Studies involving high temperature desulfurization/regeneration reactions of metal oxides for fuel cell development. Final report

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Abstract
Research conducted at Giner, Inc. during 1981 to 1983 under the present contract has been a continuation of the investigation of a high temperature regenerable desulfurization process capable of reducing the sulfur content in coal gases from 200 ppM to 1 ppM. The overall objective has been the integration of a coal gasifier with a molten carbonate fuel cell, which requires that the sulfur content be below 1 ppM. Commercially available low temperature processes incur an excessive energy penalty. Results obtained with packed-bed and fluidized bed reactors have demonstrated that a CuO/ZnO mixed oxide sorbent is regenerable and capable of lowering the sulfur content (as H/sub 2/S and COS) from 200 ppM in simulated hot coal-derived gases to below 1 ppM level at 600 to 650/sup 0/C. Four potential sorbents (copper, tungsten oxide, vanadium oxide and zinc oxide) were initially selected for experimental use in hot regenerable desulfurization in the temperature range 500 to 650/sup 0/C. Based on engineering considerations, such as desulfurization capacity in per weight or volume of sorbents, a coprecipitated CuO/ZnO was selected for further study. A structural reorganization mechanism, unique to mixed oxides, was identified: the creation of relatively fine crystallites of the sulfided components (Cu/submore » 2/S and ZnS) to counteract the loss of surface area due to sintering during regeneration. Studies with 9 to 26% water vapor in simulated coal gases show that sulfur levels below 1 ppM can be achieved in the temperature range of 500/sup 0/ to 650/sup 0/C. The ability of CuO/ZnO to remove COS, CS/sub 2/ and CH/sub 3/SH at these conditions has been demonstrated in this study. Also a previously proposed pore-plugging model was further developed with good success for data treatment of both packed bed and fluidized-bed reactors. 96 references, 42 figures, 21 tables. « less

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