Enhanced catalytic properties of palladium nanoparticles deposited on a silanized ceramic membrane support with a flow-through method

A flow-through method was developed for the deposition of palladium nanoparticles on a ceramic membrane support modified with aminofunctional silane to fabricate a Pd-loaded ceramic membrane support. The as-fabricated Pd-loaded ceramic membrane support was extensively characterized by energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma (ICP) emission spectroscopy, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and temperature-programmed reduction (TPR), and its catalytic properties were evaluated in the reduction of p-nitrophenol to p-aminophenol with sodium borohydride. For comparison, the palladium nanoparticles were also deposited on a silanized ceramic membrane support by a traditional impregnation method. Superior p-nitrophenol conversion and catalytic stability are observed on the Pd-loaded ceramic membrane support prepared by the flow-through method. In the flow-through method, the synthesis solution is forced to flow through the membrane pores, thus the palladium nanoparticles can be deposited both on the membrane surface and in the membrane pores, resulting in an increased loading amount of palladium nanoparticles and an enhanced p-nitrophenol conversion. The superior catalytic stability is related to the preparation process: the palladium nanoparticles deposited on the membrane support will be scoured by the synthesis solution, some palladium nanoparticles having poor interaction with the membrane support may fall off during the preparation stage, and the remaining palladium nanoparticles have stronger interactions with the membrane support and do not easily fall off during the continuous reaction cycles, leading to better catalytic stability.