程序升温热脱附法表征SmMnO_3及SmFeO_3的表面

CHARACTERIZATION OF SUREACE OF SmMnO_3 AND SmFeO_3 BY TDS AND TPRS METHOD

本文用程序升温热脱附谱(TDS)及程序升温表面反应谱(TPRS),研究了SmMnO_3及SmFeO_3表面上CO与O_2的吸附与反应。实验表明,在SmMnO_3表面上,室温时就存在能与CO反应生成CO_2的氧物种,而对SmFeO_3来说,在温度为620K以前检测不到能与CO反应生化CO_2的氧物种。当CO与O_2先后吸附于SmMnO_3及SmFeO_3表面,则它们的TPRS都出现CO_2,但两者仍有区别。对SmMnO_2在室温以上的TPRS谱都有两个CO_2脱附峰,而对SmFeO_3则只有在较高温度吸附时才出现CO_2的第二个峰,且第二个峰的峰高在333K与451K间有一个极大值,表明在SmFeO_3上O_2在第二吸附中心的吸附是一个活化吸附过程。

The adsorption and coadsorption of CO and O_2 on perovskite type compounds SmMnO-3 and SmFeO_3 are studied using temperature programmed desorption method. After adsorption of CO only desorption of CO_2 can be detected from SmMnO_3, but not detected from SmFeO_3. After coadsorption, two desorption peaks were found around 350K aud 500K on either compound. On SmFeO_3, however, the height of the second peak depends on adsorption temperature, being negligible for room temperature adsorption and reaching a max. for near 380K, suggesting that some activation is required for adsorption.