Valorizing Kraft Lignin by a Catalytic Reductive Depolymerization in Ethanol/Water with Formic Acid as a Supplementary H2 Donor

Lignin is a promising biopolymer to serve as sustainable resource for multitude of applications (e.g., thermoset materials, production bulk chemicals) thereby substituting fossil-based carbon sources. In this work, the reductive depolymerization Kraft lignin (KL) was studied in ethanol/water aided by formic acid (FA) way forward valorize lignin. The effect various process conditions elucidated using 31P-NMR, pH, GPC, CHNSO, GC–MS and 2D-LC analyses. It found that addition small amount FA (3.6 vol%) beneficial obtaining smaller fragments with more phenolic OH (PhOH) functionalities upon at 250 °C 8 h. Besides, higher concentration causes catalyzed repolymerization longer reaction time results only limited reduction molecular weight obtained fragments. supported Pd catalyst leads pronounced (smaller PhOH functionalities) well stronger decrease oxygen sulfur content. Furthermore, several experiments multiple analysis techniques support hypothesis acts H2 donor under investigated study. conclusion, KL (MW ~ 16,436 g mol?1 3.31 mmol g?1 PhOH) successfully depolymerized into low 3250 mol?1) (5.29 g?1).