The zeolites of MCM-22, MCM-49 and MCM-56 which have MWW layered structure were synthesised by dynamic hydrothermal method. The structure, pore volume distribution and acid property of these samples were characterized by means of XRD, BET, NH
3-TPD and Pyridine-IR.The catalytic performance of these zeolites were experimentally compared with the model reaction of alkylation of benzene with propylene, the relationship between product distribution, pore structure and acid property was also investigated. The results show that MCM-49 have the most amount of B acid sites, whereas the L acid sites predominates in MCM-56 zeolite. These three zeolites all have good catalytic performance and similar product distribution and the conversions of propylene over them are more than 99.9%.The selectivity of isopropyl benzene(IPB) over MCM-49 zeolite is the highest. However, the amount of n-propyl benzene is the highest too. Deep alkylation of IPB tend to take place on the external surface due to the small steric effect of MCM-56, so the amount of diisopropyl benzene and tri- isopropyl benzene in MCM-56 are higher than the other two zeolites.
2008, 21 (1):
4-7.
