High-temperature treatment effect of microporous carbon on ordered structure of confined SO₂

The X-ray diffraction (XRD) of SO₂ molecules adsorbed in micropores of activated carbon fiber (ACF) was measured at 303 K. Effect of pore width and high-temperature treatment (HTT) of ACF on the XRD of SO₂ in micropores were examined. The HTT gave rise to a more dipole-oriented structure of SO₂ molecules in micropores of 1.1 nm width, whereas the opposite effect was observed in micropores of 0.7 nm. The intensified image potential of an SO₂ molecule for the heat-treated graphitic pore wall should stabilize the dipole-oriented structure in the case of 1.1 nm micropores, while the heat-treatment provides defective structures in the narrow micropore system. The presence of O₂ stabilized the dipole-oriented structure of SO₂ molecules in the micropore.