FTIR INVESTIGATIONS OF THE ADSORPTION AND DISPROPORTIONATION OF NO ONCU-EXCHANGED SILICOALUMINOPHOSPHATE OF TYPE-34

Novel copper exchanged silicoaluminophosphates of chabazite type catal yst have been prepared. Conventional techniques such as elemental anal ysis, X-ray diffraction, scanning electron microscopy, X-ray photoelec tron spectroscopy, nitrogen sorption capacity (BET) have been employed for the characterization of the materials. X-Ray photoelectron spectr oscopy results identified the presence of both Cu-I and Cu-II species on the catalyst. A detailed FTIR study was carried out on the dispropo rtionation reaction of nitric oxide over the Cu-SAPO-34 catalyst. The spectra indicated the formation of nitrous oxide, mono-and dinitrosyl complexes of Cu-I and of Cu-II and nitrate species. The types of NO si tes on the Cu-SAPO-34 are similar to those seen on other copper exchan ged zeolites, in particular Cu-ZSM-5. Effects of the pressure, tempera ture and evacuation on these nitric oxide species have been studied. T he concentration and distribution of NO complexes varies with the NO p ressure, reaction temperature and evacuation. The adsorption of nitric oxide on the copper exchanged silicoaluminophosphate have been compar ed with the copper exchanged high silica pentasil zeolite catalyst und er identical experimental conditions.