Abstract: To reveal the chemical species of copper, typically the low-valence speices, in Cu-Zn-Al catalyst prepared by complete liquid-phase method before reduction, the effects of heat-treatment atmosphere, interactions among all components and copper precursor on heattreatment have been systematically studied during the heat treatment of several different kind of copper precursor in liquid paraffin. The results showed that Cu2+ could be reduced by liquid paraffin under heating condition. The Cu+ is formed before the formation of Cu. The reductive degree of Cu2+ was related with the category of copper salts and heat-treatment temperature. CuO can be reduced to Cu2O by liquid paraffin at 240 ℃, and then to Cu at 300 ℃. The copper nitrate could be easily reduced by liquid paraffin than copper acetate at the same temperature. The reason of the low-valent copper appearing in Cu-base catalyst prepared by complete liquid-phase method before reduction could be attributed to the presence of liquid paraffin.

Key words: copper, cuprous oxide, liquid paraffin