Table 1 Pretreatment conditions of different biomass and source of lignin fractions

Acid catalyst

Yes

Yes

Yes

No

Forest biomass

Wheat straw

Spruce

Birch

Spruce

Birch

Spruce

Birch

Pretreatment conditions

195 °C, 15 min

225 °C, 5 min, 0.5% w/w_biomass H₂SO₄

200 °C, 5 min, 0.14% w/w_biomass H₂SO₄

182 °C, 60 min, 60% v/v EtOH, 1% w/w_biomass H₂SO₄

182 °C, 60 min, 60% v/v EtOH, 1% w/w_biomass H₂SO₄

200 °C, 30 min, 52% v/v EtOH

200 °C, 30 min, 60% v/v EtOH

Compositional analysis of solid residues

50.2% w/w cellulose, 3.91% w/w hemicellulose, 25.5% w/w lignin

38.2% w/w cellulose, 0% w/w hemicellulose, 53.1% w/w lignin

57.2% w/w cellulose, 12.1% w/w hemicellulose, 27.1% w/w lignin

69.1% w/w cellulose, 1.15% w/w hemicellulose, 25.03% w/w lignin

60.73% w/w cellulose, 1.08% w/w hemicellulose, 15.69% w/w lignin

66% w/w cellulose, 6% w/w hemicellulose, 14.9% w/w lignin

67.1% w/w cellulose, 21.0% w/w hemicellulose, 7.1% w/w lignin

Lignins from solid residues

HT-A-WS

SE-S

SE-B

OS-A-S

OS-A-B

OS-S

OS-B

Lignins from liquid fraction

OS-A-S-LF

OS-A-B-LF

OS-S-LF

OS-B-LF