Efficient catalytic hydrodeoxygenation of phenolic compounds and bio-oil over highly dispersed Ru/TiO2

Abstract

Upgrading of bio-oils to value-added products through simple and cost-efficient catalytic routes is always a big challenge in the energy utilization field. Herein, we prepared a highly dispersed 2 wt% Ru/TiO2 catalyst using a simple and novel photochemical method at room temperature. The synthetic catalyst exhibited an efficient performance on the HDO of phenolic compounds and real bio-oil, owing to its high Ru dispersion. Guaiacol could be converted into cyclohexane with 91.3% selectivity at 260 °C under 1 MPa H2 atmosphere. Other typical phenolic monomers (phenol, anisole, etc.) and dimers (α-O-4, 4-O-4, etc.) were transformed into cycloalkanes with most yield close to 100%. Results showed that the cleavage of ether bonds and the HDO step can be realized in one pot. This catalytic system was also effective on the upgrade of bio-oil derived from the pyrolysis of cotton straw. A upgraded product composed of 32.4% hydrocarbons and 57.6% alkylphenols was achieved at 280 °C, which can be used as fuels and chemicals respectively. The enhanced reaction temperature (300 °C) enabled hydrocarbon contents increased to 41.4%, leaving the other oxygenated compounds only 4.2%. This work provides a promising reference for the valorization of raw bio-oil.