Experimental Study and Model of Reaction Kinetics of Synthesis of Methacrylic Anhydride

Methacrylic anhydride is widely used as the esterification agent. In this paper, the reaction kinetics of synthesis of methacrylic anhydride were investigated in a batch stirred-tank reactor at atmospheric pressure by using methacrylic acid and acetic anhydride as raw materials. The reactions were carried out under several temperatures between 343.15 and 363.15K and various starting reactant compositions. Both the influence of temperature and initial molar ratio of Methacrylic anhydride to acetic anhydride on reaction kinetics were studied in a range that is interesting for process design. Base on the characteristics of the reaction, a typical consecutive reaction mechanism was deduced. Homogeneous reversible kinetic model of second-order was described, and the reaction rate constants and activation energy were obtained according to the experimental reaction rate curves. The kinetic equations for the preparation of methacrylic anhydride from methacrylic acid and acetic anhydride are as follows:

According to these equations, the first reaction is an exothermic reaction and the second reaction is an endothermic reaction. The reaction kinetic model was in good agreement with the experimental data. The biggest relative error was nearly 1.5% in the subsequent reaction process.