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Etherification of Glycerol by tert-Butyl Alcohol: Kinetic Model

Pico, M. Pilar, Romero, Arturo, Rodríguez, Sergio, Santos, Aurora
Industrial & Engineering Chemistry Research 2012 v.51 no.28 pp. 9500-9509
autoclaves, catalysts, engineering, equations, ethers, glass, glycerol, ion exchange, kinetics, magnetism, mixing, models, solvents, temperature
The catalytic etherification of glycerol with tert-butyl alcohol over a strong acid ion-exchange commercial resin (Amberlyst 15) has been studied. The etherification reactions were carried out in a glass laboratory autoclave reactor with magnetic stirring without solvent at autogenous pressure. Experimental results were obtained at different temperatures (50–80 °C) and using an 8.5 wt % catalyst loading referred to the starting amount of glycerol. Four ethers (two monoethers and two diethers) and isobutylene were identified as the main products of glycerol etherification and tert-butyl alcohol dehydration (secondary reaction), respectively. Two simplified heterogeneus kinetic models are proposed to describe the process performance. The first model lumps the monoethers and diethers into the species M and D, respectively, and includes three reactions and the corresponding kinetic equations. The second model includes all of the species detected and six stoichiometric equations. Kinetic parameters for each kinetic model were estimated by data fitting. Irreversible dehydration of tert-butyl alcohol can be assumed at the operating conditions employed in the present study. Both kinetic models proposed describe the evolution of the system properly, in terms of both the reactant and product distributions with reaction time in the temperature range studied.