Chemical structures of coal lithotypes before and after CO2 adsorption as investigated by advanced solid-state 13C nuclear magnetic resonance spectroscopy

► We characterize four lithotypes (vitrain, bright clarain, clarain, and fusain) by NMR. ► We examine four lithotypes after exposure to high-pressure CO2 adsorption isotherm. ► Fusain is distinct from other three lithotypes with its highest aromatics. ► Structural changes after CO2 adsorption suggest chemical CO2-coal interactions. ► The lithotypes respond differently to high-pressure CO2 adsorption.