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在一定实验条件下(焙烧温度<773K),NiO与γ-Al_2O_3之间发生强相互作用而使得Ni(Ⅱ)难以被H_2所还原.其实质是Ni(Ⅱ)进入了γ-Al_2O_3表面层上的四、六配位空位.按作者提出的掺入模型进行计算,实验也证实随着负载量增加表面空位均被Ni(Ⅱ)占据之后,过量NiO就以晶态附着在表面上.在有NiO晶相出现时,经873K以上高温处理,Ni(Ⅱ)、Al(Ⅲ)间的相互扩散导致在NiO微晶上形成类似非计量的NiAl_2O_4.扩散作用随预处理温度提高而加剧,最终形成结构较为完整的NiAl_2O_4尖晶石.与γ-Al_2O_3发生强相互作用的NiO也随之而增多.焙烧温度、负载量是影响相互作用的重要因素。
Under some experimental conditions (calcination temperature <773K), strong interaction between NiO and γ-Al_2O_3 makes Ni (Ⅱ) hard to be reduced by H_2, and the essence is that Ni (Ⅱ) enters the γ-Al_2O_3 surface layer Of the four, six coordination spaces .According to the authors proposed incorporation model calculation, the experiment also confirmed that as the loading increases the surface vacancies are occupied by Ni (Ⅱ), the excess NiO in the crystalline state attached to the surface in the presence of When the NiO crystal phase appears, the interfacial diffusion between Ni (Ⅱ) and Al (Ⅲ) leads to the formation of NiAl_2O_4 similar to the nonmetallic on the NiO crystallites by the high temperature treatment above 873 K. The diffusion increases with the pretreatment temperature and finally forms NiO 2 O 4 spinel with relatively complete structure.NiO with strong interaction with γ-Al 2 O 3 also increased.The calcination temperature and loading were the important factors affecting the interaction.