Stable oxygen-selective sorbents for air separation

,Commercial sorption-based air separation is usually done using nitrogen selective zeolites in pressure swing adsorption (PSA) systems. Separation of air by adsorption of less abundant oxygen is more desirable. In this study we have developed some stable oxygen selective sorbents with silver and cerium salts. AgCl, AgBr, AgI and CeCl3 all showed stable adsorption characteristics with pure, component selectivity Of O-2/N-2 similar to 2.0-3.0 at 1 atm. For these salts heat of adsorption of oxygen was found to be slightly higher than that of nitrogen, which was also predicted by ab initio molecular orbital calculations by Chen and Yang (Ind. Eng. Chem. Res. 35 (1996) 4020). The adsorption capacity of these salts was increased by thermal dispersion on high surface area SiO2 support. AgBr thermally spread on SiO2 is the best sorbent obtained in this study. AgBr/SiO2 (1.0g/g) showed a pure component oxygen selectivity of similar to 3 at 1 atm and similar to 5 at 7atm. PSA simulations were used to show the feasibility of nitrogen production using AgBr/SiO2. (C) 2004 Elsevier Ltd. All rights reserved.