Preparation Of Silver Base Hierarchically Porous 4A-Zeolite Composite Catalyst And Their Catalytic Performance For Styrene Epoxidation

Hierarchically porous zeolites,with the advantages of a collection of microporous molecular sieves,mesoporous molecular sieves and macroporous molecular sieves,are novel nanomaterial.Hierarchically porous zeolites overcome the disadvantages that narrow pores of traditional microporous zeolite are not conducive to the diffusion of macromolecules and mesoporous zeolite and macroporous zeolite have poor stability,which have greatly increased the potential application value of hierarchically porous zeolites.It has attracted more and more researchers’attention and research.In this paper,the formation process and catalytic performance of hierarchically porous4A-zeolite（P-4A-zeolite）and silver-basedhierarchicallyporous 4A-zeolite（Ag/P-4A-zeolite）that it was prepared through novel methods of chemical complexation,electrospinning,hydrothermal synthesis,high temperature heat treatment and supercritical loading techniques,were investigated.The specific research content is as follows:1.The Ag/4A-zeolite was successfully prepared by a one-step hydrothermal method,and P-4A-zeolite composite nanomaterials were successfully prepared through liquid bromine impregnation treatment and Na₂S₂O₃ complexation.The FESEM,TEM,UV-vis and XRD characterizations indicate the structure and morphology of all samples.2.The CNFs were prepared by electrospinning that were use as hard template agent.After CNFs are treated,they are added to silica-alumina sol to perform hydrothermal process.The C-4A-zeolite was prepared.The P-4A-zeolite composite nanomaterial was prepared by high temperature heat treatment in air atmosphere.Then,the Ag/P-4A-zeolite composite catalysts were prepared using supercritical loading technology,and their catalytic activity was explored.The morphological characteristics,state characteristics and attribute characteristics of these samples were performed by FESEM,TEM,TG,BET（BJH）,XRD,XPS,and UV-vis.The catalytic experiment proves when the reaction solvent was acetonitrile and the oxygen source was TBHP.The conversion rate of styrene reaction can reach 86.06%and the selectivity for epoxy styrene can reach 86.41%at 82°C for10h.3.The Ag/CNFs as the hard template agent were prepared though changing the electrospinning conditions based on the research background of the second part.The Ag/P-4A-zeolite composite catalyst was successfully prepared only by the hydrothermal synthesis and high temperature heat treatment process.And the catalytic activity was verified.The morphology and structural characteristics of Ag/P-4A-zeolite composite catalysts were characterized by FESEM,TEM,TG,UV-vis,XRD,XPS,and BET（BJH）,and so on.When the reaction solvent was acetonitrile and the oxygen source was TBHP,the conversion rate of styrene reaction can reach 90.33%and the selectivity for epoxy styrene was 87.10%at 82°C for 10 hours.The Ag/P-4A-zeolite has a higher catalytic activity than previously reported thorough comparison.