Porous ceramic membranes for propane-propylene separation via the π-complexation mechanism: unsupported systems

The purpose of this work is the utilization of the selective π-complexation interactions exhibited between certain metal cations and the double bond of the olefins, in order to develop membrane materials for a continuous propane-propylene separation process. Mesoporous γ-Al2O3 and microporous SiO2 membranes are synthesized by the sol-gel method and subsequently modified with Ag+ by impregnation from silver nitrate solutions. Gas separation experiments of equimolar undiluted propane-propylene mixtures resulted in maximum separation factors of 1.3 for the mesoporous systems. For the microporous systems the maximum separation factor achieved was 7.7, which is one of the highest reported in the literature for porous ceramic membrane systems.