Reactivity of styrene with tert-butyl hydroperoxide over cu-based double hydroxide catalysts

Abstract

Copper(II) ions are inserted into brucite-like sheets in the Zn-Cu-Al ternary hydroxides via the precipitation route. The amount of octahedral Cu(II) sites in the Zn-Al(OH) interlayers depends on the copper loadings. The square-planar configuration (CuO) was observed in the high-copper content samples. The Cu-inserted zinc aluminum hydroxides have lamellar structure, modest surface area, and hexagonally uniform plate-like particles. All synthesized hydroxides were tested for the liquid-phase oxidation of styrene. The overall conversion of styrene obtained about 60–80 % and styrene oxide selectivity is about 70 %. The catalytic activity is correlated with the electronic configurations of copper(II) ions and reaction variables. The copper(II) ions in the brucite-like sheets proceeded through the oxidation of styrene following the metal-superpoxo pathway while the extra-lattice copper(II) ions underwent reaction with free radical route. The experimental results also indicated Cu-intercalated layered double hydroxide catalysts are more active than copper(II) oxide in the liquid-phase oxidation of styrene under the same conditions.