Table 5.
Summary of catalytic depolymerization of technical lignin without external hydrogen.
|
Biomass feedstock |
Lignin type |
Solvent |
Catalyst/ additive |
T [°C] |
t [h] |
Gas/pressure |
Monomer yield [wt %] |
Major products[a] |
Ref. |
|---|---|---|---|---|---|---|---|---|---|
|
candlenut |
organosolv lignin |
MeOH |
Cu20La20PMO |
310 |
1 |
– |
34 |
4‐propyl‐2,3,5 methyl‐phenol |
[92] |
|
hardwood |
Kraft lignin |
H2O/MeOH (3 : 1 v/v) |
CuMo/ZSM‐5 |
220 |
7 |
Ar |
20.6 |
phenol, 3‐methoxy, 2,5,6‐trimethyl (PMT) |
[93] |
|
bamboo |
cellulolytic enzyme lignin |
MeOH/H2O (5 : 2 v/v) |
Raney Ni+H‐USY |
270 |
0.5 |
1 atm N2 |
27.9 |
EG, PG |
[94] |
|
hardwood |
Kraft lignin |
MeOH |
HZSM‐5 |
220 |
7 |
Ar |
4.2 |
G, S |
[95] |
|
wheat straw |
alkali lignin |
EtOH |
CuMgAlOx |
300 |
8 |
10 bar N2 |
23 |
G, MG |
[96] |
|
switchgrass |
ionic liquid lignin |
iPrOH |
5 % Ru/C |
300 |
3 |
20 bar N2 |
27 |
PenG, PenS, EG |
[97] |
|
sorghum |
DES extracted lignin |
iPrOH |
5 wt % Ru/C |
270 |
1 |
N2 |
27.39 |
P, EP, EG, PG |
[47a] |
|
– |
Kraft lignin |
iPrOH/H2O |
Rh/La2O3/CeO2−ZrO2+Fe |
373 |
2 |
– |
26.4 |
– |
[98] |
|
– |
lignosulfonate |
H2O/n‐BuOH/iPrOH (1 : 1 : 3) |
Raney Ni |
200 |
2 |
1.0 MPa N2 |
11.6 |
EG |
[99] |
|
corn stalk |
cellulolytic enzyme lignin |
iPrOH/H2O (2 : 1 v/v) |
Ni50Pd50/ SBA‐15 |
220 |
8 |
0.5 MPa N2 |
8.14 |
EP, ES, PS |
[100] |
|
birch |
acid‐extracted lignin |
|
|
245 |
8 |
|
18.52 |
PS |
|
|
beech |
organosolv lignin |
iPrOH |
Ni/Al2O3 |
170 |
12 |
10 bar N2 |
13.4 |
PenS, sinapyl alcohol, coniferyl alcohol |
[89] |
[a] P: phenol; EP: 4‐ethyl phenol; G: guaiacol; MG: 4‐methyl guaiacol; EG: 4‐ethyl guaiacol; PG: 4‐propyl guaiacol; PenG: 4‐propenyl guaiacol; S: syringol; ES: 4‐ethyl syringol; PS: 4‐propyl syringol; PenS: 4‐propenyl syringol.