Highly dispersed Pd nanoparticles in situ reduced and stabilized by nitrogen-alkali lignin-doped phenolic nanospheres and their application in vanillin hydrodeoxygenation

Herein, we introduced a nitrogen-alkali lignin-doped phenolic resin (N@AL_nPR) to produce palladium nanoparticles through an in situ reduction of palladium in an aqueous phase, without the need for additional reagents or a reducing atmosphere. The phenolic resin nanospheres and the resulting palladium nanoparticles were extensively characterized. Alkali lignin created a highly conducive environment for nitrogen incorporation, dispersion, reduction, and stabilization of palladium, leading to a distinct catalytic performance of palladium nanoparticles in vanillin hydrodeoxygenation. Under specific conditions of 1 mmol of vanillin, 40 mg of catalyst, 1 MPa H₂, 90 °C, and 3 h, the optimized Pd/N@AL₃₀PR catalyst exhibited a nearly complete conversion of vanillin, 98.9% selectivity toward p-creosol, and good stability for multiple reuses. Consequently, an environmentally friendly lignin-based catalyst was developed and used for the efficient hydrodeoxygenation conversion of lignin-based platform compounds.