Pd-catalyst assisted organosolv pretreatment to isolate ethanol organosolv lignin retaining compatible characteristics for producing phenolic monomer

The aims of this study were to produce both sugar and ethanol organosolv lignin (EOL) by acid-catalyzed organosolv pretreatment of yellow poplar and to investigate the effect of introduction of palladium on productivity and characteristics of produced EOL. Regardless of palladium introduction, sugar production was remained stable at 145 °C, but it was slightly increased at 160 °C due to higher lignin removal. Addition of palladium also significantly enhanced the EOL yield especially at 160 °C (from 13.4 g to 16.3 g). Furthermore, it prevents cleavage of ether linkages and condensation reaction of lignin while Mw is decreasing, and consequently ether linkage rich EOL released larger amount of phenolic monomers compounds. Released amount of total phenolic monomers was significantly decreased with pretreatment temperature increased (145 °C: 1.4 g; 160 °C: 0.5 g), however it was remarkably enhanced when palladium was introduced (from 0.5 g to 2.0 g).