Tar removal from syngas from biomass or coal/biomass gasifiers plays an important role in the overall process. Problems caused by tar buildup downstream, such as pipeline blockage and catalyst deactivation, are eliminated by converting tars to fuel gases. Rare earth oxides (REOs, e.g., Ce/LaOx) mixed with transition metals (e.g., Mn, Fe) were synthesized by templated sol-gel or evaporation induced self assembly methods, or supported on thermally stable alumina. Cleanup reactions were in a range near that of a gasifier (650 - 800�C) to enable better process heat integration, using synthetic syngas mixtures with C10H8 as a tar model compound with/without H2S. Some commercial Ni reforming catalyst formulations were examined comparatively. Select fresh and used catalysts were characterized by BET, TPO, XRD, XANES, EXAFS. We found that reforming is the primary reaction although trace amounts of C3, C6 were observed occasionally. While the water-gas shift activity was similar for most of these catalysts, Fe/Mn supported REOs are superior to Ni-based tar reforming catalysts in the studied temperature range, both in terms of S/carbon resistance and methane reforming activity. Transition metals exist mainly both as dopants into a ceria or mixed REO lattice even under high temperature reducing conditions.

Rare earth/transition metal oxides for tar reforming

247th National Meeting (2014)

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