Cumene Hydroperoxide-Induced Epoxidation of Styrene Using Cu2O and PbO as Catalysts

Abstract

Styrene oxide (STOX), produced by epoxidation of styrene, is a pivotal building block in perfumery chemical and cosmeceutical industries. Catalytic performances of commercially available cuprous oxide (Cu2O) and lead oxide (PbO) are tested for epoxidation of styrene for selective production of styrene oxide (STOX). Cumene hydroperoxide (CHP) is used as the oxygen-inducing reagent in this study. Parametric study by altering the operating conditions indicates that lower temperature and lesser styrene in the feed aid styrene-based STOX selectivity, whereas there exists no significant effect of the catalyst loading on product selectivity. A maximum of ∼42.5% (∼45% STOX selectivity at ∼95% conversion of styrene) and ∼45% (∼50% STOX selectivity at ∼90% conversion of styrene) product yields have been recorded within 6 h of batch operation for Cu2O and PbO, respectively. Detailed deactivation study shows that the loss of catalyst activity upon reuse can be attributed to the combined effect of leaching of active sites and oxidation of the metal oxide catalyst on account of the oxidative nature of the reaction system. A suitable lumped kinetic model is proposed, which satisfactorily explains the trends in product yield and by/coproduct formation. Kinetic parameters are estimated by nonlinear regression along with a 95% confidence interval. The studies presented in this article can be considered useful for designing a technoeconomically feasible hydroperoxide-based route for the production of STOX as an alternative to the conventional chlorohydrin-based process.