Towards optimal selective fractionation for Nordic woody biomass using novel amine–organic superbase derived switchable ionic liquids (SILs)

• Abstract Improved fractionation process conditions for wood dissolution with switchable ionic liquids (SILs) were determined. The short time, high temperature (STHT) system was introduced as a selective and efficient way to extract components from lignocellulosic material. A SIL based on monoethanol amine (MEA) and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) formed via coupling with SO2, was applied as a solvent in a 1:3 weight ratio with water. In essence, selective dissolution of mainly lignin was achieved by means of the aqueous SIL at 160 °C (∼6.1 bar corresponding to the vapor pressure of water) in 2 h and in a pressure vessel, for both hard- and soft-wood. About 95 wt-% of wood lignin was extracted. The dissolved components in the spent SIL were recovered by the addition of an anti-solvent whereupon over 70% of the dissolved components were recovered; the recovered fraction contained 19 wt-% hemicellulose while the rest of the material was in essence lignin. The non-dissolved, fluffy material contained ∼70 wt-% cellulose and ∼20 wt-% hemicellulose – a consistency resembling that of Kraft pulp.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Switchable ionic liquids

Optimal selective fractionation of lignin

Hardwood

Softwood

Gel permeation chromatography (GPC)

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