ULTRAMICROPOROUS MEMBRANES FOR HYDROGEN SEPARATION M.C. DUKE * , J.C. DINIZ DA COSTA * , G.Q. (MAX) LU * , M. PETCH ** AND P. GRAY ** * The Nanomaterials Centre, Division of Chemical Engineering, The University of Queensland Brisbane, Queensland, 4072, Australia. ** Johnson Matthey Technology Centre, Sonning Common Reading RG4 9NH, United Kingdom. SUMMARY: Fuel cell systems offer excellent efficiencies when compared to internal combustion engines, which result in reduced fuel consumption and greenhouse gas emissions. One of the areas requiring research for the success of fuel cell technology is the H 2 fuel purification to reduce CO, which is a poison to fuel cells. Molecular sieve silica (MSS) membranes have a potential application in this area. In this work showed activated transport, a characteristic of ultramicroporous (dp<5Å) materials in which the permeation increased with temperature. H 2 permeance resulted in 1.2 x 10 -8 mol.m -2 .s -1 .Pa -1 and a H 2 /CO permselectivity of 33 (200 o C, 2 bar P). Observations made during surface preparation showed that the permeance was not hindered by the intermediate layers, and that only the top (selective) layer played a significant role in reducing gas permeance. The pressure difference across the membrane showed that the permeance was pressure independent, except at pressures below 2 bar, which resulted in a higher permeance. High quality membranes purified a mixed gas containing 42% H 2 by over two fold with the remainder being made up of N 2 , CO 2 and CO. These are encouraging results for applying MSS membranes to environmentally promising fuel cell systems. 1. INTRODUCTION Highly populated urban areas are exposed to pollution arising from transport systems. Today, modern internal combustion engine (ICE) vehicles equipped with catalytic converters essentially eliminate toxic emissions such as CO and NO x , however CO 2 is still a by-product. It is now commonly accepted that CO 2 is a greenhouse gas and must be reduced to prevent global warming. Fuel cell systems incorporating high quality membranes can offer a solution to this. Other major factors driving membrane technology in fuel cell systems are regulations, energy efficiency and cost effectiveness. Fuel cells emit less carbon dioxide and nitrogen oxides per kilowatt of power generated (ECW, 2000). As processes become more efficient by employing membranes, they greatly reduce energy consumption leading to lower usage of fossil fuels and lower emission of greenhouse gases. Low temperature fuel cells with membranes for H 2 removal from CO have electrical efficiency of 42% (Rastler et al., 1996), which is much higher than the conventional combustion engines efficiency of up to 33%. Proceedings EERE 2002, Environmental Engineering Research Event Blackheath, NSW, 3-6 th December 2002