Vapor Phase Catalytic Transfer Hydrogenation (CTH) of Levulinic Acid to γ-Valerolactone Over Copper Supported Catalysts Using Formic Acid as Hydrogen Source

Vapor phase catalytic transfer hydrogenation (CTH) of aqueous levulinic acid (LA) with formic acid as hydrogen source over different copper catalysts is reported. The Cu-SiO2 showed the highest LA conversion (56%) and selectivity to gamma-valerolactone (GVL, 87%) at 250 degrees C. Analysis indicates that the presence of acid sites are responsible for the cleavage of C-O bonds forming angelicalactone intermediate followed by its hydrogenation to GVL over copper species. Even though the acid sites are necessary a quantitative correlation between acid sites and LA conversion was not observed. Characterization indicated that the higher conversion over Cu-SiO2 can be related to metal support interaction as evident from higher reduction temperature of copper species in H-2-TPR compared to other catalysts.