Cu/ZSM-5催化剂的表征及其环己醇脱氢性能

Characterization of Cu/ZSM-5 and Its Catalytic Property in Cyclohexanol Dehydrogenation

以制备的ZSM-5分子筛为载体,采用浸渍法制备了一系列Cu负载量不同的Cu/ZSM-5催化剂。采用X射线衍射、氢气程序升温还原、吸附氨气程序升温脱附和BET等方法对Cu/ZSM-5催化剂进行了表征,用H2-N2O滴定法测定了Cu金属的比表面积和分散度。以环己醇气相脱氢制备环己酮为探针反应对Cu/ZSM-5催化剂的催化性能进行了评价。实验结果表明,Cu负载量影响Cu物种在载体表面的状态和分布,Cu是环己醇脱氢反应的活性中心,其比表面积、分散度与Cu/ZSM-5催化剂的活性相关,Cu/ZSM-5催化剂的B酸中心与环己醇脱氢反应的选择性相关。Cu质量分数5%的Cu/ZSM-5催化剂上Cu金属的比表面积较大而B酸中心较少,显示出很高的环己醇转化率(58.7%)和较好的环己酮选择性(97.2%)。

A series of Cu/ZSM -5 catalysts were prepared by impregnation method. The catalysts were characterized by means of XRD, HE - TPR, NH3 - TPD and BET. Both dispersity and specific surface area of copper were determined by HE - N2O titration. Performances of Cu/ZSM - 5 catalysts in probe reaction-gas phase dehydrogenation of cyclohexanol to cyclohexanone were investigated. Experiments showed that loading amount of Cu gave effect to distribution and status of Cu species on surface of support. Cu is active sites of cyctohexanol dehydrogenation. Specific surface area and dispersity of copper related with activity of the catalyst. Selectivity of the catalyst was affected by its acidity. When Cu mass fraction in Cu/ZSM -5 catalyst is 5%, the specific surface area of copper is large, its dispersion is high and acidity of the catalyst is weak. The catalyst shows the highest cyclohexanol conversion of 58.7%. Its selectivity to cyclohexanone reaches 97.2%.