Study On Selective Hydrogenation Of Avermectin To Ivermectin Over Supported Metal Catalyst

prepared by the hydrogenation of avermectin. Wilkinson catalyst RhCl(PPh3)3 is an usual choice to selective hydrogenation of Avermectin to Ivermectin. Heterogeneous catalysts have exhibited nice catalytic performance on many selective hydrogenations in liquid phase, but there is no report on selective hydrogenation of Avermectin to Ivermectin. Ir/γ-Al₂O₃ was prepared by impregnatingγ-Al₂O₃ with an aqueous solution of or microemulsion solution of H2IrCl6. The catalyst was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscope (TEM), and its catalytic performance for the selective hydrogenation of avermectin to ivermectin was investigated. The effects of reduction methods on the catalytic and selectivity were studied. It was found that Ir/γ-Al₂O₃ modified with PVP exhibited the higher activity and selectivity. The addition of PVP to Ir/γ-Al₂O₃ not only improved the catalytic activity, but also increase the catalytic selectivity. The conversion of avermectin and the selectivity for ivermectin increased from 55.3% and 65.3% to 82.0% and 80.8%. Furthermore, it was found thatγ-Al₂O₃ was a better support than AC,α-Al₂O₃ and TiO₂ in this system, the order of acitvity supported metal catalyst is Ir/γ-Al₂O₃ > Pd/γ-Al₂O₃ > Ru /γ-Al₂O₃> Pt /γ-Al₂O₃.