Advances and Challenges in the Valorization of Bio-Oil: Hydrodeoxygenation Using Carbon-Supported Catalysts

Biomass valorization to produce fuels and platform chemicals is one of the most relevant strategies to change the energetic scenario and the currently unsustainable petrochemical industry. Pyrolysis offers the possibility of integrating biomass-derived oils (bio-oil) into this well-established industry, and the adaptation of already in-use technology, as hydrotreatment units, eases this transition. This new concept of biorefinery could also be improved from an environmental point of view by using carbon-based catalysts produced from biomass waste. In this work, we have reviewed hydrodeoxygenation (HDO) of bio-oil as a key process for the development of these biorefineries. The most relevant results on HDO mechanisms and catalysts are highlighted, with the main focus on activated carbon-supported catalysts. Special attention has been paid to those variables and requirements for a potential industrial implementation, such as the use of raw bio-oil, continuous reactors, and available kinetic models in the literature for reactor design. In addition, a final critical revision has been made with the perspectives, main gaps, and challenges for the integration of bio-oil HDO in a biorefinery.