Behavior of Oxygen Species on the Nickel Oxide Catalyst Surface

概要

論文の詳細を見る
The <SUP>18</SUP>O-oxidation of carbon monoxide was studied on nickel oxide catalysts, and the oxygen exchangeability with the oxide during the reaction was determined. The activities of three oxide samples, obtained under different preparation conditions, were compared. The samples were prepared at 350, 600, and 850°C; they are denoted as NiO-I, NiO-II, and NiO-III respectively. In the case of NiO-I, two kinds of oxygen species, weakly and strongly bound to the surface, were observed. Above 120°C, not only weakly but also strongly bound surface oxygen become reactive; however, the binding energy distribution was quite broad. Similar observations were made in the case of NiO-II, with a similar change above 170°C and with a sharp energy distribution. In contrast, for NiO-III, only a small percentage of the monolayer of the surface oxygen became active and exchangeable below 200°C, but above 250°C about three layers became activated. Models are proposed for the surface state of these oxides on the basis of the behavior of the surface oxygen.
公益社団法人日本化学会の論文