High-temperature rapid pyrolysis affects the reduction of harmful NO gas on semi-coke char. The study found that pyrolysis at around 1100 °C helps reduce NO, but too high or low temperatures are not good. The char formed at 1100 °C has lower activation energy for NO reduction. Adding CO helps reduce NO even more, while adding oxygen makes it harder to reduce NO. This research shows that semi-coke can be used as a fuel or reducing agent with the right pyrolysis conditions.