Chary Komandur V R, Sagar Guggilla Vidya, Srikanth Chakravarthula S, Rao Vattikonda Venkat
Catalysis Division, Indian Institute of Chemical Technology, Hyderabad--500,007, India.
J Phys Chem B. 2007 Jan 25;111(3):543-50. doi: 10.1021/jp063335x.
A series of zirconia supported copper oxide catalysts with varying copper loadings (1.2-19.1 wt %) were prepared by impregnation method. The catalysts were characterized by X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and temperature-programmed desorption of CO2. Copper dispersion and metal area were determined by N2O decomposition method. X-ray diffraction patterns indicate the presence of crystalline CuO phase beyond 2.7 wt % of Cu on zirconia. UV-visible diffuse reflectance spectra suggest the presence of two types of copper species on the ZrO2 support. XPS peaks intensity ratio of Cu 2p3/2 and Zr 3d5/2 was compared with Cu dispersion calculated from N2O decomposition. TPR patterns reveal the presence of highly dispersed copper oxide at lower temperatures and bulk CuO at higher temperatures. The basicity of the catalysts was found to increase with Cu loading, and the activity of the catalysts was also found to increase with the increase in Cu loading up to 2.7 wt % Cu loading. The catalytic properties were evaluated for the dehydrogenation of cyclohexanol to cyclohexanone and were related to surface properties of the copper species supported on zirconia.
采用浸渍法制备了一系列具有不同铜负载量（1.2 - 19.1 wt%）的氧化锆负载氧化铜催化剂。通过X射线衍射、紫外可见漫反射光谱、X射线光电子能谱（XPS）、程序升温还原（TPR）和二氧化碳程序升温脱附对催化剂进行了表征。采用N₂O分解法测定了铜的分散度和金属面积。X射线衍射图谱表明，氧化锆上铜含量超过2.7 wt%时存在结晶CuO相。紫外可见漫反射光谱表明，ZrO₂载体上存在两种类型的铜物种。将Cu 2p3/2和Zr 3d5/2的XPS峰强度比与由N₂O分解计算得到的铜分散度进行了比较。TPR图谱显示，较低温度下存在高度分散的氧化铜，较高温度下存在体相CuO。发现催化剂的碱性随铜负载量的增加而增加，并且催化剂的活性也随铜负载量增加至2.7 wt%而增加。对环己醇脱氢制环己酮的催化性能进行了评价，并将其与负载于氧化锆上的铜物种的表面性质相关联。
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