摘要
利用ＴＰＩＲ动态方法研究了Ｒｈ２Ｃｏ２／Ａｌ２Ｏ３上ＣＯ吸附态的动态行为和ＣＯ歧化反应．结果表明，在ＣＯ吸附ＴＰＤ（真空中）ＩＲ动态过程中，Ｒｈ上的孪生ＣＯ谱带强度逐渐同步减弱，Ｃｏ上的线式ＣＯ谱带和Ｒｈ上的桥式ＣＯ谱带强度逐渐减弱的同时向低频位移．完全脱附的顺序为：桥式（１５０℃），孪生（３５０℃）和Ｃｏ上的线式（４００℃）．该结果明显不同于Ｒｈ４／Ａｌ２Ｏ３上相同动态过程的结果，表明ＲｈＣｏ相互作用导致各吸附中心上ＣＯ吸附强度的改变．在ＣＯ吸附ＴＰ（ＣＯ中）ＩＲ动态过程中，三种吸附的ＣＯ谱带２５０℃以上才发生强度减弱直到消失．表明ＣＯ歧化在２５０℃以上才发生．并且Ｒｈ上桥式中心上的歧化速率与孪生中心上相等，Ｃｏ上的线式中心上的ＣＯ歧化速率则大于Ｒｈ４／Ａｌ２Ｏ３的Ｒｈ线式中心．
Dynamic behavior of chemisorbed CO and CO disproportionation have been investigated by using TPIR dynamic method. The results indicate that the bands of gemdicarbonyl CO gradually decreased in intensity and the band of linear CO on Co as well as the band of bridged CO on Rh decreased in intensity with a simultaneous shift to lower frequency during TPD (in vacuum) dynamic process on Rh2Co2/Al2O3. Fully desorbed order is bridged CO (150℃), gemdicarbonyl CO (350℃) and linear CO (400℃) on Co which is considerably different from the results obtained on Rh4/Al2O3 indicating that the interaction of RhCo altered CO adsorption strength on Rh sites and Co sites over Rh2Co2/Al2O3. The results obtained from TP (in CO) dynamic process indicate that CO disproportionation took place above 250℃, the rate of CO disproportionation on bridged sites of Rh is identical to that on gemdicarbonyl sites, and the rate of CO disproportionation on Co linear sites over Rh2Co2/Al2O3 is higher than that on Rh linear sites over Rh4/Al2O3.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
1997年第6期454-458,共5页
基金
国家自然科学基金
中国科学院大连化学物理研究所催化基础国家重点实验室基金
关键词
铑
钴
双金属催化剂
一氧化碳
吸附
Rhodium, Cobalt, Bimetallic catalyst, Carbon monoxide, Chemisorption
