The invention includes a process for reducing the amount of NOx discharged to atmosphere from a FCC unit, having a regenerator and a means for collecting and supporting catalyst particles. The process comprises adding a catalyst to the regenerator flue gas prior to entering the collecting means and precipitating the catalyst in the collecting means to form a catalyst bed. Ammonia or ammonia precursor is added to the flue gas prior to and/or within the collecting means. The flue gas NOx is reacted with the ammonia or ammonia precursor at 200° C. to 800° C. in the presence of the catalyst bed to reduce the NOx amount, and the flue gas containing a reduced amount of NOx is discharged to atmosphere. The catalyst is one or more supported transition or lanthanide metal catalysts. The process can also be utilized in any combustion process.