Insights into the twofold role of Cs doping on deN2O activity of cobalt spinel catalyst—towards rational optimization of the precursor and loading

Abstract

Cobalt spinel catalysts promoted with different cesium loadings from various precursors (Cs2CO3, CsNO3, CH3COOCs, and CsOH) were prepared by incipient wetness impregnation. The catalysts were characterized by XRF, XRD, SEM, XPS and Raman Spectroscopy. The work function studies were used to optimized the surface doping and monitor the retention of surface oxygen. The stability of cesium promoter was evaluated by means of species resolved – thermal alkali desorption method. The catalytic activity of N2O decomposition over the synthesized catalysts was studied by temperature programmed reaction. The role of cesium precursor was evaluated in terms of dispersion and the nature of the counterion. The results show that the most active deN2O catalysts are obtained for cesium carbonate at the narrow loading range of 2–3atoms/nm2 (complete N2O conversion at T<200°C). The twofold promotional effect is discussed in terms of modification of the electronic properties of the spinel catalyst (stimulation of dissociation step: N2O+e=N2+O–) and stability of the surface oxygen species (recombination step: O–=½O2+e).