Investigation of potassium doped mixed spinels CuxCo3−xO4 as catalysts for an efficient N2O decomposition in real reaction conditions

Abstract

The influence of copper in the mixed spinel CuxCo3−xO4 on the catalytic activity in N2O decomposition was investigated under ideal and real reaction conditions. A strong dependency of the catalytic activity on the amount of Cu in CuxCo3−xO4 catalysts was observed. Decreasing the amount of Cu increases the catalytic activity. Aiming for improved activity the influence of doping with alkaline (earth) metals was investigated. The use of potassium as dopant allowed a further increase of the catalysts activity. High activity was found for K-Cu0.25Co2.75O4 and full conversion was already reached at 330°C under ideal conditions. The effect of O2, NO and H2O in the gas mixtures on the decomposition of N2O was evaluated. Overall, full N2O decomposition could be reached at temperatures as low as 490°C in realistic reaction conditions. Additionally, stability tests emphasise stable activity for at least 60h. Furthermore, no irreversible deactivation even in the presence of NO, O2 and H2O was found. The catalysts were fully characterised by means of XRD, elemental analysis, TGA, TPR and N2-physisorption. TPD-O2 measurements were performed to investigate the influence of the catalyst composition on oxygen vacancies to elucidate the nature of active sites.