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DC Field | Value | Language |
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dc.contributor.advisor | Kay, D.A.R. | en_US |
dc.contributor.author | Meng, Veronica Marie Valerie | en_US |
dc.date.accessioned | 2014-06-18T16:33:36Z | - |
dc.date.available | 2014-06-18T16:33:36Z | - |
dc.date.created | 2010-05-04 | en_US |
dc.date.issued | 1985-03 | en_US |
dc.identifier.other | opendissertations/1288 | en_US |
dc.identifier.other | 2410 | en_US |
dc.identifier.other | 1296653 | en_US |
dc.identifier.uri | http://hdl.handle.net/11375/5948 | - |
dc.description.abstract | <p>The high temperature gaseous desulphurization characteristics of calcined bastnaesite concentrates and cerium oxides have been investigated. The former is a solid solution of rare earth oxyfluorides (RE = La, Nd, Pr) and CeO₂, and has a fluorite type structure. The presence of dissolved CeO₂ in these concentrates is believed to be responsible for the reduction, desulfurization and regeneration characteristics of this mineral.</p> <p>The chemistry of the desulfurization and regeneration process has been elucidated using a fixed bed of cerium oxide at high temperatures (800-1000°C). Coal gases, similar in composition to those generated by a Koppers-Totzek gasification unit, were desulfurized from 1.0% H₂S by volume to less than 4 ngS/mL (3 ppm) in a laboratory scale reactor. This represents a desulfurization efficiency of 99.98%. Desulfurization takes place through a non-catalytic gas-solid reaction where the reactant is in the form of a non-stoichiometric oxide, CeO₂_n.</p> <p>2CeO₂_n(s) + (1-2x)H₂(g) = Ce₂O₂S(s) + 2(1-x)H₂O(g)</p> <p>Adsorption of sulfur is facilitated by the presence of oxygen vacancies in the reduced sorbents. An interactive computing system was used in conjunction with the Ce-O-S phase stability diagram to predict the compositions of reactants and products in terms of the sulfur and oxygen potentials of the gas phase.</p> <p>Regeneration of spent sorbents occurs readily in air, with the evolution of sulfur dioxide:</p> <p>Ce₂O₂S(s) + O₂(g) = 2CeO₂(s) + SO₂(g)</p> <p>Desulfurization efficiencies of cerium oxide compared favourably with those of similar high temperature technologies using iron oxide, limestone or dolomite.</p> | en_US |
dc.subject | Chemical Engineering | en_US |
dc.subject | Chemical Engineering | en_US |
dc.title | High Temperature Gaseous Desulfurization Using Cerium Oxides and Bastnaesite Concentrates | en_US |
dc.type | thesis | en_US |
dc.contributor.department | Chemical Engineering | en_US |
dc.description.degree | Doctor of Philosophy (PhD) | en_US |
Appears in Collections: | Open Access Dissertations and Theses |
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fulltext.pdf | 4.06 MB | Adobe PDF | View/Open |
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