Direct decomposition of NO over BaO/Y₂O₃ catalyst

NO direct decomposition on BaO/Y₂O₃ oxide catalyst was investigated and it was found that BaO supported on Y₂O ₃ or Sc₂O₃ is highly active to NO decomposition into N₂. The highest N₂ yield of ca.90% at 1123 K was achieved at 5 mol% BaO supported on Y₂O₃. On this catalyst, NO conversion decreases with increasing oxygen partial pressure, PO2, however reasonably high N₂ yield (ca. 40%) was exhibited under co-feeding of 5% O₂ and PO2 dependence is as small as -0.23. From NO-TPD results, large desorption peak of oxygen was observed around 773 K suggesting that weak adsorption strength of O₂ on BaO/Y ₂O₃ catalyst. In case of NO, large NO desorption peak was also observed around 473 K and so NO adsorption was improved by loading BaO on Y₂O₃. In addition, part of NO desorbs as O₂ and NO, and small amount of N₂ desorbs at 773 K. This suggests that disproportional reaction of NO (3NO = N₂ + NO_3ad or NO = N₂O_ad + NO_2ad) occurred and the surface of the catalyst was covered with nitrogen oxide species. In spite of small surface area of BaO/Y₂O₃ (1.1 m²/g), reasonably high N ₂ yield (ca.30%) is shown at a high space velocity of 40,000 h ^-1.