Kinetic verification and Comsol modeling of the Diels-Alder reaction of conjugated pentadiene with maleic anhydride in a continuous flow capillary reactor

Synthesis of 3/4-methyltetrahydrophthalic anhydride was carried out by the Diels-Alder reaction in a continuous flow capillary reactor. The efficient liquid–liquid reaction of pentadiene with molten maleic anhydride provided a theoretical basis for replacing the conventional batch reaction process. Different inner diameter sizes of the channel tubes were adjusted in the range of 0.50 ∼ 2.00 mm to find the optimal size to match the strong exothermic reaction. Under the capillary channel size of 0.8 mm, the conversion rate of C5 and MA reached 100 % when nC5: nMA = 1.08:1 at 65 °C for 8 min. The D-A reaction process is accompanied by the autopolymerization of diolefin in the batch reactor. Our results showed that choosing a continuous flow capillary reactor of appropriate size can directly improve the selectivity of the reaction and the quality of the product. The accurate reaction rate constant and activation energy were obtained by establishing a kinetic model, and the effects of temperature, reaction time and pipe diameter were designed using Comsol software.