Effects of air pollutants on the cerium exchanged high silica zeolite catalyst: a Fourier transform infrared study

The interaction of air pollutants such as nitric oxide (NO) and carbon mono xide (CO) gases on the cerium exchanged ZSM-5 material was studied by FT-IR spectroscopy. Highly crystalline and pure H-ZSM-5 was used for preparing t he cerium exchanged material. The cerium exchanged ZSM-5 material was chara cterised by conventional techniques such as ICP-OES, nitrogen sorption capa city (BET), XRD and XPS. X-ray photoelectron spectroscopy identified the pr esence of both Ce-III and Ce-IV species on the surface of the prepared cata lysts. The in situ interaction of NO and CO on the cerium exchanged ZSM-5 w as studied using an FT-IR Pyrex/quartz cell. The adsorption of NO gas led t o the formation of nitrous oxide, mono- and dinitrosyl complexes of cerium, nitrogen dioxide and nitrate species. The adsorption of CO gas led to the formation of mono-, di- and tricarbonyl complexes of cerium and carbon diox ide and carbonate species. The types of NO and CO sites on the Ce-ZSM-5 cat alyst are similar to those observed on copper exchanged catalysts, in parti cular Cu-SAPO-34 and Cu-ZSM-5. (C) 2001 Elsevier Science B.V. All rights re served.