Process Intensification by Using a Helical Capillary Microreactor for a Continuous Flow Synthesis of Peroxypropionic Acid and Its Kinetic Study

Peroxypropionic acid (PPA) is an important organic chemical compound. Due to its versatile oxidizing properties, it is used in the oil, chemical and other industries. In this article, an attempt was made for the production of PPA in a Teflon helical capillary microreactor without and with homogeneous catalyst. The article reports the perhydrolysis of PPA with the effect of various parameters such as concentration of hydrogen peroxide, molar ratio of reactants, radius of curvature of the microreactor, concentration of catalyst and temperature. The reaction is slow, as the PPA equilibrium was found to be reached within 10 min at a temperature of 50 degrees C and at 10 mol % catalyst loading based on propionic acid. The reaction was carried out in 13.25 and 23.25 mm radius of curvature of the microreactor in which 4.0375 and 3.488 mol/L concentrations of PPA respectively were obtained at 50 degrees C and 10 mol % catalyst. It indicates that as radius of curvature decreases, better mixing was provided among the reactants for the reaction to give enhanced yield and selectivity. From the experimental data and the kinetic expressions, the expressions of activation energies and reaction rate constants were determined. For PPA synthesis and hydrolysis, the activation energies were 43.897 and 20.658 kJ/mol respectively without catalyst, while the activation energies for both the cases were 42.314 and 17.514 kJ/mol respectively with catalyst of 10 mol% based on propionic acid. The dean number, curve tube friction factor and pressure drop also determined for the helical capillary microreactor.