Interaction between Nitric Oxide and Copper on Copper Zirconia Sulfated Catalysts

Abstract

The room temperature adsorption and temperature-programmed desorption of NO have been performed on unsulfated and sulfated copper zirconia solids (Cu/SZ). Only CuO clusters are present on Cu/ZrO2 and Cu/SZ prepared by the ligand exchange technique with Cu acetylacetonate in organic medium. The sulfation of zirconia induces a stabilization of the mononitrosyl species, adsorbed on Cu, up to ≈333 K, and a shift of νNO from 1872 to 1910 cm-1, which shows a decrease of the electron density at the copper sites. Moreover, it inhibits the formation of nitrito or nitrato complexes on copper. This behavior shows the strong interaction between copper and sulfate species and can be viewed either by a dilution phenomenon of the CuO surface by migrating sulfate species or by migration of sulfate anions on the CuO surface.