Hydrothermally synthesized mixed-phase MoVTeNbO_(x) catalysts are active for catalyzing the selective oxidation of propane to acrylic acid but suffer from the presence of the amorphous phase and low specific surface a...Hydrothermally synthesized mixed-phase MoVTeNbO_(x) catalysts are active for catalyzing the selective oxidation of propane to acrylic acid but suffer from the presence of the amorphous phase and low specific surface areas.Herein we report that HCl treatment preferentially y dissolves the amorphous phase in hydrothermally synthesized mixed-phase MoVTeNbO_(x) catalysts and increases the catalytic performance.An optimal HCl treatment significantly increases the C3H8 conversion from 38.9%to 58.2% without changing the acrylic acid selectivity in the selective oxidation of propane to acrylic acid at 380°C.The original and HCl treated catalysts exhibit similar apparent activation energies,while HCl treatment increases the specific surface area,surface acid sites,surface V^(5+) density,and C_(3)H_(8) and C_(3)H_(6) irreversible adsorption amounts but decreases the C_(3)H_(8) and C_(3)H_(6) irreversible adsorption heats. The C_(3)H_(8) conversion rate is proportional to the surface V^(5+) density and C_(3)H_(8) irreversible adsorption amount, and the TOF is measured as 3.31 ± 0.08×10^(-5) s^(-1) at 340°C. Thus,HCl treatment enhances the catalytic performance of mixed-phase MoVTeNbO_(x) catalysts mainly by increasing the active site density rather than by increasing the active site activity. Our results provide an effective approach to prepare highly active mixed-phase MoVTeNbO_(x) catalysts for the selective oxidation of propane to acrylic acid.展开更多
Selective oxidation of propane to acetone(AC)with H_(2) and O_(2) provides a direct route to convert low-cost propane into valueadded products.Unfortunately,the catalytic activity of conventional Au/Ti-based catalysts...Selective oxidation of propane to acetone(AC)with H_(2) and O_(2) provides a direct route to convert low-cost propane into valueadded products.Unfortunately,the catalytic activity of conventional Au/Ti-based catalysts is constrained by the high energy barrier for H_(2) dissociation.Herein,uncalcined TS-1 supported Au-Pd bimetallic catalysts were prepared,and the relationship between the active-site structure and corresponding performance in the selective oxidation of propane with H_(2) and O_(2) in the gas phase was systematically investigated.In contrast to the liquid-phase reaction,trace Pd alloyed with Au triggered an increase in both catalytic activity and selectivity,in which Au_(20)-Pd_(1)/TS-1-B catalyst exhibited excellent activity(170 gAC·h^(−1)·kgcat^(−1))and AC selectivity(90.6%),much higher than those of the Au/TS-1-B catalyst(AC formation rate of 100 gAC·h^(−1)·kgcat^(−1)and AC selectivity of 86.3%).It was found that Pd was gradually isolated into monomers with the increase of Au/Pd molar ratio,and the synergy between Pd single atoms and Au improved the catalytic performance via enhancing hydrogen dissociation and modulating the electronic structure of Au.Furthermore,the reaction conditions were optimized based on the kinetics studies and the Au_(20)-Pd_(1)/TS-1-B catalyst exhibited enhanced H_(2) selectivity(45%)and long-term stability(over 130 h).The insights gained here can offer valuable guidance for the design of Au-Pd catalysts applicable to other gas-phase oxidation reactions.展开更多
基金the National Key R&D Program of MOST(2021YFA1501301)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0450102)+2 种基金the National Natural Science Foundation of China(22202189)the Changjiang Scholars Program of Ministry of Education of Chinathe Instruments Center for Physical Science,University of Science and Technology of China.
文摘Hydrothermally synthesized mixed-phase MoVTeNbO_(x) catalysts are active for catalyzing the selective oxidation of propane to acrylic acid but suffer from the presence of the amorphous phase and low specific surface areas.Herein we report that HCl treatment preferentially y dissolves the amorphous phase in hydrothermally synthesized mixed-phase MoVTeNbO_(x) catalysts and increases the catalytic performance.An optimal HCl treatment significantly increases the C3H8 conversion from 38.9%to 58.2% without changing the acrylic acid selectivity in the selective oxidation of propane to acrylic acid at 380°C.The original and HCl treated catalysts exhibit similar apparent activation energies,while HCl treatment increases the specific surface area,surface acid sites,surface V^(5+) density,and C_(3)H_(8) and C_(3)H_(6) irreversible adsorption amounts but decreases the C_(3)H_(8) and C_(3)H_(6) irreversible adsorption heats. The C_(3)H_(8) conversion rate is proportional to the surface V^(5+) density and C_(3)H_(8) irreversible adsorption amount, and the TOF is measured as 3.31 ± 0.08×10^(-5) s^(-1) at 340°C. Thus,HCl treatment enhances the catalytic performance of mixed-phase MoVTeNbO_(x) catalysts mainly by increasing the active site density rather than by increasing the active site activity. Our results provide an effective approach to prepare highly active mixed-phase MoVTeNbO_(x) catalysts for the selective oxidation of propane to acrylic acid.
基金supported by the Ministry of Science and Technology of the People’s Republic of China under the Research Fund for National Key Research and Development Program of China(No.2021YFA1501403)the National Natural Science Foundation of China(Nos.22208093,22038003,and 22178100)+2 种基金the Shanghai Science and Technology Innovation Action Plan(No.22JC1403800)the Innovation Program of the Shanghai Municipal Education Commission,the Program of Shanghai Academic/Technology Research Leader(No.21XD1421000)the Fundamental Research Funds for the Central Universities.
文摘Selective oxidation of propane to acetone(AC)with H_(2) and O_(2) provides a direct route to convert low-cost propane into valueadded products.Unfortunately,the catalytic activity of conventional Au/Ti-based catalysts is constrained by the high energy barrier for H_(2) dissociation.Herein,uncalcined TS-1 supported Au-Pd bimetallic catalysts were prepared,and the relationship between the active-site structure and corresponding performance in the selective oxidation of propane with H_(2) and O_(2) in the gas phase was systematically investigated.In contrast to the liquid-phase reaction,trace Pd alloyed with Au triggered an increase in both catalytic activity and selectivity,in which Au_(20)-Pd_(1)/TS-1-B catalyst exhibited excellent activity(170 gAC·h^(−1)·kgcat^(−1))and AC selectivity(90.6%),much higher than those of the Au/TS-1-B catalyst(AC formation rate of 100 gAC·h^(−1)·kgcat^(−1)and AC selectivity of 86.3%).It was found that Pd was gradually isolated into monomers with the increase of Au/Pd molar ratio,and the synergy between Pd single atoms and Au improved the catalytic performance via enhancing hydrogen dissociation and modulating the electronic structure of Au.Furthermore,the reaction conditions were optimized based on the kinetics studies and the Au_(20)-Pd_(1)/TS-1-B catalyst exhibited enhanced H_(2) selectivity(45%)and long-term stability(over 130 h).The insights gained here can offer valuable guidance for the design of Au-Pd catalysts applicable to other gas-phase oxidation reactions.
