Separating hydrocarbons using reverse osmosis

Abstract

A membrane that separates organic solvent molecules based on their shape and size could dramatically cut costs associated with preparing valuable polymer feedstocks, such as p-xylene. It works as part of a reverse-osmosis process, a common method for water desalination that hasn’t been applied to organic solvents until now. Both the membrane and the organic solvent reverse-osmosis process were developed by Ryan P. Lively and Dong-Yeun Koh of Georgia Tech, along with Benjamin A. McCool and Harry W. Deckman of ExxonMobil Research & Engineering. The researchers started with a commercially available hollow fiber made of poly(vinylidene fluoride). The fiber consists of a tube of support material full of microscale pores surrounded by a membrane riddled with molecule-sized pores. This porous material is incompatible with organic solvents, so the researchers converted it to an all-carbon substance, called a carbon molecular sieve, by heating it to 550 °C. But before they did