Palladium Nanoparticles Supported on a Metal-Organic Framework-Partially Reduced Graphene Oxide Hybrid for the Catalytic Hydrodeoxygenation of Vanillin as a Model for Biofuel Upgrade Reactions

In this work we report a new strategy to enhance the catalytic activity and selectivity in heterogeneous catalysis by using a hybrid support that consists of metal-organic framework (MOF) crystals and partially reduced graphene oxide (PRGO) nanosheets to disperse metal nanoparticle catalysts efficiently. We report the development of a Pd nanocatalyst incorporated within a 3D hierarchical nanocomposite that consists of a Ce-based MOF wrapped with thin PRGO nanosheets, Pd/PRGO/Ce-MOF, as a heterogeneous tandem catalyst for the hydrodeoxygenation of vanillin, a common component in lignin-derived bio-oil, under mild reaction conditions. Our results demonstrate that the PRGO/Ce-MOF hybrid scaffold is an excellent support for Pd nanoparticles for the transformation of vanillin into 2-methoxy-4-methyl phenol, an important high-value phenol compound that can be used directly in the chemical and pharmaceutical industries. The high catalytic performance of the Pd/PRGO/Ce-MOF catalyst is attributed to the unique characteristics of the incorporation of the PRGO support that leads not only to a stable and uniform dispersion of the Pd nanoparticles but also to the presence of acidic active sites that promote the hydrogenolysis reaction.