Conversion of fatty acid methyl ester to epoxy plasticizer by auto-catalyzed in situ formation of performic acid: Kinetic modeling and application of the model

摘要

Fatty acid methyl esters (FAMEs) can be converted to epoxy plasticizer by in situ auto-catalyzed formation of performic acid (PFA) in a bi-phase reaction system. However, mass transfer effect could be neglected in a well-stirred reaction system. A pseudo-homogenous kinetic model was thus developed to describe the kinetics of FAME epoxidation. The decomposition of PFA could not be neglected. All of the observed rate constants could be well correlated with temperature and concentration ratio of formic acid to hydrogen peroxide (r = C-FA/C-HP), indicating that increasing temperature and H+ concentration could promote the reactions. The determined activation energies for PFA synthesis, hydrolysis, decomposition, epoxidation of double bonds and epoxide group ring-opening reactions were 56.4, 54.9, 66.9, 57.1 and 45.0 kJ/mol, respectively. Model predication suggested that the reactions should be performed at moderate temperature (323-333 K) in order to increase the consumption selectivity of PFA and hydrogen peroxide and achieve satisfying reaction rates of epoxidation. The results of this work also have provided a strong support to the mechanism interpretation that the protonation of the neutral PFA is the first step for epoxidation of double bond of FAMEs followed by a similar process to that proposed by "butterfly mechanism". (C) 2020 Elsevier Ltd. All rights reserved.