The kinetic modeling of cumene oxidation taking into account oxygen mass transfer

Abstract

• The rate constants of cumene oxidation reactions at 383 and 393 K were found. • Oxygen dissolution in cumene does not affect the cumene oxidation rate. • Oxygen concentrations were found at which cumene oxidation runs at highest rate. • The oxidation rate is maximum if less than half of the supplied oxygen is consumed. The effect of oxygen volume fraction in the nitrogen–oxygen mixture on the cumene hydroperoxide accumulation rate has been experimentally established in the cumene oxidation. A kinetic model of the cumene oxidation to cumene hydroperoxide has been developed and based on the radical-chain kinetic scheme, given by the reactions of non-radical decomposition of cumene hydroperoxide. As a result of calculating the oxygen mass transfer rate from the nitrogen–oxygen mixture (gas phase) to the reaction mixture (liquid phase), it was shown that the oxygen mass transfer rate does not affect the rate of cumene hydroperoxide accumulation. This fact is confirmed by comparable values of the oxygen amount entering the reactor and the oxygen amount consumed as a result of the reaction. Based on the calculations using kinetic model, it was shown that the cumene oxidation rate is determined by the amount of oxygen supplied to the reactor per unit time, and not by the oxygen volume fraction in the nitrogen–oxygen mixture, on which the driving force of mass transfer depends. In this case, the cumene oxidation runs at a highest rate when the oxygen concentration in the reaction mixture is at least half of the oxygen concentration in reaction mixture, which corresponds to the equilibrium establishment between oxygen concentrations in liquid and gas phases (in the absence of chemical reactions). The concentration limit of this mode was established.