Catalytic Role of Pd(II) Ions in Mg–Al Hydrotalcites for the Oxidation of Styrene

Abstract

Pd(II) ions were introduced into Mg0.7Al0.3(OH)2(CO3)0.15·mH2O through the co-precipitation of the corresponding nitrate salts at a constant pH value. The presence of Pd in the brucite-like layers affects an increased surface area and decreased crystal domain of the Mg–Al hydrotalcite catalysts. Pd(II) ions may exist in both intra- and extra- brucite-like layers and exhibit different roles in the oxidation of styrene with t-BuOOH, depending on the amount of palladium. The insertion of Pd(II) into the hydrotalcite lattice has significantly improved the catalyst stability. The highest conversion of styrene is about 80% for the production of styrene oxide and benzaldehyde at low temperatures.