Palladium-based membranes preparation techniques

Abstract In this chapter, recent progress on palladium (Pd)-based membrane reactors (MRs) is outUned concentrating, in particular, on the production of pure hydrogen. Aspects of many reactions, as well as analysis of both the Pd-based and the amorphous membranes under study, and the governing equations are presented. Some critical aspects of non-Pd-based membranes are also discussed. All the preparation techniques for pure, alloyed, amorphous, non-Pd-based membranes used in MRs are briefly summarized and compared. Moreover, some problems related to the effect of contamination of the Pd-based membranes on the H2 flux are discussed. 

Itoh et al. (2005) prepared a thin and firmly deposited Pd membrane applicable to surface catalysis. The technique and equipment developed in this study is based on CVD under a forced flow, where due to a pressure difference applied between the outside and the inside of the support tube the chemical vapours enter the porous layer of the support where they decompose. (CH3COO)2Pd was used as a Pd source. The tubular support made from a-alumina powder was porous and have an average pore diameter of 0.15 mm. The forced flow CVD was carried out by heating according to a temperature program under regulated vacuum pressure. The palladium membrane thus obtained was as thin as 2-4 pm and had a Hj/Nj selectivity >5000. 

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