Acta Phys. -Chim. Sin. ›› 1995, Vol. 11 ›› Issue (05): 401-406.doi: 10.3866/PKU.WHXB19950504

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Co or/and NO Adsorption on Reduced Rh2/SiO2 and Rh2-V/SiO2 Catalysts Characterized by Infrared Spectroscopy

Li Jun, Li Xin-Sheng, Zhou Jian-Lue, Xin Qin, Zhang Hui, Chen Yao-Qiang, Chen Yu   

  1. Analytical testing Center,Sichuan University,Chengdu 610064|State Key Laboratory of Catalysis,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116023|Department of Chemistry,Sihuan University,Chengdu 610064
  • Received:1994-05-21 Revised:1994-10-11 Published:1995-05-15
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Abstract:

CO and/or NO adsorption on reduced Rh2/SiO2 and Rh2-V/SiO2 catalysts has been studied by in situ infrared spectroscopy. The catalysts were prepared from Rh2 (CO)4Cl2 as a precursor. Three kinds of Rh sites are identified by CO adsorption corresponding to absorbance bands at 2085, and 2028cm-1 (RhⅠ(CO)2), 2060cm-1 (RhⅡCO),1867cm-1 (Rh2ⅢCO), respectively. IR bands of NO adsorption on Rh sites appears at 1748and 1648cm-1, which can be assigned to Rh-NO and Rh-Noδ- species, respectively. Addition of vanadium oxide to Rh2/SiO2 catalyst, decreases remarkly the number of RhⅡ and RhⅢ sites, and enhances the bond energy of RhⅠ(CO)2. The vanadium promotion is suggested as due to the electron transfer from Rh°to vanadium ions on Rh2-V/SiO2 catalyst. The results obtained from CO and NO adsorption on supported Rh and Rh-V catalysts derived from cluster and metal salt precursors, i.e., Rh2 (CO)4Cl2 and RhCl3, have been compared. It is found that the intensity of linear adsorbed CO on Rh2/SiO2 catalyst is more intense than that on Rh/SiO2 catalyst, this indicates that more Rh°sites were produced on Rh2/SiO2 catalyst. Rh2-V/SiO2 catalyst exhibits stronger electronic interaction between Rh metal and vanadium ions than that on Rh2-V/SiO2 catalyst.

Key words: CO or/and NO adsorption, IR spectroscopy, Rh2-V/SiO2 catalyst