Effect of process parameters in pilot scale operation on properties of organosolv lignin

Abstract

One of the major challenges in transforming from fossil to bio-based materials is the production of biomass-derived intermediates in a well-described, reproducible manner at a relevant scale. Lignin, as the only renewable aromatic resource, will play an important role in the future bioeconomy. Various grades of lignin were produced at Fraunhofer CBP’s pilot plant by variations of the following parameters: raw material (beech wood, spruce wood, and wheat straw), H-factor (combining the effect of temperature and time), addition of sulfuric acid ω(H2SO4), and the precipitation procedure. During the optimization of the process conditions for lignin production an in-depth analytical characterization was done by acid hydrolysis with subsequent anion-exchange chromatography (AEC), elementary analysis, 31P-nuclear magnetic resonance spectroscopy (NMR), size-exclusion chromatography (SEC), and differential scanning calorimetry (DSC) to monitor changes in structure and selected properties.