Enhancing bio-aromatics yield in bio-oil from catalytic fast pyrolysis of bamboo residues over bi-metallic catalyst and reaction mechanism based on quantum computing

Abstract

The high oxygen content and complicated compounds of pyrolysis bio-oil limit its application as a liquid fuel. In this study, bi-metallic modified HZSM-5 was used to enhance bio-aromatics yield in bio-oil from catalytic pyrolysis of bamboo residues. The catalytic pyrolysis behavior of bamboo residues over Fe and Zn co-modified HZSM-5 with different Fe to Zn mass ratios, loading rates, and different catalyst to biomass mass ratios towards the selectivity of aromatics was investigated using pyrolysis–gas chromatography/mass spectroscopy (Py-GC/MS). Quantum calculation of oxygen-containing products was used to infer the reaction mechanism. The results showed that Fe and Zn could adjust the strong acidity and pore size distribution of HZSM-5. The bi-metallic modified HZSM-5 promoted deoxygenation activity and monocyclic aromatic hydrocarbons yield. Zn modified HZSM-5 catalyst yielded higher aromatics than Fe modified HZSM-5. Maximum aromatics yield of 93.83 mg g−1 was obtained when the Fe to Zn mass ratio was 4:1 at a loading rate of 5 wt%(Fe and Zn). However when catalyst to biomass mass ratio exceeded 2:1, the yield of aromatics decreased. Quantum calculations showed that 2-Methoxy-4-vinylphenol had the largest dipole moment and the smallest energy band gap among the selected aromatic oxygen-containing compounds, indicating its weak molecular stability. Theoretical support for the hypothesis of the 2-Methoxy-4-vinylphenol pyrolysis pathway was provided by the analysis of the bond dissociation energy.