FTIR study of the effects of sulfur poisons on NO adsorption on supported copper oxide catalysts

Infrared spectra are reported of NO adsorbed on alumina-supported copper (II) nitrate which had been calcined in air and evacuated at 583 K. The resulting surface contained Cu+ cation sites and three types of Cu2+ site. The effects of sulfur dioxide and thiophene modification on NO adsorption have been monitored. Sulfur dioxide and thiophene inhibited the adsorption of NO on Cu+ sites. Sulfur dioxide did not inhibit, and thiophene only partially inhibited, NO adsorption on Cu2+ sites in surface spinel and copper(II) oxide species. Comparisons with corresponding data for CO as a probe adsorbate are discussed in relation to the effects of modifier, adsorbate and surface sites on adsorption behaviour.