| Summary: | The effect of calcination temperature (500–700 <inline-formula><math display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula>C) on physico-chemical properties and catalytic activity of 2 wt. % K/Co-Mn-Al mixed oxide for N<sub>2</sub>O decomposition was investigated. Catalysts were characterized by inductively coupled plasma spectroscopy (ICP), X-ray powder diffraction (XRD), temperature-programmed reduction by hydrogen (TPR-H<sub>2</sub>), temperature-programmed desorption of CO<sub>2</sub> (TPD-CO<sub>2</sub>), temperature-programmed desorption of NO (TPD-NO), X-ray photoelectron spectrometry (XPS) and N<sub>2</sub> physisorption. It was found that the increase in calcination temperature caused gradual crystallization of Co-Mn-Al mixed oxide, which manifested itself in the decrease in Co<sup>2+</sup>/Co<sup>3+</sup> and Mn<sup>3+</sup>/Mn<sup>4+</sup> surface molar ratio, the increase in mean crystallite size leading to lowering of specific surface area and poorer reducibility. Higher surface K content normalized per unit surface led to the increase in surface basicity and adsorbed NO per unit surface. The effect of calcination temperature on catalytic activity was significant mainly in the presence of NO<sub>x</sub>, as the optimal calcination temperature of 500 <inline-formula><math display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula>C is necessary to ensure sufficient low surface basicity, leading to the highest catalytic activity. Observed NO inhibition was caused by the formation of surface mononitrosyl species bonded to tetrahedral metal sites or nitrite species, which are stable at reaction temperatures up to 450 <inline-formula><math display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula>C and block active sites for N<sub>2</sub>O decomposition.
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