Catalyst synthesis for the selective carbonmonoxide oxidation from hydrogen rich fuel

Silver-cobalt and silver-manganese oxides were prepared by co precipitation method at several metal/metal oxide molar ratio and by different rates of precipitation. The catalyst was calcined with air at various calcination temperature and calcination time. Catalysts were characterised by BET method for the surface area; by XRD to determine the particle size and by TGA to see the thermal stability. The CO oxidation studies and the selective CO oxidation studies were carried out in a micro reactor using reaction gas mixture of 1% CO in air for CO oxidation reaction and 1% CO, 2% 02, 84% H2 and remaining He for the selective CO oxidation reaction. Different concentration of CO2 were added to reactant gas in order to determine the effect of CO2. For the water vapor effect, reaction gases were passed through the humidifier. It was obtained that when the calcination temperature increased, metal oxide base was decomposed to metallic phase. When the calcination temperature increased, surface area of the catalysts were decreased. After CO oxidation reaction, it was obtained that the catalysts calcined in air at 200°C for 3 hours are the most active catalysts. The 50/50 Ag/Co catalyst prepared by slow precipitation calcined in air at 200°C for 3hours gives 50%IV conversion at T<50°C; the 50/50 Ag/Co catalyst prepared by opposite slow precipitation calcined in air at 200°C for 3hours gave 50% conversion at T<78°C and the 50/50 Ag/Mn catalyst prepared by opposite slow precipitation calcined in air at 200°C for 3hours gave 50% conversion at T<30°C. All of the catalyst gave 100% conversion above 130°C. The performance of the catalyst was lowered significantly by the addition of CO2 and CO2 with water vapor. Water vapor appeared to condense in the pores of the catalyst and this physically blocked the pores. CO2 and water vapor were adsorbed weakly on the catalyst surface and thus physically blocked access to CO on oxygen. The results of the activity of catalyst for CO oxidation in the slow and opposite slow precipitation gave the 90% conversion at 180°C and the 50/50 Ag/Mn catalyst prepared by the opposite slow precipitation gave only 20% conversion between 80°C-200°C when the feed composition is 1 % CO, 2% O2, 84% H2 and the remaining He. The conversion of CO was significantly decreased when the CO2 was added to the feed. The 50/50 Ag/Co catalyst prepared by the opposite slow precipitation gave 30% conversion at 170°C and the 50/50 Ag/Mn catalyst prepared by the opposite slow precipitation gave only 15% conversion between 80°C-200°C when the feed composition was 1% CO, 1% 02, 23% C02, 65% H2 and the rest He. Science code :603.02.01 Keywords : Carbon monoxide oxidation, Hydrogen, silver, metal oxide catalysts