关键词: 金属氧化物催化剂, 还原, 氧化物, 稀土化合物, 合成气合成氨

A TG-DTA thermal analyzer was used to study the reduction characteristics and kinetics of spherical molten Fe catalysts promoted with Al2O3, K2O, CaO, and some rare earth oxides. If the other constituents are unchanged, the rate of reduction decreases as the ionic radii of the added rare earth ions decrease. For the same kinds of rare earth oxides, the rates of reduction decrease as the amts. of added trivalent rare earth oxides increase. The reduction kinetics of several highly active reduction catalysts containing rare earth oxides were studied. The core and shell model may be applied. If q is the degree of reduction at time t for an isothermal catalyst reduction, a plot of 1-(1-q)1/3 vs. t gives a broken line. The activation energies can be calculated for different stages of reduction Both the step temperature programed reduction and the intrinsic kinetics of isothermal reduction show that it is possible to develop improved catalysts containing rare earth oxides with better reducibility than the current industrial spherical catalyst A110-5Q.

Key words: METALLIC OXIDE CATALYST, REDUCTION, OXIDE, RARE EARTH COMPOUNDS, AMMONIA SYNTHESIS