Separating molecules by size in SAPO-34 membranes

CATEGORY: SAPO-34 
Separating molecules by size in SAPO-34 membranes

Type	Journal Article
Author	Hans H. Funke
Author	Michael Z. Chen
URL	http://www.sciencedirect.com/science/article/pii/S0376738814000453
Volume	456
Pages	185-191
Publication	Journal of Membrane Science
Date	April 15, 2014
Abstract	SAPO-34 membranes that have CO2/CH4 separation selectivities of ~100 at 295 K and pressures up to 4.6 MPa also exhibit high molecular sieving separations of mixtures containing i-butane or CF4. The separation selectivities were 15,000–20,000 for CO2/i-butane from 295 to 420 K, and 12,000–20,000 for CO2/CF4 for feed pressures up to 0.5 MPa at 295 K. These may be the highest gas-phase separation selectivities reported for zeolite membranes, and they are likely lower limits because of concentration polarization, leakage around O-rings, and i-butane diffusion through the silicone O-rings. In these separations, both He and H2 appear to speed up CH4 permeation, as expected from molecular simulations reported previously. Also, CH4 appears to slow diffusion of CO2, He, and H2.