Study on the mechanism of iron-rich coal gasification slag on NO conversion in high temperature flue gas of cement kiln

•Coal gasification slag has higher denitrification rate at high temperature(700–1000 °C)•Oxygen concentration affects the adsorption and reaction of NO.•Iron groups as active components participate in the transformation of NO.•Fe3+ not only catalyzes the direct decomposition of NO, but also partially REDOX reaction with NO.