Recent Advances in Biochar-based Catalysts: Air Purification and Opportunities for Industrial Upscaling

The preparation of eco-friendly carbon-rich (biochar) materials by thermal pyrolysis of waste biomass has been recognized as one of the most economical and effective strategies for gas purification in recent years. Through control of synthesis and activation methods, the surface features and catalytic sites in biochar can be engineered for diverse heterogeneous catalytic reactions. Nonetheless, its commercial utilization in air pollution control has yet been limited to a large extent because of (i) the shortage of databases related to the actual catalytic performance of biochar and (ii) the complexity involved in industrial upscaling. Herein, the merits and demerits of biomass-to-biochar catalyst conversion are discussed, along with the factors to consider in the synthesis stage for enhancing catalytic activities toward air purification applications. This paper also offers an in-depth evaluation of the techno-economic and environmental aspects of biochar-based catalysts and their catalytic reactions for air pollution control and energy production. Lastly, a contemporary perspective is offered to help develop novel biochar-based catalysts for real-world applications in air purification fields.