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

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 [Formula: see text].