Comparative study of Nickel-based perovskite-like mixed oxide catalysts for direct decomposition of NO

Abstract

The mixed oxides LaNiO 3, La 0.1Sr 0.9NiO 3, La 2NiO 4 and LaSrNiO 4 were prepared and used as catalysts for the direct decomposition of NO. The catalysts were characterized by means of XRD, XPS, O 2-TPD, NO-TPD and chemical analysis. By comparing the physico-chemical properties and catalytic activity for NO decomposition, a conclusion could be drawn as follows. The direct decomposition of NO over perovskite and related mixed oxide catalysts follows a redox mechanism. The lower valent metal ions Ni 2+ and disordered oxygen vacancies seem to be the active sites in the redox process. The oxygen vacancy plays an important role favorable for the adsorption and activation of NO molecules on one hand and on the other hand for increasing the mobility of lattice oxygen which is beneficial to the reproduction of active sites. The presence of oxygen vacancies is one of the indispensable factors to give the mixed oxides a steady activity for NO decomposition.