An Hetero-Epitaxially Grown Zeolite Membrane.

Abstract

The secondary growth methodology to form zeolite membranes has stringent requirements for homogeneous epitaxial intergrowth of the seed layer and limits the number of accessible high-quality zeolite membranes. Despite previous reports on hetero-epitaxial growth, high-performance zeolite membranes have yet to be reported using this approach. Here, the successful hetero-epitaxial growth of highly siliceous ZSM-58 (DDR-type zeolite) films from a SSZ-13 (CHA-type zeolite) seed layer is reported. The resulting membranes show excellent CO2 perm-selectivities, having maximum CO2 /N2 and CO2 /CH4 separation factors (SFs) as high as about 17 and 279, respectively, at 30 °C. Furthermore, the hybrid membrane maintains the CO2 perm-selectivity in the presence of water vapor (the third main component in both cases), that is, CO2 /N2 SF of about 14 and CO2 /CH4 SF of about 78, respectively, at 50 °C (a representative temperature of both CO2 -containing streams).