Enhanced SO2 resistance of NiFe/CeO2 catalyst by adding WS2 for CO-assisted selective catalytic reduction reaction

Selective catalytic reduction (SCR) is an effective NOx reduction method. Recently, research has been conducted on simultaneously removing NOx and CO using passive SCR technology that consumes CO gas that is normally generated in industrial combustion processes (designated as CO-SCR). SO2 gas in industrial flue gas can compete with NOx and CO, leading to catalyst deactivation and a shortened lifespan. Catalysts with resistance to the sulfur present in industrial processes are crucial for CO-SCR. Therefore, this study aimed to develope a catalyst resistant to the SO2 present in exhaust gas; specifically, WS2 which has excellent chemical stability, was added to a transition metal-based catalyst NiFe/CeO2 and the CO-SCR activity of the unmodified and WS2-incorporated catalysts (NiFe/CeO2 and NiFe/WS2-CeO2, respectively) were examined. NiFe/WS2-CeO2 (1 wt% WS2 content) exhibited a high NOx conversion rate of more than 80% in a sulfur atmosphere. The addition of WS2 to NiFe/CeO2 improved its CO adsorption capacity and catalytic reduction properties by 1.63 and 1.28 times, respectively, thereby promoting the catalytic performance. Fourier-transform infrared analysis revealed that NiFe/WS2-CeO2 was more resistant to sulfur poisoning than NiFe/CeO2. These findings can be leveraged to develop sulfur-resistant catalysts for eliminating NOx and CO from industrial flue gas.