|We are developing dense cermet (i.e., ceramic-metal composite) membranes for separating hydrogen from product streams generated during coal gasification. Hydrogen separation with these membranes is nongalvanic, and hydrogen separated from the feed stream is of high purity, so post-separation purification steps are unnecessary. Using several feed gas mixtures, we measured the hydrogen permeation rate, or flux, for the membranes in the temperature range of 500-900°C. This rate varied linearly with the inverse of membrane thickness and reached ≈33 cm3[STP]/min-cm2 at 900°C for an ≈15-μm-thick membrane when 100% H2 at ambient pressure was used as the feed gas. When membranes were tested in a gas mixture that contained CH4, CO, and CO2 for times that approached ≈500 h, performance did not degrade. We also tested the membranes in gas mixtures containing H2, CH4, CO2, CO, and H2S. Hydrogen flux measurements showed that at 900°C, the membranes are stable for up to 1200 h in gases that contain 400 ppm H2S. The present status of membrane development will be presented in this talk. |
Work supported by the U.S. Department of Energy, Office of Fossil Energy, National Energy Technology Laboratory's Hydrogen and Syngas Technology Program, under Contract DE-AC02-06CH11357.
Coal Conversion to Clean Liquid and Gaseous Fuels
1:25 PM-8:20 PM, Monday, August 20, 2007 Boston Park Plaza -- Chartes River Room, Oral