文摘
The substituted metal ions in the hexaaluminate structure are regarded as active centers, but their very limited substituted content prevents the obtainment of higher activity. Fe-substituted hexaaluminates exceptionally overcome such a limit. In this paper, we have studied the Fe crystallographic sites in BaFexAl12鈥?i>xO19 (x = 1鈥?2) and proposed the unique mechanism of stabilization of Fe ions in hexaaluminate structure at a high substitution level by employment of Rietveld refinement and 57Fe M枚ssbauer spectroscopy. When x = 1鈥?, the site occupancy of Fe3+ in both 尾I-Al2O3 and newly formed magnetoplumbite phases was kept constant, and the increased Fe3+ ions were accommodated by the increased amount of magnetoplumbite phase. When x = 5鈥?2, the site occupancy of Fe3+ in the magnetoplumbite phase continuously increased, and thus the increased Fe3+ ions were accommodated by the magnetoplumbite structure. BaFexAl12鈥?i>xO19 catalysts exhibited different N2O decomposition properties under conventional furnace heating and microwave heating modes.