SEPARATION OF MTBE-METHANOL MIXTURES BY PERVAPORATION

Membranes made of a polymer blend of poly(acrylic acid) and poly(vinyl alcohol) were evaluated for the separation of methanol from methyl te rt-butyl ether (MTBE) by pervaporation. The influence of the blend com position and the feed composition on the pervaporation performance wer e investigated. Methanol permeates preferentially through all tested b lend membranes, and the selectivity increases with increasing poly(vin yl alcohol) content in the blends. However, a flux decrease is observe d with increasing poly(vinyl alcohol) content. With increasing feed te mperature the flux increases, and the selectivity remains constant. In addition, the influence of crosslinking on the permselectivity was in vestigated. The pervaporation flux decreases with increasing crosslink ing density, but the selectivity is enhanced. This is due to a;more ra pid decrease in the component flux of MTBE compared to that of methano l.