X射线光电子能谱
催化作用
化学吸附
化学
氨
氨生产
无机化学
吸附
氮气
选择性催化还原
质谱法
分析化学(期刊)
物理化学
化学工程
有机化学
色谱法
工程类
作者
G. Ertl,Nikki A. Thiele
出处
期刊:Applications of Surface Science
[Elsevier]
日期:1979-07-01
卷期号:3 (1): 99-112
被引量:90
标识
DOI:10.1016/0378-5963(79)90064-3
摘要
The chemical nature and compositions of the surfaces of industrial Fe ammonia catalysts were investigated by means of X-ray photoelectron spectroscopy (XPS). Unreduced catalysts exhibit a strong enrichment of K and Al and only rather small Fe concentrations in the surface region. Treatment in N2 + H2 mixtures (1 atm) at 350–400°C causes complete reduction of iron and a substantial increase of the surface concentration of this element whereas the other cations remain in their oxidized state. The establishment of the synthesis equilibrium was followed by means of a mass spectrometer. Under reaction conditions only relatively small stationary concentrations of atomic nitrogen are present on the surface which supports the conclusion that dissociative chemisorption of nitrogen is the rate-limiting step. After cooling the catalyst to room temperature in the reaction gas mixture in addition NH2 adsorbed to the oxidic components as well as NH and/or NH2 attached to iron were discovered.
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