Catalytic mechanisms of potassium salts on pyrolysis of β-O-4 type lignin model polymer based on DFT study

Abstract In this study, the possible catalytic mechanisms of potassium salts on lignin pyrolysis was investigated with two β-O-4 type lignin model dimers with different oxygen functional groups on Cα using density functional theory (DFT) calculations. It was found that potassium salts (such as KOH and K2CO3) can react with phenol hydroxyl in lignin to form organic-K and further catalyze pyrolysis progress. Through this catalytic mechanism, potassium salts promoted the removal of Cα on specific intermediates and the demethylation of methoxy groups during β-O-4 type lignin pyrolysis, promoted the decomposition of intermediates, and facilitated the formation of phenol and CO2.