Shell has developed a low temperature DENOX system which consists of a high activity granular SCR catalyst and a low pressure drop lateral flow reactor. The Shell DENOX system achieves more than 95% NOx reduction with minimal ammonia slip. The Shell DENOX system can be installed at the low temperature end of the flue gas stream and, therefore, represents a more economical solution compared to retrofitting of honeycomb type catalysts in the high temperature window.