Preparation of Pd/SAPO-34/PSS composite membranes for hydrogen separation: Effect of crystallization time on the zeolite growth on PSS support

Abstract

In this study, palladium composite membranes were fabricated on porous stainless steel (PSS) supports using silicoaluminophosphate (SAPO) zeolite (SAPO-34) as a diffusion barrier and substrate modifier. The vacuum-assisted seeding and secondary growth method was used to coat the SAPO-34 zeolite layer on the PSS substrates. The morphologies and microstructures of the membranes were analyzed by AFM, XRD, BET, ICP–AES, FESEM and EDX techniques. The effect of crystallization time (24, 48 and 72h) on the morphology and quality of SAPO-34 modified supports was studied. A continuous palladium layer with a thickness of about 9μm was deposited on the SAPO-34 modified PSS support (72h crystallization time) by electroless plating (ELP) route. The hydrogen permeation tests were carried out in the feed pressures range of 2–4bar and various temperatures (623, 673 and 723K). The values of the hydrogen permeance and ideal selectivity of H2/N2 for the PSM3 membrane were achieved 7.1×10–7molm–2s–1Pa–1 and 866, respectively a feed pressure of 2bar and 723K. In addition, the PSM3 membrane showed perfect stability during 260h hydrogen permeation experiment at a feed pressure of 2bar and 623K.