经PPh_3修饰的Rh/SiO_2催化剂的吸附-脱附性能  

Adsorption-Desorption Behavior of Rh/SiO_2 Catalyst Modified with PPh_3 Ligand

作　　者：朱何俊[1] 丁云杰[1] 严丽[1] 李显明[1] 熊建民[1] 潘振栋[1] 江大好[1] 林励吾[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

出　　处：《催化学报》2005年第10期884-888,共5页

基　　金：国家自然科学基金资助项目(20073046);国家重点基础研究发展计划项目(2003CB615803)

摘　　要：应用程序升温技术研究了氢甲酰化反应物CO,H2和C2H4在经PPh3修饰的Rh/SiO2(PPh3-Rh/SiO2)催化剂上的吸附-脱附行为.CO-TPD结果显示,Rh/SiO2催化剂在348,398和525 K处有3个脱附峰,PPh3-Rh/SiO2催化剂仅在368 K处出现脱附峰,表明催化剂的吸附性能发生了明显变化.采用原位红外光谱研究了PPh3-Rh/SiO2催化剂上CO的吸附态.结果表明,2 040 cm-1处吸收峰归属于PPh3修饰的Rh粒子上线式吸附的CO.这种吸附态既不同于Rh/SiO2多相催化剂表面Rh粒子上的CO吸附态,也不同于相应均相催化剂中的羰基配位态.TPD和FT-IR结果表明,在低压下PPh3-Rh/SiO2催化剂对氢甲酰化反应已具有相当的催化性能.The temperature-programmed desorption （TPD） was employed to investigate the adsorption-desorption behavior of CO, H2 and C2H4 on the Rh/SiO2 catalyst modified with PPh3 ligand （PPh3-Rh/SiO2）. The result showed that there were three CO desorption peaks at 348, 398 and 525 K on Rh/SiO2, while only one CO desorption peak at 368 K was observed on PPh3-Rh/SiO2. Analogously, only one desorption peak of H2 and C2H4 appeared on PPh3-Rh/SiO2. These results implied that the adsorption-desorption behavior of CO, H2 and C2H4 on PPh3-Rh/SiO2 was different from that on Rh/SiO2. The adsorption states of CO on PPh3-Rh/SiO2 were studied using in situ FT-IR technique. The result revealed that the IR absorption peak at 2 040 cm^-1, corresponding to the CO-TPD desorption peak at 368 K on PPh3-Rh/SiO2, was assigned to the linear CO state on the surface PPh3-modified Rh particles. This adsorption-desorption behavior of CO on PPh3-Rh/SiO2 was not only different from that of Rh/SiO2, but also distinguished from that of carbonyl on homogeneous catalysts. The TPD and FT-IR results indicated that the PPh3-Rh/SiO2 had catalytic performance for hydroformylation at lower pressure.

关 键 词：氢甲酰化 三苯基膦 铑 氧化硅 负载型催化剂 吸附-脱附 

分 类 号：O643.361[理学—物理化学]