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

Abstract

The interaction of air pollutants such as nitric oxide (NO) and carbon monoxide (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 the cerium exchanged material. The cerium exchanged ZSM-5 material was characterised by conventional techniques such as ICP-OES, nitrogen sorption capacity (BET), XRD and XPS. X-ray photoelectron spectroscopy identified the presence of both Ce III and Ce IV species on the surface of the prepared catalysts. The in situ interaction of NO and CO on the cerium exchanged ZSM-5 was studied using an FT-IR Pyrex/quartz cell. The adsorption of NO gas led to 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 dioxide and carbonate species. The types of NO and CO sites on the Ce-ZSM-5 catalyst are similar to those observed on copper exchanged catalysts, in particular Cu-SAPO-34 and Cu-ZSM-5.