Study of carbon molecular sieve fibres by atmospheric TPD-MS of H2O, CO and CO2

Abstract

High-resolution temperature-programmed desorption mass spectrometry (TPD-MS) with a supersonic molecular beams (SMB) inlet system enables us to analyse quantitatively CO, CO₂ and water from various sites on carbon molecular sieve fibres (CMSF). Three water sites up to 350 °C are observed. The first main water site is from desorption of physically adsorbed water molecules on the surface oxides and inside the micropores. The other two sites result from dehydration and decomposition of surface oxides. The effects of relative humidity, oxide concentration and pore structure on adsorption of water on CMSF are studied. Gradual oxide group decomposition at low temperature, up to 250 °C, is monitored and the kinetics of surface oxide formation in air at room temperature is studied.