Abstract
Washcoat-free catalysts capable of operation in high-temperature combustion exhaust streams were produced via anodically oxidized stainless steel mesh catalysts supports with platinum and palladium as the catalytically active species. Except for the least aggressive anodic treatment, this methodology created catalysts that were more active and stable than catalysts prepared without anodic oxidation. In general, increasing the current during anodic oxidation resulted in increased activity at high temperatures, likely by improving surface roughening, which reduced the impact of steam-enhanced sintering. Treatment with acid with relative medium acidity resulted in catalysts with superior activity and stability. This increase in activity at moderate current has been attributed to increased metal uptake and in the platinum to palladium ratio, which increased to nearly a 1:1 ratio for the most active catalysts, as well more oxide growth relative to surface dissolution. Also, the most active catalyst displayed excellent stability during an extended 100-h time-on-stream test.