Catalytic Combustion Of CO And CH₄over Mesoporous Alumina Supported Catalysts

As we know, carbon monoxide （CO） is one of the pollutants produced inthe process of combustion, which widely distribute in the atmosphere. COmainly come from the combustion of fossil fuels in the internal combustionengine, power plant, industry and domestic life if it is not well treated anddirectly discharged into the atmosphere, it will cause the environmentalpollution, which is harmful to the health and safety of human beings. So it isnecessary to reduce the level of CO.Methane is the main component of biogas and natural gas, which isbroadly distributing in the nature. It can be used as a gas fuel and manufactureof hydrogen, carbon black and other raw materials. Because of low carboncontent and high calorific value, methane can reduce the emissions of carbondioxide in the atmosphere; it can be used as a fuel alternative energy whichhas great potential value in the application and environment. The catalyticcombustion is the efficient way for the combustion of methane.Mesoporous alumina has large specific surface area, regular porestructure and good hydrothermal stability, it has good prospect of applicationin catalysts. In recent years, it is hot in research which preparing highly active catalysts by loading the transition metals and their oxides on the mesoporousalumina.A series of mesoporous aluminas was prepared by means of solventevaporation （SE）, soft template （ST）, Precipitation （PR）, and Ceramic （CE）methods. These aluminas were used as supports of the active cobalt and ironfor the catalytic combustion of carbon monoxide and methane. The materialswere characterized by X-ray diffraction （XRD）, N₂adsorption-desorption（BET）, transmission electron microscope （TEM）, H₂-temperature programmedreduction （TPR）, X-ray photoelectron spectroscope （XPS）. The Co/aluminacatalysts were then submitted to activity tests in the CO+O2â†'CO2reaction,which was carried out in a fix-bed reactor under a gas hourly space velocity of30000h-1. The selection of supports played an important role in thedevelopment of active catalysts. The best performance of CO oxidation wasachieved over Co/Al₂O₃employing Al₂O₃of SE method （CO conversionreached100%at350℃）. This could attribute to the mesoporous structure, thesuperhigh BET surface area and the abundance of highly active Co₃O₄oversurface. The Fe/alumina catalysts were then submitted to activity tests formethane combustion, the best performance was achieved over Fe/Al₂O₃employing Al₂O₃prepared by ST method （CH₄conversion reached>90%at600℃）. This could attribute to the high BET surface area and the high valencestate of iron （Fe₂O₃） over surface.