method of separating hemicellulose and cellulose from polysaccharide sources

专利摘要:
METHOD OF SEPARATING HEMICELLULOSIS AND CELLULOSIS FROM POLYSACARIDE SOURCES. A method of separating hemicellulose and cellulose by dissolving hemicellulose from a source rich in hemicellulose, such as a pulp of any origin or from holocellulose. In the method, the hemicellulose is dissolved in a solvent system comprising a cellulose solvent, which is an ionic liquid or another direct cellulose solvent, and a molecular solvent (co-solvent), in which said co-solvent does not dissolve cellulose, and wherein the basicity of the solvent and the acidity of said ionic liquid or other direct cellulose solvent are suitably adjusted by the co-solvent. The present invention enables the quantitative separation of cellulose and hemicellulose without any depolymerization and loss of yield as occurs during conventional dissolving pulp manufacturing processes.
公开号:BR112014028353B1
申请号:R112014028353-2
申请日:2013-04-15
公开日:2020-12-01
发明作者:Herbert Sixta；Michael Hummel；Lasse Tolonen；Mikhail Iakovlev
申请人:Metsä Spring Oy；
IPC主号:

专利说明:

[0001] [0001] The invention relates to the separation of hemicellulose and cellulose from polysaccharide sources. In particular, the present invention relates to methods of separating hemicelluloses and cellulose from a source rich in hemicellulose, such as a pulp of any origin or from holocellulose by dissolving it in suitable solvents. The present invention also relates to dissolving pulps. Background
[0002] [0002] Dissolving pulp refers to pulp with a high cellulose content that is used as a raw material for the manufacture of cellulose derivatives and regenerated cellulose products. Dissolving pulps derived from wood that account for approximately 85% of the total dissolving pulp market are produced according to the acid sulfite and pre-hydrolysis-kraft (PHK) processes. In both cases, additional purification steps such as caustic hot and cold extractions are necessary to achieve the necessary degree of purification (determined as the residual hemicellulosis content and alkaline resistance). Removal of hemicellulose is associated with severe cellulose losses mainly due to peeling reactions. Cellulose losses comprise between 15 and more than 30% by weight depending on the process and the degree of purification. The hemicelluloses removed are largely converted to hydroxy acids of low molar mass due to alkaline post-extraction processes that constitute another drawback of current technologies. Cotton fibers account for the residual market of 15% of the dissolving pulp and represent the dissolving pulp with the highest cellulose purity. They are particularly used for the production of acetate plastics and high DP cellulose ethers.
[0003] [0003] Unlike the paper pulp market, the soluble cellulose market has shown a consistent annual growth of around 5% since the last 10 years after the man-made cellulose fiber industry consolidated during the 1990s. This growth is largely caused by the installation of new viscose fiber capacities in Asia, but increasingly also due to new cellulose products that require high purity dissolving pulps. At the same time, the availability of cotton fibers does not keep up with the increase in demand for several reasons.
[0004] [0004] It is estimated that the annual demand for soluble cellulose will increase from the current 5-6 million tons to around 12-20 million tons in 2050, at least. This clearly underlines the need for new, environmentally friendly and economically attractive production processes for high-purity dissolving pulps, which allow the concurrent recovery of hemicelluloses in high yield and purity. Summary of Invention
[0005] [0005] It is an objective of the present invention, to provide a medium for selectively and (almost) quantitatively dissolved hemicelluloses from a pulp rich in hemicellulose of any origin as well as from holocellulose in an ionic liquid of which the basicity of the solvent and the acidity are suitably adjusted by the addition of a co-solvent.
[0006] [0006] The basicity of the solvent and the acidity are characterized by the Kamlet-Taft (KT) solubility parameters, primarily the values β (H-binding basicity) and α (H-binding acidity), respectively.
[0007] [0007] Thus, the present invention relates to a method for separating hemicellulose and cellulose by dissolving hemicellulose from a pulp rich in hemicellulose of any origin or from holocellulose.
[0008] [0008] In the present method hemicellulose is dissolved in a solvent system comprising a cellulose solvent, which is an ionic liquid or another direct cellulose solvent, and a molecular solvent (co-solvent), wherein said co-solvent it does not dissolve cellulose, and in which the basicity of the solvent and the acidity of said ionic liquid or other direct cellulose solvent are suitably adjusted by the co-solvent.
[0009] [0009] In another aspect, this invention relates to a method for the separation of hemicellulose and cellulose by dissolving hemicellulose from a pulp rich in hemicellulose of any origin or from holocellulose, in which the hemicellulose is dissolved in a solvent system comprising an ionic liquid and a molecular solvent (co-solvent), in which said co-solvent does not dissolve cellulose and in which the basicity of the solvent and the acidity of said ionic liquid are suitably adjusted by the co-solvent.
[0010] [0010] In a third aspect, the present invention relates to dissolving pulps.
[0011] [0011] More specifically, the present method is mainly characterized by which it is indicated in the characterization part according to claims 1 and 2.
[0012] [0012] The dissolving pulps are characterized by which it is indicated in the characterizing part according to claims 22. Benefits
[0013] [0013] The present invention enables the quantitative separation of cellulose and hemicellulose without any depolymerization and loss of yield as occurs during conventional dissolving pulp manufacturing processes. The invention facilitates the integration of pulp refining in a cellulose regeneration process (IONCELL). Hemicelluloses are dissolved by a solvent system with adjusted solubility parameters instead of being fragmented by acidic or alkaline catalyzed degradation pathways (acid sulphite process combined with hot caustic extraction or pulp by kraft prehydrolysis with or without powders alkaline extraction).
[0014] (a) Processo simples, de baixo consumo de energia: tratamento de dissolução a temperatura ligeiramente elevada em um sistema de solventes que é igualmente adequado para dissolução de celulose, celulose + hemicelulose ou somente hemicelulose. Desta maneira esta invenção pode ser expandida a processos de regeneração de celulose. (b) Não há perdas de rendimento de tanto hemicelulose como celulose: no mesmo nível de pureza de celulose, o processo convencional de pré-hidrólise-kraft experimenta 5 a 10 % de perda de rendimento de celulose em madeira seca no forno dependendo da fonte de madeira e extensão de pureza de celulose. O mesmo se aplica ao processo de obtenção de polpa de sulfito ácido. Hemiceluloses poliméricas não podem ser recuperadas com os processos existentes de fabricação de polpa em dissolução. No entanto, o processo de sulfito ácido possibilita separar os mono-açúcares dissolvidos do licor residual de sulfito (SSL). [0014] Some important advantages are: (a) Simple, low energy consumption process: dissolution treatment at slightly elevated temperature in a solvent system that is equally suitable for dissolving cellulose, cellulose + hemicellulose or only hemicellulose. In this way, this invention can be expanded to cellulose regeneration processes. (b) There are no yield losses from both hemicellulose and cellulose: at the same level of cellulose purity, the conventional pre-hydrolysis-kraft process experiences 5 to 10% loss of cellulose yield in oven-dried wood depending on the source wood and cellulose purity extension. The same applies to the process of obtaining acid sulfite pulp. Polymeric hemicelluloses cannot be recovered with existing dissolving pulp manufacturing processes. However, the acid sulfite process makes it possible to separate the dissolved mono-sugars from the residual sulfite liquor (SSL).
[0015] [0015] c) The invention suggests the use of a cellulose solvent that can also be used in a conversion process, for example, the cellulose regeneration process. This makes it possible to combine the pulp refining process (invention) with a fiber or film formation process using the dry-wet regeneration concept as suggested by the IONCELL process as mentioned earlier. Brief Description of Drawings Figure 1: Simplified fractionation scheme for a hemi-rich pulp in fractions of cellulose and hemicellulose; Figure 2: Cationic fractions of ionic liquids suitable for pulp dissolution; Figure 3: Liquid basicity, (β-α), versus basicity (β) of [emim] [OAc] mixed with increasing amount of co-solvent. The co-solvent is water. Kamlet-Taft (KT) parameters were determined at room temperature; Figure 4: Glucan and xylan yields in solid waste as a function of water content. The results are expressed in% by weight of the amounts of glucan and xylan in the initial pulp; Figure 5: Molar mass distribution of the initial bleached birch kraft pulp, the pulp residue (pulp dissolving, that is, pure cellulose), the precipitate (pure hemicellulose extracted) and the calculated sum of the fractions. The treatment was carried out in [emim] [OAc] -water with 15% by weight water at 60 ° C for 3 h; Figure 6: Molar mass distribution of the initial pulp of bleached pine kraft, the pulp residue (pulp dissolving, ie cellulose), the precipitate (hemicellulose) and the calculated sum of the fractions. The treatment was carried out with [emim] [OAc] -water with 15% by weight water at 60 ° C for 3 h. Description of Modalities
[0016] [0016] As previously discussed, the present technology provides an innovative way to separate hemicellulose and cellulose by dissolving hemicellulose from a source rich in hemicellulose in a solvent system comprising a cellulose solvent, which is an ionic liquid or another direct cellulose solvent, together with a molecular solvent (co-solvent). The co-solvent is selected such that it does not dissolve cellulose. The basicity of the solvent and the acidity of said ionic liquid or other direct cellulose solvent are suitably adjusted by the co-solvent.
[0017] [0017] The basicity of the solvent and the acidity are characterized by the Kamlet-Taft solubility parameters, particularly by the values of β (H-binding basicity) and α (H-binding acidity).
[0018] [0018] To give some specific examples of preferred modalities, in a first modality, the ionic liquid is a direct cellulose solvent, which has a cation selected from the group of cationic fractions represented in Figure 2, in which residues R1- 5 are independently linear or branched alkyl- (typically C1-C6), alkoxy-, or alkoxyalkyl groups, residues containing aryl fractions, or hydrogen, and an anion selected from the group consisting of halides (fluoride, chloride, bromide and iodide ), pseudohalides (cyanide, thiocyanide, cyanate), carboxylates (formate, acetate, propionate, butyrate), alkyl sulfite, alkyl sulfate, trifluoromethane sulfonate, phenyl sulfonate, dialkyl phosphite, dialkyl phosphate, dialkyl phosphonites and dialkyl phosphonates.
[0019] [0019] In a preferred embodiment, the ionic solvent has a liquid basicity (β-α) in the range of 0.11-0.47; and a β value in the range of 0.57-0.95; preferably a liquid basicity (β-α) in the range of 0.24-0.39; and a β value in the range of 0.70-0.88.
[0020] [0020] In the present technology, the ionic liquid can also be replaced by NMMO.H2O or LiCl / DMAc.
[0021] [0021] The co-solvent is preferably miscible with the ionic liquid. In particular, the co-solvent is able to decrease the β value and / or increase the α value of the solvent system.
[0022] [0022] Preferably, the co-solvent is selected from the group consisting of water, methanol, ethanol, propanol, iso-propanol, butanol, acetone, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide and dimethylimidazolidione, preferably co- solvent is water or ethanol.
[0023] [0023] In a particular embodiment, the co-solvent comprises another ionic liquid which is not capable of dissolving cellulose, so that this mixture of co-solvent and IL consists of a cation mentioned above and any anion does not mentioned earlier, preferably of the hexafluorophosphate, tetrafluoroborate, bis (trifluoromethane) sulfonimide type.
[0024] [0024] Preferably, the ionic liquid is an ionic liquid based on [emim].
[0025] [0025] Specific examples of ionic liquid are as follows: [emim] [OAc], [bmim] [OAc], [emim] [DMP] and [DEP], [DBNH] [OAc], [DBNH] [EtOAc] , preferably [emim] OAc and [emim] [DMP].
[0026] [0026] The co-solvent (to be combined with any of the previous ionic liquids is water or an alcohol, preferably water, where the water content is preferably in the range of 10-30% by weight, and the solvent has a basicity liquid (β-α) in the range of 0.11-0.47; and a value of β in the range of 0.57-0.95; preferably a liquid basicity (β-α) in the range of 0.24-0 , 39; and a β value in the range of 0.70-0.88.
[0027] [0027] The present method can be carried out, for example, at a temperature ranging from 20-150 ° C, preferably 40-80 ° C for a time ranging from 10-400 min, preferably 60-180 min.
[0028] [0028] Pulp consistency can vary over wide ranges, typically being approximately 1-25% by weight, preferably 5-15% by weight.
[0029] [0029] The hemicellulose-rich pulp used as a starting material can be any bleached or unbleached paper pulp of any lignocellulosic raw material derived from any commercial (sulfite, kraft, Soda-AQ) or non-commercial process, such as organosolv , carboxylic acid, ASAM, ASA or MEA, although these examples are not exhaustive.
[0030] [0030] The dissolved hemicellulose fraction can be regenerated by the addition of a non-solvent, preferably water or alcohol, and the precipitate is separated by filtration or centrifugation.
[0031] [0031] In an additional embodiment, the dissolved hemicellulose fraction is separated by means of pressure-directed membrane processes, and / or a non-solvent is added to the hemicellulose-enriched retentate to initiate hemicellulose precipitation, and the hemicellulose is recovered as a pure powder after washing and drying.
[0032] [0032] Based on the previous modalities, a cellulose product can be obtained that has a residual hemicellulose content of 1.0 to 10% by weight, preferably between 2.0 and 5.0% by weight, and the hemicellulose alone and purified has a residual cellulose content between 1.0 and 10% by weight, preferably between 2.0 and 5% by weight.
[0033] [0033] Typically, cellulose and hemicellulose contents are calculated using Janson's formulas, and the neutral sugar content is determined by HPAEC-PAD as described in reference [10].
[0034] [0034] The cellulose-rich residue can, for example, be dissolved in a cellulose solvent as mentioned earlier.
[0035] [0035] Modifications of the previous methods are possible. Thus, for example, oxidants or acids can be added to the cellulose lubricant to adjust the degree of polymerization suitable for subsequent formation and regeneration processes. The amount of such oxidants or acids is typically from 0.001 to 10% by weight of the total composition.
[0036] [0036] The oxidants added to the cellulose lubricant can be selected so as to be able to remove chromophores such as residual lignin, HexA and extracts before conversion processes.
[0037] [0037] The treated cellulose lubricant is subjected to filtration to remove undissolved impurities.
[0038] [0038] Referring now to the drawings, it can be seen that Figure 1 shows a simplified scheme of the fractionation process. Thus, in the scheme, the pulp was treated with a solvent system in a vertical kneader (or a smaller scale shaker) at various temperatures (60-80 ° C) and retention times (0.5-6 h). The solvent system consisted of a mixture of [emim] [OAc] - water with a water content ranging between 10% by weight and 30% by weight. The resulting suspension was filtered (separated) with a filter press (or a centrifuge). The dissolved xylan was precipitated by the additional addition of water (non-solvent). The washed and dried cellulose and xylan fractions were analyzed.
[0039] [0039] Solvent systems typically comprise an ionic liquid and a molecular solvent of which the latter is normally used in smaller parts and thus can be easily removed to regenerate the ionic liquid. The concept presented in this document is valid for all ionic liquids that have been reported as cellulose solvents. This in particular comprises ionic liquids with cationic fractions as shown in Figure 2. Residues R1-5 are independently linear or branched alkyl- (typically C1-C6), alkoxy-, or alkoxyalkyl groups, residues containing aryl fractions, or hydrogen.
[0040] [0040] The preferred anions of ionic liquids are halides (fluoride, chloride, bromide and iodide), pseudohalides (cyanide, thiocyanide, cyanate), carboxylates (formate, acetate, propionate, butyrate), alkyl sulfite, alkyl sulfate, sulfonate of trifluoromethane, phenyl sulfonate, dialkyl phosphite, dialkyl phosphate, dialkyl phosphonites, dialkyl phosphonates (Fig. 2). Thus, the resulting ionic liquid is hydrophilic and its Kamlet-Taft basicity and liquid basicity suitable for cellulose dissolution [7].
[0041] [0041] To generate a solvent system that allows for the fractionation of holocellulose mentioned above, the ionic liquid is mixed with a co-solvent. Any solvent that does not dissolve cellulose alone can be used as a co-solvent to generate a selective solvent system. The preferred co-solvents are miscible with the respective ionic liquid and decrease the β value (and / or increase the α value, respectively) of the resulting solvent mixture. Preferably, the co-solvent is water, methanol, ethanol, propanol, iso-propanol, butanol, acetone, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, dimethylimidazolidione. The co-solvent may also comprise another ionic liquid which is not capable of dissolving cellulose alone. This co-solvent-IL consists of a previously mentioned cation and any anion not previously mentioned, preferably of the hexafluorophosphate, tetrafluoroborate, bis (trifluoromethane) sulfonimide type. For reasons of environmental and energy savings, water and ethanol are used most preferably.
[0042] [0042] In addition to ionic liquids also other direct cellulose solvents, preferably NMMO.H2O and LiCl / DMAc, are suitable for the selective dissolution of low molar mass polysaccharides such as hemicelluloses or low molar mass cellulose from a rich pulp in hemicellulose when mixed with a co-solvent - as previously listed - in a ratio such that the targeted solvent parameters (liquid basicity, β value) are properly adjusted.
[0043] [0043] Kamlet-Taft (KT) parameters have proven to be useful solvent property indicators [1]. They are determined from the absorption peaks of the three Reichardt dye dyes (RD, range 518-585 nm), N, N-diethyl-4-nitroaniline (DENA, 402-414 nm) and 4-nitroaniline (NA , 406-398 nm). The peaks are typically adjusted to a Gaussian function in order to precisely locate the maximums (Vmax). From these Vmax (T) functions, the parameters Et (30), π *, α and β are calculated using published equations [2].
[0044] [0044] Several authors have demonstrated that the basicity of H binding, expressed by the value of β, correlates with the ability of an ionic liquid to dissolve cellulose [2-6]. Other KT values were not found that directly correlate with cellulose dissolution.
[0045] [0045] Quite recently, we introduced the term liquid basicity, β-α, which allows a better prediction of both cellulose dissolution and regeneration since it accounts for the acidity conferred by the cation or a protic co-solvent [7]. Based on a representative selection of cellulose solvents, it was shown that cellulose dissolution generally complies with the requirement of 0.35 <β-α <0.9 with β> 0.8 [7]. With the progressive addition of a protic co-solvent such as water or alcohol the basicity of H, β binding decreases while the acidity of the H, α binding increases. This was demonstrated by adding water to [emim] [OAc]. As shown in Figure 3, the liquid basicity decreases faster than the β value due to the opposite development of the α and β values with the increasing amount of water in [emim] [OAc]. In addition, Figure 3 reveals the ranges of KT-derived parameters of solubility indicating complete and partial dissolution of quality pulp hemicelluloses for paper.
[0046] [0046] As expected, the solubility of a hemicellulose-rich pulp decreases with an increasing percentage of water in a mixture of [emim] [OAc] -water when treated for three hours at approximately 60 ° C in a vertical kneader.
[0047] [0047] Surprisingly, the extent of pulp dissolution decreases only gradually with increasing concentration of water in [emim] [OAc]. This was not expected since for some ionic liquids, for example, for [bmim] Cl, TMG-based ILs and others, it was known that the presence of only marginal amounts of water resulted in a complete stop of their ability to dissolve uniform fractions of a pulp [7] [9]. The mixture of [emim] [OAc] -water, however, revealed a high dissolving power even in relatively high water concentration. This was, for example, demonstrated for a bleached kraft pulp of which 60% by weight, 28% by weight, 20% by weight, 13% by weight and 1% by weight were dissolved in a mixture of [emim] [OAc] -Water with a water content of 10% by weight, 15% by weight, 20% by weight, 25% by weight and 30% by weight, respectively. In addition to the 30% by weight water in [emim] [OAc] -water the dissolution of any component of the pulp stops.
[0048] [0048] Closer examination confirmed that the extent of dissolution and thus the dissolving power of the solvent system was mainly related to the molar mass of the pulp components. Factors such as pulp morphology, supramolecular structure, degree of crystallinity and chemical properties (for example, affecting hydrophilicity) of the pulp components that are likely to affect the solution's behavior as well. The removal of pure cellulose and hemicellulose hemifractions from the paper pulp was, however, unpredictable despite the expected pulp fractionation behavior dependent on the molar mass of the [emim] [OAc] -water solvent. The solvent properties of the appropriate [emim] [OAc] -water mixtures were obviously more favorable for the extraction of hemicellulose than for cellulose of comparable molar mass.
[0049] [0049] The results shown in Figure 4 clearly indicate that the xylan in a birch kraft pulp is more efficiently and selectively dissolved in [emim] [OAc] containing 15-20% by weight of water. In addition to the water content of the solvent system, hemicellulose dissolution efficiency and selectivity were also affected by the dissolution conditions. This has been demonstrated for a solvent mixture containing 20% by weight of water. The results of different dissolution conditions for this particular water content of the solvent mixture are included in Figure 4. The detailed results are shown in Example 3.
[0050] [0050] Based on the above, dissolving cellulose pulps are provided, in which the cellulose pulps have a residual hemicellulose content of 1.0 to 10% by weight.
[0051] [0051] Thus, a dissolving cellulose pulp obtained using a method as explained above, in which the isolated and purified hemicellulose is taken from a source rich in hemicellulose, exhibits a residual cellulose content between 1.0 and 10% by weight, preferably between 2.0 and 5% by weight, the cellulose and hemicellulose contents being calculated using the Janson formulas, and the neutral sugar content are determined by HPAEC-PAD as described in reference [10].
[0052] [0052] The following non-limiting examples illustrate the invention, Example 1 Effect of water content in [emim] [OAc] on the fractionation of a commercial birch kraft pulp: Pulp residue composition
[0053] [0053] EFC bleached birch kraft pulp was treated with a mixture of [emim] [OAc] -water [from 10% by weight to 30% by weight] in a horizontal kneader for 3 h at 60 ° C. The subsequent phase separation was carried out with a filter press equipped with metallic wool. The pore diameter was in the range of 1-5 μm. The pulp residue was thoroughly washed with water, dried and subjected to analysis. Alternatively, the dissolution was supported by a stirrer and the phase separation by means of centrifugation. The results are summarized in Table 1.
[0054] [0054] Table 1: Effect of water content in [emim] [OAc] on xylan removal efficiency and selectivity. Pulp residue characterization.
[0055] [0055] The soluble fractions generated in Example 1 were precipitated by the addition of excess water (anti-solvent). The precipitated, extracted polysaccharides were centrifuged and washed thoroughly to remove residual ionic liquid. The washed precipitates were dried at room temperature overnight or, alternatively, by lyophilization. Table 2 shows the yield and composition of the extracted molar mass pulp fractions.
[0056] [0056] Table 2: Effect of water content in [emim] [OAc] on the yield and purity of the extracted pulp fraction. Characterization of the precipitate from the soluble fraction.
[0057] [0057] Table 2 shows that between a water content of 10 to 15% by weight in [emim] [OAc] the transition from cellulose / hemicellulose to extraction of pure hemicellulose occurs. Thus, in the range of 15% by weight to 25% by weight of water, basically only hemicellulose is extracted. Quantitative hemicellulose extraction is achieved in the range of at least 15% by weight and 20% by weight of water content in [emim] [OAc]. Example 3 Effect of dissolution conditions at a constant water content of 20% by weight in [emim] [OAc] on fractionation efficiency and selectivity of a commercial birch kraft pulp
[0058] [0058] In a series of experiments, where the water content was kept constant at 20% by weight in [emim] [OAc], the effects of temperature, time and mixing conditions on the fractionation of a bleached birch kraft pulp were determined (table 3).
[0059] [0059] Table 3: Effect of temperature, time and mixing conditions at a water content of 20% by weight in [emim] [OAc] on the yield and purity of the pulp residue
[0060] [0060] The support through the longer retention time, higher temperature and the concomitant application of ultrasonication revealed a clear impact on the yield and purity of the pulp residue.
[0061] [0061] High temperature (80 ° C, 3 h) or moderate temperature combined with long dissolution time (60 ° C, 6 h) show significantly better xylan dissolution efficiency compared to standard conditions (60 ° C, 3 h) . In addition, the ultrasonication dissolution support appears to significantly improve the efficiency / selectivity of xylan removal. The xylan content of the pulp residue decreases to only 1.5 to 1.8% od, which meets the requirements for standard acetate grade pulps. Example 4 Pulp consistency effect in the [emim] [OAc] -water solvent system in the fractionation efficiency and selectivity of a commercial birch kraft pulp.
[0062] [0062] The consistency of the pulp in a suspension or solution has an important impact on the economic feasibility of a process. Most experiments were conducted at a low consistency of 3.3% by weight to facilitate the handling of the pulp solvent system in the laboratory. The pulp consistency was increased to 10.5% by weight in a separate experiment with bleached birch kraft pulp using [emim] [OAc] with a water content of 15% by weight. The results are compared with those obtained with a pulp consistency of only 3.3% by weight in Table 4.
[0063] [0063] Table 4: Effect of pulp consistency at a water content of 15% by weight in [emim] [OAc] on the yield and purity of the pulp residue
[0064] [0064] In addition to the residue yield, which was very difficult to determine, the performance at 10.5% by weight of consistency was comparable to that at 3.3% by weight of consistency (the yield of the first is more reliable considering the mass balance). Evidence of the quantitative and highly selective fractionation of cellulose and hemicellulose from a pulp rich in hemicellulose was provided by the comparative evaluation of the molar mass distributions of the initial pulp, the cellulose and hemicellulose fractions and their calculated sums. Thus, it was shown that fractionation occurs in a highly selective and quantitative way. Thus, no degradation of cellulose or hemicellulose has been observed to occur during conventional dissolving pulp processes. Example 5 Effect of wood raw material: Birch versus Pine kraft pulp
[0065] [0065] The fractionation performance of the [emim] [OAc] -water solvent system with a water content of 15% by weight has been investigated for a pine kraft pulp compared to a birch kraft pulp. The results are summarized in Table 5.
[0066] [0066] Table 5: Effect of raw material wood from a paper grade kraft pulp on the yield and purity of the pulp residue. Treatment Conditions: 85% by weight [emim] [OAc] +15% by weight water, 60 ° C, 3 h in a kneader, phase separation with a filter press
[0067] [0067] The successful separation of cellulose and hemicelluloses from a pine kraft pulp is also reflected in its molar mass distributions (Figure 6). From the results it can be concluded that kraft pulps, coniferous wood and hardwood are also suitable as a substrate for the quantitative separation of hemicellulose and cellulose applying the process according to the present invention. Industrial applicability
[0068] [0068] Examples 1-5 confirm the feasibility of the innovative concept of fractionation concept of pulp rich in hemicelluloses (holocellulose, pulps with paper grade) using a mixture of -co-solvents and IL with suitable solvent parameters as expressed by the parameters of KT and appropriate dissolution conditions (Figure 3).
[0069] [0069] With reference to the work in the conditions of cellulose dissolution [7] it can now be proposed to enable the dissolution of complete and partial hemicelluloses from hemicellulose-rich polysaccharides, preferred from bleached paper grade pulps.
[0070] [0070] Figure 3 shows the solubility window for complete hemicellulosis dissolution (β-α = 0.24 - 0.39; β = 0.70 - 0.88) and complete and partial (β-α = 0.11 - 0.47; β = 0.57 - 0.95).
[0071] [0071] The appropriate solvent properties have been conveniently adjusted by adding water to [] [OAc]. However, the fractionation concept can be successfully transferred to any cellulose solvent-co-solvent mixture with the provision that the solubility parameters meet the requirements as defined for the hemicellulose dissolution window (complete and partial) ).
[0072] [0072] Different from the conventional and innovative fractionation schemes for the manufacture of pulp in dissolution using chemical reactions, the proposed invention allows a quantitative separation of hemicelluloses and high purity cellulose without any losses and the depolymerization of the associated polymers.
[0073] [0073] Supporting extraction by high intensity mixing at high temperature promotes fractionation efficiency and selectivity as exemplified in Table 3.
[0074] [0074] The quantitative separation of cellulose and hemicellulose from pulp rich in hemicelluloses or holocellulose, is incorporated in a new concept of process, IONCELL, which, as a first step, comprises the separation of hemicellulose from the substrate rich in original hemicellulose. Step 2 of the IONCELL process is characterized by the separation of the dissolved hemicellulose after the phase separation. The separation is preferably conducted by membrane separation to avoid any further dilution of the solvent (for example, ionic liquid).
[0075] Alternatively, the addition of a non-solvent, preferably equivalent to the co-solvent (for example, water), is added to the solution to precipitate hemicellulose (Figure 1). Proper filtration of the generated hemicellulose / solvent / co-solvent suspension guarantees quantitative phase separation. The filtered hemicellulose is washed and dried while the solvent / non-solvent mixture is recycled to the fractionation process after the co-solvent content has been adjusted to the desired value.
[0076] [0076] In a third stage, the fraction of purified cellulose is dissolved in a cellulose solvent, for example, ionic liquid, recycled from the conversion (fiber, film) or from a fractionation process. The lubricant can also be treated with oxidizers (bleaching chemicals such as hydrogen peroxide, ozone and others) to remove impurities (bleaching) in the case of an unbleached pulp as the initial substrate and / or to adjust the degree of polymerization as required by the subsequent training and regeneration. These processes primarily comprise the production of regenerated fibers and films.

权利要求:
Claims (17)
[0001]
Method for separating hemicellulose and cellulose by dissolving hemicellulose from a source rich in hemicellulose, such as a pulp of any origin or from holocellulose, characterized by the fact that the hemicellulose is dissolved in a solvent system comprising a solvent of cellulose, which is an ionic liquid or another direct cellulose solvent, and a molecular solvent (co-solvent), in which said co-solvent does not dissolve cellulose, and in which the basicity of the solvent and the acidity of said ionic liquid or other direct cellulose solvent are suitably adjusted by the co-solvent.
[0002]
Method according to claim 1, characterized by the fact that hemicellulose is dissolved in a solvent system comprising an ionic liquid and a molecular solvent (co-solvent), in which said co-solvent does not dissolve cellulose and in which the basicity of the solvent and the acidity of said ionic liquid are adequately adjusted by the co-solvent.
[0003]
Method according to any one of claims 1 and 2, characterized by the fact that the basicity of the solvent and the acidity are defined by the Kamlet-Taft solubility parameters, particularly by the values β (basic binding H) and α ( binding acidity of H).
[0004]
Method according to any one of claims 1 to 3, characterized by the fact that said co-solvent is miscible with the ionic liquid and optionally, said co-solvent is able to decrease the value of β and / or increase the α value of the solvent system.
[0005]
Method, according to any of the previous claims, characterized by the fact that i) the ionic liquid is a direct cellulose solvent, which preferably has - a cation selected from the group of cationic fractions represented by the following formulas:
[0006]
Method according to any one of the preceding claims, characterized by the fact that the co-solvent is selected from the group consisting of water, methanol, ethanol, propanol, iso-propanol, butanol, acetone, acetonitrile, dimethyl sulfoxide , dimethylformamide, dimethylacetamide and dimethylimidazolidione, preferably the co-solvent is water or ethanol or the co-solvent comprises another ionic liquid which alone is not capable of dissolving the cellulose, so that this mixture of co-solvent and ionic liquid consists of a previously mentioned cation and any anion not previously mentioned, preferably of the hexafluorophosphate, tetrafluoroborate, bis (trifluoromethane) sulfonimide type.
[0007]
Method according to any one of the preceding claims, characterized by the fact that the ionic solvent has a liquid basicity (β-α) in the range of 0.11-0.47; and a β value in the range of 0.57-0.95; preferably a liquid basicity (β-α) in the range of 0.24-0.39; and a β value in the range of 0.70-0.88.
[0008]
Method according to any of the preceding claims, characterized by the fact that the ionic liquid is an ionic liquid based on [emim].
[0009]
Method according to any of the preceding claims, characterized by the fact that the ionic liquid is [emim] [OAc], [bmim] [OAc], [emim] [DMP], [DEP], [DBNH] [OAc ], [DBNH] [EtOAc], preferably [emim] OAc, or [emim] [DMP], the co-solvent is water or an alcohol, preferably water, where the water content is preferably in the range of 10-30 % by weight, and the solvent has a liquid basicity (β-α) in the range of 0.11-0.47; and a β value in the range of 0.57-0, 95; preferably a liquid basicity (β-α) in the range of 0.24-0.39; and a β value in the range of 0.70-0.88.
[0010]
Method according to any one of the preceding claims, characterized in that the method is carried out at a temperature ranging from 20-150 ° C, preferably 40-80 ° C for a time ranging from 10-400 minutes, preferably 60-180 minutes, and preferably at a pulp consistency of 1-25% by weight, in particular 5-15% by weight.
[0011]
Method according to any one of the preceding claims, characterized by the fact that the pulp rich in hemicellulose used as a starting material is bleached or unbleached paper pulp of any lignocellulosic raw material derived from any commercial processes (sulfite, kraft, Soda-AQ) or non-commercial, such as organosolv, carboxylic acid, ASAM, ASA or MEA.
[0012]
Method according to any one of the preceding claims, characterized in that the fraction of dissolved hemicellulose is regenerated by the addition of a non-solvent, preferably water or alcohol, and the precipitate is separated by filtration or centrifugation.
[0013]
Method, according to any of the previous claims, characterized by the fact that - the fraction of dissolved hemicellulose is separated by means of membrane processes conducted by pressure, and / or - a non-solvent is added to the reticate enriched with hemicellulose to initiate precipitation of the hemicellulose, and - hemicellulose is recovered as a pure powder after washing and drying.
[0014]
Method, according to any of the previous claims, characterized by the fact that - the final cellulose product obtained has a residual hemicellulose content of 1.0 to 10% by weight, preferably between 2.0 and 5.0% by weight, and - isolated and purified hemicellulose has a residual cellulose content between 1.0 and 10% by weight, preferably between 2.0 and 5% by weight, in which the cellulose and hemicellulose contents are calculated using the Janson formulas, and the neutral sugar content is determined by HPAEC-PAD as described in H. Sixta et al. (reference [10]).
[0015]
Method according to any one of the preceding claims, characterized by the fact that the cellulose-rich residue is dissolved in a cellulose solvent as mentioned above.
[0016]
Method according to any one of the preceding claims, characterized in that oxidants or acids are added to the cellulose lubricant to adjust the degree of polymerization suitable for the subsequent formation and regeneration processes, and / or oxidants are added to the lubricant of cellulose to remove chromophores such as residual lignin, HexA and extractives before conversion processes.
[0017]
Method according to any one of claims 14 and 15, characterized in that the treated cellulose lubricant is subjected to filtration to remove undissolved impurities.

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同族专利:

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公开号 | 公开日

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CA2873106C|2018-03-20|

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EP2850109B1|2017-08-16|

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EP2850109A1|2015-03-25|

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CN104619728B|2017-12-29|

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CA2873106A1|2013-11-21|

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US20150107790A1|2015-04-23|

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WO2013171364A1|2013-11-21|

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CN104619728A|2015-05-13|

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BR112014028353A2|2017-07-18|

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法律状态:
2018-03-27| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2019-03-19| B25A| Requested transfer of rights approved|Owner name: METSAE SPRING OY (FI) |

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2019-11-05| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2020-09-08| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2020-12-01| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 15/04/2013, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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US201261646383P| true| 2012-05-14|2012-05-14|

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US61/646,383|2012-05-14|

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PCT/FI2013/050414|WO2013171364A1|2012-05-14|2013-04-15|Method of separation of hemicellulose and cellulose from polysaccharide sources|

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