PERVAPORATION SEPARATION OF METHYL TERT-BUTYL ETHER METHANOL MIXTURESUSING A HIGH-PERFORMANCE BLENDED MEMBRANE/

For the separation of methyl tert-butyl ether (MTBE) and methanol mixt ures, we investigated the pervaporation performance of a blend membran e made from cellulose acetate and cellulose acetate hydrogen phthalate . At first the influence of the blend composition was studied with a c ertain feed mixture. We found that all the tested membranes permeate m ethanol preferentially. The selectivity increases and the permeation r ate decreases with increasing cellulose acetate content in the blend. Therefore, an optimal blend composition of 30 wt % in cellulose acetat e was chosen to evaluate the influence of the feed composition and the experimental temperature on the pervaporation performance. When the f eed temperature or the methanol content in the feed increases, the per meation rates are greatly enhanced and the selectivity decreases. Howe ver, the temperature effect is more significant at low methanol conten t in the feed and becomes negligible at high methanol content in the f eed where plasticity effects prevail. A comparison, carried out with a ll the membranes until now used for the separation of MTBE/methanol mi xtures, showed that the blended membrane studied in this present work presents good permselective properties. (C) 1997 John Wiley & Sons, In c.