Surface and catalytic properties of CuO doped with Li2O and Al2O3

The effects of Li2O and Al2O3-doping of CuO on its surface and catalytic properties were investigated. The amounts of dopant were varied between 0.5 and 4 mol% and pure and variously doped samples were subjected to heat treatment at 300–700 °C. The techniques employed were XRD, nitrogen adsorption at −196 °C and catalytic decomposition of H2O2 at 30–50 °C. The results obtained revealed that Li2O-doping effected an increase in the particle size of CuO crystallites in the solids precalcined at 300–700 °C while Al2O3 exerted an opposite effect. The treatment of CuO with Li2O followed by precalcination at 300–700 °C effected a progressive decrease in its surface area to an extent proportional to its amount added. On the other hand, Al2O3-doping brought about a progressive increase in its BET-surface area. Both dopants brought about a dramatic progressive decrease in the catalytic activity of the treated catalysts. The induced decrease in the catalytic activity of CuO due to doping either with Al2O3 or Li2O has been attributed to solid–solid interactions between the dopant and CuO forming solid solutions and/or new compounds (copper aluminate and lithium cuprate). The doping process did not modify the activation energy of the catalyzed reaction but considerably decreased the concentration of catalytically active constituents without changing their energetic nature.