Hydrogenation of levulinic acid with and without external hydrogen over Ni/SBA-15 catalyst

Abstract

A series of Ni/SBA-15 catalysts were prepared by impregnation method for the hydrogenation of levulinic acid (LA) to -valerolactone in a fixed bed reactor at atmospheric pressure. The catalysts were characterized by XRD, TPR, AAS, Pulse chemisorption, SEM-EDAX, TEM, BET Surface area and XPS. The catalyst 30wt% Ni/SBA-15 exhibited excellent catalytic performance (97% yield) at 250 degrees C due to the presence of superior number of active surface Ni species. While 30wt% Ni/SiO2 catalyst showed lower catalytic activity (87% yield) at about similar conversion. The co-feeding of formic acid (FA) and water (impurities) with levulinic acid was also evaluated over 30wt% Ni/SBA-15 which yielded excellent levulinic acid conversion. The noteworthy results were obtained at a molar ratio of FA/LA=5. The constant catalytic activity during 10h experiment with an external H-2 flow has showed the sturdiness of the Ni/SBA-15 catalyst.On the other hand, a slight decrease in conversion as well as yield during the time-on-stream in the absence of external H-2 flow was attributed to the accumulation of carbon species on the catalyst surface.