Adsorption of NH 3 , NO 2 and NO on copper-aluminate catalyst: an ab initio density functional study

Abstract

Copper–aluminate (Cu–Al2O3) with a spinel structure is an important catalyst in the abatement of pollution by nitrogen oxides (NO x ), and its high-temperature phase, CuAl2O4, is considered to be an active component. In general, the Cu2+ ion in CuAl2O4 is believed to act as an active site in the NO x removal process. However, a theoretical description of adsorption on the Cu2+ site is still missing. In this study, the interaction of NH3, NO2 and NO molecules with the Cu2+ present on the CuAl2O4(100) surface has been investigated by using a periodic density functional approach. The results show that the adsorption of all the molecules on the Cu2+ site is energetically favourable, whereas NO is the most strongly bound with the adsorption site. The driving force of the adsorption is interpreted on the basis of charge transfer between the adsorbates and the (100) surface, and key information about the structural and energetic properties is also addressed.