Enhanced performances of N2O destruction in the presence of CO over the mixed metal oxide catalysts derived from hydrotalcite-type precursors

The catalytic destruction of N2O in the presence of CO has been performed over a fixed bed of mixed metal oxide catalysts derived by calcination from hydrotalcite-type precursors. The hydrotalcite-type precursors were obtained by co-precipitation of cobalt, aluminum and some of the transition metal nitrates such as rhodium, palladium and cerium with the addition of the precipitants under controlled pH. The reactions were carried out under atmospheric pressure in the temperature range of 150-500 degrees C and space velocities were set between 15,000 and 100,000/h. The presence of CO in excess of N2O in the feed showed a positive effect on the N2O destruction, leading to a decrease in the operation temperature with respect to direct N2O decomposition. The N2O destruction rates in the presence of CO were increased hundreds to thousands times than the rates in the absence of CO. The presence of NO in a small amount in the feed did not show any inhibition effect on the N2O conversion in the presence of CO, but do show in the absence of CO. Some mechanistic aspects of the adsorption and the relevant reaction steps concerning the N2O decomposition in the presence of CO have been suggested by using the results of experimental and analytical investigations. (c) 2006 Elsevier B.V. All rights reserved.