A Cu metal surface was evaluated by a novel technique combining temperature
-programmed reduction (TPR) measurement with N2O oxidation. The technique c
onsists of three steps: the usual TPR measurement, the oxidation of the Cu
surface by N2O, and the subsequent TPR measurement. The surface Cu oxidized
by N2O was determined as a ratio of the peak area of the second TPR profil
e to that of the first one. It was found that bulk oxidation gradually proc
eeds after surface oxidation even at 30 degreesC. After the surface oxidati
on, the Cu2O produced by N2O oxidation varied with N2O exposure time (t) an
d had a linear correlation with ta at temperatures below 100 degreesC. The
linear correlation in the parabolic plot proves that bulk oxidation proceed
s through the diffusion process, and the Y-intercept corresponds to the sur
face oxidation. Both the dispersion and the Cu metal surface area of the sa
mple were calculated from the intercept in the parabolic plot for the Cu2O
produced by N2O oxidation. In addition, we found that a very large Cu metal
surface area, as high as 32 m(2) g(cat)(-1), was created on a Cu-MgO catal
yst through a citrate process using a molten mixture of copper nitrate, mag
nesium nitrate, and citric acid. (C) 2000 Academic Press.