Preparation Of Pentsail Zeolite And Its Application In Alkylation Of Benzene With Ethnol

Pentasil molecular sieves mainly include ZSM-5 and ZSM-11 molecular sieves,which are widely used in organic chemical industry,petrochemical industry and pollution control.The results show that pentsail molecular sieve has good properties of high temperature resistance,acid and alkali resistance,strong acidity and regular pore channels.As a result,pentsail zeolites have been widely used in alkylation because of their excellent catalytic performance.The traditional pentasil molecular sieves are mainly microporous molecular sieves.The pore size distribution is relatively single,and the pore size is close to the diameter of benzene molecule.As a result,it is difficult for the products to be transported out of the molecular sieves in time after the reaction of catalytic raw materials is completed,resulting in accumulation in the molecular sieves.Now,the catalytic alkylation reaction mainly adopts the high temperature and low pressure method,so the products inside the molecular sieve are easy to coking after a long time of high temperature treatment,thus covering the acid active sites of the molecular sieve,deactivating the molecular sieve and reducing the service life of the molecular sieve.Traditional ZSM-5 and ZSM-11 molecular sieves are microporous molecular sieves,which have the problems of single pore size and easy coking and deactivation.The pore structures of the two zeolites are not exactly the same,so we used different modification methods to improve the catalytic performance and stability of the two zeolites for the alkylation of benzene with ethanol.In order to adjust the pore size of ZSM-5 molecular sieves,we use the addition of structural auxiliary cationic hydroxyethyl cellulose(JR-400).After the addition of cationic hydroxyethyl cellulose,the particle size bond of ZSM-5 molecular sieves is about 50 nm.There are not only obvious mesoporous cavities in zeolite,but also obvious intergranular pores between zeolite particles.These two obvious changes can make the products transfer out of zeolite as soon as possible.In the evaluation of alkylation reaction,the catalytic stability of zeolite was extended from 28 h to 216 h,and the conversion of alkylation reaction was increased from 52% to 64%.For ZSM-11 molecular sieves,we mainly adopt the way of doping graphene(go)to adjust its structure.After doping with go,the morphology of zeolites changed greatly,and the particle size of zeolites decreased to about 20 nm.After doping graphene,the conversion ability of ZSM-11 molecular sieve for raw materials and the shape selective catalytic ability for the desired products have also been greatly improved.After doping with graphene,the conversion of ZSM-11 molecular sieve for alkylation increased to69%,and the selectivity for ethylbenzene increased to 56%.After 15 days,ZSM-11 molecular sieve was modified by graphene peroxide to catalyze the alkylation of benzene with ethanol,the conversion was still 55%.