Upgrading phenolic compounds and bio-oil through hydrodeoxygenation using highly dispersed Pt/TiO2 catalyst

Noble metal catalyst has an outstanding catalytic activity on the hydrodeoxygenation (HDO) process, but its high cost limits large-scale application. Herein, we put forward a novel photochemical method to prepare the highly dispersed Pt/TiO2 catalyst with a low metal loading. And it presented an efficient performance on the HDO of phenolic compounds and real bio-oil. Guaiacol could be converted into cyclohexane with 95.1% selectivity at 280 degrees C under 1 MPa H-2 atmosphere. Characterization results revealed that the high Pt dispersion was the critical factor for the high catalytic activity. And the photochemical method preferred to achieve high metal dispersion due to the room temperature condition. Other typical phenolic monomers and dimers were able to transform into hydrocarbons with most yield above 80%, wherein not only the deoxygenation step, but also the cleavage of ether bonds 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. Hydrocarbon content increased to 33.80% from 11.33%. Alkylphenols content increased to 51.38% from 27.86%. These two products can be used as value-added fuels and chemicals, respectively. Guaiacols and syringols were completely converted into alkylphenols and hydrocarbon. The amount of other oxygenated compounds also decreased significantly. This simple and active catalytic system is potential to apply widely for the upgrade of raw bio-oil.