Performance and reaction mechanism of pyrite(FeS2)-based catalysts for CO reduction of SO2 to sulfur

In this study, an iron sulfide catalyst (PAC) was prepared to catalyze the reaction of CO reducing SO2 to sulfur to satisfy the high activity and stability of the catalyst, simplify the preparation process, and remove the sulfurization process. The physicochemical properties, reduction activity of the iron sulfide catalyst, and reaction mechanism of PAC-catalyzed CO reduction of SO2 were then systematically investigated. The results indicated that the optimum reaction conditions were a FeS2 proportion of 6 wt%, a reaction temperature of 550 degrees C, an airspeed of 5000 h(-1), and a CO/SO2 molar ratio of 2.6:1. Under these conditions, the SO2 conversion of PAC was stabilized at over 99.5% with a sulfur yield of up to 95.5% within 850 min without deactivating the active component or deteriorating the sulfate. This proves that PAC has very high catalytic activity and stability. The XRD and in situ XRD characterization showed that the reduced PAC contained primarily Fe7S8 in the sulfur phase, while no sulfate and sulfite were found. The reaction mechanism of the PAC-catalyzed CO reduction of SO2 can be divided into the FeS2 thermal decomposition mechanism and the COS intermediate product mechanism.