Water content effect on bituminous pyrolysis product distribution with ReaxFF molecular dynamics and experiment

The water atmosphere exerts a profound effect on the coal pyrolysis process. The present study dissects the bituminous pyrolysis product distribution at 0 %-24 % water content and traces the N and S atom migration via the ReaxFF molecular dynamics (MD). The coal mass ratio exhibits a slow-rapid-slow decline as the temperature rises. The coal mass ratio transfers to the pyrolysis heavy tar, light tar, and gas by 2.65 %, 6.46 %, and 16.51 % at 2700 K. The remaining N and S atoms in char are 62.5 % and 43.3 %, and the migrated atoms mainly distribute in the light tar and gas. The N and S atoms tend to remove from the functional group C₄H₅N and R-S-R. The elevated temperature promotes the conversion from C-N and C-S to H-N and H-S that contributes to more NH₃ and H₂S. The minimum char and maximum gas mass arise at the 6 % water content with the lowest total bond number. The heavy and light tar mass peak appears at 12 % and 18 % water content. The active radicals OH∙ and H∙ rise at a higher water content. The research achievement has positive practical significance for the pollution control and efficiency improvement of coal pyrolysis.