Polymer could improve natural gas purification

Natural gas requires heavy processing to remove carbon dioxide and other impurities before it can be used for fuel. Many processing plants use low-cost polymer membranes to remove carbon dioxide. Researchers have now developed a new polymer with hourglass-shaped pores that can do the job more efficiently than standard polymers do.

Membranes used for gas separation have pores that let through some molecules but not others. However, variations in the size and shape of the pores reduce the membranes’ efficiency. Chemical engineer Ho Bum Park at the University of Texas at Austin and his colleagues have designed a polymer with uniform pores.

The hourglass shape of the new polymer’s pores mimics that of water channels called aquaporins found in cell membranes. These channels let water molecules pass in and out of the cell while blocking the passage of other molecules. In the new polymer, the pores’ large mouths allow large amounts of natural gas to collect on the membrane’s surface, while their narrow channels let only small molecules of carbon dioxide slip through, says Park.

The polymer is four times more efficient than conventional polymers at separating out carbon dioxide and a few hundred times faster at letting the smaller gas molecules pass through. Park and his colleagues describe their new plastic in the October 12 Science.