The evolution mechanism and energy conversion of volatile in low-rank coal with pyrolysis temperatures still remain uncertain. The experimental results on gas products and light tar pyrolyzed from Shenfu coal at various pyrolysis temperatures reflect the complex correlation between volatiles and coal structure affected by temperatures. Thermodynamic competitive evolution towards CO from oxygen-containing structures are analyzed by density functional theory. The formation mechanisms of polycyclic aromatic hydrocarbons (PAHs) from by-product cyclopentadienyl through Diels-Alder reaction and C–H β-scission are confirmed at the CBS-QB3//M06–2X/def2-TZVP level of theory. Kinetic rate coefficients of the rate-limiting step are computed. Thermodynamic and kinetic calculation results indicate that phenols pyrolysis have to cross a higher energy barrier. Moreover, cyclopentadienyl thermodynamically tends to form indene at 645 °C, while forming PAHs such as naphthalene, even fluorene, phenanthrene, and anthracene at 855 °C, which is consistent with the experimental results. A hydrogen-rich environment can kinetically facilitate the formation of PAHs.

在热解温度下低阶煤中挥发物的演化机理和能量转换仍然不确定。在不同的热解温度下，神府煤热解气产物和轻质焦油的实验结果反映了挥发物与煤结构受温度影响的复杂关系。通过密度泛函理论分析了从含氧结构向CO的热力学竞争演化。从副产物的环戊二烯基通过Diels-Alder反应和C-H的多环芳香烃（PAHs）的形成机制β在CBS-QB3 // M06-2X / def2-TZVP的理论水平上可以确定分裂。计算限速步骤的运动速率系数。热力学和动力学计算结果表明，酚类热解必须越过较高的能垒。此外，环戊二烯在645°C时热力学趋于形成茚，而在855°C时形成萘，甚至芴，菲和蒽等PAH，这与实验结果一致。富氢环境可以在动力学上促进PAH的形成。