Inhibition mechanism between sodium (Na3AlF6) and sulfur on coke reactivity was investigated by simulating petroleum coke with low-impurity pitch coke and by impurity doping.The mechanism was discussed by scanning electron microscopy,energy-dispersive spectrometry,and X-ray powder diffraction.Results show that Na effectively inhibited S catalysis during carbon-air/CO2 reactions,and S inhibited the catalysis of Na during carbon-air reaction to a certain extent.A stable structure with a Na-to-S atomic ratio of 1.4 and a cyclic reaction system ofNa2SO3→ Na2S→ Na2COy→.Na2SO3 were likely the keys to producing this mutual inhibition.