Insight into the synergistic performance during ex-situ catalytic co-pyrolysis of poplar sawdust and polypropylene over Fe-Ni/ZSM-5 for the enhancement of aromatics

Abstract

Hydrogen-deficient and oxygen-rich biomass result in low hydrocarbon production during pyrolysis. This work aims to enhance aromatics in bio-oil through ex-situ catalytic co-pyrolysis of poplar sawdust (PS) and polypropylene (PP) over Fe-Ni/ZSM-5 and gain an understanding of the synergistic pyrolysis performance. The results showed that adding PP improved the comprehensive pyrolysis performance of the PS and PP blends. The deviation between the experimental and calculated mass loss of the blends confirmed the interaction between PS and PP, with a more positive synergistic effect at a biomass/plastic mass ratio of 3:2. The average activation energy of PP was 211.6 kJ·mol−1, which is 28.2 % higher than that of PS. As the proportion of PP increases, the activation energy required for the blends increases. The established artificial neural network model accurately predicts the mass loss of the blends (R2 ≥ 0.999) by providing the mixing ratio, heating rate, and temperature. The addition of hydrogen-rich feedstock increased aromatic yield in the volatile products, indicating the positive synergy between PS and PP during catalytic co-pyrolysis over Fe-Ni/ZSM-5. As the targeted products among the aromatics, the total yields of benzene, toluene, and xylene ranged from 58.43 to 251.03 mg·g−1 in the PS and PP blends, respectively.