Preparation and evaluation of palladium/kieselguhr composites for hydrogen isotope separation

Abstract

The palladium/kieselguhr composites (Pd/K) were prepared by the PdCl₂ dipping-reducing method. The effects of the preparation conditions on the Pd/K were studied, such as the heat treatment, dipping time, palladium concentration in solution and number of loading cycles. The pore structure and palladium content of the Pd/K were measured by the Brunauer–Emmett–Teller method and an inductively coupled plasma mass spectrometry. The appearance and palladium element distribution were measured by a scanning electron microscope. It is found that the palladium element is more densely distributed in the irregular and porous parts of the kieselguhr particles, so the kieselguhr is superior to Al₂O₃ as the carrier material. The heat treatment can improve the pore permeability and increase the palladium content for the Pd/K. Increasing the dipping time, palladium concentration in solution and number of loading cycles is beneficial to increase the palladium content of the Pd/K, but more loading cycles may lead to the pore collapse, which obstructs the interaction with the hydrogen isotope gases. A kind of Pd/K was prepared under a set of optimized conditions and was packed in a separation column. This Pd/K was proved to be of high performance and durable by some hydrogen–deuterium separation experiments.