H4SiW12O40-Catalyzed Levulinic Acid Esterification at Room Temperature for Production of Fuel Bioadditives

Abstract

In this work, a route to synthesize bioadditives through H4SiW12O40-catalyzed levulinic acid esterification reactions with alcohols of short chain at room temperature was assessed. Among the Bronsted acids assessed (i.e., sulfuric, p-toluenesulfonic, silicotungstic, phosphomolybdic and phosphotungstic acids), H4SiW12O40 was the most active and selective catalyst. High conversions (ca. 90%) and selectivity (90–97%) for alkyl levulinates with carbon chain size ranging from C6 to C10 were obtained. The effect of main reaction parameters was studied, with a special focus on the reaction temperature, stoichiometry of reactants, concentration and nature of the catalyst. Insights on reaction mechanism were done and the activity of heteropoly catalysts was discussed based on acid strength and softness of the heteropolyanions. The use of renewable raw material, the mild reaction conditions (i.e., room temperature), and a recyclable solid catalyst are the some of the positive features of this process. The alkyl levulinates obtained are renewable origin bioadditives that can be blended either to gasoline or diesel.