Highly efficient Fe-Cu/CL catalysts based on low-cost clay minerals for NH3-SCR of NOx at low temperature

One of the main challenges for NH 3 -SCR of NOx at low temperatures is developing a catalyst with exceptional low-temperature catalytic activity. Herein, four kinds of clay minerals including halloysite (Hte), Ca-montmorillonite (Ca-Mte), chlorite (Cte), and Na-montmorillonite (Na-Mte) were used as supports and impregnated with Fe and Cu to synthesize Fe-Cu/Hte, Fe-Cu/Ca-Mte, Fe-Cu/Cte, and Fe-Cu/Na-Mte catalysts, respectively. Within a temperature range of 180–240 °C, the resultant Fe-Cu/Hte catalyst produced more than 98 % NOx conversion and demonstrated the best low-temperature NH 3 -SCR catalytic performance. The characterization results indicated that the weakened crystallinity of active species, high ratios of Fe 3+ /Fe and Cu + /Cu, and more surface absorbed oxygen species, as well as excellent low-temperature redox ability and surface acidity all contributed to its outstanding low-temperature catalytic activity. The in situ DRIFT study at 240 ℃ showed that two forms of the Eley-Rideal (E-R) mechanism existed on the Fe-Cu/Hte and Fe-Cu/Cte catalysts, while the E-R and Langmuir-Hinshelwood (L-H) processes were both involved over the Fe-Cu/Ca-Mte and Fe-Cu/Na-Mte catalysts.