Influence of Calcination Temperatures on the Desulfurization Performance of Fe Supported Activated Carbons Treated by HNO3

Fe supported on activated carbons treated by HNO 3 (Fe/NAC) was prepared using the incipient wetness method with ultrasonic-assisted oscillation and calcined at different temperatures. The physical and chemical properties were studied using FTIR, XPS, XRD and H 2 -TPR, and SO 2 removal ability of Fe/NAC was also evaluated at a fixed bed. The results showed that α-Fe 2 O 3 and small Fe 3 O 4 coexist in Fe/NAC-500, while catalysts calcined at 700 °C only possess Fe 3 O 4 . Fe 3 O 4 with small Fe 2 SiO 4 is observed for Fe/NAC-900, but Fe 2 SiO 4 and Fe 0 are detected in Fe/NAC-1000, indicating that the interactions between Fe precursor and activated carbons are very complex, and C atoms may take part in the reduction of iron oxides. The relative content of C–C and C–O decreases first and then increases when calcination temperatures increase from 500 to 1000 °C, but that of C═O and O═C—OH has a contrary trend, suggesting that calcination temperatures influence the formation of functional groups. Fe/NAC-900 shows the best activity and has a sulfur capacity of 322 mg/g, which is related closely to O═C—OH and good crystallinity of Fe 3 O 4 . Fe 3 O 4 is the main active phase in the SO 2 removal process. After desulfurization, O═C—OH, α-Fe 2 O 3, Fe 3 O 4, and Fe 0 disappear, and Fe 2 (SO 4 ) 3 is observed, leading to the decrease of SO 2 removal ability.