Electrochemical oxidation of H2S to give sulfur and water was achieved at 900~ using fuel cells possessing the general configuration H2S, anode electrocatalyst/( 8 stabilized ZrO2 /La Sr Mn ~ /Pt, 02 (air) w/o Y208 or 5 w/o CaO) / 0.89 0.11 ,-'8 where anode electrocatalysts experimentally investigated for promoting the subject oxidation reaction included WS2 and the thiospinels CuNi~S4, CuC02S,, CuFe2S,, NiCozS4, and NiFe2S4. The predominant oxidizable electroactive species present in the fuel cell anode compartment was suggested to be hydrogen originating from the initial thermal dissociation of H2S (H2S ~ H2 + 1/2 $2) at fuel cell operating temperatures. Rapid anode kinetics were found for the anodic reaction with the empirical trend for exchange currents (io) per geometric area being found to be: NiFe2S, > WS2 > CuC02S4 > CuFe2S, NiCo2S4 > CuNi2S,.Currently, large quantities of hydrogen sulfide are generated as a by-product from both coal gasification/liquifaction and heavy oil desulfurization processes. These sources currently constitute greater than 50% of sulfur pro-* Electrochemical Society Active Member. duced in the United States per year. Sulfur removal during coal gasification is achieved using the well-established Claus process (1) where H2S is partially oxidized by air to give unit activity sulfur and water. The overall chemical reaction which occurs at 525~176 can be summarized as follows

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Combined processing of coal with heavy petroleum crudes and residua has been investigated. Evaluation of the reaction parameters of temperature, hydrogen pressure, time, and catalyst extrudate size has been undertaken. On the basis of the production of pentane soluble oil and coal conversion, feasible parameters are established: 425 'C, 1250 psig H, pressure at ambient temperature, long reaction time, and a hydrogenation catalyst with a small particle size. Combined processing is shown to be sensitive to catalyst extrudate size, with powdered catalyst giving substantially more oil yield and coal conversion than the extrudates.The combined processing of coal and heavy petroleum crudes and residua can provide efficient utilization of difficult to refine heavy petroleum materials. Combined processing can also provide a viable method for the production of synthetic fuels from coal. Coprocessing could lead to the refineries of the future into which both coal and crude petroleum materials are fed simultaneously. When coal and crude together are used as feedstocks, the yield of distillate liquid products per barrel of heavy petroleum crude or residua would be increased along with increased conversion of the petroleum asphaltenes. The end product obtained would be a combination of materials from residuum and from coal which could then be further refined. Because of the source of these materials, secondary hydrotreatment at higher severities than conventional refining may be required.One of the advantages of coprocessing compared to current coal liquefaction processing technology is that the requirement for maintenance of a sufficient amount of high quality recycle solvent could be relaxed. The use of the petroleum coprocessing solvent could either totally eliminate or reduce the amount of solvent recycle needed for effective processing, thereby reducing the cost of the recycle and of the final end product. The concept of coprocessing thus allows greater flexibility and potential for economic improvement in the production of synthetic fuels from coal.Recent work in the coprocessing of coal and heavy petroleum crudes and residua performed by Curtis et al. (1985) has shown that a substantial amount of coal conversion can be obtained at liquefaction conditions in the presence of a hydrotreating catalyst. In a catalytic environment, the yields of pentane-soluble material from the combined processing were increased over that of the initial feed blend, suggesting that the simultaneous upgrading of coal and the petroleum heavy ends was occurring. Typical coal liquefaction conditions were used in that work, but the conditions were not optimized. A previous investigation by Moschopedis et al. (1982) has shown that proper selection of reaction parameters is required for obtaining the highest quality product slate when processing coal with heavy oils and bitumen. These researchers have examined the effect of process parameters on the upgrading of an Alberta high volatile C bituminous coal with heavy oil and bitumen. The optimal p...

Measurements of effective intraparticle diffusivity were made by using aged catalysts withdrawn at various times from coal liquefaction expanded-bed hydrotreaters. Artifically aged catalysts from the laboratory were also used. Depending on the feed properties and the catalyst age, the effective intraparticle diffusivities were reduced, by up to 2 orders of magnitude, as compared to the corresponding values with the fresh catalyst. The data suggest a significant increase in catalyst pellet tortuosity because of deposition of materials inside pores during hydroprocessing activities, indicating a contributing factor to catalyst deactivation. The intraparticle diffusivity values could be partially restored through controlled oxidative regeneration.

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