Fabrication of ceramic membrane supported palladium catalyst and its catalytic performance in liquid-phase hydrogenation reaction

Immobilization of metal nanoparticles (MNPs) on membranes to fabricate membrane catalysts is a promising approach for the catalysis. The membrane surface property plays a key role for the loading of MNPs. In this study, dopamine was adopted to functionalize the ceramic membrane and then Pd NPs were loaded on the modified membrane to fabricate a membrane catalyst. The microstructure of as-synthesized membrane catalyst was investigated and its catalytic properties were tested in the p-nitrophenol reduction to p-aminophenol with sodium borohydride. Furthermore, the reaction kinetics of p-nitrophenol reduction over the membrane catalyst was studied. Higher catalytic activity and stability were observed for the Pd NPs deposited on the polydopamine-functionalized membrane as compared to the membrane without modification. The reason proposed for the higher catalytic activity was the higher loading amount of Pd NPs. The Pd NPs were loaded onto the functionalized ceramic membrane by chemical bonds through the bridging function of polydopamine; thus, it was not easy for the Pd NPs to detach from the membrane, and a superior catalytic stability could be obtained. A lower activation energy was found for the as-synthesized membrane catalyst, which should be related to the small Pd particle size and the flow-through operation model. These findings would provide novel ideas for the synthesis of membrane catalysts with outstanding catalytic properties.