摘要
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.
基金
financially supported by the National Natural Science Foundation of China(22578518,22278452 and 22378437).
