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测定了氧在氨氧化催化剂Co_3O_4上于100—400℃下的吸附动力学和室温-600℃的热脱附谱,并与离子探针质谱测定的结果进行了比较。动力学曲线指出氧具有快速和慢速不同类型的吸附,热脱附谱显示有相应的脱附曲线。快速吸附对应于两个脱附峰,峰的极大值温度各为165℃,380—420℃;相应的吸附氧粒子可指定为O_2~-,O~-;脱附活化能分别为13.3千卡/克分子,26.7千卡/克分子。慢速吸附服从Elovich吸附规律,吸附过程可能是快速吸附的氧粒子在催化剂表面上迁移生成O~(2-)并入氧化物表面晶格,脱附温度高于500℃时可由表面晶格中逸出。吸附中心可能是表面Co~(2+)离子。讨论了氧吸附与氨催化氧化反应之间的关系。
The adsorption kinetics of oxygen on Co_3O_4 at 100-400 ℃ and thermal desorption spectra at -600 ℃ were measured. The results were compared with the results of ion probe mass spectrometry. Kinetic curves indicate that oxygen has different types of fast and slow adsorption, thermal desorption spectra showed a corresponding desorption curve. Fast adsorption corresponds to two desorption peaks, the maximum peak temperature of 165 ° C, 380-420 ° C; the corresponding adsorbed oxygen particles can be designated O_2 ~ -, O ~ -; desorption activation energy was 13.3 thousand Card / mole, 26.7 kcal / mole. Slow adsorption follows the Elovich adsorption law. The adsorption process may be that the rapidly adsorbed oxygen particles migrate on the surface of the catalyst to form O 2- (2) incorporated oxide surface lattice. When the desorption temperature is higher than 500 ° C., Escape. The adsorption center may be the surface of Co ~ (2+) ions. The relationship between oxygen adsorption and ammonia catalytic oxidation reaction is discussed.