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

本小企业创新研究一期项目提出了一种自限修复c型分子筛膜缺陷的方法。在本项目中，我们将采用自限催化低温法在缺陷膜区域内生长硅酸盐涂层。催化剂的使用将使沉积在~ 60C的温度下进行，并且只发生在直径为7埃的孔隙中。沉积后，将膜加热至~400C，通过促进交联使硅酸沉积致密，从而进一步减小晶界缺陷区域的孔径。在不影响主膜基质的情况下，将缺陷晶界自限堵塞至~ 5 ~ 6埃的孔径，大大提高了分子筛膜的气体选择性。如果成功，该研究的直接好处是大大提高了对二甲苯和邻二甲苯异构体分离的气体选择性。二甲苯是美国产量最高的30种化学品之一。目前，它的年产量为2200万吨。用MFI膜分离二甲苯为对二甲苯的生产提供了一种经济、连续的替代方法。

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.