铜改性镍基催化剂制备及其催化联苯加氢性能

Preparation of Copper Modified Nickel-based Catalysts and Their Catalytic Hydrogenation Performance of Biphenyl

采用共浸渍法制备了一系列Cu改性的Ni基催化剂（x Ni-y Cu/Al2O3,x,y分别为Ni和Cu的含量,以Al2O3的质量为基准,下同）,用于联苯催化加氢制备环己基苯（CHB）。通过X射线粉末衍射（XRD）、BET、XPS及透射电子显微镜（TEM）对催化剂进行了表征。考察了催化剂50%Ni-10%Cu/Al2O3用量、H2压力、反应温度对联苯加氢制备环己基苯的影响。结果表明：Cu晶粒在催化剂表面优先析出,使表面Ni活性中心稀释、Ni晶粒尺寸变小,从而提高了CHB的选择性。当联苯为1.5 g,m（50%Ni-10%Cu/Al2O3）=0.5 g,以环己烷为溶剂、p（H2）=2.2 MPa、200℃反应4 h时,联苯的转化率可达94.7%,CHB的选择性达到99.8%。催化剂50%Ni-10%Cu/Al2O3循环使用9次后,联苯的转化率稍有降低,CHB的选择性几乎不变。

A series of copper modified nickel-based catalysts（x Ni-y Cu/Al2 O3, x, y is the content of Ni and Cu, respectively, on the base of the mass of Al2 O3, the same below） were prepared by impregnation method for the hydrogenation of biphenyl to cyclohexylbenzene（CHB）. The prepared catalysts were characterized by X-ray powder diffraction（XRD）, BET measurement, scanning electron microscope（SEM） and transmission electron microscope（TEM）. The effects of catalyst（50%Ni-10%Cu/Al2 O3） dosage, H2 pressure and reaction temperature on the hydrogenation of biphenyl to cyclohexylbenzene. The results showed that Cu particles on the surface of catalyst preferentially separated out, which could dilute Ni activity centers and lead to smaller Ni active particles, thus enhancing the selectivity of CHB. The conversion of biphenyl and the selectivity for CHB could reach 94.7% and 99.8%, respectively, under the conditions of 50%Ni-10%Cu/Al2 O3 0.5 g, cyclohexane as a solvent, H2 pressure 2.2 MPa, reaction temperature 200℃ and reaction time 4 h. In addition, the conversion of biphenyl decreased slightly, while the selectivity for CHB was almost unchanged after 50%Ni-10%Cu/Al2 O3 being recycled for nine times.