There is a great need for improvements in efficient methods to reduce the cost of removing carbon dioxide from flue gas and natural gas at the wellhead. Membrane-based carbon dioxide extraction has the advantage of high separation efficiency, mild operating conditions, and low energy requirements. Facilitated transport membranes improve permeability and selectivity over traditional permselective membranes. The use of enzymes as the facilitating agent, because of their great specificity and very high rates, further enhances selectivity. Phase I will create an enzyme-facilitated membrane core by immobilizing the enzyme to an ultra-high gas transport membrane in order to limit solvent loss and prevent fouling. The feasibility of this system will be demonstrated under controlled laboratory conditions. New, naturally occurring, extremophile gas transfer enzymes will also be isolated. Computational modeling will be done to study site-directed mutagenesis of well-characterized isozymes. These enzymes will be tested for stability under simulated gas flow conditions. Candidate enzymes will be immobilized to high-permeability membranes, and the associated gas flux will be measured in the laboratory. The Phase II project will immobilize a number of preferred candidate enzymes isolated in Phase I, and gas flux will again be measured. Tests will involve gas simulation mixtures. On successful completion the next step will be to proceed to small-scale field trials.
Commercial Applications and Other Benefits as described by the awardee:The use of natural gas as a fuel and a feedstock is growing in importance. Satisfying demand means accessing new fields many of which have acid gas. More efficient removal of carbon dioxide should reduce the cost of domestic gas. Environmental clean-up of carbon dioxide is equally important. Beyond domestic use, technology developed in Phase I and II could be exported for use abroad.
