Enhanced performances of N 2O destruction in the presence of CO over the mixed metal oxide catalysts derived from hydrotalcite-type precursors

Abstract

The catalytic destruction of N 2O 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 °C and space velocities were set between 15,000 and 100,000/h. The presence of CO in excess of N 2O in the feed showed a positive effect on the N 2O destruction, leading to a decrease in the operation temperature with respect to direct N 2O decomposition. The N 2O 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 N 2O 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 N 2O decomposition in the presence of CO have been suggested by using the results of experimental and analytical investigations.