Carbon monoxide combustion and promoter therefor

The present invention provides novel catalyst products for promoting the combustion of carbon monoxide, particu- lady in catalytic cracking units, especially FCC units. The Improved products of the invention comprise one or more catalytically active metals selected from the group consisting of palladium or mixtures of palladium and at least one other precious metal on a porous silica-alumina support obtained by leaching sufficient silica from shaped partcles of calcined clay with causitc solution to impart porosity to the particles. The calcined clay from which silica is leached to impart porosity is preferably kaolin clay that has been calcined at a temperature and for a time sufficient to substantially convert the clay into mullite and silica, whereby the support particles consist essentially of mullite crystals.