Biochar as a support for nanocatalysts and other reagents: Recent advances and applications

The transformation and use of the biomass are of fundamental energetic and ecological interest. The general objective of this review is to provide an overview of biochar (a major biomass product) as a support for nanocatalysts and other reagents, its mode of coordination and activation with nanoparticles and applications. This includes the physico-chemical characteristics of biochar, the advances in its production processes, and its activation and functionalization in order to improve its physical and chemical characteristics and applications as support in catalysis and environmental decontamination. Biochar is a by-product produced by carbonization of biomass. In this process, the products of interest are syngas and bio-oil, due to their high calorific value and their diverse applications. However, biochar has interesting characteristics. It can be used as support, allowing to disperse nanoparticles of the catalysts, such as those of the transition metals: Fe, Ag, Ni, Pd, etc., bimetallic compositions such as Ru/Re, Fe/Ni, etc. and metal oxides such as Fe3O4, CO3O4, CuO, TiO2, etc., increasing the reactivity of the system, minimizing the leaching of the catalysts and allowing their re-use. These materials can be employed in the degradation of contaminants in aqueous systems, soil and sediments, tar reforming reactions and synthesis of fine chemicals. This review will serve as the basis for new research aiming to add value to this important resource.