(487s) Low Temperature CO Oxidation Using Platinum-Ceria On Silica Catalyst

CO is harmful to humans as well as the environment, and catalytic oxidation of CO to CO2 is an efficient way of removing CO. CO oxidation at low temperature still poses a major challenge, due to CO self-poisoning of the catalyst at ambient temperature. Although,supported gold catalysts are widely used for the low temperature CO oxidation, they lose their activity in the presence of moisture. A catalyst with active noble metal platinum and ceria as promoter, both supported in a nano-dispersed form on a high surface area silica support has been developed. The catalyst has a significant activity for CO oxidation even in the presence of moisture. The optimization of various catalyst preparation process parameters was carried out experimentally. The surface characterization was also carried out using CO chemisorption, N2 physisorption, and powder X-ray diffraction (XRD). The characterization results were correlated with the activity of the catalysts.

In a packed bed test, with a 4mm thick catalyst bed of 200 micron particle, the catalyst gave more than 99% conversion for more than six hours at 2500ppm CO and face velocity of 10cm/sec.

The activity of this catalyst can be attributed to the presence of ceria which acts as an oxygen reservoir. The proposed mechanism for CO oxidation is a redox mechanism which involves transfer of lattice oxygen from ceria to the adsorbed CO molecule on platinum. The resulting lattice oxygen vacancy is then immediately filled by oxygen from air.

This Pt-CeO2/SiO2 catalyst demonstrated a great potential for CO removal applications involving moisture. This catalyst can be used for air purification, as a cathode air filter for PEM fuel cells, also in emergency escape products for CO abatement.