Regeneration of deactivated biochar for catalytic tar reforming by partial oxidation: Effect of oxygen concentration and regeneration time

The regeneration of the catalytic activity of deactivated biochar is critical in the reforming of biomass tar. In this paper, the regeneration effects of partial oxidation on biochar's catalytic activity for tar reforming were explored. The catalytic activity of regenerated biochar was verified using a single-stage three sieve plate reaction system. The biochar physicochemical structure was characterised by N₂ adsorption, Raman, FTIR and TG analysis. The tar fraction was analysed by GC–MS and the generation of the gas phase fraction was detected online by a synthetic gas analyzer. The results demonstrate that oxidative regeneration can effectively recover the catalytic activity of biochar and promote the production of CH₄ and H₂. After oxidative regeneration, the external surface area and the microporous area of biochar increase significantly. In addition, the O-containing structures on regenerated biochar become more abundant. The recovery rate of the catalytic activity of RB-0.4-7 is 108.1% and its comprehensive efficiency reaches a maximum of 79.1%. This indicates that the regeneration of deactivated biochar is most efficient when 0.4% oxygen is supplied for 7 min, taking into account the catalytic activity of regenerated biochar and its weight loss rate during the regeneration. The yield of CH₄ and H₂ catalyzed by regenerated biochar is increased compared with SB. Considering the gas generation in catalytic reforming, a regeneration time of 9 min at the oxygen concentration of 0.4% is considered to be the optimum regeneration condition for deactivated biochar.