Innovative Pathways for the Valorization of Biomass Gasification Char: A Systematic Review

The thermochemical process of gasification is widely utilized for bioenergy production and is particularly attractive due to its high conversion efficiency. However, a gasification byproduct, known as char, is commonly treated as industrial waste despite its attractive qualities. Indeed, due to its high carbon content (up to 91%) and well-developed porosity (specific surface areas up to 1253 m2 g−1), gasification char could be considered a cost-effective substitute for activated carbon in various applications, such as catalysis and adsorption. However, its properties are highly dependent on the gasification parameters and the initial feedstock selected, and thus a careful characterization of the material is needed to find the most suitable applications. This review can act as a preliminary assessment of the gasification along with the expected char properties, aiding in the selection of the most appropriate valorization pathways. In particular, different application areas, their relation to the gasification process, and the char properties are extensively discussed.