Tailoring novel polymer/UTSA-16 hybrid aerogels for efficient CH4/CO2 separation

Abstract

A significant number of industrially relevant separation processes involves the removal of carbon dioxide (CO2), as the purification of natural gas (CO2/CH4 separation). In this scenario, the development of new adsorbents with a real technological future for CO2 separation, i.e with a high separation efficiency, good mechanical properties and easy to handle, is of primary importance. In the present work, novel composite monolithic aerogels containing the UTSA-16 metal organic framework as the active phase and porous crystalline polymers (namely syndiotactic polystyrene and polyphenyloxide) as binders were successfully synthesized and fully characterized. The adsorption capacity of such novel aerogels towards CO2 and CH4 was tested at low pressure and variable temperature, allowing the evaluation of their CO2/CH4 selectivity. Microcalorimetric experiments provided the CO2 interaction energy and disclosed possible deformation-relaxation phenomena involving the polymeric matrix during gas adsorption. The new composites retain a very high CO2 adsorption capacity compared to the pristine UTSA-16 (around 75% at 298 K and 1 bar) and have excellent CO2 capture performances in comparison to other types of supported/printed MOFs reported in the literature. The outstanding adsorption properties and the possibility to obtain monoliths with the desired size and shape and good mechanical stability make these new composites very good candidates for efficient CO2/CH4 separation processes.