摘要
利用CO和NO作为双探针分子和TP-IR动态方法研究了Rh^+Co/A1_2O_3催化剂上的吸附中心类型,CO吸附态的动态行为以及CO歧化反应.结果表明在Rh+Co/Al_2O_3上存在大量的孪生CO吸附中心和少量的线式CO吸附中心以及Co上的NO吸附中心.在TPD(真空中)动态过程中,孪生CO谱带强度逐渐减弱并在325℃完全脱除.明显低于Rh_4/Al_2O_3上孪生CO谱带的脱附温度,表明Co的加入减弱了孪生中心对CO的吸附强度.在TP(CO中)动态过程中,吸附的CO谱带在250℃以上才发生强度减小直至消失的行为表明CO歧化在250℃以上才发生.并且孪生中心上的歧化速率高于线式中心.
Metal - metal and metal - support interaction on Rh + Co/Al2O3 prepared by co -impregnation and Rh2Co2/Al2O3 by using RhCo carbonyl cluster as the precusor have been studied in detail by X - ray Photoelectron Spectroscopy(XPS). It was found that binding energy for Rh3d on Rh + Co/Al2O3 reduced with H2 at 400℃ is nearly identical with that of Rh0, and Co exists essentially in CoAl2O4 state and only the very small amount of Co exists as Co0. On Rh2Co2/Al2O3 reduced with H2 at 400℃ Rh exists as Rh0, and a part of Co exists in CoAl2O4 state whereas another part of Co exists as Co0. Results above indicate that Rh - A12O3 interaction for Rh + Co/Al2O3 and Rh2Co2/Al2O3 is weak, and Co - Al2O3 interaction is strong; Rh - Co interaction on Rh + Co / Al2O3 prepared by coimpregnation of RhCl3 and Co ( NO3)2 is weak , but on Rh2Co2/Al2O3 prepared by using RhCo carbonyl cluster as the precusor the strong Rh -Co interaction of RhCo carbonyl cluster is still maintained resulting in the considerable amount of Co0
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1996年第7期661-666,共6页
Acta Chimica Sinica
基金
国家自然科学基金
催化基础研究国家重点实验室基金资助课题
