【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.更多还原

【Abstract】 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.更多还原