DE102011083362A1 - Producing cellulose product, hemicellulose product and lignin product, comprises treating lignocellulosic starting material with liquid treatment medium, solubilizing starting material and subjecting for fractional precipitation - Google Patents

Abstract

Producing a cellulose product, a hemicellulose product and a lignin product, comprises treating lignocellulosic starting material with a liquid treatment medium comprising an ionic liquid, solubilizing the starting material at least partially in treatment medium and subjecting the solubilizate for fractional precipitation, which includes at least three precipitation steps.

Description

The present invention relates to a process for the isolation of a cellulose product, a hemicellulose product and a lignin product from a lignocellulose-containing starting material.

With a share of about 700 billion tonnes of the estimated biomass supply of 1.5 billion tonnes on earth, cellulose is the most important member of the group of organic biopolymers and a very versatile raw material. Of particular importance in the future will be the hydrolysis of cellulose to glucose, since in this way, for example, access to large quantities of fermentatively produced bioethanol could be created. In the biomass available as a source of raw materials, however, cellulose hardly ever occurs in pure or sufficiently enriched form, but essentially as a constituent of lignocellulose. The digestion and fractionation of lignocellulose into its main constituents cellulose and lignin as well as possibly further components, such as hemicellulose, are central tasks of a biorefinery concept, which should enable the effective and economical use of this renewable raw material. Here, a growing importance of the biofuel ethanol and glucose as an intermediate in the chemical industry is only conceivable if it succeeds to win this from a different raw material base than from such starchy or sugary plants, which are mainly used for food production.

Vegetable biomass consists of 15 to 35% lignin. This is currently being used mainly for energy purposes. However, lignin is now also of great interest as a raw material in the chemical industry. It is used, for example, for the preparation of low molecular weight aromatic compounds and especially for the preparation of phenolic compounds or vanillin. Lignin / cellulose compositions are used under the name Arboform or liquid wood as plastic from renewable raw materials.

Hemicellulose is another component of lignocellulose. Like cellulose, it is composed of glycosidically linked sugar units, but it is mainly arabinose and xylose. The chains may be more or less branched, and the degree of polymerization is lower than that of the cellulose. Hemicellulose is advantageously suitable as an intermediate for the production of chemicals. It is interesting as well as cellulose as a possible source of fermented ethanol. Furthermore, hemicellulose is used in cosmetics and for the production of chromatography materials. The production of hemicellulose, and in particular high xylan hemicellulose, is a demanding task since it is naturally associated with cellulose and possibly hemicellulose in nature. A process which, in addition to the isolation of cellulose, is also suitable for the isolation of hemicellulose from a lignocellulose-containing starting material is therefore of particular interest.

Various digestion methods for lignocellulose have been developed. M. Galbe and G. Zacchi, in Appl. Microbiol. Biotechnol., 2002, 59, pp. 618-628 , an overview of the production of ethanol from lignocellulosic sources and thus also about methods for the solution of lignocellulose. All known preparation processes contain, as a common step, the hydrolysis of the cellulose and optionally of the hemicellulose to the monomeric sugars. Therefore, the conditions used are harsh and generally unsuitable for the recovery of both longer and shorter chain cellulose.

It is known to use various ionic liquids as non-hydrolyzing solvents for cellulose. So describe Zhu, et al. in Green Chem. 2006, 8, pp. 325-327 in general, the possibility of dissolving cellulose in ionic liquids and recovering it by adding suitable precipitating agents, such as water, ethanol or acetone. Specifically, 1-butyl-3-methylimidazolium chloride ([BMIM] [CI]) and 1-allyl-3-methylimidazolium chloride ([A-MIM] [CI]) are mentioned as suitable ionic liquids.

The CN 1806945 describes a process for pretreatment and enzymolysis of straw. Pretreatment involves treatment with hot water to remove hemicellulose from the straw. The enzymolysis is then carried out in the presence of an ionic liquid.

The WO 2007/101812 describes a process for the degradation of cellulose by dissolution in ionic liquids and treatment at elevated temperatures and optionally with the addition of water.

The WO 2009/071181 describes a process for the production of fuels from biogenic starting materials, such as wood, cellulose, hemicellulose, lignin, etc., in which the starting materials are dissolved in an ionic liquid, subjected to a heterogeneously catalyzed hydrogenation and the reaction product is separated off.

The US 2007/0215300 A1 describes a method of treating a lignocellulosic material with an ionic liquid to remove the lignin contained therein. The ionic liquid can be used in combination with water as cosolvent. To isolate the dissolved lignin this can be precipitated from the liquid phase.

Rinhaldi et al. describe in Angew. Chem. It., Ed. 2008, 47, 8047-8050 a process for the acid-catalyzed depolymerization of cellulose by an Amberlyst 15DRY resin in ionic liquids. This method is also applicable to wood and lignocellulose.

The WO 2008/095252 describes a method for fractionating lignocellulosic material. In the process, the lignocellulosic material is dissolved in an ionic liquid and then precipitated cellulose by the addition of an aqueous base. In the ionic liquid remain lignin and hemicellulose. The lignin is also precipitated by lowering the pH, while the hemicellulose can be separated from the acidified solution by chromatographic techniques.

Sievers et al. describe in Ind. Eng. Chem. Res. 2009, 48, 1277-1286 a process for the acid-catalyzed depolymerization of cellulose and hemicellulose. For this, wood of the frankincense pine in 1-butyl-3-methylimidazoliumchlorid and treated with an acid catalyst.

Liu et al. describe in Chinese Science Bulletin, 2006, 51, 2432-2436 a process for enzymatic hydrolysis of wheat straw and wheat straw treated with steam. Treat the straw with 1-butyl-3-methylimidazolium chloride.

The WO 2008/112291 describes a process for converting lignocellulose to sugar. To remove the lignin, a lignocellulosic material is treated with an ionic liquid and enzymatically hydrolyzes the remaining cellulose and hemicellulose.

The WO 2008/098032 teaches the production of biofuel from lignocellulosic material dissolved in ionic liquids. For this one dissolves wood in ionic liquids and precipitates cellulose by adding a second solvent. The hemicellulose which accumulates in the ionic liquid is likewise separated off by precipitation.

The WO 2007/111605 describes a process for large-scale lignocellulose fractionation. The separation into the lignocellulose constituents cellulose, hemicellulose and lignin takes place by precipitation. As wood solvents, ionic liquids are used in addition to others.

There is still a need for a biorefinery process which makes it possible to use a lignocellulose-containing starting material as completely as possible for the recovery of value products. In addition to the main product cellulose, these valuable substances are mainly lignin as a biogenic source of aromatics and hemicellulose as an independent substance class based on C ₅ sugars.

Surprisingly, it has now been found that the isolation of cellulose, hemicellulose and lignin advantageously succeeds from a lignocellulosic material solubilized in ionic liquids by fractional extraction and precipitation.

The invention relates to a method for producing a cellulose product, a hemicellulose product and a lignin product, which comprises treating a lignocellulose-containing starting material with a liquid treatment medium comprising an ionic liquid, wherein the starting material is at least partially solubilized in the treatment medium and the solubilizate subjected to a fractional precipitation comprising at least three precipitation steps.

• a) ein lignocellulosehaltiges Ausgangsmaterial bereitstellt und mit einem flüssigen Behandlungsmedium behandelt, das eine ionische Flüssigkeit umfasst, wobei das Ausgangsmaterial zumindest teilweise in dem Behandlungsmedium solubilisiert wird,
• b) dem in Schritt a) erhaltenen Solubilisat ein erstes Fällungsmittel (F1) zugibt, wobei eine ligninhaltige flüssige Fraktion und ein erstes Präzipitat erhalten wird, das Cellulose und Hemicellulose enthält,
• c) der in Schritt b) erhaltenen ligninhaltigen flüssigen Fraktion ein zweites Fällungsmittel (F2) zugibt, wobei als zweites Präzipitat das Ligninprodukt erhalten wird,
• d) das in Schritt b) erhaltene erste Präzipitat mit einem flüssigen Waschmedium behandelt, wobei die Hemicellulose zumindest teilweise in dem Waschmedium solubilisiert wird,
• e) das mit Hemicellulose beladene Waschmedium abtrennt, wobei als feste Fraktion das Celluloseprodukt erhalten wird,
• f) dem in Schritt e) erhaltenen, mit Hemicellulose beladenen Waschmedium ein drittes Fällungsmittel (F3) zugibt, wobei als drittes Präzipitat das Hemicelluloseprodukt erhalten wird.

A preferred embodiment is a process for the preparation of a cellulose product, a hemicellulose product and a lignin product, in which

• a) providing a lignocellulosic starting material and treating it with a liquid treatment medium comprising an ionic liquid, wherein the starting material is at least partially solubilized in the treatment medium,
• b) adding to the solubilizate obtained in step a) a first precipitating agent (F1) to obtain a lignin-containing liquid fraction and a first precipitate containing cellulose and hemicellulose,
• c) adding to the lignin-containing liquid fraction obtained in step b) a second precipitant (F2), the lignin product being obtained as the second precipitate,
• d) treating the first precipitate obtained in step b) with a liquid washing medium, wherein the hemicellulose is at least partially solubilized in the washing medium,
• e) separating the washing medium loaded with hemicellulose, the cellulosic product being obtained as a solid fraction,
• f) adding a third precipitating agent (F3) to the hemicellulose-laden washing medium obtained in step e), the hemicellulose product being obtained as the third precipitate.

Lignocellulose forms the structural framework of the plant cell wall and contains as its main components cellulose and lignin as well as hemicelluloses. Other components of the plant cell wall and thus obtained lignocellulose-containing materials are, for. As silicates, extractable low molecular weight organic compounds (so-called extractives such as terpenes, resins, fats), polymers such as proteins, nucleic acids and gum (so-called exudate), etc.

Cellulose is a biopolymer of long chain D-anhydroglucopyranose sugar units linked by β-1,4-glycosidic bonds.

The cellulose product produced by the process according to the invention preferably has a degree of polymerization (DP) of at least 10, more preferably of at least 100. Preferably, the degree of polymerization (DP) of the cellulose is in a range from 200 to 1000, more preferably in a range from 300 to 500 ,

The cellulose product produced by the process according to the invention preferably has a cellulose content of at least 75%, more preferably at least 85%, in particular at least 90%, based on the total weight of the cellulose product. A typical cellulose product according to the invention may contain, based on the total weight of the cellulose product, up to 10% by weight, preferably up to 8% by weight, in particular up to 6% by weight, of lignin. A typical lignin content of the cellulose product according to the invention is in a range of 3 to 6 wt .-%, based on the total weight of the cellulose product. A typical cellulose product according to the invention may contain, based on the total weight of the cellulose product, up to 10% by weight, preferably up to 8% by weight, of ionic liquid. A typical content of ionic liquid of the cellulose product according to the invention is in a range of 3 to 8 wt .-%, based on the total weight of the cellulose product.

Like cellulose, hemicellulose is composed of glycosidically linked sugar units (mainly arabinose and xylose), but the chains are more or less branched and the degree of polymerization is lower than that of cellulose.

The hemicellulose product produced by the process according to the invention preferably has a degree of polymerization (DP) of at most 300, preferably of at most 200. Preferably, the degree of polymerization (DP) of the hemicellulose is in a range from 4 to 150, particularly preferably in a range from 4 to 120. The proof of which repeat units the hemicellulose product according to the invention is constructed (for example the detection of the xylose identity) is carried out by CP-MAS NMR (charge polarized magic angle spinning nuclear magnetic resonance) spectroscopy.

The hemicellulose product produced by the process of the invention preferably has a hemicellulose content of at least 75%, more preferably at least 90%, especially at least 95%, based on the total weight of the hemicellulose product.

The hemicellulose product produced by the process of the invention preferably has a xylene content of at least 75% by weight, more preferably at least 90% by weight, especially at least 95% by weight, based on the total weight of the hemicellulose product.

The repeating units of xylans are predominantly derived from D-xylose. In addition to D-xylose, the xylans may contain other repeating units, preferably derived from D-mannose, D-glucose, D-arabinose, D-galactose, D-galacturonic acid and mixtures thereof. The xylans contained in the hemicellulose product preferably have predominantly (ie, at least 90%) or exclusively β-D-xylopyranose units in the backbone. The linking of the main chain is predominantly (ie at least 90%) or exclusively in β-1,4-glycosidic form. The chains of xylan may be unbranched or have one to two branches per molecule. These branches preferably have exclusively repeat units derived from D-xylose. However, it is also possible that the branches have repeat units that differ from sugars other than D-xylose and / or sugar derivatives. The branches usually consist only of monomeric units, but may also be dimeric or oligomeric.

The hemicellulose product produced by the process according to the invention preferably contains xylans having 1 to 10 repeat units, more preferably 2 to 5 repeat units.

In a specific embodiment, the hemicellulose product prepared by the process according to the invention contains at least 75% by weight of xylans having 1 to 10 repeat units, particularly preferably at least 90% by weight of xylans having 1 to 10 repeat units, in particular at least 95% by weight of xylans with 1 to 10 repeat units, based in each case on the total weight of the hemicellulose product.

In a more specific embodiment, the hemicellulose product produced by the process according to the invention contains at least 75% by weight of xylans having 2 to 5 repeat units, more preferably at least 90% by weight of xylans having 2 to 5 repeat units, especially at least 95% by weight of xylans with 2 to 5 repeat units, based in each case on the total weight of the hemicellulose product.

The number-average molecular weight of the xylans in the hemicellulose product prepared by the process of the invention is preferably in the range of about 500 to 20,000, more preferably 500 to 17,000.

The determination of the molecular weights of the cellulose products and hemicellulose products can be carried out by size exclusion chromatography (SEC). The calibration was carried out with the widely distributed Na-PAA mixture 23250/158/2, whose integral molecular weight distribution curve was determined by SEC laser light scattering, according to the calibration method of MJR Cantow et al. (J. Polym. Sci., A-1, 5, (1967), pp. 1391-1394) but without the suggested concentration correction.

Lignin is a biopolymer whose basic unit is essentially phenylpropane, which, depending on the natural source, may be substituted with one or more methoxy groups on the phenyl rings and with a hydroxy group on the propylene units. Therefore, typical structural units of lignin are p-hydroxyphenylpropane, guaiacylpropane, and syringylpropane linked together by ether bonds and carbon-carbon bonds.

The lignin product produced by the process according to the invention preferably has a lignin content of at least 75%, particularly preferably at least 90%, in particular at least 95%, based on the total weight of the lignin product.

The term "solubilization" in the context of the invention refers to the conversion into a liquid state and in this case comprises the production of solutions of the lignocellulose-containing material as well as the conversion into a different solubilized state. If a lignocellulose-containing material is converted into a solubilized state, the individual polymer molecules need not necessarily be completely surrounded by a solvate shell. It is essential that the polymer changes to a liquid state as a result of the solubilization. Solubilisates in the context of the invention are thus also colloidal solutions, microdispersions, gels, etc. If undissolved components remain in the treatment of the lignocellulose-containing starting material with the liquid medium containing the ionic liquid, this is not critical to the success of the process according to the invention.

Step a)

The present invention can be used lignocellulose-containing starting materials are, for. B. from wood and vegetable fibers available as starting material. Preferred lignocellulosic materials are those of wood and residues of the woodworking industry. These include z. B. the various types of wood, ie hardwoods, such as maple, birch, pear, oak, alder, ash, eucalyptus, hornbeam, cherry, linden, walnut, poplar, willow, etc. and conifers such as Douglas fir, spruce, yew, hemlock, Pine, larch fir, cedar, etc. Suitable are both hardwoods and softwoods. Woody wood cell wall is typically composed of Central European woods as follows: Hardwoods: 42-49% cellulose, hemicellulose 24-30%, lignin 25-30%, extractives 2-9%, ashes (minerals) 0.2-0.8%. Softwoods: cellulose 42-51%, hemicellulose 27-40%, lignin 18-24%, extractives 1-10%, ashes 0.2-0.8%. Wood can be distinguished not only in deciduous and coniferous wood, but also in so-called "hardwoods" and "softwoods", which is not synonymous with the terms deciduous or coniferous wood. Softwood, in contrast to hardwood, means lighter wood (ie wood with a density of less than 0.55 g / cm ³ , for example willow, poplar, Linden and almost all conifers). In principle, all hardwoods and all softwoods are suitable for use in the process according to the invention. The wood used in the process according to the invention can also be used in ready-made form, for. In the form of pellets. Suitable residues in the woodworking industry are in addition to wood waste and sawdust, parquet sanding dust, etc.

Preferred lignocellulose-containing starting materials are furthermore natural fiber materials, which are preferably selected from flax, hemp, sisal, jute, straw, coconut fibers, switchgrass (Panicum virgatum) and other natural fibers other than these. Suitable lignocellulosic starting materials also fall as a residue in agriculture, z. B. in the harvest of grain (wheat straw, corn straw, etc.), corn, sugar cane (bagasse), etc. Suitable lignocellulose-containing starting materials also fall as a residue in forestry, z. B. in the form of branches, barks, wood chips, etc. A good source of lignocellulose-containing starting materials are short rotation crops (short rotation crops), which allow a high biomass production in a relatively small area.

In the context of the present application, ionic liquids refer to organic salts which are already liquid at temperatures below 180 ° C. Preferably, the ionic liquids have a melting point of less than 150 ° C, more preferably less than 120 ° C, especially less than 100 ° C.

Ionic liquids, which are already in a liquid state at room temperature, are used, for example, by KN Marsh et al., Fluid Phase Equilibria 219 (2004), 93-98 and JG Huddleston et al., Green Chemistry 2001, 3, 156-164 described.

For use in the process according to the invention suitable ionic liquids are in the WO 2008/090155 and WO 2008/090156 which is incorporated herein by reference.

Cations and anions are present in the ionic liquid. In this case, within the ionic liquid from the cation, a proton or an alkyl radical can be transferred to the anion, resulting in two neutral molecules. In the ionic liquid used according to the invention, therefore, there can be an equilibrium of anions, cations and neutral molecules formed therefrom.

Preferred ionic liquids are

(A) Salts of the general formula (I) [A] + / n [Y] ^n- (I), where n is 1, 2, 3 or 4, [A] ^{+ is} a quaternary ammonium cation, an oxonium cation, a sulfonium cation or a phosphonium cation and [Y] ^{n- is} a polyatomic, mono- , di-, tri- or tetravalent anion or mixtures of these anions;

(B) mixed salts of the general formulas (II) [A ¹ ] ⁺ [A ² ] ⁺ [Y] ^n- (II.a), where n = 2, [A ¹ ] ⁺ [A ² ] ⁺ [A ³ ] ⁺ [Y] ^n- (II.b), where n = 3, [A ¹ ] ⁺ [A ² ] ⁺ [A3] ⁺ [A ⁴ ] ⁺ [Y] ⁿ - (II.c), where n = 4, and where [A ¹ ] ⁺ , [A ² ] ⁺ , [A ³ ] ⁺ and [A ⁴ ] ^{+ are selected} independently of one another from the groups mentioned for [A] ⁺ and [Y] ^{n -} the meaning mentioned under (A) has; or

(C) mixed salts of the general formulas (III) [A ¹ ] ⁺ [A ² ] ⁺ [A ³ ] ⁺ [M ¹ ] ⁺ [Y] ^n- (III.a), where n = 4, [A ¹ ] ⁺ [A ² ] ⁺ [M ¹ ] ⁺ [M ² ] ⁺ [Y] ^n- (III.b), where n = 4, [A ¹ ] ⁺ [M ¹ ] ⁺ [M ² ] ⁺ [M ³ ] ⁺ [Y] ^n- (III.c), where n = 4, [A ¹ ] ⁺ [A ² ] ⁺ [M ¹ ] ⁺ [Y] ^n- (III.d), where n = 3, [A ¹ ] ⁺ [M ¹ ] ⁺ [M ² ] ⁺ [Y] ^n- (III.e), where n = 3, [A ¹ ] ⁺ [M ¹ ] ⁺ [Y] ^n- (III.f), where n = 2, [A ¹ ] ⁺ [A ² ] ⁺ [M ⁴ ] ²⁺ [Y] ^n- (III.g), where n = 4, [A ¹ ] ⁺ [M ¹ ] ⁺ [M ⁴ ] ²⁺ [Y] ^n- (III.h), where n = 4, [A ¹ ] ⁺ [M ⁵ ] ³⁺ [Y] ^n- (III.i), where n = 4, [A ¹ ] ⁺ [M ⁴ ] ²⁺ [Y] ^n- (III.j), where n = 3, and wherein [A ¹ ] ⁺ , [A ² ] ⁺ and [A ³ ] ^{+ are} independently selected from the groups mentioned for [A] ⁺ , [Y] ^{n- has} the meaning given under (A) and [M ¹ ] ⁺ , [M ² ] ⁺ , [M ³ ] ⁺ monovalent metal cations, [M ⁴ ] ²⁺ divalent metal cations and [M ⁵ ] ³⁺ trivalent metal cations.

Preferred are salts of groups A and B, more preferably of group A.

The metal cations [M ¹ ] ⁺ , [M ² ] ⁺ , [M ³ ] ⁺ [M ⁴ ] ²⁺ and [M ⁵ ] ³⁺ mentioned in formulas (III.a) to (III.j) are are generally metal cations of the 1st, 2nd, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 13th and 14th group of the periodic table. Suitable metal cations are, for example, Li ^+, Na ^+, K ^+, Cs ^+, Mg ^2+, Ca ^2+, Ba ^2+, Cr ^3+, Fe ^2+, Fe ^3+, CO ^2+, Ni ^2+, Cu ^{2 +} , Ag ⁺ , Zn ²⁺ and Al ³⁺ .

Suitable compounds which are suitable for forming the cation [A] ⁺ of ionic liquids are, for. B. in the DE 102 02 838 A1 described. These compounds preferably contain at least one heteroatom, such as. B. 1 to 10 heteroatoms, which are preferably selected from nitrogen, oxygen, phosphorus and sulfur atoms. Preference is given to compounds which contain at least one nitrogen atom and, if appropriate, additionally at least one further heteroatom other than nitrogen. Preference is given to compounds which contain at least one nitrogen atom, particularly preferably 1 to 10 nitrogen atoms, in particular 1 to 5 nitrogen atoms, very particularly preferably 1 to 3 nitrogen atoms and especially 1 or 2 nitrogen atoms. The latter nitrogen compounds may contain other heteroatoms such as oxygen, sulfur or phosphorus atoms.

The nitrogen atom is z. B. a suitable carrier of the positive charge in the cation of the ionic liquid. In the event that the nitrogen atom is the carrier of the positive charge in the cation of the ionic liquid, in the synthesis of the ionic liquids, a cation can first be generated by quaternization on the nitrogen atom of, for example, an amine or nitrogen heterocycle. The quaternization can be carried out by protonation of the nitrogen atom. Depending on the protonation reagent used, salts with different anions are obtained. In cases where it is not possible to form the desired anion already during the quaternization, this can be done in a further synthesis step. Starting from, for example, an ammonium halide, the halide can be reacted with a Lewis acid to form a complex anion from halide and Lewis acid. Alternatively, replacement of a halide ion with the desired anion is possible. This can be done by adding a metal salt to precipitate the metal halide formed, via an ion exchanger, or by displacing the halide ion with a strong acid (to release the hydrohalic acid). Suitable methods are, for example, in Angew. Chem. 2000, 112, pp. 3926-3945 and the literature cited therein.

Preference is given to those compounds which contain at least one five- to six-membered heterocycle, in particular a five-membered heterocycle, which has at least one nitrogen atom and optionally an oxygen or sulfur atom, particular preference is given to those compounds which contain at least one five- to six-membered heterocycle, which has one, two or three nitrogen atoms and one sulfur or one oxygen atom, very particularly preferably those with two nitrogen atoms. Further preferred are aromatic heterocycles.

Particularly preferred compounds are those which have a molar mass of less than 1000 g / mol, very particularly preferably less than 800 g / mol and in particular less than 500 g / mol.

Preferred as cations are pyridinium ions. These are in particular selected from pyridinium, 2-methylpyridinium, 2-ethylpyridinium, 5-ethyl-2-methylpyridinium and 2-methyl-3-ethylpyridinium and also 1-methylpyridinium, 1-ethylpyridinium, 1- (1-butyl) pyridinium, 1 (1-Hexyl) pyridinium, 1- (1-octyl) -pyridinium, 1- (1-hexyl) -pyridinium, 1- (1-octyl) -pyridinium, 1- (1-dodecyl) -pyridinium, 1- ( 1-tetradecyl) -pyridinium, 1- (1-hexadecyl) -pyridinium, 1,2-dimethylpyridinium, 1-ethyl-2-methylpyridinium, 1- (1-butyl) -2-methylpyridinium, 1- (1-hexyl) 2-methylpyridinium, 1- (1-octyl) -2-methylpyridinium, 1- (1-dodecyl) -2-methylpyridinium, 1- (1-tetradecyl) -2-methylpyridinium, 1- (1-hexadecyl) -2 -methylpyridinium, 1-methyl-2-ethylpyridinium, 1,2-diethylpyridinium, 1- (1-butyl) -2-ethylpyridinium, 1- (1-hexyl) -2-ethylpyridinium, 1- (1-octyl) -2 -ethylpyridinium, 1- (1-dodecyl) -2-ethylpyridinium, 9- (1-tetradecyl) -2-ethylpyridinium, 1- (1-hexadecyl) -2-ethylpyridinium, 1,2-dimethyl-5-ethylpyridinium , 1,5-diethyl-2-methyl-pyridinium, 1- (1-butyl) -2-methyl-3-ethyl-pyrid inium, 1- (1-hexyl) -2-methyl-3-ethylpyridinium and 1- (1-octyl) -2-methyl-3-ethyl-pyridinium, 1- (1-dodecyl) -2-methyl- 3-ethyl-pyridinium, 1- (1-tetradecyl) -2-methyl-3-ethyl-pyridinium and 1- (1-hexadecyl) -2-methyl-3-ethyl-pyridinium.

Also preferred as cations are unsubstituted or substituted pyridazinium ions.

Also preferred as cations are unsubstituted or substituted pyrimidinium ions.

Also preferred as cations are unsubstituted or substituted pyrazinium ions.

Also preferred as cations are unsubstituted or substituted imidazolium ions. Particularly suitable imidazolium ions are 1-methylimidazolium, 1-ethylimidazolium, 1- (1-propyl) -imidazolium, 1- (1-allyl) -imidazolium, 1- (1-butyl) -imidazolium, 1- (1-octyl) - imidazolium, 1- (1-dodecyl) imidazolium, 1- (1-tetradecyl) imidazolium, 1- (1-hexadecyl) imidazolium, 1,3-dimethyl imidazolium, 1,3-diethyl imidazolium, 1-ethyl-3 methylimidazolium, 1- (1-butyl) -3-methylimidazolium, 1- (1-butyl) -3-ethylimidazolium, 1- (1-hexyl) -3-methylimidazolium, 1- (1-hexyl) -3- ethylimidazolium, 1- (1-hexyl) -3-butylimidazolium, 1- (1-octyl) -3-methylimidazolium, 1- (1-octyl) -3-ethylimidazolium, 1- (1-octyl) -3- butylimidazolium, 1- (1-dodecyl) -3-methylimidazolium, 1- (1-dodecyl) -3-ethylimidazolium, 1- (1-dodecyl) -3-butylimidazolium, 1- (1-dodecyl) -3-octylimidazolium, 1- (1-Tetradecyl) -3-methylimidazolium, 1- (1-Tetradecyl) -3-ethylimidazolium, 1- (1-Tetradecyl) -3-butylimidazolium, 1- (1-Tetradecyl) -3-octylimidazolium, 1- (1-hexadecyl) -3-methylimidazolium, 1- (1-hexadecyl) -3-ethylimidazolium, 1- (1-hexadecyl) -3-butylimidazole 1- (1-hexadecyl) -3-octylimidazolium, 1,2-dimethylimidazolium, 1,2,3-trimethylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1- (1-butyl) -2,3- dimethylimidazolium, 1- (1-hexyl) -2,3-dimethylimidazolium, 1- (1-octyl) -2,3-dimethylimidazolium, 1,4-dimethylimidazolium, 1,3,4-trimethylimidazolium, 1,4- Dimethyl 3-ethylimidazolium, 3-methylimidazolium, 3-ethylimidazolium, 3-n-propylimidazolium, 3-n-butylimidazolium, 1,4-dimethyl-3-octylimidazolium, 1,4,5-trimethylimidazolium, 1,3,4, 5-tetramethylimidazolium, 1,4,5-trimethyl-3-ethylimidazolium, 1,4,5-trimethyl-3-butylimidazolium, 1,4,5-trimethyl-3-octylimidazolium, 1-prop-1-ene-3 yl-3-methylimidazolium and 1-prop-1-en-3-yl-3-butylimidazolium. Especially suitable imidazolium ions (IVe) are 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1- (n-butyl) -3-methylimidazolium.

Also preferred as cations are unsubstituted or substituted pyrazolium ions. Particularly preferred pyrazolium ions are pyrazolium and 1,4-dimethylpyrazolium.

Also preferred as cations are unsubstituted or substituted pyrazolinium ions.

Also preferred as cations are unsubstituted or substituted imidazolinium ions.

Also preferred as cations are unsubstituted or substituted thiazolium ions.

Also preferred as cations are unsubstituted or substituted 1,2,4-triazolium ions.

Also preferred as cations are unsubstituted or substituted pyrrolidinium ions.

Also preferred as cations are unsubstituted or substituted imidazolidinium ions.

Also preferred as cations are unsubstituted or substituted ammonium ions. Examples of the tertiary amines from which the quaternary ammonium ions are derived by quaternization with the radical R mentioned are diethyl-n-butylamine, diethyl-tert-butylamine, diethyl-n-pentylamine, diethylhexylamine, diethyloctylamine, diethyl (2-ethylhexyl ) -amine, di-n-propylbutylamine, di-n-propyl-n-pentylamine, di-n-propylhexylamine, di-n-propyloctylamine, di-n-propyl- (2-ethylhexyl) -amine, di-isopropylethylamine, Di-isopropyl-n-propylamine, di-isopropyl-butylamine, diisopropylpentylamine, di-isopropylhexylamine, di-isopropyloctylamine, di-isopropyl- (2-ethylhexyl) -amine, di-n-butylethylamine, di-n-butyl n-propylamine, di-n-butyl-n-pentylamine, di-n-butylhexylamine, Di-n-butyloctylamine, di-n-butyl- (2-ethylhexyl) -amine, Nn-butylpyrrolidine, N-sec-butylpyrrodidine, N-tert-butylpyrrolidine, Nn-pentylpyrrolidine, N, N-dimethylcyclohexylamine, N, N- Diethylcyclohexylamine, N, N-di-n-butylcyclohexylamine, Nn-propylpiperidine, N-isopropylpiperidine, Nn-butylpiperidine, N-sec-butylpiperidine, N-tert-butylpiperidine, Nn-pentylpiperidine, Nn-butylmorpholine, N-sec- Butylmorpholine, N-tert-butylmorpholine, Nn-pentylmorpholine, N-benzyl-N-ethylaniline, N-benzyl-Nn-propylaniline, N-benzyl-N-isopropyl-niline, N-benzyl-Nn-butylaniline, N, N- Dimethyl-p-toluidine, N, N-diethyl-p-toluidine, N, N-di-n-butyl-p-toluidine, diethylbenzylamine, di-n-propylbenzylamine, di-n-butylbenzylamine, diethylphenylamine, di-n- Propylphenylamine and di-n-butylphenylamine. Preferred tertiary amines are di-isopropylethylamine, diethyl-tert-butylamine, di-iso-propylbutylamine, di-n-butyl-n-pentylamine, N, N-di-n-butylcyclohexylamine and tertiary amines of pentyl isomers. Particularly preferred tertiary amines are di-n-butyl-n-pentylamine and tertiary amines of pentyl isomers. Another preferred tertiary amine having three identical residues is triallylamine.

Also preferred as cations are unsubstituted or substituted guanidinium ions. A most preferred guanidinium ion is N, N, N ', N', N ", N" -hexamethylguanidinium.

Also preferred as cations are unsubstituted or substituted cholinium ions.

Also preferred as cations are unsubstituted or substituted cations of 1,5-diazabicyclo [4.3.0] non-5-ene (DBN) and 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU).

Also preferred as cations are unsubstituted or substituted phosphonium ions.

Also preferred as cations are unsubstituted or substituted sulfonium ions.

Among the above-mentioned heterocyclic cations, imidazolium ions, imidazolinium ions, pyridinium ions, pyrazolinium ions and pyrazolium ions are preferable. Particularly preferred are the imidazolium ions and cations of DBU and DBN.

As anions, in principle, all anions can be used. In a specific embodiment, the ionic liquid used in the process according to the invention exclusively comprises polyatomic anions. Then, in principle, all polyatomic, d. H. polyatomic anions (anions with two or more than two atoms), can be used. The use of polyatomic anions eliminates the corrosion problems associated with the use of monatomic anions, especially CI. This is particularly advantageous in the reactor design.

• 1.) der Gruppe der Halogenide, Pseudohalogenide und halogenhaltigen Verbindungen,
• 2.) der Gruppe der Sulfate, Sulfite und Sulfonate,
• 3.) der Gruppe der Phosphate,
• 4.) der Gruppe der Phosphonate und Phosphinate,
• 5.) der Gruppe der Phosphite,
• 6.) der Gruppe der Phosphonite und Phosphinite,
• 7.) der Gruppe der Carbonsäuren,
• 8.) der Gruppe der Anionen von Hydroxycarbonsäuren und Zuckersäuren,
• 9.) der Gruppe der Saccharinate (Salze des o-Benzoesäuresulfimids),
• 10.) der Gruppe der Borgte,
• 11.) der Gruppe der Boronate,
• 12.) der Gruppe der Carbonate und Kohlensäureester,
• 13.) der Gruppe der Silikate und Kieselsäuresäureester,
• 14.) der Gruppe der Alkyl- bzw. Arylsilanolate,
• 15.) der Gruppe der Carbonsäureimide, Bis(sulfonyl)imide und Sulfonylimide,
• 16.) der Gruppe der Methide,
• 17.) der Gruppe der Alkoxide und Aryloxide,
• 18.) der Gruppe der Hydrogensulfide, Polysulfide, Hydrogenpolysulfide und Thiolate.

The anion of the ionic liquid is for example selected from

• 1.) the group of halides, pseudohalides and halogen-containing compounds,
• 2.) the group of sulfates, sulfites and sulfonates,
• 3.) the group of phosphates,
• 4.) the group of phosphonates and phosphinates,
• 5.) the group of phosphites,
• 6.) the group of phosphonites and phosphinites,
• 7.) the group of carboxylic acids,
• 8.) the group of the anions of hydroxycarboxylic acids and sugar acids,
• 9.) the group of saccharinates (salts of o-benzoic acid sulfimide),
• 10.) the group of borrowers,
• 11.) the group of boronates,
• 12.) the group of carbonates and carbonic esters,
• 13.) the group of silicates and silicic acid esters,
• 14.) the group of alkyl or aryl silanolates,
• 15.) the group of carboximides, bis (sulfonyl) imides and sulfonylimides,
• 16.) the group of methides,
• 17.) the group of alkoxides and aryloxides,
• 18.) the group of hydrogen sulfides, polysulfides, Hydrogenpolysulfide and thiolates.

To group 1) include z. B. anions of the formulas: F ^-, Cl ^-, Br ^-, I ^-, BF ₄ ^-, PF ₆ ^-, CF ₃ SO ₃ ^-, (CF ₃ SO _{3) 2} N ^-, CF ₃ CO ₂ ^-, CCl ₃ CO ₂ ^-, CN ^-, SCN ^-, OCN ^-.

To group 2) include z. B. Anions of the formulas: SO ₄ ^2- , HSO ₄ ^- , SO ₃ ^2- , HSO ₃ ^- , R ^c OSO ₃ ^- , R ^c SO ₃ ^- .

To group 3) include z. B. Anions of the formulas: PO ₄ ^3- , HPO ₄ ^2- , H ₂ PO ₄ ^- , R ^c PO ₄ ^2- , HR ^c PO ₄ ^- , R ^c R ^d PO ₄ ^- .

To group 4) include z. B. Anions of the formulas: R ^c HPO ₃ ^- , R ^c R ^d PO ₂ ^- , R ^c R ^d PO ₃ ^- .

To group 5) include z. B. Anions of the formulas: PO ₃ ^3- , HPO ₃ ^2- , H ₂ PO ₃ ^- , R ^c PO ₃ ^2- , R ^c HPO ₃ ^- , R ^c R ^d PO ₃ ^- .

To group 6) include z. B. Anions of the formulas: R ^c R ^d PO ₂ ^- , R ^c HPO ₂ -, R ^c R ^d PO ^- , R ^c HPO ^- .

To group 7) include z. B. anions of the formula R ^c COO ^- .

To group 10) include z. B. Anions of the formulas: BO ^{3 3-} , HBO ₃ ^2- , H ₂ BO ₃ ^- , R ^c R ^d BO ₃ ^- , R ^c HBO ₃ ^- , R ^c BO ₃ ^2- , B (OR ^c ) (OR ^d ) (OR ^d ) (OR ^e ) ^- , B (HSO ₄ ) ₄ ^- , B (R ^c SO ₄ ) ₄ ^- .

To group 11) include z. B. Anions of the formulas: R ^c BO ₂ ^2- , R ^c R ^d BO ^- .

To group 12) include z. B. Anions of the formulas: HCO ₃ ^- , CO ₃ ^2- , R ^c CO ₃ ^- .

To group 13) include z. B. anions of the formulas: SiO ₄ ^4- , HSiO ₄ ^3- , H ₂ SiO ₄ ^2- , H ₃ SiO ₄ ^- , R ^c SiO ₄ ^3- , R ^c R ^d SiO ₄ ^2- , R ^c R ^d R ^e SiO ₄ ^-, HR ^c SiO ₄ ^2-, H ₂ R ^c SiO ₄ ^-, HR ^c R ^d SiO ₄ ^-.

To group 14) include z. B. anions of the formulas: R ^c SiO ₃ ^3-, R ^c R ^d SiO ₂ ^2-, R ^c R ^d R ^e SiO ^-, R ^c R ^d R ^e SiO ₃ ^-, R ^c R ^d R ^e SiO ₂ ^- , R ^c R ^d SiO ₃ ^2- .

To group 15) include z. B. Anions of the formulas:

To group 16) include z. B. Anions of the formulas:

To group 17) include z. B. anions of the formula R ^c O ^- .

To group 18) include z. B. Anions of the formulas HS ^- , [S _c ] ^2- , [HS _v ] ^- , [R ^c S] ^- , where v is a whole positive number from 2 to 10.

• – Wasserstoff;
• – unsubstituiertes oder substituiertes Alkyl, vorzugsweise unsubstituiertes oder substituiertes C₁-C₃₀-Alkyl, besonders bevorzugt unsubstituiertes oder substituiertes C₁-C₁₈-Alkyl, das durch wenigstens ein Heteroatom oder heteroatomhaltige Gruppe unterbrochen sein kann;
• – unsubstituiertes oder substituiertes Aryl, vorzugsweise unsubstituiertes oder substituiertes C₆-C₁₄-Aryl, besonders bevorzugt unsubstituiertes oder substituiertes C₆-C₁₀-Aryl;
• – unsubstituiertes oder substituiertes Cycloalkyl, vorzugsweise unsubstituiertes oder substituiertes C₅-C₁₂-Cycloalkyl;
• – unsubstituiertes oder substituiertes Heterocycloalkyl, vorzugsweise unsubstituiertes oder substituiertes Heterocycloalkyl mit 5 oder 6 Ringatomen, wobei der Ring neben Kohlenstoffringatomen 1, 2 oder 3 Heteroatome oder heteroatomhaltige Gruppen aufweist;
• – unsubstituiertes oder substituiertes Heteroaryl, vorzugsweise unsubstituiertes oder substituiertes Heteroaryl mit 5 bis 10 Ringatomen, wobei der Ring neben Kohlenstoffringatomen 1, 2 oder 3 Heteroatome oder heteroatomhaltige Gruppen aufweist, die ausgewählt sind unter Sauerstoff, Stickstoff, Schwefel und NR^a; wobei in Anionen, die mehrere Reste R^c bis R^f aufweisen, auch jeweils zwei dieser Reste zusammen mit dem Teil des Anions, an das sie gebunden sind, für wenigstens einen gesättigten, ungesättigten oder aromatischen Ring oder ein Ringsystem mit 1 bis 12 Kohlenstoffatomen stehen können, wobei der Ring oder das Ringsystem 1 bis 5 nicht benachbarte Heteroatome oder heteroatomhaltige Gruppen aufweisen kann, die vorzugsweise ausgewählt sind unter Sauerstoff, Stickstoff, Schwefel und NR^a, und wobei der Ring oder das Ringsystem unsubstituiert ist oder substituierten sein kann.

The radical R ^c, R ^d, R ^e and R ^f are each independently preferably

• - hydrogen;
• Unsubstituted or substituted alkyl, preferably unsubstituted or substituted C ₁ -C ₃₀ -alkyl, more preferably unsubstituted or substituted C ₁ -C ₁₈ -alkyl which may be interrupted by at least one heteroatom or heteroatom-containing group;
• Unsubstituted or substituted aryl, preferably unsubstituted or substituted C ₆ -C ₁₄ -aryl, more preferably unsubstituted or substituted C ₆ -C ₁₀ -aryl;
• Unsubstituted or substituted cycloalkyl, preferably unsubstituted or substituted C ₅ -C ₁₂ cycloalkyl;
• Unsubstituted or substituted heterocycloalkyl, preferably unsubstituted or substituted heterocycloalkyl having 5 or 6 ring atoms, the ring having, in addition to carbon ring atoms, 1, 2 or 3 heteroatoms or heteroatom-containing groups;
• Unsubstituted or substituted heteroaryl, preferably unsubstituted or substituted heteroaryl having 5 to 10 ring atoms, the ring having in addition to carbon ring atoms 1, 2 or 3 heteroatoms or heteroatom-containing groups selected from oxygen, nitrogen, sulfur and NR ^a ; wherein in anions which have a plurality of radicals R ^c to R ^f , in each case two of these radicals together with the part of the anion to which they are attached represent at least one saturated, unsaturated or aromatic ring or a ring system having 1 to 12 carbon atoms may be wherein the ring or the ring system may have 1 to 5 non-adjacent heteroatoms or heteroatom-containing groups, which are preferably selected from oxygen, nitrogen, sulfur and NR ^a , and wherein the ring or the ring system is unsubstituted or may be substituted.

Preferably, the anions are not halide (ie not for F ^-, Cl ^-, Br ^-, I ^-).

Preferred anions are selected, for example, from the group of pseudohalides and halogen-containing compounds, the group of carboxylic acids, the group of sulfates, sulfites and sulfonates and the group of phosphates.

Preferred anions are formate, acetate, propionate, butyrate, lactate, saccharinate, carbonate, bicarbonate, sulfate, sulfite, C ₁ -C ₄ alkyl sulfates, methanesulfonate, tosylate, trifluoroacetate, C ₁ -C ₄ dialkyl phosphates and hydrogen sulfate.

Particularly preferred anions are HCOO ^- , CH ₃ COO ^- , CH ₃ CH ² COO ^- , carbonate, bicarbonate, sulfate, sulfite, tosylate, CH ₃ SO ₃ ^- or CH ₃ OSO ₃ ^- .

Suitable ionic liquids for use in the process according to the invention are commercially available, for. B. under the brand name Basionic ^® BASF SE.

Advantageous for use in the method according to the invention are, for. B .:
1-ethyl-3-methylimidazolium methanesulfonate (EMIM CH ₃ SO ₃ , Basionic ST 35),
1-butyl-3-methylimidazolium methanesulfonate (BMIM CH ₃ SO ₃ , Basionic ST 78), methylimidazolium hydrogen sulfate (HMIM HSO ₄ Basionic AC 39),
1-ethyl-3-methylimidazolium hydrogen sulfate (EMIM HSO ₄ Basionic AC 25),
1-Butyl-3-methylimidazolium hydrogen sulfate (BMIM HSO4 Basionic AC 28)
1-ethyl-3-methylimidazolium acetate (EMIM acetate, Basionic BC 01),
1-butyl-3-methylimidazolium acetate (BMIM acetate, Basionic BC 02).

Particularly preferred are 1-ethyl-3-methylimidazolium acetate, 1,3-diethylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, and mixtures thereof. Especially suitable is 1-ethyl-3-methylimidazolium acetate.

In a specific embodiment, the lignocellulosic starting material is subjected to at least one pre-treatment step before or during the treatment with the ionic liquid. This includes z. As a mechanical comminution of cellulose-containing starting material, eg. B. by grinding and / or shredding. In a special embodiment, the mechanical comminution takes place in the presence of the ionic liquid. It is advantageous to comminute the lignocellulosic material to particles having an average size of at most 1 cm, preferably of at most 5 mm, in particular of at most 1 mm. Optionally, further comminution can be carried out on particles having an average size of at most 100 μm. Due to their material properties, fiber-containing materials (such as flax, hemp, sisal, jute, straw, coconut fibers, switchgrass, etc.) are preferably subjected not to a pressure-shear comminution but to an impact comminution. Suitable grinding devices are hammer mills, grinders operating on the principle of jet milling and beater wheel mills. The latter are especially suitable for high throughputs.

• – gegebenenfalls Abtrennung von Feststoffen, wie Sand und Steinen mittels Schwerteilausleser und Siebung,
• – gegebenenfalls Vorzerkleinerung
• – Zerkleinerung in einer Prallmühle, vorzugsweise in einer Schlagradmühle,
• – Abtrennung des Mahlgutes.

A suitable method for comminuting fibrous materials (such as flax, hemp, sisal, jute, straw, coconut fiber, switchgrass, etc.) comprises the following steps:

• - if necessary, separation of solids such as sand and stones by means of heavy particle screening and sieving,
• - optionally pre-crushing
• Crushing in an impact mill, preferably in a beater mill,
• - Separation of the ground material.

• – gegebenenfalls Vorzerkleinerung der Baumstämme (zweistufig)
• – Zerkleinerung in einer Prallmühle, vorzugsweise in einer Schlagradmühle,
• – Abtrennung des Mahlgutes.

The grinding of wood is very similar to that of straw. A suitable method of comminuting wood involves the following steps:

• - optionally pre-shredding the tree trunks (two-stage)
• Crushing in an impact mill, preferably in a beater mill,
• - Separation of the ground material.

Suitable liquid treatment media for the treatment of the lignocellulose-containing starting material in step a) of the method according to the invention comprise at least one ionic liquid, as defined above.

The treatment of the lignocellulose-containing starting material with a liquid treatment medium which comprises an ionic liquid is generally carried out by bringing the lignocellulose-containing starting material into intimate contact with the treatment medium. In this case, the lignocellulose-containing starting material is preferably substantially completely solubilized in the treatment medium containing the ionic liquid. It is advantageously not necessary to subject the solubilized lignocellulosic material to a cleaning step to remove insoluble matter. For solubilization, the lignocellulosic material and the ionic liquid can be intimately contacted with each other by usual methods. For this purpose, the usual mixing devices, such as stirred tank and stirred tank, the aforementioned mechanical crushing devices, etc. are suitable.

Preferably, the treatment of the lignocellulose-containing starting material in step a) at a temperature of at most 200 ° C, more preferably at most 150 ° C and in particular at most 120 ° C. The treatment is preferably carried out at a temperature of at least 20 ° C, more preferably at least 40 ° C. The heating can be indirect or direct, preferably indirect. The indirect heating can be done with customary devices such. B. by heat exchangers, heat baths or microwave irradiation. For direct heating, a hot, compatible with the ionic liquid used heat transfer fluid can be used.

The pressure in the treatment of the lignocellulose-containing starting material in step a) is generally in a range from 0.1 bar to 100 bar, preferably 1 bar to 10 bar. In a special version, working at ambient pressure.

The duration of treatment of the lignocellulose-containing starting material in step a) is generally 0.5 minutes to 7 days, preferably 5 minutes to 96 hours.

Advantageously, the process according to the invention makes it possible to treat the lignocellulose-containing starting material with an ionic liquid which contains additional liquid components in an amount in which no precipitation of solubilized lignocellulose constituents from the treatment medium takes place. Additional liquid components are the precipitants and washing media described in more detail below. Water can be z. B. originate from the cellulosic starting material or already contained in the ionic liquid.

The water content of the liquid treatment medium used in step a) is preferably 0.05 to 15 wt .-%, particularly preferably 0.1 to 10 wt .-%, based on the weight of the total treatment liquid (ionic liquid, water and optionally further below the treatment conditions liquid components). It is of course also possible to work at lower water contents than 0.05 wt .-%, since the lower limit of the water content for the basic implementation of the method is not critical, while at high water contents, the precipitation of the cellulose occurs. The water can come from both the ionic liquid used and from the cellulose material used.

The liquid treatment medium used in step a) may contain at least one organic solvent. The organic solvent may be contained instead of or in addition to water. Suitable organic solvents are those described below as precipitant (F1). Preference is given to using C ₁ -C ₄ -alcohols, in particular methanol. The content of the treatment agent to organic solvents is preferably at most 15 wt .-%, more preferably at most 10 wt .-%, in particular at most 5 wt .-%, based on the total weight of the liquid treatment medium. In a specific embodiment, a liquid treatment medium containing 0.1 to 5% by weight of methanol, based on the total weight of the liquid treatment medium, is used to treat the lignocellulose-containing starting material in step a).

In the treatment of the lignocellulose-containing starting material in step a) with the treatment medium comprising at least one ionic liquid, a solubilisate (a liquid phase) containing cellulose, hemicellulose and lignin in dissolved form is generally obtained.

Step b)

According to the invention, a first precipitant (F1) is added to the solubilizate from step a) in step b), a lignin-containing liquid fraction and a first precipitate being obtained. The first precipitate is depleted of lignin and contains cellulose and hemicellulose.

The first precipitant (F1) is preferably selected from organic solvents or solvent mixtures which are at least partially miscible with the ionic liquid used for the treatment of the lignocellulosic material in step a). Particularly preferably, the first precipitant (F1) is completely miscible with the ionic liquid.

In step b), preference is given to using as precipitant (F1) a solvent or solvent mixture which, in combination with the ionic liquid, is capable of dissolving lignin.

The first precipitant (F1) is preferably a solvent or solvent mixture which is selected from water, alcohols, diols and polyols, aminoalcohols, aromatic solvents, halogenated solvents, aliphatic hydrocarbons, ethers, ketones, esters, formamide, dimethylformamide (DMF). , Dimethylacetamide, dimethyl sulfoxide (DMSO), acetonitrile and mixtures thereof.

The first precipitant (F1) is preferably selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, ethanediol, propanediol, glycol, ethanolamine, diethanolamine, triethanolamine, benzene, toluene, ethylbenzene, xylenes, dichloromethane , Chloroform, carbon tetrachloride, dichloroethane, chlorobenzene, pentane, hexane, heptane, octane, ligroin, petroleum ether, cyclohexane, decalin, tetrahydrofuran, diethyl ether, methyl tert-butyl ether, diethylene glycol monomethyl ether, acetone, methyl ethyl ketone, ethyl acetate, formamide, dimethylformamide (DMF). , Dimethylacetamide, dimethyl sulfoxide (DMSO), acetonitrile and mixtures thereof.

Particular preference is given to using at least one alcohol as first precipitant (F1). These include in particular methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol and mixtures thereof. Particular preference is given to using ethanol as the first precipitating agent (F1).

The first precipitant (F1) may additionally contain ionic liquids. This may be the case, for example, if it is reused precipitant from the process of the invention. The proportion of ionic liquid in the precipitant (F1) is generally at most 50 wt .-%, more preferably at most 25%, based on the total weight of the first precipitant (F1). Such a content of ionic liquids is not critical to the success of cellulose and hemicellulose precipitation.

The separation of lignin-containing fraction and cellulose and hemicellulose-containing precipitate can be carried out by conventional separation methods, such as filtration, centrifugation or a combination thereof. For the purpose of acceleration, the filtration can be carried out under pressure which is increased on the inlet side or reduced on the outlet side. Usual filtration methods are z. B. cake and depth filtration (eg., Described in A. Rushton, AS Ward, RG Holdich: Solid-Liquid Filtration and Separation Technology, VCH Verlagsgesellschaft, Weinheim 1996, pages 177ff. . KJ Ives, in A. Rushton (ed.): Mathematical Models and Design Methods in Solid-Liquid Separation, NATO ASI Series E No. 88, Martinus Nijhoff, Dordrecht 1985, pages 90ff. ) and cross-flow filtrations (e.g. J. Altmann, S. Ripperger, J. Membrane Sci. 124 (1997), pages 119-128 ).

Likewise, the separation can be carried out by centrifugation. Usual centrifugation methods are z. In G. Hultsch, H. Wilkesmann, "Filtering Centrifuges," in DB Purchas, Solid-Liquid Separation, Upland Press, Croydon 1977, pp. 493-559 ; and H. Trawinski in "The Equivalent Clarifying Surface of Centrifuges, Chem. Ztg. 83 (1959), 606-612 described. Various designs such as tube and basket centrifuges and in particular push, inverting filter centrifuges and plate separators can be used.

Step c)

The lignin-containing liquid fraction obtained in the separation in step b), which contains the ionic liquid and the precipitant (F1) in addition to lignin, is subjected to a further separation. For this purpose, the lignin-containing liquid fraction obtained in step b), a second precipitant (F2) may be added, the lignin product is obtained as the second precipitate.

At least part of the precipitating agent (F1) may be removed prior to the addition of the precipitant (F2). The removal of at least part of the precipitating agent (F1) can be carried out by customary methods known to the person skilled in the art. The removal of at least part of the precipitant (F1) preferably takes place by evaporation. Suitable separation devices are the customary distillation columns and evaporators, such as. B. falling film evaporator, forced circulation flash evaporator, short path evaporator, thin film evaporator, wiper blade evaporator, Sambay evaporator, etc., and combinations thereof. Due to the low volatility of the ionic liquids can usually be dispensed with expensive devices, such as those used in the separation of mixtures with boiling points close to each other, such as complex column internals, columns with a high number of theoretical plates, etc. The removed precipitant (F1) is preferably used again as precipitant (F1) in step a) of the process according to the invention and / or as precipitant (F3) in step f) of the process according to the invention.

The second precipitant (F2) is preferably selected from solvents or solvent mixtures which are at least partially miscible with the ionic liquid used for the treatment of the lignocellulosic material in step a). Particularly preferably, the second precipitant (F1) is completely miscible with the ionic liquid.

Suitable lignin precipitating agents are, for. Water; Esters, e.g. For example, ethyl acetate; Ethers, e.g. For example, tetrahydrofuran, diethyl ether, methyl tert-butyl ether and diethylene glycol monomethyl ether; aliphatic solvents, e.g. Pentane, hexane, heptane, octane, ligroin, petroleum ether, cyclohexane and decalin. Preferably, hot water is used as the lignin precipitating agent. Preferably, the lignin phase is present as a precipitate. The lignin phase is then washed again with the lignin precipitant, preferably hot water.

The second precipitant (F2) used is preferably a solvent or solvent mixture selected from water, ethers, esters, aliphatic hydrocarbons and mixtures thereof.

The second precipitant (F2) is preferably selected from water, tetrahydrofuran, diethyl ether, methyl tert-butyl ether, diethylene glycol monomethyl ether, ethyl acetate, pentane, hexane, heptane, octane, ligroin, petroleum ether, cyclohexane, decalin and mixtures thereof.

Particular preference is given to using water as the second precipitant (F2).

The precipitant (F2) used for the precipitation in step c) preferably has a temperature of at least 50.degree. C., preferably at least 70.degree. C., in particular at least 90.degree. Especially preferred is hot water.

The separation of lignin-containing precipitate (second precipitate) and second liquid phase can be carried out by conventional separation methods, such as filtration, centrifugation or a combination thereof. The comments on these methods under step b) are fully incorporated by reference.

The second precipitate can (depending on the desired purity or intended use) be used directly as a lignin product. This includes z. Example, the use in a pyrolysis process for the production of aromatics with a lower number of aromatic rings and especially mononuclear aromatics.

If desired, the second precipitate may be subjected to at least one purification step. This includes treating with a liquid wash medium in which lignin does not substantially dissolve. Suitable washing media are the aforementioned second precipitating agents (F2). Particularly preferred as a liquid washing medium is water. The liquid washing medium preferably has a temperature of at least 50.degree. C., preferably at least 70.degree. C., in particular at least 90.degree. Especially preferred is hot water. For further workup, the liquid washing medium z. B. with the second precipitating agent (F2) are combined. The purified lignin can be subjected to drying by customary methods known to the person skilled in the art.

The second liquid phase obtained after separation of the second precipitate (ie the lignin product) contains the ionic liquid, the second precipitating agent (F2) and optionally at least part of the first precipitant (F1). For recovering the ionic liquid, at least part of the precipitating agent (F2) and, if present, at least part of the precipitant (F1) can be removed from the second liquid phase. The removal of the precipitant (s) (F2) and / or (F1) is preferably carried out by evaporation. Suitable separation devices are the aforementioned distillation columns and evaporators, such as. B. falling film evaporator, forced circulation flash evaporator, short path evaporator, thin film evaporator, wiper blade evaporator, Sambay evaporator, etc., and combinations thereof. The ionic liquid obtained is preferably used again as the treatment medium in step a) of the process according to the invention. The precipitants may, if appropriate after a further separation by distillation, also be used again in the process according to the invention.

As a rule, at least 80% by weight, particularly preferably at least 90% by weight, in particular at least 93% by weight, of the ionic liquid used in the treatment of the lignocellulose-containing starting material can be recovered by the above-described separation of the second liquid phase.

Step d)

The first precipitate obtained in step b) is treated with a liquid washing medium, wherein the hemicellulose is at least partially solubilized in the washing medium.

Preferably, in step d), the first precipitate is treated with a liquid wash medium containing or consisting of water.

The washing medium used for the treatment in step d) preferably has a temperature of at least 50.degree. C., more preferably at least 70.degree. C., in particular at least 90.degree.

The treatment of the first precipitate obtained in step b) with the liquid washing medium can take place one or more times in succession (for example twice or three times).

Steps)

From the first precipitate treated with the washing medium, the washing medium loaded with hemicellulose is separated off, the cellulosic product being obtained as a solid fraction.

Separation of cellulose product and hemicellulose-loaded wash medium may be accomplished by conventional separation techniques such as filtration, centrifugation or a combination thereof. The comments on these methods under step b) are fully incorporated by reference.

The resulting cellulose product can (depending on the desired purity or intended use) directly, ie without further workup and / or purification, are used. This includes z. As the use in the usual applications for pulps, z. In a specific embodiment, the cellulose product is subjected to enzymatic hydrolysis to produce a glucose product. Such methods and the further processing of the glucose product, for. B. to ethanol, are in the WO 2008/090156 to which reference is made in its entirety.

If desired, the cellulose product may be subjected to at least one cleaning step. This includes treating with a liquid washing medium in which cellulose essentially does not dissolve. Suitable washing media are the aforementioned first precipitating agents (F1). The purified cellulose product may be subjected to drying by conventional methods known to those skilled in the art.

Step f)

The liquid phase obtained after separation of the cellulose product (i.e., the loaded washing medium) contains hemicellulose.

According to the invention, a third precipitating agent (F3) is added to the hemicellulose-laden washing medium in step f) to give a third liquid fraction and, as the third precipitate, the hemicellulose product.

Suitable as the third precipitant (F3) are in principle all described under step b) first precipitant (F1), which is incorporated herein by reference in its entirety.

With particular preference, the third precipitant (F3) used is at least one alcohol. These include in particular methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol and mixtures thereof. Particular preference is given to using ethanol as the third precipitating agent (F3).

The third precipitant (F3) may additionally contain ionic liquids. This may be the case, for example, if it is reused precipitant from the process of the invention. The proportion of ionic liquid in the precipitating agent (F3) will generally be at most 50% by weight, more preferably at most 25%, based on the total weight of the third precipitating agent (F3). Such a content of ionic liquids is not critical to the success of hemicellulose precipitation.

The separation of lignin-containing fraction and cellulose and hemicellulose-containing precipitate can be carried out by conventional separation methods, such as filtration, centrifugation or a combination thereof. The description of these processes under step b) is fully incorporated by reference.

The hemicellulose product obtained can (depending on the desired purity or intended use) directly, d. H. without further work-up and / or purification. This includes z. As the use in cosmetics or for the production of chromatography materials.

If desired, hemicellulose product may be subjected to at least one purification step. This includes treating with a liquid washing medium in which hemicellulose essentially does not dissolve. Suitable washing media are the aforementioned third precipitating agents (F3) (corresponding to the first precipitating agent (F1)). The purified hemicellulose product may be subjected to drying by conventional methods known to those skilled in the art.

The invention will be further illustrated by the following non-limiting examples.

Example 1: Treatment of poplar wood with 1-ethyl-3-methylimidazolium acetate

a) Isolation of a cellulose and hemicellulose-containing precipitate and a lignin-containing liquid phase

150 g of poplar wood were stirred with 13.5 g of methanol and 2860.3 g of 1-ethyl-3-methylimidazoliumacetat at 100 ° C for 68 h. The solution was cooled to 60 ° C and treated with 1.5 kg of ethanol with vigorous stirring. Subsequently, the wood solution was added in 6 kg of ethanol. A precipitate formed, containing cellulose and hemicellulose.

The precipitate formed was separated by filtration from the lignin-containing liquid fraction and washed twice with 1 l of ethanol.

After washing with ethanol, the first precipitate was treated once with 6 liters of water at a temperature of 80 ° C and after separation of the washing water again with 1 liter of water at a temperature of 80 ° C. Further processing of the combined washing waters took place in step c).

As a purified precipitate, 142.3 g of cellulose was obtained.

b) Isolation of the lignin product

From the combined lignin-containing liquid fraction and the ethanolic washing liquid from step a), the ethanol was substantially completely removed by distillation. Subsequently, the lignin was precipitated by the addition of 3 liters of 80 ° C hot water. After filtration, the lignin was washed with water and dried.

3.39 g of lignin was obtained.

The combined liquid phases were concentrated using a Sambay evaporator. There were 2365.2 g of 1-ethyl-3-methylimidazoliumacetat with a water content of 6.4% and 404.1 g of 1-ethyl-3 methylimidazolium acetate with a water content of 9.2%. The recovered ionic liquid can be used again in step a) without further work-up.

c) isolation of hemicellulose

The combined washings from step a) were concentrated by means of a rotary evaporator to 569.3 g solvent content (70.7% water, 29.3% 1-ethyl-3-methylimidazoliumacetat). The concentrated solution was added to 4 L of ethanol to precipitate the contained hemicellulose. The precipitate formed was filtered off, washed twice with 250 ml of 40 ° C warm ethanol and then dried. There were obtained 4.64 g of hemicellulose. CPMAS NMR analysis is pure xylan.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CN 1806945 [0007]
• WO 2007/101812 [0008]
• WO 2009/071181 [0009]
• US 2007/0215300 A1 [0010]
• WO 2008/095252 [0012]
• WO 2008/112291 [0015]
• WO 2008/098032 [0016]
• WO 2007/111605 [0017]
• WO 2008/090155 [0043]
• WO 2008/090156 [0043, 0140]
• DE 10202838 A1 [0051]

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Claims (14)

A process for producing a cellulosic product, a hemicellulose product and a lignin product which comprises treating a lignocellulosic starting material with a liquid treatment medium comprising an ionic liquid, wherein the starting material is at least partially solubilized in the treatment medium and subjecting the solubilizate to fractional precipitation comprising at least comprises three precipitation steps. The method of claim 1, wherein a) providing a lignocellulosic starting material and treating it with a liquid treatment medium comprising an ionic liquid, wherein the starting material is at least partially solubilized in the treatment medium, b) adding to the solubilizate obtained in step a) a first precipitating agent (F1), whereby a lignin-containing liquid fraction and a first precipitate containing cellulose and hemicellulose are obtained, c) adding to the lignin-containing liquid fraction obtained in step b) a second precipitant (F2), the lignin product being obtained as second precipitate, d) treating the first precipitate obtained in step b) with a liquid washing medium, wherein the hemicellulose is at least partially solubilized in the washing medium, e) separating off the washing medium loaded with hemicellulose, the cellulosic product being obtained as a solid fraction, f) adding a third precipitating agent (F3) to the hemicellulose-laden washing medium obtained in step e), the hemicellulose product being obtained as the third precipitate. Process according to one of Claims 1 or 2, in which 1-ethyl-3-methylimidazolium acetate is used as the ionic liquid. A process according to any one of the preceding claims, wherein the liquid treatment medium used in step a) contains at least one cosolvent, which is preferably selected from C ₁ -C ₄ -alcohols, water and mixtures thereof. A method according to claim 4, wherein the proportion of cosolvent is at most 10 wt .-%, particularly preferably at most 5 wt .-%, based on the total weight of the liquid treatment medium. Method according to one of claims 4 or 5, wherein methanol is used as cosolvent. Method according to one of the preceding claims, wherein in step b) as the precipitant (F1) a solvent or solvent mixture is used, which is capable in combination with the ionic liquid to dissolve lignin. Method according to one of the preceding claims, wherein the precipitant (F1) comprises at least one C ₁ -C ₄ alcohol, preferably ethanol. Method according to one of the preceding claims, wherein in step c) water is used as precipitant (F2). Method according to one of the preceding claims, wherein the precipitating agent (F2) used for the precipitation in step c) has a temperature of at least 50 ° C, preferably at least 70 ° C, in particular at least 90 ° C. Method according to one of the preceding claims, wherein in step d) the first precipitate is treated with a liquid washing medium which contains water or consists of water. Method according to one of the preceding claims, wherein the washing medium used for the treatment in step d) has a temperature of at least 50 ° C, preferably at least 70 ° C, in particular at least 90 ° C. Method according to one of the preceding claims, wherein the precipitant (F3) used in step f) comprises at least one C ₁ -C ₄ -alcohol, preferably ethanol. A method according to any one of the preceding claims, wherein the hemicellulose product has a xylene content of at least 75%, preferably at least 90%, especially at least 95%, based on the total weight of the hemicellulose product.