Surface characteristics and carbon dioxide capture characteristics of oxyfluorinated carbon molecular sieves

A carbon molecular sieve (CMS) was modified through oxyfluorination to investigate its carbon dioxide (CO2) adsorption characteristics. The oxyfluorination was performed at various F2/O2 ratios at room temperature. The surface chemical properties and pore size distributions on the CMSs were altered by oxyfluorination and analyzed through XPS and isothermal gas adsorption. The CO2 adsorption capacity on the oxyfluorinated CMSs was different from that of unmodified CMSs due to changes in the functional groups on the carbon surface. The CO2 uptake at 273 K was unchanged compared with untreated CMS and measured approximately 2.5 mmol/g. However, at 298 K, the CO2 adsorption capacity increased from 1.61 mmol/g for an unmodified CMS to 2.07 mmol/g for the oxyfluorinated CMS. We suggest that introduced oxygen and fluorine functional groups on carbon surface by oxyfluorination increased basicity on carbon surface. Consequently, interaction energy between functional groups and CO2 molecular are increased at room temperature and it contributed to enhance CO2 adsorption amount.

To investigate the properties of CO2 capture, carbon materials with enhanced adsorption performance were prepared by oxyfluorination using physical treatment at various reaction conditions.Figure optionsDownload as PowerPoint slideHighlights
► To investigate the properties of CO2 uptake, surface-treated CMSs were prepared by oxyfluorination.
► The CO2 uptake capacities of the modified CMSs increased compared with the unmodified CMS.
► Interactions between functional groups (consisting of F and O atoms) and CO2 gas were noted.
► The CO2-adsorption capacity of 2.0 mmol/g obtained for the oxyfluorinated CMS.