Initial pyrolysis behavior and char formation characteristics of lignin based on reactive molecular dynamics simulation

Y Sakurai and R Kameda and M Hiratsuka and J Kobayashi, CHEMICAL ENGINEERING SCIENCE, 310, 121531 (2025).

DOI: 10.1016/j.ces.2025.121531

The initial pyrolysis behavior and char formation process of lignin were studied at the molecular level using reactive molecular dynamics simulations (ReaxFF MD simulations). The Adler lignin model, assuming softwood lignin as the model lignin molecule, was employed. The initial pyrolysis behavior was analyzed at seven simulation temperatures between 873 and 2873 K for a period of 500 ps. As pyrolysis progressed, gas yield increased monotonically, whereas tar yield increased up to 2073 K, then decreased at higher temperatures. A trade-off between the char and tar yields was observed. The H/C and O/C ratios of the char decreased with increasing temperature, indicating that the degree of carbonization increased as the pyrolysis progressed. Visualization of the char's chemical structure revealed that some of the substructures in the initial structure remained intact at low temperatures; however, at high temperatures, unsaturated carbon chains were formed owing to dehydrogenation and deoxygenation, resulting in the formation of char with a polycyclic structure. ReaxFF MD simulations can contribute to the understanding of the mechanism of char formation as well as the yield of reaction products as pyrolysis characteristics of lignin.

Return to Publications page