Separation of CO2 and N2 on Zeolite Silicalate-1 Membrane Synthesized on Novel Support

Abstract

This paper reports on the properties of an MFI-type zeolite (silicalite-1) membrane synthesized on a novel tubular support with a 0.45 µm-pore size active layer consisting of zirconium and titanium oxides. Even though the membrane was synthesized by a pore plugging method, apart from penetrating into the support, the silicalite-1 crystals formed a 1.5 µm layer on top of the support. After the zeolite synthesis, the Si constituted more than 35% of the active layer of the support, which implies small size and close packing of the silicalite-1 crystals in the pores of the active layer. Single gas permeation tests with N2 and CO2 revealed comparable N2 and CO2 permeances. On the other hand, CO2/N2 gas separation tests performed at different total feed pressures and feed compositions lead to CO2/N2 permselectivities as high as 26.0, with the corresponding CO2 permeance of 6 × 10−8 mol/m2 Pa s. The effects of changing the partial pressure gradient of CO2 across the membrane by means of varying the total feed pressure and the feed composition on the CO2 permeance and CO2/N2 permselectivity are discussed.