Initial Mechanisms for an Overall Behavior of Lignin Pyrolysis through Large-Scale ReaxFF Molecular Dynamics Simulations

By Tingting Zhang, Xiaoxia Li, Xianjie Qiao, Mo Zheng, Li Guo, Wen-li Song, Weigang Lin. 2016

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Initial reaction mechanisms of lignin pyrolysis were studied by large-scale ReaxFF molecular dynamics simulations (ReaxFF MD) facilitated by the first GPU-enabled code (GMD-Reax) and the unique reaction analysis tool (VARxMD). Simulations were performed over wide temperature ranges both for heat up at 300–2100 K and for NVT at 500–2100 K with a large lignin model, which contained 15920 atoms and was constructed based on Adler’s softwood lignin model. By utilizing the relatively continuous observation for pyrolysate evolution in slow heat up simulations, three stages for lignin pyrolysis are proposed by pyrolysate fractions. The underlying mechanisms for the three stages are revealed by analyzing the species structure evolution and the reactions of linkages, aryl units, propyl chains, and methoxy substituents. Stage I is characterized with the complete decomposition of source lignin molecules at low temperatures dominated by breaking of α-O-4 and β-O-4 linkages. The temperature in stage II is relatively hi...

Subfields: Biomedical Engineering, Biotechnology

View Paper: https://www.semanticscholar.org/paper/bd371d3c5b1fe6ed32fe71dfc7eb4729538dc827