A series of nickel-alumina catalysts with a Ni/Al ratio between 3 and 20 has been prepared by coprecipitation. The calcination and reduction of these samples have been studied by thermogravimetry and their structures after calcination and reduction at different temperatures has been examined by X-ray diffraction. The methanation activities of the final catalysts have been determined by differential scanning calorimetry. Whereas the alumina present in the samples with Ni/Al = 3 stabilises the catalysts against crystalline growth during both calcination and reduction, the effect is much less pronounced with higher nickel contents. The resultant catalysts for Ni/Al = 6, 9 and 20 were found to have activities comparable with those with Ni/Al = 3 as long as the calcination and reduction are carried out at relatively low temperatures. A model of the catalysts is proposed.
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机译：通过共沉淀制备了一系列Ni / Al比为3至20的镍-氧化铝催化剂。通过热重法研究了这些样品的煅烧和还原，并通过X射线衍射检查了它们在不同温度下的煅烧和还原后的结构。最终催化剂的甲烷化活性已经通过差示扫描量热法测定。 Ni / Al = 3的样品中存在的氧化铝可稳定催化剂，使其在煅烧和还原过程中均不会出现晶体生长，而镍含量较高时，效果却不那么明显。发现所得的Ni / Al ＝ 6、9和20的催化剂具有与Ni / Al ＝ 3的催化剂相当的活性，只要煅烧和还原在相对较低的温度下进行即可。提出了催化剂模型。
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