EFFECT OF LITHIUM-OXIDE DOPING ON SURFACE AND CATALYTIC PROPERTIES OF NIO/FE2O3 SOLIDS

The influence of Li2O doping (0.75-3.0 mol%) on surface and catalytic properties of NiO/Fe2O3, having a molar ratio of 1:2, was investigated. Pure and doped mixed solids were heated in air at 700 and 800 degrees C. The surface characteristics of various solids were determined from N-2-adsorption isotherms conducted at -196 degrees C and their catalytic activities were measured by following up the kinetics of CO oxidation by O-2 at 300-400 degrees C using a static method. The results revealed that the doping process brought about an increase in the specific surface area (S-BET) of mixed solids. A maximum increase of about two-fold was observed by treating with 1.5% Li2O. On the other hand, this treatment resulted in a drastic decrease (about 50%) in the catalytic activities of the doped catalysts. Lithium oxide doping altered the pre-exponential factor of the Arrhenius equation without changing the magnitude of the apparent activation energy of the catalytic reaction which might indicate that Li2O did not change the mechanism of the catalytic reaction.