Characterisation of Mg/Al hydrotalcite with interlayer palladium complex for catalytic oxidation of toluene Original Research Article

The synthesis, characterisation and catalytic behaviour of palladium compound derived from Mg/Al hydrotalcite were investigated in the toluene total oxidation. The hydrotalcite sample was prepared by co-precipitation of the corresponding chlorides (MgCl2, AlCl3 and H2PdCl4) with boiled fresh water and under N2 atmosphere. Under these conditions, the layered double hydroxide [Mg0.75Al0.25(OH)2]0.25+ PdCl2(OH)20.125−x2− (CO3)x2−·nH2O was formed. Palladium species were inserted as [PdCl2(OH)2]2− complex coming from the partial substitution of Cl with OH. The space interlayer was imposed by CO32− present also as balancing anion. This new hydrotalcite is less stable than classical hydrotalcite Mg/Al without Pd since its destruction took place at a lower temperature. The palladium hydrotalcite calcined at 290 °C exhibited the best catalytic behaviour (activity and selectivity) in the total oxidation of toluene compared with a conventional palladium catalyst.