OXIDATION OF CARBON MONOXIDE USING SILVER CATALYST ON DIFFERENT OXIDE SUPPORTS

Abstract

Over the course of past 60 years there is an exponential growth in the population of automobiles across the world. Most of these vehicles use petroleum derived fuels as the source of energy in their engines. Due to incompete combustion of these fuels, the exhaust contains various pollutants like CO, HC and NON. These pollutants can be regulated before entering into environment either by engine modification, fuel modification or by exhaust modification. Catalytic converters, assembled in tail pipe of the automobile, regulate the concentration of pollutants in the exhaust. In current practice noble metals like Pt, Au is used as catalysts in the catalytic converter. Since the availability and cost of these noble metals do not permit and the costs of these noble metals do not permit them to be used for a long time to come, so the development of equivalent catalysts which are cheaper and easily available is desirable. Silver is a precious metal cheaper than gold and platinum. Ag is a very good oxidation catalyst, but in case of CO oxidation the adsorption of CO on Ag is very poor. By supporting the silver metal on various oxides like TiO2, CeO2, A1203, ZnO2 and Zr02 we can increase the catalytic activity of Ag catalyst for the oxidation of CO. Several catalysts were prepared by supporting the different percentages of silver on various oxide supports like CeO2, Zr02 and TiO2 using co precipitation and dry mixing methods and calcined at 450°C for 8h. The characterizations of catalysts were done by using XRD, TGA and SEM. The catalytic activity tests were performed in a capillary fixed bed tubular reactor. These tests were conducted in the temperature range of 50-300°C at a constant space velocity of 1W450h-I during all the tests. The exhaust gases from the reactor were analyzed by using a gas chromatograph integrated with the computer. From the results, the Ag/CeO2 catalysts showing best performance in comparision with the silver catalysts supported on other oxides. Among the ceria supported silver catalysts, 10% Ag /Ce02. showing very good catalytic activity for the CO oxidation on which the 100% of CO is obtained at 135°C.