Biochar-Driven Green Separation and Catalytic Upgrading of Bio-Oil: Mechanisms, Applications, and Future Perspectives

In the realm of renewable energy and environmental sustainability, biochar has emerged as a promising material for addressing the challenges associated with bio-oil processing. Derived from biomass pyrolysis under anoxic conditions, biochar possesses a unique combination of properties, including a highly developed porous structure, a wealth of oxygen-containing surface functional groups, and remarkable chemical stability. These attributes endow biochar with exceptional adsorption capacity and catalytic activity, making it an ideal candidate for the separation and upgrading of bio-oil─a complex liquid mixture of organic compounds, such as acids, aldehydes, ketones, and phenols. This review provides an in-depth analysis of the mechanisms underlying biochar’s adsorptive separation and catalytic conversion of bio-oil, with a particular emphasis on how its microphysical and chemical structures influence these processes. The practical applications of biochar in enhancing bio-oil quality are explored, and the current challenges and future directions in biochar activation technologies and bio-oil purification methods are discussed. By offering valuable insights into the optimization of biomass pyrolysis technologies and the efficient utilization of biomass energy, this review aims to inspire further research and innovation in the field, ultimately contributing to the advancement of sustainable energy solutions.