An efficient Pd/carbon-silica-alumina catalyst for the hydrodeoxygenation of bio-oil model compound phenol

Bio-oil is a kind of viable renewable and environmentally sustainable energy, which is obtained from fast pyrolysis of biomass. However, bio-oil is not suitable for direct application due to the high content of oxygen and moisture. The upgrading of bio-oil, especially hydrodeoxygenation of bio-oil is highly demanded but remains a challenge owing to the absence of efficient and stable catalysts. Herein, an amphiphilic Pd/carbon-silica-alumina catalyst could catalytic reactions at the oil/water interface and simultaneously stabilized the oil/water emulsions, which would be highly advantageous in bio-oil upgrading. Significantly, the hydrophilicity and hydrophobicity of the catalyst could be adjusted by changing the input amount of precursor with resols, tetraethyl orthosilicate and aluminum chloride hexahydrate. In the catalytic reaction, phenol was used as a model bio-oil compound, where decalin and water were used to simulate an oil/water mixed bio-oil system. The as prepared amphipathic Pd/MCSA-24 catalyst showed the highest conversion of phenol (98.0%) and highest selectivity for cyclohexane (87.7%) at 200 °C, which presented great potential in further bio-oil upgrading applications.