Crosslinked PEG and PEBAX Membranes for Concurrent Permeation of Water and Carbon Dioxide

Membrane technology can be used for both post combustion carbon dioxide capture and acidic gas sweetening and dehydration of natural gas. These processes are especially suited for polymeric membranes with polyether functionality, because of the high affinity of this species for both H(2)O and CO(2). Here, both crosslinked polyethylene glycol diacrylate and a polyether-polyamide block copolymer (PEBAX 2533(©)) are studied for their ability to separate CO(2) from CH(4) and N(2) under single and mixed gas conditions, for both dry and wet feeds, as well as when 500 ppm H(2)S is present. The solubility of gases within these polymers is shown to be better correlated with the Lennard Jones well depth than with critical temperature. Under dry mixed gas conditions, CO(2) permeability is reduced compared to the single gas measurement because of competitive sorption from CH(4) or N(2). However, selectivity for CO(2) is retained in both polymers. The presence of water in the feed is observed to swell the PEG membrane resulting in a significant increase in CO(2) permeability relative to the dry gas scenario. Importantly, the selectivity is again retained under wet feed gas conditions. The presence of H(2)S is observed to only slightly reduce CO(2) permeability through both membranes.