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
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.
