Modeling Permeation of CO2/CH4, CO2/N2, and N2/CH4 Mixtures Across SAPO-34 Membrane with the Maxwell−Stefan Equations

The objective of this paper is test the capability of the Maxwell−Stefan (M−S) diffusion formulation to predict binary mixture permeation fluxes across a SAPO-34 membrane using only data on pure-component adsorption isotherms and diffusivities. Experiments were carried out for permeation of CO 2 /CH 4, CO 2 /N 2, and N 2 /CH 4 mixtures across a SAPO-34 membrane with upstream pressures ranging to 7.2 MPa, ensuring that high occupancies within the zeolite layer are reached. Good agreement between the M−S mixture model and experiments are obtained provided the binary exchange coefficients Đ 12 in the M−S equations are assumed to have high enough values to ensure that intercage hops of the species occur independently of one other.