Adsorption and hydrophobic properties of mesostructured MCM-41 and SBA-15 materials for volatile organic compound removal

The adsorption properties of different ordered mesoporous materials, for the removal of volatile organic compounds (VOCs) in air, have been studied by means of a thermal programmed desorption technique. Toluene, isopentane, and water have been used as adsorbates, whereas a variety of mesostructured materials (MCM-41, Al-MCM-41, and SBA-15) have been selected as adsorbents. As expected, Al-MCM-41 is a hydrophilic material, adsorbing high amounts of water due to the presence of acid sites. On the contrary, pure silica MCM-41 and SBA-15 samples exhibit hydrophobic properties, and they are capable of adsorbing toluene and isopentane in significant amounts. Among these materials, MCM-41 prepared by a sol-gel route [MCM-41-(H-sg)] presents the best combination of hydrophobic character and hydrocarbon adsorption, being a potentially interesting adsorbent for the removal of VOCs from humid gases. This behavior has been related to the high structural disorder and low condensation degree of the silica walls present in this material.