Synthesis of ethyl levulinate as fuel additives using heterogeneous solid superacidic catalysts: Efficacy and kinetic modeling

Esters of levulinic acid, which is biomass derived, are used as oxygenated additives in fuels, flavoring and fragrance industry or as blending components in biodiesel. A series of sulphated metal oxide catalysts were prepared and their activities were tested in the synthesis of ethyl levulinate as the model compound, among which UDCaT-5 (mesoporous super acidic zirconia modified catalyst) was the most active and robust catalyst. The effects of various parameters were studied in a batch reactor to establish kinetics and mechanism of reaction under optimized conditions. The reaction follows Langmuir-Hinshelwood-HougenWatson mechanism involving weak adsorption of the reactants and products. The apparent energy of activation was found to be 9.00 kcal/mol for ethyl levulinate. Several other alkyl levulinates were produced from esterification of levulinic acid with different alcohols using UDCaT-5. The use of solid acid catalyst made the process environmentally benign. The catalyst was reused up to four runs including the fresh one. A green and effective route for conversion of biobased levulinic acid into valuable esters is established. (C) 2014 Elsevier B.V. All rights reserved.