Factors Influencing Hydrogenation and Decomposition of H₂O₂ Over Pd–Au Catalysts Supported on Activated Carbon Cloth (ACC)

Abstract

The bimetallic Pd–Au catalysts were prepared by simultaneous co-impregnation or consequent impregnation of supports by palladium and gold precursors. The catalytic reactions were performed batch-wise in a Parr stainless steel autoclave and methanol (220 ml) was used as solvent. A series of experiments were conducted to study effects of several variables and conditions on the final H₂O₂ destruction activity of the catalysts. The factors studied where : the surface chemistry of the support, the amount and ratio of palladium and gold, the catalyst preparation method, the heat treatment of the catalysts in H₂ and air, the reaction medium, and reaction temperature. As a conclusion, H₂O₂ destruction activities of the catalysts were strongly affected by the surface chemistry of the support and the amount and ratio of palladium and gold. Bimetallic catalysts prepared by co-impregnation of Pd and Au were less destructive than the corresponding ones prepared by consequent impregnation. The catalysts supported on activated carbon cloth (ACC) oxidized by nitric acid were considerably less destructive than the corresponding ones on non-oxidized ACC. H₂O₂ destruction activity of the catalysts on oxidized ACC were highly affected by the heat treatment in H₂ and air at different temperatures. Using water instead of methanol as reaction medium substantially speeded up H₂O₂ destruction. Furthermore, increasing the reaction temperature accelerated destruction of H₂O₂. Catalytic destruction of H₂O₂ via its decomposition was considerably low as compared to hydrogenation.