The adsorption of hexane over MCM-41 type materials

Hexane adsorption on mesoporous silicas has been studied in the temperature range 260 up to 350 K. Classical models for the textural characterization of MCM-41 by hexane were employed and confirmed analyses using nitrogen as a probe whereas energetic parameters such as CBET were found to be dramatically low. This has been discussed in terms of balance of wall/adsorptive interaction and dispersive interaction leading to unusual adsorption processes, capillary condensation commencing before the monolayer completion. Isosteric heats of adsorption could be derived. Specific confinement effects could be evidenced and the heat of adsorption was found to be strongly dependent on the pore size.