Mechanistic Study on the Enhanced Synergistic Effect in Co-pyrolysis of Huangling Coal and Enzymatic Hydrolysis Lignin via Hydrothermal Pretreatment

• • Hydrothermal pretreatment (24 h) of Huangling coal and enzymatic hydrolysis lignin reduces O/C ratio and increases fixed carbon, while developing pore structures and surface cracks, as confirmed by SEM and ultimate analysis. • • Co-pyrolysis of H/E blend (8:2) after 24 h HTP achieves an 80.52% increase in tar yield, with significant enrichment of aliphatic compounds and monocyclic aromatic hydrocarbons, indicating enhanced oil quality. • • Gas yields of H2, CO, and CH4 increase by 5.47%, 10.98%, and 9.27%, respectively, while CO2 generation is inhibited; pyrolysis water yield drops by 93.98%, improving gas calorific value and process efficiency. • • The synergistic mechanism involves 'component interaction-structural modification-catalytic cracking', where inorganic ions (Ca, K, Fe) leached during HTP act as catalysts, and structural convergence of H and E promotes thermal compatibility, leading to superior co-pyrolysis performance.