Preparation Of Mesoporous Molecular Sieve Supported Composites And Their Catalytic Performance

Compared with other microporous molecular sieves,ordered silica-based mesoporous molecular sieves have many advantages,such as larger surface area,easy adjustment of pore diameter and surface modification,and have good application prospects in adsorption,catalysis and ion exchange.Some catalytic activities of the pure ordered silica mesoporous molecular sieves such as acidity,oxidation and reduction were not observed.Therefore,In order to investigate the aspects of the catalytic application performance of ordered silica mesoporous molecular sieves,we need to introduce active material and functional modification to improve its catalytic activity.In addition,the pore size of mesoporous molecular sieves is also a factor affecting the catalytic activity for some macromolecular reactions.On the basis of these factors,this paper mainly studies the following aspects:?1?Different pore size of well-ordered hexagonal mesoporous silica structures?SBA-15?was obtained using n-hexane as a micelle expander and NH4NO3 as structure adjuvant and used as support material.A kind of-SO3 H functionalized environmentally Br?nsted acidic ionic liquids?[PSMim][HSO4]?were synthesized using to load onto different pore size SBA-15.Supported ionic liquids acid catalysts?1-IL@SBA-15?5nm,8nm,12nm??were prepared by the impregnation method and their physicochemical properties were characterized by means of FT-IR,TG-DSC,N₂ physical adsorption,XRD and TEM.The catalytic activity of the synthesized acid catalysts was investigated in the alkylation of phenol with tert-butyl alcohol.The effect of amount of IL supported,weight hour space velocity?WHSV?,reactant mole ratio,reaction temperature,pore size of SBA-15 on the conversion of phenol and selectivity to products were investigated.Compared to 1-IL@SBA-15?5nm?and 1-IL@SBA-15?12nm?,1-IL@SBA-15?8nm?shows best phenol conversion up to 85.5% at temperature as low as 80? and low alcohol to phenol molar ratio of 2:1.It is demonstrated that with the same content ionic liquid of catalysts,SBA-15?8nm?as supporter have remarkably catalytic activity and selectivity,as compared to that of SBA-15?5,12nm?as a carrier.?2?Mesoporous silica?MCM-41?with different pore diameters was prepared by using 1,3,5-trimethylbenzene as a micellar expansion agent.The functionalized acidic ionic liquid containing sulfonic acid group?[PSMim][HSO4]?was loaded onto MCM-41 with different pore diameters by impregnation method and the 1-IL @ MMC-41?2.4nm,3.6nm,4.8nm?was prepared.The physical and chemical properties were characterized by FT-IR,TG-DSC,N₂ adsorption,XRD and TEM.The effects of reaction temperature and pore size of MCM-41 on the alkylation of phenol and tert-butanol were studied.The results showed that compared to 1-IL @ MCM-41?2.4nm?and 1-IL @ MMCM-41?3.6nm?,1-IL @ MMC-41?4.8nm?exhibited the highest conversion of phenol 78.7% at temperature of 80?.It was proved that compared with the MCM-41?2.4nm,3.6nm?which was the same as the carrier with the same content of the catalyst,the MCM-41?4.8nm?had better catalytic activity and selectivity.?3?The mesoporous molecular sieve?SBA-15?was modified by the trimethylchlorosilane as functional agent and the organic-inorganic composite mesoporous matrix was made in this work.The alcohol solution of perfluorinated sulfonic acid dissolved from the waste perfluorinated sulfonic acid ion exchange membrane?PFSIEM?was loaded onto the composite mesoporous matrix by the impregnation method and their physicochemical properties were characterized by FT-IR,N₂-physisorption,XRD and TEM.The influence of several variables on the alkylation of phenol and tert-butanol,such as the reaction temperature and weight hour space velocity,reaction time,were assessed by means of a series of experiments.The results show that with the increase of the active component of the catalyst,the catalytic materials remained still good mesoporous structure.The maximum phenol conversion of 89.3% was achieved at 120? and the WHSV is 4 h-1.The methyl group was loaded on the surface of the catalyst by trimethylchlorosilane.This is beneficial to retard the deactivation of the catalyst.