One-pot Synthesis of Fe Modified Lignin Biochar for Ex-Situ Catalytic Fast Pyrolysis of Enzymatic Hydrolysis Lignin to Promote the Generation of Aromatic Hydrocarbons

The utilization of waste lignin to produce bio-oil rich in aromatics aromatic hydrocarbons is promising and attractive for a wide range of applications. Fe-modified lignin biochar (xFe/ALC) prepared using a one-step method was utilized as catalysts to investigate their impact on product distribution, aromatic hydrocarbon generation, and pathways during ex-situ catalytic fast pyrolysis of enzymatic hydrolysis lignin. The results revealed that the addition of Fe enhanced the production of gas products such as H2, while decreasing bio-oil yield. The lowest bio-oil yield, at 12.10 wt%, was observed at a Fe loading of 25 wt%, however the relative content of aromatic hydrocarbons reached a maximum value of 16.24 area%. Compared to the pyrolysis of lignin alone, their contents increased by 2.46 times, with the content of monocyclic aromatic hydrocarbons (toluene, ethylbenzene, styrene, xylene) increasing by 1.5-3.8 times. Spent 25Fe/ALC had good stability on the production of aromatic hydrocarbons. Compared with non-catalytic pyrolysis of lignin, the aromatic hydrocarbons content for spent 25Fe/ALC after four cycles increased by 26.70%.