镧系元素对Pd/Al2O3的修饰及其与丙烯腈气相加氢的关联

用浸渍法制备了镧系元素(Ce,La,Sm)修饰的低负载Pd(0.05 w.t%)/A l2O3催化剂,并应用于丙烯腈选择性加氢反应,实验结果表明:这种方法制备的催化剂对丙烯腈具有很好的选择性,镧系元素的添加大大促进了催化剂的活性和稳定性。XRD的测试结果表明稀土元素铈的添加减弱了Pd和载体A l2O3之间的相互作用,从而导致了Pd从载体表面游离出来。从TEM照片上可以看出催化剂颗粒尺寸的变化。XPS的测试结果表明用镧系元素修饰的Pd的结合能向较高能级发生了转移,从而使得钯被还原为零价。

Modification of lanthanide elements to Pd/Al2O3 and its corrlation to gas hydrogenation of acrylonitrile

Low-loaded Pd(0.05w.t%)/Al2O3 catalysts promoted with lanthanide elements(Ce,La,Sm) were prepared by wet impregnation method.Experiment of seletive hydrogenaqtion of acrylonitrile indicated that the as-prepared catalysts showed a good selectivity to propionitrile and the addition of lanthanide elements greatly improved the activity and stability.XRD results showed cerium interacted with the support γ-Al2O3 to weaken the interaction between Pd and Al2O3, resulting in free Pd from the support.From the TEM images we can see the change of the particle size of the catalysts.From the XPS results,the binding energies of Pd promoted with lanthanide were shifted to higher energies and palladium species had been reduced to zero valence.