Components interaction and its impacts on aromatic structures and coking behavior during catalytic and non-catalytic pyrolysis of bio-oil

Bio-oil holds great promise as a renewable alternative to fossil fuels via upgrading. Its catalytic pyrolysis upgrading is often limited by severe coking, which hinders further technological advancement. Component interaction plays an important role in coke formation during bio-oil pyrolysis. However, the influence remains unclear when the catalyst is introduced. Therefore, this study aims to elucidate the interactions among components during catalytic bio-oil pyrolysis and to investigate their effects on aromatic evolution and coking behavior. Results indicate that increasing temperature from 600 °C to 800 °C inhibits coke formation during bio-oil pyrolysis, decreasing coke yield (based on heavy components basis) from 31.2 % to 20.1 %. Interactions among bio-oil components can facilitate the cracking of heavy tar into small-molecule aromatics, thereby suppressing the formation of large aromatic systems, decreasing coke yields (based on heavy components) from 27.5 % to 23.1 % at 600 °C. In contrast, the introduction of a catalyst promotes the transformation of monocyclic aromatics into bicyclic ones, but inhibits their further condensation into coke, further decreasing coke yields (based on heavy components) from 18.5 % to 16.8 % at 800 °C. This work provides valuable insights into understanding the coking mechanism during catalytic pyrolysis of bio-oil and offers guidance for catalyst design.