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The activity behavior for carbon monoxide oxidation of copper-chromium catalysts was studied by varying both the catalyst composition and pretreatments. Optimum pretreatment conditions were found by employing a commercial copper chromite catalyst. Supported and unsupported catalysts were prepared from metal nitrate solutions. An optimum metal concentration corresponding to CuCr204 was found for the unsupported catalysts. The presence of chromium was found to inhibit the reduction of the catalyst and to eliminate an activity induction period observed in copper. These results led to the postulation of a mechanism of electron transfer between copper and chromium, copper being the main active species. Copper-supported catalysts were more active than copper chromitesupported catalysts when metal concentrations were smaller than approximately 12%. At larger metal concentrations the supported copper chromite catalysts were more active. Chromium was also found to diminish an inhibition effect observed when water was introduced to the reaction mixture.

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