H-MCM-22和H-MCM-36分子筛对苯与异丙醇烷基化反应的催化性能

Catalytic Performance of H-MCM-22 and H-MCM-36 Zeolites for Alkylation of Benzene with Isopropanol

由同一前驱体合成了H-MCM-22和H-MCM-36分子筛.采用X射线衍射、N2吸附、程序升温脱附和红外光谱等方法,结合不同的表面后处理手段,研究了分子筛的结构和表面酸性.结果表明,H-MCM-22的B酸中心主要分布在内表面,H-MCM-36的B酸中心主要分布在外表面.H-MCM-36的总B酸量小于H-MCM-22,但其外表面B酸量相对较大.在苯与异丙醇的烷基化反应中,两个分子筛都表现出较为优异的催化性能.与H-MCM-22相比,H-MCM-36具有更高的反应活性和稳定性,对主产物异丙苯具有更好的选择性.结合各种表征结果表明,两个分子筛的外表面B酸中心是苯与异丙醇烷基化反应的主要活性中心.

The structure and acidity of H-MCM-22 and H-MCM-36, which were synthesized from the same precursor, were investigated by X-ray diffraction, N2 adsorption, temperature-programmed desorption, and infrared spectroscopy combining different posttreatment methods. The results showed that Bronsted acid sites are mainly located on the internal surface of H-MCM-22 and mainly located on the external surface of H-MCM-36. Both H-MCM-22 and H-MCM-36 zeolites are active for the alkylation of benzene with isopropanol. Compared with H-MCM-22, H-MCM-36 showed higher activity and selectivity for cumene, which is due to the fact that H-MCM-36 possesses more accessible Bronsted acid sites than H-MCM-22. In other words, the Bronsted acid sites located on the external surface of zeolites are the main active centers for the alkylation of benzene with isopropanol.