Vapor phase hydrogenation of aqueous levulinic acid over hydroxyapatite supported metal (M=Pd, Pt, Ru, Cu, Ni) catalysts.

Ca5(PO4)3(OH) (HAP) supported metal (Ru, Pt, Pd, Cu and Ni) catalysts were examined for vapour phase hydrogenation of aqueous levulinic acid (LA). Ru/HAP demonstrated higher TOF of -valerolactone (gVL) over the other metal catalysts. The LA dehydration products such as angelica lactones (both - and -AL) were formed significantly over Pt, Pd, Ni and Cu/HAP catalysts. Influence of Bronsted and Lewis acid sites was exemplified by pyridine adsorbed FT-IR studies on Ru/HAP that exhibited very weak band due to Bronsted sites at 1552 cm-1 and a strong band at 1450 cm-1 attributed to Lewis acid sites. Ru supported on SO4 2- HAP demonstrated selective dehydration of LA to -angelica lactone. Hydrogenation activity of Ru was diminished while supported on SO4 2- -HAP, quite contrast to this the fresh HAP behaved as a selective support for Ru towards GVL formation. Thus, HAP has been identified as suitable support for Ru in the conversion of LA at ambient pressure