Carbon dioxide adsorption over amine modified silica: Effect of amine basicity and entropy factor on isosteric heats of adsorption

•SBA-15 porous silica was modified by amine ligands with one, two and three amine centres.•Carbon dioxide adsorption at 273, 293, 313 and 333 K were measured.•Based on the CO2 adsorption isotherms, isosteric heats of adsorption were calculated.•Correlation between isosteric heats of adsorption and basicity of amine ligands was found.