Local Electric Field Effect of TMI (Fe, Co, Cu)-BEA on N2O Direct Dissociation

Zeolite catalyst consists of an infinite network of TO4 tetrahedra (T = Si, Al, etc.) having various physic-chemical properties, among which the electric field effect (EFE) constituting one of the most important properties plays a major role in the heterogeneously catalytic reactions. However, up to now few works have been devoted to establishing the relationship between EFE and related catalytic behavior for the zeolite catalyst. In light of that, the present work systematically investigated the local electric field effect of the transition-metal-ion modified beta zeolites [TMI (Fe, Co, Cu)-BEA] during N2O direct decomposition based on Mulliken charge transfer (CT) analysis, frontier molecular orbital analysis (FMO), and diffuse reflectance infrared Fourier transform spectra (DRIFTS). For the O-2 formation mechanism, the EFEs of TMI-BEA and formed alpha O greatly influenced adsorption and further activation of N2O through the CT, which was quantitatively determined by the FMO gaps between TMI-BEA and N2O. For the NO formation mechanism, the weak EFEs of Fe-BEA and formed alpha O during N2O adsorption through its N end gave a clue of low NO selectivity of Fe-BEA. The EFE investigation of zeolite catalyst facilitates the deeper understanding of the reaction mechanism and clarifies the principle for catalyst design.