Facile synthesis of cost-effective iron enhanced hetero-structure activated carbon/geopolymer composite catalyst for NH3-SCR: Insight into the role of iron species

A hetero-structure activated carbon/geopolymer composite catalyst enhanced with iron was fabricated via facile activated carbon embedded polymerization and controlled impregnation. Over the temperature window of 350-500 degrees C, the as-synthesized catalyst exhibited NO conversion greater than 96.5%, N-2 selectivity above 94% with stable durability, excellent SO2 and H2O resistance. The high NO conversion and N-2 selectivity may be associated with synergistic effects of extra-framework iron species in the geopolymer rings and excessive iron species agglomerated to form FeOx clusters on the activated carbon surface with enhanced redox capability. These are attached to the composite catalyst's unique hetero-structure, where the former provides active sites for lower temperature SCR while the latter provides reactivity at higher temperatures. The complex iron species in the catalyst are facile controllable through impregnation. This composite catalyst demonstrated a new approach for developing cost-effective NH3-SCR catalysts for practical implications.