Scalable One-Step Gel Conversion Route to High-Performance CHA Zeolite Hollow Fiber Membranes and Modules for CO2 Separation

Efficient separation of CO2 from other molecules such as CH4, N-2, and hydrocarbons is a key problem in many energy production and greenhouse gas reduction schemes. Zeolite materials demonstrate attractive gas separation properties, but their industrial application as membranes in gas separation are elusive because of high cost and low reproducibility of conventional fabrication techniques. A facile method is demonstrated for the fabrication of high-silica CHA zeolite membranes on low-cost alumina hollow fiber substrates by a one-step direct gel conversion method, along with a detailed characterization of the CHA hollow fiber membranes. To demonstrate the scalability of the method, 20 hollow fiber (710 mu m OD and 390 mu m ID) membranes are synthesized in the same batch and assembled into a module. Under dry conditions, the membranes show an excellent CO2 permeance up to 3500 GPU (1 Gas Permeation Unit = 3.348 x 10(-10) mol m(-2) s(-1) Pa-1) and an excellent CO2 separation performance (e.g., CO2/CH4 separation factors up to 210 in the 1-7 bar feed pressure range). In addition, the membranes exhibit a considerable increase in CO2 selectivity under humid (saturated water vapor) conditions with moderate permeance drops. This study opens a promising new path for accelerated development of low-cost zeolitic membranes for gas separation technology.