A New Method to Improve the Performance of Hydrogen Selective Silica Membranes

High-performance, molecular sieve membranes are sought by DOE to separate hydrogen from other gases (mainly carbon diode) in coal gasification processes. However, because of defects, the selectivity of crystalline, silicate-based, molecular sieve membranes can be compromised. This project will develop technology to fix defects in these membranes by reducing pore size and improving gas selectivity. This solution will be accomplished through the use of a low-temperature conformal-deposition process for depositing silicate films inside the defective pores. By using a special catalyst, the deposition will occur at temperatures as low as 60oC and will be self-limited. In Phase I, the low-temperature conformal-deposition process will be developed and then used to reduce pore size in a crystalline silicate membrane. Then, the gas selectivity between hydrogen and carbon dioxide will be measured and compared to the performance of untreated membranes. Lastly, the long-term stability of the processed membrane will be determined. Commercial Applications and Other Benefits as described by the awardee: The high-flux, high-selectivity, molecular sieve membranes should find use in coal gasification processes to separate hydrogen from carbon dioxide. The technology also should be applicable to fixing defects and adjusting pore sizes in other types of inorganic membranes, in order to improve their gas separation performance.