Effect of NaOH Treatment on Catalytic Performance of ZSM-5 in Cyclohexene Hydration

ZSM-5 zeolite prepared by a hydrothermal method with the addition of seeds was treated with different concentrations of NaOH. The obtained samples were characterized by XRD, N₂ adsorption, NH₃-TPD, FT-IR, SEM, and studied in the catalytic performance of the hydration of cyclohexene to cyclohexanol. The characterization results showed that with the increase of NaOH concentration, the crystallinity of the treated samples decreased monotonously, and the acid sites of ZSM-5 zeolites first increased and then decreased, while more mesopores formed inside the ZSM-5 zeolites. The experimental results of catalytic performance showed that cyclohexene conversion can be improved through introducing the mesopores and enhancing the acidity of ZSM-5 with the NaOH treatment at a low concentration. The highest cyclohexene conversion of 12.8% was obtained when the concentrations of NaOH solution were in the range of 0.2–0.6 mol/L. The selectivity of cyclohexanol on all samples was higher than 99.6%.