Skip to main content

View full-text article in PMC

. 2022 Oct 11;15:106. doi: 10.1186/s13068-022-02203-0

Table 4.

Structures and isolations/treatments of ionic liquid lignin, and corresponding pyrolytic behaviors

Raw material	Ionic liquid	Isolation/treatments	Lignin	Lignin properties	Pyrolysis temperature	Pyrolytic property		Refs.
Raw material	Ionic liquid	Isolation/treatments	Lignin	Lignin properties	Pyrolysis temperature	Yield	Major compositions in oils	Refs.
Empty fruit bunches (EFB), palm mesocarp fiber (PMF) and palm kernel shells (PKS)	Pyridinium formate [PyFor]	Biomass pretreated by [PyFor], and lignin regenerated via dissolving in acetone/water followed by acetone evaporation	EFB lignin, PMF lignin, PKS lignin	EFB lignin, PMF lignin, PKS lignin: with C = 42.02/42.95/45.59%, H = 6.48/5.70/6.21%, N = 5.74/6.56/7.02%, O = 44.59/44.63/40.90%, S = 0.18/0.16/0.28%, acid insoluble lignin = 17.82/32.23/45.54%, HHV = 27.05/27.40/28.20 MJ/kg	50–550 °C^a	800 °C (10 °C/min)^b—char (exp.): EFB lignin (3.87%), PMF lignin (5.79%), PKS lignin (9.25%)	550 °C^a: EFB lignin (cyclotetradecane, naphthalene, 4-t-butylcyclohexanone), PMF lignin (naphthalene, 4-t-butylcyclohexanone, phenol), PKS lignin (phenol, 2-methoxy-phenol, 2,4-dimethylphenol)	[271, 274]
Sugarcane straw (SCS)	1-Ethyl-3-methylimidazolium acetate [Emin][OAc]	SCS pretreated by [Emin][OAc] at 90 °C for 5 h, and lignin recovered via dissolving in acetone/water followed by acetone evaporation	Recovered lignin	N/A	50–700 °C^c	700 °C—char^d: 44%	350 °C^c: phenols, methanol, formaldehyde	[125]
Industrial lignin	1-Butyl-3-methylimidazolium chloride (BMIC)	Lignin pretreated in a microwave apparatus using BMIC at 50, 100, 150 °C for 30 min and precipitated using water	BMIC-lignin₅₀, BMIC-lignin₁₀₀, BMIC-lignin₁₅₀	N/A	RT-300, 400, 500, 600, 700, 800°C^e	300–400 °C^e-liquid (exp.): BMIC-lignin₅₀ (~ 0.150 g/g_lignin), BMIC-lignin₁₀₀ (~ 0.125 g/g_lignin), BMIC-lignin₁₅₀ (~ 0.125 g/g_lignin)	300–500 °C^f: BMIC-lignin₅₀, BMIC-lignin₁₀₀, BMIC-lignin₁₅₀ (phenolics, arenes, alkanes)	[280]
Industrial lignin	1-Sulfonic acid butyl-3-methylimidazolium trifluoromethanesulfonate [B(SO₃H)min]-OTf	Lignin pretreated in a microwave apparatus using [B(SO₃H)min]-OTf at 50, 100, 150, 200 °C for 1 h under N₂, and regenerated by washing with water	Lignin-50, lignin-100, lignin-150, lignin-200	Industrial lignin: ash = 3.77%, volatiles = 56.73%, C = 66.22%, H = 6.30%, O = 25.58%, N = 1.09%, S = 0.81%	RT-300, 400, 500, 600, 800°C^e	300–400 °C^e—tar (exp.): Lignin-50 (0.1889 g/g_lignin) lignin-100 (0.1231 g/g_lignin) lignin-150 (0.1338 g/g_lignin) lignin-200 (0.0751 g/g_lignin)	300–500 °C^f: Lignin-50, lignin-100, lignin-150, lignin-200 (phenol, guaiacol, 2-ethylphenol, 4-methoxyguaiacol)	[279]
Industrial lignin	1-Butyl-3-methylimidazolium dihydrogen phosphate [Bmin]H₂PO₄	Lignin pretreated in a microwave reactor using [Bmin]H₂PO₄ at 50, 100, 150 °C for 30 min, and washed out by water	Lignin-50, lignin-100, lignin-150	Industrial lignin: moisture = 2.6%, ash = 2.5%, volatiles = 62.4%, C = 63.9%, H = 5.6%, O = 28.6%, N = 1.1%, S = 0.8%	RT-300, 400, 500, 800 °C^e	300–400 °C^e-liquid (exp.): Lignin-50 (~ 0.15 g/g_lignin) lignin-100 (~ 0.12 g/g_lignin) lignin-150 (~ 0.12 g/g_lignin)	300–500 °C^f: lignin-50, lignin-100, lignin-150 (phenolics, arenes, alkanes)	[270]

^aPy-GC/MS

^bTG-DTG

^cTG-FTIR

^dTG-DTG

^eA vertical fixed-bed quartz reactor

^fGC/MS