过渡金属原位掺杂Pt/TiO_2的喷雾燃烧制备及其CO氧化性能

Transition Metal In situ Doping Pt/TiO_2 by Flame Spray Pyrolysis for CO Oxidation

CO催化氧化不仅是一种典型的多相催化反应模型,而且在气体净化方面也有许多实际用途。用喷雾燃烧一步法制备了TiO2负载Pt的催化反应体系,通过原位掺杂Fe、Mn元素来提高Pt/TiO2体系在CO催化氧化应用中的活性。系统考察了Fe、Mn掺杂后对产物的晶相、负载颗粒的大小和价态、载体表面氧种类以及体系表面还原性能的影响规律,研究了Fe、Mn等元素在催化反应过程的作用机理。结果表明,Fe、Mn掺杂于Pt/TiO2体系后,CO被完全氧化的温度降低了40℃,而且在通过Mn掺杂后,催化剂在30℃下的TOF值(单位时间内1mol催化剂上转化的反应底物的物质的量)提升了一个数量级,比增加相同质量比例的贵金属Pt表现出更高的催化活性,为低成本、高活性催化剂的设计和制备提供了新思路。

Due to the absence of side reactions during the reaction process,carbon monoxide(CO)oxidation,as a typical heterogeneous catalytic reaction model to study the surface redox properties of catalysts,has been extensively studied.It also has many practical uses in gas purification,especially in the purification of automotive exhaust and removal of CO from H2for proton exchange membrane fuel cell(PEMFC).Flame spray pyrolysis(FSP)based on the traditional gas-phase combustion of nano-materials,with the characteristics of no post-processing,low cost and easy to large continuous process,has been widely used in the field of catalyst preparation and application.The method of preparing the coexistence of different noble metals and transition metal oxides,taking advantage of the synergy between the elements to improve the activity of catalysts has become an optimized scheme for many researchers.In this paper,a Pt loading catalytic system was prepared by flame spray pyrolysis,and the activity of Pt/TiO2system in CO oxidation was largely enhanced by in situ doping Fe and Mn in the spray flame.The effects of Fe and Mn on the crystal phase,specific surface area(SSA),the size and valence of supported particles,the oxygen species on the surface of the support and the surface reduction performance of the system were investigated by X-ray diffraction(XRD),N2adsorption-desorption isotherms,transmission electron microscope(TEM),CO chemisorption,X-ray photoelectron spectroscopy(XPS)and hydrogen temperature programmed reduction(H2-TPR),respectively.The roles of Fe,Mn in the catalysts on the catalytic reaction were also systematically analyzed.The results showed that the addition of Fe and Mn to the Pt/TiO2system lowered the temperature at which CO was completely oxidized by40℃,especially when Mn was doped in the Pt/TiO2,the TOFs increased by an order of magnitude,making the activity of catalysts even higher than that of the sample when the same mass ratio of Pt was added.Thus an effective way to improve the catalytic activity and to reduce the cost is proposed.