Oxygen defects in reduced ceria are the catalytic sites for the NO reduction into N₂ in the Toyota Di-Air DeNO_x abatement technology. Traces of NO (several hundred ppm) have to compete with the excess amount of other oxidants, e.g., 5% CO₂ and 5% O₂, in an exhaust gas of a lean burn (diesel) engine. The reactivities of CO₂ and NO over a reduced ceria and noble metal loaded reduced ceria have been investigated under ultra-high vacuum system in TAP and under atmosphere pressure in in-situ Raman and flow reactor set-up. The results showed that CO₂ was a mild oxidant which was able to oxidise the oxygen defects, but hardly oxidised deposited carbon over both ceria and noble metal loaded ceria. NO was a stronger oxidant and more efficient in refilling the oxygen defects and able to convert the deposited carbon, which acted as buffer reductant to extend the NO reduction time interval. NO was selectively and completely converted into N₂. The presence of excess CO₂ hardly affected the NO reduction process into N₂.

中文翻译：

---

还原的二氧化铈基催化剂对CO ₂对NO还原为N ₂的影响

还原的二氧化铈中的氧缺陷是丰田Di-Air DeNO _x减排技术中将NO还原为N ₂的催化部位。在稀薄燃烧（柴油）发动机的废气中，痕量的NO（数百ppm）必须与过量的其他氧化剂（例如5％CO ₂和5％O ₂）竞争。在超高真空系统中，在TAP中，在大气压下，在原位拉曼和流动反应器装置中，研究了还原的二氧化铈和负载有贵金属的还原的二氧化铈对CO ₂和NO的反应活性。结果表明，CO ₂是一种温和的氧化剂，能够氧化氧缺陷，但几乎不氧化在二氧化铈和负载有贵金属的二氧化铈上沉积的碳。NO是一种更强的氧化剂，在补充氧缺陷方面更有效，并且能够转化沉积的碳，而碳作为缓冲还原剂可以延长NO还原的时间间隔。NO被选择性地完全转化为N ₂。过量CO ₂的存在几乎不影响NO还原成N _2的过程。