Achieving controlled vanillin HDO by modulation of oxygen vacancies on the Pd/Nb2O5 surface

The conventional Hydrogenation deoxygenation (HDO) process is accompanied by harsh reaction conditions (high temperature, high hydrogen pressure, and long reaction time), leading to problems such as easy catalyst deactivation and poor product selectivity. Therefore, the design of hydrodeoxygenation catalysts that can achieve controllable reaction paths, directional product selectivity and high reaction efficiency under mild conditions has become the key to the problem. Phenolic resin (RF) formed by resorcinol–formaldehyde condensation reaction was introduced as a carbothermal reducing agent to prepare oxygen defect-rich Pd/Nb 2 O 5 -T-RF catalysts. The concentration of oxygen defects on the catalyst surface was changed by adjusting the calcination temperature, which affected the electronic properties and acid properties of the catalyst surface interface and promoted the C-O bond breaking. At 25 ℃ and 80 min, Pd/Nb 2 O 5 -700-RF obtained 100 % Vanillin (VAN) conversion and 98.0 % 2-methoxy-4-methylphenol (MMP) selectivity, and the catalytic performance was significantly better than that of the catalysts without RF treatment as well as other calcination temperatures. Characterization and experimental results showed that the electron-deficient oxygen defect facilitated the adsorption and activation of vanillin and vanillyl alcohol, while promoting the hydrogen spillover on the catalyst surface and improving the HDO catalytic performance. In addition, the method is universal for reducible transition metal oxides and can be further extended to different metal oxide catalysts and applied to other fields.