Effects of different silica intermediate layers for hydrogen diffusion enhancement of palladium membranes applied to porous stainless steel support

Sci Rep. 2020 Mar 20;10(1):5148. doi: 10.1038/s41598-020-62054-3.

Abstract

Porous stainless steel (SUS) supports were modified with double intermediate layers, silicalite-1 and γ-alumina, to enhance the hydrogen diffusion of a thin palladium membrane. One of layers, silicalite-1, was prepared using the hydrothermal synthetic method on porous SUS supports. The differences in expansion/contraction behaviors caused by different thermal coefficients of expansion between silicalite-1 and the SUS resulted in a lowering of the durability of the membrane. Intermediates layers of mesoporous MCM-48 powders or commercial spherical non-porous silica particles were then applied to porous SUS supports via aspiration, γ-alumina was introduced by dip-coating, and the Pd membrane was subjected to electro-less plating. H2 permeance of the Pd membrane (membrane thickness: 11 μm) containing spherical silica particles was around 10 × 10-6 mol·m-2·s-1·Pa-1 at 600 °C, which was higher than that of the Pd membrane (membrane thickness: 7 μm) containing MCM-48. The durability of the Pd membrane containing spherical silica particles was higher than that of the version containing MCM-48 powders. These results suggest that commercial spherical non-porous silica particles will uniformly occupy the pores of the SUS tubes and enhance the H2 permeance and durability of the Pd membrane.