Fe-Cu-Al based FT catalyst and ZSM-5 cracking catalysts are employed in a consecutive dual bed reactor system for the production of C2-C4 olefins directly from synthesis gas. Effect of properties of FT and cracking catalysts on the CO conversion and product selectivity has been studied. The carburization and hydrogenation properties of catalysts related to chain propagation and termination reactions of FT catalyst are balanced by optimizing the K loading on Cu promoted Fe-Al FT catalyst. Alkalization with K resulted in the formation of Fe2O3 crystalline phase in FT catalyst, identified by XRD and this phenomenon has coincided with the suppression of chain termination reactions to yield enhanced C5+ hydrocarbons with minimum methane in synthesis gas conversion. Interestingly the olefinicity of light hydrocarbons is increased significantly after the K loading. The conceptualization of achieving higher C5+ olefinic products in FT followed by selective cracking of the C5+ into C2-C4 olefins has been realized by optimization of the properties of FT as well as ZSM-5 catalysts. The studies report an enthusiastic result that claims about 52% selectivity to C2-C4 hydrocarbon rich in olefins (77% selectivity).