WO2014060651A1

WO2014060651A1 - Method of dissolving lignocellulosic materials

Info

Publication number: WO2014060651A1
Application number: PCT/FI2013/050991
Authority: WO
Inventors: Alistair W. T. King; Ashley HOLDING; Ilkka KILPELÄINEN
Original assignee: Metsa Fibre Oy
Current assignee: Metsa Fibre Oy
Priority date: 2012-10-17
Filing date: 2013-10-17
Publication date: 2014-04-24
Anticipated expiration: 2015-04-17
Also published as: WO2014060651A8

Abstract

A solution containing lignocellulose material solvated in an ionic liquid that comprises anions and cations. The cation is selected from substituted phosphonium ions having Formula II, wherein P stands for a phosphonium ion and each R¹, R², R³, and R⁴ is independently selected from optionally substituted, linear or branched hydrocarbyl radicals which form a hydrophobic residue. The anions are derived from a Bronsted acid or mixture thereof. The present ionic liquids are capable of phase separation on mixing with water, which allows for separation of the cellulose from the solution and for recovery and recycling of the ionic liquid.

Description

METHOD OF DISSOLVING LIGNOCELLULOSIC MATERIALS

Technical Field The present invention relates to dissolution of lignocellulosic materials. In particular the invention concerns solutions and dispersions of lignocellulosic materials according to the preamble of claim 1.

The invention also concerns a method according to the preamble of claim 20 of dissolving lignocellulosic material in an ionic liquid.

Further, the invention concerns a method according to the preamble of claim 32 of recovering lignocellulosic material from an ionic liquid. Background Art

Lignocellulosic materials and in particular the cellulosic components thereof, are scarcely soluble in traditional solvents, such as apolar and polar organic compounds. However, it has recently been shown that lignocelluloses can be successfully dissolved in ionic liquids, cf. Haibo Xie, Ilkka Kilpelainen, Alistair King, Timo Leskinen, Paula Jarvi, and Dimitris S. Argyropoulos, "Opportunities with Wood Dissolved in Ionic Liquids" in Tim F. Liebert, Thomas J. Heinze, Kevin J. Edgar (ed.) Cellulose Solvents: For Analysis, Shaping and Chemical Modification ACS Symposium Series, Volume 1033 (2010), p. 343-363. Japanese Patent Application No. 2010220490 discloses a method for treating cellulose- containing material by contacting the cellulose-containing material with a hydrophobic ionic liquid so that the hydrophobic ionic liquid is infiltrated into the cellulose-containing material. Hydrophobic ionic liquids that can be phase separated by water are presented. US Published Patent Application No. 2010081798 relates to a process for preparing glucose from a lignocellulose-comprising starting material, in which this is firstly treated with an ionic liquid and subsequently subjected to an enzymatic hydrolysis. The publication further relates to a process for preparing microbial metabolites, especially ethanol, in which the glucose obtained is additionally subjected to fermentation. WO 2009/105236 discloses compositions and methods that involve ionic liquids and bio mass. Multiphasic compositions involving ionic liquids and a polymer and uses of such compositions for fractioning various components of bio mass are disclosed. Methods of making and using compositions comprising an ionic liquid, biomass, and a catalyst are also disclosed.

Japanese application No. 2012055167 relates to use of an ionic liquid that comprises a phosphonium cation having a hydrophilic carbonyl group substituent in dissolving cellulose.

In their paper "Temperature-responsive ionic liquid/water interfaces: relation between hydrophilicity of ions and dynamic phase change", Yuki Kohno and Hiroyuki Ohno disclose binary ionic liquid/ water mixtures that undergo temperature driven phase change, i.e. lower critical solution temperature (LCST) phase change or upper critical solution temperature (UCST) phase change.

Examples of ionic compounds are imidazolium-based ionic liquids, such as [bmimJCl, (1- butyl-3-methylimidazolium chloride), [emim][OAc] (l-ethyl-3-methylimidazolium acetate) and [emim][Me₂P0₄] (l-ethyl-3-methylimidazolium dimethylphosphate).

The success of the afore-mentioned imidazolium-based ionic liquids at dissolving certain major lignocellulosic components is partly attributable to the weak hydrogen-bond (H- bond) acidities and strong H-bond basicities of the relevant cation and anion combinations. A significant increase in H-bond acidity or decrease in H-bond basicity is suggested to eliminate the capability of these compounds in dissolving lignocellulosic materials.

Interest in these ionic liquids is not only attributable to their ability to dissolve or to swell or to extract (or a combination of two or more of these activities) certain lignocellulosic components but also to the fact that they have little or no vapour pressure, in comparison to non-ionic molecular solvents. This suggests that environmentally benign processes can be developed from them due to vastly reduced volatile organic compound (VOC) emissions and reaction hazards (risk of explosion, fire or corrosion). Summary of Invention

Technical Problem It has been found that the design of fully recyclable and sustainable processes is difficult due to e.g. the instability of existing compounds, their hydrophilicity preventing clean phase-separation and their low volatility meaning that they cannot be distilled.

Imidazolium-based ionic liquids are known to react with lignocellulosic solutes and also decompose thermally at elevated temperatures. This causes problems with recovery and recycling of the ionic liquids.

In fact, the existing state of the art only allows for the processing of the lignocellulosic feedstocks with energy intensive distillation, as the best-case scenario for recycling. Solution to Problem

It is an aim of the present invention to eliminate at least a part of the problem relating to the prior art and to provide novel ionic liquids capable of easy recycling. In particular it is an aim of the present invention to provide ionic liquid mixtures that are capable of partially or completely solvating lignocelluloses (cellulose, hemicelluloses, lignin, extractives, wood itself or other common wood-based fractions).

The invention is based on the finding that substituted phosphonium salts, which can be derived from Bronsted acids, exhibit interesting properties as ionic liquids. In particular, salts of phosphonium ions substituted with hydrophobic hydrocarbyl substituents are capable of undergoing phase separation from water or aqueous solutions. Thus, by adding water or aqueous mixtures to the ionic liquid or electrolyte solutions, formed from substituted phosphonium salts, optionally co-solvents and lignocellulosic, or cellulosic materials, it is first possible to separate the dissolved organic material (lignin, cellulose or polysaccharide) from the solution and then, second, the hydrophobic phosphonium salt can be separated from the remaining components of the solution by phase separation. Based on the above finding in a method of forming a solution, a 0.1 to 50 parts by weight of a lignocellulosic material is contacted with 50 to 500 parts by weight of an ionic liquid that comprises anions and cations of the above kind, optionally in the presence of a co- solvent, in order to solubilise, for example by solvating, the lignocellulosic material. The degree of swelling or solvation of the polysaccharide portion, such as cellulose, can be controlled by addition of the co-solvent, thus offering control over the solvation or extraction of the material. The ionic liquid can then be obtained by recycling phase separated ionic liquid obtained down-stream, optionally complemented with fresh feed. The present tetra-alkyl phosphonium salts have the general formula

[P-R^!R²R³R⁴]-X I wherein

P stands for a phosphonium cation;

R¹, R², R³ and R⁴ together form a hydrophobic residue and are typically selected from a group of hydrophobic hydrocarbyl radicals; and

X is the anion of an organic or inorganic acid.

More specifically, the present solutions are characterized by what is stated in the characterizing part of claim 1.

The present method is characterized by what is stated in the characterizing part of claim 18. The present recovery method is characterized by what is stated in the characterizing part of claim 32 and the use by what is stated in claim 36.

The present invention also provides a use of the method for the production of paper or paper pulp, cardboard, carboxymethyl cellulose (CMC), biofuel, fibres (e.g. in connection with the Lyocell process), threads, polymeric or composite moulds, non-wovens, yarns, films, textiles and adhesives. Advantageous Effects of Invention

Considerable advantages are obtained by the invention. The novel hydrophobic

tetrahydrocarbyl phosphonium salt ionic liquids, in particular when used together with co- solvents, are efficient media for the dissolution and processing of lignocellulosic materials, such as wood, pulp and other lignocelluloses and cellulose raw-materials, which contain cellulose and lignin optionally in combination with other typical components of wood materials and components derived therefrom, such as hemicelluloses and extractives. The said liquids are capable of dissolving H-bonded polymers such as cellulose and even effectively solvate intact wood.

The hydrophobic component in ionic liquids important for cellulose dissolution. Thereby varying the 'hydrophobic' cation portion we can tailor more effective solvents for cellulose and allow for enhanced phase-separation of the ionic liquids.

The present novel phosphonium ions are capable of readily undergoing phase separation from water. It is possible, although this is merely one possibility, that the hydrophobic radicals present on the novel phosphonium ions will enhance phase separation of the ions. The above ionic liquids have high thermal stabilities allowing for wider processing windows and greater kinetic control. They also have wider electrochemical windows than other ionic liquids allowing for redox processes that could be used, for example, to mineralise contaminating components. These ionic liquids have no acidic protons and some structures are phase separable with water (PSILs) allowing for easier recovery.

It has been found that by the use of a co-solvent, solvation of cellulose is achieved up to an ionic liquid co-solvent cut-off limit. Above this limit, cellulose solvation is no longer possible. Below the cut-off limit the viscosities are considerably reduced allowing for a 'kinetic effect' on cellulose dissolution or enhanced diffusion through the bulk wood matrix. The ability to dissolve cellulose is also similarly reduced at a lower co-solvent cutoff limit. Indeed cellulose solvation is aided and controllable by addition of specific co- solvents. The present invention combines the high efficiency of lignocellulose dissolution, extraction and processing in general with the ability to recycle the ionic liquid media by phase-separation. This allows for a wider scope of application of the media to both high value and low value (large-scale) products and processes. The existing state of the art only allows for the processing of the lignocellulosic feedstocks, with energy intensive distillation, as the best-case scenario for recycling.

In addition to the ease of recycling, the present ionic liquids are more thermally stable than the existing structures, commonly used for bioprocessing. The present technology also allows for the tuneable production of different grades of materials, specific to the media in use.

The present invention can also be applied to proteins (e.g. keratin), aramids (e.g. Kevlar) and other polysaccharides (e.g. chitin and chitosan).

Next the invention will be examined more closely with the aid of the following detailed description with reference to a number of exemplifying embodiments.

Brief Description of Drawings

Figure 1 illustrates a prospective process for the dissolution of lignocellulosic materials in phase separable ionic liquids.

Figure 2 shows phase-separation of [Pi₄444]Cl and [P₄₄₄4]C1 from NaCl (aq).

Figure 3 shows phase-separation of [Pi 4444] [O Ac] and [P₄444][OAc] from NaOAc (aq). Figure 4 shows a phase diagram of [P888i][OAc]-DMSO-H₂0 phase-separation.

Figure 5 shows optical microscope images (x 10 magnification) of Bahia PHK pulp in [P₈88i][OAc]:DMSO (60:40 w/w) before (left) and after (right) dissolution at RT.

Figure 6 shows 1H NMR of recovered [Ps88i][OAc] after cellulose dissolution and phase- separation.

Figure 7 shows the IR of regenerated cellulose after ethanol phase-separation from

[P888 i][OAc] :DMSO solution (black) vs cotton (blue).

Figure 8 shows 1H NMR of Bahia PHK pulp pre-dissolved in [P₈₈8i][OAc]:d6-DMSO (10 % w/w), and diluted with d6-acetone. Description of Embodiments

Detailed Description For the purpose of the present technology, the term "lignocellulosic materials" has a broad meaning and is intended to cover a large variety of materials which contain lignocellulosic components (i.e. components formed from differing proportions of lignin, hemicelluloses and cellulose or potentially only one component as such). As already indicated above, raw-materials comprising or derived from, for example, wood are possible. The wood can be in the form of particles (e.g. sawdust), fibres, granules and chips, shavings etc. having a large range of sizes in the range of typically 0.1 to 50 mm (smallest dimension of the particles or part) although these are no absolute limits. Various sources of wood are covered, including deciduous and coniferous species, such as spruce, pine, birch, poplar, aspen, and eucalyptus. However, non-wood materials are also included in the term "lignocellulosic materials" as used in the present context. Such raw- materials can be derived from plants, such as annular or perennial plants, including straw, corn, corn stover, switchgrass, willow, energy hay, Miscanthous . Microbial sources can also be included, such as A. xylinusi.

Another interesting raw-material covered by the above definition is peat which is rich in various carbohydrates, including polysaccharides and other glycans. Further, raw-material sources containing cellulose in pure or relatively pure form are also possible. A typical example is cotton, either in native form or after chemical or mechanical treatment, e.g. mercerized.

All of the above materials can be used as such or mechanically or chemically processed (i.e. as "lignocelluloses-derived products"). Examples of lignocellulose-derived products include chemical, mechanical and chemo mechanical pulps produced of any of the above raw-materials on an industrial or laboratory scale.

Cellulosic pulps, such as chemical pulps and more specifically 'dissolving' pulps, produced by conventional pulping, for example by a kraft, pre-hydro lysis kraft (PHK), sulphite, soda, soda-anthroquinone (S-AQ), pre-hydrolysis soda, or S-AQ, or organosolv cooking processes, are particularly interesting raw-materials.

Another interesting raw-material is formed by lignocellulose fractions obtained by degrading treatments of wood or annular or perennial plants, for example by steam explosion, hydro lytic degradation by water, acid, alkali, ammonia, amines, nucleophiles, enzymes or metal catalysts or mixtures thereof, potentially at increased temperatures and in the presence of oxidants, ozone, oxygen or oxygen-containing gases. Such treatments may not be designed to delignify or mass fractionate the wood, prior to an ionic liquid fractionation but rather to enhance the solubility and fractionability of the wood during the ionic liquid treatment.

Other classes of polysaccharide or materials, not derived from wood, can also be solvated or fractionated, such as chitin or chitosan. These are commonly found in arthropod sources, such as crab or shimp shells, a by-product of the associated food industry. Indeed any polysaccharide rich food industry by-product may benefit from processing with these ionic liquids.

A further class of materials interesting as a raw material is proteins, in particular keratin, found in nature in mammal hair, hooves and feathers, e.g. in wool, in turkey and chicken feathers. Such materials are capable of undergoing treatment with ionic liquids for the extraction and processing of keratin.

Indeed, polymers whose properties rely to a degree on H - bonding between polymer chains, such as Kevlar and other aramid polymers, nylons, silk and DNA may be dissolved and processed using the present ionic liquids.

Naturally it is possible to employ any of the above-mentioned sources of lignocellulosic materials as such or as a combination or mixture of two or more materials of the indicated kind.

Various embodiments described herein provide lignocellulosic solutions that include but are not limited to dispersions in ionic liquids, methods of producing said solutions, methods for the recovery of lignocellulosic solute from said solutions and uses of the recovered solute.

Generally, the term "solution" is used herein to designate any mixture of a substance of the above kind in a liquid which does not separate upon standing for at least 24 hours at room temperature. The "solution" can be clear or turbid. Mostly the present solutions are clear and translucent or even transparent.

Particularly good dissolution or fractionation results are attained by the use of a co-solvent which will assist the ionic liquid in dissolving or swelling of the cellulosic portion of the biomass and potentially facilitating the mass transfer of components. The degree of swelling can be varied by adjusting the amount of co-solvent employed. Such adjustments offer processing advantages. In embodiments wherein no or a controlled amount of co-solvent is used, preferentially non-cellulosic material is extracted from the biomass, the efficiency of which is controllable by co-solvent addition.

In one embodiment a solution contains lignocelluloses or its components and an ionic liquid as solvent comprising cations, preferably substituted phosphonium ions, advantageously a mixture of substituted phosphonium ions, and anions, preferably derived from a Bronsted acid, advantageously derived from a mixture of Bronsted acids

As indicated above, a solution of cellulose in the ionic liquid typically involves an amount of a co-solvent.

Phosphonium ions may be substituted with various groups and in various numbers, and in one embodiment, the cation of the solvent is a substituted phosphonium ion of Formula:

in which R¹, R², R³ and R⁴ typically meets one or several of the following criteria:

- at least two of said hydrocarbyl radicals have more than 7 carbon atoms;

- each hydrocarbyl radical has 4 or more carbon atoms; said hydrocarbyl radicals have a total number of at least 15, advantageously 20, in particular at least 22, for example at least 24 carbon atoms; and said hydrocarbyl radicals contain additional functionalities, for example unsaturation, heteroatoms or carboxylates

Non-limiting examples of tetra-alkyl phosphonium cations are illustrated to clarify the meaning of the general formula from a structural perspective.

In one preferred embodiment, each independently-selected hydrocarbyl or substituted hydrocarbyl radical of Formula II contains preferably 4 or more carbon atoms, more preferably 5 to 40 carbon atoms, most preferably 6 to 14 carbon atoms.

In another preferred embodiment, the hydrocarbyl radicals are selected such that at least one has 14 carbon atoms or more. Typically, the remaining hydrocarbyl radicals have at least 4 carbon atoms, preferably 5 carbon atoms or more.

In still a further preferred embodiment, at least two, preferably three, of the hydrocarbyl radicals are selected such that they have 8 or more carbon atoms, and the remaining hydrocarbyl radicals have at least one carbon atom, preferably 1 to 8 carbon atoms. In a preferred embodiment the hydrocarbyl radicals R¹, R², R³ and R⁴ are independently selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, triacontyl, hentriacontyl, dotriacontyl, tritriacontyl, tetratriacontyl, pentatriacontyl, hexatriacontyl, heptatriacontyl, octatriacontyl, nonatriacontyl, tetracontyl. The hydrocarbyl radicals can be linear or branched. Thus, for example, iso- or tert-isomers of the above listed alkyl groups (or the alkyls having more than 2 carbon atoms) are included equally. The hydrocarbyl can also contain substitutents. Preferred substitutents are of a character, which does not significantly impair the hydrophobic properties of the hydrocarbyl residue as a whole. However, by substitution it is possible to tune the hydrophobic properties or increase the lignocellulose solvating capacity. Examples of hydrophobic substituent groups include fluoro and other halo groups. Unsaturated chains may be present and additional lignocellulose solvating functionalities may be carboxylates amines or other basic functionalities containing heteroatoms. Examples of suitable compounds of Formula II include P14,6,6,6, P8,8,8,8 and P8, 8,8,1, wherein the numerals stand for the number carbon atoms in the hydrocarbyl radicals. Preferably, there are at least 15 to 20 carbon atoms in toto.

The anions of phosphonium salts can be derived from various Bronsted acids both organic and inorganic and thus in one embodiment the anion of the ionic liquid solvent is derived from a Bronsted acid of general formula HX, X being an anion selected from the group halide, nitrate, nitrite, phosphinate, carboxylate, sulphonate, organosulphates,

organosulfonates, hydride, fluoride, chloride, bromide, iodide, cyanide, hydroxide, hypochlorite, hypobromite, hypoiodite, chlorite, bromite, iodite, hydrogen sulfite, chlorate, bromate, iodate, perchlorate, perbromate, periodate, hydrogen carbonate, hydrogen sulfate, dihydrogen phosphate or other phosphates, such as mono- or dialkyl phosphates, substituted phosphonates, acetate, other carboxylates, such a propionate or longer chain carboxylates, permanganate, thiocyanate, hydrogen oxalate, hydrogen sulfide, amide or combinations thereof. A co-solvent or mixture of co-solvents for the purpose of increasing the solubility of the lignocelluloses is added to the ionic liquid solvent in one example. It is advantageous to use a co-solvent or mixture of co-solvents, which is miscible with the ionic liquid.

In a preferred example the co-solvent or co-solvents are aprotic and polar. In one example the co-solvent or co-solvents may be selected from the group consisting of

dimethylsulfoxide (DMSO), 1 ,3 dimethyl-2-Imidazolidinone (DMI), l ,3-dimethyl-3, 4,5,6- tetrahydro-2(lH)-pyrimidinone (DMPU), dichloromethane (DCM), Tetrahydrofuran (THF), ethyl acetate, acetone, acetonitrile, dimethylformamide (DMF), dimethylacetamide (DMA), 1 , 1 ,3,3-tetramethylurea (TMU), ethanol, hexamethylphosphoramide (HMPA), acetone, dioxane, and pyridine. Water and other protic solvents such as alcohols and ammonia may be tolerated at concentrations below that which causes phase-separation of the ionic liquid.

Generally it is preferred that the co-solvent is miscible with the IL. In one embodiment, it is freely soluble in the ionic liquid.

The amount of co-solvent and the amount of solute in the ionic liquid solvent can be varied so that in one example the content of co-solvent amounts to between 1 and 50%, preferably between 5 and 30%>, or advantageously between 10 and 20%> of the total weight of the solution and the content of the solute amounts to between 1 and 40%, preferably between 5 and 35%), advantageously between 10 and 30%> of the total weight of the solution.

The present technology also provides methods for dissolving lignocellulosic materials and components thereof. As mentioned above, dissolution is preferably attained by the use of a co-solvent, which will assist the ionic liquid. The dissolution action will include dissolving or swelling of the cellulosic portion of the biomass. The degree of swelling can be varied, by adjusting the amount of co-solvent employed. In embodiments wherein no or a controlled amount of co-solvent is used, non-cellulosic material, such as various polysaccharides and lignin and components thereof, is extracted from the biomass. According to the present technology, the lignocellulosic materials are contacted with an ionic liquid that comprises anions and cations, preferably substituted phosphonium ions, advantageously a mixture of substituted phosphonium ions, and anions, preferably derived from a Bronsted acid, advantageously derived from a mixture of Bronsted acids, under conditions that are conducive to at least partial dissolution of the cellulosic components of the lignocellulosic materials.

In one such embodiment the cation of the ionic liquid solvent in the method is a substituted phosphonium ion of Formula II in which R¹, R², R³ and R⁴ have the same meaning as above.

Just as was discussed above, in an example, the hydrocarbyl radicals of the phosphonium ion of the ionic liquid solvent used in the method are independently selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, triacontyl, hentriacontyl, dotriacontyl, tritriacontyl, tetratriacontyl, pentatriacontyl, hexatriacontyl, heptatriacontyl, octatriacontyl,

nonatriacontyl, tetracontyl, linear and - for species having more than 2 carbon atoms - branched hydrocarbyl radicals being equally included in the group.

In a further example, the anion of the ionic liquid solvent of the method is derived from a Bronsted acid of general formula HX, wherein X is an anion having the same meaning as above.

A co-solvent or mixture of co-solvents for the purpose of increasing the solubility of the lignocelluloses is added to the ionic liquid solvent in one example of the method. In a preferred example the co-solvent or co-solvents are aprotic and polar. In one example, the co-solvent or co-solvents are selected from the group described above. The amount of co-solvent and the amount of solute in the ionic liquid solvent can be varied in the method so that in one example the content of co-solvent amounts to between 1 and 50%, preferably between 5 and 30%, or advantageously between 10 and 20%> of the total weight of the solution and the content of the solute amounts to between 1 and 40%, preferably between 5 and 35%, advantageously between 10 and 30%> of the total weight of the solution.

A further embodiment provides a method wherein the at least partial dissolution of the cellulosic component will produce a solution as described in any of the above

embodiments.

For the sake of completeness it should be pointed out that polyoxometalates (POMs) and other redox catalysts can be used in the present technology for mineralising residual lignin in the ionic liquid. Phosphonium ionic liquids give the advantage that they have wide electrochemical windows so are better able to withstand the oxidative degradation of lignin with such catalysts.

In a particular embodiment "lignocellulosic solute", which expression also covers solute of components leached out from the lignocelluloses material, is recovered from an ionic liquid of the kind discussed above, by a method comprising phase separation.

For the phase separation of the ionic liquid from the solution, a phase separation medium is used. It can be selected from the group of liquid polar media, such as water, aqueous solutions, including aqueous or alcoholic solutions of inorganic or organic salts or mixtures thereof, lower alcohols, e.g. methanol, ethanol or isopropanol, aqueous solutions of lower alcohols, carbon dioxide, optionally in supercritical condition, and liquid ammonia. Water and aqueous solutions of salts are particularly preferred embodiments. The medium for the phase separation of the ionic liquid is partially miscible with the ionic liquid. In a particularly preferred embodiment, the medium is miscible with the co-solvent, discussed above. Suitably, the said medium is partially miscible with both the ionic liquid and the co-solvent, which together form an electrolyte. Increasing the amount of the co- solvent or indeed adding a second co-solvent will then cause the ionic liquid to undergo phase separation.

In a first preferred embodiment, water is used as phase separation medium. By the water recycling of liquid stream and work-up and purification are simplified. In a second preferred embodiment, water-containing salt is used as phase-separation medium. Such a medium will be efficient in achieving phase-separation when miscibility of the ionic liquid with the medium is weak. Typically, the less strong the hydrophobic character of the hydrocarbyl residue, for example when the total carbon number of the residue is about 15 to 20, the more efficient is the phase-separation carried out by using aqueous salt solutions. The concentration of the aqueous salt solutions used as the phase separation medium is approximately indirectly proportional to the temperature at which phase separation occurs, i.e. increasing temperature allows for phase separation at lower salt concentrations.

In one example of the method comprising phase separation with water, in particular water substantially free from salts, the cation of the ionic liquid is a substituted phosphonium ion of Formula PfR¹ R² R³ R⁴], in which R¹, R², R³ and R⁴ are preferably independently- selected hydrocarbyl or substituted hydrocarbyl radicals containing preferably 4 or more carbon atoms, more preferably 5 to 40 carbon atoms, most preferably 6 to 14 carbon atoms.

In another example of the method comprising phase separation with an aqueous solution of salt, the cation of the ionic liquid is a substituted phosphonium ion of Formula PfR¹ R² R³ R⁴], in which R¹, R², R³ and R⁴ are preferably independently-selected hydrocarbyl or substituted hydrocarbyl radicals at least 2, preferably at least 3, containing more than 7 carbon atoms, more preferably 6 to 40 carbon atoms, most preferably 6 to 14 carbon atoms, and one or two hydrocarbyl radicals containing 1 to 8 carbon atoms.

In an example of the method comprising phase separation with water, the hydrocarbyl radicals of the phosphonium ion of the ionic liquid solvent used in the method are of the kind discussed above.

In a further example of the method comprising phase separation with water, the anion of the ionic liquid solvent of the method is derived from a Bronsted acid of general formula HX, wherein X has the same meaning as above.

In a yet further example of the method comprising phase separation with water, at least a part of the dissolved lignocellulosic materials is recovered. As will be discussed below, phase separation can be achieved generally by changing temperature or pressure, or by increasing the amount of phase separation medium added, or increasing the hydrophilic salt concentration. Typically, the temperature is increased to, at a maximum, the boiling point of the phase separation medium at the prevailing pressure.

Turning now to the attached drawing, it can be noted that Figure 1 illustrates one exemplary embodiment of a process for the dissolution of lignocellulosic materials in phase separable ionic liquids. The following reference numerals are used in the figure:

1 lignocellulose material, such as dissolving pulp or wood

2 DMSO

3 Ionic Liquid

4 Cellulose

5 Water

6 Regenerated cellulose + [Ρ·^¾¾⁴]Χ, water and DMSO

7 Regenerated Cellulose or Pulp

8 ⁺[P-R' ²R³R⁴]

9 Water and DMSO

According to the embodiment shown in Figure 1 , lignocellulosic material 1 is contacted with an ionic liquid 3 and an optional co-solvent 2 to give, by solvation, a solution of lignocellulose, ionic liquid and co-solvent. The contacting can be carried out at ambient pressure and at ambient temperature, the latter denoting room temperature, i.e. in excess of 15 and up 25 °C. It is also possible to carry out the contacting step at conditions outside said ranges, for example at a pressure higher or lower than the ambient pressure and at a temperature of -40 °C and up to 15 °C or at a temperature above 25 °C and up to the boiling point of the medium, i.e. the ionic liquid or co-solvent or mixture of ionic liquid and co-solvent.

The contacting can be enhanced by subjecting the components to mixing, preferably at turbulent conditions. The contacting time is typically 0.1 to 48 hours, in particular about 0.2 to 24 hours, for example about 0.5 to 15 hours, or 1 to 12 hours. The contacting step gives rise to solvation of the lignocellulose or cellulose material by the phosphonium cations and counteranions. The co-solvents, if any, will make the solvation action more efficient or tunable. The solution thus obtained can be recovered. Generally, the solution is stable which opens up for the possibility of transporting the dissolved cellulose or lignocelluloses matter to another facility wherein it is subjected to the following steps.

The dissolved matter can be separated from the solution by adding a precipitant. Typically, and preferably, water or an aqueous solution is added. Examples of aqueous solutions include ethanolic and methanolic solutions and similar solutions of water and miscible organic solvents, preferably polar agents.

Thus, as shown in Figure 1, on addition of water 5, cellulose is regenerated from the solution giving a mixture of regenerated cellulose, ionic liquid, water and co-solvent 6.

Generally, the amount of water or aqueous solution added is 0.1 to 50 parts by weight, in particular about 1 to 40 parts by weight. In an embodiment, the amount of water or aqueous solution added is roughly the same as that of the ionic liquid, i.e. the weight ratio of water (or aqueous solution) to ionic liquid is about 1 :20 to 20 : 1 , in particular about 1 : 10 to 10:1.

The addition of water or aqueous solution can be carried out at ambient pressure and at a temperature of about 15 to 25 °C, although partial vacuum or, preferably, increased pressure can also be used.

The dissolved matter is precipitated and the precipitate is then separated for example by settling, filtering or by centrifugation. In particular, the mixture is filtered and the residual regenerated cellulose 7 is washed, for example with ethanol, which is then fed into the ionic liquid 3.

The remaining components, i.e. the remaining of ionic liquid, co-solvent and water 6, are subjected to phase-separation. Phase-separation can be achieved by changing temperature or pressure, i.e. by increasing or decreasing the temperature or pressure, or increasing the amount of water or aqueous solution added, or increasing the hydrophilic salt concentration. Typically, the temperature is increased to at least 40 °C, in particular up to the boiling point of water at the prevailing pressure, e.g. 100 °C. The separated ionic liquid 8 is then recycled 3 for the solvation of more lignocellulosic material 1. The water and co-solvent 9 are similarly recycled 2, 5.

The recycled ionic liquid can be used for contacting with fresh lignocellulosic material in order to prepare a solution. Typically, there are some minor losses of ionic liquid which have to be made up for and, optionally, some fresh feed of ionic liquid is therefore also be added although that is not mandatory.

Generally, when operating the process on a continuous basis, the molar ratio of recycled ionic liquid to fresh feed amounts to 100:0.1 to 100:50, in particular 100: 1 to 100: 10 which indicates the efficiency of phase separation of the solutions and of the recovery of the ionic liquid of the process.

The following non-limiting examples illustrate the invention: Examples Materials

Trioctylphosphine (Psss) was purchased from CYTEC. Phosphonium salts (CYPHOS 443 W, CYPHOS IL101 , CYPHOS 3453 W) were a gift from CYTEC. All other reagents were purchased from Sigma- Aldrich. All reagents were used, without further purification.

Synthesis of methyltrioctylphosphonium acetate, [Psssi] [OAc] [Ps88i][OAc] was synthesised according to previously published methods. [1]

[1] (M. Fabris, V. Lucchini, M. Noe, A. Perosa, andM. Selva, Chemistry (Weinheim an der Bergstrasse, Germany), 2009, 15, 12273-82.) Trioctylphosphine (Psss, 350 ml, 7.85x10 1 mol) was charged into a 2L Parr reactor under inert atmosphere. Dimethylcarbonate (DMC, 700 ml, 1.73x1ο¹ mol) and methanol (700 ml) were added to the reaction vessel. The reaction mixture was stirred at 140 °C, under inert atmosphere for 24 hr between 20-40 bar. Excess methanol and DMC were removed at reduced reduced pressure, forming the product, [P888i][MeC0₂] a pale yellow viscous solution. To a methanolic solution of [P888i][MeC0₂] (197.34, 4.1 lxlO^"1 mol) an equimolar amount of acetic acid (glacial) was added, dropwise and with stirring, until the reaction went to completion. Excess methanol was evaporated at reduced pressure, and the resulting product, the ionic liquid [Ps88i][OAc], was dried on a high-vacuum rotovap to remove traces of methanol and water. 1H NMR (300 MHz, CDC1₃) δ 7.26, 2.38, 2.07, 2.02, 1.91 , 1.46, 1.24, 0.85.

Synthesis of tetraoctylphosphonium chloride, [PssssJCl

Trioctyl phosphine (Psss, 16.62 g, 0.0448 mol) was added to a round bottom flask followed by an excess of 1-chlorooctane (10 ml, 0.0588 mol), added in small portions. The reaction was stirred overnight, under inert atmosphere, at 145 °C. The product was dried under high vacuum (24 hr, 70 °C) and was obtained as a light yellow oil (22.7 g, 98% Yield). 1H NMR (300 MHz, CDC1₃) δ 2.31 , 1.37, 1.15, 0.75; ¹³C NMR (75 MHz, CDC1₃) δ 31.79, 30.85, 29.06, 25.29, 22.02, 19.33, 18.71 , 14.14.

Synthesis of tetrabutylphosphonium acetate, [P4444] [OAc] [P₄444]C1 (CYPHOS 443W, 80% w/w in H₂0) was dried on a high-vacuum rotary evaporator (3 hr, 70 °C). Silver acetate (7.71 g, 0.0466 mol) was weighed into a conical flask and isopropanol/H₂0 (300 ml, 1 : 1) was added. [P4444]C1 (13.73 g, 0.0466 mol) was added to the reaction mixture and stirred overnight, under inert atmosphere. The precipitate was filtered through celite and the filtrate, was evaporated down on a rotary evaporator. Further drying took place in a high- vacuum rotary evaporator (12 hr, 70 °C) and the product was obtained as a pale-yellow crystalline material (13.03 g, 87%> yield). 1H NMR (300 MHz, CDC1₃) δ 2.20, 1.73, 1.32, 1.05, 0.77. ¹³C NMR (75 MHz, CDC1₃) δ 176.49, 24.13, 23.92, 19.05, 18.42, 13.52. Synthesis of tetrabutyl(tetradecyl)phosphonium acetate, [P14444] [OAc]

[Pi444₄]Cl (26.5 g, 6.10x10 2 mol) was charged into a round-bottom flask, with methyl acetate (10 ml, 1.20x10 1 mol) and isopropanol (20 ml). Potassium hydroxide (70.3 ml, 0.868 M in isopropanol) was added slowly, in aliquots of 10 ml. The mixture was stirred over and after chilling in an ice bath, was filtered through celite. The filtrate solvent was evaporated using a rotary evaporator and the product dissolved into cold acetone (10 ml). The product mixture was stirred over an ice bath, and solution filtered through celite to remove further salt precipitation. The solvent was evaporated at reduced pressure and the product transferred to a high- vacuum rotary evaporator, for 24 hr at 70 °C. The product was a yellow-orange viscous liquid (27.1 g, 97% yield). 1H NMR (300 MHz, CDC1₃) δ 7.26, 2.45, 1.93, 1.49, 1.24, 0.96, 0.87.

Phase Diagrams of Water Soluble ILs and Salt Solutions (Figures 2 & 3) Example, Phase Diagram of [Pi444]Cl, NaCl, and Water:

A glass sample vial and magnetic stirrer was placed onto a hot-plate, with a thermocouple suspended into the vial, for precise temperature measurement. [Pi₄44₄]Cl (1 ml in H₂0, 1 : 1) was syringed into the vial containing NaCl (0.359 g) and distilled water (0.5 ml) and was vigorously agitated until the mixture became cloudy. The mixture was allowed to reach room temperature. Aliquots of water (0.1 ml) were added to the stirring mixture until the 'clear point' as obtained, or when the two phases formed one homogeneous clear phase. Thereafter, the temperature is increased slowly, until the 'cloud-point' is reached and the phase separation temperature recorded. The results are plotted on Figure 1.

Phase Diagrams of Water Insoluble ILs and Co-Solvents (Figure 4)

Example, Phase Diagram of [P₈₈8i]OAc, DMSO and Water:

For each phase diagram, a series of solutions with varying compositions of ionic liquid and an organic co-solvent were made. In a typical experiment, a fixed amount of the ionic liquid and co-solvent were prepared, after which the solution was agitated with a mechanical vortexer. Phase boundaries were determined by the addition of the third component, water, in 0.005 ml portions until the 'cloud point' was reached. The residual water content in the ionic liquid and the co-solvent was measured with Karl-Fischer titration (see 'Determination of Water Content') and was accounted for in the cloud-point values. Additional measurements were taken to determinate the 0 % co-solvent boundary points and composition of the phases. These included Karl-Fischer titration of the upper ionic liquid rich layer, from a phase-separated mixture of a known amount of ionic liquid and water, for the minimum w/w % of water and DMSO content of the ionic liquid-rich layer required for phase-separation. In addition, a 1H NMR spectrum of the lower water- rich layer was taken, from which relative integration values were used to determine the w/w % composition of ionic liquid and co-solvent in water.

Dissolution of Cellulosic Pulp in Ionic Liquids In a typical dissolution experiment, a portion of the ionic liquid, or ionic liquid and co- solvent mixture, was charged into a pre-weighed screw cap vial, after which any additional co-solvents were added. A known weight of cellulose pulp was added to the ionic liquid, or ionic liquid and co-solvent mixture, along with a magnetic stirrer-bar, and the mixture agitated in a mechanical vortexer to ensure distribution of the cellulose pulp throughout the solvent. The mixture was stirred mechanically, and in a thermostated oil-bath for dissolution tests conducted above room temperature.

Dissolution tests were conducted at 100 °C, 60 °C, and at room temperature, with a range of ionic liquid and co-solvent compositions, and with varying weight percentages of pulp or cellulose. In all cases without DMSO, as co-solvent, there was no cellulose dissolution. For the dissolution of MCC, above 50% DMSO seemed to give no dissolution, as an upper cutoff limit.

Co-solvent screening was carried out with a fixed w/w %> of co-solvent and w/w %> of cellulose

Table 1 shows the results of the dissolution of Cellulose in [P₈88 i][OAc] Table 1: Dissolution of microcrystalline cellulose (MCC) and Bahia eucalyptus pre- hydrolysis kraft pulp (PHK) with [P₈₈₈₁] [OAc] :DMSO mixtures. Increasing '*' represents more efficient dissolution as determined by the speed of dissolution, '-' represents no dissolution. 'OES' refers to Organic electrolyte solution'.

[P_mi][OAc] DMSO Pulp in OES Dissolution Temp. Pulp (% w/w) (% w/w) (% w/w) (°C) (Cellulose)

90.0 0.0 10 -

89.5 0.5 10 ** 60 MCC

88.4 1.6 10 *** 60 MCC

86.9 3.1 10 **** 60 MCC

85.0 5.0 10 **** 60 MCC

82.7 7.3 10 **** 60 MCC

76.5 13.5 10 ***** 60 MCC

66.6 23.4 10 ***** 60 MCC

52.8 37.2 10 ***** 60 MCC

32.6 57.4 10 - 60 MCC

19.9 70.1 10 - 60 MCC

4.8 85.2 10 - 60 MCC

90.0 0.0 10 - 60 PHK

67.0 11.8 21.2 * 60 PHK

73.0 12.8 14.1 ** 60 PHK

79.0 13.9 7.1 **** 60 PHK

82.0 14.4 3.5 ***** 60 PHK

58.6 20.6 20.8 * 60 PHK

63.7 22.4 13.9 *** 60 PHK

68.9 24.2 6.9 **** 60 PHK

71.4 25.1 3.5 ***** 60 PHK

46.5 32.7 20.8 * 60 PHK

50.6 35.6 13.9 *** 60 PHK

54.6 38.4 6.9 **** 60 PHK

56.7 39.9 3.5 ***** 60 PHK

Table 2 shows the results for dissolution of Cellulose and Lignin with Phosphonium Ionic Liquids.

Table 2. Lignin and microcrystalline cellulose (MCC) dissolution into phosphonium ionic liquids.

Dissolution of Lignin in Ionic Liquids

Using the same procedure as the cellulose dissolution tests (described above) samples of 5%w/w spruce dioxane-acido lysis lignin dissolved in all ionic liquids (numbers) including chloride and acetate forms of the same cation. The lignin samples dissolved rapidly at 100 °C in under 10 min.

Optical Microscopy of Ionic Liquid, Co-Solvent, and Cellulose Solutions [P888 i][OAc]:DMSO (0.475 g, 9: 1 w/w) was mixed, by vortexing, with Bahia eucalpytus pre-hydro lysis kraft pulp (PHK, 25 mg, DP 1100) and the resulting mixture transferred quickly to a microscope slide. Optical images were taken at this stage, with varying degrees of magnification, showed the presence of cellulose fibres. The ionic liquid, cellulose and co-solvent mixture was left stirring, at room temperature until a clear, viscous solution was observed. Optical images taken at this stage showed the absence of cellulose fibres, at all degrees of magnification. For results, cf. Figure 6.

NMR spectroscopy of Dissolving Pulp in [P₈₈₈i] [OAc]/DMSO solution By dissolving Bahia PHK (10% w/w) into [P₈₈8 i][OAc]:d6-DMSO (1 : 1), a "stock" solution of cellulose in ionic liquid was made. The solution was diluted with d6-acetone (1 :2) and a 1H NMR spectrum was collected (Figure 10), showing well-defined and polymeric cellulose backbone peaks. Regeneration of Cellulose

Methanol, ethanol, isopropanol, water, water:alcohol, saline (NaCl, NaOAc) aqueous solutions and other anti- solvents can be used to regenerate cellulose from the ionic liquid- co-solvent solutions. In a typical cellulose regeneration experiment, ethanol (2 volume equivalents) was added to the container containing the ionic liquid, co-solvent, and cellulose solution. After vigorous mixing, the mixture was left to stir for 2 hr, after which the regenerated cellulose pulp was vacuum filtered, and washed with further ethanol. IR Spectroscopy

FTIR spectra of the regenerated cellulose pulp was taken, after drying of the regenerated pulp at 80 °C overnight. The IR spectrum of the regenerated pulp was compared with cotton, showing no bands arising from acetyl groups. (Figure 8), indicating removal of the ionic liquid from the regenerated pulp.

Phase-Separation of the Ionic Liquid following Cellulose Regeneration Following regeneration of cellulose with typically an ethanolic or aqueous ethanolic solution, the mixture of ionic liquid [Ps88i][OAc], ethanol, DMSO and water, was evaporated at reduced pressure to remove and recycle the low-boiling ethanol. For water immiscible ionic liquids, water is added inducing phase-separation. The ionic liquid and aqueous layers can be isolated and recycled. Additional DMSO can be recovered from the aqueous layer. For phase-separation of ionic liquids that are miscible with water, saline solutions can be used. Typically NaCl for ionic liquids containing chloride anions and NaOAc for ionic liquids containing acetate anions. Matching the anions of the salts prevents contamination of the hydrophilic and hydrophobic fractions After phase- separation the ionic liquids are dried using high vacuum and/or temperature to remove final traces of water. An NMR of [Ps88i][OAc] following pulp dissolution and regeneration with ethanol- water is given in Figure 7.

Dissolution and Precipitation of Wood Using the same procedure as the cellulose dissolution tests (described above) two samples of autohydrolysed Spruce wood (5% w/w and 10% w/w, P-factor 500) were dissolved in ionic liquids [Ps88i][OAc] and [Pi₄₄44][OAc], each containing DMSO co-solvent (10% w/w). The resulting solutions were viscous and dark brown with no solid particles left. The materials were precipitated with ethanol. Industrial Applicability

The recovered lignocellulosic materials can be put to several uses and one embodiment provides a use of the method comprising phase separation with water for recovering cellulose from solution for the production of paper/ paper pulp/ cardboard/ carboxymethyl cellulose (CMC)/ bio fuel/ textiles/ adhesives etc.

Citation List

Patent Literature Jo Sonjin et al. JP2010220490 - Method for Producing Hydrolysis Product from

Cellulose-Containing Material

Balensiefer Tim et al. US2010081798 - Method for Producing Glycose Vy Enzymatic Hydrolysis of Cellulose that is Obatained from Material Containing Ligno cellulose Using an Ionic Liquid that Comprises a Polyatomic Anion

Rahman Mustafizur et al. WO2009105236 Ionic Liquid Systems for the Processing of Biomass, their Components and/or Derivatives, and Mixtures Thereof Toyota Central Res and Dev. JP2012055167 - Method For Treating Cellulose-Containing Material and Use Thereof

Non Patent Literature Haibo Xie, Ilkka Kilpelainen, Alistair King, Timo Leskinen, Paula Jarvi, and Dimitris S. Argyropoulos, "Opportunities with Wood Dissolved in Ionic Liquids" in Tim F. Liebert, Thomas J. Heinze, Kevin J. Edgar (ed.) Cellulose Solvents: For Analysis, Shaping and Chemical Modification ACS Symposium Series, Volume 1033 (2010), p. 343-363. Yuki Kohno and Hiroyuki Ohno, "Temperature-responsive ionic liquid/water interfaces: relation between hydrophilicity of ions and dynamic phase change" Phys. Chem. Chem. Phys., 2012, 14, 5063-5070

Claims

1. A solution containing lignocellulose material or its components solvated in an ionic liquid that comprises anions and cations, said cation being selected from substituted phosphonium ions having Formula II

^[R¹ R² R³ R⁴] II wherein

+P stands for a phosphonium ion and each R¹, R², R³, and R⁴ is independently selected from hydrocarbyl radicals jointly forming a hydrophobic residue;

said anions being derived from a Bronsted acid or a mixture of two or more such ions, and said ionic liquid being capable of phase separation on mixing with a phase separation medium.

2. The solution according to claim 1, wherein the phase separation medium is selected from the group of polar liquid media, such as water, aqueous solutions, including aqueous solutions of inorganic or organic salts or mixtures thereof, carbon dioxide, optionally in supercritical condition and liquid ammonia, said liquid media optionally being miscible with the ionic liquid.

3. The solution according to claim 1 or 2, wherein R¹, R², R³ and R⁴ meets one or several of the following criteria:

- at least two of said hydrocarbyl radicals have more than 7 carbon atoms;

- each hydrocarbyl radical has 4 or more carbon atoms;

- said hydrocarbyl radicals have a total number of at least 15, in particular at least 20, advantageously at least 22, for example at least 24 carbon atoms; and

- any of said hydrocarbyl radicals containing additional functionalities, for example unsaturation, heteroatoms or carboxylates.

4. The solution according to any of claims 1 to 3, wherein each R¹, R², R³ and R⁴ is independently a linear or branched hydrocarbyl or substituted hydrocarbyl radical, at least two of said radicals containing more than 5 carbon atoms, preferably 6 to 40 carbon atoms, advantageously 6 to 14 carbon atoms.

5. The solution according to any of claims 1 to 4, wherein at least two, preferably three, of the hydrocarbyl radicals are selected such that they have 8 or more carbon atoms, and the remaining hydrocarbyl radicals have at least one carbon atom, preferably 1 to 8 carbon atoms.

6. The solution according to any of claims 1 to 5, wherein at least three of the substituents R¹, R², R³ and R⁴ are linear or branched hydrocarbyl radicals having more than 7 carbon atoms.

7. The solution according to any of claims 1 to 6, wherein each hydrocarbyl radical is independently selected from alkyl of the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, triacontyl,

hentriacontyl, dotriacontyl, tritriacontyl, tetratriacontyl, pentatriacontyl, hexatriacontyl, heptatriacontyl, octatriacontyl, nonatriacontyl, and tetracontyl, said alkyl groups containing more than 2 carbon atoms optionally being branched and each hydrocarbyl radical being optionally substituted.

8. The solution according to any of the preceding claims, wherein the anion is derived from a Bronsted acid of Formula III

HX III wherein X is an anion selected from the group consisting of halide, in particular fluoride, chloride, bromide, iodide, nitrate, nitrite, phosphinate, carboxylate, sulphonate,

organosulphates, organosulfonates, hydride, cyanide, hydroxide, hypochlorite,

hypobromite, hypoiodite, chlorite, bromite, iodite, hydrogen sulfite, chlorate, bromate, iodate, perchlorate, perbromate, periodate, hydrogen carbonate, hydrogen sulfate, dihydrogen phosphate, substituted phosphates, phosphonates, acetate, propionate, other longer-chain carboxylates, permanganate, thiocyanate, hydrogen oxalate, hydrogen sulfide, amide and combinations thereof.

9. The solution according to any of the preceding claims, further containing a co-solvent or a mixture of co-solvents, in particular an aprotic co-solvent or mixtures thereof.

10. The solution according to claim 9, wherein the co-solvent is miscible with the ionic liquid.

1 1. The solution according to any of the preceding claims, wherein the ionic liquid is used with a co-solvent, and the ionic liquid and the co-solvent form an electrolyte.

12. The solution according to claim 1 1 , wherein the phase separation medium is being miscible with the electrolyte.

13. The solution according to any of claims 9 to 12, wherein the co-solvent is selected from dimethylsulfoxide (DMSO), 1 ,3 dimethyl-2-Imidazolidinone (DMI), l ,3-dimethyl-3, 4,5,6- tetrahydro-2(lH)-pyrimidinone (DMPU), dichloromethane (DCM), tetrahydrofuran (THF), ethyl acetate, acetone, acetonitrile, dimethylformamide (DMF), hexamethylphosphoramide (HMPA), acetone, dioxane, and pyridine and mixtures thereof.

14. The solution according to any of claims 9 to 12, wherein water and other protic solvents, such as alcohols and ammonia, are tolerated at concentrations below that which causes phase-separation of the ionic liquid.

15. The solution according to any of claims 9 to 14, wherein the amount of the co-solvent is between 1 and 50 %, preferably between 5 and 30 %, advantageously between 10 and 20 %, calculated from the total weight of the ionic liquid and co-solvent(s).

16. The solution according to any of the preceding claims, wherein the amount of the lignocellulose material is between 1 and 40 %, preferably between 5 and 35 %,

advantageously between 10 and 30 %, of the total mass of the solution.

17. The solution according to any of the preceding claims, wherein the lignocellulose material comprises wood, annular or perennial plant, and materials derived from any of these by mechanical or chemical processing, for example wood chips, sawdust, cellulose pulp, plantery milled wood, autohydrolysed wood, agricultural waste and recycled lignocellulosics, including recycled paper, cardboard and wood, in particular the lignocellulosic material comprises decomposed or degraded wood or wood pulp produced by mechanical, chemimechanical or chemical processing, preferably chemical pulp, for example chemical pulp having a cellulose content of 90 % by mass or more.

18. A method of forming a solution of a lignocellulosic material comprising contacting 0.1 to 50 parts by weight of the lignocellulosic material with 50 to 500 parts by weight of an ionic liquid that comprises anions and cations, said cation being selected from substituted phosphonium ions having Formula II

⁺P[R^! R² R³ R⁴] II wherein

⁺P stands for a phosphonium ion and each R¹, R², R³, and R⁴ is independently selected from optionally substituted hydrocarbyl radicals, said radicals together forming a hydrophobic residue;

19. The method according to claim 18, comprising solvating the lignocellulosic material with the ionic liquid to form a solution.

20. The method according to claim 18 or 19, wherein in Formula II R¹, R², R³ and R⁴ meets one or several of the following criteria:

- at least two of said hydrocarbyl radicals have more than 7 carbon atoms;

- each hydrocarbyl radical has 4 or more carbon atoms;

21. The method according to claim 20, wherein the hydrocarbyl radicals are independently selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, triacontyl, hentriacontyl, dotriacontyl, tritriacontyl, tetratriacontyl, pentatriacontyl, hexatriacontyl, heptatriacontyl, octatriacontyl, nonatriacontyl, and tetracontyl.

22. The method according to any of claims 18 to 21 , wherein the anion is derived from a Bronsted acid of Formula III HX III wherein X is an anion selected from the group consisting of halide, nitrate, nitrite, phosphinate, carboxylate, sulphonate, organosulphates, organosulfonates, hydride, fluoride, chloride, bromide, iodide, cyanide, hydroxide, hypochlorite, hypobromite, hypoiodite, chlorite, bromite, iodite, hydrogen sulfite, chlorate, bromate, iodate, perchlorate, perbromate, periodate, hydrogen carbonate, hydrogen sulfate, dihydrogen phosphate, substituted phosphates, phosphonates, acetate, propionate, other longer-chain carboxylates, permanganate, thiocyanate, hydrogen oxalate, hydrogen sulfide, amide and combinations thereof.

23. The method according to any of claims 18 to 22, comprising contacting the

lignocellulose material with an ionic liquid further containing a co-solvent or a mixture of co-solvents, in particular with an aprotic co-solvent or mixture of such co-solvents, preferably a co-solvent which is miscible with the ionic liquid.

24. The method according to claim 22 or 23, wherein the co-solvent is selected from dimethylsulfoxide (DMSO), 1 ,3 dimethyl-2-Imidazolidinone (DMI), l ,3-dimethyl-3, 4,5,6- tetrahydro-2(lH)-pyrimidinone (DMPU), dichloromethane (DCM), Tetrahydrofuran (THF), ethyl acetate, acetone, acetonitrile, dimethylformamide (DMF), hexamethyl- phosphoramide (HMPA), acetone, dioxane, and pyridine, and mixtures thereof, and optionally containing water and other protic solvents, such as alcohols and ammonia, at concentrations below that which causes phase-separation of the ionic liquid.

25. The method according to any of claims 18 to 24, wherein the lignocellulose material or components thereof is solvated in the ionic liquid together with any co-solvent at ambient pressure at a temperature of about 40 °C up to the boiling point of the ionic liquid, of any co-solvent, or of the mixture of the ionic liquid and any co-solvent, preferably at ambient pressure and a temperature of about 75 to 125 °C.

26. The method according to any of claims 18 to 25, wherein the ionic liquid is obtained

- by subjecting a solution according to any of claims 1 to 14 to phase separation by adding a phase separation medium, and optionally by heating or cooling the solution or changing pressure, to form a first phase comprising ionic liquid and a second phase comprising a phase separation medium and any co-solvent;

- recovering the ionic liquid of the first phase;

- optionally combining it with fresh feed; and

- recycling the ionic liquid thus obtained to the contacting with the lignocellulose material.

27. The method according to claim 26, wherein solvated lignocelluloses are separated from the ionic liquid by the addition of a phase separation medium, preferably 0.1 to 50 part by weight, before subjecting the solution to phase separation.

28. The method according to claim 26 or 27, wherein a co-solvent is added to the recycled ionic liquid at the latest when the ionic liquid is contacted with the lignocellulose material.

29. The method according to any of claims 18 to 28, comprising adding 1 to 100 parts by weight of co-solvent to produce a mixture of ionic liquid and co-solvent having a concentration of co-solvent of up to 30 % by mass of the total weight of the ionic liquid and co-solvent.

30. The method according to any of claims 18 to 29, wherein the phase separation medium is selected from the group of polar liquid media, such as water, aqueous solutions, including aqueous solutions of inorganic or organic salts or mixtures thereof, carbon dioxide, optionally in supercritical condition and liquid ammonia, said liquid media optionally being miscible with the ionic liquid.

31. A method of forming a solution of a polymer material comprising contacting in particular 0.1 to 50 parts by weight of the material with in particular 50 to 500 parts by weight of an ionic liquid that comprises anions and cations, said cation being selected from substituted phosphonium ions having Formula II

⁺P[R^! R² R³ R⁴] II wherein

said anions being derived from a Bronsted acid or a mixture of two or more such ions; said ionic liquid being capable of phase separation on mixing with a phase separation medium; said polymer material being selected from the following:

- polysaccharide or materials, not derived from wood, such as chitin or chitosan,

- proteins, in particular keratin, and

- polymers whose properties rely to a degree on H - bonding between polymer chains, such as Kevlar and other aramid polymers, nylons, silk and DNA.

32. A method of recovering at least one lignocellulose component, in particular a polysaccharide or lignin, from a lignocellulose material, comprising the steps of

- forming a solution according to any of claims 1 to 18; and

- adding water or an aqueous solution to the cellulosic or lignocellulosic solution to precipitate dissolved material or part thereof.

33. The method according to claim 32, comprising adding 0.1 to 50 parts by weight, in particular about 1 to 40 parts by weight, of water of an aqueous solution.

34. The method according to claim 32 or 33, wherein the weight ratio of water or the aqueous solution to ionic liquid is about 1 :20 to 20: 1, in particular about 1 : 10 to 10: 1.

35. The method according to any of claims 32 to 34, wherein

- water or aqueous solution are added at a temperature of 15 to 25 °C to separate lignocellulose material from the solution to form precipitate matter; - the precipitated matter is recovered;

- the supernatant is subjected to phase separation by increasing the temperature to a 40 to 100 to °C; and

- optionally the separated phase containing ionic liquid is recovered.

36. Use of a method according to any of claims 32 to 35 for recovering cellulose from solution for the production of paper, paper pulp, cardboard, carboxymethyl cellulose (CMC), biofuel, textiles, fibres, filaments, yearns, foils, films or adhesives .