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用程序升温还原(TPR)方法研究了不同组成V_2O_5-SnO_2样品的还原性能,并对不同还原阶段样品进行了X射线衍射(XRD)及电子顺磁共振(EPR)测定。结果提供了还原过程中物相及钒离子价态变化的信息,发现由于钒离子在SnO_2中的高度分散及组分间的相互作用,V~(5+)的还原温度比纯V_2O_5有明显降低,说明V_2O_5-SnO_2二元氧化物体系比V_2O_5更易获得电子,上述现象与V_2O_5-SnO_2样品作为甲苯选择氧化催化剂所表现的相当高的活性密切相关。
The reduction performance of V2O5-SnO 2 samples with different compositions was investigated by temperature-programmed reduction (TPR). X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) measurements were performed on the samples in different reduction stages. The results provided information on the valences of the phases and vanadium ions in the reduction process. It was found that the V 5+ reduction temperature was significantly lower than that of the pure V 2 O 5 because of the high dispersion of vanadium ions in SnO 2 and the interaction between the components , Indicating that V 2 O 5-SnO 2 binary oxide system is easier to get electrons than V 2 O 5. The above phenomenon is closely related to the relatively high activity of V 2 O 5 -SnO 2 as a toluene selective oxidation catalyst.