Hydrogen separation by dense cermet membranes

• Published in: Fuel (Guildford) Vol. 85; no. 2; pp. 150 - 155
• Main Authors: Balachandran, U., Lee, T.H., Chen, L., Song, S.J., Picciolo, J.J., Dorris, S.E.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 2006; Elsevier
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Cermet; Dense membranes; Energy; Exact sciences and technology; Fuels; Hydrogen; Hydrogen permeation; Hydrogen permeation; Dense membranes; Cermet; Methane; Gas permeability; Hydrogen; Coal; Membrane; Gasification; Performance; Synthesis gas
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2005.05.027

Novel cermet (i.e. ceramic–metal composite) membranes have been developed to separate hydrogen from mixed gases, particularly product streams generated during coal gasification and/or methane reforming. Hydrogen separation with these membranes is non-galvanic, i.e. it does not use electrodes or an external power supply to drive the separation, and hydrogen selectivity is nearly 100% because the membranes contain no interconnected porosity. The hydrogen permeation rate has been measured as a function of temperature (500–900
°C), membrane thickness (≈22–210
μm), and partial pressure of hydrogen (0.04–1.0
atm) in the feed gas. The hydrogen flux varied linearly with the inverse of membrane thickness, and reached ≈20
cm
3(STP)/min
cm
2 for a membrane with a thickness of ≈22
μm at 900
°C with 100% H
2 (at ambient pressure) as the feed gas. The results indicate that the hydrogen flux is limited by bulk diffusion and might be higher for a thinner (<22
μm) membrane. Some of the membranes were tested in a simulated syngas mixture containing H
2, CO, CO
2, and CH
4, and showed no degradation in performance. Hydrogen flux measurements made in H
2S-containing atmospheres for times approaching ≈270
h showed that a 200-μm-thick cermet membrane was stable in gases containing up to ≈400
ppm H
2S. While longer-term studies are needed, these results suggest that the cermet membranes may be suitable for practical hydrogen separation applications.