Engineering unique electronic structure of catalyst to boost catalytic performance is of prime scientific and industrial importance.Herein,the identification of intrinsic electronic sensitivity for direct propene epox...Engineering unique electronic structure of catalyst to boost catalytic performance is of prime scientific and industrial importance.Herein,the identification of intrinsic electronic sensitivity for direct propene epoxidation was first achieved over highly stable Au/wormhole-like TS-1 catalyst.Results show that the electron transfer of Au species can be regulated by manipulating the dynamic evolutions and contents of Au valence states,thus resulting in different catalytic performance in 100 h time-on-stream.By DFT calculations,kinetic analysis and multicharacterizations,it is found that the Au^(0) species with higher electronic population can easily transfer more electrons to activate surface O_(2) compared with Au^(1+) and Au^(3+) species.Moreover,there is a positive correlation between Au^(0) content and activity.Based on this correlation,a facile strategy is further proposed to boost Au^(0) percentage,resulting in the reported highest PO formation rate without adding promoters.This work harbors tremendous guiding significance to the design of highly efficient Au/Ti-containing catalyst for propene epoxidation with H_(2) and O_(2).展开更多
The advocacy of green chemical industry has led to the development of highly efficient catalysts for direct gas-phase propene epoxidation with green,sustainable and simple essence.The S-1/TS-1@dendritic-SiO_(2) materi...The advocacy of green chemical industry has led to the development of highly efficient catalysts for direct gas-phase propene epoxidation with green,sustainable and simple essence.The S-1/TS-1@dendritic-SiO_(2) material with three-layer core–shell structure was developed and used as the support for Au catalysts,which showed simultaneously fantastic PO formation rate,PO selectivity and stability(over 100 h)for propene epoxidation with H_(2) and O_(2).It is found that silicalite-1(S-1)core and the middle thin layer of TS-1 offer great mass transfer ability,which could be responsible for the excellent stability.The designed dendritic SiO_(2) shell covers part of the acid sites on the external surface of TS-1,inhibiting the side reactions and improving the PO selectivity.Furthermore,three kinds of SiO_(2) shell morphologies(i.e.,dendritic,net,mesoporous shell)were designed,and relationship between shell morphology and catalytic performance was elucidated.The results in this paper harbour tremendous guiding significance for the design of highly efficient epoxidation catalysts.展开更多
Propylene oxide plays a pivotal role as an organic synthesis intermediate,boasting extensive downstream applications and promising market prospects.Propene epoxidation via molecular oxygen has garnered considerable at...Propylene oxide plays a pivotal role as an organic synthesis intermediate,boasting extensive downstream applications and promising market prospects.Propene epoxidation via molecular oxygen has garnered considerable attention due to its cost-effectiveness,environmental friendliness,ease of operation,and straightforward product separation.This paper provides an in-depth exploration of recent advance-ments,ranging from nanoparticle to Single-atom catalysts(SACs),in the context of propene epoxidation using molecular oxygen.Conventional nanoparticle catalysts,including those based on Ag,Cu,and other metals,are examined with regard to their contributions to support effects,electron effects,or crystal-plane effects within the mechanistic investigation.Furthermore,emerging SACs(specifically Mo,Cu,and Co)are discussed in terms of synthesis strategies,characterization methods,and mechanism studies.This comprehensive review sheds new light on design strategies,relevant characterizations,and thorough mechanism investigations aimed at fostering the development of efficient catalysts,thereby expediting progress in the industrial implementation of propene epoxidation.展开更多
The direct epoxidation of propylene using H_(2) and O_(2) has emerged as a promising alternative to conventional industrial processes,offering superior atom economy,environmental compatibility,and process economics.Th...The direct epoxidation of propylene using H_(2) and O_(2) has emerged as a promising alternative to conventional industrial processes,offering superior atom economy,environmental compatibility,and process economics.This work demonstrates a facile design strategy to enhance Au-Ti synergy in Au/TS-1 catalysts through precise control of TPAOH/Si ratios during zeolite synthesis.Systematic reduction of TS-1 crystallite dimensions to 220 nm was achieved through TPAOH/Si ratio optimization,simultaneously producing micro-mesoporous hierarchical architectures while preserving crystallinity.The engineered Au/TS-1 catalyst prepared via a deposition-precipitation method exhibited exceptional propylene oxide selectivity(~95%)with stable activity,which is attributed to optimized electronic coupling between Au nanoparticles and framework Ti species.Spectroscopic analyses(XPS/UV-vis)revealed strengthened Au-Ti electronic interactions through positive binding energy shifts(Au 4f_(7/2):+0.4 eV;Ti 2p_(1/2):+0.9 eV),correlating with enhanced propylene activation.The catalytic efficiency was further governed by synergistic effects between accessible Ti-surrounded Au sites and surface silanol density.In situ FT-IR kinetic analysis identified two distinct reaction phases:initial rate-limiting propene chemisorption(0-20 min)followed by steady-state operation(25-55 min),with acetone and propanal identified as primary byproducts.This mechanistic understanding of structure-activity relationships advances fundamental principles for designing high-performance epoxidation catalysts while accelerating industrial implementation of sustainable propylene oxide production routes.展开更多
We report a comprehensive theoretical investigation of the catalytic reaction mechanisms of propene epoxidation on gold nanoclusters using density functional theory （DFT）. We have shown that water acts as a catalyti...We report a comprehensive theoretical investigation of the catalytic reaction mechanisms of propene epoxidation on gold nanoclusters using density functional theory （DFT）. We have shown that water acts as a catalytic promoter for propene epoxidation on gold catalysts. Even without reducible supports, hydroperoxyl （OOH） and hydroxyl （OH） radicals are readily formed on small-size gold clusters from co-adsorbed H20 and 02, with energy barriers as low as 4-6 kcal/mol （1 cal = 4.186 J）. Propene epoxidation occurs easily through reactions between C3H6 and the weakened O-O bond of the OOH radicals on the surfaces of gold clusters.展开更多
Au-Ag bimetallic nanoparticle‐supported microporous titanium silicalite‐1catalysts were prepared via a hydrothermal‐immersion method,and their structures were examined.These materials serve as efficient catalysts f...Au-Ag bimetallic nanoparticle‐supported microporous titanium silicalite‐1catalysts were prepared via a hydrothermal‐immersion method,and their structures were examined.These materials serve as efficient catalysts for the photosynthesis of propylene oxide via the epoxidation of propene.The Au/Ag mass ratio and reaction temperature were demonstrated to have significant effects on the catalytic activity and selectivity of propylene oxide.The optimal formation rate(68.3μmol/g·h)and selectivity(52.3%)toward propylene oxide were achieved with an Au:Ag mass ratio of4:1.Notably,the strong synergistic effect between Au and Ag resulted in superior photocatalysis of the bimetallic systems compared with those of the individual systems.A probable reaction mechanism was proposed based on the theoretical and experimental results.展开更多
基金supported by the Natural Science Foundation of China(21978325,21776312,22078364)Key research and development plan of Shandong Province(2019RKE28003,2018GGX107005)Fundamental Research Funds for the Central Universities(18CX02014A).
文摘Engineering unique electronic structure of catalyst to boost catalytic performance is of prime scientific and industrial importance.Herein,the identification of intrinsic electronic sensitivity for direct propene epoxidation was first achieved over highly stable Au/wormhole-like TS-1 catalyst.Results show that the electron transfer of Au species can be regulated by manipulating the dynamic evolutions and contents of Au valence states,thus resulting in different catalytic performance in 100 h time-on-stream.By DFT calculations,kinetic analysis and multicharacterizations,it is found that the Au^(0) species with higher electronic population can easily transfer more electrons to activate surface O_(2) compared with Au^(1+) and Au^(3+) species.Moreover,there is a positive correlation between Au^(0) content and activity.Based on this correlation,a facile strategy is further proposed to boost Au^(0) percentage,resulting in the reported highest PO formation rate without adding promoters.This work harbors tremendous guiding significance to the design of highly efficient Au/Ti-containing catalyst for propene epoxidation with H_(2) and O_(2).
基金supported by the Natural Science Foundation of China(21978325,21776312,22078364)Postgraduate Innovation Engineering(YCX2020044).
文摘The advocacy of green chemical industry has led to the development of highly efficient catalysts for direct gas-phase propene epoxidation with green,sustainable and simple essence.The S-1/TS-1@dendritic-SiO_(2) material with three-layer core–shell structure was developed and used as the support for Au catalysts,which showed simultaneously fantastic PO formation rate,PO selectivity and stability(over 100 h)for propene epoxidation with H_(2) and O_(2).It is found that silicalite-1(S-1)core and the middle thin layer of TS-1 offer great mass transfer ability,which could be responsible for the excellent stability.The designed dendritic SiO_(2) shell covers part of the acid sites on the external surface of TS-1,inhibiting the side reactions and improving the PO selectivity.Furthermore,three kinds of SiO_(2) shell morphologies(i.e.,dendritic,net,mesoporous shell)were designed,and relationship between shell morphology and catalytic performance was elucidated.The results in this paper harbour tremendous guiding significance for the design of highly efficient epoxidation catalysts.
基金supported by the National Natural Science Foundation of China-Outstanding Youth foundation(No.22322814)National Natural Science Foundation of China(No.22108307,No.22108305)+1 种基金the National Natural Foundation of Shandong Province(ZR2021QB076,ZR2020YQ17,ZR2020KB006,ZR2023YQ009 and ZR2022MB015)the Fundamental Research Funds for the Central Universities(23CX04029 A).
文摘Propylene oxide plays a pivotal role as an organic synthesis intermediate,boasting extensive downstream applications and promising market prospects.Propene epoxidation via molecular oxygen has garnered considerable attention due to its cost-effectiveness,environmental friendliness,ease of operation,and straightforward product separation.This paper provides an in-depth exploration of recent advance-ments,ranging from nanoparticle to Single-atom catalysts(SACs),in the context of propene epoxidation using molecular oxygen.Conventional nanoparticle catalysts,including those based on Ag,Cu,and other metals,are examined with regard to their contributions to support effects,electron effects,or crystal-plane effects within the mechanistic investigation.Furthermore,emerging SACs(specifically Mo,Cu,and Co)are discussed in terms of synthesis strategies,characterization methods,and mechanism studies.This comprehensive review sheds new light on design strategies,relevant characterizations,and thorough mechanism investigations aimed at fostering the development of efficient catalysts,thereby expediting progress in the industrial implementation of propene epoxidation.
基金financially supported by the National Natural Science Foundation of China(22578518,22278452 and 22378437).
文摘The direct epoxidation of propylene using H_(2) and O_(2) has emerged as a promising alternative to conventional industrial processes,offering superior atom economy,environmental compatibility,and process economics.This work demonstrates a facile design strategy to enhance Au-Ti synergy in Au/TS-1 catalysts through precise control of TPAOH/Si ratios during zeolite synthesis.Systematic reduction of TS-1 crystallite dimensions to 220 nm was achieved through TPAOH/Si ratio optimization,simultaneously producing micro-mesoporous hierarchical architectures while preserving crystallinity.The engineered Au/TS-1 catalyst prepared via a deposition-precipitation method exhibited exceptional propylene oxide selectivity(~95%)with stable activity,which is attributed to optimized electronic coupling between Au nanoparticles and framework Ti species.Spectroscopic analyses(XPS/UV-vis)revealed strengthened Au-Ti electronic interactions through positive binding energy shifts(Au 4f_(7/2):+0.4 eV;Ti 2p_(1/2):+0.9 eV),correlating with enhanced propylene activation.The catalytic efficiency was further governed by synergistic effects between accessible Ti-surrounded Au sites and surface silanol density.In situ FT-IR kinetic analysis identified two distinct reaction phases:initial rate-limiting propene chemisorption(0-20 min)followed by steady-state operation(25-55 min),with acetone and propanal identified as primary byproducts.This mechanistic understanding of structure-activity relationships advances fundamental principles for designing high-performance epoxidation catalysts while accelerating industrial implementation of sustainable propylene oxide production routes.
文摘We report a comprehensive theoretical investigation of the catalytic reaction mechanisms of propene epoxidation on gold nanoclusters using density functional theory （DFT）. We have shown that water acts as a catalytic promoter for propene epoxidation on gold catalysts. Even without reducible supports, hydroperoxyl （OOH） and hydroxyl （OH） radicals are readily formed on small-size gold clusters from co-adsorbed H20 and 02, with energy barriers as low as 4-6 kcal/mol （1 cal = 4.186 J）. Propene epoxidation occurs easily through reactions between C3H6 and the weakened O-O bond of the OOH radicals on the surfaces of gold clusters.
基金supported by the National Natural Science Foundation of China(21576050)the Natural Science Foundation of Jiangsu Province(BK20150604)~~
文摘Au-Ag bimetallic nanoparticle‐supported microporous titanium silicalite‐1catalysts were prepared via a hydrothermal‐immersion method,and their structures were examined.These materials serve as efficient catalysts for the photosynthesis of propylene oxide via the epoxidation of propene.The Au/Ag mass ratio and reaction temperature were demonstrated to have significant effects on the catalytic activity and selectivity of propylene oxide.The optimal formation rate(68.3μmol/g·h)and selectivity(52.3%)toward propylene oxide were achieved with an Au:Ag mass ratio of4:1.Notably,the strong synergistic effect between Au and Ag resulted in superior photocatalysis of the bimetallic systems compared with those of the individual systems.A probable reaction mechanism was proposed based on the theoretical and experimental results.
