Glycerol Valorization as Biofuel: Thermodynamic and Kinetic Study of the Acetalization of Glycerol with Acetaldehyde

The work reported in this article is a thermodynamic and kinetic study of the acetalization reaction between acetaldehyde and glycerol to produce glycerol ethyl acetal (GEA). A catalyst screening was performed allowing for the choice of Amberlyst-15 wet resin as the most suitable catalyst for this reaction. Through the study of the reaction thermodynamic equilibrium, it was possible to determine the value of the equilibrium constant as a function of temperature, ln(K) = 1.419 + 1055/T, and the corresponding thermodynamic parameters ΔH 298 K 0 = −8.77 kJ·mol–1 and ΔG 298 K 0 = −12.3 kJ·mol–1. Additionally, the standard enthalpy and Gibbs free energy of formation of GEA were also obtained, as −584.4 and −387.0 kJ·mol–1, respectively. The Langmuir–Hinshelwood–Hougen–Watson model considering internal mass-transfer limitations presented the best fitting of the reaction kinetic behavior. The parameters estimated for this model were kc (mol·gcat –1·s–1) = 3.13 × 109 – 6223/T and K S,W = 1.82 × 10–3 exp(2361/T). The acetalization of glycerol with acetaldehyde presents an activation energy of 51.7 kJ·mol–1.