Table 1 Aromatic compounds generated from the depolymerization of lignin

Catalytic

Cu-CrO

Hardwood lignin

Methanol, 4-n-propylcyclohexanol, 4-n-propylcyclohexanediol, and glycol

[49]

Mo

Kraft pine lignin

Phenol, cyclohexane, benzene, naphthalene, and phenanthrene

[50]

H₃PMo₁₂O₄₀

Kraft lignin

Vanillin and methyl vanillate

[51]

CuSO₄/FeCl₃

Yellow poplar wood chips

Vanillin, syringaldehyde, acetovanillone, and acetosyringone

[52]

CuO

Hardwood kraft lignin

Syringaldehyde, vanillin, syringic acid, and vanillic acid

[53]

Ionic liquid

[C2mim][OAc] at 160 °C

Kraft lignin, eucalyptus, switchgrass, pine

Guaiacol, vanillin, syringol, eugenol, and catechol

[5]

Microbial

Aneurinibacillus aneurinilyticus

Kraft lignin

Guaiacol, acetoguiacone, gallic acid, and ferulic acid

[54]

Bacillus sp.

Kraft lignin

Ferulic acid, 3,4,5 trimethoxy benzaldehyde, and t-cinnamic acid

[55]

Rhodococcus jostii RHA1 mutant

Wheat straw lignocellulose

Vanillin, 4-hydroxybenzaldehyde, and ferulic acid

[8]

Novosphingobium sp. B-7

Kraft lignin

Ethanediol, p-hydroxybenzoic acid, and vanillic acid

[56]

Enzymatic

A β-O-4 linkage cleaving enzyme system (LigDFG)

Softwood alkali-lignin and hardwood alkali-lignin

Guaiacol, ferulic acid, eugenol, vanillin, and acetovanillone

[57]