苯甲酸和苯甲醛热解机理的量子化学研究

Pyrolysis mechanisms of benzoic acid and benzaldehyde based on quantum chemistry

采用量子化学密度泛函方法分析了煤相关含氧模型化合物苯甲酸和苯甲醛的热解机理。微观结构分析、热力学和动力学分析结果表明:煤热解过程中CO2和CO的逸出分别与脱羧和脱羰反应相对应,而脱羰反应活化能较大,即CO的脱除较CO2难于发生;脱羧和脱羰基反应为分子内氢转移协同过程,煤热解脱羧放出CO2与交联反应的发生无直接关系。

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.