Atmospheric Pressure Continuous Production of Solketal from the Acid-Catalyzed Reaction of Glycerol with Acetone

Abstract

A continuous-flow process at atmospheric pressure was designed for the conversion of glycerol to solketal, an oxygenated fuel additive, through the acid-catalyzed reaction of glycerol with acetone. Process optimization was performed by checking the influence of different variables on the conversion and selectivity. The variables examined were: residence time (12, 24, 60 and 120 min), catalyst type (Amberlyst-15 and K-10 Montmorillonite), catalyst loading (7, 3, and 1 g), reaction temperature (50, 40 and 30 ºC), molar ratio of the reactants (1:2, 1:5, 1:10, 1:15 and 1:20) and solvent used to homogenize the system (dimethylsulfoxide or dimethylformamide). The highest conversion (92%) was observed with 7.0 g of Amberlyst-15, reaction temperature of 50 °C, molar ratio of glycerol to acetone of 1:20 and dimethylformamide as solvent. In all cases, solketal isomers (five and six-membered ring ketals) were the only product observed. The results of solketal formation of this study, carried out at atmospheric pressure, were similar to other studies with pressures of up to 120 bar. The utilization of higher catalyst loading and molar ratio of reactants compensate the use of atmospheric pressure to achieve high conversion levels and selectivity to the desired product.

Solketal Production from Glycerol Ketalization with Acetone: Catalyst Selection and Thermodynamic and Kinetic Reaction Study

“…This issue has already been addressed in Section in which it was demonstrated that the use of dimethyl sulfoxide negatively affected the maximum reactants conversion. Oliveira et al also demonstrated that a higher glycerol conversion could be obtained when using dimethyl formamide as solvent than when using dimethyl sulfoxide under the same operating conditions (323 K and a 2.0 acetone to glycerol molar ratio). Hence, the use of solvents can simultaneously change the reaction kinetics and thermodynamic equilibrium since it affects the reactant and product concentrations, it modifies the interaction between species (accounted for in this work by the introduction of activity coefficients in the model), and it can change the species reactivity by solvation.…”

Glycerol to Solketal for Fuel Additive: Recent Progress in Heterogeneous Catalysts

“…Overall, the most important properties of solid acid catalysts for the conversion glycerol to solketal production was the Brønsted acidity of solid acids [31]. The conversion of glycerol to solketal with resin catalysts has been carried out [32][33][34][35][36]. Table 3 summarizes the conversion of glycerol to solketal over resin catalysts.…”

Activated Bentonite Nanocomposite for the Synthesis of Solketal from Glycerol in the Liquid Phase

“…In particular, the reaction between glycerol and acetone leads to the formation of 2,2-dimethyl-1,3-dioxolane-4-yl methanol, known as solketal, a novel compound with interesting applications. Furthermore, 2,2-dimethyl-1,3dioxan-5-ol and water are also obtained as byproducts of this reaction (Scheme 1) [9,10]. Oliveira et al reported that solketal improves the octane number and prevents the formation of gum as a fuel additive.…”