Hetero-epitaxial growth of chabazite zeolite membranes using an RHO-type seed layer

High-quality chabazite (CHA) zeolite membranes were synthesized from organotemplate-free aluminosilicate gel via epitaxial growth using RHO-type seed layer. Both zeolite RHO seeds (Si/Al = 2.4) and the synthetic gel containing cesium species led to the formation of the CHA zeolite with a high Si/Al ratio of 3.0 and a short synthesis time of 12 h. The effects of seed particles and crystallization time on membrane formation, pervaporation performance, and acid resistance were also investigated. The obtained CHA@RHO membrane prepared using commercial tubular mullite support showed a high flux of 2.3 kg m⁻² h⁻¹ and a good separation factor of 3500 for 10/90 wt% water/ethanol mixture at 348 K, which are comparable to those of homogeneous CHA membranes crystallized in organotemplate-free systems from previous reports. Moreover, these membranes were stable for the dehydration of acidic aqueous ethanol solution (with a pH value of 3.0) at 348 K for 8 d.