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.