Direct Decomposition of NO into N₂ and O₂ on SrFe_0.7Mg_0.3O₃ Perovskite Oxide.

Abstract

and Ti) at the Fe site in SrFeO3 on NO decomposition activity is investigated. The NO decomposition activity increases in the order of Mg > Sn > Ni > Ce > Zr. The highest N2 yield is achieved with SrFe0.7Mg0.3O3. The NO conversion increases with increasing reaction temperature, and conversion of NO into N2 and O2 at 1123 K is 47% and 23%, respectively. The NO decomposition activity of SrFe 0.7 Mg 0.3 O 3 is strongly improved by loading with a small amount of Pt. The N2 yield increases from 47% to 56% and the light-off temperature of NO decomposition activity decreases by 100 K. The effect of oxygen poisoning on NO decomposition over Pt-loaded SrFe0.7Mg0.3O3 is small. -(IWAKUNI, H.; SHINMYOU, Y.; MATSUMOTO, H.; ISHIHARA*, T.; Bull. Chem.

Perovskites as Substitutes of Noble Metals for Heterogeneous Catalysis: Dream or Reality

“…The reaction order of NO is similar (m ≈ 1) whatever the reaction temperature, indicating that a high partial pressure of NO facilitates NO decomposition in the temperature range of 650−850 °C. In contrast, the oxygen concentration has a negative effect on NO decomposition rate, as reported by Iwakuni et al 589,590 and Ishihara et al 581 The reaction order toward O 2 depends on the temperature, and it increases from n = −0.24 at 650 °C to n = −0.08 at 850 °C. Zhu et al 588 The inhibition effect of oxygen strongly depends on the temperature and material composition.…”

“…Catalyst composition moderately affects the rate dependence to P NO . Cofeeding O 2 and NO also lowered the N 2 yield on Ba 0.8 La 0.2 Mn 0.8 Mg 0.2 O 3 and SrFe 0.7 Mg 0.3 O 3 , with reaction orders to O 2 of −0.18 and −0.12, respectively. Therefore, the oxygen inhibition effect depends on the catalyst composition, the weakest effect being recorded with Pt-loaded SrFe 0.7 Mg 0.3 O 3 .…”

“…The reaction rate increased linearly with the square root of the oxygen partial pressure, suggesting that the apparent reaction order of O 2 could be taken as −0.5. P O2 and P NO dependence on N 2 formation rate was estimated by Iwakuni, , Zhu, Ishihara, and Tofan et al − over different perovskites. An almost constant reaction order to NO (∼1.2–1.3) was obtained for La 0.7 Ba 0.3 Mn 0.8 In 0.2 O 3 , Ba 0.8 La 0.2 Mn 0.8 Mg 0.2 O 3 , and Pt-loaded SrFe 0.7 Mg 0.3 O 3 catalysts .…”

“…P O2 and P NO dependence on N 2 formation rate was estimated by Iwakuni, , Zhu, Ishihara, and Tofan et al − over different perovskites. An almost constant reaction order to NO (∼1.2–1.3) was obtained for La 0.7 Ba 0.3 Mn 0.8 In 0.2 O 3 , Ba 0.8 La 0.2 Mn 0.8 Mg 0.2 O 3 , and Pt-loaded SrFe 0.7 Mg 0.3 O 3 catalysts . Catalyst composition moderately affects the rate dependence to P NO .…”

“…SrFeO 3 was also studied for direct decomposition of NO, and its activity was shown to be strongly affected by the dopant (Sr, Mg) . The highest N 2 yield was achieved on SrFe 0.7 Mg 0.3 O 3 .…”