Study on the One-pot Catalytic Synthesis of Cyclohexanol from Benzene ——Influence of ZnSO_4 on the Hydration of Cyclohexene Catalyzed by HZSM-5

One-pot catalytic synthesis of cyclohexanol from benzene was studied,and the influence of compounds involved in benzene selective hydrogenation on the hydration of cyclohexene was investigated.It was found that the ZnSO4 which was used as promoter for increasing cyclohexene selectivity shows great negative impact on the cyclohexene hydration.When ZnSO4 concentration in water is 0.2 mol·L-1,the cyclohexanol yield is only 1.0%.NH3-TPD,Py-IR,FT-IR and XRD were used respectively to investigate the change of HZSM-5,the catalyst for cyclohexene hydration.It could be concluded that the ZnSO4 leads to the dealuminization of HZSM-5 during reaction,which results in the decrease of Al-OH on the surface of HZSM-5.In other words,the amount of Br·nsted acid sites on HZSM-5 decreases,thereby its catalytic performance for cyclohexene hydration decreases.The substitution for ZnSO4 was explored,and it was found that the Al2(SO4)3 shows relatively weak effect on HZSM-5.When Al2(SO4)3 concentration is 0.2 mol·L-1,the cyclohexanol yield is 7.0%.Therefore Al2(SO4)3 can be used as the promoter for benzene selective hydrogenation in the one-pot synthesis of cyclohexanol from benzene.