporous N/O dual-doping carbon nanofiber(CNF).The freestanding 3 D interwoven structure with conductive pathways for electrons and ions can enhance the contact between polysulfides and N/O atoms to realize the highly robust trapping of polysulfides via the extremely polar interaction.Consequently,combining the meso-microporous N/O dual-doping CNF interlayer with a monodispersed S nanoparticle cathode results in a superior electrochemical performance of 862.5 mAh/g after 200 cycles at 0.2 C and a cycle decay as low as 0.08% per cycle.An area specific capacity of 5.22 mAh/cm^(2) can be obtained after 100 cycles at 0.1 C with a high S loading of 7.5 mg/cm^(2).
