- 作者: 王逸萍 ; 葉君棣
- 作者服務機構: 清華大學化學系
- 中文摘要:
The effects of reduction, evacuation and adsorbate adsorption on Mo/SiO/sub 2/ catalysts prepared by impregnation were studied by means of the electron paramagnetic resonance (EPR) technique. Pentavalent molybdenum species in the overlayer (Mo/sub 0/ /sup 5+/, g/sub .perp./=1.941, g/sub .dbar./=1.895) and at the interface(Mo/sub i//sup 5+/, g/sub .perp./=1.952, g/sub .dbar./=1.866) between MoO/sub 3/ and SiO/sub 2/ were distinguished in the EPR spectra. They were observed from samples reduced at T<573K and T>573K respectively. The difference in their natures reflected the extent of their interaction with the support. Mo/sub 0//sup 5+/ existed in the MoO/sub 3/ overlayer of the catalyst and interacted only weakly with the support. Mo/sub i// sup 5+/ from the Mo ions connected directly to SiO/sub 2/ was affected strongly by the support. The anisotropic factor of the measured Mo/sub i//sup 5+/ signals increased with the extent of support interaction.
Superoxide ions (O/sub 2//sup -/, g/sub 1/=2.016, g/sub 2/=2.011, g/sub 3/=2.006) were found upon oxygen adsorption on samples evacuated at temperatures above 573K. The observed O/sub 2/ may exist at the interface between MoO/sub 3/ and the support. - 英文摘要: --
- 中文關鍵字: Molybdenum Oxide; Impregnation; Electron Paramagnetic Resonance (Epr); Anisotropy
- 英文關鍵字: 氧化鉬;浸漬;電子順磁共振;各向異性