Nitrous oxide decomposition over Co/SBA-15 catalysts: the influence of metal loading, cobalt precursor, and solvent effect

Abstract

The influence of cobalt loading (10–50 wt-%Co), cobalt precursor, and solvent on the physico-chemical and catalytic properties of mesoporous Co/SBA-15 catalysts for the N2O decomposition reaction has been investigated. Catalysts were characterised by N2 adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). For Co/SBA-15 catalysts prepared from Co(II) nitrate, the dispersion decreased and the extent of cobalt reduction increased with cobalt loading. A maximum N2O conversion was found for the sample with ca. 30 wt-% Co loading. At similar cobalt loading (ca. 30 wt-%), a low dispersion and a stronger cobalt–support interaction leading to the formation of low reducible cobalt silicates was observed for Co/SBA-15 samples prepared from acetate precursors as compared to that derived from cobalt(II) nitrate, as evidenced by TPR. The former catalysts showed a low N2O decomposition activity. Moreover, at every Co loadings, the catalysts prepared in water exhibited much higher activities than those prepared in ethanol solvent, which could be related to the low reducibility of cobalt species in the latter catalysts. Finally, at comparable Co loading Co/SBA-15 catalysts (nitrate precursor) were more active than a Co/SiO2 and Co/Al2O3 sample.