Catalytic reduction of nitrous oxide with carbon monoxide over calcined Co–Mn–Al hydrotalcite

The N2O catalytic reduction by carbon monoxide over Co–Mn–Al calcined hydrotalcite was studied. The effect of oxygen and that of CO/N2O molar ratio on the rate of N2O decomposition was examined. CO strongly enhanced N2O conversion when O2 was absent in the feed gas. In the presence of oxygen, carbon monoxide acts as a non-selective reductant thereby inhibiting N2O destruction. Continuing excess of CO over N2O without presence of O2 led to a very slow reduction of the catalyst, which caused noticeable N2O conversion decrease with progressing catalyst reduction. The simultaneous reduction of N2O by CO and direct N2O decomposition took place when CO was limiting reactant (CO/N2O < 1) but only at temperatures, at which the direct decomposition is possible without presence of reductant. Simple reduction was observed when reactants ratio was CO/N2O ≥ 1.