Carbon molecular sieve cloths prepared by chemical vapour deposition of methane for separation of gas mixtures

Microporous carbon molecular sieves for separating gaseous mixtures have been prepared through chemical vapour deposition (CVD) of methane on activated carbon cloth obtained from Nomex aramid fibre. The activated carbon fibres were subjected to CVD of methane for different periods of time. The textural characterization of the resulting materials was assessed by physical adsorption of gases (N2 and CO2) and vapours (dichloromethane, benzene and cyclohexane) as well as immersion calorimetry into the same liquids. A direct visualization of the changes induced by CVD on the micropore mouth structure of the activated carbon cloth was provided by scanning tunnelling microscopy (STM). The validity of the materials for separating CO2/CH4 and O2/N2 was tested by assessing the kinetics of adsorption of the corresponding gases. Carbon molecular sieves with good selectivity for CO2/CH4 separation and showing acceptable CO2 adsorption capacity were obtained.