Reactive bed materials for improved biomass gasification in a circulating fluidised bed reactor

Reactive bed materials for the optimisation of the biomass gasification in a fast internally circulating fluidised bed (FICB) reactor system were tested under sulphur-free (S-free) and H 2 S enriched conditions in a micro-scale fluidised bed reactor. In the experiments, the bed materials (natural olivine, ( Fe x Mg 1 - x ) 2 SiO 4 , perovskite-type oxides, Ba 0.3 Sr 0.7 Fe 0.9 Mn 0.1 O 3 - δ and La 0.65 Sr 0.35 Cr 0.5 Mn 0.5 O 3 - δ , Gd 0.1 Ce 0.9 O 2 and a natural calcite, CaCO 3 ) were examined under realistic redox-cycling conditions to study their oxygen capacity and release, their catalytic activity towards toluene reforming as well as their mechanical and chemical stability. It was found that the synthesised materials outperform the natural materials as reactive bed materials for the FICFB process under S-free atmosphere. Gd 0.1 Ce 0.9 O 2 has better catalytic properties, perovskites show a higher oxygen storage capacity. However, in the presence of H 2 S , the perovskite loose their oxygen capacity, while calcite can form a sulphide/sulphate cycle which allows for significant oxygen capacity. Additionally, the catalytic activity goes up. Therefore, under real conditions, the two natural materials, calcite and to a lower extent olivine, have clear advantages with respect to price, catalytic activity and oxygen capacity.