Showing papers by "Masakazu Iwamoto published in 1979"
TL;DR: In this article, a temperature-programmed desorption (TPD) technique was used to investigate the formation and reactivity of oxygen adsorbates on the surface of α-Fe2O3 by means of a TPD technique.
Abstract: Formation and reactivity of oxygen adsorbates on the surface of α-Fe2O3 were investigated in the temperature range 0–600 °C by means of a temperature programmed desorption (TPD) technique. At least four different states of adsorbed oxygen were indicated by four TPD peaks, the maxima of which appeared at 50–300 (α), 350–360 (β), 480–490 (γ), and >600 °C (δ), respectively. Mode of preparation hardly affected the essential nature of oxygen adsorption (or desorption) except the relative amounts of respective desorptions. Of these adsorbates, α, whose desorption peak shifts over a wide temperature range depending upon adsorption conditions, was interpreted to be molecular oxygen (O2 or O2−) bonded to the oxide surface with an extraordinarily broad heterogeneity, while β and γ species were tentatively assigned to O2− and O−, respectively, adsorbed on different sites. The activation energies of desorption were 23.8 and 54.6 kcal/mol for β and γ, respectively. On exposure to gaseous hydrogen, β species as well as...
6 citations
TL;DR: In this paper, the reaction of Ag2O with NO has been studied in the range 333-473 K with flow and batch reactors, and the reaction products are Ag[NO2], Ag[ NO3], Ag, and NO2.
Abstract: The reaction of Ag2O with NO has been studied in the range 333–473 K with flow and batch reactors. The reaction products are Ag[NO2], Ag[NO3], Ag, and NO2. A change in the products with reaction times reveals that [AgNO2] is the primary product by reaction (i), Ag2O + NO → Ag[NO2]+ Ag, and then decomposes to Ag[NO3] with the evolution of NO by reaction (ii), 2 Ag[NO2]→ Ag[NO3]+ Ag + NO. When Ag[NO2] is a starting material, reaction (iii), Ag[NO2]→ Ag + NO2, occurs together with (ii). Reaction (i) occurs mainly at ⩽353 K and the reaction order with respect to [NO] is close to unity. Reactions (ii) and (iii) proceed at 353 K and are inhibited by NO. At 453 K in the flow system, Ag[NO3] reacts further with NO through (iv), Ag[NO3]+ NO → Ag + 2NO2. In the static system, on the other hand, (iv) does not proceed. This difference is suggested to result from NO2 inhibition of reaction (iv).
2 citations
TL;DR: In this paper, the reaction of Ag2O with NO has been studied in the range 333-473 K with flow and batch reactors, and the reaction products are Ag[NO2], Ag[ NO3], Ag, and NO2.
Abstract: The reaction of Ag2O with NO has been studied in the range 333–473 K with flow and batch reactors. The reaction products are Ag[NO2], Ag[NO3], Ag, and NO2. A change in the products with reaction times reveals that [AgNO2] is the primary product by reaction (i), Ag2O + NO → Ag[NO2]+ Ag, and then decomposes to Ag[NO3] with the evolution of NO by reaction (ii), 2 Ag[NO2]→ Ag[NO3]+ Ag + NO. When Ag[NO2] is a starting material, reaction (iii), Ag[NO2]→ Ag + NO2, occurs together with (ii). Reaction (i) occurs mainly at ⩽353 K and the reaction order with respect to [NO] is close to unity. Reactions (ii) and (iii) proceed at 353 K and are inhibited by NO. At 453 K in the flow system, Ag[NO3] reacts further with NO through (iv), Ag[NO3]+ NO → Ag + 2NO2. In the static system, on the other hand, (iv) does not proceed. This difference is suggested to result from NO2 inhibition of reaction (iv).