High dispersed Ru/SiO2-ZrO2 catalyst prepared by polyol reduction method and its catalytic applications in the hydrodeoxygenation of phenolic compounds and pyrolysis lignin-oil

Metal particle size and metal dispersion significantly influence the catalyst activity, and an efficient catalytic upgrade of bio-oil to high-quality liquid fuel is always difficult. Herein, a high dispersed Ru/SiO2-ZrO2 catalyst was prepared by polyol reduction method, which exhibited a high catalytic activity on hydrodeoxygenation (HDO) of the phenolic compounds and pyrolysis lignin-oil. As a model compound, guaiacol had a conversion of 99.9% and a cyclohexane selectivity of 96.7% at the temperature of 240 degrees C. This polyol Ru/SiO2-ZrO2 catalyst had a good recyclability in the guaiacol HDO. No significant decrease on the catalytic activity was presented after continuous 5 runs, and the conversion kept close to 100% and the selectivity of cyclohexane kept above 88%. Several common phenolic compounds also enabled to be turned into corresponding cycloalkanes efficiently. The high Ru dispersion and the large amount of strong acid sites in the polyol Ru/SiO2-ZrO2 are the main reasons for the good catalytic performances. The synergetic effects between high dispersed metal site and strong acid site lead to a promoted efficiency in the HDO process to form the cycloalkanes. This active catalyst was also applicable to the upgrade of pyrolysis lignin-oil. After reaction, the content of hydrocarbons in the lignin-oil increased from 16.2% to 86.1%, and guaiacols and other oxygenated compounds were almost disappeared. The upgraded lignin-oil has potential to be used as high-quality fuels directly.