Fabrication of zeolite/polymer composite membranes in a roller assembly

摘要

Membranes are cost-effective solutions for many industrial separations. Polymer membranes are widely used in gas separations. Because of the solubility-diffusion mechanism of transport, the permeance and selectivity of polymer membranes are inversely related, and is considered a limitation. Zeolite membranes do not have this limitation, but zeolite membrane synthesis is a batch process with long synthesis times and presence of defects. The resulting high costs of manufacture make zeolite membranes noncompetitive for most applications. In this study, we present a roll-to-roll method for zeolite synthesis on a polymer support exploiting a gel that leads to rapid zeolite crystallization and a bendable zeolite membrane structure. Membranes were grown under both compressive and tensile stress, and with zeolite structure both on top and within the pores of the polyethersulfone (PES) support. The structure of the membranes was evaluated by electron microscopy. Membranes were coated with a thin layer of polydimethylsiloxane, and evaluated for CO2/N-2 separation, relevant for CO2 capture from flue gas of power plants. As long as the zeolite membrane is grown within the PES support, highly reproducible CO2/N-2 separation performance with CO2 permeance of 1881 +/- 204 GPU and CO2/N-2 selectivity of 34 +/- 4 was observed immaterial of the stress conditions under which it was grown. For zeolite membrane grown on top of the PES support, the compressive stress resulted in crack formation, with poor transport properties. Demonstration of zeolite membrane fabrication with roll-to-roll method has the potential for industrial level scale up. (C) 2015 Elsevier Inc. All rights reserved.