An Hetero-Epitaxially Grown Zeolite Membrane

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).