Hydrogenation of Lactic Acid to 1,2‐Propanediol over Ru‐Based Catalysts

The catalytic hydrogenation of lactic acid to 1,2‐propanediol with supported Ru catalysts in water was investigated. The influence of catalyst support (activated carbon, γ‐Al(2)O(3), SiO(2), TiO(2), and CeO(2)) and promoters (Pd, Au, Mo, Re, Sn) on the catalytic performance was evaluated. Catalytic tests revealed that TiO(2) yields the best Ru catalysts. With a monometallic Ru/TiO(2) catalyst, a 1,2‐propanediol yield of 70 % at 79 % lactic acid conversion was achieved at 130 °C after 20 h reaction. Minor byproducts of the hydrogenation reaction were propionic acid, ethanol, 1‐propanol, and 2‐propanol. For the bimetallic catalysts, the addition of Pd and Au slightly enhanced the performance of Ru/TiO(2), whereas the addition of common hydrogenation promoters such as Re, Mo, and Sn impaired the activity.