Preparation of Ru-[bmim]BF4 Catalyst Using NaBH4 as Reducing Agent and Its Performance in Selective Hydrogenation of Benzene

A Ru-[bmim]BF4 catalyst was prepared in a mixture of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) and H2O using NaBH4 as a reducing agent. The Ru-[bmim]BF4 catalyst showed higher selectivity for cyclohexene than a catalyst reduced by N2H4·H2O because of the influence of boron. When Ru-[bmim]BF4 was reused, higher activity and lower selectivity were obtained because the number of Ru active sites increased through leaching of the ionic liquid. The used catalyst also contained ZnOHF formed in the reaction between F− and ZnSO4, which was an additive in the reaction. Under the influence of the ionic liquid as a template, ZnOHF grew along the (001) direction and exhibited rod-like morphology.