Controlling NOx emissions is important for our health and the environment. Selective catalytic reduction (SCR) using carbon monoxide (CO) is an effective way to reduce NOx in flue gas cleaning. Different catalysts, like metal oxides, can help with this process. The research looked at how well these catalysts work in reducing NOx with CO. They also studied how oxygen, water steam, and sulfur dioxide in exhaust gases affect the process. The findings show that CO-SCR is a simple and cost-effective method for reducing harmful NOx emissions.