SEPARATION OF METHANE-NITROGEN MIXTURES BY PRESSURE SWING ADSORPTION USING A CARBON MOLECULAR-SIEVE

A 60%-40% and a 92%-8% methane-nitrogen mixture were separated in a tw o-bed pressure swing adsorption (PSA) unit using a carbon molecular si eve (CMS) adsorbent. The CMS adsorbent used in this separation is a du al resistance type comprising a barrier resistance on the crystal surf ace and diffusion resistance in the crystal interior. This dual resist ance is modelled using the linear driving force (LDF) PSA model. The p arameter Omega of the LDF model, which relates the theoretical and exp erimental results, was found to be significantly different from that f or conventional diffusion-controlled processes. This difference is att ributed to the presence of a barrier resistance in the CMS.