| 摘要 |
Nickel-alumina catalysts having a remarkably high degree of thermal stability, and active for the hydrogenation of carbon oxides (methanation), are prepared by a novel "precipitative-occlusion" method. This method involves digesting a slurry of an alumina hydrate in an aqueous solution of an amino complex of a nickel salt. The digestion is carried out at a temperature sufficiently high to decompose the amino complex and "release" the nickel (II) ions. This results in a gradual precipitation of nickel hydroxide in the pores and interstices formed by the agglomerating particles of alumina hydrate. The coflocculated solids are recovered as by filtration, washed, dried and calcined. The resulting compositions are found, in high temperature reactions such as methanation, to retain their activity for much longer periods of time than do conventional nickel-alumina catalysts prepared by the most widely used prior art technique, viz., coprecipitation.
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