ADSORBENT FILLED MEMBRANES FOR GAS SEPARATION .1. IMPROVEMENT OF THE GAS SEPARATION PROPERTIES OF POLYMERIC MEMBRANES BY INCORPORATION OF MICROPOROUS ADSORBENTS

The effect of the introduction of specific adsorbents on the gas separ ation properties of polymeric membranes has been studied. For this pur pose both carbon molecular sieves and zeolites are considered. The res ults show that zeolites such as silicate-1, 13X and KY improve to a la rge extent the separation properties of poorly selective rubbery polym ers towards a mixture of carbon dioxide/methane. Some of the filled ru bbery polymers achieve intrinsic separation properties comparable to c ellulose acetate, polysulfone or polyethersulfone. However, zeolite 5A leads to a decrease in permeability and an unchanged selectivity. Thi s is due to the impermeable character of these particles, i.e. carbon dioxide molecules cannot diffuse through the porous structure under th e conditions applied. Using silicate-1 also results in an improvement of the oxygen/nitrogen separation properties which is mainly due to a kinetic effect. Carbon molecular sieves do not improve the separation performances or only to a very small extent. This is caused by a mainl y dead-end (not interconnected) porous structure which is inherent to their manufacturing process.