Operando FTIR study of the NH3-SCR reaction over Cu/Al2O3 and Fe/Al2O3 catalysts

Abstract

The aim of this thesis was to perform an operando study of the NH3-SCR reaction using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Mass Spectrometry (MS). The experiments were performed in a Nicolet iS50 FTIR Spectrometer with a Harrick Praying Mantis cell. 3 wt% Cu/Al2O3, 3 wt\% Fe/Al2O3 catalysts and pure m-Al2O3 support were used in the experiments. The MS data was used as a qualitative measurement for comparison with the generated IR data. The FTIR spectra showed that the NO gas seemed to react differently with the surface of the different samples. The NO seemed to be weakly chemisorbed on Cu/Al2O3 and disappeared when NH3 was introduced to the system. On the Fe/Al2O3 catalyst, the NO reacted with the surface to form ferric nitrates that could further react with NH3to form H2O and N2. As for the m-Al2O3 support, the introduction of NO was almost not noticeable in the spectra. The MS data showed a difference in N2 production between the three samples, although it was expected to see even more activity in the Cu and Fe samples than on the support alone. However, the IR results indicated that less reaction products were formed on the support.