Activated carbon fibers prepared from quinoline and isoquinoline pitches

Nitrogen enriched activated carbon fibers(ACFs) were prepared from isotropic quinoline and isoquinoline pitches produced by the catalytic action of HF/BF₃ through spinning, stabilization, carbonization, and oxidative activation. The pitches exhibited excellent spinnability, and the resultant fibers had mechanical properties comparable to those of commercial fibers. The surface areas and nitrogen contents of the ACFs, obtained hereby were 740-860 m²/g and 4-5.6%, respectively, at around 50 wt% of burn-off. FT-IR and XPS analyses identified the surface oxygen and nitrogen functional groups on the stabilized and activated fibers. The ACFs from isoquinoline pitch(IQP-ACF) exhibited higher basicity(1.3 meq/g) than commercial ACFs of similar surface areas(0.68 and 0.25 meq/g for PAN(FE-300) and coal tar pitch(OG-8A) based ACFs, respectively) due to a higher basic nitrogen content on the surface. The activation appears to expose basic nitrogen atoms, which were located under the surface. The basicity of ACF from quinoline pitch(QP-ACF) was much lower than that of IQP-ACF, however, QP-ACF adsorbed 74 mg/g of SO₂. which was 1.4 and 2.3 times higher than that over FE-300 and OG-8A. In contrast, IQP-ACFs showed less adsorption of SO₂ than that of QP-ACF and FE-300, but more than that of OG-8A. Oxidation activity of ACF surface may participate in the adsorpton of SO₂ in the form of SO₃ or H₂SO₄. The oxygen functional groups under the influence of neighboring nitrogen atoms may be the active sites for the oxidative adsorption.