ILs have many intriguing properties, such as low vapor pressure, high chemical and thermal stability, wide electrochemical window, non-flammability, wide liquid range and recognition ability of biomaterials. They are applied in a variety of fields, including extraction, organic synthesis, catalysis/biocatalysts, materials science, electrochemistry and separation technology. Furthermore, because ILs have ionic nature, they may interact with charged groups in the enzyme, either in the active site or at its periphery, causing changes in the enzyme’s structure.

ILs are promising solvents, for reaction and separation, offers tremendous possibilities for the development of sustainable industry, advanced materials and chemicals. Up to date, cellulose dissolution with ILs has been well developed. And the problems of ILs like high cost, which is obstacle to the industrial scale of ILs application, and the future researches trends and orient of ILs in cellulose/biomass applications, such as the binary systems including complex ILs or solvents, addi­tives and catalysts, will be described more clearly.

The recycle of ILs in an efficient way is also should be well developed. The process of dissolving cellulose or biomass applications in ILs should be optimized to reduce the loss of cellulose or biomass. Binary and ternary system of ILs perhaps will be more efficient for the dissolution of cellulose/biomass, meanwhile, the large scale of synthesis and functional design of ILs with high stabilities and low viscosities will be developed. Considering of the environmental effect and special purposes, bio-degradable ILs and chiral ILs, acid or base enhanced ILs with lower

l, 8-Diazabicyclo[5.4.0]undec-7-enium

saccharinate

1, 8-diazabicyclo [5.4.0] undec-7-enium bis(trifluoromethanesulfonyl)imide 8-Methyl-l,8-diazabicyclo[5.4.0]undec- 7-enium hydrogensulfate 8-Methyl-l,8-diazabicyclo[5.4.0]undec- 7-enium chloride

8-Octyl-1,8-diazabicyclo[5.4.0]undec- 7-enium chloride 1 — Butyl-4-methylpyridinium hexafluorophosphate 1 -Butyl-4-methylpyridinium chloride

38 AMMOENG 110 formate

39 AMMOENG 110 acetate

40 Trihexyltetradecyl phosphonium

dicyanamide

41 AMMOENG 110 dicyanamide

42 Tetrabutylammonium formate

43 N, N,Ntriethyl-3,6,9-trioxadecy-

lammonium acetate

44 Benzyldimethyl(tetradecyl)ammonium

chloride

45 l-(2-Hydroxyethyl)-3-methylimi-

dazolium chloride

46 l-Allyl-2,3-dimethylimidazolium [AdMIM]Br

chloride

47 l-(3,6,9-Trioxadecyl)-3- [Me(OEt)3-Et-

ethylimidazolium Im] [OAc]

aat 298.15K; bat 303.15K; cat 296.65K; dat 293.15K.

Cellulose [123]

Cellulose [123]

Cellulose [123]

Cellulose [22]

Cellulose [22]

Insoluble [115]

Avicel, spruce sulfite, pulp, Cotton linters, cellulose

[22]

Avicel [63]

Avicel [63]

898a [111] Avicel [63]

Avicel [63]

Avicel [63]

Avicel [63, 117]

Spruce sulfite, avicel, pulp, cotton linters [124, 125]

Not mentioned [126]

Avicel, spruce sulfite, pulp, cotton linters[63, 127]

Avicel [63]

r->

Table 1.7 Common ILs used for cellulose/biomass pretreatment ILs Material Solubility Conditions Refs. [BMIM]Cl Cellulose 10 wt% 100 °C [23]a Cellulose 25 wt% Microwave heating 3-5 s [23]a Southern yellow pine (<0.125 mm) 52.6 % 110 °C, 16 h [128]b Wood chips Partially soluble 130 °C, 15 h [62] Silk 9.51 % (w/w) 100 °C [129] Bird feather 23 % 100 °C, 48 h [130] Chitin 10 wt% 110 °C, 5h [131] [AMIM]Cl Cellulose 14.5 wt% 80 °C [132] Ball-milled Southern pine powder 8 wt% 80 °C, 8 h [62] Norway spruce sawdust 8 wt% 110 °C, 8h [62] Pine 26 wt% 24 h [133] Southern pine TMP 5 wt% 130 °C, 8h [62] [EMIM] Cellulose/lignin 4 wt% 75 °C, 1 h [137] [OAc] Southern yellow pine (<0.125 mm) 98.5 % 110 °C, 16 h [128]b Red oak (0.125-0.250 mm) 99.5 % 110 °C, 16 h [128]b Aspen wood 5 wt% 120 C [135] Energy cane bagasse 5 wt% 120 °C [136] [BMIM] [PF6] — Insoluble Microwave [23] [Ch][AA] Sugar Cane Bagasse 5 wt% Magnetic stirrer [134] a0.5-1.0 g of fibrous cellulose, 10 g [Bmim]Cl bWood load (0.50 g) in 10 g IL

viscosity, higher thermal stability would be designed and synthesized by calculat­ing the structure-function relationship or predicting the properties with group contribution method or semi-rational formula.

Acknowledgements This research was supported financially by the Projects of International Cooperation and Exchanges NSFC (No. 21210006), Natural Science Foundation of Beijing of China (No.2131005, No.2132055) and National High Technology Research and Development Program of China (863 Program) (No. 2012AA063001).