Influence of Fe loadings on desulfurization performance of activated carbon treated by nitric acid

Abstract

A series of Fe supported on activated carbon treated by nitric acid are prepared by incipient wetness impregnation with ultrasonic assistance and characterized by N2 adsorption–desorption, X-ray diffraction, Fourier transform infrared spectrum and X-ray photoelectron spectroscopy. It has shown that Fe loadings significantly influence the desulfurization activity. Fe/NAC5 exhibits an excellent removal ability of SO2, corresponding to breakthrough sulfur capacity of 323 mg/g. With the increasing Fe loadings, the generated Fe3O4 and Fe2SiO4 increase, but Fe2(SO4)3 is observed after desulfurization. Fe/NAC1 has a Brunauer–Emmett–Teller (BET) surface area of 925 m2/g with micropore surface area of 843 m2/g and total pore volume of 0.562 cm3/g including a micropore volume of 0.300 cm3/g. With the increasing Fe loadings, BET surface area and micropore volume decrease, and those of Fe/NAC10 decrease to 706 m2/g and 0.249 cm3/g. The Fe loadings influence the pore-size distribution, and SO2 adsorption mainly reacts in micropores at about 0.70 nm. C=O and C–O are observed for all samples before SO2 removal. After desulfurization, the C–O stretching is still detected, but the C=O stretching vibration of carbonyl groups disappears. The stretching of S–O or S=O in sulfate is observed at 592 cm−1 for the used sample, proving that the existence of SO42−.