(335b) Desulfurization / Tar Removal for Gasifier and Biogasifier Effluents with Mixed Rare Earth Oxides

/Al₂O₃ (M is a REO and M₂ is either a third REO or a group VIIB-VIIIB transition metal oxide) materials for two applications: hot gas desulfurization/ tar cracking/ secondary reforming, or nanoparticle-promoted combustion. Potential biomass gasification processes result in high (up to 10%) methane breakthrough and tars. In order to reform the CH₄, and to adjust the CO content by water-gas shift, one must first adsorb the sulfur (mostly H2S) and crack the tars to C1-C2. Some reforming/water-gas shift may also occur. Combining these steps in a single operation is both desirable and crucial to the economics of biomass gasification. REOs such as CeO2 show promise as adsorbents/catalysts in these combined applications; however, at present the necessary stability for long-term operation at temperatures of interest (up to 800°C) is lacking.

Intimate mixtures of REOs function better in these applications than any single (e.g., CeO₂) oxide. The mixture composition is the chief variable affecting hydrothermal stability of the materials. Synthesizing REOs such that only mesopores are present may reduce pore mouth poisoning. We are building upon existing synthetic expertise to prepare and characterize (pore distribution, hydrothermal stability, surface structure, H₂S adsorption capacity, tar cracking activity) these materials at LSU.