CO吸附微量量热法研究γ-Al_2O_3负载贵金属催化剂  

MICROCALORIMETRIC STUDIES OF CO ADSORPTION ON γ Al 2O 3 SUPPORTED PRECIOUS METAL CATALYSTS

作　　者：贾继飞[1,2] 沈俭一[1,2] 徐竹生[1,2] 张涛[1,2] 屠迈 林励吾[1,2] 

机构地区：[1]中国科学院大连化学物理研究所 [2]南京大学化学系

出　　处：《催化学报》1997年第5期359-363,共5页

基　　金：福特-中国研究与发展基金;国家教委跨世纪人才基金

摘　　要：用ＣＯ吸附微量量热法系统地研究了γＡｌ２Ｏ３负载的Ｐｔ，Ｐｄ，Ｒｈ及ＰｔＳｎ，ＰｔＦｅ等贵金属催化剂．结果表明，Ｐｔ／γＡｌ２Ｏ３，Ｐｄ／γＡｌ２Ｏ３，Ｒｈ／γＡｌ２Ｏ３贵金属催化剂上ＣＯ的微分吸附热对覆盖度的函数非常相似，其初始微分吸附热均约为１２０ｋＪ／ｍｏｌ．随着ＣＯ覆盖度的增加，ＣＯ的微分吸附热逐渐降低．Ｐｔ／γＡｌ２Ｏ３催化剂上ＣＯ吸附位数目对ＣＯ微分吸附热不同区间的分布非常不均匀，大部分都集中在１００ｋＪ／ｍｏｌ以上．Ｓｎ，Ｆｅ引入Ｐｔ／γＡｌ２Ｏ３催化剂后对ＣＯ的初始微分吸附热影响不大，随着Ｓｎ，Ｆｅ含量的增加，ＣＯ较强吸附位的数目逐渐减少，表明Ｐｔ，Ｓｎ（Ｆｅ）与γＡｌ２Ｏ３载体之间存在相互作用．络合法制备的ＰｔＳｎ／γＡｌ２Ｏ３（ｃ）催化剂上ＣＯ的微分吸附热分布区间非常宽（４０～１１０ｋＪ／ｍｏｌ），且在分布区间非常均匀．CO adsorption microcalorimetry is employed to study γ Al 2O 3 supported precious metal (such as Pt, Pd, Rh, Pt Sn, Pt Fe) catalysts. The results indicate that the plots of differential heat versus CO coverage are very similar for Pt/ γ Al 2O 3, Pd/ γ Al 2O 3 and Rh/ γ Al 2O 3. Their initial differential heat is about 120 kJ/mol. As CO coverage increase, the differential heat of CO adsorption decreases owing to its adsorption on weaker sites and/or interaction between adsorbed species. At higher coverage, the significant decrease in differential heat of CO adsorption indicates saturation of the surface. The differential heat of CO adsorption on Pt/ γ Al 2O 3 is mainly over 100 kJ/mol. Adding Sn or Fe to Pt/ γ Al 2O 3 has no significant effect on the initial differential heat. The amount of stronger CO adsorption sites decreases when increasing Sn or Fe content, indicating there is an interaction between Pt, Sn(Fe) and support ( γ Al 2O 3). The main distribution of differential heat of CO adsorption on Pt Sn/ γ Al 2O 3(c) is very broad and homogeneous from 40 to 110 kJ/mol. It is the significant difference between Pt Sn/ γ Al 2O 3(c) and the other catalyst.

关 键 词：一氧化碳 吸附 氧化铝 贵金属 负载型催化剂 

分 类 号：O643.36[理学—物理化学]