Novel Membranes for In-Process Recycling of Hydrocarbon Feedstocks in Oxygen-Oxidation Processes

Oxygen-oxidation processes are used to produce a number of important chemicals, including ethylene oxide, propylene oxide, terephthalic acid, and vinyl chloride. Approximately 450 million lbs/yr of the hydrocarbon feedstocks used in these processes are lost as part of an inert gas purge stream from the reactor. Currently, this gas is flared, which results in a loss of valuable chemicals and an increased environmental burden. This project involves the development of selective membranes that retain the hydrocarbon feedstock for recycling to the reactor while permeating the inert gases. The value of the recovered hydrocarbon leads to process payback times of 12 to 24 months. Preliminary work already has produced membranes with selectivities close to the target performance required. In the Phase I project, candidate polymers will be fabricated into thin composite membranes. Laboratory-scale membrane stamps then will be tested with model gas mixtures.