Ionic Liquids in Catalytic Biomass Transformation

Utilization of Ionic Liquids in Wood and Wood-Related Applications — A Review

“…Imidazolium is one of the most commonly used cations of ILs, while anions include quite a number such as chloride, hexafluorophosphate, tetrafluoroborate and others. To improve the solubility of cellulose and lignocellulose in ILs, it is important to optimize the suitable anions and cations in ILs, sometimes necessitating structural modifications [52].…”

“…ILs based on polar organic solvents such as dimethyl formamide (DMF), dimethyl acetamide (DMAc), dimethyl imidazolidinone (DMI) or dimethyl sulfoxide (DMSO) and usually coupled with charged species such as LiCl, are frequently used for dissolving cellulose. Methylsulfate imidazolium-based ILs showed excellent results when dissolving softwood Kraft lignins [52].…”

“…Several other methods to extract lignin from lignocellulose have been designed and developed in the past. These include physical (limited pyrolysis and mechanical disruption/comminution), physiochemical (steam explosion, ammonia fiber explosion), and chemical (acid hydrolysis, alkaline hydrolysis, high temperature organic solvent pretreatment, oxidative delignification) methods [52]. The above extraction methods have one main disadvantage; the lignin starts to degrade after a certain amount of lignin is extracted.…”

“…These drawbacks lead researchers to trying to design and develop ILs that are able to dissolve lignin and thus, extracting them from the lignocellulosic biomass with the aim of minimizing lignin degradation. In order to separate lignin from plant constituents using ILs, the ideal IL should possess properties such as: high dissolution capacity for lignin; low melting point; good thermal stability; non-volatile; non-toxic; chemically stable; no lignin decomposition; easy lignin regeneration; low cost and simple process [51,52].…”