Mechanism of SO₂ adsorption and desorption on commercial activated coke

We used commercial activated coke (AC) as adsorbent and fixed-bed, FTIR, N₂ adsorption, ion chromatograph as research methods to study the SO₂ removal mechanism in the presence of O₂ and H₂O and adsorbate (H₂SO₄) desorption mechanism by combined regeneration. The results showed that AC saturation sulfur retention (52.6 mg/g) in SO₂+O₂+H₂O atmosphere was 4.6 times as much as that (11.4 mg/g) in SO₂+O₂ atmosphere and 5.0 times as much as that (10.6 mg/g) in SO₂+O₂ atmosphere at 90 °C. O₂ and H₂O were necessary in AC desulfurization process. Reaction of SO₃ and H₂O (g) and condensation of sulfuric acid vapor were the dynamic of AC desulfurization process. Water vapor blowing in combined regeneration inhibited the reaction between H₂SO₄ and carbon, and consequently reduced the chemical lost of carbon. AC cumulative quality loss (53.6%) of five-times in C-R was still less than that (62.4%) of three-times in H-R. Water vapor blowing inhibited reactivation effect, as a result reducing the changes of AC pore structure and surface functional groups. Adsorbate H₂SO₄ generated in desulfurization evaporated to sulfuric acid vapor due to the high temperature in regeneration and was carried out by water vapor.