title: Production of polyols via direct hydrolysis of kraft lignin: effect of process parameters.
abstract: Kraft lignin (KL) was successfully depolymerized into polyols of moderately high hydroxyl number and yield with moderately low weight-average molecular weight (Mw) via direct hydrolysis using NaOH as a catalyst, without any organic solvent/capping agent. The effects of process parameters including reaction temperature, reaction time, NaOH/lignin ratio (w/w) and substrate concentration were investigated and the polyols/depolymerized lignins (DLs) obtained were characterized with GPC-UV, FTIR-ATR, (1)H NMR, Elemental & TOC analyzer. The best operating conditions appeared to be at 250°C, 1h, and NaOH/lignin ratio ≈0.28 with 20 wt.% substrate concentration, leading to <0.5% solid residues and ∼92% yield of DL (aliphatic-hydroxyl number ≈352 mg KOH/mg and Mw≈3310 g/mole), suitable for replacement of polyols in polyurethane foam synthesis. The overall % carbon recovery under the above best conditions was ∼90%. A higher temperature favored reduced Mw of the polyols while a longer reaction time promoted dehydration/condensation reactions.
authors: Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, ON, Canada N6A 5B9.
authors: Nubla
authors: N
authors: Mahmood
authors: Zhongshun
authors: Z
authors: Yuan
authors: John
authors: J
authors: Schmidt
authors: Chunbao
authors: C
authors: Charles Xu
mesh_terms: D001709:Biotechnology / Q000379:methods*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D006868:Hydrolysis / Q000187:drug effects; D008031:Lignin / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D058105:Polymerization / Q000187:drug effects; D011108:Polymers / Q000138:chemical synthesis*; D012972:Sodium Hydroxide / Q000494:pharmacology; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013997:Time Factors
chemical_list: D011108:Polymers; C024617:polyol; D012972:Sodium Hydroxide; C076151:Kraft lignin; D008031:Lignin