Raman Spectroscopic Study of V/θ-Al2O3 Catalysts: Quantification of Surface Vanadia Species and Their Structure Reduced by Hydrogen
Raman Spectroscopic Study of V/θ-Al2O3 Catalysts: Quantification of Surface Vanadia Species and Their Structure Reduced by Hydrogen
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DOI：
10.1021/jp074223o
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发表时间：
2007-10
影响因子：
3.7
通讯作者：
Zili Wu;P. Stair;S. Rugmini;S. Jackson
中科院分区：
文献类型：
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作者：
Zili Wu;P. Stair;S. Rugmini;S. Jackson
利用原位紫外可见拉曼光谱和紫外漫反射光谱研究了负载型钒催化剂的两个有趣的问题：不同表面钒物种的定量和这些钒物种的氢还原。以漫反射系数作为外标，可以对V/θ-Al_2O_3的拉曼强度测量结果进行自吸收效应的修正。基于在拉曼光谱中选择性地检测一钒酸盐(UV激发)、多钒酸盐(可见光激发)和V2O5(可见光激发)的能力，成功地定量了脱水V/θ-Al_2O_3样品上存在的单钒酸盐、多钒酸盐和V2O5的分布与表面VOx密度的函数关系。结果表明，在所研究的所有表面VOx密度下都存在单钒酸盐物种，但在低表面VOx密度下是优势物种。在中、高表面VOx密度下，表面也存在多钒酸盐和V2O5，并以V2O5为主。紫外线--还有..。
Two interesting topics about supported vanadia catalysts were studied using in situ UV and visible Raman and UV−vis diffuse reflectance spectroscopy (DRS): The quantification of different surface vanadia species and the hydrogen reduction of these vanadia species. Using the diffuse reflectance value as an external standard, we could correct the Raman intensity measurements of V/θ-Al2O3 for the self-absorption effect. On the basis of the ability to selectively detect monovanadate (UV-excited), polyvanadate (visible-excited), and V2O5 (visible-excited) in the Raman measurements, the distribution of monovanadate, polyvanadate, and V2O5 present on dehydrated V/θ-Al2O3 samples was successfully quantified as a function of surface VOx density. It is shown that monovanadate species are present at all surface VOx densities studied but are the dominant species at low surface VOx density. Polyvanadate and V2O5 are also present and predominate on the surface at intermediate and high surface VOx density. The UV- and ...