Image Number 6 for United States Patent #6548446.
A selective catalytic material is used in a method for selective oxidation of carbon monoxide in the presence of hydrocarbons and contains rhodium and a bismuth component either as a supported catalytic material dispersed on a refractory inorganic oxide support or as an unsupported catalytic material prepared, for example, by co-precipitation from a solution containing dissolved bismuth and rhodium salts. The bismuth and rhodium components are present in amounts that provide an atomic ratio of bismuth to rhodium in the range of from about 0.1:1 to 10:1, e.g., from about 1:1 to 2.5:1. The selective catalytic material is contacted under oxidizing conditions with a gas stream containing carbon monoxide and hydrocarbons. The selective catalytic material (24a) may be disposed on a sensor (24) disposed within a conduit (18) downstream of a conventional treatment catalyst (16) to evaluate the performance of the latter by measuring the extent of carbon monoxide oxidation catalyzed by the selective catalytic material (24a) in the treated gas.