The release of CO2 and CO during coal pyrolysis was investigated by using the density functional theory (DFT)of quantum chemistry

and benzoic acid and benzaldehyde were selected as coal-related oxygen-containing model compounds.By analyzing microscopic structures

thermodynamic and kinetic function changes

it could be concluded that the release processes of CO2 and CO during coal pyrolysis were related to the decarboxyl and decarbonyl reactions

respectively.The activation energy of decarbonyl reaction was larger than that of decarboxyl reaction

namely

removal of CO was more difficult than that of CO2.Decarboxyl and decarbonyl reactions were concerted processes via intramolecular hydrogen transfer

and cross-linking reactions were not directly related with decarboxylation and the release of CO2 during coal pyrolysis.