Tailoring interfacial microenvironment of palladium-zeolite catalysts for the efficient low-temperature hydrodeoxygenation of vanillin in water

Graphical Creation of interfacial microenvironment between Pd nanoparticles and acidic sites greatly enhanced the efficiency in the chemoselective hydrodeoxygenation of vanillin to 2-methoxy-4-methylphenol. Efficient low-temperature hydrodeoxygenation (HDO) of lignin derivatives to produce biofuels and high value-added chemicals is still of challenge. Here, we have constructed a high active and stable 0.2 wt.% Pd/MS-HZSM-5(30) catalyst, and 94.7 % yield of 2-methoxy-4-methylphenol (MMP) can be achieved in HDO of vanillin (VAN, a typical platform molecule of lignin derivatives) under milder reaction conditions (60 °C, 5 h, molar ratio of VAN/Pd=1200, water phase), outperforming the most works reported recently. Detailed experimental and mechanistic studies demonstrated that the superior catalytic performance was due to the rapid hydrogenolysis of generated intermediate (vanillyl alcohol, VAL) to MMP proceeded in an interfacial microenvironmental created by Pd NPs and acidic sites in Pd/MS-HZSM-5(30). These new insights will provide potential guidance for the efficient low-temperature production of biofuels and valuable chemicals from lignin derivatives or raw lignin.