Hydrogenation of Biofuels with Formic Acid over a Palladium-Based Ternary Catalyst with Two Types of Active Sites

A composite catalyst including palladium nanoparticles on titania (TiO2) and on nitrogen-modified porous carbon (Pd/TiO2@NC) is synthesized from palladium salts, tetrabutyl titanate, and chitosan. N-2 sorption isotherms show that the catalyst has a high BET surface area (229m(2)g(-1)) and large porosity. XPS and TEM characterization of the catalyst shows that palladium species with different chemical states are well dispersed across the TiO2 and nitrogen-modified porous carbon, respectively. The Pd/TiO2@NC catalyst is very active and shows excellent stability towards hydrogenation of vanillin to 2-methoxy-4-methylphenol using formic acid as hydrogen source. This activity can be attributed to a synergistic effect between the Pd/TiO2 (a catalyst for dehydrogenation of formic acid) and Pd/NC (a catalyst for hydrogenation of vanillin) sites.