WO1979000119A1 - Process allowing the delignification and the transformation into sugar of lignocellulose vegetal materials by using organic solvents - Google Patents

Abstract

Minced lignocellulose, such as wood, straw, bamboos, bagasse or any other structured vegetal material, is treated in a discontinuous or continuous process. The process consists in boiling this material in an acidified mixture of solvents in an aqueous phase. This mixture of solvents contains water in a proportion of 30 to 70 parts and an organic solvent in a proportion of 70 to 30 parts. The organic solvent consists of either an alcohol of light molecular weight, or a ketone of light molecular weight; it must be easily evaporable and soluble in water. The pH of the medium is adjusted to a pH from 3.5 to 1.7 by adding a catalytic compound selected within the group of the strong acids: hydrochloric, nitric and phosphoric; within the group of these strong acids neutralized by their neutral salts; within the group of the following organic acids: oxalic, maleic, o-phthalic, l-malic, succinic, nicotinic, salicylic and trifluoracetic. The boiling temperatures range between 160 and 210 C, preferably between 180 and 200 C. After three minutes at the minimum, we obtain the separation of the lignin and the hydrolysis of the hemicelluloses dissolved; after that, the fibres are easily dispersible while forming a pulp. By proceeding to a mechanical refining at a high pressure, a high density thermomechanical pulp is obtained after a shorter boiling time. With the neutralized acids, as well as with the organic acids, particularly with the oxalic acid, we can obtain a fibre with a high degree of polymerization. The lignin is obtained as a precipitate which separates from the liquid; the liquid solvent, usually ethanol or acetone, is evaporated; then the drained lignin is redissolved in the minimal quantity of acetone; a new precipitation with an excess of water allows to obtain the lignin in the form of a slightly coloured powder. A prolonged boiling dehydrates and disaggregates the sugars; by the strong acids action, takes place the formation of light molecular weight or microcristalline cellulose, glucose or organic acids, methanol and furfuralic compounds.

Description

 Process for the delignification and saccharification of vegetable lignocellulosic materials using organic solvents

The invention relates to a new acid-catalysed hydrolysis process for the rapid dissolution of lignin and hemicellulose from forest and agricultural materials and the production of cellulose fiber material or its conversion products, lignin and sugars or their conversion products.

The invention relates in particular to the reduction in the time required for separating the cellulose fiber from lignocellulose and the recovery of the fiber in a high degree of polymerization, for which purpose a new solvent mixture, which consists of water and a liquid organic solvent, catalyzed by an acidic additive , which adjusts the solvent to pH in the range of 3.5 to 1.7.

For the implementation of the method according to the invention, a cooking liquid of water and an organic solvent, which contains an acid catalyst, is used, with which the lignin contained in the lignocellulose at elevated temperatures in the range from 160 to 210 ° C. rapidly and without the formation of derivatives is dissolved out and hemicellulose is hydrolyzed, so that the lignocellulose is converted within a few minutes to a pulp from a dispersion of cellulose fibers in a solution of lignin and sugars. Such pulps have a low lignin content and are well suited for paper production or for solution / regeneration processes or as feed for ruminants. Alternatively, the lignin-free residue of the lignocellulose can be further hydrolyzed by boiling for a long time in the same solvent mixture, whereby a powder of low degree of polymerization or. Sugar or dehydration and degradation products of sugar such as furfural and organic acids can be obtained. The lignin and sugar obtained can be used as raw materials in the phenol, sugar and sugar fermentation industry. Wood consists of about 40 to 50% by weight of cellulosic polymer in the form of a powder, namely a polymer of β-anhydroglucoside units, about 15 to 20% by weight of hemicellulose, which consists of mannose, xylose and other hexose and pentose sugars and uronic acids, and about 20 to about 30 wt .-% lignin, which consists of a number of lignin substances from phenolic structural units in polymeric form. Waxes, rubbers and masked mineral compounds can be present in different quantities as further components.

The aim of the wood recycling process is to separate its components as cleanly as possible and with the least possible degradation of the components or the sub-component of a component, i.e. to win every component in. natural form. The processes for separating the cellulose fiber require the removal of as large a portion of the lignin as possible so that the fibers are dispersed into a pulp, a fiber with high binding capacity is obtained and as little bleaching as possible is required. The usability of cellulose as animal feed is greatly improved if the residual lignin content is reduced to below 5.3. Since the lignins and hemicellulose surround the crystalline cellulose fibers as the layers forming the cell walls, the removal of these amorphous, relatively porous substances by chemical attack was the basis of most known separation processes.

The question of how lignin, hemicellulose and cellulose polymer are linked is still largely unsolved today. However, there is some evidence that there is some binding between a small proportion of the lignin and a proportion of the hemicellulose. Chemical separation processes have been developed with a great deal of work, but all of them involve modification or degradation of lignin and hemicellulose, which occur at high temperatures temperature and high acidity or alkalinity are quickly attacked. The crystalline cellulose is also broken down considerably, in particular by breaking the polymer chains at the disordered crystal sites. The fibers separated according to the known acid-catalyzed processes still contain undissolved lignin and hemicellulose, so that further treatments with alkaline solutions and / or bleaching agents are required, by means of which the cellulose is further degraded.

The article "Ä Review of Lesser-Known Pulping Methods" by C.J. provides a historical overview of a large number of known processes for producing chemical pulps using organic solvents and various catalysts. Brounstein, Pulp and Paper Magazine of Canada, January 1952. Other publications on the use of mixtures of organic solvents for the production of pulps are US Pat. Nos. 3,585,104 (1971), 2,959,900 (i960) and 4,003702 (1977).

The invention is an improvement on the known processes using organic solvents to release the cellulose fiber and consists in an optimal combination of liquid organic solvent in a mixture with water, which is able to penetrate excellently into hemicellulose and lignin and to contribute the acidic catalytic compound contained in it so that the acidic mixture of lignin and hemicellulose can rapidly hydrolyze and dissolve the hydrolysis products releasing a high strength cellulose fiber. It has been found that a mixture of a liquid, volatile, water-soluble organic solvent with a solubility parameter in the range of 10 to 13, which is either a low molecular weight aliphatic alcohol or a low molecular weight aliphatic ketone, with water in a ratio between 0.43 and 2.33, that acidified to a pH in the range from 3.5 to 1.7 by the addition of a certain hydrolysis catalyst, rapidly penetrates into lignocellulose and. degrades lignin and hemicellulose to their monomers at elevated temperature without significantly reducing the degree of polymerization of the cellulose fiber. Bulk delignification and saccharification can be accomplished to any desired degree by increasing the cooking time, which can be as low as 5 minutes to free aspen fibers, or up to 1 hour or less to wood a solids residue of only 1%.

Hardwoods, softwoods, and agricultural lignocellulosic material such as straw, bagasse, grass, and bamboo are rapidly converted to dispersions of fibrous material in a liquid containing sugar and lignin when dissolved at about 180 to 200 ° C with, for example, ethanol or acetone as the organic solvents and hydrochloric acid or oxalic acid as the acidic catalyzing compound dissolved in the solvent mixture. As described in more detail below, however, other solvents and acid catalysts according to the invention can also be used to separate the cellulose fibers.

The main object of the invention is therefore a cooking liquid with which cellulose fibers can be separated extremely quickly in a relatively undegraded state.

Another object is to provide a new hydrolyzing solvent mixture containing an acid catalyst which is inexpensive and. for a process in individual batches or a continuous separation of fibers and their dispersion into a pulp in a solution from which lignin and sugar of high purity can be obtained.

⁺ low molecular weights or Another object of the invention is a cooking liquid which can be used either to separate cellulose fibers or to saccharify lignocellulose to a desired degree, including virtually complete dissolution of the wood.

In the drawings are:

Figure 1 is a schematic representation that shows which products are obtained by the process when lignocellulose is treated for different lengths; and

Figures 2A, 2B and 2C are schematic representations of an apparatus for performing the method with which the products of Figure 1 are obtained.

Solvent mixtures and their effects on

Components of lignocellulose

As is known, the accessibility of the cellulose in lignocellulose to the cooking liquid initially depends on the ability of the solvents to swell and dissolve the lignin, in particular the high molecular weight lignins present in the cell wall layers. It is also known that the swelling and dissolving power of solvents for lignin increases as their hydrogen bonding capacity increases and their solubility parameters, which indicate the cohesive energy density of the solvent, approach a value between 10 and 13. The meaning of this parameter results, for example, from "Solubility of Non-Electrolytes" by JH Hildebrand and RL Scott, 1951, Edition III, Reinhold Publishing Company, New York, in particular Chapter X. The lignin solubility becomes in the article by CH. Cshuer, "Solvent Properties of Lignin and Their Relation to Solubility, Swelling, Isolation and Production of 'Lignin", Ind. & Eng. Chem. Vol. 74, pp. 5061-5067.

It has been found that a shift in the oxygen / deuterium (OD) wavelength in the infrared region of the -OH bond when a hydrogen bonding solvent is mixed with heavy methanol (CE ₃ OD) is proportional to the hydrogen bonding ability of the solvent. A shift of 0.14 units has been found to be optimal for the best insolubility in lignin. Values below this value indicate moderate or poor lignin solvents. As can be seen from Table I, which lists the solubility parameters and deuterium shifts for some organic liquid solvents, the solubility of lignin is limited to solvents with a solubility parameter in a narrow range of generally between about 10 and 13 units, which are arbitrary numerical values are assigned to the vapor pressure measurements and correspond to an optimal infrared shift for -OH-OD of 0.14.

Table

Solubility-deuterium solubility of the medium parameter shift originally present lignin

Ether 7.5 0.19 insoluble

Methyl ethyl ketone 9.3 0.11 partially soluble

Dioxane 10.0 0.14 soluble

Acetone 10.0 0.14 soluble

Pyridine 10.7 0.27 soluble

MethylCellusolve 10.8 soluble over 0.4

Ethanol 12.7 soluble over 0.4

Ethylene glycol 14.2 0.31 soluble

Glycerin 16.5 over 0.4 insoluble

Water 23.4 over 0.4 insoluble

As is known, water has a limited solvency for certain lignins and is able to dissolve primarily monomer units of a polar nature. Medium to low molecular weight lignins are capable of dissolving in the low molecular weight aliphatic alcohols, while dioxane, acetone and pyridine have proven to be excellent solvents for all molecular sizes present in lignin preparations obtained by mild extraction methods.

It has now been found that the solubility of natural polymeric lignin in a mixture of a hydroxylated solvent such as water or the low molecular weight aliphatic alcohols with a good lignin solvent such as dioxane, acetone, ethanol or pyridine is larger than in the pure liquid solvent alone. This effect is particularly strong in mixtures containing water and ethanol or M-oxane, but most impressively in mixtures of acetone and water which, when the constituents are present in almost equal amounts, penetrate lignocellulose extremely quickly.

It has also been found that the improved lignin solubility of the solvent in admixture with water can be related to the improved hydrogen bonding capacity of the mixture over either pure water or pure liquid solvent. The improved hydrogen binding capacity results from the phenomenon of the volume reduction of a mixture of the same volume of ethanol or acetone and water and in particular from the strong development of air bubbles and the turbidity of a mixture of ethanol or acetone with acidified water which contains gases dissolved in the air. The volume shrinkage when mixing equal volumes of acetone and water is about 4%, for equal volumes of ethanol and water 2%, which indicates different cohesive energy densities.

Effective hydrolysis of lignocellulose is achieved when the mixing ratio of organic liquid solvent to water is in the range of about 30 to 70 parts of solvent to 70 to 30 parts of water. Since the simultaneously hydrolyzed sugars and lignins must be taken up by the common solvent mixture during a cooking operation, the solvent mixture must be used in excess - usually in an amount of 4 to 12 times the weight of the wood - and also a sufficient amount of water , especially during the later stages of cooking, during which the carbohydrate is on solubility of the solution will be critical to solubilize the sugars that are largely insoluble in the organic solvent. If the fiber separation is carried out in two successive stages in which different solvent mixtures are used, higher ratios of organic solvent to water are generally advantageous for the solvent used first in order to take up the lignins, during the later stage when the hydrolysis limited to the dissolution of residual hemicellulose and glucan, lower ratios of liquid solvent to water are preferred to accommodate the higher concentrations of hydrolyzed sugars.

The solvent mixture also has a significant influence on the adjustment of the ionic strength and the dissociation of the acid catalyst dissolved in the mixture. For example, different hydrolyzability can result if an aqueous amphiprotic solvent of water and ethanol or an aqueous aprotic solvent mixture, such as water and acetone, is mixed with the same amounts of a particular acid catalyst. Such a difference can be used to advantage in such a way that the rate of hydrolysis is accelerated during the initial boiling, while at the end of a boiling process the least possible impact on the cellulose is desired, so that undegraded fibers of high purity are released from the solvent mixture become.

Properties of acidified cooking liquids

Solvent mixtures of water and an organic solvent, such as acetone, ethanol or dioxane, which contain an acidic compound in solution and have a pH of only 1.7, make this possible hydrolysis proceed through all impregnated zones of the lignocellulose structure. The combined presence of protons from the dissociated acid and liquid solvent favors the penetration of the cell wall layers and differential sources of the components, so that soluble hydrolysis products, which are quickly absorbed by the liquid, are formed. Although all acids can of course be proton donors, it has been found that different acids, when dissolved in the aqueous solvent mixture, have different fiber separation properties. For example, some acids have practically no fiber separation capacity even at a temperature above 200 ° C., while other acids have very different effects, so that only a relatively small number of acids have proven to be practically usable.

Mild hydrolyzation catalysts are generally suitable for the production of pulps for paper production, while a cellulose of high purity, albeit with a lower degree of polymerization - hereinafter referred to as "DP" - is best obtained using strong acids in the solvent mixture, where strong acids are then required if complete wood saccharification is to be achieved. It could have been expected that strong acids with high dissociation constants, i.e. close to uniformity, faster and more potent hydrolyzing agents than complex acids and organic acids with low dissociation constants. However, the acidified solvent mixtures do not meet these expectations.

Acidity is a macroscopic property that indicates the ability of the solution to make protons available for reaction with a base or for the termination of a transfer process, and is based on measurements based on conventional singles ionic activities are based, such as determinations of pH, dissociation constants and pK values. The acidity is most accurately represented by the single electrode potentials.

The ionic strength usually results fairly accurately from the entropy of ionization, which is different for different acids, mainly due to the action of the anions present in mixtures of solvents and solutes. When considering ion balance and reactivity in a solution, the effects of the solvent in question must be taken into account because the interactions between solvent and ions modify the mobility of the ions, the ion potential and the kinetic energy of the ions.

The electrostatic hydrogen binding capacity of solvents and their self-dissociation are usually considered to be the cause of changes in the ionization constants of acids in solution. For example, the dielectric constant of a solvent modifies the activity coefficient of dissolved charged particles. When a neutral acid is dissolved in an aqueous / organic solvent mixture, lowering the dielectric constant of the solvent lowers the activity coefficients of the protons and the solvated anions, which also lowers the ionization constant of the acid. However, there were significant differences from the expected changes in ionization constant both in aqueous amphiprotic solvents such as ethanol / water which are characterized by hydrogen bonding and in aqueous aprotic solvents such as acetone / water which are characterized by the absence of hydrogen bonding , detected. It was found that the ionic conductivities for the acids were very irregular with a change in the Solvents vary, indicating that there is no direct relationship between the conductivity and dielectric constant of the solvent, or the fluidity or association tendencies of the solvents.

When aqueous-alcoholic solutions containing 50% or more of ethanol were mixed with different acids, the acid dissociation was very different, even if the solutions had constant concentrations of the acids in question. In contrast, the conductivities of water / acid mixtures were almost the same. The anomalies were greatest for weak acids as strong acids are leveled, i.e. be converted into the acidic species in aqueous solutions. As is well known, weak acids do not fully dissociate, and the acidic property of the organic solvent itself, i.e. its hydrogen binding capacity determines which protolytic reaction takes place between the solute and the solvent. Because of the unequal solvation of different anions, the relative strength of acids in solvent mixtures largely depends on the chosen organic solvent.

Amphiprotic solvents have good proton stability because free protons are scarcely available because of their combination with some solute / solvent species that have the same character in such solvents. Variations in proton acceptor / donor capacities of amphiprotic solvents depend on the acid strength and base strength of the solvent itself, so that when two amphiprotic solvents have the same autoprotolytic constants, namely dissociation or ion product constants, very different effects on the acid behavior of such solvents can be observed . This arises from the fact that the interactions between ions and solvents are usually stronger than the interactions between the uncharged particles, causing solvation of the acid anions in question to become unequal in the various solvent systems. Since different acid / base equilibria are established, the acid strengths depend on the type of solvent system. These effects can be taken into account if an acidic additive is selected for a solvent mixture of the desired hydrolyzing capacity, for example if the hydrolyzing capacity is to be sufficient to break down hemicellulose to sugars but not to attack the glucan.

The experimental selection of an acid for a solvent mixture, which should have a certain hydrolyzability, must first consider its dissociation constant or its pK _A value in water. However, this does not result in its catalytic effect with regard to the release of the fiber with certainty, since weak acids with the same charge type and almost the same dissociation constants not only behave differently in a certain aqueous / organic solvent mixture of constant composition, but also change their behavior when an aprotic Solvents such as acetone instead of an araphiprotic. Solvent such as ethanol is used. It was found through experiments that at the same concentrations of solvent / water / acid acetone the dissociation was reduced by 25% more than when ethanol was used as the organic liquid solvent. The effect was most pronounced at high acetone concentrations in the mixture. Acetone is not a hydrogen bond donor, so the chemical behavior of anionic dissolved particles is different from that usually observed in hydroxylic solvents. Since the ionic strength of acids is influenced differently by the proton release of the acids and the solvolysis of the anions in these solvents, measurements of the potential of the hydrogen electrode must be carried out in such a way that the average effect on the hydrogen ion is measured as a rough measure, although it is certain that that the hydrogen electrode potential and the stability depend considerably on the solvent system. The pH and conductivity values compiled in Table II illustrate the above relationships.

The values show that high solvent / water ratios that favor the solubilization of lignin, lower conductivities for both strong acids such as HCl and weak acids such as oxalic acid at 60:40 ratios for both ethanol / water and for acetone / water mixtures compared to acid / water mixtures of the same molarity.

In general, it should be noted that with dicarboxylic acids in which the -COOH groups are closer to one another, the effect of adding alcohol on the pK _A value is greater for the first dissociation than for the second. This effect is less pronounced for acids in which the -COOH groups are further apart. The activity factor is less affected by the addition of alcohol for undissociated molecules than for the lyonium ions.

If solvent mixtures are mixed with acids which must be present in a molarity above 0.025 to 0.05 in order for the pH to be adjusted to 2.5 or below, the effect of the mixture on the separation of cellulose fiber from lignocellulose is moderate, because of this Acids require long cooking times and / or high acid concentrations and thus high energy consumption and lead to extreme depolymerization of the cellulose. In Table III, for a number of organic mono- and dicarboxylic acids, the anti-signifying ability at a molar concentration of 0.05 in an ethanol / water mixture 60:40 at 200 ° C., the associated kappa values and the residual lignin content on the fibers , the degree of fiber separation and the TAPPI viscosity, which characterizes the degree of polymerization of the fiber. Spruce lignocellulose with a chlorite holocellulose content of 77.5% was used. It turns out that if the fibers were not separated at 30 minutes, the pH of the cook was insufficient liquid was generally a determining factor, although there are exceptions for the case of monochloroacid and trichloroacetic acid.

Fiber separation and saccharification of lignocellulose using acid-catalyzed aqueous / organic solvent mixtures

Lignocellulose impregnated with the hot, aqueous, acidified organic solvent mixtures according to the invention are currently subject to delignification and saccharification by the solvent mixture, so that the constituents are progressively separated from one another. Initially, the geraic only penetrates and hydrolyzes the easily accessible hemicellulose and lignin, and the dissolved hemicellulose sugar and lignin are fed into the main part of the mixture, from where they can be removed by withdrawing the liquid to avoid decomposition and theirs To enable extraction in a very pure state.

Shortly after the onset of solubility, if an aggressive acid catalyst is used, a disorderly hydrolysis of the glucan, which begins at the accessible locations of the cellulose fibers, which are exposed by the removal of hemicellulose, progresses to the microfibers and crystallites and at the appropriate time, the cellulose depolymerized to a low DP. The strong acids - hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid - at molar concentrations below 0.05 as acidic catalyzing compounds in the solvent mixture have the ability to lower the DP value so quickly that at the time when cooking caused mechanical Fiber separation, for example by refining or grinding the lignocellulose residue, has been made possible, the DP value has already been greatly reduced.

If boiling continues, the hydrolyzing action of the solvent scent will make the crystallites depolymerized further until a virtually complete dissolution of the cellulose network is achieved. To illustrate this, two batches of wood chips, one from oven-dried aspen, the other from Douglas fir, with initial DP values of 1160 and 1120, were three minutes in a 50:50 aqueous acetone solution with a molarity of HCL of 0 , 02, ie a concentration of 0.07%, cooked at 200 ° C. The initial pH was 2.8. The cellulose residue had a DP value of about 120 and contained only a very small amount of residual lignin. Such a DP value corresponds approximately to cellulose crystallite lengths in the starting cellulose of 60 nm (600 Å). With further boiling of the dissolved material and the residue, the DP value did not change significantly until all of the solids were hydrolyzed.

The effect of the other strong acids in such amounts that the pH of the solvent mixture was not above 3.5 and preferably 2.5 or less largely corresponds to the stated effect of HCl. If a selective dissolution of hemicellulose and lignin with little or no hydrolysis of the glucan is desired, a suitable water-soluble, volatile organic solvent, such as methanol, ethanol, i- or, is expedient in order to obtain pulps with superior DP values of high quality nPropanol, butanol, acetone, methyl ethyl ketone, dioxane or pyridine, and a weak acid such as maleic, oxalic, L-apple, succinic, o-phthalic, nicotinic or trifluoroacetic acid, in a molar concentration between 0.025 and 0 , 05 used. Alternatively, one of the strong acids, buffered by admixing a neutral salt of the acid so that the pH of the solvent mixture is adjusted to about 2.2 or below, can be introduced into the aqueous-organic solvent mixture, so that a separation of cellulose fibers with high DP Values can be achieved. The lignin released from the solvent mixture can be obtained in the uncontaminated state by separating it from the mother liquor by distilling off the volatile component. It is obtained in a sugar-free state in such a form that it can be dissolved in the usual organic solvents, such as acetone, ethanol, dioxane, pyridine, DMSO, methyl cellosolve and tetrahydrofuran.

The dissolved carbohydrates, which are in monomeric form, can easily be separated from the remaining liquid and can be worked up further, for example by fermentation, dehydration, reduction, hydrogenation, etc. The saccharification effect of the solvent mixture on the glucan has been found to follow first order kinetics, i.e. gives about 5 to 10% glucose yield per minute cooking time at 200 ° C.

In the following examples, which describe certain cooking methods, the influence of time and temperature on the product recovery is examined. The preferred temperature and time parameters chosen, to which the various processes are adjusted according to the desired products, follow general guidelines for the hydrolysis of lignocellulose components, i.e. : Approximate end point for hemicellulose extraction: boil for 3 to 5 minutes at 165 to 180 ° C with mild acid or a mixture of acid / salt;

Products: lignin solution, low lignin pulp, hemicellulose sugar; Approximate end point for obtaining a high quality pulp:

Cooking time 5 minutes more at 200 ° C with mild acid or a mixture of acid / salt;

Products: best quality fiber pulp, lignin solution, xylose or mannose sugar, reducing sugar;

ITÜREALT

O-MPI Approximate end point for microcrystalline residue:

Cooking time 5 minutes longer at 200 ° C with strong acid;

Products: pulp with high lignin content and low DP, lignin solution, reducing sugars; Approximate end point for total saccharification:

Cooking time 4 to 10 minutes longer at 200 ° C with strong acid;

Products: solid residue, furfural or hydroxymethylfurfural, organic acids, methanol.

Reference can be made to FIG. 1, which illustrates the progressive decomposition of lignocellulose and the ways in which products of special process variants are obtained.

Example I In this example and the associated Table IV, the dissolving power for the constituents of cellulose from acidified aqueous-organic solvents is compared. In particular, ethanol / water / acid mixtures and acetone / water / acid mixtures are compared in terms of their effects on 100 g aspen or Douglas fir schnitzel. Each 100 g of this schnitzel was introduced together with 1200 ml cooking liquid from water and organic solvent 50:50 into a test cellulose cooker, two batches being impregnated with an acetone-containing mixture and the other two with an ethanol-containing mixture. All liquids contained 0.07% by weight HCl as a hydrolyzing catalyst. The acid had been added to an appropriate amount of water before the organic solvent was mixed in, and the volume contraction on mixing was balanced with 50:50 aqueous solvent to adjust the desired acid concentration. Samples were taken from the contents of the cooker at the times indicated without reducing the pressure in the container, and these samples were analyzed. TABLE IV

Temperature time solution type of wood

° C min. medium Esoe Douglas fir

Yield residual yield residual pulp lignin on pulp lignin%%%%

7 47.9 2.4 47.5 7

10 45.4 1.8 42.0 5.85

200 ethanol 20 31.2 0.5 31.5 2.1

30 28.6 - 26.8 -

7 43.5 1.0 34.1 2.13

10 34.2 0.35 22.5 1.30

200 15 acetone 15.1 - 12.3 0.75

20 1.0.4 - 6.5 -

30 3.7 - 2.03 -

The values in the table show the superior dissolving power of the mixture of water, acetone and HCl, since the complete flushing of Douglas fir, a type of wood that is difficult to process, required only 20 minutes. If ethanol is used as the organic solvent in the cooking liquid, yields of pulp of not less than 24% are obtained even if the cooking time is extended to 60 minutes. Cooking times shown in the table include an initial interval of 5 minutes during which impregnation and limited hydrolysis began while the feeder was heated to process temperature in a glycerol bath kept at 200 ° C. Example II The influence of the acid concentration and the attack of the acid were compared at a constant temperature of 200 ° C. only for aspen wood within a limited range of the water to solvent ratios. All HCl cooking procedures were carried out with a solvent mixture of water and acetone using a wood: liquid weight ratio of 1:10; all oxalic acid cooking was carried out with 0.5m acid and a solvent mixture of water and ethanol with a ratio of wood: liquid of 1:10. The HCl / KCl acid / salt mixture was 0.0692m KCl and 0.0108m HCl in a 60:40 by volume mixture of ethanol and water, and the wood: liquid ratio was 1: 8. The indicated pulp yields are to be understood as% by weight of the feed. Amounts of sugar and lignin are to be understood as percent of the ultimate yield achieved by the hydrolysis process used. The whole wood contained a total of 19% separable lignin, a total of 74% separable holocellulose, 56.3% separable cellulose and 17.9% separable hemicellulose consisting of 1.9% mannose and 16.0% xylose. The values given show that an increase in the acid concentration from 0.01 m to 0.02 m when using HCl has little or no effect on the reaction rate constant at constant reaction temperature and somewhat different ratios of organic solvent: water. However, when the concentration tripled - from 0.02m to 0.06m, there was a significant effect, and% the influence of increasing the acid concentration at the higher concentrations is comparable to that of increasing the temperature on the rate of hydrolysis.

The superior yield of pulp obtained with a buffered mixture of strong acid and salt and the high value of dissolved lignin make it possible to obtain a high-strength paser from plant materials of all kinds, as will be shown next.

The tear length of the cellulose pulp is strongly dependent on the residual viscosity, i.e. affects the degree of polymerization of cellulose after isolation of the fiber. Strong acids, even at low concentrations, are not specific in their hydrolysis activity in that they hydrolyze, i.e., link all glycosidic linkages in lignocellulose, including those found in high order areas. Hydrolyze amorphous, mesomorphic and crystalline cellulose.

It has now been found that when using a less aggressive catalytic acidic compound, in particular a weak organic acid, namely an acid with a dissociation constant below that of the strong acids, namely maleic, L-apple, oxalic, amber, o- Phthalic, nicotinic, salicylic and trifluoroacetic acid, or when using a strong acid in a mixture with a neutral buffer salt of this acid, a delignification effect of the aqueous-organic solvent solvent is achieved, which is almost as fast as with the mixture of strong acid and Solvent is possible, but releases a cellulose fiber with a considerably improved DP value.

A very much higher DP value of the cellulose fiber can be achieved by using shorter delignification times if an aqueous-organic solvent mixture catalyzed with oxalic acid is used. DP values of the released fiber were found to be close to those of practically undegraded natural fiber. Example III

A number of shredded, oven-dried aspen and spruce wood batches of 5 g each were boiled in a high-pressure stainless steel cooker with 60 ml of a mixture of water and ethanol 40:60. Certain amounts of HCl, oxalic acid, or buffered HCl / KCl were added to each feed. The acid / salt mixture contained 0.0692m KCl and 0.0108m HCl in the ethanol / water mixture 60:40 by volume so that the impregnation mixture had a pH of 2.2. Yields and DP values of the remaining cellulose are summarized in table VT. The degree of polymerization was determined by the method of using an iron / tartaric acid / sodium complex. The wood: liquid ratio was 1:12 when using aspen wood and 1: 8 when using spruce wood, except for cooking spruce wood with HCl, where a wood: liquid ratio of 1:10 was used.

T a b e l l e VI

Temp. Time acidity and types of wood

° C min concentration, aspen spruce molar

FromRestAusRestbue lignin DP lootin 'DP on

Pulp Pulp%%%%

Starting timber: 77.36 ¹ 0.67 1140 11, 50 1.3 1220

5 HCl, 0.02 46.9 1.0 120 47.8 5.24 187

200 5 OXA, 0.05 53.2 4.9 980 50.9 6.42 640

10 OXA, 0.05 51.2 3.5 700 - - -

25 OXA, 0.05 - - - 49.2 4.5 630

5 OXA, 0.025 59.4 5.8 1125 - - -

200 10 OXA, 0.025 52.9 4.0 1025 67 15.6 987

15 OXA, 0.025 51.9 2.31 870 65 14.3 675

200 3 HCl / KCl 65.6 6.2 465 - - - 7 HCl / KCl 56.8 4.8 450 50.9 6.09 440 OXA = oxalic acid = values for chloritol holocellulose These values show the extraordinary improvement in the strength of vegetable fibers of all kinds compared to those which have been obtained up to now by chemical or bacterial / fungus action. The strength of paper webs, laminates, filters, yarns, ropes and cordage from all fiber-containing plants can obviously be significantly improved by using the method according to the invention to release such fibers.

The semi-mechanical or semi-chemical pulps are a compromise between the high yields of mechanical pulps, e.g. wood pulp, and the very firm chemical pulps, in that a better pulp with less damaged fibers can be obtained if part of the material connecting the fibers, namely the Lignins and the hemicelluloses, removed and the fiber network is softened by chemical action so far that only low tensile forces are required to loosen the fiber groups.

Such an improved pulp is obtained in a lower yield, but with a higher sheet strength and in a much shorter time than is required to produce a pulp by chemical action alone. The process of the present invention can be easily carried out for the production of very high strength webs at low cost and in a short time, cooking either in single batches or continuously, or either in only one step or in two steps using a mixed solvent of either Water and ethanol and water and acetone and a weak acid or a buffered strong acid can be carried out as a catalyst.

The delignification and hydrolysis of, for example, shredded wood, straw, sugar cane or bagasse can be used in one Pulp boiler temperature of about 180 ° C usually take only 3 to 5 minutes. At this point, the lignocellulose residue has softened but still retains its initial structural shape when the material is stirred in a liquid and can still be easily processed into a fiber dispersion, i.e. a pulp, by passing it through one or more high pressure grinders, in which he is subjected to high liquid shear forces, so that a thermomechanical pulp is formed. Lignin contents of 5 to 6% can be achieved and a pulp with extremely high strength is obtained.

The cooking liquid or liquids can be processed further in the manner described below in order to obtain organic solvent and other dissolved materials.

For example, to dissolve pulp for the production of regenerated cellulose, a DP value for bleached pulp of over 800 and a minimum content of α-cellulose of 85% or above is required. According to the present invention, these requirements are met, as described in more detail below.

Example IV

A number of batches of air-dried flakes of aspen, spruce and birch wood, each weighing 20 g, with flake dimensions of approximately

2 cm × 6 cm × 0.8 mra - 1.5 mm, sugar cane fibers of 3 mm ×

3 mm × 10 cm and wheat straw of 10 cm in length, also 20 g, were carried out. Each charge was introduced into a stainless steel bomb cooker with a solvent mixture such that the weight ratio of charge to solvent mixture was 1:10. The solvent mixture consisted of 60 parts of ethanol and 40 parts of water and contained so much oxalic acid that its concentration was 0.05ra. The temperature of the cooker was within brought to 200 ° C for about 7 minutes, and cooking was done at that temperature for a certain time. The pulps obtained were analyzed for yield, residual lignin, DP and α-cellulose. The values obtained are shown in Table VTI.

The above values show that all pulps obtained in this way had an α-cellulose content of over 85%. All of these pulps responded exceptionally well to a three step bleaching sequence of chlorination, extraction hypochlorite, after which the whiteness of that of bleached pulps, i.e. 88%, was quite comparable. The cellulose contents were in the range from 95 to 99%.

Example V

The removal of the major part of the lignin from lignocellulose, such as straw, grass, sugar cane residues and various hard and soft woods, has also been used to improve the digestibility of such materials by ruminants. However, the cost of delignification has so far been so high that a such material could not compete with the usual animal feed. In addition, in some known methods of delignification, the residual lignin is changed so that the lignocellulose residue is toxic to cattle.

The present invention largely reduces the cost of delignification, and a residual lignin content of less than 5% is obtained in a short cooking time. A number of experiments were carried out with 100 g of air-dried aspen, Douglas fir, spruce, bagasse and wheat straw. Each feed was placed in a stainless steel pulp cooker along with a 60:40 solvent mixture of acetone and water that was 0.02m hydrochloric acid. The cooking temperature was 195 ° C after a heating time of 6 to 7 minutes and different cooking times were used. Yields, residual lignin contents and digestibility are summarized in Table VIII.

T a b e l l e VIII

Species Cooking time Yield Residual digestibility min. % dry material lignin,%

Aspen 7 40 0.39 91.3 8 36 0.14 92.5

Douglas- 7 40 3.43 75.4 Fir 8 30 2.73 84.8

Spruce 7 45 5.00 74.0 8 37 3.6 74.4

Bagasse 5 64 5.7 56.4 7 50 3.5 67.1

Wheat straw 7 64 3.6 78.6 15 55 2.8 89.1 The indicated digestibility was determined in vitro by the method of RW Mellengerger et al, 1970, J. Anim. Be. 30: 1005-1011. Each pulp was ground to a particle size of 0.8 mm (to pass 20 mesh screen) and the powder was incubated with rumen fluid from slaughtered cattle.

The above values show that it is possible according to the method according to the invention to produce an excellent cattle feed from plant material which has hitherto been difficult or impossible to use. By extracting by-products from the cooking liquid, such as lignin, sugars, and recycled solvent, the costs of carrying out the process and the installation required for this are reduced. The device used can be a one-step cooker, an open trough being used for the impregnation with the solvent mixture at room temperature. The system consists of a pressurized feeding device for the wood particles, a gate that can withstand a pressure of 35 dar, a heating system, a high-pressure heating and injection system for liquids, return lines, a cooling and washing device on the bottom, a centrifuge with a flushing device , a simple flash evaporator for solvent recovery, a mixer for the feed and a pelletizer for the pulp.

Example VI

Some organic acids, which promote fiber separation in a mixture with aqueous-organic solvent mixtures, have particular advantages if the aim of the hydrolysis is to dissolve hemicellulose and lignin, but to obtain a high DP of the fiber by gradually decomposing at the cooking temperature, which limits their action to the glucan. For example, oxalic acid decomposes to CO ₂ and at the higher cooking temperatures H ₂ O and salicylic acid to phenol. and CO ₂ , so that the initially rapid hydrolysis with the 0.05 m catalyst at the beginning of the boiling results in an early release of the fiber by the solvent mixture thus catalyzed. enables while the hydrolysis effect, when the cellulose is exposed, is milder.

A series of experiments without lignocellulose with oxalic acid as catalyst in an ethanol / water mixture of 60:40 and an acid concentration of 0.05ra was carried out by boiling at 200 ° C. The pH was measured from time to time over a 30 minute period and samples were taken to titrate the liquid and measure the residual acid. Another series of experiments was carried out using a liquid containing no organic solvent, and in another series of experiments equal parts of acetone and water were used. The values compiled in Table IX show a progressive and rapid decrease in the acidity of the solvent system with the tent, this decrease being greatest with ethanol / water and the lowest with water alone.

Die praktische Anwendbarkeit dieses Phänomens wurde durch eine Versuchsreihe, bei der Espen-, Fichten- und Birkenholzflocken bei 200ºC in einem Losungsmittelgemisch Äthanol/Wasser 60:40, .angesäuert durch Zugabe von Oxalsäure auf eine Säurekonzentration von 0,05m gekocht wurden, studiert. In Tabelle X sind die Ausbeuten an Pulpe, Restlignin und DP der Faser zusammengestellt.

The practical applicability of this phenomenon was studied by a series of experiments in which aspen, spruce and birchwood flakes were boiled at 200 ° C in a 60:40 ethanol / water solvent mixture acidified by adding oxalic acid to an acid concentration of 0.05 m. Table X shows the yields of pulp, residual lignin and DP of the fiber.

T ab e l l e X

Species Cooking time Yield Residual lignin DP Initial min. on pulp Kappa number / TAPPI concentration% viscosity oxalic acid

8 62.3 58 / 7.54 1250 0.025m

Espe 10 59.63 52 / 6.85 1200 0.025m 15 51 39 / 5.19 1180 0.025m

10 67 120 / 15.6 987 0.05 m

15 65 110 / 14.3 0.05 m

Spruce 20 57.3 95 / 12.3 950 0.05 m

30 56 97 / 12.6 - 0.05m

10 63.2 35 / 4.55 1360 0.05m

Birch 15 60.8 25 / 3.25 1320 0.05 m

20 57 27 / 3.51 1170 0.05 m

The rate of loss of wood substance is about 2.5% for every 5 minutes of cooking time extension after an initial heating-up time of about 7 minutes. The fiber is released in aspen in a cooking time of 7.5 minutes and in spruce in a cooking time in 8.5 to 9 minutes. The low cooking losses indicate that the decomposition of the acid favors the maintenance of high fiber DP values. If the pulp cooker is a container in which inlet and outlet openings are arranged at a large distance from one another at opposite ends of the container and is equipped with means for moving the lignocellulose and the solvent mixture, the relative movement between flowing liquid and progressive lignocellulose can be chosen in this way that the yield and production of the products as well as the fiber quality are optimal. The decision as to whether liquid and solids are conducted in parallel or in countercurrent depends on the goal of cooking. In general, the delignification effect of cooking is greatest when the highest acid concentration is present at the start of cooking. The hydrolyzing capacity is greatest by running the solvent mixture and lignocellulose in parallel. If, however, temperature-sensitive hemicellulose sugars are to be obtained in the highest possible purity, the residence time of the liquid must be as short as possible in order to avoid acid-catalyzed thermal conversion of xylose and mannose, so that in this case the countercurrent flow is preferred. If temperature-sensitive organic catalysts such as oxalic acid and salicylic acid are added to the solvent mixture, the countercurrent flow must be used in order to avoid premature deterioration in the hydrolyzability of the solvent mixture. This is taken into account when using a system according to FIGS. 2A, B and C, which can be used to extract the entire range of products that can be obtained from lignocellulose, as illustrated by FIG. 1.

According to FIGS. 2A, 2B and 2C, lignocellulose chips are continuously thrown from the conveyor belt 1 as a feed onto a screw 2 and are fed through this to a high-pressure screw 3 of a pre-impregnation device 5 at a certain speed. The cutlets that arrive at the end of the snail are marked with a Solvent mixture, pumped by the pressure pump P and fed through inlet 4 at the inlet end of this device, preheated to a temperature above 100 ° C and preferably 150 ° C to initiate the impregnation.

The wetted chips are introduced into the first container 9 of a two-stage cooker 100 via the high-pressure screw conveyor 6. In the container 9, the chips are mixed and pretreated with a first, preheated cooking liquid which is fed through line 7 and storage tank 8 and the heating device 7A. This liquid is composed so that it can dissolve lignin and partially hydrolyze hemicellulose and can consist of 70 to 30 parts of acetone and 30 to 70 parts of water, preferably about 50 parts of solvent and 50 parts of water. Alternatively, the liquid may consist of ethanol and water in the same ratio and contains such an amount of catalyzing acidic compound, which may be oxalic acid, that it is present in the solvent mixture at a concentration of 0.025m to 0.05m and the mixture has a pH in the range of 3.5 to about 1.7, preferably about 2.2. The ratio of wood: liquid in the impregnation zone is kept between 1: 4 and 1:15, preferably around 1:10. The temperature of the liquid entering zone 9 is 180 ° C. or above, so that the temperature of the flakes or chips is rapidly increased and the dissolution of lignin and hemicellulose is initiated.

The liquid is kept in motion, either by letting it circulate between the inlet point and the filter ring 10 or by countercurrent. If the directions of flow are parallel, the solvent mixture exits through the filter ring 10 and flows back through line 11 and the heater 12 to the inlet of the container unless it is after a certain impregnation about the filter ring 10 and the line 13 is withdrawn and fed to the system 14, where there is a release evaporation of the volatile materials, after which they are passed through the condenser 15, where part of the vapors of the organic material is blown off through line 16, to then be collected in the condenser line 67.

The majority of the recovered first solvent mixture, which contains extracted lignin and extracted sugar and is therefore referred to as "used up", is collected in line 17 and fed to tank 18. At a pressure of 19 to 22 bar (280 to 320 psi) in the first pressure vessel 9, the residence time of the flakes or chips can be about 5 minutes and depends on the temperature, which can be in the range of 160 to 185 ° C or higher . Table XI shows analytical values of a lignocellulose residue which passes through the filter ring 10 and is acidified from 100 g of oven-dried wood with a first solvent mixture of acetone / water 50:50, with HCl in a concentration of 0.02 m or a concentration of 0.07% , was obtained.

Die im Behälter 9 teilgekochten Schnitzel werden durch den Filterring 10 geführt und treten unter der Wirkung einer konischen Beschickungsschnecke 20 in den zweiten Behälter 19 ein. Der Grad der Verjüngung der Beschickungsschnecke muß der Auflösungsgeschwindigkeit der Feststoffe, deren Volumen kontinuierlich sinkt, während sie sich durch diesen Behälter bewegen, angepaßt werden. Das zweite Losungsmittelgemisch wird über Leitung 21 und Vorerhitzer 22 von dem Tank 23 zugeführt und tritt mit einer Temperatur von 210°C in den Behälter 19 ein. Die Verweilzeit der in diesem Behälter fortschreitenden Schnitzel wird durch die Geschwindigkeit, mit der die Beschickungsschnecke angetrieben wird, gesteuert, und diese Steuerung ist das Hauptmittel, durch das das Verfahren dem gewünschten Produkt angepaßt wird, verbunden mit der Geschwindigkeit, mit der der feste Rückstand durch den zweiten Filterring 24 geführt wird. In diesem Abschnitt ist der Flüssigkeitsumlauf wesentlich, und die Bewegung des zweiten Lösungsmittelgemisches erfolgt parallel zu derjenigen der Feststoffe mit einer Geschwindigkeit, die etwas oder wesentlich größer als diejenige der Feststoffe ist.

The chips cooked in the container 9 are passed through the filter ring 10 and enter the second container 19 under the action of a conical feed screw 20. The degree of tapering of the feed screw must be matched to the rate of dissolution of the solids, the volume of which continuously decreases as they move through this container. The second solvent mixture is supplied via line 21 and preheater 22 from the tank 23 and enters the container 19 at a temperature of 210 ° C. The residence time of the chips progressing in this container is controlled by the speed at which the feed screw is driven, and this control is the main means by which the process is adapted to the desired product, combined with the speed at which the solid residue passes through the second filter ring 24 is guided. In this section, the liquid circulation is essential and the movement of the second solvent mixture takes place parallel to that of the solids at a speed which is somewhat or substantially greater than that of the solids.

After a certain contact time, the second solvent mixture is drawn off from the container 19 through the filter ring 24, the line 25 and the heater 2β, so that the cooking temperature can be exactly maintained. The pressure developing in container 19 using a 50:50 acetone / water solvent mixture containing 0.07% KCl and pH 2.2 is about 24 bar (480 psi). When the liquid is enriched in dissolved material or has reached its maximum residence time, it is drawn off through line 27 and the relaxation chamber 28, which is connected to a second condenser 29. The condensate is fed directly into the tank 31, while the steam is fed into the condenser line 67 via line 30. Under normal conditions in the second container under the conditions described for separation the fiber from the lignocellulose residue required about 2 minutes. Yields and products obtained for the use of aspen and Douglas fir are listed in Table XII.

T a b e l l e XII

Temp. Cooking wood temperature ° C time min. Espe Douglas -T-Anne

FestRestLignin Red. FestRestLignin Red. Lignin in LöZucker lignin in LöZucker statement sat. statement total loot loot%%%%%%%%

200 2 + 5 50.5 1.4 5.0s 10.5s. 47.5 3.5 46.0 11.0 = 7 sat.

These values indicate the percentage of the extracted component, based on the potentially extractable amount (see Table XI).

If the formation of dehydration products in the withdrawn liquid, which occurs when the dissolved sugars are exposed to a high temperature and a low pH for a prolonged period, is to be avoided, the liquid is quickly neutralized, for example with lime water, and stored in a tank until it is processed further. For further processing, organic solvents are evaporated off and the precipitated lignins are separated off by filtration / centrifugation. The aqueous solution can then either be stored with a preservative or, for example, up to a concentration of 20 to about 50% can be evaporated to a syrup.

In order to maintain the cooking temperatures, it may sometimes be necessary to supply heat from the outside in order to compensate for the heat consumed in the endothermic reactions, heat losses in the device, etc. Therefore, both containers of the cooker must be individually equipped with heating and control devices. The first stage must be kept at a lower temperature to avoid degradation of hemicellulose sugar, while the main cooking stage must be carried out at a higher temperature, especially if the process is to hydrolyze glucan.

Extraction of pulp

If the main product is to be pulp, the solids entering the prewash zone 32 through the filter ring 24 are immediately sprayed with a cold, acid-free liquid which is supplied from the tank 34 via line 33. This zone serves as a cooling zone in which the temperature of the pulp is reduced to a value at which any further hydrolysis comes to a standstill and a renewed precipitation of the lignin from the remaining used liquid is avoided. The consistency of the pulp desired in this section is 20%.

Liquid circulation continues through line 33 and line 35 before the pulp is introduced through the high pressure feed screw 36 and the medium pressure feed screw 37 into the high pressure device 38 where defibering is terminated before the pulp is introduced through line 39 into an open evaporation tank 40 is where it is completely cooled and from a reduced pressure of about 3.4 to 10.3 bar (about 50 to 150 psi) is freed. Relaxation and blowing off of some of the volatile components and products in the "used" liquid can take place via line 41, which is connected to the condenser line 67. The somewhat chilled, relaxed pulp is fed into a spinning dewatering device 43 by means of the screw conveyor 42, where it is continuously washed with further small amounts of cold water from line 44 in order to remove remaining water-soluble products. The drain from this dewatering device is supplied partly through line 45 to line 33 and partly through line 53 to the liquid recovery / storage system.

The dewatered pulp is fed to the screens 48 by the screw 47, while it is reslurried with water from line 49. The coarse material remaining on the screen is washed in a collector 51 and pumped back from there through line 52 to the impregnation zone 2. The ready-made fabric is washed in the first press washer 50, where it is further washed with water. The wash water, which is low in dissolved material, is returned through lines 53, 46 and 45 and partly passed over a line 53 for storing used cooking liquid in order to separate sugar therefrom. The sugar-free pulp is wiped off the wire mesh of the press washer in the device 54 and fed to the second press washer 56 via a conveying device 55, where it is washed with solvent in order to remove adsorbed or again precipitated lignin. The solvent supplied through line 57 has a high concentration of volatile organic material to compensate for the residual water coming from the previous scrubber and is preferably a good lignin solvent, such as acetone / water 80:20 or pure acetone. Since the lignin content at this stage is low - usually between 1 and 3% - this becomes liquid speed advantageously used in zone 32 as the first washing liquid and supplied to this zone through lines 58, 46 and 45. The smeared pulp wetted with solvent is passed through squeeze rollers 59 in order to further reduce the solvent content before it is fed to the packaging station 63 via a dryer 61. Collected effluent is also returned to washing zone 32 through line 60. The vapors from the dryer are fed to the condenser through line 62 to be recovered.

The dried pulp can either be packed into bales as a bulk material or formed into webs. The further processing of the pulp can be carried out in the usual way and need not be discussed here. If it is to be used as animal feed, it can be made as a pasta pulp. If it is made into a web, the drying can be stopped after the washing liquid has been driven off and the pulp can then be reslurried, after which it can be processed into sheets of customary dimensions in a machine. Alternatively, pulp to be used as feed can be dried to a moisture content of about 10%, mixed with 3% urea, 10 to 20% alfalfa flour and coloring material, such as a yellow-green dye of vegetable origin, to give the otherwise tasteless, colorless and to give odorless white pulp a better look and smell. The feed can then be pelletized and packaged with a suitable moisture content in the range of 15 to 20% as feed for ruminants.

Extraction of dissolved materials

The recovery of the organic solvent or solvents used in the solvent mixtures and ge Dissolved products from the removed cooking liquids is an essential part of the method according to the invention, since it can significantly increase the economy of the method. The used liquids collected in tanks 18 and 31 must be processed separately, since they contain dissolved solids of ultimately different uses. The deducted collected in the tank 31. Cooking liquid is supplied through line 64 to a flash evaporator 65 or a battery (not shown) of such devices where residual organic volatiles are withdrawn as steam via line 66 by controlled distillation, working to carbonize or otherwise degrade the dissolved sugars such as caramelization can be avoided. The remaining aqueous solution, which contains the dissolved sugars, a portion of the water-soluble lignin and any sugar degradation products such as humic substances, is fed through line 16 to a settling tank 77 to allow the small amount of lignin that has precipitated to be separated off.

The clear sugar solution, which contains the majority of the glucose hydrolyzed from the lignocellulose residue, is then fed to tank 79 via line 78. The sediment from tank 77 is fed via line 80 to spin drying centrifuge 85 to recover lignin at 86 while the sugar solution is returned to glucose tank 79.

The lignin thus separated, which is obtained by working up the content from the tank 18, as described below, is obtained in powder form and has an excellent solubility in the usual lignin solvents, such as ethanol, acetone, DMSO, furfural and tetrahydrofuran. The lignins can be easily purified from acetone solutions by adding them in whole or in fractions by placing them in excess water or another bad one Lignin solvent drops, it being essential that the lignin solution be prepared by ingesting powdered lignin in a minimum of acetone. Difficulties can arise in the precipitation of lignin from aqueous ethanolic solutions, since the lignin glues like rubber if the critical temperature range - 60 to 70 ° C - is not maintained. This problem can also occur in particular in the solvent separation, so that the residual solution contains large lumps of semi-melted lignin and can only be partially clarified by precipitation. The addition of acetone to such a solution in order to bring the precipitated lignin back into solution so far that a clear solution is obtained enables the lignin to be clearly precipitated by flashing off the acetone and the pulverulent lignin to be separated off. Hardwoods, such as aspenwood, usually give a finer precipitate, and the lignin precipitates are more easily separated by centrifugation than by filtration.

The prehydrolysates collected in the tank 18 contain the majority of the dissolved lignin and the valuable hemicellulose sugar and are fed via line 81 to a flash evaporator 82 or a battery (not shown) of such evaporators. The vapors released therein are passed through condenser line 83, while the aqueous solution which carries the precipitated lignin and hemicellulose sugar with it is fed through line 84 to the spin drying centrifugal washer 85 where the sugar solution from the lignin collected at 86 is passed is separated. The clear hemicellulose sugar solution from the lower part of the centrifuge is fed to tank 87. The collected condensate flows in line 67 through a preheater 68 to set the desired vapor temperature before entering the fractionation condenser 69 where the volatile components are separated according to their boiling points, which are in the range of about 50 to 250 ° C. In Such a fractionation column first contains the highest boiling fractions (furfural, levulinic acid, including acetic acid, which is formed by the conversion of acetylene), then the fractions with medium boiling points (organic liquids and volatile acids) and finally the lowest boiling organic cooking solvent (methanol, Ethanol, propanol, acetone, methyl ethyl ketone or dioxane) including the methanol formed by the decomposition of methoxylene at high temperature.

The distillates from this column are one through lines 92

Number of tanks, such as 93, 94, 95 fed. Methanol is recovered from the top of the column along with most of the acetone and its azeotrope with water containing 18% water. Methanol does not appreciably affect the dissolving power of other organic solvents used in the solvent mixture, but its amount should be kept below 5 to 10% of the mixture.

The acetone is separated from the azeotrope acetone / water by passing the azeotrope through a rectification column 71, after which the anhydrous solvent is returned via line 74 to tank 75, or the aqueous solvent can be fed to tank 73. The compositions of the various cooking liquids are adjusted by drawing off solvent from tanks 75 and 73, from water line 89 and from acid tank 88, the mixing being regulated at 90, from where the mixture is passed through line 91 to tanks 8 (first solvent mixture) , 23 (second solvent mixture) and 34 (washing liquid) is supplied.

An analysis of the products obtained at the end of cooking in the second stage is compiled for aspen and Douglas fir in Table XIII. T from XIII

Wood Temp. Time AusRest - solved. Eq. M F

° C min booty lignin or on HMF

Pulp

%%%%%%%%

200 7 50.6 1.4 85 6.8 51 61 93 65 1.0

Aspen 200 8 43.5 0.2 91 17.0 76 86 40 70 5.8

200 7 47.5 3.5 86 20 95 34 57 20 1.0

D-T

200 8 41.8 2.7 95 40 18 5 1 1 6.2

D-T = Douglas fir Eq. = Glucose M = mannose G = galactose X = xylose A = arabinose F = furfural

HMF = hydroxymethylfurfural

All of the sugars listed in Table XIII were separated and recovered as reducible monosaccharides and did not require secondary hydrolysis to convert them to this state, as was required with most known saccharification products. The lignin in the solution was obtained as "precipitated" lignin and is given as a percentage of the potentially recoverable lignin. No derivative of the lignin with components of the cooking liquid or with materials formed during the hydrolysis was isolated. The lignin retained its good solubility in most "good" lignin solvents, even after several acetone precipitations.

After 8 minutes of cooking time, the pulps contained 95% glucan and had the following degree of whiteness, measured on the GE scale, the first number being 7 minutes of cooking time and the second number being 8 Minutes of cooking time:

Aspen 70%, 78%; Douglas fir 57%, 62%. The relative crystallinity of the pulps was 0.6. and was thus higher than that of the starting material, namely 0.4 to 0.45.

The low yield of furfural measured at a cooking time of 7 minutes can be attributed to the fact that hemicellulose and glucose were separated from the first cooking liquid drawn off before further hydration could take place.

It is interesting that about 2% organic acids and 3% methanol were also obtained at the end of the second stage boiling.

The properties of a number of high quality pulps, as can be obtained at the end of dryer 61, were determined by testing soft woods and hard woods, namely spruce, southern pine and Douglas fir, as well as aspen and birch, in a further series of tests Agricultural residues, namely sugar cane bark and wheat straw in the pulp cooker. Each test consisted of 2 cooking stages, the temperature of the first solvent mixture being below 185 ° C and the time 5 to 6 minutes and the final cooking at 200 ° C for a sufficient time that the fiber was only exposed to the residue by the action of liquid in the liquid could be separated, were carried out. The acid catalyst was either 0.02ra HCl or 0.025m or 0.05m oxalic acid or 0.025m HCl / KCl, which adjusted the pH to 2.2.

The pulps were analyzed according to standard TAPPI methods. The kappa number of the lignin according to T-236; the viscosity according to T-230; the whiteness according to T-217; the Canadian standard freeness according to T-227; the standard strength determinations after evaluation of the grinding speed in a PFI mill according to BCIT B-6-1; and the her Standard hand sheets according to T-205. The strength tests were TAPPI. Standard T-220, T-231, T-403, T-404 and T-414. The hand sheet weights ranged from 59 to 61 g / m ² . Some of the pulps of Table XIV underwent a modified three-step treatment, namely chlorination, alkali extraction, hypochlorite bleaching according to BCIT T-4. 5. 6-1, which was developed for bleaching small amounts of pulp. The table shows some values for pulps obtained by the Kraft process, to which it should be noted that, although the chemical concentrations and consistencies proposed for the standard bleaching processes were adhered to, the bleaching according to the process according to Pulp modifications obtained according to the invention were carried out by changing the tents from 60 to 30 minutes for chlorination at 20 ° C, from 90 to 10 minutes for alkali extraction at 75 ° C and from 90 to 10 minutes for the hypochlorite stage as used for the production of Kraft pulps with much lower kappa numbers have been reduced. The fibers were washed on a Büchner funnel and turned into even cakes over filter paper and dried between blotting paper until they were air dry. The whiteness of the bleached pulp was measured according to TAPPI standard T-218. Table XV shows the sometimes very slight changes in the properties of the pulp due to the mild bleaching that is required to achieve a very high degree of whiteness.

T a b e l l e XIV-B

Lignocellu pulp loose firmness shadow, 500 CFS acid, 300 CFS

Cooking time min. REVS. Break. TEAR Burst O-Span. REVS. Break. Tear burst O-Span.

Ling. Ling. m m

ASP FORCE - 6500 56 114 - 9800 89 110

ASP-OXA-10 550 5370 53 20 16622 1400 6970 49 32 17665

ASP-OXA-15 1500 6570 49 27 16200 3920 7800 65 40 16500

ASP-HCl-8 - 4330 23 14 13591 - - - - -

ASP-B-10 100 4800 45 27 14000 1230 6700 39 24 16750

SPR-KRAFT - - 11-200 108 117

SPR-OXΛ-20 3000 7500 89 83 13600 4300 7700 82 47 17600

SPR-HCl-10 - 5460 19 18 11579 - - - -

SPR-HB-10 200 5600 72 29 17450 1750 7200 47 39 17500

BAG-E-KRΛFT - - 96OO 74 55

SCAN-OXA-9 - 7200 46 34 15560 1000 8200 46 39 14970

BAG-HCl-6 - 4900 21 13 11768 - - - - -

WHE-KRAFT - - - - - 6700 50 40

WHE-OXA-10 8000 70 34 22000 850 9800 63 50 20260

WHE-HCl-8 - 5200 25 15 12000 - - - - -

SOP-OXA-10 670 4500 64 16 14850 1170 4900 59 19 14870

SOP-HB-10 600 3200 85 13 15760 2900 4300 73 18 15600

BIR POWER - 7000 88 60 - 8600 73 73

BIR-OXA-15 700 10230 71 57 17100 1600 10560 68 65 18700

DF-OXΛ-15 2000 6150 88 38 17300 2950 6900 71 35 17850

T a b e l l e XV

Wood type Yield Rest White CFS 300 and% ignin degree Breaking TEAR BURST

Bleach%% Length, m state

Spruce: not bleached 57.3 10.3 45 7700 82.0 47.0

Bleach 49.6 - - 84 6960 67.7 38.4

Birch: not bleached 60.88 3.25 43 10560 68.0 65

Bleach 57.2 - - 86 9 460 57.6 64.8

The above description describes the method by which the new solvolysis methods for separating the fiber from the cellulose component of lignocellulose can be carried out. It has been shown that certain volatile water-soluble organic liquids which are mixed with water lignin solvents can be mixed with an acidic catalytic compound, preferably a mild acid such as an organic acid or a buffered strong acid, to form hemicellulose and hydrolysis Dissolve lignin within minutes of impregnating the lignocellulose with the hot solvent mixture containing such a catalyst. If a solvent mixture containing a mild catalyst is used at the beginning, a fiber strength of the released cellulose of almost the natural DP value can be achieved. By removing the solvent mixture and cooling and separating the volatile materials, the dissolved hemicellulose sugar can be obtained in high yield and high purity and pure lignin as a pale powder. From hard A fiber with DP values of over 1000 can be obtained from wood and a fiber with DP values of over 800 from soft woods. If the lignocellulose residue is further treated with hot solvent mixture using a strong acid catalyst, the saccharification can be carried out to any stage of solids and sugar dissolution and sugar dehydration products, organic acids, furfural and methanol can be obtained.

With the method according to the invention, a substantial cost saving is possible compared to Kraft methods, in which 30 to 40% chemicals per ton of wood are used, since in the method according to the invention only 3 to 6% of acid catalyst, based on the weight of the wood , be used. The continuous recovery of organic solvent and the extraction of high quality lignin and sugars more than eliminates the cost of non-recoverable chemicals. In addition, organic acids are formed from the lignocellulose.

Claims

Patent claims 1. A process for separating the fibers from the cellulose component of lignocellulose, characterized in that comminuted lignocellulose with a predominant volume of a hot aqueous acidified organic solvent mixture of 70 to 30 parts of water, 30 to 70 parts of a volatile organic liquid solvent of the groups water-soluble low molecular weight aliphatic alcohols and water soluble low molecular weight aliphatic ketones and mixtures thereof, the solubility parameter of the liquid organic solvent chosen being in the range from 10 to 13 and an acidic hydrolysis catalyst in such an amount that the pH of the solvent mixture is in the range of 1 , 7 to 3.5, the acid catalyst from the group of organic acids oxalic, maleic, o-phthalic, L-apple, amber, nicotinic, salicylic and trifluoroacetic acid, from the group of strong acids hydrochloric acid Sulfuric acid Phosphoric acid and nitric acid and selected from the group with their neutral buffering salts, impregnated, the impregnated lignocellulose of the de-lignifying and saccharifying effect of the solvent mixture at a temperature in the range from 160 to 210 ° C. for a time of at least 3 minutes and sufficiently long, to make the fibers separable from the suspended cellulose residue by fluid movement, then suspends, then removes the cooking liquid, washes the cellulose residue with a solvent from the above-mentioned groups of organic liquid solvents and then washed the residue with water. 2. The method according to claim 1, characterized in that the liquid organic solvent selected for the solvent mixture is ethanol or acetone and the liquid washing solvent is acetone or ethanol. 3. decay according to claim 2, characterized in that the liquid organic solvent is ethanol and the hydrolyzing acid catalyst is oxalic acid. 4. The method according to claim 2, characterized in that the liquid organic solvent is ethanol and the hydrolyzing acid catalyst is maleic acid. 5. The method according to claim 2, characterized in that the liquid organic solvent is ethanol and the hydrolyzing acid catalyst is o-phthalic acid. 6. The method according to claim 2, characterized in that the liquid organic solvent is ethanol and the hydrolyzing acid catalyst is L-malic acid. 7- The method according to claim 2, characterized in that the liquid organic solvent is ethanol and the hydrolyzing acid catalyst is succinic acid. 8. The method according to claim 2, characterized in that the liquid organic solvent is ethanol and the hydrolyzing acid catalyst is nicotinic acid. 9. The method according to claim 2, characterized in that the liquid organic solvent is ethanol and the hydrolyzing acid catalyst is salicylic acid. 10. The method according to claim 2, characterized in that the liquid organic solvent is ethanol and the hydrolyzing acid catalyst is trifluoroacetic acid. 11. The method according to claim 2, characterized in that the liquid organic solvent acetone and the hydrolyzing acid Catalyst is hydrochloric acid. 12. The method according to claim 2, characterized in that the liquid organic solvent ethanol and the hydrolyzing acid catalyst is a mixture of potassium chloride and hydrochloric acid. 13. The method according to claim 2, characterized in that the low-boiling volatile materials in the stripped cooking liquid and the washing solvent are evaporated to precipitate lignin, the lignin is separated from aqueous sugar solution, the separated lignin is dissolved again in a lignin solvent to saturation and the lignin solution is spray dried or mixed with a predominant volume of water to disperse a precipitate of finely divided lignin. 14. The method according to claim 13, characterized in that the lignin solvent is selected from the group of liquid organic solvents from acetone, furfural, wench methyl sulfoxide or tetrahydrofuran. 15. The method according to claim 14, characterized in that the aqueous sugar solution is concentrated by stripping steam to a content of dissolved solids of 20 to 50%. 16. The method according to claim 13, characterized in that the volatile materials are separated by fractional distillation in order to recover the liquid organic solvent and the liquid washing solution agent and to recover volatile thermal conversion products and volatile hydrolysis products, namely methanol, formic acid and acetic acid. 17. The method according to claim 15, characterized in that the volatile materials by. Steam streaks are removed, fractionated-condensed according to their boiling points to obtain the liquid organic solvents, the liquid washing solvent and the volatile thermal conversion products as well as the volatile hydrolysis products, namely methanol, furfural, 5-hydroxymethylfurfural, levulinic acid, formic acid and acetic acid. 18. The method according to claim 1, characterized in that the acidified solvent mixture is mixed with the lignocellulose in a weight ratio between 1: 4 and 1:12. 19. The method according to claim 2, characterized in that the acidified aqueous organic solvent mixture with comminuted lignocellulose is mixed in a pressure vessel with inlet and outlet and the solvent mixture is continuously circulated through the lignocellulose, so that the residence time of the cooking liquid is not longer than 5 minutes , after which the liquid is withdrawn while fresh solvent mixture is introduced to replace the withdrawn mixture. 20. The method according to claim 19, characterized in that the lignocellulose and the solvent mixture are moved towards the outlet, the solvent mixture being moved at a higher speed than the lignocellulose. 21. A method for separating the fibers from the cellulose component of lignocellulose, characterized in that particles of the whole lignocellulose with a predominant volume of a first hot aqueous acidified organic solvent mixture of 40 to 60 parts of water, 60 to 40 parts in a river organic solvents from the group of ethanol and acetone and a first hydrolyzing acid catalyst in such an amount that the pH of the solvent mixture is in the range from 3.5 to 1.7, from the group of the organic acids maleic, oxalic, o- Impregnated phthalic, L-apple, succinic, nicotinic, salicylic and trifluoroacetic acid, which then exposes the impregnated lignocellulose to the delignifying and saccharifying solution of this first solvent mixture at a temperature of approximately 10 ° C. and for a period of approximately 5 minutes subtracts the cooking liquid from the partially delignified lignocellulose, then the partially delignified residue - with a second aqueous acidified organic solvent mixture, which does not have a second acidic hydrolyzing catalyst from the group of inorganic acids from which the first acidic hydrolysis catalyst was chosen, at a second digestion temperature of over 210 ° C and sufficiently long to make the fibers separable by liquid movement, boils, then removes the second cooking liquid, washes the cellulose residue with acetone and then the. Wash residue with water to obtain a pulp of cellulose fibers of high degree of polymerization. 22. The method according to claim 21, characterized in that the first and the second acid hydrolyzing catalyst oxalic acid and the organic solvent selected for the cooking mixtures is ethanol. 23. The method according to claim 22, characterized in that the first and second aqueous organic solvent mixture are mixed with the lignocellulose particles in a pressure vessel with inlet and outlet and the solvent mixture is continuously circulated through the lignocellulose, the first and second solvent mixture together with the lignocellulose in Direction to Outlet is moved through the container and the speed of movement of each mixture is greater than the speed of movement of the lignocellulose. 24. The method according to claim 21, characterized in that each of the volatile materials present in the stripped cooking liquid and the washing solvent is evaporated in order to precipitate the lignin dissolved therein, the lignin is separated from aqueous sugar solution, the separated lignin until saturated in one Lignin solvent is redissolved and the lignin solution is spray dried or mixed with a predominant volume of water to disperse precipitated fine lignin. 25. The method according to claim 24, characterized in that the aqueous sugar solution obtained from the withdrawn first solvent mixture is concentrated to a solids content of 20 to 50%. 26. The method according to claim 24, characterized in that the aqueous sugar solution obtained from the second solvent mixture is concentrated to a solids content of 20 to 50%. 27. The method according to claim 24, characterized in that the solvent for the lignin obtained from the first solvent mixture is acetone and the solvent for the lignin obtained from the second solvent mixture is selected from the group consisting of acetone, furfurai, Dirnethylsulfoxid and tetrahydrofuran. 28. A method for separating the fibers from the cellulose component of lignocellulose and recovering the fibers in a state of reduced degree of polymerization, characterized in that particles of the whole lignocellulose with a main volume fraction a first hot aqueous acidified organic solvent mixture of 40 to 60 parts of water and 60 to 40 parts of a first organic liquid solvent from the group of volatile water-soluble organic solvents from ethanol and acetone and a first acidic hydrolysis catalyst in such an amount that the pH of the solvent mixture in the Range from 3.5 to 1.7, impregnated from the group of the organic acids maleic, oxalic, o-phthalic, L-apple, succinic, nicotinic, salicylic and trifluoroacetic acid, the impregnated lignocellulose of the delignifying and saccharifying effect of the first solvent mixture at a temperature of about 100 ° C for a time of about 5 minutes, then withdrawing the first cooking liquid from the partially delignified lignocellulose, then the partially delignified lignocellulose residue with a main volume based on this residue in a second aqueous ans The organic solvent mixture, which contains a second acidic hydrolysis catalyst from the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, at a digestion temperature in the range from 180 to 200 ° C. for a time sufficient to cause partial saccharification of glucan and cellulose fiber of low degree of polymerization, boils, then draws off the second cooking liquid and washes the residue with water. 29. The method according to claim 25, characterized in that the first organic solvent is ethanol and the second solvent mixture contains either ethanol or acetone, the acidified aqueous organic solvent mixture in a pressure vessel with inlet and outlet mixed with the lignocellulose and each of the solvent mixture during the cooking times are continuously circulated through the lignocellulose, the first solvent mixture parallel to the lignocellulose towards The outlet is rotated at a rate greater than that of the movement of the lignocellulose and the second solvent mixture is moved in countercurrent to the movement of the lignocellulose residue. 30. The method according to claim 28, characterized in that the low-boiling volatile materials in each of the withdrawn cooking liquids and the washing solvent are evaporated to precipitate lignin, the lignin is separated from the aqueous sugar solution, the separated lignin is dissolved again in a lignin solvent until saturation and the lignin solution is spray dried or mixed with a predominant volume of water to disperse a precipitate of finely divided lignin. 31. The method according to claim 30, characterized in that the aqueous sugar solution obtained from the first solvent mixture is concentrated to a solids content of hemicellulose conversion sugars of 20 to 50%. 32. The method according to claim 30, characterized in that the aqueous sugar solution obtained from the withdrawn second solvent mixture is concentrated to a solids content of 20 to 50%. 33. The method according to claim 30 *, characterized in that the solvent for the lignin acetone obtained from the first solvent mixture and the solvent for the lignin obtained from the second solvent mixture is selected from the group consisting of acetone, furfural, dirnethyl sulfoxide and tetrahydrofuran. 34. Process for separating the fibers from the cellulose component of lignocellulose and obtaining a microcrystalline residue from these fibers, characterized in that the whole comminuted lignocellulose with a main volume of a first hot aqueous acidified organic solvent mixture of 40 to 60 parts of water, 60 to 40 parts of a first organic solvent from the group of volatile water-soluble organic solvents ethanol and acetone and a first acidic hydrolysis catalyst in such an amount that the solvent mixture has a pH in the range from 3.5 to 1.7, from the group of the organic acids maleic, o-phthalic, oxalic, L-apple, amber -, nicotinic, salicylic and trifluoroacetic acid, which exposes the impregnated lignocellulose to the de-lignifying and saccharifying effect of the first solvent mixture at a temperature of approximately 180 ° C. for a time of approximately 5 minutes, then removes the first cooking fluid from the partially delignified lignocellulose, afterwards this partially delignified residue with a main part by volume, based on the residue, of a second aqueous acidified organic solvent mixture which contains a second acidic hydrolysis catalyst from the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid at a digestion temperature of 200 to 210 ° C for a sufficient time to remove the cellulose to hydrolyze, boils so that the fiber structure is broken down into the crystalline region of non-fiber form and the absence of amorphous polyglucose, then the second cooking liquid is removed and the microcrystalline residue is washed with water. 35. The method according to claim 34, characterized in that the first organic solvent is ethanol and the second solvent mixture contains either ethanol or acetone, the acidified aqueous organic solvent mixtures are mixed in a pressure vessel with inlet and outlet with the lignocellulose and the first solvent mixture continuously in Direction parallel with the lignocellulose and at a rate that is greater is that of lignocellulose through which lignocellulose is circulated and the second solvent mixture is continuously circulated in countercurrent through the partially delignified lignocellulose. 36. The method according to claim 34, characterized in that the low-boiling volatile constituents present in each withdrawn cooking liquid and in the washing solvent are evaporated to precipitate the lignin, the lignin is separated from the aqueous sugar solution, the separated lignin until saturated in one Lignin solvent is redissolved and the lignin solution is spray dried or mixed with a predominant volura portion of water to disperse a precipitate of fine lignin. 37. The method according to claim 36, characterized in that the solvent for lignin by the first. Solvent mixture is separated, is acetone and the lignin solvent, which is separated from the second solvent mixture, is acetone, furfural, methyl sulfoxide or tetrahydrofuran. 38. The method according to claim 36, characterized in that said volatile materials are separated by fractional distillation so that the organic liquid solvents and volatile thermal conversion products and volatile hydrolysis products including methanol, formic acid and acetic acid are obtained. 39. The method according to claim 36, characterized in that the aqueous sugar solution obtained from the withdrawn first solvent mixture is concentrated to a solids content of hemicellulose conversion sugars of 20 to 50%. 40. The method according to claim 36, characterized in that the aqueous sugar solution is concentrated by steam stripping to a solids content of 20 to 50% and the volatile constituents are fractionally condensed in the vapor phase to the organic liquid solvent and the volatile thermal To win conversion products of hydrolysis. 41. Process for separating the fibers from the cellulose constituent of lignocellulose and obtaining lignin and hydrolysis products from hemicellulose and cellulose, characterized in that the whole of the comminuted lignocellulose with a main part by volume of a first hot, aqueous acidified organic solvent mixture composed of 70 to 30 parts of water , 30 to 70 parts of an organic solvent from the group of ethanol and acetone and a hydrolyzing acid catalyst in an amount sufficient to give the solvent mixture a pH in the range from 3.5 to 2.2, from the group of the strong acids hydrochloric acid, Impregnated sulfuric acid, phosphoric acid and nitric acid, the impregnated lignocellulose at a temperature of about 180 ° C and for a time of about 5 minutes, which is sufficient to release the cellulose fibers, exposed to the de-lignifying and saccharifying effect of the solvent mixture, then the first cooking liquid eit deducts and the lignocellulose residue with fresh aqueous acidified organic solvent mixture, which is the same as the first solvent mixture with the difference that the second solvent mixture has a higher acid concentration, namely a pH range of 2.2 to 1.7, and the mixture at a temperature of about 210 ° C and boils for a sufficient time to practically completely dissolve the cellulose, then draws off the second cooking liquid, which evaporates the low-boiling volatile materials present in each cooking liquid to precipitate lignin, which separates lignin from the liquids so that a residual liquid who have dissolved sugar and other conversion products contains, is obtained, the condensed volatile materials are recovered and the dissolved sugars and other conversion products are separated from each of the residual liquids. 42. The method according to claim 41, characterized in that lignocellulose and cooking liquid are used in a ratio of about 1:12. 43. A process for converting lignocellulose to hydrolysis and dehydration products of lignin, hemicellulose and cellulose, including furfurals, organic acids, methanol and residual sugars, characterized in that crushed structured plant material with a main volume of a hot aqueous acidified organic solvent mixture of 70 to 30 parts H ₂ O, 30 to 70 parts of a liquid volatile organic solvent with a solubility parameter in the range of 10 to 13 of the group of water-soluble low molecular weight aliphatic alcohols and low molecular weight aliphatic ketones and mixtures thereof and an acid hydrolyzing catalyst from the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid in such an amount that the solvent mixture has a pH in the range from 3.5 up to 1.7, impregnated at a temperature of about 210 ° C and for a sufficient time to saccharify practically all glucan and convert practically all sugars formed by the hydrolysis to their dehydration and degradation products, then volatile components from the cooking liquid evaporates with a vapor phase in the temperature range of 50 to 250 ° C and separates the volatile materials by fractional distillation, and sugar and lignin are recovered from the residue. 44. The method according to claim 43, characterized in that the liquid organic solvent is acetone and the weight ratio ratio of lignocellulose to cooking liquid is initially around 1:12. 45. Process for separating the fibers of the cellulose constituent from lignocellulose, characterized in that the whole of the comminuted lignocellulose with a major part by volume of a hot aqueous acidified organic solvent mixture composed of 70 to 30 parts of water and 30 to 70 parts of a volatile liquid organic solvent a solubility parameter in the range from 10 to 13 from the groups of the water-soluble low-molecular aliphatic alcohols and the water-soluble low-molecular aliphatic ketones and mixtures thereof and. a hydrolysis catalyst from the group of organic acids maleic, oxai, o-phthalic, L-apple, succinic, nicotinic, salicylic and trifluoroacetic acid in such an amount that the pH of the solvent mixture in the range of 3.5 to 1.7, when impregnated, the impregnated lignocellulose is at a temperature in the range of 160 to about 180 ° C for a sufficient time to dissolve the greater part of the hemicellulose and the greater part of the lignin so that the fibers after Boiling are not yet released, but can be released by vigorous mechanical agitation of an aqueous suspension of the lignocellulose residue, subjected, then the cooking liquid is removed from the residue, the residue is boiled with acetone and then washed with water, the residue is dispersed in water and the dispersed residue refined under high pressure to obtain a mechanical pulp of high strength. 46. The method according to claim 45, characterized in that the lignocellulose and the aqueous organic acidified solvent mixture are introduced with mixing into a pressure vessel with inlet and outlet in a weight ratio between 1: 4 and 1:12 and are led together towards the outlet through the container, the speed of movement of the solvent mixture being greater than that of the lignocellulose. 47. The method according to claim 45, characterized in that the liquid organic solvent is ethanol or acetone and the liquid washing solvent is acetone and that the lignocellulose is exposed to the de-lignifying and saccharifying effect of the solvent mixture for a period of not more than 5 minutes. 48. Process for separating the fibers from the cellulose portion of lignocellulose, characterized in that the whole comminuted lignocellulose with a main volume portion of a hot aqueous organic acidified solvent mixture of 70 to 30 parts of water, 30 to 70 parts of a liquid volatile organic solvent the groups of the water-soluble low-molecular aliphatic alcohols and the water-soluble low-molecular aliphatic ketones and mixtures thereof, whose solubility parameter is in the range from 10 to 13, and an acidic hydrolysis catalyst from the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid and the group with their neutral salts buffered strong acids in such an amount that the pH of the solvent mixture is adjusted in the range from 3.5 to 1.7, impregnated the impregnated lignocellulose of the de-lignifying and saccharifying effect ng of the solvent mixture at a temperature in the range of about 1β0 to about 180 ° C for a time sufficient to cause the dissolution of the greater part of the hemicellulose and the greater part of the lignin so that the fibers do not yet boil are released, but can be released by vigorous mechanical movement of an aqueous suspension of the lignocellulose residue, then the cooking liquid from the cellulose residue pulls, the residue washed with acetone and then with water, the residue dispersed in water, and the dispersed residue refined under high pressure to form a mechanical pulp of high strength. 49. The method according to claim 48, characterized in that the lignocellulose and the acidified aqueous-organic solvent mixture are introduced with mixing into a pressure vessel with inlet and outlet in a weight ratio between 1: 4 and 1:12 and together in the direction of the outlet through the Containers are guided, the speed of movement of the solvent mixture is greater than that of the movement of the lignocellulose. 50. The method according to claim 48, characterized in that the lignocellulose is exposed to the de-lignifying and saccharifying effect of the solvent mixture for a period of not more than 5 minutes. 51. A continuous process for releasing the fibers from the cellulose constituent of lignocellulose, characterized in that - particles of lignocellulose are introduced through an inlet into a first pressure vessel, said first vessel at least one inlet and at least one, at a distance along the length of the vessel from has arranged outlet and can hold its contents under increased pressure, introduces through the inlet a first aqueous acidified solvent mixture of 30 to 70 parts of water, 70 to 30 parts of a liquid volatile water-soluble organic solvent and an acidic hydrolyzation catalyst in such an amount that the pH of the mixture is in the range of 1.7 to 3.5 the liquid organic solvent is selected from the group of water-soluble low-molecular aliphatic alcohols and the group of water-soluble low-molecular aliphatic ketones and mixtures thereof, whose solubility parameter is in the range from 10 to 13, introduces a weight ratio of introduced solvent and feed of at least 4: 1 and heat the container to maintain its contents at a temperature of at least 160 ° C, but not above 210 ° C, while lignocellulose and solvent mixture toward the outlet through the container agitated, - circulates the solvent mixture such that its speed is considerably greater than the speed of the comminuted lignocellulose, and solvent mixture containing lignin and sugar dissolved by pulling out an outlet to limit the residence time to a certain value, - from a mouse let this first container draw off lignocellulose residue and impregnation solvent without pressure solution, - separate solvent mixture from the withdrawn lignocellulose residue until only a small volume of liquid remains in the lignocellulose fraction, - transfer the lignocellulose residue through an inlet into at least one second pressure container, one of which transfers one Inlet and outlet, spaced apart along the length of the container and capable of holding its contents under pressure, introduces a second aqueous acidified solvent mixture of 70 to 30 to 70 parts of a liquid volatile water-soluble organic solvent and an acidic hydrolysis catalyst in sufficient amount to adjust the pH of the mixture adjust the range from 1.7 to 3.5, the liquid organic solvent being selected from the group of the water-soluble low-molecular aliphatic alcohols and the water-soluble low-molecular aliphatic ketones and mixtures thereof, whose solubility parameter is in the range from 10 to 13 , - maintains a weight ratio of solvent mixture to lignocellulose residue when entering the second pressure vessel in the range from 10: 1 to 4: 1 and adds heat to the content so that a temperature close to, but not above, 210 ° C. is maintained while one leads the lignocellulose residue and the solvent mixture in the direction of the outlet, - the second solvent mixture flows through the second container and solvent mixture is withdrawn from an outlet while observing a certain dwell time, - leads the lignocellulose residue through the second container at such a speed that the koo Particles are discharged from an outlet in such a way that the cellulose lozenges are freely separable, - the bridging agent mixture and dissolved lignin and sugar-containing particles are withdrawn from the second container without bridging, - the solvent mixture is withdrawn from the cooked residue, - the cellulose residue is removed in succession Washing liquids from pure organic solvent and then liquid aqueous organic solvent and then extracted with water and washed, and - the washed cellulose fiber mass extracted with solvent brings out. 52. Continuous process according to claim 51, characterized in that the first solvent mixture withdrawn at a Non-coking temperature is distilled to separate volatile materials and. Precipitate lignin in a syrupy residue, condense the volatile materials to recover the liquid organic solvent, and reuse the recovered liquid organic solvent in the process. 53. Continuous process according to claim 51, characterized in that the withdrawn second solvent mixture is subjected to a distillation at non-coking temperature in order to separate volatile materials and to precipitate dissolved residual lignin, the volatile materials being condensed to recover the liquid organic solvent and the sugar and liquid residue containing dehydration products is recovered. 54. Continuous process according to claim 51, characterized in that the acidic hydrolysis catalyst contained in the first or the second solvent mixture from the group of acids hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, maleic acid, o-phthalic acid, L-malic acid, succinic acid, Nicotinic acid, salicylic acid and trifluoroacetic acid and mixtures of a neutral buffer salt of a selected strong acid with this strong acid is selected. 55. Continuous process according to claim 54, characterized in that the cooking temperature in d in the first container is approximately 180 ° C and the cooking temperature in the second container is approximately 210 ° C and the pH of the first solvent mixture in the range of 1.7 to 2 , 2 lies. 56. Continuous process according to claim 51, characterized in that the liquid organic solvent in the first Solvent mixture is ethanol or acetone and is mixed with an equal weight proportion of water, the acidic hydrolysis catalyst for the first solvent mixture from the groups of acids oxalic, maleic, o-phthalic, L-apple, amber, nicotine, salicyl and trifluoroacetic acid and mixtures of a neutral buffer salt of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid in a mixture with the corresponding strong acid is selected so that the pH of the solvent mixture is adjusted in the range from 1.7 to 2.2, the liquid organic solvent for the second solvent mixture is acetone, which is mixed with water in a ratio of 40 to 60 volumes of acetone to 60 to 40 volumes of water, and the weight ratio of lignocellulose to solvent mixture is set between 1: 4 and 1:10, and that for the second Solvent mixture used acidic hydrolysis catalyst from the group of the strong n acids hydrochloric acid sulfuric acid, phosphoric acid and nitric acid is chosen. 57. The continuous process according to claim 56, wherein the boiling of the lignocellulose residue in the second pressure vessel is continued until a partial saccharification of glucan and a practically complete fiber release have occurred, characterized by breaking the microfibrils into crystalline particles without fiber structure and by the absence of amorphous polyglucose and by dehydrating the cellulose residue extracted and washed with solvent to a practically anhydrous cellulose powder. 58. Continuous process for de-lignifying lignocellulose and practically completely converting the glucan into sugar dehydration and degradation products, characterized in that - introduces shredded lignocellulose through an inlet into a pressure vessel, this vessel having at least a pair of inlets or outlets at each end for the introduction and discharge of materials and capable of holding its contents under increased pressure, - an acidified aqueous organic solvent mixture of 30 to 70 parts of water, 70 to 30 parts of a water-soluble organic solvent from the group acetone and ethanol and an acid from the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid in such an amount that the pH of the solvent mixture in the range of 1 , 7 to 3.5 is set, selects, introduces, - maintains a feed to solvent mixture ratio of 1 part lignocellulose to 10 to 15 parts solvent mixture, - adds heat to the contents of the container so that its temperature is about 210 ° C while crushing the lignocellulose towards de m moved at a distance from the inlet while circulating solvents in countercurrent to the direction of advancement of the lignocellulose, solvent mixture containing lignin and sugar dissolved, withdrawing from an outlet near the inlet and freshly heated solvent mixture through one of feeds this inlet distant inlet, distilled stripped solvent mixture at non-coking temperature to recover the ethanol or acetone as condensate and precipitate the lignin from a syrupy residue and introduces the syrupy residue with the condensate through the second inlet removed from the first, which Exposes lignocellulose to the saccharification effect of the solvent mixture for so long that practically no solid organic residue reaches the outlet removed from the inlet and so long that the dissolved products formed from cellulose are dehydrated to furfurals of pentoses and hexoses, and - withdraws a liquid containing the sugar dehydration products. 59. Continuous process according to claim 58, characterized in that the distillation is carried out at such a temperature that the autolytically produced volatile organic compounds methanol, 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde and the organic acids present in lignocellulose and the autolytic generated acids acetic acid, formic acid, lactic acid, levulinic acid, plicatinic acid, tannic acid, tartaric acid and oxalic acid remain in the syrupy residue. 60. lignin in low molecular weight in powder form prepared according to the claimed process.