Advances in metal/ biochar catalysts for biomass hydro-upgrading: A review

Catalytic hydrogenation of biomass feedstocks into clean fuels and chemicals by heterogeneous catalysis is one of the most important means to realize the utilization of biomass, which has a promising application prospect. This review summarizes the recent advances in the preparation of metal/biochar catalysts and the commonness and individuality of catalytic performance for hydrogenation of biomass via noble metal-based catalyst, non-noble metal-based catalyst and bimetallic catalyst, followed by a discussion of the catalytic mechanism and performance of biomass hydro-upgrading process. Specially, this work details the advantages of biochar as support (such as rich oxygen-containing functional groups, rich pore structure, long catalytic life, etc.), the specific catalytic mode of each active site on the metal/biochar catalyst during the hydro-upgrading process, and the interaction mode between the biochar and the metal. Furthermore, more attention is proposed to the fine control of the structure of the metal/biochar catalysts.