Differences in Macromolecular Structure Evolution during the Pyrolysis of Vitrinite and Inertinite Based on In Situ FTIR and XRD Measurements

An accurate understanding of molecular structure evolution during pyrolysis is essential for the clean utilization coal. In this study, middle-rank coal was taken as research subject, and vitrinite inertinite samples were stripped from using a hand picking sink–float separation process. situ Fourier transform infrared (FTIR) spectroscopy in X-ray diffraction (XRD) performed to compare macromolecular changes between pyrolysis. The results show that aromaticity (I), polycondensation degree aromatic rings (DOC), average lateral sizes (La) basic unit (BSU), stacking heights (Lc) BSU both increase continuously with increasing temperature. values these parameters are higher than those vitrinite, suggesting aromatization has always been vitrinite. FTIR shows could be divided into three stages based on temperature: 30–200 °C, 200–300 300–500 °C. content C–O–C, C=O, O–H groups, ring C=C gradually decreases, while CH2 aliphatic hydrocarbons increases 30 °C 200 stage mainly filled by synergistic effects groups. C–O–C decreases greatly. dominated condensation macromolecules. substituents system detach, leading an I DOC. From 1000 XRD reveal difference structural inertinite. arrangement layers tends ordered pyrolysis, whereas there no significant However, more compact addition, side chains stable