Nano- and micro-iron oxide catalysts for controlling the emission of carbon monoxide and methane

Two promising catalysts for the low-temperature oxidation of carbon monoxide and methane were investigated to determine their characteristics and possible usefulness in pollution control systems. Although both materials consisted of ultra-fine particles of ferric oxide, there was a significant difference in the average particle size and surface area of the materials. One of the materials, NANOCAT® superfine iron oxide, consisted of particles with an average size of 3 nm and a specific surface area of 250 m2/g. The other material, Fe2O3-PVS, consisted of particles with an average size of 300 nm and a specific surface area of 4 m2/g. Both materials proved effective for catalyzing the oxidation of either CO or CH4 at temperatures far below the normal flame temperature of these gases. This was determined by observing the conversion of CO or CH4 to CO2 in the presence of excess oxygen at different temperatures in a small tubular, flow reactor packed with a catalyst. The conversion was also used as a basis for determining the catalytic activity of the two catalysts at different temperatures, reactant concentrations, and space–times. The results showed that the NANOCAT® had the greatest catalytic activity for a given mass of catalyst which was probably due to its greater specific surface area.