This Small Business Innovative Research (SBIR) Phase II project focuses on the separation of light hydrocarbon mixtures-specifically, propylene/propane mixtures-by membrane pervaporation. A preliminary analysis indicated that the recovery of propylene from reactor purge gas streams using separation systems based on these materials is economically attractive. These purge streams are numerous-more than 400 streams of this type exist worldwide - but too small to be treated by distillation. Nonetheless, the amount of propylene involved is substantial. An estimated 685 million pounds of propylene are recoverable from reactor purge streams in the United States alone. In the Phase II project, the current best membrane will be optimized, scaled up and formed into bench-scale membrane modules.<br/><br/>This project involves the separation of propylene/propane mixtures; application to the separation of many other mixtures is possible. The proposed membrane pervaporation process addresses a market need - the economical recovery of propylene, a valuable chemical feedstock, from propane-containing waste gas streams that cannot be satisfied by alternative technologies.