Preparation And Catalytic Performance Of Metal Organic Framework(UIO-67,UIO-66)Supported Au/Pd Nanoparticles

As a porous material with high specific surface area and porosity,metal-organic framework(MOFs)is a good catalyst carrier material.In this paper,zirconium-based metal organic framework UIO-67 and UIO-66 were used as carrier material,and a variety of supported M@MOF composite catalysts were prepared by impregnation reduction method or controlled particle encapsulation method,and the catalytic activity was investigated.The framework structure of the three supported Au@UIO-67 catalysts(Au@UIO-67-H2,Au@UIO-67-NaBH4,Au@UIO-67-oleylamine)prepared by impregnation reduction method was still remained intact,while the carrier UIO-67 turned into ZrO2 after high temperature CO2 catalytic hydrogenation.The active components of the three catalysts are all Au0,Au particles on the surface of Au@UIO-67-oleylamine and Au@UIO-67-NaBH4 had different degrees of agglomeration and sintering,and the catalytic efficiency is relatively low.However,Au particals on Au@UIO-67-H2 had smaller size and were inserted into the UIO-67 surface pores,and did not sinter at high temperature,which resulted in higher catalytic efficiency.Au@UIO-66 and Pd@UIO-66 catalysts were prepared by impregnation reduction method and the properties for catalytic reduction of p-nitrophenol under different conditions were studied.The results showed that nano-gold and nano-palladium were highly dispersed on the supporter UIO-66 and nano-palladium had two states-nanoparticles and nanowires.The catalytic performance of two catalysts for the catalytic reduction of p-nitrophenol under different conditions was studied,both catalysts had high catalytic activity.When 10 mg catalyst was used in 100 mL p-nitrophenol water solution(1.6×10-4 mmol/mL),the conversion can reach more than 95%within 5 min.The core-shell Au@UIO-67 and Au@Pd@UIO-67 composites were prepared by controlled particle encapsulation method.The size of AuNPs were increased due to the dissolution and recrystallization of AuNPs,while Au@Pd NPs avoided the dissolution and recrystallization due to Pd coating on the surface of Au NP.The core-shell structure with size of 70-110 nm can be obtained by changing the reaction conditions.