SBIR Phase I: A Self-Limited Method to Improve the Gas Selectivity of Zeolite Microporous Membranes

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This Small Business Innovation Research Phase I project proposes a self-limited method to repair defects in c-oriented zeolite molecular sieve membranes. In this project, we will use a self-limited catalyzed low temperature method to grow silicate coatings inside the defective membrane regions. The use of catalysts will enable the deposition to proceed at temperatures ~ 60C and only occur in pores with a diameter of 7 angstroms. After the deposition, the membrane will be heated up to ~400C to densify the silicate deposit by promoting cross-linking, which further reduces the pore size in the defective grain boundary regions. This process will plug the defective grain boundaries in a self-limited manner down to a pore size of ~ 5-6 angstroms, without affecting the main membrane matrix and greatly improve the gas selectivity of the molecular sieve membranes. If successful, the direct benefit from this research is much enhanced gas selectivity for separating p-xylene from o-xylene isomers. Xylene is one of the top 30 chemicals produced in the United States in terms of volume. Currently, it has a yearly production volume of 22 Million metric tons. Xylene separation with MFI membranes offers an economic and continuous alternative for p-xylene production.