Recent advances in the catalytic hydrodeoxygenation of bio-oil

Owing to the increasing interest in alternative energy, there is a focus on bio-oil production from biomass because it is an abundant and renewable energy source. Among the various kinds of biomass conversion technologies, pyrolysis has been investigated widely to produce bio-oil. However, the direct use of bio-oil is difficult because of its poor quality due to the large amounts of oxygen-containing compounds, such as acids, ketones, and esters. Therefore, an additional suitable upgrading process for bio-oil is required. Hydrodeoxygenation (HDO) is considered effective for the deoxygenation of bio-oil. This paper reviews the recent progress in the catalytic HDO of bio-oil. In addition, the effects of the solvent and catalyst applied to the HDO of bio-oil are reviewed intensively together with a discussion of the deactivation behavior of the catalyst during HDO.