采用等体积浸渍法制备了Pd/Al2O3和Rh-Pd/Al2O3密偶催化剂,运用H2程序升温还原、CO化学吸附和X射线光电子能谱等手段对催化剂进行了表征,并考察了催化剂对丙烷总包反应和单反应的转化活性.总包反应结果表明,Rh的添加使起燃温度和完全转化温度分别降低了23和18 oC.单反应结果证明,添加Rh能提高各单反应丙烷的转化活性,尤其是有NO参与的反应.表征结果证明,掺杂Rh不仅可以抑制活性组分PdOx的烧结,提高PdOx的分散度,而且可以改变其电子状态。
The close-coupled catalysts Pd/Al_2O_3 and Rh-Pd/Al_2O_3 were prepared by the impregnation method and characterized by H_2 temperature-programmed reduction,CO chemisorption,and X-ray photoelectron spectroscopy.Both overall catalytic activity and specific reactions associated with C_3H_8elimination were assessed.The light-off temperature and complete conversion temperature decreased by 23 and 18 °C,respectively,upon addition of Rh to the Pd/Al_2O_3 catalyst.The addition of Rh promotes the catalytic activity during C_3H_8 reactions,particularly in the presence of NO.The introduction of Rh not only inhibits sintering of PdO_x and increases the dispersion of these same species,but also changes the electronic state of the PdO_x in the catalyst.