Table 1.
Structures, isolations, and/or treatments of Kraft lignin, organosolv lignin, and alkali lignin, and their pyrolytic behaviors
| Raw material | Isolation | Treatment | Lignin | Lignin properties | Pyrolysis temperature | Pyrolytic property | Refs. | |
|---|---|---|---|---|---|---|---|---|
| Yield | Major compositions in oils | |||||||
| Commercial Kraft lignin (KL) | N/A | N/A | KL | G/S-type lignin with C = 62.45%, H = 5.28%, N = 0.27%, O = 31.01%, S = 0.16%, ash = 0.83, H/Ceff = 0.63 | RT-400–700 °Ca | 400 °Ca—gas/oil/char (10/21/69%); 500 °Ca—gas/oil/char (19/33/48%); 600 °Ca—gas/oil/char (24/34/43%); 700 °Ca—gas/oil/char (33/29/38%) | 400–700 °Cb (S-type phenols from 58 to 72%, G-type phenols from 18 to 22%) | [188] |
| Norway spruce (Picea abies) | LignoBoost process | N/A | KL (Lignoboost™ lignin) | G-type lignin with HHV (dry ash free) = 27.1 MJ/kg, HHV (moist) = 18.2 MJ/kg, C = 65.1%, H = 5.8%, N = 0.1%, O = 26.1%, S = 2.5% | RT-500 °Cc | 500 °Cc—char (36%) | 500 °Cc (guaiacols, catechols, alkylphenols) | [116] |
| Black liquor of eucalypt Kraft pulping | Acid precipitation | Thermal treatment (175, 200, 225 °C for 30, 90, 150 s) | Thermal-treated KL | KL-200 °C (90 s) (exp.): G/H/S-type lignin with C = 66.30%, H = 5.63%, N = 0.11%, O = 26.07%, S = 1.70%, HHV = 26.52 MJ/kg, soluble lignin = 5.97%, insoluble lignin = 91.41%, sugars = 0.80%, ash = 1.56% | RT-550 °Cc | 550 °Cd—char (~ 10%) | 225 °Cc (methoxycatechol syringol, 4-methylsyringol) | [189] |
| Black liquor of poplar Kraft pulping | Acid precipitation | Fractionation by ultrafiltration | KL and F1 (54.3%), F2 (25.9%), F3 (15.4%), F4 (4.4%) fractionated in series by membranes with 10, 5, 1 kDa | KL/F1/F2/F3/F4: G/H/S-type lignin with Mn = 584/1141/703/484 g/mol, Mw = 1507/2640/1119/700 g/mol, Ðe = 2.58/2.31/1.59/1.44, acid-insoluble lignin (AIL) = 76.68/78.41/77.62/75.35/76.56%, acid soluble lignin (ASL) = 5.19/5.31/7.09/7.13/6.97%, total carbohydrates = 4.99/8.11/3.69/0.07/0%, ash = 0.95/1.84/1.19/1.07/1.09% | RT-500, 650, 800 °Cc | 750 °Cd—char: KL (35.1%), F1 (33.8%), F2 (25.3%), F3 (31.8%) | 500 °Cc: KL, F1, F2, F3 (syringol, 4-methylguaiacol, guaiacol); 650 °Cc: KL (syringol, 4-methylguaiacol, guaiacol), F1 (4-methylguaiacol, guaiacol, 4-vinylguaiacol), F2 (syringol, guaiacol, phenol), F3 (syringol, guaiacol, 4-vinylguaiacol); 800 °Cc: KL (phenol, syringol, toluene), F1 (phenol, 4-methylphenol, 2,4-dimethylphenol), F2 (syringol, guaiacol, 4-vinylguaiacol), F3 (phenol, syringol, 4-vinylguaiacol) | [154] |
| Black liquor of eucalypt Kraft pulping | Acid precipitation | Fractionation by organic solvents | KL and F1 (59.65%), F2 (28.70%), F3 (10.93%) fractionated in series using ethyl acetate (F1), acetate/petroleum ether (F2), petroleum ether (F3) | KL/F1/F2/F3: G/S-type lignin with Mn = 2033/2872/1611/620 g/mol, Mw = 4664/6158/2397/814 g/mol, Ðe = 2.29/2.14/1.49/1.32, C = 61.30/61.01/62.26/62.49%, H = 5.56/5.59/5.80/5.92%; N = 0.19/0.28/0.01/0.00%, O = 30.81/30.86/29.92/29.91%, S = 2.14/2.26/2.01/1.68%, O/C (mol/mol) = 0.38/0.38/0.36/0.36, H/C (mol/mol) = 1.09/1.10/1.12/1.14, HHV = 24.86/24.80/25.55/25.73 kJ/kg, S/G (unit ratio) = 2.44/2.12/2.32/2.49, β-O-4 = 3.7/12.6/2.8/0%, β–β = 1.2/2.2/0.9/0.3%, β-5 = 5.4/5.5/4.8/4.2%, aliphatic OH = 1.06/1.47/0.84/0.29 mmol/g, total phenolic OH = 3.81/2.51/3.49/4.81 mmol/g, COOH = 0.54/0.49/0.52/0.73 mmol/g, condensed phenolic OH = 0.48/0.35/0.54/0.81 mmol/g, methoxy = 6.86/6.11/6.59/7.19 mmol/g | RT-400, 500, 600 °Cf | 600 °Cd—char: KL (40.61%), F1 (38.88%), F2 (33.32%), F3 (18.37%) | 400 °Cb, g: KL, F1, F2, F3 (G-/S-type phenols); 500 °Cb, g: KL, F1, F2, F3 (G-/S-type phenols); 600 °Cb, g: KL, F1, F2, F3 (G-/S-/H-type phenols) | [135] |
| Black liquor of poplar Kraft pulping | Acid precipitation | Fractionation by gradient acid precipitation | KL (extracted under pH = 2) and LpH6 (52.5%), LpH4 (29.7%), LpH2 (17.8%) fractionated in series under pH = 6, 4, 2 | KL: G/S/H-type lignin with Mn = 821/1057/703/462 g/mol, Mw = 2118/2399/1057/712 g/mol, Ðe = 2.58/2.27/1.73/1.54, C = 52.89/60.31/60.27/48.42%, H = 4.85/5.28/5.28/3.86%, N = 0.15/0.16/0.30/0.22%, O = 29.51/32.57/32.13/23.61%, S = 12.60/1.76/2.02/23.89% | RT-500, 650, 800 °Cc | 750 °Cd—char: KL (35.1%), LpH6 (38.4%), LpH4 (29.1%), LpH2 (26.8%) | 500 °Cc: KL, LpH6, LpH4 (syringol, 4-methylguaiacol, guaiacol), LpH2: (syringol, 4-ethylguaiacol, guaiacol); 650 °Cc: KL (syringol, 4-methylguaiacol, guaiacol), LpH6, LpH2 (syringol, 4-ethylguaiacol, guaiacol), LpH4 (3-methoxycatechol, syringol, 4-methylguaiacol); 800 °Cc: KL (phenol, syringol, toluene), LpH6 (acetosyringone, 3-methoxycatechol, phenol), LpH4 (syringol, 4-ethylguaiacol, 4-methylguaiacol), LpH2 (syringol, phenol, guaiacol) | [190] |
| Commercial alkali lignin (AL) | N/A | N/A | AL | G/H/S-type lignin with C = 55.3%, H = 5.3%, N = 0.1%, O = 35.2%, S = 1.3%, HHV = 20.62 MJ/kg, volatiles = 62.3%, fixed carbon = 34.9%, ash = 2.8% | RT-400, 450, 500 550, 600, 650, 700, 750, 800 °Ca | 600 °C–chard (39.0%); 800 °C—chard (40.8%); 400–800 °Ca—gas/oil/char (15/25/65%) | 400–800 °Cb (phenol, 2-methylphenol, 4-methylphenol, 4-ethylphenol) | [221] |
| Commercial alkali lignin | N/A | N/A | AL | G/H/S-type lignin with C = 60.00%, H = 7.18%, N = 0.00%, O = 29.90%, S = 2.92%, HHV = 20.62 MJ/kg, moisture = 6.2%, volatiles = 88.0%, fixed carbon = 9.4%, ash = 2.6% | RT-300, 350, 400, 450 °Ca | 300 °Ca—gas/oil/solid (11.8/26.2/62.0%); 350 °Ca—gas/oil/solid (12.7/32.3/55.0%); 400 °Ca—gas/oil/solid (16.5/33.5/50.0%); 450 °Ca—gas/oil/solid (20.9/34.1/45.0%) | 300, 350, 400, 450 °Cb (guaiacols, alkyl phenols, catechols) | [204] |
| Commercial alkali lignin | N/A | N/A | AL | G/H/S-type lignin | 40–900 °Cc, i | 900 °Cd—char (~ 50%) | 300, 500, 900 °Cc (2-methoxy-phenol) | [222] |
| Commercial alkali lignin | N/A | N/A | AL | G/H-type lignin with aliphatic OH/COOH/phenolic OH/total OH/H (unit)/G (unit) = 2.36/0.38/3.35/6.09/0.27/3.08 mmol/g | RT-400, 500, 600 °Cc | N/A | 400 °Cb (no obvious response); 500, 600 °Cb (2-methoxyl-4-methylphenol, acetaldehyde, 2-methoxyl-4-vinylphenol, 2-methoxyl-phenol) | [39] |
| Black liquor (BL) | Acid precipitation | Fractionation by ultrafiltration | AL, AL-10/5/1 kDa | AL, AL-10/5/1 kDa: G/H-type lignin with Mn = 3284/6076/4045/2616 g/mol, Mw = 7423/12,060/6752/3864 g/mol, Ðe = 2.260/1.985/1.669/1.478, G-type OH = 0.90/1.07/0.86/0.77 mmol/g, H-type OH = 0.22/0.15/0.17/0.30 mmol/g, aliphatic OH = 1.23/1.47/1.06/1.05 mmol/g, condensed phenolic OH = 1.21/1.74/1.17/1.00 mmol/g, COOH = 1.02/1.19/0.74/0.76 mmol/g | RT-400, 600, 800 °Ch | 1000 °Cd—char: AL (43.06%), AL-10 kDa (38.42%), AL-5 kDa (39.27%), AL-1 kDa (36.34%) | 400 °Cb: AL, AL-10 kDa (guaiacol, 4-methylguaiacol, 4-ethylguaiacol), AL-5 kDa, AL-1 kDa (guaiacol, phenol, 4-methylguaiacol); 600 °Cb: AL, AL-10 kDa, AL-5 kDa (guaiacol, phenol, 4-methylguaiacol), AL-1 kDa (phenol, 4-methylphenol, 3-ethylphenol); 800 °Cb: AL, AL-10 kDa, AL-5 kDa (phenol, indene, naphthalene), AL-1 kDa (1-ethenyl-2-methyl-benzene, indene, naphthalene), (39.27%) | [205] |
| Corncob residue | Organosolv method (tetrahydrofuran) | N/A | Organosolv lignin (OL) | G/S/H-type lignin with Mn = 1238 g/mol, Mw = 3203 g/mol, Ðe = 2.59 | RT-800 °Ca | 350 °Ca—gas/oil/char (31.5/16.3/52.2%); 800 °C—chard (36.02%) | 350 °Cb (4-vinylphenol, 4-vinylguaiacol, syringol) | [223] |
| Pine, poplar, bamboo | Organosolv method (dioxane) | N/A | PiL (29.3%), PoL (35.2%), BaL (48.9%) | PiL: G/H-type lignin with Mn = 2580 g/mol, Mw = 9940 g/mol, Ðe = 3.85, β-O-4 (A) = 46.02%, phenylcoumarans (B) = 8.63%, resinol (C) = 5.78%, cinnamyl alcohol end groups (I) = 6.72%, S/G/H (unit) = 0/99.35/0.65%; PoL/BaL: G/S/H-type lignin with Mn = 3540/3420 g/mol, Mw = 13,240/8840 g/mol, Ðe = 3.74/2.58, β-O-4 (A) = 56.31/59.52%, phenylcoumarans (B) = 7.13/5.68%, resinol (C) = 13.56/4.16%, cinnamyl alcohol end groups (I) = 0/0%, S/G/H (unit) = 69.00/30.62/0.38% (60.97/35.79/3.24%) | RT-800 °Ca | 800 °Cd—char: PiL (39.33%), PoL (30.19%), BaL (20.71%) | 400–600 °Cb: PiL (guaiacol), PoL (phenol), BaL (4-vinylphenol) | [110] |
| Sugarcane bagasse (BG) | Organosolv method (ethanol) | N/A | BG-Lignin | G/S/H-type lignin with G/S/H (unit ratio) = 0.82/0.02/0.16; moisture = 3.78%, volatiles = 67.34%, fixed carbon = 28.80%, ash = 0.09%, phenolic OH/aliphatic OH = 0.79 | RT-400, 500, 600, 700 °Cc | 800 °Cd—char (29%) | 400 °Cc (2,6-dimethoxy-phenol); 500 °C–600 °Cc (2,6-dimethoxy-4-(2-propenyl)-phenol); 700 °Cc (4-ethyl-phenol) | [216] |
| Willow biomass | Organosolv method (ethyl acetate-EAC/tetrahydrofuran-THF/γ-butyrolactone-GBL) | N/A | L-EAC (83.8%), THF (92.3%), GBL (72.6%) | L-EAC/L-THF/L-GBL: G-type lignin with C = 65.00/66.25/66.88%, H = 6.26/6.03/6.32%, N = 0.22/0.30/0.21%, O = 28.09/27.00/26.61%, ash = 0.44/0.12/0%, moisture = 4.5/4.0/4.5% | RT-500 °Ca | 500 °Ca—gas/oil/char: L-EAC (22.15/34.53/43.32%), L-THF (20.97/35.21/43.83%), L-GBL (21.70/33.55/44.75%) | 500 °Cb: L-EAC, L-THF (guaiacol, 4-methylguaiacol), L-GBL (4-methylguaiacol) | [220] |
aA fixed bed
bGC/MS and/or GC/FID (gas chromatograph/flame ionization detection)
cPy-GC/MS
dTG-DTG
eDispersity
fU-type tube pyrolysis device
gIn situ FTIR spectroscopy
hTube furnace
iTG–MS (thermogravimetry–mass spectrometry)