Chlorine Influence on Palladium Doped Nickel Catalysts in Levulinic Acid Hydrogenation with Formic Acid as Hydrogen Source

Levulinic acid (LA) is a platform molecule, and its valorization toward biofuel additives like γ-valerolactone or tetrahydrofuran is considered as an important step in planning future biorefinery schemes. In this study, various Ni based catalysts were studied for the LA hydrogenation with formic acid (FA) used as a hydrogen source. Two different ways of catalytic activity improvement are discussed (nickel loading vs addition of dopants). The influence of Ni doping by small amount of noble metals (Pt, Pd, Ru, Rh) showed that Ni-Pd is the most active catalyst. Its high catalytic performance is attributed to the synergic effect between two metals and interaction with chlorine. The effect of chlorine on catalytic performance and properties of the catalysts was evaluated by variety of surface and bulk-sensitive characterization methods. It was shown that addition of chlorine is one of the key factors required for high catalytic performance. Chlorine influences distribution of metals on the surface of the catalyst, their interaction with support and facilitates the formation of small crystallites, which is beneficial for reaching high catalytic activity.