Processes for preparing a composition comprising (i) an acidic metal oxide containing substantially no zeolite, (ii) an alkali metal, alkaline earth metal, and mixtures thereof, and (iii) an oxygen storage component are disclosed. Preferably, the process comprise forming a single slurry of components (i) (iii), spray drying and calcining to obtain metal oxide particles comprising components (i) (iii). Preferably, the slurry comprise a base peptized acidic metal oxide containing slurry wherein the component (ii) is provided in the slurry as a metal of the base. Compositions prepared are impregnated with a noble metal to provide compositions useful to reduce gas phase reduced nitrogen species and NO.sub.x in an effluent off gas of a fluid catalytic cracking regenerator.