Abstract: Zeolites of ZSM-5, ZSM-11 and hierarchical pore structure ZSM-11 were synthesized via steam-crystallization and characterized by XRD, SEM, NH3-TPD, BET and TG techniques. The results show that synthesized ZSM-5 and ZSM-11 possesses similar BET surface area, micropore volume, crystal size, and acidity. Mesopores were introduced in hierarchical ZSM-11, and the micropores of the ZSM-11 sieve were retained. In the alkylation of benzene with methanol, ZSM-11 showed better activity and stability compared with ZSM-5, owing to the higher diffusion rates of the C7, C8 and other aromatics in ZSM-11 sieve. Hierarchical ZSM-11 performed further improvement in activity in contrast with conventional ZSM-11. At 460°C, 0.20MPa and the WSHV of 3h-1, the benzene conversion reaches 54.3%, and the total selectivity for toluene and xylene is 91.9% with xylene selectivity of 37.9%. Meanwhile, the activity of hierarchical ZSM-11 is stable after 240 h on stream, showing better stability than micropore ZSM-5 sieve.

Key words: ZSM-5, ZSM-11, benzene, methanol, alkylation