Research on the microscopic reaction mechanism of cellulose pyrolysis using the molecular dynamics simulation

•A large-scale cellulose model containing 21,020 atoms is constructed and validated.•Reactive molecular dynamics simulations of cellulose pyrolysis are conducted.•The distribution and temporal evolution behavior of pyrolysis products are studied.•The major generation and consumption pathways for main products are tabulated.•The cleavage behaviors of different types of bonds are presented and analyzed. Pyrolysis is one of the main techniques used for the transformation and utilization of biomass, and elucidating the microscopic pyrolysis mechanism can help improve the process efficiency. In this study, a large-scale cellulose model containing 21,020 atoms is constructed. Furthermore, reactive force field molecular dynamics simulations are conducted to explore its atomistic transformation mechanism. The distributions of pyrolysis products containing different numbers of carbon atoms over a wide temperature range (1000−3000 K) are first analyzed. The temporal evolution behaviors of the main product species (e.g., H2, CO, CH4, CO2, CH2O, H2O and H radicals) are also explored. In addition, the major generation and consumption pathways for each main product species are tabulated and discussed based on analyses of the chemical reactions and the corresponding frequencies. Finally, the cleavage behaviors of different types of bonds during the initial stage of cellulose pyrolysis are presented. These results and observations can contribute toward a more extensive understanding of the pyrolysis mechanism of the cellulose in biomass.