Pressure-regulated catalytic co-pyrolysis of medicinal biomass residue and polystyrene for aromatic-rich bio-oil production

Pressurized catalytic co-pyrolysis provides a promising route for converting oxygen-rich medicinal biomass residue (MBR) and polystyrene (PS) into aromatic-rich liquid fuels. In this study, MBR and PS were co-pyrolyzed over Fe–Mo/ZSM-5 in a pressurized fixed-bed reactor, and the effects of feedstock ratio, temperature, and pressure on thermal conversion, product distribution, gas composition, and oil quality were evaluated. MBR:PS mass ratios of 2:1, 1:1, 1:2, and 1:3 were investigated, with the 1:3 blend showing the most favorable overall performance. Isoconversional analysis over α=0.2–0.8 showed that Fe–Mo/ZSM-5 reduced the average apparent activation energy from 190.27 to 163.23 kJ mol⁻¹ using the FWO method and from 178.30 to 155.45 kJ mol-1 using the KAS method. The catalyst also lowered the enthalpy requirement and promoted a more ordered surface-assisted conversion pathway. The maximum liquid yield of 78.2 wt.% was obtained at 600 °C and 2 Mpa. Under optimized conditions, Fe–Mo/ZSM-5 enhanced hydrogen transfer, deoxygenation, cracking, and aromatization, producing an oil lower heating value of 41.37 MJ kg-1 and a maximum BTEX content of 46.3%.