Boric Acid as a Novel Homogeneous Catalyst Coupled with Ru/C for Hydrodeoxygenation of Phenolic Compounds and Raw Lignin Oil

Simple and efficient catalytic routes have been explored to upgrade the raw lignin oil. Though homogeneous catalysis is easy to operate and possesses a high reaction rate, it also suffers from the difficulty of product separation. In this work, we used H3BO3 as a novel homogeneous catalyst coupled with Ru/C to overcome the separation problem and carry out the hydrodeoxygenation (HDO) of phenolic compounds and raw lignin oil. H3BO3 showed an outstanding performance over the liquid organic and mineral acids, with a good catalyst recyclability. Phenolic model compounds including monomers and dimers can be efficiently converted into cycloalkanes with yields close to 100%. Moreover, the raw lignin oil also had a good HDO result by using this bifunctional catalyst (H3BO3 and Ru/C). The content of hydrocarbons increased from 7.9% to 93.1% at 260 °C, which promoted the upgraded lignin oil capable to be used as fuel directly.