Hydrodeoxygenation of vanillin over carbon nanotube-supported Ru catalysts assembled at the interfaces of emulsion droplets

•Effective hydrodeoxygenation of vanillin has been realized under mild conditions.•Ru/CNTs function both as recoverable emulsifying agents and efficient catalysts.•The fluorescence image was used to observe directly the dispersion of catalysts.•Simultaneous reaction and separation of the products are achieved in emulsion.•The isolation and purification stages are simplified via phase-transfer catalysis.

Carbon nanotube supported ruthenium catalysts, assembled at the water/oil interfaces, show excellent activity and selectivity for the hydrodeoxygenation of the bio-oil model compound of vanillin under mild conditions (1 MPa, 150 °C). Based on a direct fluorescence image, the Ru/CNT catalysts are mainly distributed on the surface of the emulsion droplets, forming a Pickering emulsion. Simultaneous reaction and separation of the products are achieved in the constructed emulsions, which have great potential in the simplifications of the isolation and purification stages for bio-oil refining.