Regeneration of zeolite membranes deactivated by condensable molecules

Abstract

A zeolite membrane is a microporous film on a porous substrate that can discriminate molecules in the gas and liquid phases through its pores. Although zeolite pores play a critical role in achieving a high separation performance, they tend to be clogged by condensable molecules during the separation process, resulting in a significant drop in the separation performance. In this study, the thermal regeneration of zeolite membranes deactivated by condensable molecules was investigated to achieve their reusability without significant changes in the separation performance. Silicoaluminophosphate (SAPO-34) and pentasil (MFI) membranes were prepared, and condensable vapors, including water, n-butanol, n-methyl-2-pyrrolidone, and thermally degenerated organic vapors were chosen as the foulants to block the pores of the zeolite membranes. The optimized regeneration temperature differed according to the type of foulant and zeolite framework. Overall, the optimized thermal desorption temperature of every foulant was lower for the MFI membrane because of its larger pores and more hydrophobic surfaces compared to those of the SAPO-34 membrane. For the membranes deactivated by thermally degenerated organic vapors, the pores of the zeolite membranes were opened based on organic solvent treatment followed by thermal desorption. In addition, the MFI membrane was more sensitive to heat than the SAPO-34 membrane; therefore, slight changes in the membrane selectivity were observed depending on the thermal regeneration protocols. This study demonstrated that deactivated zeolite membranes can be regenerated, and excess heat exposure during thermal regeneration can decrease gas selectivity through the creation of nonzeolitic pores. © 2022 Elsevier Ltd