Synergistic effect of corn straw and its tar distillation residue during co-pyrolysis: kinetics, thermodynamics, and reaction pathway

This study investigated the kinetics, thermodynamic characteristics, and reaction pathways during the co-pyrolysis of corn straw (CS) and tar distillation residue (TAR-D). Results showed that incorporating 15% TAR-D reduced the peak temperature of the system from 358.2 to 346.5 °C. The average activation energies of CS, TAR-D, and H-15% calculated by the FWO method were 152.42, 143.77, and 147.01 kJ mol−1, respectively, indicating that TAR-D addition lowered the reaction energy barrier of CS and promoted pyrolysis. The ΔH values of the three samples were 147.66, 142.22, and 138.56 kJ mol−1, confirming endothermic reactions. The ΔS of H-15% was negative (−4.94 J mol−1 K−1), indicating more stable energy release and a more ordered product structure. Co-pyrolysis products showed decreased phenols, alcohols, and ketones, while aromatic hydrocarbons and esters increased significantly. Oxygen-containing radicals from CS cracking underwent hydrogen transfer and coupling with aromatic radicals from TAR-D, facilitating aromatic ring reconstruction, deoxygenation of phenolic hydroxyls, and ester formation. This study elucidates the synergistic conversion of CS and TAR-D during co-pyrolysis, providing a theoretical basis for the efficient thermochemical utilization of all CS components.