Effects of Interactions among Cellulose, Hemicellulose, and Lignin on the Formation of Heavy Components in Bio-oil during Oxidative Pyrolysis

Oxidative pyrolysis eliminates the need for external heating in large-scale industrial applications by autothermal reactions. Heavy components in bio-oil (molecular weight >200 Da) tend to generate coke when heated, causing reactor blockages and catalyst deactivation. This research aimed to elucidate the effects of interactions among the three components of biomass on the generation of heavy components. Both oxidative pyrolysis with an oxygen concentration of 4 vol % and conventional experiments were conducted at 500 °C. The results showed that the interactions among the three components presented different effects on the formation of heavy components. The interactions between cellulose and hemicellulose promoted the formation of heavy components by enhancing the homogeneous oxidation of volatiles, e.g., increasing the content of heavy components (200–300 Da) by 103%. Similarly, the interactions between hemicellulose and lignin promoted the polymerization of volatiles during oxidative pyrolysis to generate heavy components, e.g., increasing the content of heavy components (O ≥ 4) by 71%. However, the interactions between cellulose and lignin promoted the decomposition of heavy components (≥300 Da, O ≥ 5) to generate those (<300 Da, O < 5).