Evaluation of regenerative function and activity of reforming toluene by composite catalyst containing spinel oxide

Abstract

Catalysts that can maintain the activity for a long time are indispensable for the distributed power generation consisting of biomass gasifier and Solid Oxide Fuel Cell (SOFC). This study aims to reveal and develop the regenerative function of composite catalysts containing NiAl2O4 that can be regenerated by reduction and oxidation (Red-Ox) for converting tar from biomass. Regenerative function of composite oxide catalyst containing NiAl2O4 spinel (NAO) and Ru added to NAO (RNAO) by Red-Ox cycles and their activity of autothermal reforming of toluene were examined. Regenerating function of NAO and RNAO were investigated by temperature programmed reduction (TPR) and oxidation at 850 °C repeatedly. After 7th times Red-Ox cycles at 850 °C, though the regenerated amount of Ni in NAO decreased by 70%, that in RNAO was maintained. By Red-Ox of NAO and RNAO, Ni was oxidized to NiO at 350–650 °C and dissolved into γ-Al2O3 to form the NiAl2O4 spinel at above 750 °C. In RNAO, RuO2 particles were more dispersed, decreasing its particle size than the initial, with the Red-Ox cycles, since Ru was dissolved into the Ni particles exsoluted from NiAl2O4. By evaluating the activity of autothermal reforming of toluene, NAO and RNAO showed 1.5–3.0 times higher activity than Pt/γ-Al2O3, due to the highly dispersive active sites unoccupied by CO. Since the active metals can be redispersed by oxidation and reduction at the range from 750 °C to 850 °C, NAO and RNAO would contribute the maintenance free system for reforming tar from biomass gasification.