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制备了一系列甲烷选择氧化制甲醛的Mo/ZrO2 催化剂 .采用催化剂性能评价、BET比表面积测定、XRD、共焦显微激光拉曼光谱、H2 TPR和XPS等方法研究比较了不同Mo担载量催化剂的性能及其结构和性质 .实验结果表明 :Mo/ZrO2 催化剂具有催化选择氧化甲烷制甲醛的性能 ,且对甲醛有较高的选择性 .在所考察的范围内 ,随着催化剂Mo担载量的增加 ,甲烷的转化率增加 ,甲醛的选择性增加 ,甲醛的比活性增加 .随着反应温度的升高 ,甲烷的转化率增加 ,甲醛的选择性降低 ,甲醛比活性升高 .Mo/ZrO2 催化剂中主要含有ZrO2 和Zr(MoO4 ) 2 .催化剂的性能和性质与催化剂中Zr(MoO4 ) 2 的性质密切相关 .随着Mo担载量的增加 ,Zr(MoO4 ) 2 晶粒尺寸增大 ,并且其含量增加 ;ZrO2 晶粒尺寸基本不变 .Zr(MoO4 ) 2 晶粒尺寸增大和含量增加导致催化剂的比表面积降低 ,使甲烷选择氧化生成甲醛的钼氧物种增多 ,催化剂的还原温度升高和表面Mo的配位不饱和程度降低 .从而使得Mo含量较高的催化剂 (12 %Mo/ZrO2 )具有较高的甲烷选择氧化生成甲醛的活性
A series of Mo / ZrO2 catalysts for the selective oxidation of methane to formaldehyde were prepared.The catalysts were characterized by means of catalyst performance evaluation, BET specific surface area measurement, XRD, confocal laser Raman spectroscopy, H2 TPR and XPS. Performance and its structure and properties.The experimental results show that: Mo / ZrO2 catalyst has the catalytic performance of selective oxidation of methane to formaldehyde, and has a higher selectivity to formaldehyde in the investigated range, with the catalyst Mo loading As the reaction temperature increases, the conversion of methane increases, the selectivity of formaldehyde decreases, and the specific activity of formaldehyde increases.Mo / ZrO2 catalyst Mainly contains ZrO2 and Zr (MoO4) 2. The properties and properties of the catalyst are closely related to the properties of Zr (MoO4) 2 in the catalyst, and the grain size of Zr (MoO4) 2 increases with the increase of Mo loading The content of ZrO 2 increases with the increase of ZrO 2 content and the grain size of ZrO 2 is almost unchanged.The increase of grain size and content of ZrO 2 decreases the specific surface area of the catalyst, , The reduction temperature of the catalyst increases and the degree of coordination unsaturation of the surface Mo decreases, so that the catalyst with higher Mo content (12% Mo / ZrO2) has higher methane selective oxidation activity to form formaldehyde