Modified dolomite in biomass gasification with simultaneous tar reformation and CO2 capture: effect of metal loading

Abstract

The CO2 absorption capacity of calcined dolomite [a (CaMg)O solid solution] doped with iron and nickel transition metals has been investigated in a fixed bed reactor operating at temperature conditions (650°C) at which the sorption process is thermodynamically favoured at ambient pressure. The presence of metals (catalytic sites) between CaO grains (CO2 absorption sites) may improve the potential of dolomite for the simultaneous process of catalytic tar reforming and CO2 capture in biomass gasification, with the aim of developing an effective combined catalyst and sorbent particle. It was found that iron and nickel may be optimised in the substrate reducing critical limitations on CO2 capture capacity. A Sorption Enhanced Reforming test is proposed, at 650°C, for both iron and nickel doped calcined dolomite, using toluene as model tar compound: iron has been found to be not active in such conditions, whereas the 4% Ni/(CaMg)O has been indicated as the most suitable combined catalyst and sorbent particle.