Showing papers by "Masakazu Iwamoto published in 1978"

Study of Metal Oxide Catalysts by Temperature Programmed Desorption. 3. Formation and Reactivity of Adsorbed Oxygen over α-Ferric Oxide

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...

Activity of copper(II)-exchanged Y-type zeolites in the catalytic decomposition of nitrogen monoxide

Abstract: Among several metal ion-exchanged Y-type zeolites tested, only the copper(II)-exchanged zeolite exhibited appreciable activity for the catalytic decomposition of NO above 450 °C, and was not poisoned by either oxygen or water vapour.