La/Zn Bimetallic Oxide Catalyst for Epoxidation of Styrene by Cumene Hydroperoxide: Kinetics and Reaction Engineering Aspects

Styrene oxide (STOX) is mostly produced by chlorohydrin process that generates large amount of waste. A greener alternative to the chlorohydrin process is epoxidation of styrene induced by hydroperoxides. In this work, we have studied this reaction using cumene hydroperoxide (CHP) as oxygen inducing reagent under the influence of the prepared La-Zn bimetallic oxides, which offered reasonably high catalytic activity in terms of conversion and high selectivity for styrene oxide. The side reactions can be suppressed by a proper choice of reaction conditions and mode of reaction. At a given reactant conversion, semibatch modes of operation exhibits higher styrene and CHP-based product selectivity when compared with its batch counterpart. Parametric studies are performed to examine the effects of temperature (ambient temperature 363 K), catalyst loading (0.25-1%), CHP-to-styrene mole ratio (similar to 1-3.5), presence of nonreacting solvent, and surface basicity of catalysts. Catalyst deactivation was studied in detail and a plausible way to regenerate the spent catalyst has been advocated. A suitable kinetic model is proposed that explains the trends in product yield, byproduct formation, and catalyst deactivation. Parameters are estimated by nonlinear regression along with 95% confidence interval calculated by bootstrapping technique.