Reaction mechanism investigation on the esterification of rosin with glycerol over annealed Fe3O4/MOF-5 via kinetics and TGA-FTIR analysis

Abstract

Reaction mechanism was investigated on the esterification of rosin with glycerol over annealed Fe3O4/MOF-5 with the annealing temperature of room temperature, 300, 500, 700 and 900 °C via the kinetics and TGA-FTIR analysis. Chemical equilibrium constant was employed in kinetic models due to reversible esterification reaction, and thermodynamic parameters were calculated. Kinetic models that considered three kinds of rate-determining steps of single reactant adsorption, single product desorption and surface reaction as well as the reaction mechanism of pseudo-homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Haugen-Watson (LHHW) and the different adsorption of components were proposed to fit the intrinsic kinetic data obtained by eliminating the effects of external and internal mass transfer resistance. Based on the results of linear regression and nonlinear regression, model discrimination among 38 possible kinetic models lead to the conclusion ER model with the surface reaction of adsorbed glycerol is the best appropriate to experimental results, affording a correlation coefficient above 0.981 and the F values much greater than the F0.05 values. The activation energies reduce with increasing of annealing temperature of the catalyst, from 103.28 to 89.55 kJ mol−1. Furthermore, results from TGA-FTIR characterizations further reveal that this esterification involves the exclusive adsorption of glycerol.