Oxidative fixation of SO₂ into aqueous H₂SO₄ over a pitch-based active carbon fiber above room temperature

Oxidative fixation of SO₂ into aqueous H₂SO₄ was examined at 50-70 °C over a pitch-based active carbon fiber (ACF) of large surface area. A higher temperature was found to require higher humidity and a longer contact time for the complete removal of SO₂ at the stationary state. Smaller adsorption of SO₂ and less condensed water on the ACF make it difficult to fix SO₂ on the ACF and to elute aqueous H₂SO₄ continuously from the ACF, as revealed by the adsorbed SO₂ on ACF and the eluted aqueous H₂SO₄ from the bed. Among the ACFs of different calcination temperatures, a particular ACF of the largest surface area calcined at 1100 °C showed the largest activity regardless of the reaction temperatures and humidity, indicating a major influence of the number of active sites. The hydrophilicity of the ACF has little influence on condensing water on the ACF above room temperature.