不同硅铝比两亲性HZSM-5沸石的制备和表征

Preparation and Characterization of Amphiphilic HZSM-5 Zeolite with Various Si/Al Ratios

采用三甲基氯硅烷并通过控制水的添加量对硅铝比分别为25,42和101的HZSM-5沸石进行外表面修饰,制得三种两亲性沸石样品.水的添加量对沸石催化剂的两亲性有显著影响.红外光谱和低温氮吸附等测试结果表明,两亲性沸石样品具有与各自母体沸石相似的酸性及略小的比表面积.在环己烯水合及乙酸异戊酯水解的相界面反应中,两亲性沸石分布于水-油两相界面,并表现出明显高于各自母体沸石的催化活性.硅铝比为42的两亲性HZSM-5样品表现出最佳的相界面催化性能.相对于环己烯水合反应,两亲性HZSM-5沸石更适用于乙酸异戊酯水解的相界面催化反应.

Amphiphilic HZSM-5 zeolite particles with Si/Al ratios of 25, 42 and 101 were prepared by partial modification of the external surfaces of the HZSM-5 zeolite with trimethylchlorosilane. The amount of water added during the preparation influences the amphiphilic properties of the zeolites. The results of IR spectroscopy and N2 adsorption indicate that these amphiphilic zeolite samples have the similar acidity and a little smaller surface area compared to their parent zeolites. In the phase-boundary reactions of cyclohexene hydration and isoamyl acetate hydrolysis, these amphiphilic zeolite particles are oriented at the aqueous-organic phase boundary and exhibit catalytic activity obviously superior to the parent zeolites. The amphiphilic HZSM-5 with a Si/A1 ratio of 42 shows the best catalytic performance. Furthermore, the amphiphilic HZSM-5 is a more effective phaseboundary catalyst for the isoamyl acetate hydrolysis than for the cyclohexene hydration.