The objective of this study is to develop an intensified high temperature gas separation technique with emphasis on oxygen separation from air and hydrogen separation from syngas. These two processes are important in gasification and I subsequent conditioning of syngas in order to enhance hydrogen yield. Oxygen powered gasification and the control of syngas composition are important in the development of intensified integrated BioRefinery (IIBR) technology in which gasification, syngas cleaning and hydrogen enhancement are central processes. In IIBR, thermally, mechanically and chemically stable membrane systems for high temperature gas separation are required. In this study, by using electroless deposition process, we developed novel supported hydrogen selective palladium! silver membrane modules and oxygen selective perovskite based membranes modules which are mechanically, thermally and chemically stable in order to separate hydrogen from syngas and oxygen from air at high temperatures with chemical reaction on the permeate side. The thickness of the hydrogen membrane layer is ea. 20-75 urn; however the thickness of oxygen membranes is about 200-2000 urn. The mechanical, chemical and thermal stability of the membranes was achieved through a sandwiching process in which the membrane was placed between two catalytic nano-structured micro-porous materials and sealed against gas leakage. The performance of the catalytic sandwiched palladium based hydrogen membrane was evaluated and compared with commercial membrane of the same composition and thickness. It was shown that the sandwiched membrane had better permeability coefficients and gave up to 40% higher hydrogen flux compared with commercial membranes. Unlike the commercial membrane, sandwiched membrane between two catalytic nano-structured micro-porous materials provided good mechanical properties and high chemical stability for the membrane during 15 days of testing. Catalytic layers not only provided mechanical, thermal and chemical protection but also helped hydrogen dissociation on the feed side of the membrane thus enhancing flux. Perovskite type oxygen selective sandwiched membranes were produced and tested \ for gas tightness at 600 QC and 15 bar without any failure. Membrane structure was determined by scanning electron microscopy and x-ray diffraction.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:579512 |
| Date | January 2011 |
| Creators | El Naggar, Ahmed Metwally Ali |
| Publisher | University of Newcastle Upon Tyne |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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