•The studied quaternary reaction system is water + sec-butyl alcohol + sec-butyl acetate + acetic acid.•The liquid-liquid equilibrium data for this quaternary system were determined at 303.15–333.15 K and atmosphere pressure.•The LLE model was established with consideration of the chemical equilibrium of the reversible reaction.•The measured LLE data were used to correlate the binary interaction parameters of the NRTL and UNIQUAC models.There is a reversible reaction (sec-butyl acetate + water ⇔⇔ sec-butyl alcohol + acetic acid) catalyzed by acetic acid in the quaternary system water + sec-butyl alcohol + sec-butyl acetate + acetic acid. In this work, the liquid-liquid equilibrium (LLE) data for this quaternary system were determined at 303.15–333.15 K at atmosphere pressure. The LLE model of this quaternary reaction system was established with consideration of the chemical equilibrium of the reversible reaction. The measured LLE data were used to correlate the binary interaction parameters of the NRTL and UNIQUAC models. The NRTL model is more suitable than UNIQUAC model for describing the LLE of this quaternary reaction system.

The reaction kinetic of the synthesis of methacrylic anhydride was investigated with a batch stirred-tank reactor at atmospheric pressure using methacrylic acid and acetic anhydride as raw materials. The reactions were conducted at several temperatures between 343.15 and 363.15 K and at various starting reactant compositions. A homogeneous reversible reaction of the second order was described. A batch reactive distillation column was employed to obtain methacrylic anhydride. The influence of feed molar ratio, reflux ratio, and entrainer on the reaction was investigated, and a suitable operating parameter was obtained. Under these conditions, the conversion of methacrylic acid was 99.95%, and the yield of methacrylic anhydride was 86.99%.