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通过浸渍还原法制备了不同比例的Pt-Mo/SiO_2催化剂,采用X射线衍射、透射电镜、X射线近边吸收谱和X射线光电子能谱表征了Pt-Mo/SiO_2催化剂的组成、结构及价态.研究结果表明,少量MoO_x修饰Pt-Mo/SiO_2催化剂在低温水汽变换反应中表现出比Pt/SiO_2催化剂更高的催化活性,过量MoO_x包覆的Pt-Mo/SiO_2催化剂活性较低.低温水汽变换反应活性来自于Pt与表面MoO_x的界面协同作用,限域在Pt纳米颗粒表面的MoO_x表现出较低价态,高分散MoO_x纳米岛修饰的Pt纳米颗粒是低温水汽变换反应的活性结构.
Different proportions of Pt-Mo / SiO 2 catalysts were prepared by impregnation reduction method. The composition, structure and valence of Pt-Mo / SiO 2 catalysts were characterized by X-ray diffraction, transmission electron microscopy, X-ray absorption spectrum and X-ray photoelectron spectroscopy The results show that a small amount of MoO_x-modified Pt-Mo / SiO_2 catalyst exhibits higher catalytic activity than Pt / SiO_2 catalyst in low temperature water-vapor shift reaction, and the activity of Pt-Mo / SiO_2 catalyst coated with excess MoO_x is low. The water vapor shift reaction activity comes from the synergistic effect of interface between Pt and surface MoO_x. The limited range of MoO_x on the surface of Pt nanoparticles shows a lower valence state. The Pt nanoparticles modified with highly dispersed MoO_x nano-islands are the active structures of low temperature water vapor shift reaction.