Adsorption of SO₂ onto oxidized and heat-treated activated carbon fibers (ACFs)

A series of activated carbon fibers (ACFs) and heat-treated oxidized ACFs prepared from phenolic fiber precursors have been studied to elucidate the role of pore size, pore surface chemistry and pore volume for the adsorption of SO₂ and its catalytic conversion to H₂SO₄.

For untreated ACFs, the initial rate of SO₂ adsorption from flue gas was shown to be inversely related to pore size. At longer times, the amount of SO₂ adsorbed from flue gas was dependent on both the pore size and pore volume.

Oxidation of the ACFs, using an aqueous oxidant, decreased their adsorption capacity for SO₂ from flue gas due to a decrease in pore volume and repulsion of the SO₂ from acidic surface groups. If these samples were heat-treated to desorb the oxygen containing function groups, the amount of SO₂ adsorption increased. This increase in adsorption capacity was directly correlated to the amount of CO₂ evolved during heat-treatment of the oxidized ACFs. The amount of SO₂ adsorbed for these samples was related to the pore size, pore surface chemistry and pore volume. This analysis is explained in more detail in this paper.