Study on Chemical Bond Dissociation and the Removal of Oxygen-Containing Functional Groups of Low-Rank Coal during Hydrothermal Carbonization: DFT Calculations
Han Dang, Guangwei Wang, Chunmei Yu, Xiaojun Ning, Jianliang Zhang, Nan Zhang, Yi Gao, Runsheng Xu, Chuan Wang
Abstract
with the Mayer bond order (MBO) greater than 1 also contains certain π bond characteristics. The lignite van der Waals (vdW) surface electrostatic potential (ESP) was constructed and visualized, and the results showed that the oxygen-containing functional groups mainly contributed to the area with a large absolute ESP. Finally, weak interactions between water molecules and lignite at different sites were described by independent gradient model (IGM) analysis. Models A, B, and E formed weak interactions with the hydrogen bond as the main force; model E showed the weakest hydrogen bond, while model C showed van der Waals interaction as the dominant force. In addition, some steric effect was also observed in model D.