Amphiphilic HZSM-5 for Cyclopentene Hydration at the Liquid–Liquid Interface in Pickering Emulsion

Zeolite is considered an ideal catalyst for olefin hydration due to its high specific surface area and abundant acid sites. However, the immiscibility of the water–oil two phases in olefin hydration limits mass transfer, and the side reaction of etherification occurs acutely, resulting in a low yield of alcohol. Thus, water–oil amphiphilic HZSM-5 was prepared by sulfonating silanized zeolite. The successful introduction of organic and sulfonic acid groups is demonstrated by FT-IR, TG, and water contact angles. Amphiphilic HZSM-5 can stabilize the Pickering emulsion and catalyze cyclopentene hydration at the phase interface. In addition, NH3-TPD and Py-IR show that the amount of strong Bro̷nsted acid sites of zeolites increases significantly after sulfonation. This facilitates the rate-determining step of cyclopentene activation by H+ to form carbocation. Moreover, the nucleophilic side reactions are inhibited by a high concentration of H+. Finally, under the optimized reaction condition, the conversion of cyclopentene can achieve 5.066% with a selectivity of 85.37% to cyclopentanol, which almost reaches the reaction equilibrium.