Lignin Fractionation in Segmented Continuous Flow

Lignins were fractionated in a segmented continuous flow fractionation (SCFF) approach using isocratic or gradient elution profiles of different solvent systems at various flow rates and temperatures against adjustable pressure regimes. Superior control of parameters such as temperature and pressure in combination with the possibility of freely combinable solvent gradients allowed facile fractionation and generation of industrially interesting fractions differing in molecular weight properties and/or in physicochemical properties in a process that could be fully remotely controlled for automation and performance. Scale-up of the process was possible in linear and parallel mode. Analyses of the realised fractions by standardised gel permeation chromatography and 31P NMR spectroscopy protocols showed that the SCFF of lignins delivered fractions that could be similar to conventional batch fractions, as well as novel/altered fractions available by applying overheated solvents in pressurised systems.