Effect of tin on Ru-B/γ-Al2O3 catalyst for the hydrogenation of ethyl lactate to 1,2-propanediol

Amorphous Ru-B supported on gamma-Al2O3 was prepared by a novel reductant impregnation method for the hydrogenation of ethyl lactate to 1,2-propanediol (PDO). The effects of tin on composition, physicochemical properties, thermal stability and reaction behavior of Ru-B/gamma-Al2O3 catalyst were studied by using in situ XRD, TEM, H-2-TPD, XPS and liquid phase hydrogenation of ethyl lactate. The Ru-B/gamma-Al2O3 catalyst prepared by reductant impregnation showed good activity for hydrogenation of ethyl lactate. Addition of suitable amounts of tin (Sn/Ru atomic ratio of 7%) significantly increased the ethyl lactate conversion and the selectivity to 1,2-PDO; a selectivity to 1,2-PDO of 91.5% was obtained at ethyl lactate conversion of 90.7% under mild reaction conditions. The characterizations showed that addition of tin improved the dispersion and thermal stability of Ru-B significantly. The B/Ru ratio of the catalyst, the electron density of Ru, and the strength of hydrogen adsorption of the catalyst increased with increase of tin content over the range studied. (C) 2004 Elsevier B.V. All rights reserved.