Continuous Catalytic Tar Reforming of Biomass Derived Raw Gas with Simultaneous Catalyst Regeneration

Abstract

A novel concept for secondary catalytic tar cleaning with simultaneous regeneration of the catalysts is presented in this work. The process is demonstrated by an initial experiment with producer gas from the Chalmers biomass gasifier using ilmenite (FeTiO3) as catalytic bed material. The tar cleaning system was operated at 800 °C and fed with raw gas from the Chalmers biomass gasifier, in which silica sand was used as bed material and the gasification was performed with steam. The tar content of the gas emerging from the gasifier was roughly 30 gtar/Nm3gas. The experiment showed that the catalyst was continuously regenerated from carbon deposits, and the ilmenite reduced the total amount of tar by 35% at a gas residence time in the bed of 0.4–0.5 s. Branched hydrocarbons and phenols were more or less completely reformed, while there was an increase of stable aromatic rings (benzene, naphthalene). The catalyst showed high activity in water-gas shift reactions, and the H2/CO ratio was shifted from around 0.7 prior to the reactor to almost 3 after the reactor.