EFFECTS OF GAMMA-IRRADIATION AND LI2O-DOPING ON SURFACE AND CATALYTIC PROPERTIES OF UNLOADED CO3O4 SOLID

The effects of gamma-irradiation (20-160 Mrad) and lithium oxide doping (0.75-6 mol%) on the surface and catalytic properties of unloaded Co3O4 solid have been investigated, The surface characteristics of various solids were determined from nitrogen adsorption isotherms taken at -196 degrees C and their catalytic activities were measured by following the kinetics of CO-oxidation by O-2 at 110-150 degrees C using a static method, The results showed that gamma-rays brought about a decrease of 21% in S-BET of Co3O4 due to widening of its pores and led also to a considerable increase in its catalytic activity. A maximum increase of 91% was observed upon exposure to a dose of 80 Mrad, Lithium oxide-doping at at 500 degrees C resulted in an increase of 150% in S-BET Of treated solid without changing its mean pore radius, This treatment was also accompanied by an increase of about 50% in its catalytic activity measured at 150 degrees C, Gamma-irradiation and Li2O-doping of unloaded Co3O4 did not change the magnitude of apparent activation energy of catalysis of CO-oxidation by O-2 but increased the concentration of catalytically active sites contributing in the catalytic process, In other words, gamma-rays and lithium oxide doping did not alter the mechanism of catalytic oxidation of CO by O-2 over unloaded cobaltic oxide solid.