Glycerol valorization as biofuel: Thermodynamic and kinetic study of the acetalization of glycerol with acetaldehyde

Abstract

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 Delta H-298 K(0) = -8.77 kJ.mol(-1) and Delta G(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.g(cat)(-1).s(-1)) = 3.13 x 10(9) - 6223/T and K-S,K-W = 1.82 x 10(-3) exp(2361/T). The acetalization of glycerol with acetaldehyde presents an activation energy of 51.7 kJ.mol(-1).