EFFECTS OF GAMMA-IRRADIATION AND LITHIUM-OXIDE DOPING ON SURFACE AND CATALYTIC PROPERTIES OF MANGANESE OXIDES SUPPORTED ON ALPHA-ALUMINA

The influence of gamma-irradiation and lithium oxide doping on surface and catalytic properties of manganese oxides loaded on alumina was investigated. The amount of lithium oxide was varied between 0.13 and 1.56 wt\% Li2O. The pure and different doped solids were heated in air at 400-1000-degrees-C. The surface properties namely specific surface area (S(BET)), total pore volume (V(p)) and mean pore radius (rBAR) were determined from nitrogen isotherm conducted at 77 K. The catalytic activity of various solids was investigated using the catalysis of CO oxidation reaction by O2 at different temperatures. The results obtained revealed that gamma-irradiation to doses ranged between 20 and 160 Mrad effected no measurable changes in the surface properties. However, this treatment brought about a noticeable decrease in its catalytic activity (44-60\%). The increase in lithium oxide content in the range 0.13-1.58 wt\% was accompanied by progressive decrease in S(BET) of the various solids.