Effect of Light Gas Components on CO2 Permeation through DD3R Membranes

Membrane technology has emerged to be a promising alternative for natural gas upgrading. Zeolite membranes are attracting more and more attention because of the hydrothermal and chemical stability. However, the zeolite membranes are generally evaluated in the unary or binary CO2/CH4 components, which is far from the real applications. Herein we investigated the CO2 permeation through DD3R zeolite membranes under the presence of light gas components (e.g., N2, CH4, C2H6, and SF6). The CO2 diffusivity was calculated by the generalized Maxwell-Stefan model for more insights on CO2 transport. The diffusion of CO2 molecules was slightly affected by the presence of N2, CH4, and SF6. However, the CO2 diffusivity in equimolar CO2/C2H6 was one magnitude lower than that of pure CO2 component because of the strong competitive adsorption and slow diffusion of C2H6 molecules. An empirical formula was proposed to predict the CO2 diffusivity in the CO2/CH4/C2H6 ternary mixture. The predicted CO2 flux matched well with the experimental one for the mixture containing less than 15 mol % C2H6. This would provide a facile method to determine the required membrane area for multicomponent mixture separation.