Microparticle HZSM-5 zeolite as highly active catalyst for the hydration of cyclohexene to cyclohexanol

摘要

Microparticle HZSM-5 zeolite (MPZ) has been prepared without employing any organic templates, and used as a catalyst for the hydration of cyclohexene to synthesize cyclohexanol. MPZ exhibits better catalytic performance and superior settlement separation property than those of commercial HZSM-5 prepared by the traditional method using an organic template. The stability of MPZ has been investigated for a 1200-h test, and the regenerated performance of MPZ has also been investigated. The results show that although MPZ was reused for five recycles, the high cyclohexene conversion of 9.6 % and the high cyclohexanol selectivity of 96.8 % are still attained after the fifth regeneration. FT-IR, XRD and N-2 adsorption-desorption characterizations show that coke deposit on the surface and in the channels of MPZ is the main reason for the deactivation. ICP-AES, SEM-EDS and NH3-TPD characterizations indicate that hydrothermal dealumination reduces the strong acidity and accelerates the catalyst deactivation. The spent catalyst by regeneration with H2O2 could be recovered to its initial high catalytic activity, due to the restored appropriate channels and exposed active sites.