Temperature and pressure effects on CO 2 and CH 4 permeation through MFI zeolite membranes (original) (raw)

Single gas and mixture permeances of CO 2 and CH 4 were measured as functions of pressure and temperature through three MFI zeolite membranes that have different fractions of their permeances through non-zeolite pores. The effect of pressure on CO 2 permeance, which was different for each membrane, was ®t by a modi®ed surface diffusion model. The differences in the pressure behavior of the membranes are attributed to pores with viscous and Knudsen¯ow. Membranes with the largest permeation through non-zeolite pores have the lowest CO 2 /CH 4 mixture selectivity. The highest CO 2 /CH 4 mixture selectivity is 5.5 at room temperature and decreases with temperature because of a decrease in competitive adsorption. Although increasing pressure at constant pressure drop increases the apparent CO 2 /CH 4 selectivity, the ratio of the CO 2 and CH 4¯u xes decreases. # 0376-7388/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 6 -7 3 8 8 ( 9 9 ) 0 0 0 7 3 -3