激光喇曼光谱法测定MoO_3在载体表面的单层分散容量

Laser Raman Spectrometric Determination of the Monolayer Dispersion Capacities of MoO_3 on Supports

用激光喇曼光谱法测定了MoO_3/γ-Al_2O_3、MoO_3/TiO_2和MoO_3/SiO_2中聚集态MoO_3量和负载量的关系。外推得出的单层分散容量与从XRD、XPS及表面酸性测定中得出的结果相符,因而为MoO_3在载体表面单层分散的观点提供了直接的证据。从LRS谱中还得出一些XPS、XRD未能得出的结构信息。对LRS定量中遇到的一些问题、起因及解决办法也进行了讨论。

The relationship between aggregative MoO3 and total MoO3 loading in MoO3/γ-Al2O3, MoO3/TiO2 and MoO3/SiO2 was determined by LRS. KNO3 was used as the internal standard for the measurement of intensities. The obtained monolayer dispersion capacities by extrapolation correspond to those obtained by XPS, XRD and surface acidity measurement.Raman spectrometry can be used to indentify all molybdenum oxide species, for example the aggregative MoO3 fine particles, Al2(MoO4)3 and two dimensional Mo interaction species (monolayer dispersed MoO3). So this result is a direct and convincible evidence for the view of monolayer dispersion. Some informations about the structure of catalysts supporting MoO3 have been obtained by LRS, which was not obtained by XPS, XRD. The trouble in the quantitative LRS determination for catalysts, its cause and the method to overcome it are also discussed.