Reaction pathways of propane and propene conversion in the presence of NO and O2 on Cu/MFI

Abstract

The reaction pathways of propane and propene conversion in the presence of NO and O₂ on Cu/MFI have been studied by steady-state and transient reactivity tests, IR spectroscopy and characterization of the samples after the catalytic tests by means of ¹³C MAS NMR and UV–VIS–NIR diffuse reflectance spectroscopy. It is suggested that using both hydrocarbons the mechanism of transformation relevant for the reduction of NO passes through the formation in the sequence: organoitro, aci-nitro, organic acid and ammonia, amide and nitrile species, with the latter three steps in equilibrium, the position of which depends on the presence of water. The ammonia species is that responsible for the distinctive reaction of NO conversion to N₂ over copper sites. Using the two hydrocarbons, however, species of different molecular weight are obtained, besides the formation of carbonaceous-like oligomers in the case of propene. Two reaction networks are proposed to account for the catalytic data observed in the steady-state and transient reactivity tests.