Effect of Ag[2]O- and Mn[2]O[3]Doping of CuO/MgO-AI[2]O[3] on Its Surface and Catalytic Properties

ABSTRACT

Pure samples of CuO/MgO-Al[2]O[3] solids were prepared by wet impregnation method using a given weight of equimolar proportions of aluminum hydroxide and magnesium basic carbonate powders with calculated amounts of copper nitrate dissolved in the least amount of distilled water followed by drying and calcinations at 300 and 500°C. The doped samples were obtained by treating pure solids with a known weight of silver or manganese nitrate prior to impregnation with copper nitrate. The formulae of pure calcined solids were 0.05, 0.1 and 0.2 CuO/MgO-Al[2]O[3]. The dopant concentration was varied between 1-4 mol% Ag2[O] and 1-8 mol% Mn[2]O[3]. The results revealed that the specific surface areas of pure and doped solids decreased by increasing the calcination temperature from 300 to 500°C. The doping process resulted in a measurable increase in the BET-surface areas of all solids investigated. This process changed the catalytic activities of various solids in CO oxidation by O[2] and H[2]O[2] decomposition. Doping the solids investigated with both dopants brought about a considerable increase in the catalytic activity towards both H[2]O[2] decomposition and CO oxidation to an extent proportional to the amount of dopants added. The increase in the catalytic activity was, however, more pronounced for Ag[2]O-dopant. The increase in calcinations temperature from 300 to 500°C resulted in an increase in the catalytic activity of pure and doped solids. Activation energy calculations revealed that doping process did not modify the reaction mechanism of H[2]O[2] decomposition but rather changed the concentration of catalytically active sites without changing their energetic nature