There is a great need for robust, defect-free, highly selective molecular sieve (zeolite) thin film membranes for light gas molecule separations in hydrogen fuel production from CH₄ or H₂O sources.  In particular, we are interested in (1) separating and isolating H₂ from H₂O and CH₄, CO, CO₂, O₂, N₂ gases; (2) water management in PEMS, and (3) as a replacement for expensive Pt catalysts needed for PEMS.  Current hydrogen separation membranes are based on Pd alloys or on chemically and mechanically unstable organic polymer membranes.  The use of molecular sieves brings a stable (chemically and mechanically stable) inorganic matrix to the membrane. The crystalline frameworks have “tunable” pores that are capable of size exclusion separations. The frameworks are made of inorganic oxides (e.g., silicates, aluminosilicates, phosphates) that bring different charge and electrostatic attraction forces to the separation media.  The result is materials with high separation abilities plus inherent thermal stability over 600°C and chemical stability.  Furthermore, the pore sizes and shapes are defined crystallographically (<1Ĺ deviation) which allows for size exclusion of very similarly sized molecules.  In comparison, organic polymer membranes are successful based on diffusion separations, not size exclusion. We envision impact of positive results from this program in the near term with Hydrocarbon fuels, and long term with Biomass fuels.

Team: Tina Nenoff, Margaret Welk

Funding: DOE/H2, Fuel Cells, Infrastructure, FY04-06