氧化铝负载高分散γ-Mo_2N的制备与结构表征  

Preparation and Structural Characterization of Highly Dispersed γ-Mo_2N Supported on Alumina

作　　者：孟明[1] 伏义路[1] 刘振林[1] 姜明[1] 谢亚宁[2] 胡天斗[2] 

机构地区：[1]中国科学技术大学化学物理系,合肥230026 [2]中国科学院高能物理研究所,北京100039

出　　处：《高等学校化学学报》2002年第6期1113-1116,共4页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金 (批准号 :2 9873 0 44 )资助

摘　　要：由 NH3的程序升温还原反应 (TPR)制备了不同 Mo担载量的氮化态 Mo/γ-Al2 O3催化剂 ,用 XRD和EXAFS方法研究了样品在氮化前后的体相结构及 Mo原子局域配位结构 .氮化前样品的 Mo K-边径向结构函数与非负载 Mo O3类似 ,样品中 Mo以晶粒度较小 ,分散度较高的 Mo O3形式存在 ;氮化后样品的径向结构函数与非负载的 γ-Mo2 N基本相同 ,样品中 Mo主要以分散度较高的 γ-Mo2 N形式存在 .EXAFS拟合结果表明 ,样品的第一配位壳层 (Mo— N)的配位数较非负载 γ-Mo2 N有明显降低 ,热无序和结构无序均较大 ,并且随担载量降低 。The nitrided Mo/Al 2O 3 catalysts were prepared by temperature programmed reaction between NH 3 and MoO 3/Al 2O 3. XRD and EXAFS methods were used for the structural characterization. The results of XRD show that the molybdenum species in the supported samples exist as a dispersed MoO 3 phase before nitriding. After nitriding, most of the molybdenum species were nitrided to form γ Mo 2N. The lower intensity of the radial structure functions of Mo K edge and the smaller coordination number of Mo-N shells accordingly indicate that the γ Mo 2N in the supported samples possesses a high dispersion, the lower the loading of Mo, the higher the dispersion of γ Mo 2N on alumina. From the view of coordination distance, it is found that with the increase of dispersion of γ Mo 2N, the Mo-N distance is a little shortened, which may be resulted from the nano shortening phenomenum. The values of disorder factors show that the γ Mo 2N phase in the supported samples has big thermal and structural disorder extent, and with the increase of its dispersion, both the thermal and structural disorder factors increase.

关 键 词：氧化铝负载 高分散 γ-Mo2N 催化剂 结构表征 EXAFS 氮化钼 催化活性 

分 类 号：O643.36[理学—物理化学] TQ426.6[理学—化学]