Influence of the nature of the lanthanide element of Ln2CuO4 precursors on the catalytic activity obtained after activation in the CO + NO reaction

Three lanthanide cuprates Ln2CuO4 (Ln=La, Pr and Nd) have been studied in the CO + NO reaction. Under reaction conditions, a reduction of the cuprate was observed, with formation of metallic copper, which constitutes the active species in the reaction. After stabilisation, the resulting activity is lower when La in La2CuO4 is replaced by Pr or Nd. This decrease in activity has been related to a different reducibility of the cuprates, as shown by TPR under H2. When La is substituted by Pr or Nd, a higher temperature of formation of the copper active sites should induce the growth of bigger copper particles, which could be at the origin of the observed difference in activity.