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 MoVTeNbOx 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
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 MoVTeNbOx 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.
