Catalytic decomposition of nitrous oxide on “in situ” generated thermally calcined hydrotalcites

Abstract

Catalytic decomposition of nitrous oxide to nitrogen and oxygen has been carried out on “in situ” generated thermally calcined hydrotalcites of the general formula M---Al---CO3---HT, where M stand for Ni, Co and Cu, in the temperature range 140–310°C at 50 Torr (1 Torr=133.3 Pa) initial pressure of the gas. All the catalysts showed first-order dependence on nitrous oxide without any inhibition by oxygen. Among the catalysts studied, Ni---Al---CO3---HT was the most active, followed by the cobalt and copper catalysts. These catalysts are more active in comparison with earlier reported Cu-ZSM-5, Co-ZSM-5 and Rh-ZSM-5 catalysts based on their conversion for the decomposition. The enhanced activity can be attributed to non-stoichiometry and dispersion of the active mixed metal oxides. Prior to the kinetic runs, the catalytic precursors were characterised by X-ray diffraction, thermogravimetry-differential scanning calorimetry measurements, IR, transmission electron microscopy and nitrogen adsorption measurements.