Enhancement of aromatic monomer production from pyrolysis of lignin-related β-O-4 contained model compound

- Aromatic monomers produced from PPE pyrolysis was notably promoted by methanol addition.
- The hydrogen on phenolics can be specifically substituted by the hydrogen from hydroxyl group of methanol.
- Hydrogen in toluene and ethylbenzene was almost not originated from the hydroxyl group of methanol.

Pyrolysis of lignin-related β-O-4 contained model compound, phenethyl phenyl ether (PPE, C6H5C2H4OC6H5), and co-pyrolysis of PPE with methanol was conducted in a fixed-bed reactor. The aromatic compounds in liquid product from the pyrolysis process were analyzed by GC/FID and GC/MS. The yield of the monomeric aromatic compounds was dramatically increased with the addition of methanol to PPE during the co-pyrolysis process. Formation pathway of styrene and phenol was related to the radical chain reaction, where the concerted retro-ene mechanism was not involved during the co-pyrolysis process. An isotopic tracing method (CH3OD as the tracer) was employed for understanding the role of methanol on the formation pathway of the typical aromatic compounds. The hydrogen on hydroxyl group and o-position in phenolic products was favorably substituted by the hydrogen evolved from hydroxyl group of methanol during co-pyrolysis process. However, hydrogen in toluene and ethylbenzene products can be ignorably originated from the hydrogen released from the hydroxyl group of methanol.