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本文用透射电子显微镜、选区电子衍射和X光衍射研究NiO/γ-Al_2O_3和CuO/γ-Al_2O_3体系,结果表明,氧化物在载体表面有单层分散和晶相两种状态。当氧化物含量低于某一阈值时,呈单层分散态,高于此阈值时出现晶相。氢还原研究表明,单层分散态比晶态难还原。晶相NiO在300—400℃还原,单层分散态则要450—530℃;晶相CuO在约180℃时还原,单层分散态则要240—400℃。无论是单层分散的或晶相的氧化物,还原得到的金属都是晶相,但单层分散的氧化物还原出来的金属晶粒较小。
In this paper, NiO / γ-Al_2O_3 and CuO / γ-Al_2O_3 systems were investigated by transmission electron microscopy, selected area electron diffraction and X-ray diffraction. The results show that the oxide has single-layer dispersion and crystalline phases on the surface of the support. When the oxide content below a certain threshold, the monolayer was dispersed, above which the crystalline phase appears. Hydrogen reduction studies have shown that monolayer dispersed state is more difficult to reduce than crystalline state. Crystal phase NiO reduction at 300-400 ℃, monolayer dispersed state to 450-530 ℃; crystalline phase CuO reduction at about 180 ℃, monolayer dispersed state to 240-400 ℃. Whether monolayer dispersed or crystalline phase oxides, the reduction of the metal is a crystalline phase, but the monolayer dispersed oxide smaller metal grains smaller.