CO_2与CO在Ni／Al_2O_3催化剂上的吸附行为

对比研究了不同还原温度下ＣＯ２与ＣＯ在Ｎｉ／Ａｌ２Ｏ３催化剂上的吸附行为。结果表明，在５２３Ｋ、５７３Ｋ、６７３Ｋ和７２３Ｋ还原后形成的Ｎｉ物种均是良好的ＣＯ吸附中心，且随着还原温度的升高，ＣＯ吸附量增大。但当还原温度升高至７７３Ｋ时，催化剂对ＣＯ的吸附能力急剧下降。对ＣＯ２而言，仅当催化剂经５７３Ｋ还原时可获得良好的ＣＯ２活化吸附中心，７７３Ｋ还原时则与ＣＯ的吸附相似，催化剂几乎丧失对ＣＯ２的吸附能力。不同的还原温度，不仅造成催化剂上吸附中心数目的改变，同时催化剂上吸附中心的性质也要发生变化。对ＣＯ２的活化吸附需要与ＣＯ不同的吸附中心。

A comparative study of adsorption of CO and CO_2 on Ni/Al_2O_3

he adsorption of CO and CO2 on Ni/Al2O3 catalyst at different reducing tempera tures is investigated comparatively. It is foundthat the nickel species formed by reducing thecatalyst at 523, 573, 673, and 723K act as favorable adsorption sites for CO, and the adsorbed CO amount increases with the reducingtemperatures. However, the adsorptive capacity of the catalyst for CO drastically decreaseswhen the reducing temperature rises up to773K. Only when reduced at 573K can thecatalyst exhibit better active adsorption capacity for CO2. Reduced at 773K, the catalyst almost loses its adsorbability for CO2. the sameas for CO. Variations of both the amount andcharacter of adsorption sites on the catalystwould occur at different reducing temperatures. The active adsorption sites for CO2 areneeded to be different froth those for CO.