Surface and catalytic properties of a CuO/MgO system as influenced by Li2O-doping and exposure to γ-irradiation

The effects of Li2O-doping and γ-irradiation of a CuO/MgO system on its surface and catalytic properties have been investigated. The extent of CuO loading was varied between 9 and 37 wt.% and the dopant concentration was changed between 0.4 and 2.35 wt.% Li2O. The doses of γ-rays were ranged between 20 and 160 Mrad. Pure and variously doped solids were subjected to heat treatment at 400 °C. The results revealed that MgO dissolves CuO producing CuO–MgO solid solutions by heating the mixed solids at 400 °C. The maximum amount of CuO dissolved in MgO solid by heating at 400 °C attained 22.8 wt.%. The specific surface area of the system investigated decreased by increasing the amount of CuO present and by increasing the amount of dopant added. On the other hand, γ-irradiation brought about an increase in the SBET of the treated adsorbents. The catalytic activity in H2O2 decomposition of CuO/MgO system decreased by increasing the dose of γ-irradiation. The exposure of the CuO/MgO sample (containing 28.3 wt.% CuO) precalcined at 400 °C to a dose of 160 Mrad resulted in a decrease of 54.5% in its catalytic activity expressed as reaction rate constant, per unit surface area for the reaction conducted at 30 °C (k30 °C–). The Li2O-doping of the same catalyst sample with 2.35 wt.% followed by calcination at 400 °C resulted in an increase of 130 and 94% in the values of k20 °C– and k30 °C–, respectively. The doping process did not modify the activation energy of the catalyzed reaction but rather changed the concentration of the catalytic active constituents without changing their energetic nature.