The esterification reaction mechanism of rosin and glycerol on Fe3O4/MOF-5 with annealing temperatures of room temperature, 300, 500, 700 and 900°C was studied through kinetics and TGA-FTIR analysis. Since the esterification reaction is reversible, chemical equilibrium constants were adopted in the kinetic model and the thermodynamic parameters were calculated. A kinetic model considering the three rate-limiting steps of single reactant adsorption, single product desorption and surface reaction, as well as pseudo-homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Haugen-Watson reaction mechanisms were proposed (LHHW) and adsorption of different components 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 was conducted on 38 possible kinetic models, and it was concluded that the ER model of adsorbed glycerol surface reaction was most consistent with the experimental results, with a correlation coefficient above 0.981 and an F value much higher than the experimental results. Greater than F0.05 value. As the catalyst annealing temperature increases, the activation energy decreases from 103.28 kJ mol−1 to 89.55 kJ mol−1. Furthermore, the results of TGA-FTIR characterization further indicated that this esterification involves the exclusive adsorption of glycerol.
The esterification reaction ester of rosin and alcohol on a heterogeneous catalyst is a typical heterogeneous reaction. Due to the wide application of rosin ester products in the manufacturing fields of food, medicine, printing ink and pressure-sensitive adhesives, it has considerable of industrial value.
Among them, the most widely used and widely used one is rosin glyceryl ester [4]. Rosin is derived from live trees (rosin), pine stumps (wood rosin) and alkali extraction of wood during kraft pulping (tall oil rosin) [4], and is composed of 85%–90% tricyclic phenanthrene resin acid and 10 %–15% neutral compounds [5], [6]. The rapid growth of glycerol as a by-product of biodiesel has led to the need to expand the applications of glycerol in various fields and develop new high-value products [7]. Overall, thousands of papers and patents have been published on rosin ester production and its applications