CO加氢Rh-Mn-Li/SiO_2催化剂配比的优化及其CO脱附行为  

Optimization of Metal Ratio and CO Desorption Behavior of Rh-Mn-Li/SiO_2 Catalyst for CO Hydrogenation

作　　者：江大好[1,2] 丁云杰[1] 吕元[1] 朱何俊[1] 陈维苗[1] 王涛[1] 严丽[1] 罗洪原[1] 

机构地区：[1]中国科学院大连化学物理研究所,辽宁大连116023 [2]中国科学院研究生院,北京100049

出　　处：《催化学报》2009年第7期697-703,共7页

基　　金：国家重点基础研究发展计划(973计划;2005CB221403)

摘　　要：通过优化Rh-Mn-Li/SiO2催化剂配比,大大地提高了其催化CO加氢合成C2含氧化合物的性能,并利用吸附CO的程序升温脱附（CO-TPD）和程序升温表面反应（TPSR）等方法考察了助剂Mn和Li对Rh基催化剂表面CO脱附行为的影响.结果表明,在543~573K内,Rh担载量为1.5%时催化剂的Rh效率（ERh）最高.少量Mn的添加显著地提高了Rh基催化剂的ERh,C2含氧化合物的时空收率（STYC2-oxy）和选择性（SC2-oxy）.并且随着Mn含量增加,ERh和STYC2-oxy在Mn=0.53%时最高,但SC2-oxy一直缓慢增加.而随着Li含量增加,SC2-oxy显著增加,但是ERh和STYC2-oxy明显下降.CO-TPD和TPSR结果表明,助剂Mn和/或Li的添加改变了催化剂表面解离CO活性中心的数量及其解离CO的能力,从而影响催化剂的活性.另一方面,Mn和Li的添加提高了催化剂表面弱吸附CO的相对数量,从而使SC2-oxy提高.A highly efficient Rh-Mn-Li/SiO2 catalyst for CO hydrogenation to C2 oxygenates was developed by the optimization of metal ratio, and the effects of Mn and Li loadings on the CO desorption behavior of the catalyst were studied by temperature-programmed desorption of adsorbed CO （CO-TPD） and temperature-programmed surface reaction （TPSR） of adsorbed CO with H2. At 543-573 K, the Rh efficiency （ERh） reached the maximum when the Rh loading was 1.5%. The space time yield of C2 oxygenates （STYC2-oxy）, ERh, and the selectivity for C2 oxygenates （Sc2-oxy） were dramatically increased when a small amount of Mn was added to the Rh/SiO2 catalyst. STYc2-oxy and ERh reached the maximum when the Mn loading was 0.53%, while the Sc2-oxy increased slowly with increasing Mn loading. Sc2-oxy increased remarkably with increasing Li loading, while STYc2-oxy and ERh obviously decreased. The results of CO-TPD and TPSR showed that the addition of Mn to the Rh-based catalyst increased the number of active sites responsible for CO dissociation and their ability to dissociate CO and therefore increased the activity of the Rh-based catalyst. However, the number of active sites and their CO dissociation ability decreased with the addition of Li. On the other hand, the addition of Mn and Li increased the proportion of the active sites for nondissociative CO adsorption and therefore increased the SC2-oxy.

关 键 词：锰 锂 铑效率 助剂效应 二碳含氧化合物 一氧化碳 加氢 

分 类 号：O643.32[理学—物理化学]