Adsorption of nitric oxide and temperature programmed desorption on nonstoichiometric nickel–copper manganites

Abstract

The interaction of nitric oxide with nonstoichiometric nickel–copper manganites has been investigated by adsorption and temperature programmed desorption (TPD) experiments. Nitric oxide was found to adsorb molecularly at room temperature on such oxides. Reversibly and irreversibly adsorbed NO molecules were evidenced. The amount of reversibly and irreversibly adsorbed NO increased with the nickel content but decreased with the copper one. Moreover, the ratio reversible/irreversible increased with the copper content of the oxides. TPD experiments indicated that adsorbed NO desorbs at low temperature (below 200°C) mainly as NO molecules (70–90%). The balance consists of N 2O, a part of which desorbs below 200°C and the rest above 250°C. The area of the peak corresponding to the desorption of nitrous oxide at high temperature is far much larger for copper-free oxides.