(587e) Monolithic Catalysts for the Cleanup of Coal Gases

Coal gases contain mainly CO, H2, CO2, moisture, H2S, and other minor contaminants. Hydrogen sulfide in coal gases is required to be removed prior to utilizing coal gases for various purposes such as power generation and hydrogen production. Monolithic catalysts for the development of a single-step sulfur recovery process are used to remove H2S from coal gases in this study. Honeycomb dual-mode monolithic catalysts are formulated by impregnating promising catalytic metal promoters into g-alumina wash-coated monolithic catalyst supports to increase removal of H2S from coal gases and decrease formation of COS. Sulfur dioxide is used as an oxidizer to convert H2S into liquid element sulfur to remove H2S from coal gases. This heterogeneous catalytic reaction has heterogeneous products such as liquid elemental sulfur and steam under an operation condition. Most produced liquid elemental sulfur is attached to porous structure of catalysts, and poison catalysts below the sub dew temperature of elemental sulfur. Monolithic catalysts also are deactivated with carbon deposition, and aluminum sulfate formation in addition to elemental sulfur deposition. An economic method of regenerating cyclically deactivated monolithic catalysts will be developed by vaporizing liquid elemental sulfur loaded on monolithic catalysts, washing deactivated monolithic catalysts with NaOH aqueous solution to remove sulfate from honeycomb monolithic catalysts, and burning off carbon deposited on honeycomb monolithic catalysts. Effects of catalyst age on conversion of H2S to elemental sulfur and formation of COS and various regeneration methods of deactivated catalysts are described in this presentation. Performances of regenerated catalysts are presented in terms of H2S removal and selectivity of COS formation at various reactor operation conditions.