Effect of synthesis parameters on single gas permeation through T-type zeolite membranes

In this research, nanoporous zeolite T membranes were synthesized at three levels of synthesis temperature: 100, 120 and 140 degrees C and synthesis time: 15, 30 and 50 h and characterized by gas permeation. Effects of synthesis parameters on CO2 and CH4 permeances and CO2/CH4 ideal separation factors were studied. All experiments were conducted at I bar feed pressure and 30 degrees C module temperature. Normally, it is anticipated that increasing synthesis temperature and synthesis time increase gas permeances and consequently decrease ideal separation factor. This prediction was not observed in the case of synthesis temperature increase from 100 to 120 degrees C as well as synthesis time increase from 15 to 30 h, due to the dual effect of increasing synthesis temperature and synthesis time on gas permeances and ideal separation factor. More zeolites are deposited and larger crystals are formed at higher synthesis temperatures and times. Forming the larger crystals accelerates the rate of zeolite layer integration, which is responsible for gas separation, in one hand and reduces the density of deposited zeolite layer on the support, due to the formation of more voids, on the other hand. In terms of maximizing the CO2/CH4 ideal separation factor, medium synthesis temperature and synthesis time (120 degrees C and 30h) can be selected, however, maximum gas permeances are obtained at low levels of synthesis temperature and time (100 degrees C and 15 h). According to the ranges of gas permeances (10(-11) to 10(-6) mol/m(2) s Pa) and CO2/CH4 ideal separation factors (1.4-70.3), it is concluded that the zeolite T membranes synthesized at optimum conditions can be employed for membrane separation of CO2/CH4 mixtures. (C) 2008 Elsevier Ltd. All rights reserved.