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Fixed bed testing of a molybdenum-promoted zinc titanate for hot gas desulfurization

Description: The following conclusions were made, based upon this study of T-2535 molybdenum-promoted zinc titanate: (1) Results of the half-cycle sulfidation experiments showed that sorbent efficiency and capacity of this formulation of zinc titanate were weak functions of operating-bed temperature. Evidence of diffusion limitations on the sulfidation reaction were observed, particularly at superficial velocities greater than 30 cm/s (1 ft/s). Sorbent performance appeared to be affected by the concentration of reducing gases and/or water content of the simulated coal gas mixtures. Sorbent capacity and efficiency deteriorated during the first three cycles, but stabilized thereafter. (2) Sorbent spalling was observed and appeared to increase with sulfur loading. Possible causes of spalling may be attributed to the induced crystal lattice stresses due to the formation of ZnS and especially ZnSO{sub 4}, which have relative molar volumes that are approximately 1-1/2 and 3 times larger, respectively, than that of the original ZnO. (3) Based on these results, it is apparent that the molybdenum-promoted zinc titanate with Zn/Ti molar ratio of 1.91 may not be a suitable sorbent for hot gas desulfurization in the fixed bed reactor for the Pinon Pine project, due to problems with spalling and loss of reactivity during sulfidation/regeneration cycling.
Date: September 1, 1993
Creator: Gasper-Galvin, L. D.; Mei, J. S.; Everitt, C. E. & Katta, S.
Partner: UNT Libraries Government Documents Department

Manganese-based sorbents for coal gas desulfurization

Description: The intent of this study is to perform a preliminary screening on a particular Mn-based sorbent, CST-939 (from Chemetals), for hot gas desulfurization. The purpose of the preliminary screening is to determine which temperature and type of coal gas this sorbent demonstrates the greatest capacity and efficiency for sulfur removal. The following conclusions were made from the data collected on the CST-939 sorbent: The sorbent efficiency and capacity are much greater at 343{degrees}C (650{degrees}F) than at 871{degrees}C (1,600{degrees}F). The sorbent efficiency and capacity are much greater in the presence of the more highly-reducing Shell gas than with the less-reducing KRW gas. The sorbent showed tremendous capacity for sulfur pickup, with actual loadings as high as 21 weight percent. Oxidative regeneration at 871{degrees}C (1,600{degrees}F) appeared to decompose sulfate; however, unusually high SO{sub 2} release during the second sulfidations and/or reductive regenerations indicated incomplete regeneration. The average crush strength of the reacted sorbent did not indicate any loss of strength as compared to the fresh sorbent. Superior sorbent performance was obtained in the presence of simulated Shell gas at 538{degrees}C (1,000{degrees}F).
Date: December 31, 1996
Creator: Gasper-Galvin, L.D.; Fisher, E.P. & Goyette, W.J.
Partner: UNT Libraries Government Documents Department

Hot coal-gas desulfurization with manganese-based sorbents

Description: Manganese based hot-gas-desulfurization sorbents are under investigation for use in Integrated Gasification Combined Cycle advanced electric-power-generation systems. The objective of this project is to develop a regenerable Mn-based pellet formulation that can achieve low sulfur partial pressures, has a high capacity for sulfur and sufficient strength for potential use in fluidized beds, and can be regenerated for many cycles. Fifteen different formulations of manganese sesquioxide, each with either titania or alumina, were prepared and characterized at the University of Minnesota. Each formulation was indurated under conditions sufficient to achieve 1 lb/pellet/mm of diameter crush strength. Sulfidation screening was performed in a thermogravimetric analyzer at 500 to 900 C. A sorbent containing MnCO{sub 3} and TiO{sub 2}, which showed superior crush strength and reactivity, was selected for multi-cycle fixed-bed testing at the Morgantown Energy Technology Center. Four cycles of sulfidation showed that the sorbent had excellent efficiency and capacity for sulfur removal. Good regenerability was achieved with air-steam at 871 C.
Date: August 1, 1996
Creator: Berns, J.; Hepworth, M.T.; Slimane, R.B.; Gasper-Galvin, L.D.; Fisher, E.P. & Venkataraman, V.K.
Partner: UNT Libraries Government Documents Department