利用X射线衍射、热重分析、X射线光电子能谱、透射电镜等方法,考察了反应温度对甲烷部分氧化Ni/SiC催化剂活性和积炭的影响.结果表明,在甲烷部分氧化过程中,反应温度不仅影响催化剂的活性,而且影响催化剂活性组分的存在形式、积炭量以及积炭的形貌.在500℃下,催化剂活性很低,表面Ni物种十分复杂,催化剂积炭严重,主要为碳纳米管.但在850℃下,催化剂具有稳定的高活性,活性组分表面物种主要为金属Ni,催化剂积炭量少,主要为壳状碳.
Influences of reaction temperature on catalytic and coking behaviors of 10% Ni/SiC catalyst for partial oxidation of methane were investigated by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy and transmission electron microscopy techniques. The results suggested that the reaction temperature influenced not only the catalyst activity, but also the surface species of the catalyst, coke content and morphology. The catalyst showed low activity at 500℃, and the surface Ni species existed as several different forms. The catalyst deactivation at the low temperature was mainly caused by coking, and the coke appeared in carbon nanotubes. At high temperature (850℃ ), the catalyst exhibited stable and high activity and the surface Ni species was mainly metal Ni. The deposited carbon was very little and had a layered morphology.