A comprehensive understanding of the synergistic effect during co-pyrolysis of polyvinyl chloride (PVC) and coal

In this work, the co-pyrolysis behaviors of polyvinyl chloride (PVC) with coal were investigated using the reactive molecular dynamics (ReaxFF MD) simulations. The weight loss characteristics of PVC and coal pyrolysis obtained from ReaxFF MD simulations were in good agreement with the thermo-gravimetric (TG) experimental results. The synergistic effect on the production of inorganic gas, organic gas, and tar were investigated via co-pyrolysis simulations. The results showed that coal promoted HCl release by providing extra H for Cl radicals. It led to more H being retained in the de-HCl PVC, resulting in an increase of C2H4 yield and a decrease of C2H2 yield. PVC promoted the generation of CO2, CO and CH2O, while inhibited the generation of H2O. PVC had little effect on coal pyrolysis tar yield because little H radicals were generated from PVC pyrolysis. However, large amount of H and OH radicals were generated from coal pyrolysis, leading to a promoting effect on the decomposition of PVC and the secondary reactions of PVC pyrolysis tars. Kinetic results suggested that the synergistic effect reduced the activation energy by 13% at low temperature stage, while reduced the activation energy by 36% at high temperature stage during PVC/coal co-pyrolysis.