High-Performance Randomly Oriented Zeolite Membranes Using Brittle Seeds and Rapid Thermal Processing

To exhibit high flux and high selectivity for energy efficient membrane separation processes, thin and defect-free zeolite membranes on a porous support must be fabricated. Experimental efforts have been directed to the confined synthesis of zeolite particles to be used as a seed layer for the secondary hydrothermal growth of membranes, primarily due to controllable size and good monodispersity of the seed particles. Here, we present a facile method to fabricate MFI zeolite membranes with high flux (ca. 2.6×10^-7 molm^-2s^-1Pa^-1) and high separation factors (SF, 123–139 and in one case as high as 335) for xylene isomer separation by optimizing seed deposition and calcination processes. Zeolite nanoparticles prepared by aforementioned confined syntheses were deposited as randomly oriented seed layers on porous supports by rubbing and leveling methods to obtain thin zeolite films (400–500 nm) after secondary hydrothermal growth. Rapid thermal processing (RTP) was used in a single calcination step that substantially reduced processing times and energy usage and improved the separation efficiency of the membranes.