• • Ca2+ at 7% mass ratio increased biochar yield to 24.96% and H2 volume fraction to 32.49%, demonstrating its strong Lewis acidity for gas-phase enhancement and carbon retention.
• • Ca2+ catalysis enriched furan compounds to 65.88% (and 65.89% at 600 °C), indicating high selectivity for deoxygenation and valuable chemical production.
• • K+ at 600 °C promoted acid formation to 39.41%, while low K+ concentrations favored phenolics, showing concentration-dependent catalytic pathways for bio-oil composition control.
• • Raising pyrolysis temperature from 400 to 600 °C decreased biochar yield and increased gas yield, with H2 and CH4 yields significantly enhanced, enabling process optimization for syngas production.