Scale-up of amine-containing membranes for hydrogen purification for fuel cells

Abstract

Fabrication of amine-containing membranes for removal of H2S and CO2 from reformate gas for hydrogen purification for fuel cells was scaled up by using a continuous roll-to-roll membrane fabrication machine. The membrane contained aminoisobutyric acid-potassium salt as the mobile carrier and polyvinylamine as the fixed-site carrier for facilitated transport of acid gases in crosslinked polyvinylalcohol as the membrane matrix. Three key variables controlling the membrane selective layer thickness, i.e., the coating solution, substrate web coating speed, and coating knife gap setting, were identified and studied. Membranes in 14 in. in width and > 150 feet in length were fabricated with a uniform selective layer thickness of around 15 µm. The scale-up membranes demonstrated similar performances as the lab-scale membranes with a CO2 permeance of more than 200 GPU, CO2/H2 selectivity of greater than 200, and H2S/H2 selectivity of higher than 600. The scale-up membranes were used for the fabrication of prototype spiral-wound membrane modules for a field test with autothermal reformate gas as the feed gas. The modeling and optimization of the hydrogen purification process were performed to identify the optimum test conditions for the spiral-wound membrane modules. The modeling results showed that the membrane removed H2S to less than 10 ppm and CO2 to < 1% in the hydrogen product with more than 99% of H2 recovery for the case of using a wet sweep gas with 40% moisture. The field test results showed that the H2S and CO2 concentrations were about 4–10 ppm and < 3%, respectively, in the hydrogen product on a wet basis and that the agreement between the modeling results and the test results was reasonably good.