To solve the problem of low selectivity of cresol for phenol alkylation catalyzed by ZSM-5 zeolite,a series of modified ZSM-5 catalysts was obtained by modifying the ZSM-5 zeolite prepared by the equal-volume impregnation method with silicon,phosphorus and magnesium.The ZSM-5 zeolite before and after modification was characterized by XRD,Py-IR and BET methods.The catalytic performance of modified ZSM-5 zeolites for phenol alkylation was investigated in a fixed bed reactor.The results show that the specific surface area and total acid amount of P-loaded 15P-ZSM-5 zeolite with a mass fraction of 15％are decreased from 395 m2/g and 406 μmol/g to 309 m2/g and 128 μmol/g,respectively,and the external surface acid amount is decreased from 18 μmol/g to 3 μmol/g.The phenol alkylation reaction was catalyzed at the mass space velocity of 12 h-1,reaction temperature of 420 ℃ and reaction pressure of 1.5 MPa.Under the catalysis of the P-loaded 10P-ZSM-5 zeolite with a mass fraction of 10％,the conversion rate of phenol and selectivity for cresol are 52.4％and 15.4％respectively.Phosphorous modification can adjust the surface acid amount of ZSM-5 zeolite by using phosphate anions to cover the acid sites on the external surface of ZSM-5 zeolite,and improve the selectivity for cresol.Compared with other modified zeolites,the phosphorous modified zeolite has the best performance in phenol alkylation reaction.
关键词
ZSM-5分子筛/苯酚/甲醇/对甲酚/烷基化/固定床反应器/改性
Key words
ZSM-5 zeolite/phenol/methanol/p-cresol/alkylation/fixed bed reactor/modification
维普
万方数据