Kühn Sven, Schmidt-Zhang Peter, Hahn Alexander Hp, Huber Manoup, Lerch Martin, Ressler Thorsten
Technische Universität Berlin, Institut für Chemie, Sekr, C2, Strasse des 17, Juni 135, D-10623 Berlin, Germany.
Chem Cent J. 2011 Jul 15;5(1):42. doi: 10.1186/1752-153X-5-42.
Molybdenum oxide nitride (denoted as Mo(O,N)3) was obtained by ammonolysis of α-MoO3 with gaseous ammonia. Electronic and geometric structure, reducibility, and conductivity of Mo(O,N)3 were investigated by XRD, XAS, UV-Vis spectroscopy, and impedance measurements. Catalytic performance in selective propene oxidation was determined by online mass spectrometry und gas chromatography. Upon incorporation of nitrogen, Mo(O,N)3 maintained the characteristic layer structure of α-MoO3. XRD analysis showed an increased structural disorder in the layers while nitrogen is removed from the lattice of Mo(O,N)3 at temperatures above ~600 K. Compared to regular α-MoO3, Mo(O,N)3 exhibited a higher electronic and ionic conductivity and an onset of reduction in propene at lower temperatures. Surprisingly, α-MoO3 and Mo(O,N)3 exhibited no detectable differences in onset temperatures of propene oxidation and catalytic selectivity or activity. Apparently, the increased reducibility, oxygen mobility, and conductivity of Mo(O,N)3 compared to α-MoO3 had no effect on the catalytic behavior of the two catalysts. The results presented confirm the suitability of molybdenum oxide nitrides as model systems for studying bulk contributions to selective oxidation.
通过用气态氨对α-MoO₃进行氨解反应制得了氮氧化钼（表示为Mo(O,N)₃）。采用X射线衍射（XRD）、X射线吸收光谱（XAS）、紫外可见光谱以及阻抗测量等方法对Mo(O,N)₃的电子和几何结构、还原性及导电性进行了研究。通过在线质谱和气相色谱测定了其在丙烯选择性氧化反应中的催化性能。引入氮后，Mo(O,N)₃保持了α-MoO₃的特征层状结构。XRD分析表明，在高于约600 K的温度下，当氮从Mo(O,N)₃的晶格中脱除时，层内结构无序度增加。与常规的α-MoO₃相比，Mo(O,N)₃表现出更高的电子和离子导电性，且丙烯在更低温度下开始还原。令人惊讶的是，α-MoO₃和Mo(O,N)₃在丙烯氧化起始温度、催化选择性或活性方面没有可检测到的差异。显然，与α-MoO₃相比，Mo(O,N)₃增加的还原性、氧迁移率和导电性对这两种催化剂的催化行为没有影响。所呈现的结果证实了氮氧化钼作为研究体相贡献对选择性氧化影响的模型体系的适用性。
