Durability studies of limonite ore for catalytic decomposition of phenol as a model biomass tar in a fluidized bed

Highlights: • This system permitted long-term gasification of biomass at low temperature. • Periodic burning in oxygen restored the function of the metal catalyst. • Steam reforming at a controlled steam-to-carbon ratio yielded better results. - Abstract: The development of highly active, durable, tar decomposition catalysts is desirable for practical application of biomass gasification at low temperature. In this study, limonite ore calcinated at 900 °C was used as bed material in a fluidized bed for catalytic decomposition of phenol (biomass tar model) at 650 °C. The limonite showed catalytic activity for the decomposition of phenol to produce combustible gases (H₂ and CO). A long-term durability test of phenol decomposition with O₂ regeneration treatment was conducted for 25 h using the limonite catalyst. The O₂ treatment repeatedly removed the deposited carbon, allowing H₂ and CO to be generated constantly for 25 h. Steam reforming of phenol using the limonite catalyst was also conducted with various steam/carbon ratios (S/C = 0, 0.4, and 0.8), of which S/C = 0.4 was the best for suppressing carbon deposition and producing higher volumes of H₂ and CO gases. Continuous steam reforming for 24 h could be achieved using a limonite catalyst with S/C = 0.4, while maintaining the production of H₂ and CO gases, even though carbon deposition occurred steadily. These results indicated that limonite ore is a promising bed material for use in internally circulating fluidized-bed systems for long-term catalytic decomposition of biomass tar.