Pd(II)–Cu(II) compositions fixed on dispersed silica from ammonia solutions for carbon monoxide oxidation with air oxygen

Abstract

The samples of dispersed silica, tripoli from the Konoplyansky deposit, were used in this work. Pd(II)–Cu(II) compounds fixed on dispersed silica for the oxidation of carbon monoxide with air oxygen were obtained by impregnation of the carrier, which was previously boiled in distilled water for one hour, through NH3-coordination in the presence of ethyl alcohol, followed by maturation of the catalyst at 200C for 20 hours and drying at 3000C for 4 hours. The initial and chemically modified samples of tripoli were characterized by X-ray phase analysis, IR-spectral and thermogravimetric research methods and tested in the reaction of low-temperature oxidation of carbon monoxide with oxygen. The degree of CO conversion in the stationary mode was used to estimate the activity of the catalyst. It was established that the activity of copper-palladium catalysts is significantly affected by the method of catalyst preparation, namely: the sequence of mixing the starting solutions, the drying temperature, and the content of the catalyst components. The catalyst with the highest activity contained all the components, such as K2PdCl4, Cu(NO3)2, NH4OH, KBr, and Ñ2Í5ÎÍ, mixed beforehand in the specified sequence. It provides air purification from CO to a concentration that is 5 times lower than the maximum permissible concentration for the working area (MPCCO=20 mg/m3). The degree of CO oxidation reaches 98.6%. With other variations of the method of the catalyst preparation, the samples show much lower activity, which indicates the formation of surface complexes of different composition, responsible for the oxidation of carbon monoxide by air oxygen.