Erik J. Kielin

Comparison of the performance characteristics of Pt/SnOx and Au/MnOx catalysts for low-temperature CO oxidation

Abstract Platinized tin oxide (Pt/SnO x ) and gold supported on manganese oxide (Au/MnO x ) catalysts have been shown to be good CO oxidation catalysts at low temperatures (30–100°C). The performance of these catalysts has been compared by reacting mixtures of CO and OZ and He under similar conditions. The Au/MnO x catalyst is superior to Pt/SnO x catalysts with regard to both activity and decay characteristics under the conditions examined. As expected, Au/MnO x catalysts exhibit greater activity as the reaction gas mixture becomes more oxidizing.

Au/MnOx catalytic performance characteristics for low-temperature carbon monoxide oxidation

Manganese oxide-supported gold (Au/MnOx) catalysts have been prepared and tested for low-temperature (< 100°C) carbon monoxide oxidation in stoichiometric mixtures of carbon monoxide and oxygen containing no carbon dioxide in the feed gas. Even with no pretreatment these catalysts are superior to the best, pretreated platinized tin oxide (Pt/SnOx) catalysts under the conditions tested. The very small decay observed for Au/MnOx catalysts is mostly due to carbon dioxide retention. The optimum gold content has been determined to be 10 at.-% of the manganese content, and a lithium promotor results in improved catalytic behavior over K- or Na-promoted Au/MnOx catalysts for the conditions examined in this study.

INFLUENCE OF PROMOTERS ON THE PERFORMANCE OF AU/MNOX AND PT/SNOX/SIO2 LOW-TEMPERATURE CO OXIDATION CATALYSTS

The influence of promoters on Pt/SnOx/SiO2 and Au/MnOx low-temperature CO oxidation catalysts has been investigated under stoichiometric reaction conditions with no CO2 added to the feed gas. The performance of Pt/SnOx/SiO2 catalysts is improved significantly by the addition of 1 wt.% Fe but reduced by the addition of 5 wt.%Fe, 1 wt.% Sb, 5 wt.% Sb, 1 wt.% As, 5 wt.%As and 1.8 wt.% P. The performance of Au/MnOx is improved significantly by the addition of 1 at.% Ce but reduced by the addition of 1 at.% Co. For the catalysts and conditions examined, the Au/MnOx catalysts are superior to the Pt/SnOx/SiO2 catalysts with respect to both activity and decay characteristics.

Influence of an Fe promoter on silica-supported Pt/SnOx catalysts used for low-temperature CO oxidation

Silica-supported Pt/SnOx catalysts used for low-temperature CO oxidation have been prepared without and with an Fe promoter. Reaction studies demonstrate that the addition of the Fe promoter results in higher catalytic activity in the presence of 8 at% CO2 and a lower decay rate. Ion scattering spectroscopy (ISS) has been used to examine the outermost atomic layers of the promoted and nonpromoted catalysts before and after activation by a reductive pretreatment. The nonpromoted catalyst exhibits agglomeration of the platinized tin oxide film exposing the catalytically inactive silica support. This agglomeration does not occur when Fe is present, and a large catalytically active surface area is maintained during the reduction.