Effect of Light Gas Components on CO₂Permeation 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/CH₄components, which is far from the real applications. Herein we investigated the CO₂permeation through DD3R zeolite membranes under the presence of light gas components (e.g., N₂, CH₄, C₂H₆, and SF₆). The CO₂diffusivity was calculated by the generalized Maxwell-Stefan model for more insights on CO₂transport. The diffusion of CO₂molecules was slightly affected by the presence of N₂, CH₄, and SF₆. However, the CO₂diffusivity in equimolar CO₂/C₂H₆was one magnitude lower than that of pure CO₂component because of the strong competitive adsorption and slow diffusion of C₂H₆molecules. An empirical formula was proposed to predict the CO₂diffusivity in the CO₂/CH₄/C₂H₆ternary mixture. The predicted CO₂flux 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.