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通过胶溶法制备碳纳米管(CNTs)-γ-Al2O3复合材料,并以其为载体,采用共浸渍法制备一系列Pt-Ni双金属催化剂用于富氢气体中CO优先氧化。采用N2物理吸附脱附、X射线衍射(XRD)、H2-程序升温还原(H2-TPR)、透射电子显微镜(TEM)、扫描透射电子显微镜(STEM)和扫描电子显微镜(SEM)技术对催化剂进行了表征。在低温条件下,Pt-Ni/CNTs-γ-Al2O3催化剂在CO优先氧化反应中表现出高的活性和选择性,并具有宽的净化CO温度窗口。复合材料中的CNTs被氧化铝包裹,低温条件下还原所得Pt-Ni合金纳米颗粒均匀分布在Al2O3表面。该催化剂优良的催化性能归因于Pt-Ni合金的形成和CNTs的添加避免或减缓了热点的形成。热点的存在导致氧气用于H2氧化的选择性提高,并且会促使逆水汽变换反应的发生,两者均对CO的消除有害。
A series of Pt-Ni bimetallic catalysts were prepared by co-impregnation method for the preferential oxidation of CO in hydrogen-rich gas through the gravimetric method to prepare carbon nanotubes (CNTs) -γ-Al2O3 composite. The catalysts were characterized by N2 physisorption desorption, X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR), transmission electron microscopy (TEM), scanning transmission electron microscopy (SEM) and scanning electron microscopy (SEM) Characterization. At low temperature, the Pt-Ni / CNTs-γ-Al2O3 catalyst shows high activity and selectivity in the CO preferential oxidation reaction and has a wide purification CO temperature window. The CNTs in the composite material is surrounded by alumina, and the Pt-Ni alloy nanoparticles obtained by the reduction at low temperature are evenly distributed on the surface of the Al2O3. The excellent catalytic performance of the catalyst is attributed to the formation of Pt-Ni alloy and the addition of CNTs to avoid or slow the formation of hot spots. The presence of hot spots leads to a selective increase of oxygen for H2 oxidation and can lead to the occurrence of counter-water vapor shift reactions, both of which are detrimental to the elimination of CO.