Following changes in the porous texture of Nomex-derived activated carbon fibres with the molecular probe technique

Abstract

A series of Nomex-derived activated carbon fibres (ACFs) activated to different burn-offs (BOs) together with two series derived from the previous ACFs through chemical vapour deposition (CVD) treatments were used as adsorbents. The adsorption of molecules of different size, namely, dichloromethane, benzene, cyclohexane and carbon tetrachloride was used to monitor the textural evolution of microporous carbon fibres owing to these treatments. The analysis of the results showed that carbon deposit has taken place mainly at the entrance of the pores rather than in the interior. The information obtained about the porous structure and the molecular sieve behaviour of the samples in the different series was also useful for establishing the possible uses of these materials: thus, the obtained ACFs could be used for adsorbing volatile organic compounds (VOCs) in the field of environmental control while CVD-treated ACFs could be used as adsorbents for gas separations. In particular, the combined use of CH 2Cl 2 and C 6H 6 could be used to determine whether an adsorbent is a good carbon molecular sieve (CMS) for CO 2/CH 4 separation.