负载金属催化剂Ir(γ-Al2O3)对阿维菌素选择加氢反应研究

分别采用氢气、NaBH₄、醇水混合溶剂还原, PVP(聚乙烯吡咯烷酮)保护和微乳液法制备了γ-Al₂O₃负载的Ir金属催化剂, 通过XPS、XRD、TEM对催化剂的结构进行了表征, 考察了催化剂对阿维菌素选择加氢制备伊维菌素的性能, 探讨了催化剂制备方法对催化剂活性和选择性的影响. 实验结果表明, 在不同金属催化剂Ru/γ-Al₂O₃、Pd/γ-Al₂O₃、Pt/γ-Al₂O₃、Ir/γ-Al₂O₃中, Ir/γ-Al₂O₃的活性和选择性最好. 用PVP保护的Ir/γ-Al₂O₃, 其催化活性和选择性比没有PVP保护的催化剂有显著提高; 采用微乳液法制备的Ir/γ-Al₂O₃催化剂显示出最好的活性, 但反应选择性比PVP保护的催化剂差.

Study on Selective Hydrogenation of Avermectin to Ivermectin over Ir/γ-Al2O3

Catalysts Ir/γ-Al₂O₃ were prepared by impregnating γ-Al₂O₃ with an aqueous solution or microemulsion solution ofH₂IrCl₆. The catalystswere characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscope (TEM). The catalytic performance of the supportediridiumcatalysts for the selective hydrogenation of avermectin to ivermectin was investigated. Compared with active carbon (AC), α-Al₂O₃, and TiO₂, γ-Al₂O₃ is a better support in this system. Among Ir, Ru, Pd, and Pt supported on γ-Al2O3, the catalyst Ir/γ-Al₂O₃ showed the best catalytic activity and selectivity to ivermectin. Ir/γ-Al₂O₃ prepared by means of microemulsion solution showed the best catalytic activity, but the catalytic selectivity to ivermectin was lower that over Ir/γ-Al₂O₃ modified with PVP (polyvinylpyrrolidone), which exhibited excellent activity as well as good selectivity.