Development of robust spinel oxide catalysts for efficient gasification of biomass

In fueling biomass to gas containing H 2 and CO via gasification, stable and active Ni catalysts are demanded. Ni/Al 2 O 3 catalyst obtained in reduction of oxide containing NiAl 2 O 4 (NAO) can be regenerated to NiAl 2 O 4 by oxidation in air via reaction of NiO and γ-Al 2 O 3 at temperature > ca. 750 °C. Although NAO has such advantage, weak robustness prevents it from being used in practical situations. In this study, NAO with addition of tetragonal and monoclinic ZrO 2 (NAZO) was fabricated expecting a compatibility for high robustness and activity. Activity of steam reforming hydrocarbons, regenerative functions, crystalline phases, fine structures, and robustness were examined for NAOs and NAZOs with different compositions. Addition of ZrO 2 to NAO is advantageous to elevate toughness sustaining high activity of reforming methane, for it was considered that strong basicity caused by activated oxygen vacancies in ZrO 2 facilitates dry reforming hydrocarbons and transformation of ZrO 2 from tetragonal to monoclinic phase enhances its toughness. Catalyst with a well-balanced composition of Ni, Al, and Zr is promising for high robustness and activity of reforming tar. • ZrO 2 increased toughness of catalyst containing NiAl 2 O 4 (NAO) by twice. • In Ni–Al–Zr oxide (NAZO), ZrO 2 was independent of NiAl 2 O 4 , γ-Al 2 O 3 , and NiO. • Regeneration of NiAl 2 O 4 contained in NAZO occurred by redox at ca. 800 °C. • Addition of ZrO 2 to NAZO sustained reforming tar activity at above ca.600 °C. • NAZO decreased CO 2 /CO ratio in steam reforming methane at above ca.600 °C.