Hierarchical pore-trapped and hydrogen-bonded phosphoric acid in Pd-supported zeolite for the efficient aqueous hydrodeoxygenation of lignin derivatives at ambient temperature

Abstract

Developing an efficient and stable catalyst for the aqueous hydrodeoxygenation (HDO) of lignin derivatives at ambient temperature is highly desirable. Here, a novel Pd/PHS catalyst with the hierarchical structure was facilely constructed. Taking HDO of vanillin (VAN, a typical molecule of lignin derivatives) to 2-methoxy-4-methyl phenol (MMP) as a model reaction, >99% VAN conversion and 98.2% MMP yield can be achieved over Pd/PHS at ambient temperature in a water solvent, outperforming the recent works reported in the literature. We found that the hierarchal zeolitic structure could immobilize acidic P species in Pd/PHS via trapping and hydrogen-bonding, and these P species could greatly accelerate the conversion of reaction intermediate, enhancing the yield of MMP product. Pd/PHS also showed excellent activities in HDO of other lignin derivatives. We think this work will provide a new route to guide the design of stable catalyst for the efficient aqueous HDO of lignin derivatives to high value-added chemicals and biofuels at ambient temperature.