Catalytic Effect of Dibenzo‐18‐Crown‐6 Ether Complexes With Group 2 Metal Chlorides on the Kinetics of Ethylbenzene Oxidation

A kinetic model of ethylbenzene oxidation catalyzed by dibenzo‐18‐crown‐6 ether complexes with group 2 metal chlorides (Ca, Sr, Ba) was developed and parameterized using experimental data. Kinetic modeling demonstrated that: 1) an increase in the initial catalyst concentration from 1 to 100 mmol/L leads to a monotonic increase in the rate of ethylbenzene hydroperoxide formation (428 K, 1 atm, volume flow rate of air supply to the reactor of 0.018 m3/h, initial ethylbenzene concentration of 8.17 mol/L, initial concentrations of other species are 0), indicating that the formation of ethylbenzene hydroperoxide prevails over its decomposition; 2) catalysts deactivate within 1 h of the ethylbenzene oxidation process; thus, they are not affect subsequent transformations of ethylbenzene hydroperoxide during propylene epoxidation via the Halcon process; 3) among the dibenzo‐18‐crown‐6 ether complexes with group 2 metal chlorides, the complex with Ca chloride at an initial concentration of 5 mmol/L should be recognized as the best catalyst for industrial use (428 K, 1 atm, volume flow rate of air supply to the reactor of 0.018 m3/h, initial ethylbenzene concentration of 8.17 mol/L, initial concentrations of other species are 0), because it provides the same selectivity as that achieved in non‐catalytic ethylbenzene oxidation (about 80%) and reduces the time to reach 10% ethylbenzene conversion by a factor of three (from 1.5 h in the non‐catalytic process to 0.5 h in the catalytic process).