双金属RhAux/γ - Al203催化剂的CO催化氧化反应活性

采用超声辅助膜扩散法制备了双金属RhAu/γ- Al2O3催化剂(x=0、0.25、0.5、1.0、2.0和4.0),研究了该系列催化剂的CO催化氧化反应活性.采用程序升温还原(TPR)、X射线衍射(XRD)、原位DRIFTS和电子透射显微镜(TEM)等技术对催化剂的结构、形貌和物化性能进行了表征.结果表明,双金属Rh...

Activity of bimetal RhAux/γ-Al2O3 catalysts for CO catalytic oxidation

Abstract： RhAux/γ-Al2O3 （ x = 0,0.25,0.5,1.0,2.0,4. 0） catalysts were prepared by the ultrasound- assisted membrane reduction method. The activity of the catalysts for CO catalytic oxidation was investigated. RhAux/γ-Al2O3 catalysts were characterized by TPR, XRD, in-situ DRIFTS and TEM techniques. The results showed that RhAux/γ-Al2O3catalysts possessed higher activity for CO oxidation than Rh/γ-Al2O3 catalyst. The activity of CO catalytic oxidation decreased as the following order of RhAu4/γ-Al2O3 RhAu2/γ-Al2O3≈ RhAu/γ-Al2O3 ≈ RhAu0.5/γ-Al2O3 〉 RhAu0.25/γ-Al2O3 〉 Rh/γ-Al2O3〉 Au/γ-Al2O3. Au in RhAux/γ-Al2O3 catalysts had significantly adjusting effects on the distribution of RhAux metal nanopartiele size, redox properties, CO adsorption and the catalytic activity for CO oxidation. The experimental results showed that there was an interaction between Rh and Au atoms. After H2 reduction, the segregation phenomenon of Au in RhAux nanoparticles on the surface of the catalysts occurred. A certain structure of core-shell was formed and Rh active sites were covered by Au atoms, arousing the decrease of in catalytic activity for CO oxidation as the RhAux/r - A1203 catalysts were reduced by H2.