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

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 N-2 atmosphere. Under these conditions, the layered double hydroxide [Mg0.75Al0.25(OH)(2)](0.25+) [PdCl2(OH)(2)](0.125)(2-) (CO3)(x)(2-.)nH(2)O 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 degreesC exhibited the best catalytic behaviour (activity and selectivity) in the total oxidation of toluene compared with a conventional palladium catalyst. (C) 2002 Elsevier Science B.V. All rights reserved.