论文部分内容阅读
对Ｎａ２ＭｏＯ４·２Ｈ２Ｏ，ＭｏＯ３，（ＮＨ４）６Ｍｏ７Ｏ２４·４Ｈ２Ｏ等结构典型的含相化合物及氧化态Ｋ—ＭｏＯ３／γ－Ａｌ２Ｏ３催化剂样品进行了ＥＸＡＦＳ测试，并以Ｎａ２ＭｏＯ４·２Ｈ２Ｏ为标样进行多层拟合计算，以研究各样品相组分的配位结构。ＭｏＯ３和钼酸铵的配位状态复杂，无序度较高，富里埃变换谱上对应Ｍｏ—Ｏ配位的峰相互迭加后峰形宽化、不对称，单层拟合误差较大，多层拟合所得Ｍｏ－Ｏ配位结构参数与实际值较好地符合；氧化态催化剂样品中，不含钾样品的Ｍｏ－Ｏ键长较短，钼组分主要以高分散的ＭｏＯ３微粒形式存在，含钾样品的Ｍｏ—Ｏ键长较长，钼组分主要以多钼酸盐的形式存在。
EXAFS tests were carried out on typical samples with phase structure such as Na2MoO4 · 2H2O, MoO3, (NH4) 6Mo7O24 · 4H2O and K-MoO3 / γ-Al2O3 catalysts in oxidation state and multi-layer fitting with Na2MoO4 · 2H2O as standard sample Calculated to study the phase structure of each sample component. The coordination states of MoO3 and ammonium molybdate are complex and the degree of disorder is high. The peaks corresponding to the Mo-O coordination peaks on the Fourier transform spectrum are widened and asymmetrical after being superimposed on each other, and the fitting error of the single layer is larger, The parameters of the Mo-O coordination structure obtained by the multi-layer fitting are in good agreement with the actual values. In the oxidized catalyst sample, the Mo-O bond length of the potassium-free sample is short and the molybdenum component is mainly in the form of highly dispersed MoO3 particles , The Mo-O bond length of potassium-containing samples is longer, and the molybdenum component is mainly in the form of polymolybdate.