Catalyzed decomposition of N2O on metal oxide supports

The catalytic decomposition of N2O using metal oxides supported on silica, magnesium oxide, calcium oxide and hydrotalcite-like supports was studied. CoO is much more active than CuO and Fe2O3 when supported on silica. A conversion of 95% was achieved using CoO on SiO2 at 1500 h(-1) GHSV, 500 degrees C and 50,000 ppm feed N2O. However,the use of higher flow rates resulted in lower conversions. We found that when supporting CoO on MgO, a much more active catalyst is attained. A conversion of 95% was achieved using this catalyst at 40,000 h(-1), 500 degrees C, 100,000 ppm N2O feed. This is a significant improvement over any catalyst currently in the literature. The activity of this catalyst was decreased by calcination at 1000 degrees C. XPS and XRD studies revealed that higher temperature calcination led to an inactive crystalline phase. The active catalyst displayed a less crystalline phase involving the support and the metal oxide. Other oxide combination catalysts were found to be less active than the CoO/MgO catalyst. Based on our findings, a modification of the reactions proposed for N2O decomposition is suggested.