DD142562A5 - PROCESS FOR REMOVING LIGNOCELLULOSE MATERIALS - Google Patents

Description

Process for separating fibers from the cellulose component of lignocellulose

Field of application of the invention

The invention relates to a process for the delignification and saccharification of vegetable lignocellulosic materials with concomitant use of organic solvents.

More particularly, the invention relates to a novel process for the rapid dissolution of lignin and hemicellulose from forest and agricultural materials such as wood, straw, bamboo, and recovery of cellulosic fiber material or its conversion products, lignin and sugars, or their conversion products.

The cellulosic pulp produced according to the invention can be advantageously used for papermaking or as a filler for ruminants.

The recovered lignin and sugar are valuable raw materials in the phenol, sugar and sugar fermentation industries.

Characteristic of the known technical solution

Wood consists of about 4-0 to 50% by weight of cellulose polymer in fiber form, namely a polymer of β-anhydroglucoside

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units, such as .15 to 20% by weight of hemicellulose, which consists of mannose, xylose and other hexose and pentagonal sugars and uronic acids, and about 20 to about 30% by weight of lignin, which is selected from a number of lignin. zen consists of phenolic structural units in polymeric form. As further components, waxes, gums and masked mineral compounds may be present in varying amounts.

The aim of the wood recycling processes is to separate their constituents as cleanly as possible and with the least possible degradation of the constituents or the subcomponent of a constituent, ie to recover each constituent in its natural form. The "cellulose fiber separation processes require the removal of as much of the lignin as possible in order to disperse the fibers into a pulp, to obtain a fiber of high bonding capacity, and to minimize the need for bleaching." The usefulness of cellulose as a fodder becomes strong improved Vienne the Eestligningehalt to below 5% is decreased. Since the lignins and hemicellulose surround the crystalline cellulose fibers as the cell walls forming layers, the removal of these amorphous, relatively porous substances by chemical attack has been the basis of most known separation method.

The question of how lignin, hemicellulose and cellulose polymer are linked together is still largely unresolved. There is some evidence that there is some binding between a small proportion of lignin and a proportion of hemicellulose.

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With great effort, chemical separation techniques have been developed, but all involve modification or degradation of lignin and hemicellulose, which are rapidly attacked at high temperature and high acidity or alkalinity. The crystalline cellulose is also degraded considerably, in particular by breaking the polymer chains at the disordered crystal sites. The fibers separated by the known acid-catalyzed processes still contain undissolved lignin and hemicellulose, so that further treatments with alkaline solutions and / or bleaching agents are required, through which further degradation of the cellulose takes place.

For a historical overview of a large number of known processes for producing chemical pulps using organic solvents and various catalysts, see the article "A Review of Lesser-Known Pulping Methods" by CJ. Brounstein, Pulp and Paper Magazine of Canada, January 1952. Further publications on the use of mixtures of organic solvents to make pulps are U.S. Patent 3,585 (1971), 2,959,900 (196) and 4,003,702 (1977).

Object of the invention

The aim of the invention is to provide a simple and wirtschaftlieheη process can be separated with a short T im _e cellulose fiber, lignocellulose and hemicellulose from Porst- and Agrikulturmaterialien. In particular, the components should neither be modified nor degraded, so that cellulose fiber ^ with

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high degree of polymerization can be isolated. Explanation of the essence of the invention

The invention has for its object to provide a novel acid-catalyzed hydrolysis process for the rapid solution of lignin and hemicellulose from Porst- and agricultural materials and recovery of cellulose fiber material or its conversion products, lignin and sugars or their conversion products, in particular to find a new solvent.

According to the invention a new solvent mixture consisting of water and a liquid organic solvent, catalyzed by an acidic additive is to reduce the "Z _e it necessary to separate the cellulose fibers of lignocellulose and allows the recovery of fiber in a high degree of polymerization, the the solvent mixture is adjusted to a pH in the range of 3 to 5 to 1.7 is used.

For carrying out the process according to the invention, a boiling liquid of water and an organic solvent containing an acidic catalyst is used, with which, at elevated temperatures in the range of 160 to 210 ° C, the lignocellulose contained in the lignocellulose rapidly and is dissolved out without derivatization and hemicellulose is hydrolyzed so that the lignocellulose is transferred within a few minutes of cooking time to a pulp of a dispersion of cellulosic fibers in a solution of lignin and sugars. Such pulps have one

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Alternatively, the lignocellulose-depleted lignocellulose residue can be further hydrolyzed by prolonged cooking in the same solvent mixture using a low degree of polymerization powder or sugar or lignocellulosic material Dehydration and degradation products of sugars such as furfurals and organic acids. The recovered lignin and sugar are useful as raw materials in the phenolic, sugar and sugar fermentation industries.

'Method according to the invention is carried out such that comminuted lignocellulose with a predominant proportion by 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, the G _r uppen water-soluble low molecular weight aliphatic alcohols and water-soluble low molecular weight aliphatic ketones and mixtures thereof, wherein the solubility parameter of the chosen liquid organic solvent is in the range of 10 to 13, and an acid hydrolyzing catalyst in such amount that the pH of the solvent mixture is in the range of 1.7 to 3.5; wherein the acidic catalyst from the group of organic acids oxalic, maleic, o-phthalic, L-apple, succinic, nicotinic, salicylic and trifluoroacetic, from the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid and from the G impregnated with the neutral buffering salts, impregnating the impregnated lignocellulose with the delignifying and saccharifying action of

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at a temperature in the range of 160 to 210 ° C for a time of at least 3 minutes and for a time sufficient to render the fibers separable from fluidized cellulose residue by fluid movement, then stripping the cooking liquor of the cellulose residue Solvent from the mentioned groups of organic liquid solvent washes and the residue is then washed with water.

The liquid organic solvent in the solvent mixture as well as the liquid washing solvent may according to the invention be acetone or ethanol.

Preferably, the liquid organic solvent may be ethanol and the hydrolyzing acid catalyst may be oxalic acid, maleic acid, o-phthalic acid, L-malic acid, succinic acid, nicotinic acid, salicylic acid, trifluoroacetic acid or a mixture of potassium chloride and hydrochloric acid.

However, the liquid organic solvent may also be acetone and the acidic hydrolyzing catalyst may be hydrochloric acid.

The process of the present invention is further carried out by evaporating the low-boiling volatiles in the stripped cooking liquor and wash solvent to precipitate lignin, separating the lignin from aqueous sugar solution, re-dissolving the separated lignin in a lignin solvent to saturation, and Ligninlösung is spray-dried or mixed with a predominant volume of water to a precipitate of finely divided lignin to disper- '

yaw".

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In this case, the lignin solvent is selected for example from the group of liquid organic solvents of acetone, furfural, dimethyl sulfoxide or tetrahydrofuran.

The aqueous sugar solution is concentrated according to the invention by stripping of steam to a content of dissolved pesticides of 20 to 50 % .

However, in the present invention, the volatile materials may also be separated by fractional distillation to recover the liquid organic solvent and the liquid washing solvent and to add volatile thermal conversion products and volatile hydrolysis products, namely, methanol, formic acid and acetic acid. win.

It should be noted that the volatile materials removed by steam stripping are fractionally condensed according to their boiling points. the liquid organic solvents, the liquid washing solvent and the volatile thermal conversion products, and the volatile hydrolysis products, namely methanol, furfural, 5-hydroxymethylfurfural, levulinic acid, formic acid and acetic acid.

After this. According to the invention, the acidified solvent mixture is mixed with the lignocellulose in a blend ratio between 1: 4 and 1:12.

In particular, the acidified aqueous organic solvent mixture is mixed with comminuted lignocellulose in a pressure vessel with inlet and outlet and the solvent mixture continuously through the lignocellulose

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circulated so that the residence time of the cooking liquor is not longer than 5 minutes, after which the liquid is withdrawn while fresh solvent is mixed in to replace the withdrawn mixture.

In this case, the lignocellulose and the Lösungsmitbelgemisch are moved toward the outlet ν, / earth, wherein the solvent mixture is moved at a higher speed than the lignocellulose.

The process according to the invention can be further carried out by mixing particles of the whole lignocellulose with a predominant volume fraction of a first hot aqueous acidified organic solvent mixture of 40 to 60 parts, 60 to 40 parts of a liquid organic solvent of the group ethanol and acetone and a first hydrolyzing acidic catalyst in such an amount that the pH of the solvent mixture is in the range of 3 * 5 to 1.7, from the group of the organic acids maleic, oxalic, o-phthalic, L-apple, amber, nicotinic, salicylic and trifluoroacetic acid, exposing the impregnated lignocellulose to the delignifying and saccharifying solution of this first solvent mixture at a temperature of about 180 ° G and for a time of about 5 minutes, then withdrawing the cooking fluid from the partially delignified lignocellulose, then with the partially delignified residue a second aqueous acidified organic solvent mixture comprising a second acid hydrolyzing catalyst from the group of inorganic acids, from which the first acid hydrolyzing catalyst

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was chosen, at a second digestion temperature of not more than 210 ° C and close to 200 ° C for a long time to make the fibers separable by liquid movement, boiled, then the second cooking liquor, the cellulose residue washed with acetone and then the residue with water washes to obtain a pulp of cellulose fibers of high degree of polymerization.

In this case, the first and the second acid hydrolyzing catalyst may be oxalic acid and the organic solvent may be ethanol.

In particular, the process is carried out by mixing the first and second aqueous-organic solvent mixture with the lignocellulosic particles in a pressure vessel with inlet and outlet and circulating the solvent mixture continuously through the lignocellulose, with first and second solvent mixtures together with the lignocellulose towards the outlet is moved through the container and the speed of movement of each mixture is greater than the speed of movement of the lignocellulose, and further such that each of the volatiles present in the withdrawn cooking liquids and the washing solvent is evaporated to precipitate the lignin dissolved therein; the lignin is separated from aqueous sugar solution, the separated lignin to the. Saturation in a lignin solvent is redissolved and the lignin solution is spray dried or mixed with a substantial volume of water to disperse precipitated fine lignin.

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In this case, according to the invention, the aqueous sugar solution obtained from the withdrawn first solvent mixture is concentrated to a solids content of from 20 to 50% , likewise the aqueous sugar solution obtained from the second solvent mixture.

According to the invention, the solvent for the lignin acetone obtained from the first solvent mixture and the solvent for the lignin obtained from the second solvent mixture from the group acetone, furfural, dimethyl sulfoxide and tetrahydrofuran are selected.

The invention further relates to a method for separating the fibers from the cellulose component of lignocellulose and recovering the fibers in a state of reduced degree of polymerization. It is carried out by mixing particles of the whole lignocellulose with a major volume fraction of 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 of the group of volatile water-soluble organic solvents Ethanol and acetone and a first acid hydrolysis catalyst in such an amount that the pH of the solvent mixture is in the range 3.5 to 1.7, from the group of organic acids maleic, oxalic, o-phthalic, organic Impregnated apple, succinic, nicotinic, salicylic and trifluoroacetic acid, the impregnated lignocellulose the delignifying and saccharifying effect of the first solvent mixture at a temperature of about 180 ⁰ O for a period of about 5 minutes exposing, then the first

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Extracting cooking liquid from the teilentlignifizierten lignocellulose, then the teilentlignifizierten lignocellulosic residue with a major volume fraction, based on this residue on a second aqueous acidified organic solvent mixture containing a second acidic hydrolyzing catalyst from the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid a digestion temperature in the range of 180 to 200 ^° C for a time sufficient to cause partial saccharification of glucan and release cellulose fiber of low degree of polymerization, "boil", then stripping off the second cooking liquor and washing the residue with water.

This variant is carried out such that the first organic solvent is ethanol and the second solvent mixture contains either ethanol or acetone, the acidified aqueous organic solvent mixtures in a pressure vessel with inlet and outlet mixed with the lignocellulose and each of the solvent mixtures during the cooking time continuously through the lignocellulose the first solvent mixture is circulated parallel to the lignocellulose in the direction of zunkuslaß at a rate greater than that of the movement of the lignocellulose and the second solvent mixture is moved countercurrently to the movement of the lignocellulosic residue and further such that the low boiling volatiles in each of the stripped cooking fluids and wash solvent are evaporated to precipitate lignin, the lignin is removed from the aqueous sugar

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solution is separated, the separated lignin is dissolved in a lignin solvent to saturation again and the Llgninlösung is spray-dried or mixed with a predominant volume of water to disperse a precipitate of finely divided lignin · Here again from dsia first solvent mixture obtained aqueous sugar solution concentrated to a solids content of Hemicelluloseumwandlungszukkern from 20 to 50 % and concentrated from the withdrawn second solvent mixture aqueous sugar solution to a pesticide content of 20 to 50 % concentrated »

The solvent is for the recovered from the first solvent mixture lignin acetone and the solvent for the recovered from the second solvent mixture lignin from the group acetone, furfural, dimethyl sulfoxide and tetrahydrofuran gevi / ·

In a further variant, the invention relates to a process for separating the fibers from the cellulose constituent of lignocellulose and obtaining a microcrystalline residue from these fibers It is carried out by acidifying all the comminuted lignocellulose with a major volume fraction of a first hot aqueous one organic solvent mixture from 40 to 60 T _e ilen water, 60 to 40 parts of a first organic solvent from the group of the volatile water-soluble organic Lösungsmitbei ethanol and acetone, and a first acidic Hydrolysierungskatalysator in such an amount that the solvent mixture contains a pH in the range of 3 » 5 to 1.7 has, from the group

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the organic acids maleic, o-phthalic, oxalic, L-apple, succinic, nicotinic, salicylic and trifluoroacetic acid impregnated, the impregnated lignocellulose of the delignifying and saccharifying action of the first solvent mixture at a temperature of about 180 ⁰ C. for a period of about 5 minutes, then the first cooking liquor is withdrawn from the partially delignified lignocellulose "thereafter this teilentlignifizierten residue with a major volume fraction, based on the residue, of a second aqueous acidified organic solvent mixture containing a second acidic hydrolyzing catalyst from the group hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid at a digestion temperature of 200 to 210 ⁰ C for a sufficiently long time to hydrolyze the cellulose boils, so that the fiber structure is degraded into the crystalline region of non-fiber form and absence of amorphous polyglucose, then the zw Remove cooking liquid and wash the microcrystalline residue with water.

In this case γ / ird become so barred 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 the direction parallel with the lignocellulose and at a rate greater than that of the lignocellulose through which lignocellulose is circulated and the second solvent mixture is continuously circulated countercurrently through the partially delignified lignocellulose

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and further such that the present in o ^e <3.er withdrawn cooking liquor and in the wash solvent, low-boiling volatiles are evaporated in order to precipitate the lignin, the lignin is separated from the aqueous sugar solution, the separated lignin up. is redissolved to saturation in a lignin solvent and the lignin solution. spray-dried or mixed with a predominant volume of water to disperse a precipitate of finely divided lignin.

The solvent for lignin separated from the first solvent mixture is "acetone and the lignin solvent separated from the second solvent mixture is acetone, furfural, di-methyl sulfoxide or tetrahydrofuran.

In accordance with the present invention, further, the above-mentioned volatile materials are separated by fractional distillation to recover organic liquid solvents and volatile thermal conversion products and volatile hydrolysis products including methanol, formic acid and acetic acid.

The aqueous sugar solution recovered from the withdrawn first solvent mixture is again concentrated to a solids content of hemicellulose conversion sugars of 20 to 50 % .

It can also be moved so that the aqueous sugar solution by steam stripping up to a G _e hold

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is concentrated to 20 to 50 % dissolved pesticides and the volatiles are fractionally condensed in the vapor phase to recover the organic liquid solvent and the volatile thermal conversion products of the hydrolysis.

Furthermore, the invention relates to a method for separating the fibers from the cellulose component of lignocellulose and recovering lignin and hydrolysis products of hemicellulose and cellulose. It is carried out such that the whole comminuted lignocellulose with a major volume fraction of a first hot aqueous acidified organic solvent mixture of 70 to 30 parts of water, 30 to 70 parts of an organic solvent of the group ethanol and acetone and a hydrolyzing acid catalyst in a sufficient amount to impart a pH in the range of 3.5 to 2.2 to the solvent mixture, from the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid impregnated, the impregnated lignocellulose at a temperature of about 180 ⁰ C and for a time of about 5 minutes sufficient to liberate the cellulose fibers, subjecting to the delignifying and saccharifying action of the solvent mixture, then stripping off the first cooking liquor and mixing the lignocellulosic residue with fresh aqueous acidified organic solvent mixture which coats the first solvent mixture CHT except that the second solvent mixture has a higher concentration of acid, namely a pH range of 2.2 to 1.7, mixed, and the G _e mixture at a temperature of about 210 ⁰ C and for a Removing

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sufficient time to almost completely dissolve the cellulose, then boil the second cooking liquid which vaporizes the low-boiling volatile materials present in each cooking liquor to precipitate lignin, which separates lignin from the liquors, leaving a residual liquid, the sugar and containing other conversion products, recover the condensed volatile materials and separate the dissolved sugars and other conversion products from each of the residual liquids.

Lignocellulose and cooking liquid are used in the ratio of etvja 1:12 ·

The invention also relates to a process for the conversion of lignocellulose to hydrolysis and dehydration products of lignin, hemicellulose and cellulose, including furfurals, organic acids, acids, methanol and residual sugars. The procedure is that of crushing structured vegetable matter having a major volume fraction of a hot aqueous acidified organic solvent mixture of 70 to 30 parts HpO, 30 to 70 parts of a liquid volatile organic solvent having a solubility parameter in the range of 10 to 13 A group of water-soluble low molecular weight aliphatic alcohols and low molecular weight aliphatic ketones and mixtures thereof and an acid hydrolysis catalyst of the group of 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 3.5 to 1, 7, at a temperature of about 210 ⁰ C and for a time sufficient to saccharify virtually all glucan and practical

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convert all sugars formed by the hydrolysis in their dehydration and degradation products, impregnated, then volatile components of the cooking liquid with a vapor phase in the temperature range of 50 to 250 ⁰ C evaporating and separating the volatile materials by fractional distillation, and sugars and lignin of wins the backlog «

The liquid organic solvent is acetone, and the weight ratio of lignocellulose to cooking liquor is initially about 1:12.

In a further embodiment, the process according to the invention for separating the fibers of the cellulose end-fraction from lignocellulose is carried out by dissolving the whole comminuted lignocellulose with a major volume of a hot aqueous acidified organic solvent mixture of 70-30 parts water, 30-70 parts volatile liquid organic solvents having a solubility parameter in the range of 10 to 13 from the groups of the water-soluble low molecular weight aliphatic alcohols and the water-soluble low molecular weight aliphatic ketones and mixtures thereof and a hydrolyzing catalyst selected from the group consisting of organic acids _, maleic, oxalic, o-phthalic , L-apple, amber, nicotinic, salicylic and trifluoroacetic acid in such an amount that the pH of the solvent mixture is in the range of 3.5 to 1.7, the impregnated lignocellulose is impregnated at a temperature in the range of 160 bi s about 180 ⁰ C for a sufficient time to dissolve the greater part of the hemicellulose and the greater part of the lignin, so

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that the fibers are not yet released after cooking but can be released by vigorous mechanical agitation of an aqueous suspension of the lignocellulose residue, then the cooking liquid is stripped off the residue, the residue is boiled with acetone and then washed with water, the residue in water dispersed and the dispersed residue under high pressure to obtain a mechanical pulp of high strength.

In this case, the liquid organic solvent is ethanol or acetone and the liquid washing solvent is acetone. In this embodiment, the lignocellulose is subjected to the delignifying and saccharifying action of the solvent for a period of not more than 5 minutes.

In a further inventive variant of the method for separating the fibers from the cellulose content of lignocellulose is moved so that the janze crushed lignocellulose with a major volume fraction of a hot aqueous oig anic acidified solvent mixture of 70 to 30 parts of water, 30 to 70 parts of a liquid volatile organic solvents from the groups of the water-soluble low-molecular-weight aliphatic alcohols and the water-soluble low molecular weight aliphatic ketones and mixtures thereof whose solubility parameter is in the range of 10 to 13, and an acid hydrolyzing catalyst of the group of the strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid and the group of with

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strong acids buffered to their neutral salts in such an amount that the pH of the solvent mixture is adjusted in the range of 3.5 to 1.7, the impregnated lignocellulose impregnates the delignifying and saccharifying action of the solvent mixture at a temperature in the range of about 130 to about 180 C for a time sufficient to cause dissolution of the major part of the hemicellulose and the major part of the lignin, so that the fibers are not yet released after cooking, but by vigorous mechanical agitation of an aqueous suspension of the lignocellulose residue then the cooking liquor is stripped off the cellulosic residue, 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 high strength mechanical pulp and further such that di e lignocellulose and the acidified aqueous-organic solvent mixture are introduced with mixing in a pressure vessel with inlet and outlet in a weight ratio between 1: 4 and 1:12 and fed together in the direction of the outlet through the container, wherein the speed of movement of the solvent mixture greater is the one of the movement of lignocellulose. The lignocellulose is exposed to the delignifying and saccharifying action of the solvent mixture for a period of not more than 5 minutes.

The invention further relates to a continuous process for releasing the fibers from the cellulose component of lignocellulose. It is executed in the way

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that he

Introducing particles of lignocellulose through an inlet into a first pressure vessel, said first vessel having at least one inlet and at least one outlet spaced from said inlet at a distance along the length of the vessel and capable of maintaining its content under elevated pressure, introduces,

by 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 Hydrolysierungskatalysators in such M _e length that the pH of the mixture in the range of 1.7 to 3 »is set 5, Tiobei the liquid organic solvent from the group of water-soluble low molecular weight aliphatic alcohols and the group of water-soluble low molecular weight aliphatic ketones and mixtures thereof whose solubility parameter is in the range of 10 to 13, is introduced,

1 selects and supplies heat to the reservoir to keep its contents at a temperature of at least 160 ° C but not exceeding 210 ⁰ G, while lignocellulose and solvent mixture in direction: a weight ratio of introduced solvent to feed at least A- - moved to the outlet through the container,

circulating the solvent mixture so that its velocity is considerably greater than the speed of the comminuted lignocellulose, and withdrawing solvent mixture containing lignin and sugar dissolved through an outlet to limit the residence time to a certain value,

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withdrawing lignocellulosic residue and impregnating solvent from an outlet of this first container without reducing pressure,

Separating solvent mixture from the withdrawn lignocellulosic residue until only a small volume fraction of liquid remains in the lignocellulosic portion, transferring the lignocellulosic residue through an inlet to a second pressure vessel, said second vessel having at least one inlet and one outlet spaced along the length of the second can be arranged container from each other, and having to maintain its contents under pressure, introduces a second aqueous acidified solution-smittelgemisch of 70 to 30 to 70 parts of a liquid volatile water-soluble organic solvent and an acidic Hydrolysierungskatalysator sufficiently M length _e to the pH of the mixture in the range of 1.7 to 3 * 5, wherein the liquid organic solvent is selected from the group of water-soluble low molecular weight aliphatic alcohols and the water-soluble low molecular weight aliphatic ketones and mixtures thereof, whose solubility parameter is in the range of 13 to 13, a ratio by weight of solvent mixture to lignocellulosic residue entering the second pressure vessel in the range of 10: 1 to 4: 1, and supplying heat to the contents such that a temperature close to 210 ^° C., but not above, while "passing the lignocellulosic residue and the solvent mixture towards the outlet, allowing the second solvent mixture to flow through the second container and mixing solvent mixture under

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deducting a given residence time from an outlet,.

Lignocellulosic residue passes through the second container at such a rate that the cooked particles are discharged from an outlet in such a state that the cellulose particles are freely separable.

withdrawing the impregnating solvent mixture and dissolved lignin and sugar-containing particles from the second container without lowering the pressure,

Remove solvent mixture from the cooked residue,

- the cellulose residue is extracted and washed successively with washing liquid of pure organic solvent and then liquid aqueous organic solvent and then with water, and

- The solvent-extracted washed cellulose fiber mass performs _c

In particular, it will be appreciated that the first withdrawn solvent mixture is distilled at a noncoking temperature to separate volatile materials and precipitate lignin in a syrupy residue, condensing the volatile materials to recover the liquid organic solvent, and the recovered liquid organic solvent is used again in the process, wherein also the withdrawn second. Is subjected to distillation at non-coking temperature to separate volatile materials and precipitate dissolved residual lignin, condensing the volatile materials to recover the liquid organic solvent.

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win, and the sugar and dehydration products containing liquid residue is recovered.

The continuous process is advantageously carried out in such a way that the acid hydrolysis catalyst contained in the first or the second solvent mixture is selected from the group of the 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. The boiling temperature in the first container is about 180 ° C and the cooking temperature zvjeiten in the container about 210 ⁰ C, wherein, the pH of the first solvent mixture is in the range of 1.7 to 2.2.

The continuous process is characterized in particular by the fact that the liquid organic solvent in the first solvent mixture is ethanol or acetone and is mixed with a similar content of water, the acid hydrolyzing catalyst for the first solvent mixture from the group of the acids oxalic, maleic -, o-phthalic-> L-apple, succinic, nicotinic, salicylic and iPrifluoressigsäure and mixtures of a neutral buffer salt of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid in admixture with the corresponding strong acid is chosen so that the pH of the Solvent mixture is adjusted in the range of 1.7 to 2.2, the liquid organic solvent for the second solvent mixture is acetone, with the V / asser in the ratio of 4-0 to 60 parts by volume

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Acetone is mixed to 50 to 40 parts by volume of water, and the Gewichtsverhätätnis of lignocellulose to solvent mixture between 1: 4 · and 1:10 is set, and that used for the second solvent mixture acid hydrolyzing catalyst from the group of strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid is selected ·

Particularly advantageous is the implementation of the continuous process, wherein the cooking of the lignocellulosic residue is continued in the second pressure vessel until a partial saccharification of glucan and a virtually complete fiber release have occurred by breaking the microfibrils into crystalline particles without fiber structure and by the absence of amorphous polyglucose and in that the solvent-extracted and washed Celluloserüokstand is dehydrated to a substantially anhydrous cellulose powder.

The invention also relates to a continuous process for the delignification of lignocellulose and virtually complete conversion of the glucan into sugar dehydration and degradation products which is carried out in such a way that

- introduce comminuted lignocellulose through an inlet into a pressure vessel, said vessel having at least one pair of inlet and outlet at each end for the introduction and discharge of materials and capable of holding its contents under elevated pressure,

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an acidified aqueous organic Lösungsmitfcelgemisch from 30 to 70 parts of water, 70 to 30 parts of a water-soluble organic solvent, the G _r oup acetone and ethanol and an acid of the group of strong acids hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid in such an amount that the pH of the Is set in the range of 1.7 to 3 »5," selects, introduces,

a ratio of feed to solvent mixture of 1 part lignocellulose to 10 to 15 parts solvent mixture complies,

heat is added to the contents of the container so that its temperature is about 210 ^° C. while the comminuted lignocellulose is moved towards the outlet at a distance from the inlet while allowing solvent to circulate in countercurrent to the direction in which the lignocellulosic material passes through,. Solvent mixture containing lignin and sugar dissolved, withdrawn from an outlet near the inlet and feeding fresh heated solvent mixture through an inlet remote from that inlet,

distilled solvent mixture at Mchtverkokungstemperatur distilled to recover the ethanol or acetone as a condensate and precipitate the lignin from a • syrupy residue, and introduces the syrupy residue with the condensate through the second, from the first remote inlet,

the lignocellulose is exposed to the saccharification effect of the solvent mixture for so long that there is virtually no solid organic residue removed from the inlet

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Reached outlet and so long that the dissolved products formed from cellulose to furfurals of pentoses and

Hexoses are dehydrated, subjected, and - a liquid containing the sugar dehydration products withdrawn.

B _e i of this process variant, the distillation is carried out at such a temperature that the volatile organic compounds autolytic produced methanol, 2-furaldehyde and 5-hydroxymethyl-2-furaldehyde, and the present in lignocellulosic organic acids and the acids acetic autolytic generated formic sensäur e $ Lactic acid, levulinic acid, placatinic acid, tannic acid, tartaric acid and oxalic acid remain in the syrupy residue *

The invention is an improvement of the known organic solvent-releasing processes of the cellulose fiber and consists in an optimum combination of liquid organic solvent mixed with water which is excellent in penetrating hemicellulose ind-lignin and bringing into its presence the acidic catalytic compound so that the acidic mixture can rapidly hydrolyze lignin and hemicellulose and dissolve the hydrolysis products with the release of a high strength cellulosic fiber. It has been found that a mixture of a liquid, volatile, water-soluble organic solvent having 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

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- 27 -

2 »33» is acidified to a pH in the range of 3 »5 to 1.7 by the addition of a particular hydrolytic catalyst, penetrates rapidly into lignocellulose, and degrades lignin and hemicellulose to their low molecular weights or monomers without the degree of polymerisation of the cellulose fiber considerably reduce. The delignification and saccharification in bulk can be performed to any desired degree by lengthening the wedding, which may be up to 5 minutes to set aspen fibers at liberty, or up to 1 hour or less to wood up to a residual solids content of only 1 %

Hardwoods, softwoods and agricultural lignocellulosic material, such as straw, bagasse, grass and bamboo are, contains dissolved rapidly DispeisLonen of fibrous material in a liquid, the sugars and lignin, transferred, when ⁰ C with, for example, ethanol or acetone at about 180 to 200 the organic solvent and hydrochloric acid or oxalic acid as the acid catalyzing compound dissolved in the mixed solvent. As described in more detail below, however, other solvents and acid catalysts according to the invention can also be used for separating off the cellulose fibers. become.

According to the invention, a Eochflüssigkeit is applied, with the extremely rapid cellulose fibers can be separated in a relatively undegraded state.

According to the invention, a new, an acidic

207 5

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- 28 · - ·. ·.

Catalyst-containing hydrolyzing solvent mixture used which is inexpensive and can be obtained for a process in single 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.

According to the invention, a cooking liquid is used which can be used either to separate cellulose fibers or to saccharify lignocellulose to a desired degree, including practically complete dissolution of the wood.

The composition of the solvent mixtures is particularly important for their effect on the components of lignocellulose,

As is known, the accessibility of the cellulose in lignocellulose for the cooking liquid initially depends on the ability of the solvents to swell and dissolve the lignin, particularly the high molecular weight lignins present in the cell wall layers. It is also known that the solvent lignin solvent solubility and solubility 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 is given for example by "Solubility of Non-Electrolytes" by J.H. Hildebrand and R, L. Scott, 1951. Edition III, Reinhold Pusblishing Company, New York, especially Chapter X. The lignin solubility is described in the article by CH. O.shuer, "Solvent Properties of Lignin and

- 29 -

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- 29 * -

Their Relation to Solubility, Swelling, Isolation and Production of Lignin ", Ind. & Eng., 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 (CEUOD) is proportional to the hydrogen bonding capacity of the solvent. For the best lignin solubility, a shift of 0.14 units has been found to be optimal. Values below this value indicate moderate or poor lignin solvents. As can be seen from Table I, which summarizes the solubility parameters and deuterium shifts for some organic liquid solvents, the solubility of lignin is limited to solvents having a solubility parameter in a narrow range, generally between about 10 and 13 units

these are arbitrary numerical values that are assigned to vapor pressure measurements and correspond to an optimal infrared shift for -OH OD of 0.14.

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- 30 -

Table I

Solvent medium Solubility parameter 9.3 Deuterium shift Solubility of the originally present lignin ether 10.0 0.19 insoluble Methyläthyl- • 10.0 ketone 10.7 0.11 partially soluble dioxane 10.8 0.14 soluble acetone 12.7 0.14 soluble pyridine 14.2 0.27 soluble Methyl cellulose 16.5 over 0.4 soluble ethanol 23.4 over 0.4 soluble Ethylene glycol • 0.31 soluble glycerin over 0.4 insoluble water over 0.4 insoluble

Veinser is known to have limited solubility for certain lignins and is able to dissolve mainly monomeric units of a polar nature. Lignins of moderate to low molecular weight are capable of dissolving in the lower molecular weight aliphatic alcohols, while dioxane, acetone and pyridine are excellent solvents for all molecular sizes present in lignin preparations obtained by mild extraction methods

have proved.

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to /

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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 greater than in the pure liquid solvent alone. This effect is particularly strong for mixtures containing water and ethanol or Dioxane, but most impressively in mixtures of acetone and water, which, when the constituents are present in nearly equal quantities, penetrate extremely rapidly into lignocellulose.

It has further been found that the improved lignin solubility of the solvent in admixture with water can be related to improved hydrogen bonding capacity over either pure water or pure liquid solvent. of the mixture. The improved hydrogen bonding capacity results from the phenomenon of volume reduction of a mixture of equal volume of ethanol or acetone and water and in particular from the strong evolution of air bubbles and the turbidity of a mixture of ethanol or acetone with acidified water containing dissolved gases from the ¹ air. The volume shrinkage at Vennich's equal volumes of acetone and water is about M%, for equal volumes of ethanol and V / a 2 % _t, indicating different cohesive energy densities.

Line effective hydrolysis of lignocellulose is achieved when the mixing ratio of organic liquid solvent to water in the range of about 30 to

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Divide solvent to 70 to 30 parts of water. Since during a cooking process the simultaneously hydrolyzed sugars and lignins must be taken up by the common solvent mixture, the solvent mixture must be used in excess, usually in an amount of from A to 12 times the wood weight, and a sufficient amount of water, especially during the later stages of cooking, during which the carbohydrate dissolving power of the solution becomes critical, to be present in order to solubilize the sugars, which are largely insoluble in the organic solvent. When the fiber separation in two successive stages, in which different Solvent mixtures are used, for the first solvent used generally higher ratios of organic solvent to water are advantageous to take up the lignins, while, during the later stage, when the hydrolysis to the dissolution of residual Hemicellulose and glucan is limited, lower ratios of liquid solvent to water are preferred to accommodate the higher levels of hydrolyzed sugars.

The solvent mixture also has a considerable influence on the adjustment of the ionic strength and the dissociation of the acidic catalyst dissolved in the mixture. For example, various hydrolyzing capabilities may result when an aqueous amphiprotic solvent of water and ethanol or an aqueous aprotic solvent mixture such as water and acetone are charged with equal amounts of a particular acidic catalyst

- 33 -

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be mixed. Such a difference can be advantageously used in such a way that the speed of hydrolysis is accelerated during the initial boiling, while at the end of a cooking process the least possible action on the cellulose is desired so that non-precipitated high purity fibers of the solvent mixture are mixed Freedom be set.

The influence of acidified cooking liquors on the hydrolysis of the lignocellulose microstructure will be explained in more detail below.

Solvent mixtures of water and an organic solvent such as icone, ethanol or dioxane, containing an acidic compound dissolved and having a pH of only 1.7 ', allow the hydrolysis to proceed through all impregnated zones of the lignocellulosic structure. The coexistence of protons from the dissociated acid and liquid solvent promotes penetration of the cell wall layers and differential sources of the constituents so that soluble hydrolysis products rapidly absorbed by the fluid are formed. Although of course all acids may be proton donors, has shown that various acids, when dissolved in the aqueous solvent mixture possess different fiber separation capability · So some acids have-even at a temperature above 200 ⁰ C, virtually no fiber separation capacity, while other acids very have different effects, so that only a relatively small number of acids has been found to be practical.

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Mild hydrolyzing catalysts are generally suitable for making pulps for papermaking, while a high purity cellulose, albeit of lesser degree of polymerization - hereinafter "DP" - is best obtained using strong acids in the solvent mixture, with strong acids then being required are when complete saccharification is to be achieved. It could have been expected "that strong acids with high dissociation constants, i. H. close to uniformity, faster and stronger hydrolyzing agents than complex acids and organic acids with low dissociation constants. However, these expectations are not met by the acidified solvent mixtures.

Acidivity is a macroscopic property that indicates the ability of the solution to provide protons for base reaction or for the adjustment of a charge transfer process, and is based on measurements based on conventional single ion activities, such as determinations of pH , the dissociation constant and the pK values. Acidity is most accurately represented by the single electrode potentials. ,

The ionic strength is usually quite close to ionization entropy, 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 solution reactions, the effects of

- 35 .-

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- 35 -

be considered solvents, because interactions between solvent and ions, the mobility of the ions, the ion potential and the kinetic energy of the ions are modified.

The electrostatic hydrogen bonding 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 solvated anions, thereby also reducing the ionization constant the acid is lowered. However, there have been strong differences from the expected ionization constant changes in both aqueous amphiprotic solvents such as ethanol / water characterized by hydrogen bonding and in aqueous aprotic solvents such as acetone / water characterized by the absence of hydrogen bonding , detected. It has been found that the ionic conductivities of the acids vary very irregularly with a change in the solvents, 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.

If aqueous-alcoholic solutions containing

- 36 -

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- 36 -.

50% ethanol or more were mixed with various acids, the acid dissociation, although many of the solutions had constant concentrations of the acids in question, was very different. In contrast, the conductivities of water / acid mixtures were almost equal. The anomalies were greatest in weak acids, since strong acids are leveled, ie converted into the acidic species in aqueous solutions. It is known that weak acids do not completely dissociate, and the acidity of the organic solvent itself, ie its hydrogen bonding capacity, determines which proteolytic reaction takes place between the solute and the solvent. Because of the unequal solvation of various anions, the relative strength of acids in solvent mixtures is largely dependent on the organic solvent chosen.

Amphipotise solvents have good proton stability because free protons are hardly available because of their combination with some species of solute / solvent which 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 are used. have the same autoprotolytic constant, namely dissociation or ion product constants, very different effects on the acid behavior of such solvents are observed. This is due to the fact that the interactions between ions and solvent are usually stronger than the interactions between

- 37 -

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the uncharged particles, which causes solvations of the respective acid anions in the different solvent systems to become uneven. Since different acid / base equilibria occur, the acid strengths depend on the nature of the solvent system. These effects may be taken into account when an acidic additive is chosen for a solvent mixture of desired hydrolyzing properties, for example when the hydrolyzing capacity is sufficient to degrade hemicellulose to sugars, but is insufficient to attack the glucan.

The experimental selection of an acid for a solvent mixture which is to have a certain hydrolyzability must first take into account its dissociation constant or its pK. value in water. However, this does not necessarily indicate its 'catalytic' effect with respect to the release of the Paser, since weak acids with the same charge type and almost identical dissociation constants are not only. behave differently in a particular aqueous / organic solvent mixture of constant composition but also change its behavior when an aprotic solvent such as acetone is used instead of an amphiprotic solvent such as ethanol. It was found by experiments that at the same concentrations of solvent / 1 water / acid acetone the dissociation decreased further by 25 % 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 than

- 38 -

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AP C 13 K / 207

usually found in hydroxylic solvents.

Since the ionic strength of acids is differently influenced by the proton release _{g 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 mean effect on the hydrogen ion is measured directly as a rough measure, although it is clear that that the hydrogen electrode potential and the stability are considerably dependent on the solvent system. The pH and conductivity values summarized in Table II illustrate the above relationships,

- 39 -

table

II

pH and. Conductivity of the solvents, solvent mixtures and the acidified

cooking liquid

oxalic acid

buffered acid *

0,025

0.05

0.10

2.05 4.0 1.82 7.0 1.65 11.9

2.69 2.50 2.36

1.93 ^{; i} 6.3

2.26 1.52 0.97

hydrolyzing Säurekon water 0.84 ^S3 Single solvent Iceton VJJ VO the acidic catalyst concentration, molarity Cond. pH mrnho ethyl alcohol Cond. pH mmho I 6.4 9.7 Cond. pH mmho 6,96 '0,04 ³ ^ 0 2.2 '11.0 * 5.85 O, O5 ^S55 0.01 1.96 37.0 -500 7,3 ^ ³⁵ HCl 0.025 · 1.75 .2.0 215 ^SS -520. 9.8 ^HH 0.05 1.1 1,50 398 ⁵ ^ -518 31.2 ^ ³⁵ mv 0.10 1.45 0.66

te v

VjO

ΓΌ O -O

VJl CO

σ "

Table II- Continued

pH and conductivity of the solvents., Solvent mixture and the acidified

Cooking liquid · '

Hydrolyzing acidic catalyst

Acid concentration, molarity

Solvent emisch

Athylalk.:H~O 60:40 ^

Ethyl alk. : 3 50:50 acetone: H _o 0 60:40 ^d

Acetone:! 50:50

Cond. pH mmh

Conductivity pH mmho

Cond.

pH mmho

Cond. ptl mmho

0 0.01

0,025

0.05

0.10

5.35 29.9

2.35 2.06

1.81

0.54 1.04 2.00

4.85 2.50 2.34 2.02 1.76

3; SS.

5 ", 9O ^{0,21 ÄÄ} 4,26 0,41

0.67 2.25 0.70 1.32 2.01 1.26 2.52 1.77 2.48

2.15 1.62 2.05 0.84 1.75 3.18

oxalic acid

0.025 0.05

0.10

2.58 0.58 2.52 0.89 2.37

2.37-1.48 2.29 1 | 65 2.18

2.20 1.46 2.09 3.61 2.01

-59.90

2, '13 1,1 2,16, 74

1.93 1.69

buffered acid

2.05 4.15

2.03 4.70 3.19 3.08 1.96 3.45

2S buffer: (25 ml 0.2m KCl + 6.5 ml 0.2m HCl) diluted to 400 ml for 60:40 and to 500 ml for 50:50 "

S3? The values marked in this way are micromho and not millimho.

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- 41 -

The data show that high solvent / water ratios favoring solubilization of lignin give lower conductivities for strong acids such as H 2 O, as well as for weak acids such as oxalic acid at 60:40 ratios for both ethanol / water and water for acetone / water mixtures compared to acid / water mixtures of equal molarity.

In general it can be stated that in the case of dicarboxylic acids in which the group -COOH are closer together, the effect of the admixture of alcohol on the pKa value for the first dissociation is greater than for the second. This effect is less pronounced for acids in which the groups -COOH are further apart. The activity factor is less affected by the addition of alcohol to undissociated molecules than to the ions of the ions.

If solvent mixtures are mixed with acids which must be present in a molarity above 0.025 to 0.05 in order to adjust the pH to 2.5 or below, the effect of the mixture is moderate with respect to the separation of cellulose fiber from lignocellulose. because these acids require long cooking times and / or high acid concentrations and thus high energy consumption and lead to extreme depolymerization of the cellulose. Table IH are for a number of organic mono- and dicarboxylic acids, the Entlignifiziervermögen at a molar concentration of 0.05 in an ethanol / water mixture of 60:40 at 200 ⁰ C, the related kappa fourth and the residual content of lignin on the fibers , the degree of Faserabtren * tion and the TAPPI viscosity, the degree of polymerization

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 ~ 42 -

the fiber indicates * indicated. Pichten lignocellulose with a chlorite-holocellulose content of 77i5 % was used. It can be seen that, unless fiber separation occurred at 30 minutes, an insufficiently low pH of the cooking liquor was generally a contributory factor, although exceptions can be seen in the case of monochloroacetic and trichloroacetic acids.

Table III

Sttlignification capacity of organic, acid-catalyzed solvent mixtures

^y Organic First Disso- First ionic-pH of the solution-cooking-acid cation constellation pK ,, telemic time

«4-« ^. 4-λ -Ϊ «TTΓ \TT/ ~ \ fZ Γ \ (Τ?  "· _...." J3_A «-._Al

constant in H ₉ OH ₉ O, 60 % * * alcohol

before after the min. Cooking cooking

Yield Kappaan pulp number / % residual lignin

DP

TAPPI

viscosity

Ants acid 1.77 χ ₁₀ -4 3.75 / 5.01 2.2 3.5 30. 77.5® KFT * 1.27 1220 I Acetic acid 1.76 χ 10-3 4.75 / 6.29 2.9 3.5 30 " KFT - - VJJ I oxalic acid 5.9 χ 6.4 χ 10 "" ⁵ 1.23 / 2.52 2.05 3.2 10 20 67 120/15/6 79 / 10,3 1050 950 L-apple acid 3.9 χ 7.8 χ 10 " ⁶ - • 2.68 4.1 30 56 95 / 12.4 895 Q Maleic acid 1.42 χ 8.57 χ 10 "" ⁷ 1.30 / 2.27 33; 3.84 60 53 75 / 9.8 750 Year Malonic acid 1.49 χ 2.03 χ 10 ""? 10 ~ ^b 2.75 / 3.94 2.86 2.58 30 KFT - - ro O -O VJl 03 cn Amber acid 6,89 x 2,47 x 10 "" I 10 "" ^b 4.16 / 5.64 2.75 3.28 60. 54 81 / 10.5 , 783 Fumaric acid 9.30 χ 3.62 χ 10 ^. 2.8 / 4.24 30 KFT - - o-phthalic acid 1.3 x 3.9 χ 1O "" 3 10 ~ ^b 2.77 / 3.84 30 60 95 / 12.4 1100

Spruce Ghlorit-holocellulose

O? a b e 1 1 e III - continued

Organic · First Disso- First-time pH of the solution-cooking yield Kappa-DP Ziation Con- stitution pl, telgeraic it Pul Zhl /

constant in HOHO 60% before d

g acid

constant in H _p OH _p O, 60%

^d boil alcohol

before dam

Time

after the min. Cook

pp

on pulp number / TAPPI % residual lignin viscosity

Ferulic acid - - 3.77 4.4 30 'KFT 72 / 9.4 980 - a-p Nicotinic acid 1.50 χ 10 "^ _P 1.04 χ 10""'^ - 3.45 3.55 60 · 57 68 / 8.8 1000 Salicylic acid 1.07 x 10 ". 4.0 χ 10" ' 3.0 / 4.46 2.90 3.62 30 53 63 / 8.19 520 ι Trifluoroacetic acid 5.88 χ 10 " ¹ - 1.96   2.30 '15 52 - I Gallic acid 3.9 x 10 " ⁵ • - 3.72 4.1 30 ICB ¹ T - Monochloroacetic acid 1.40 χ 10 ~ 3 2.85 / 4.04 2.4 3.1 30 · KFT - Trichloroacetic acid .2 x 10 " ¹ 0.70 /? 1.98 3.65 30 KFT

All cooking liquids are ethanol / water mixtures 60:40.

All acids are 0.05 molar. KFT: no fiber separation

VjJ _i

VD

WHERE

ro

VJI

oo i cn

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According to the invention, fiber separation and saccharification of lignocellulose by acid-catalytic-aqueous / organic solvent mixtures is achieved.

Lignocellulose with the hot, watery ,. acidified organic solvent mixtures according to the invention are currently subject to the delignification and saccharification by the solvent mixture, so that progressively the components are separated from each other. Initially, the mixture only penetrates and hydrolyzes the readily accessible hemicellulose and lignin, and the dissolved hemicellulose sugar and lignin are passed into the bulk of the mixture; from where they can be removed by stripping off the liquid to avoid decomposition and to allow their recovery in a very pure state.

Shortly after insertion of the solubilization takes place _f when an aggressive acid catalyst is used, a random hydrolysis of the glucan, which starts at the accessible sites of the cellulose fibers, which are exposed by the removal of hemicellulose, proceeds to the microfibers and crystallites and at the appropriate time the cellulose is depolarized to a low DP. The strong acids - hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid - have the ability to lower the DP value so rapidly at molar concentrations below 0.05 as acid catalyzing compounds in the solvent mixture that at the time when cooking causes mechanical degradation Fiber separation, for example by refining or grinding the lignocellulose residue,

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- 46 -

made possible, the DP value has already been greatly reduced.

As cooking continues, the crystallites are further depolymerized by the hydrolyzing action of the solvent mixture until complete dissolution of the cellulosic network is achieved. To illustrate this, two batches of wood chips, one from oven-dry aspen, the other from Douglas fir, with initial DF values of 1160 and 1120, respectively, were stirred for three minutes in a 50:50 aqueous acetone solution having a molarity of HCL of O. _t 02, ie a concentration of 0.07 % 9 at 200 ⁰ O boiled. The initial pH was 2.8. The cellulose residue. had a DP of about 120 and contained only a very small amount of residual lignin. Such a DP value roughly corresponds to cellulose crystallite lengths in the starting cellulose of 60 nm (600 lbs.). Upon further boiling of the solute and residue, the EP value did not change significantly until all of the pesticides were hydrolyzed.

The effect of the other strong acids in such amounts that the pH of the solvent mixture was not more than 3 * 5 and preferably 2.5 or smaller, corresponds largely to the stated effect of HCl. When selective dissolution of hemicellulose and lignin is desired with little or no hydrolysis of the glucan, it is desirable to obtain pulps of superior DP value of high quality suitably a suitable water-soluble, volatile organic solvent such as methanol, ethanol, i.a. or n-propanol, butanol, acetone, methyl ethyl ketone, dioxane or pyridine, with a weak acid, such as Ma.lein- ₅

- 47 -

5. 4. 1979

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Oxalic, L-apple, succinic, o-phthalic, nicotinic or trifluoroacetic acid, used in a molar concentration between 0.025 and 0.05. Alternatively, one of the strong acids, buffered by blending a neutral salt of the acid so that the pk of the solvent mixture is adjusted to about 2.2 or below, can be introduced into the aqueous-organic solvent mixture to allow separation of cellulose fibers having high DP values. can be achieved.

The lignin dissolved from the solvent mixture can be recovered in an 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, MSO, methyl cellosolve and tetrahydrofuran.

The dissolved carbohydrates, which are in monomeric form, can easily be separated from the remaining liquid and further worked up, for example, by fermentation, dehydration, reduction, hydrogenation, etc. It has been found that the saccharification follows effect of the solvent mixture on the glucan first-order kinetics, ie, about 5 to 10% glucose yield per minute cook time at 200 gives ⁰ O.

-Execution example

The invention will be explained in more detail below with reference to some embodiments.

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'' - 48 In the healing drawing show:

1 is a schematic representation of the method according to the invention which shows which products are obtained when lignocellulose is treated for a different period of time,

2A, 2B, 2C are schematic representations of an apparatus for carrying out the method according to the invention for obtaining products according to FIG. 1 _t

In the following examples, which describe certain cooking processes, the influence of time and temperature on product recovery is examined. The selected preferred temperature and time parameters to which the various processes are adjusted according to the desired products follow general guidelines for the hydrolysis of lignocellulosic components. ie .:

approximate endpoint for a Hemicelluloseextraktion: 3 to 5 minutes boiling at 165 180 ⁰ O with a mild acid or a mixture of acid / salt;

Productsί lignin solution, low lignin pulp, hemicellulose sugar;

approximate endpoint for the production of a high quality pulp

Cooking time 5 minutes more at 200 ⁰ C with mild acid

or a mixture of acid / salt;

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

5i -4. 1979

C 13 K / 207 586

- 49 -

approximate endpoint for microcrystalline residue:

Cooking time 5 minutes longer at 200 ⁰ C with strong acid;

Products: high lignin pulp and low DP pulp, lignin solution, reduced sugars;

approximate point for complete saccharification:

Cooking time 4 to 10 minutes longer at 200 ⁰ C with strong acid;

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

Reference may be made to Figure 1, which illustrates the progressive decomposition of lignocellulose and the modes of recovery of products of particular process variants.

Example I

In this example and the accompanying Table IV the dissolving power for the constituents of cellulose of acidified aqueous-organic solvents is compared. In particular, ethanol / water / acid mixtures and acetone / Y / acid / acid mixtures are compared with respect to their effects per 100 g of Espe or Douglas fir schnitzel. Each 100 g of these chips were introduced together with 1200 ml of cooking liquid from water and organic solvent 50:50 in a test pulp boiler, wherein two approaches were impregnated with acetone-containing mixture and the other two with ethanol-containing mixture. All liquids contained 0.07 wt.% HI as

- 50 -

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- 50 .-

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 aqueous solvent 50:50 to adjust the desired acid concentration. Samples were taken from the contents of the digester at the indicated times without lowering the pressure in the container and these samples were analyzed.

table

temperature Time solution aspen Species Douglas Fir Residual lignin % ⁰ C minute medium Yield of pulp % Yield of pulp % 7 47.9 Residual lignin% 47.5 5.85 2.1 7 45.4 31.2 2.4 42.0 31.5 200 10 20 ethanol 28.6 1.8 0.5 26.8 2.13 30 43.5 34.1 1.30 7 34.2 1.0 22.5 0.75 10 15.1 0.35 12.3 - 200 15 acetone 10.4 - 6.5 , - 20 3.7 - 2.03 30

The values in the table indicate the superior dissolving power of the mixture of water, acetone and H 2 O since the

- 51 -

5; 4ί 1979 "AP G 13 K / 207 586

complete disharmony of Douglas fir, a hard-to-process wood species, required only 20 minutes. When ethanol is used as the organic solvent in the cooking liquor, yields of pulp of not less than 24 % are obtained even when the cooking time is extended to 60 minutes. The cooking times indicated in the Table include an initial interval of 5 minutes, during which the impregnation inserting and limited hydrolysis, while the cooker was heated with the Beschikkung in a room kept at 200 ⁰ C glycerin bath at process temperature.

Beispi elJEI

The influence of the acid concentration and the attack of the acid was on aspen wood within a limited range of ratios V / ater compared at a constant temperature of 200 ⁰ C to solvent "All HOL cooking operations were performed with a Lösungsmittelgemisch- of water and acetone, using a weight ratio Wood, liquid carried out 1:10 % All oxalic acid cooking operations were carried out with 0.5N acid and a solvent mixture of water and ethanol with a ratio of wood to liquid of 1s10. The acid / salt mixture HC1 / KCl was 0.0692m KCl and 0.0108m H 2 O in a 60: 4-0 by volume mixture of ethanol and water, and the ratio of wood to liquid was 1: 8. The stated pulp yields are to be understood as weight% of the feed. Sugar quantities and lignin are to be understood as percent of the yield ultimately achieved by the hydrolysis process used. The whole wood contains

- 52 -

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a total of 19 % separable lignin, a total of 74 % separable holocellulose, 56.3 % glucose-recoverable cellulose, and 17.9 % separable hemicellulose, which consisted of 1.9 % mannose and 16.0 % xylose. The values given show that an increase in the acid concentration of 0.01 m to 0.02 m __ when using HCl is little or no effect on the reaction rate constant at constant reaction temperature and slightly different ratios of organic solvent: water has. When the concentration was tripled - from 0.02 m to 0.06 m, however, a considerable effect resulted and the effect of an increase in the acid concentration at the higher concentrations is comparable to that of an increase in the temperature to the hydrolysis rate. »

table

Time min. Ratio of water: organ.solvent Starting wood aspen: 0.02 60.2 Lignin Glucose 'Mannose Xylose 19% 56.3 % 1.97% 16.0 % glucose mannose xylose Hydrolysis sensitivity O Ui Temp. 2 50:50 Acid & Yield Concentrate pulp m 0.01 67.1 to lignin % in solution, % 1,2. 1.3 14.9 0.11 Z 2 50:50 HCl, 0.01 65.1 15.9 0.9 1.2 14.3 IMM 2 40:60 HCl, 0.02 60.2 10.5 1.2 1.3 11.1 - 200 Second 40:60 HCl, 0.06 59.6 11.5 1.4 1.3 14.4 0.11 • 2 40:60 HCl, , 0.05 59.4 14.1 1.1 1.4 11.4 0.19 I 7 50:50 ^{ HCl, -0.05 .59,4 16.4 0.7 1.2 2.5 * - I 7 50:50 3> O3tt ^s 0,025 58.1 17.7 1.6 1.6 10.1 * MWM * 200 , 7. .,., 50:59 OXA, 17.7 - - -_ OXA, 14.2

50:50

HCL / KC1

65.6 ·

12.8

35 sugar levels before secondary hydrolysis; '·'. -

25 sugar values after the secondary hydrolysis for 60 minutes with 3%: r HgSO ^ at 120 C. fÖ - oxalic acid

VJL

ο 4 = ·

VaJ _i, VD

ro

VJL

00 iσ ».

5. 4. 1979

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The superior yield of pulp obtained with a buffered mixture of strong acid and salt and the high level of dissolved lignin maGhen make it possible to obtain a high strength fiber from plant materials of all kinds as shown next.

The tenacity of the cellulose pulp is greatly affected by the residual viscosity, i. the degree of polymerization of the cellulose after the isolation of the fiber influenced. Strong acids are, at low concentration, not specific in their hydrolysis effect insofar as they hydrolyze, i.e., hydrolyze, all glycosidic linkages in the lignocellulose, including those linkages found in the high-order regions. amorphous, mesomorphic and crystalline cellulose hydrolyze ·

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

A much higher DP value of the cellulose fiber can be achieved using shortened delignification times

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when an oxalic acid catalyzed aqueous-organic solvent mixture is used, Bs were found to be KP values of the released fiber close to those of virtually undegraded natural fiber.

Beispiellll I II Ι- «« II ..i .a \

A number of 5 g crushed, oven dried aspen and spruce wood jars were cooked in a high pressure stainless steel kettle with 60 ml each of a mixture of water and ethanol 40:60. To each feed was added specific amounts of HIO, oxalic acid or buffered HC1 / KCl. The acid / salt mixture contained 0 _$ 0692m KCl and 0.0108m HCl in the 60:40 ethanol / water mixture by volume to give the impregnation mixture. had a pH of 2.2. Yields and DP values of the remaining cellulose are summarized in Table VI. The degree of polymerization was determined by the method of using an iron / tartaric acid / sodium complex. The ratio of wood pulp used in aspen wood was 1:12. and when using spruce wood 1: 8, except for sprinkling with spruce with HCl using a 1:10 wood to liquid ratio.

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Temp C

T a b e 1 1 e VI Time Acid and min Concentration molar aspen

wood species

Fichte

From left to right prey lignin DP prey ligan to nin

Pulp %

Pulp %

Starting wood ί 5 HOl, 0.02 77.36 ¹ 0.67 1140 77,50 1.3 1220 - 5 0ΧΑ.3ί, 0, Ο5 46.9 1.0 120 47.8. 5.24 187 440 10 OXA., 0.05 53.2 4.9 980 50.9 6.42 640 200 ² ^ OXA., 0.05 51.2 3.5 700 Ina Ma - 5 OXA., 0.025 - - - 49.2 4.5 630 10 OXA., 0.025 59.4 5.8 1125 - ". 200. 15 OXA, 0.025 52.9 4.0 1025 67 15.6 987 3 HOl / KCl 51.9 2.31 870 65 14.3 ' 675 7 HOlAOl 65.6 6.2 465 -. - 200 56.8.  4.8 450 50.9 6.09

OXA = oxalic acid

= Values for chlorite-holocellulose

These values show the extraordinary improvement in the strength of plant fibers of all kinds over those previously obtained by chemical or bacterial / fungus action. The strength of paper webs, laminates, filters, yarns, ropes and ropes from all fibrous plants can obviously be demonstrated by the application of the method according to the invention for release

- 57 -

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- 57 -.

Such fibers are very much improved.

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

Such improved pulp is obtained in lower yield, but with higher sheet strength and in much less time than is required to make pulp by chemical action alone. The process of the present invention can be easily used for the production of very high webs Strength can be carried out at low cost and in a short time, the cooking either in individual batches or continuously or either in one stage or in two stages using a solvent mixture 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, comminuted wood, straw, sugar cane or bagasse can usually take place at a pulp temperature of about 180 ^° C. in a time of only 3 to 5 minutes. To this

^: - 58 -

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 · - 58 -

Although the lignocellulose residue is softened, it still retains its initial structural form when the material is stirred in a liquid and yet can easily be made into a fiber dispersion, ie pulp, by one or more high-pressure grinders in which it high liquid shear forces results, so that a, thermo-mechanical pulp is formed. Lignin contents of 5 to 6 % can be achieved and a pulp of exceptionally high strength is obtained.

The cooking liquor or cooking liquors may be further processed in the manner described below to recover organic solvent and other dissolved materials.

For instance, pulp pulping for the production of regenerated cellulose requires a bleached pulp DP value above 800 and a minimum c &quot; cellulose " content of 85 % or higher described.

example TV

A number of sets of air-dried flakes of aspen, spruce and birch wood of 20 g each with flake dimensions of approximately 2 cm χ 6 cm χ 0,8 mm - 1,5 mm »Sugar cane fibers of 3 mm χ 3 mm χ 10 cm and wheat straw of 10 cm length, also 20 g, was performed. Each feed was mixed with solvent mixture such that the weight ratio of feed to solvent

- 59 -

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- 59 -

1:10 mixture was placed in a stainless steel bomb cooker. The solvent mixture consisted of 60 parts of ethanol and 40 parts of water and contained so much oxalic acid that its concentration was 0.05m. The temperature of the digester was brought to 200 ⁰ G in about 7 minutes, and the cooking was carried out at this temperature for a certain time. The resulting pulps were analyzed for yield, residual lignin, DP and ε l cellulose. The values obtained are summarized in Table VII.

T a bell " 5 VII 85.4 DP TAPPI Viscosity · species Cooking time min. Yield of pulp % 85.8 970 aspen 1.5 51 Remainder <*. ~ Cellu-. lignin-free%% 86.0 950 Fichte 20 57 9.1 · 88.0 1100 birch 15 54 95k 89.0 1300 Sugarcane bark 15 53 25 3? 1280 Woizenstroh 15 54 33s 37s

s - kappa number

The above values show that all pulps obtained in this way had a qC-cellulose content of over 85 % . All of these pulps responded extremely well to a three-stage bleaching sequence of chlorination, extraction-hypochlorite, after which the whiteness was quite comparable to that of bleached pulp, ie 88%. The

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- 60 ~

oC-cellulose levels ranged from 95 to 99%. Example V

The removal of the major part of lignocellulose lignin, such as straw, grasses, sugar cane residues and various hardwoods and softwoods, has also been used to improve the digestibility of such material by ruminants. However, the cost of the delignification was so high that such a material could not compete with the conventional cattle feed. In addition, in some known methods of delignification, the residual lignin is altered so that the lignocellulosic residue is toxic to children _e

By the present invention, the cost of Entlignifizierung be largely reduced, and obtained in a short cooking time Eestlignin content below 5%. A number of experiments were carried out with 100 g each of air-dried aspen, Douglas fir, spruce, bagasse and wheat straw. Each feed, together with a 60:40 acetone / water mixed solvent, which was 0.02 M hydrochloric acid, was placed in a stainless steel pulp digester. The cooking temperature was 195 ⁰ Ci after a heating time of 6 to 7 minutes and different cooking times were used. Yields, Eatligningehalte and digestibilities are summarized in Table VIII.

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- 61 -

Table VIII

species Cooking time min · Yield% Residual lignin % Digestibility of the dry material, % aspen 7 40 0.39 91.3 8th 36 0.14 92.5 Douglas 7 40 3.43 75.4 fir 8th 30 2.73 84.8 Fichte 7 45 5.00 74.0 8th 37 3.6. 74.4 bagasse 5 64 5.7 56.4 7 50 3.5 67.1 as straw 7 64 3.6 78.6 15 2.8 89.1

The stated digestibility was determined in vitro by the method of R.W. Mellengerger et al., 1970 »J. Anim. Be. 3 1005-1011, determined. 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 by the process according to the invention to produce an excellent cattle feed from heretofore poorly or not at all suitable vegetable material. By recovering by-products from the cooking liquid such as lignin, sugars and recycled solvent

- 62 -

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- 62 -

reduced the cost of carrying out the process and the required equipment. The apparatus used may be a one-pass kettle using an open trough at room temperature for impregnation with the solvent mixture. The plant consists of a pressurized wood particle feeder, a gate capable of withstanding a pressure of 35 bar, a heating system, a high pressure heating and injection system for liquid, return lines, a bottom cooling and washing device, a purging centrifuge , a simple flash evaporator for solvent recovery, a feed mixer and a pelletizer for the pulp.

Example VI

Some organic acids, which promote fiber separation in admixture with aqueous-organic solvent mixtures, have particular advantages when it is the aim of the hydrolysis to dissolve hemicellulose and lignin, but to obtain a high DP of the fiber by gradually decomposing at the cooking temperature, whereby their effect on the glucan is limited. For example, at the higher cooking temperatures, oxalic acid decomposes to CO ₂ and HpO and salicylic acid to phenol and COp, so that the initial rapid hydrolysis with the 0.05M catalyst at the start of cooking allows early release of the fiber through the solvent mixture so catalyzed the hydrolysis effect when the cellulose is exposed becomes milder.

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- 63 -

A test series without lignocellulose with oxalic acid as catalyst in an ethanol / Vaser mixture 60:40 and an acid concentration of 0.05 m was carried out by boiling at 200 ° C. The pH was from time to time over a. Period of 30 minutes, and samples were taken to titrate the liquid and to measure the residual acid. Another series of experiments was conducted using one liquid containing no organic solvent and, in another series of experiments, equal parts Acetone and water used. The values summarized in Table IX show a progressive and rapid decrease in the acidity of the solvent mixture over time, with this reduction being greatest for ethanol / water and lowest for water alone. , -. ·.

Table IX

cook H ₂ O + OXAkk Solvent mixtures 0 + OXA.35K Acetone / HgO + OXAkh time min * pH Oj05 balance NaOHs OXAccml% Ethanol / Hp Remainder Ö2A3EK % pH 0.05 NaOH ml Rest OXA.BK pH 0 ₉ 05 s · NaOH ml

O 1.71 50.5 100. 2.02 51.15 100. 1.90 51.3 100,

7 2.10 32.9 65.2 2.45 19.0 36.9 2.30 25.3 49.4

10 2.20 25.8 57.0 2.91 11.0 24.4 2.91 19.4 37.8

36.5 3.26 10.4 20.5 2.95 18 ₉ O 35.1

33.4 3.37 9.0 17.5 3.10 16.8 32.7

33.9 3.41 8.7 16.9 3.11 16.2 31.6

33.8 3.45 8.0 15.5 3.13 15.4 32.0

15 2.88 18 2 20 3:05 16 , 9 25 3:04 17 , 0 30 3.04 17 ,1

s consumed by 25 ml sample sss = oxalic acid

Cooking fluid - 64 -

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- ⁶ ^ -

The practical applicability of this phenomenon was flakes by a series of experiments in which aspen, spruce and birch wood · at 200 ⁰ C in a solvent mixture of ethanol / water 60:40, acidified by adding oxalic acid was cooked to an acid concentration of 0.05 M, educated. Table X summarizes yields of pulp, residual lignin and HP of the fiber.

Cooking time min · T abe 1 1 e X EP TAPPI Viscosity Initial concentration of oxalic acid species 8th Yield of pulp Residual lignin kappa number / % 1250 0, .025m 10 62.3 58 / 7.54. 1200 0.025M. aspen 15 59.63 52 / 6.85 1180 0.025M 10 51 39 / 5.19 987 0.05m 15 67 120 / 15.6 - 0.05m 20 65 110 / 14.3 950 0.05m Spruce 30 57.3 95 / 12.3 - 0.05m 10 56 97 / 12.6 1360 0.05m 15 63.2 35 / 4.55 1320 0.05m birch 20 60.8 25 / 3.25 1170 0.05m 57 27 / 3.51

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~ 65 -

The rate of loss of woody substance is about 2.5 % for every 5 minutes cooking time extension after an initial heat up time of about 7 minutes The fiber is released in aspen, in a cooking time of 7 to 5 minutes and in spruce in a cooking time of 8 blank, 5 to 9 minutes · the low cooking losses seen that the decomposition of the acid promotes the retention of high DP-values of the fiber.. _r

If the digester is a container, are arranged at the inlet and outlet ports at a large distance from each other at opposite ends of the B _e hälters and which is provided with means for movement of the lignocellulose and Lösungsaiittelgemisches, the relative movement between the flowing liquid and progressive lignocellulose so can be chosen that the yield and recovery of the products and the fiber quality are optimal. The decision as to whether liquid and solids are run in parallel or in countercurrent depends on which target is to be achieved by cooking. In general, the entlignification effect of cooking is greatest when the highest acid concentration is present at the beginning of cooking. However, if it is desired to obtain temperature-sensitive hemicellulose sugars 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 preferable. If the solvent mixture temperature-sensitive organic catalysts such as oxalic acid and

- 66 -

-2-07.586

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AP C 13 K / 207 586 c

- 66 -

Salicylic acid, "the countercurrent flow must be used to avoid premature deterioration of the hydrolyzability of the solvent mixture, using a plant as shown in Figures 2A, B and C, to recover the entire range of products made from lignocellulose can be obtained, as illustrated by Fig. 1, η operations can be considered.

According to FIGS. 2A, 2B and 20, lignocellulosic chips are continuously thrown from the conveyor belt 1 as feed to a screw 2 and are fed through them at a specific speed to a high-pressure screw 3 of a pre-impregnation device 5. The chips that arrive at the end of the screw 3 are preheated with a solvent mixture which is pumped by the pressure pump P and supplied through inlet 4 at the inlet end of this device to a temperature above 100 ⁰ C and preferably from 150 ⁰ C to the impregnation initiate.

The sliced chips are introduced via the high-pressure screw conveyor 6 into the first container 9 of a two-stage cooker 100. In the container 9, the slices are mixed with a first, preheated cooking liquid supplied through line 7 and storage tank 8 and the heating device 7A This liquid is formulated to dissolve lignin and to partially hydrolyze hemicellulose, and may consist of 70 to 30 parts acetone and 30 to 70 parts water, preferably about 50 parts solvent and 50 parts water the liquid consists of ethanol and water in the same ratio

- 67 -

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APC 13 K / 207 586

- 67 -

and containing such an amount of acid catalyzing acid bond which may be oxalic acid present in the solvent mixture at a concentration of from 0.025m to 0.05m and the mixture has a pH in the range of from 3 * 5 to about 1.7 ». preferably about 2.2. The ratio of wood: -is liquid in the impregnation zone of between 1: 4 and 1: 151 preferably about 1:10 held · The temperature of air entering the container 9 liquid is 180 ⁰ C or above, the temperature of the sojdaß flakes or shavings increased rapidly and the dissolution of lignin and hemicellulose is initiated.

The liquid is kept in motion, either by circulating it between the inlet site and the filter ring 10, or by countercurrent flow. When the flow directions are parallel, the solvent mixture exits through the filter ring 10 and flows through line and heater 12 Inlet of the container, unless it is withdrawn after a certain impregnation time on the filter ring 10 and the conduit 13 and the expansion chamber 14 is fed, followed by an EntEpannungsverdampfung of the volatile materials, after which they are passed through the condenser 15, where some of the vapors of the organic material by L _TION 16 is blown off to be then collected in the Kondensorleitung 67th

The bulk of the recovered first solvent mixture containing extracted lignin and extracted sugars and therefore referred to as "spent" is collected in line 17 and fed to the tank 18. At a prevailing in the first pressure vessel 9 pressure

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- 68 -

from 19 to 22 bar (280 to 320 psi), the residence time of the flakes or chips may be about 5 minutes and depends on the temperature, which may be in the range of up to 185 ^° C or above. In Table XI are analyzes of a lignocellulosic residue passing through the pitting ring 10 and of 100 g of oven dried wood with a first mixed solvent of acetone / water 50:50, with HCl in a concentration of 0.02m or a concentration of 0.07 % acidified, obtained, indicated,

Table XI

Temp · cooking wood species

Oq time '' ·

minute Aspen Douglas fir

Remainder residual lignin xylose residue residual ligand

Pestlig- in Lö- in Lö- Festigin- nin nose

solution of stof-nin in Lö-in

ff> _ _ _ _ f (Λ '

0 / of of 0 / "Cy0 ~

180 5 69 2.3 74-H 93h 67 5t7 46s

The values mean extracted component in % of the potentially extracted from the oven-dry wood

Amount:

Aspen lignin 19%, aspen xylose 16%, Douglas fir lignin 31.5%, Douglas fir mannose 10.8%.

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- 69-

The parisels, which are partially cooked in the container 9, are guided through the filter ring 10 and enter the second container under the effect of a conical feed throat 20. The degree of rejuvenation of the feed screw 20 must be adjusted to the rate of dissolution of the pesticides, the volume of which continuously decreases as they move through this container 19. The second mixed solvent is supplied via line 21 and preheater 22 from the tank 23 and enters a temperature of 210 ⁰ C in the container 19 a. The residence time of the chips progressing in this container 19 is determined by the speed at which the feed chute. 20 is controlled, and this control is the main means by which the process is adapted to the desired product, associated with the rate at which the solid residue is passed through the second filter ring. In this section the liquid circulation is essential and the movement of the second solvent mixture is parallel to that of the solids at a rate which is somewhat or substantially greater than that of the solids.

The second solvent mixture is withdrawn from the container 19 after a certain contact time through the filter ring 24, the conduit 25 and the heater 26, so that the cooking temperature can be maintained accurately. The pressure developing in vessel 19 using a solventgenic acetone / wssser 50:50 containing 0.07 % HCl and having a pH of 2.2 is about 24 bar (480 psi). If the liquid is enriched in dissolved material or has reached its maximum residence time, it will be passed through line 27 and the

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deduction chamber 28, which is connected to a second condenser 29, deducted. The condensate is passed directly into the tank 31, while the steam via line 30 in the condenser 67 led out vard. Under normal conditions are in the second container 19 at the conditions described for the separation of the fiber from the. Lignocellulosic residue is required for 2 minutes. Yields and recovered products for the use of aspen and Douglas fir are summarized in Table XII.

Table XII

Temp · cooking wood species _____

° ^C JJi * Aspen Douglas fir

Pest residual lignin red. Solid residual lig. ·· red

substance-lig- in Lö- sugar- substance- lig-

excl. ninin in ker

Loot Loot Solv. ges.

200 2 + 5 50.5 1Λ 5.0h 10.5 »47.5 3.5 46.0 11.0 - 1

ges.

κ Biese Yferte indicates the percentage of extracted component based on the potentially extractable amount (see Table XI).

When the formation of dehydration products in the withdrawn liquid, which takes place when the dissolved sugar for a long time a high temperature and a low pH

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be avoided, the liquid, for example, with lime water, quickly neutralized and stored in a tank until it is processed further. For further processing, organic solvents are evaporated and the precipitated lignins are separated by filtration / centrifugation. The aqueous solution may then be stored either with a preservative or. for example, to a concentration of from 20 to about 50 %% to a syrup.

In order to maintain cooking temperatures, it may sometimes be necessary to add heat from the outside to compensate for the heat, heat losses in the device, etc. consumed in the endothermic reactions. Therefore, both tanks of the cooker must be equipped individually with heating and rising rvorrichtungen. 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 intended to hydrolyze glucan.

If the main product is to be pulp, the solids entering the prewashing zone 32 through the filter ring 24 are immediately sprayed with a cold, acid-free liquid 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 level at which any further hydrolysis ceases and a re-precipitation of the lignin from the remaining spent liquid is avoided. The consistency of the pulp desired in this section is 20 %,

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-7a

The liquid recirculation is continued through line 33 and line before the pulp is fed through high pressure feed screw 36 and intermediate pressure feed screw 37 into high pressure device 38 where defibration is terminated before the pulp passes through line 39 into the evaporation tank 40, where it is fully cooled and released from a reduced pressure of about 3.4 to 10.3 bar (about 50 to 150 psi). Relaxation and bleeding of a portion of the volatile components and products in the "spent" liquid may occur via line 41 connected to the condenser line 67. The somewhat cooled, expanded pulp is fed by means of the screw conveyor 42 into a spin dewatering device 43 where it is continuously washed with further small amounts of cold water from line 44 to remove residual water soluble products. The effluent from this dewatering device is fed in part through line 45 to line 33 and partly through line 53 to the liquid recovery / storage system.

The dewatered pulp is fed through the screw 47 to the screens 48 while being re-slurried with water from the line. The remaining on the screen coarse material is washed in a collector 51 and pumped from there through line 52 to the impregnation zone 2. The finished material is washed in the first Preßwäscher 50, where it is further washed with water. The wash water, which is low in dissolved material, is passed through lines 53; 46 and 45, and partly on a continuation of the 53

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 -73-

Conservation of spent cooking liquor to separate sugar from it. The. Sugar-free pulp is scraped off the wire mesh of the scrubber 50 by means of a scraper 54 and fed via a conveyor 55 to the second scrubber 56, where it is washed with solvent to remove adsorbed or re-precipitated lignin a high concentration of volatile organic material to compensate for the residual water coming from the previous scrubber 50 and is preferably a good lignin solvent mixture such as acetone / water 80:20 or even pure acetone. Since the lignin content is low at this stage, usually between 1 and 3 % , this liquid is advantageously used in the zone 32 as the first washing liquid and supplied to this zone through the lines 58, 46 and 45. The slaked, solvent-wetted pulp is squeezed through squeeze rolls

59 to further reduce the Lösungsmitteigehalt before it is fed via a dryer 61 of the packing station 63. Collected drain is through pipe

60 also returned to the washing zone 32. The vapors from the dryer are fed through line 62 to a condenser to be recovered.

The dried pulp can either be packaged as Kollerstoff into bales or be formed into sheets. The further processing of the pulp can be done 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. When it is made into a web, the drying may be stopped after the washing liquid has been removed and the pulp may then be rebuilt.

5. 4. 1979

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be sludged, after which they can be processed in a machine to sheets of conventional dimensions. Alternatively, pulp to be used as feed may be dried to a moisture content of about 10 % , blended 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 a better appearance and a better taste to odorless vjeißen pulp. The feed may then be pelleted and packaged with a suitable moisture content in the range of 15 to 20% as feed for ruminants.

The recovery of the organic solvent or solvents used in the solvent mixtures and dissolved products from the extracted cooking liquors is an essential part of the process according to the invention, as it can substantially increase the economics of the process. The spent liquids collected in tanks 13 and 31 must be worked up separately because they contain dissolved solids of ultimately different utility. The stripped cooking liquid collected in the tank 31 is fed through line 64 to a flash steamer 65 or to a battery (not shown) of such devices where residual organic volatile materials are withdrawn as steam via line 66 by controlled distillation, operating to produce a char another breakdown of dissolved sugars, such as caramelization, is avoided. The remaining aqueous solution containing the dissolved sugars, part of the water-soluble

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- 75 -

containing lignin and any sugar degradation products, such as humic substances, is fed through line 76 to a settling tank 77 to separate the small amount of precipitated lignin by settling.

The clear sugar solution containing the bulk of glucose hydrolyzed from the lignocellulosic residue is then fed to tank 79 via line 78. The sediment from tank 77 is fed via line 80 to the spin-drying centrifuge scrubber 85 to recover lignin at 86 ° while the sugar solution is returned to a glucose tank 79.

The thus separated lignin obtained by working up the contents of the tank 18 as described below is in powdery form and has excellent solubility in the usual · lignin solvents such as ethanol, acetone, DMSO, furfural and tetrahydrofuran. From acetone solutions, the lignins can be easily purified by precipitating them in whole or in fractions by incorporation in excess of water or in another poor lignin solvent, it being essential that the lignin solution be prepared by incorporation of powdered lignin in a minimum of acetone In the precipitation of lignin from aqueous-ethanolic solutions Schx tigkeiten occur because the lignin gum-like sticking when the critical temperature range - 60 to 70 ⁰ C - is not respected · This problem can also occur especially in the solvent removal, so that the residual solution contains large lumps of semi-molten lignin and

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C 13 K / 207 586

- 76-

only partially by precipitation can be clarified. The addition of acetone to such a solution as to bring the precipitated lignin into solution again so that a clear solution is obtained, allows a clear precipitation of the lignin by flash evaporation of the acetone and the separation of the powdered lignin. Hardwoods, such as aspen wood, usually give a finer precipitate, and the ligninous precipitates are easier to separate by centrifuging than by filtration.

The prehydrolysates collected in the tank 18 contain the bulk of the dissolved lignin and the valuable hemicellulose sugars and are supplied via line 81 to a flash steamer 82 or to a battery (not shown) of such evaporators. The vapors released therein are passed through the condenser line 83, while the aqueous solution carrying the precipitated lignin and hemicellulose sugar is fed through line 84 to the spin-drying sentrifugal scrubber 85, where the sugar solution is collected from the lignin collected at 86 is, is separated. The clear hemicellulose sugar solution from the lower part of the centrifuge 85 is supplied to the tank 87. The collected condensate flows in line 67 through a preheater 68 to set the desired steam temperature before entering the fraction 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 the highest-boiling fractions (furfurals, levulinic acid, including acetic acid, which is formed by conversion of acetylene), then the fractions with medium boiling

4. 1979

C 13 K / 207 586

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 decomposition of methoxyls at high temperature.

The distillates from this column are through lines

92 of a number of tanks, such as 93, 94, 95 fed / methanol

is recovered from the top of the column along with the major portion of the acetone and its azeotrope with water containing 18 % water. Methanol does not appreciably affect the resolving power of other organic solvents used in the solvent mixture, but its amount should be kept below 5 to 10 % of the mixture.

D _a is separated s acetone by passing the azeotrope through a rectifying column 71, after which the anhydrous solvent is recycled via line 7 ² I- to the tank 75 of the azeotrope of acetone / water, or the aqueous solvent can be supplied to the tank 73rd The compositions of the various cooking liquors are adjusted by drawing solvent from tanks 75 and 73, from water line 89, and from acid tank 88, with mixing being regulated at 90, from where the mixture is fed through lines 91 to tanks 8 (first solvent mixture). , 23 (second solvent mixture) and 34 (washing liquid) is supplied.

An analysis of the recovered products at the end of second stage cooking is for aspen wood and Douglas fir

5έ 4o 1979

AP C 13 K / 207 586

compiled in Table XIII.

! table XIII

Wood Temp · Z _e it off residual solved. Eq. MGXA j?

^Q 0 min pre-lig-lignin or

at nin HMF

pulp

200 7 50.6 1.4 85 6 .8th 51 61 93 65 1.0 aspen 2ßO 8th 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 8th 41.8 2.7 95 40 18 5 1 1 6.2

D-T = Douglas fir Gl, = glucose M = mannose G = galactose • X = xylose A = arabinose F = fuffural

HMF = hydroxymethylfurfural

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

7 5 *

5 · 4, 1979

AP C 13 K / 207 586

The pulps after eight minutes of cooking contained 95 % glucan and had the following whiteness, as measured on the GE scale, with the first number referring to 7 minutes cooking time and the second to 8 minutes 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 7 minutes cooking time is attributable to the fact that hemicellulose and glucose were separated from the withdrawn first cooking liquor before further hydration could occur. · · · · · · ·

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

The properties of a number of high quality pulps, such as can be obtained at the end of the drier 61, were determined by further testing softwoods and hardwoods, namely spruce, pine (Southern pine) and Douglas fir, aspen and birch, and Agricultural residues, namely sugar cane bark and wheat straw, were digested in the digester. Each experiment included 2 Kochs.tufen, wherein the temperature of the first solvent mixture below 185 ⁰ O, and the time was 5 to 6 minutes and the final boiling at 200 ⁰ G for a sufficient time that the fiber only by the action of liquid on the residue in which liquid

207 586

: '5. 4. 1979 AP C 13 K / 207

-tfO-

could be separated. The acid catalyst was either 0.02 M HCl or 0.025 M or 0.05 M oxalic acid or 0.025 M Hl / KCl to adjust the pH to 2.2.

The pulps were analyzed according to TAPPI standard methods. The kappa number of lignin after T-236; the viscosity after T-23O; the whiteness according to T-217; the Canadian standard freeness after T-227; the standard strength determinations after grinding speed assessment in a PFI mill after BOIT B-6-1; and the production of standard T-205 handsheets. The strength tests were TAPPI Standard T-220, T-231, T-403, T-4-04 and T-414 ·. The handsheet weights ranged from 59 to 61 g / m · Some of the pulps of Table XIV were still undergoing a modified three-stage treatment, namely chlorination, alkali extraction, hypochlorite bleaching according to BCIT T-4-. 5. 6-1, which was developed for bleaching small amounts of pulp, subjected. The table gives some of the fourth pulps obtained by the Kraft process, it being noted that, although the chemical concentrations and consistencies proposed for the bleaching standard processes are complied with, in bleaching they comply with the process according to the process of US Pat Modifications of the invention obtained by the invention were made by the. Times of 60 to 30 minutes for the chlorination at 20 ⁰ G, from 90 to 10 minutes for Alkaliextralction at 75 ⁰ C and from 90 to 10 minutes for the hypochlorite, as for the production of kraft pulps with much lower kappa Numbers were applied, the fibers were lowered on a Buchner funnel

5 ·· ^. 1979

AP O 13 K / 207

The whiteness of the bleached pulp was measured according to TAPPI Standard T-218. The whiteness of the bleached pulp was measured to be uniform cake over a filter paper and dried between blotter paper until air-dry. Table XV shows the sometimes very slight changes in pulp properties due to the mild bleaching required to achieve a very high whiteness.

- & Γ-

T from the XIV-A

Lignocellu loose, acid, cooking time min. From booty Coarse particles Yield · sieved Kappa number Residual lignin White degree TAPPI Viscosity cp EP White degree to bleaching CSP \ ISA ASP Krapt 54.0 - _ 4.0 _ _ _ S I ASP OXA-10 59.63 0.98 58.88 39.9 5.19 72 41.3 1780 88 671 I ASP OXA-15 54.99 0.75 54.01 10.0 1.35 63 21.3 1280 88 705 ASP HOl-8 46,75 1.09 45.66 20.2 2.63 42 2.94 380 84 453 ASP-B-10 57,80 0.19 57.61 19.1 2.48 51 6.67 700 - 542 SPR Krapt 50.0 - - - 5.0 35 - - to * - SPR OXA-20 57.30 0.22 57.08 79.5 10.34 45 10.28 950 84 730 Ω SPR-HCl 10 50.95 0.22 , 50.73 46.4 6.03 38 2.07 300 - 145 VJJ "ro O SPR-HB-10 50.96 0.19 50.77 48.4 6.09 45 3.71 440 85 617 Vn 03 MG-KRAJO? 54.0 - - - 3.0 - - - - SOAN-OXA-9 55.05 0.42 54.54 16.0. 2.08 51 22.47 1380 80 485 BAG-HCl 6 43.37 0.26 43.11 50.0 6.50 39 2.91 380 - 229 *

Ausbuh-Grob- te teil- % chen _ T a b e lie XIY-A - F o r t s € i t TO White - CSF grade after bleaching. .% -_ - O 4 * Lignocellu loose, acid cooking time min. 58.0 0.84 Sucked from prey Kappa number Residual 'nin White degree TAPPI viscosity cp DP 430 670 IHE KRAFT 56,20 1.13 8.8 ._ 83 185 743 WHS-OXA-10 43.73 0.40 55.36 50.0 6.50 54 22.11 1360 - 748 2,2) WHB-HCl. 8 59.65 1.50 42,60 23.4 3.42 61 3,2 ' 400 81 768 SOP OXA-10 60.25 MM 59,25 53.6 7.62 41 5.78 " 600 82 SOP -HB -10 54.0 0.77 58.75 78.7 10.23 41 9.64 850 -. BIR KRAFT 60.88 1.60 - - 4.0 - - - 86 BIR-OXA-15 58.75 60.11 25.0 3.25 43 21.99 1320 75 DF-OXA-15 57.15 80.9 · 10.51 35 8.71 810 Sugarcane bark; BAG BIR - Birch; DF = buffer: (KOl-HCl, pH ASP = aspen; SPR = spruce; BAGs = bagasse, Ό. Mark; SCAN = bagasse; WHE = .wheat straw; SOP = Pine (Southern Pine); Douglas fir; OXA = oxalic acid; HGl = hydrochloric acid; B, HB =

OXA, HB, B in ethanol / H ~ 0 60:40 and HCl in acetone / H ₂ O 60: 40 ^

VjO

ro 0

vD

VJl CO

207

% ft. · 1979

AP C 13 Κ / 207 586

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OJ OJ 4- IA

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207 5B6

Table XV

5. 4. 1979

AP C 13 K / 207 586

Wood species and bleaching condition

Yield residual white CFS 300

% Lignin grad Breaking TEAR BURST? %% Length _t m

Pitch: not

Bleached after

bleaching

Birch:

Not

Bleached after

bleaching

57.3 · 10.3 45 7700

4 to 9.6

57.2

84- 696Ό

82.0

67.7

60.88 3.25 4-3 10560 68.0

86 9460 57.6

47.0 38.4

65 to 64.8 ·

In the above description, the method by which the novel solvolysis methods for separating the fiber from the cellulose component of lignocellulose can be carried out is explained. It has been shown that certain volatile water-soluble organic liquids mixed with water are lignin solvents an acidic catalytic compound, preferably a mild acid, such as an organic acid, or a buffered strong acid, can be added to, by hydrolysis, hemicellulose and lignin within minutes of the impregnation of the lignocellulose with the hot solvent mixture containing such catalyst If at the beginning a solvent mixture, which a mild

207 536

5. 4. 1979

AP C 13 K / 207

Catalyst containing is used, a Faserfestjgkeit the released cellulose can be achieved by almost the natural DP value. By removing the solvent mixture and cooling and separating the volatile materials, the dissolved hemicellulose sugars can be obtained in high yield and high purity and pure lignin as a pale powder. From hardwoods a fiber with DP values of over 1000 and from softwoods a fiber with EP values over 800 can be obtained. When the lignocellulosic residue is further treated with hot solvent mixture using a strong acid catalyst, saccharification can be carried out until each stage of dissolution of the solids and sugars, and sugar dehydration products, organic acids, furfural and methanol can be obtained.

With the process according to the invention, a substantial cost saving over Kraft processes using 30 to 40 % chemicals per tonne of wood is possible because in the process according to the invention only 3 to 6% of acidic catalyst, based on the wood weight , be used. Continuous recovery of organic solvents and high quality lignin and sugars more than offset the cost of non-recoverable chemicals. In addition, organic acids are formed from the lignocellulose.

Claims (16)

10.1.1980 54, 146/18 invention claim A process for decomposing lignocellulose materials by boiling with an acidified mixture of 70 to 30 parts water and 30 to 70 parts organic solvent under pressure and at a temperature in the range of 160 to. 210 C, characterized in that the organic solvent is a water-soluble low molecular weight aliphatic alcohol and acid as an organic acid, namely oxalic, maleic, o-phthalic, L-malic, succinic, nicotinic, salicylic or trifluoroacetic acid or a strong acid buffered with one of its neutral buffering salts, namely hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, or as organic solvent a low molecular weight aliphatic ketone and acid one of the above strong acids used, the pH of the acidified mixture in the range from 1.7 to 3> 5, and after initial impregnation of the lignocellulosic material, maintaining the specified conditions for at least three minutes, boiling off the cooking liquor after boiling, washing the residue, distilling off organic solvent and volatile degradation products from the withdrawn cooking liquor and then condensing and evaporating remaining solution separates the non-volatile degradation products. Process according to item 1, characterized in that the organic solvent used is methanol, ethanol or acetone. 10.1 · 1980 54 146/18 Process according to item 2, characterized in that an acidified solvent mixture containing 60 to 40 parts of water and 40 to 60 parts of organic solvent is used. Process according to one of the preceding points, characterized in that the lignocellulosic material and the acidified solvent mixture are used in a weight ratio of 1: 4 to 1:12. A process according to any of claims 1 to 4, characterized by separating the volatile materials by steam distillation to precipitate lignin and fractionally condensing these volatile materials and thereby organic solvent and volatile thermal conversion products and volatile hydrolysis products, namely methanol, furfural, 5-hydroxymethylfurfural , Levulinic acid, formic acid and acetic acid, wins and separates from one another · A process according to items 1 to 4, characterized in that the precipitated lignin is filtered from the drawn off cooking liquid after distilling off the volatiles, it is then dissolved again in a lignin solvent to saturation, insoluble material is filtered off from the solution and the lignin solution is spray-dried or by mixing the solution with water pure finely divided lignin falls. A method according to item 6, characterized in that acetone, furfural, dimethylsulfoxide or tetra-lithium is dissolved to dissolve the lignin precipitated from the cooking liquor. 10.1.1980 54 146/18 used hydrofuran. 8. The method according to item 6, characterized in that one restricts the remaining aqueous sugar solution by steam stripping to a content of dissolved pesticides of 20 to 50 % and condenses the separated volatile materials fractionated. 9 »method according to one of the items 1 to 4, characterized in that one uses for the recovery of cellulose from • high degree of polymerization as the organic solvent methanol or ethanol and as the acid oxalic acid. 10. The method according to item 9, characterized in that one cooks the lignocellulosic material · with the acidified solvent mixture for a time of about five minutes at a temperature of about 180 ⁰ C, then the cooking liquid is withdrawn and the partially entlignifizierten residue with fresh solvent mixture at a temperature of not more than 210 ⁰ C and close to 200 ⁰ C boils until the cellulose fibers are separated by liquid movement, the cooking liquid is withdrawn and washed the cellulose residue with acetone and then with Y / asser. 11. The method according to item 1 to 4, characterized in that to obtain a cellulose of high degree of polymerization as the organic solvent ethanol "and as acid one with one of their neutral salts 207 586 10.1.1980 54 146/18 buffered strong acid used. 12. The method according to item 11, characterized in that boiling the lignocellulosic material with the cooking liquid for about five minutes at about 180 ⁰ C, then the cooking liquid is removed and the partially entlignifizierten residue as long with fresh Ijösungsmittelgemisch at a temperature of not more than 210 ⁰ C. and boils close to 200 ⁰ C, until the cellulose fibers by severing Plüssigkeitsbewegung • are bar, the cooking liquor is withdrawn, and the residue with acetone and then with Y / ater washes. Process according to items 1 to 4, characterized in that acetone is used as the organic solvent to obtain a cellulose of low degree of polymerisation, and hydrochloric acid is used as the acid. 14. Method according to item 13 »characterized by by boiling the lignocellulosic material about five minutes at about 180 ⁰ C, the first cooking liquid, and the partially delignified residue with fresh solvent mixture is withdrawn as long at a temperature in the range of from 180 ⁰ C to 200 ⁰ C boiling until a Teilverzuckerung of the cellulose takes place remove the cooking liquor and wash the residue with acetone and then with water. Method according to items 13 and 14, characterized in that, for the purpose of obtaining a microcrystalline cellulose, the second cooking stage is used for a while 20,7586 10 · 1.1980 54 146/18 Temperature of 200 to 210 ⁰ C carried out until the cellulose fiber is degraded by hydrolysis of amorphous polyglucose into the crystalline region » 16. The method according to item 1 to 4, characterized in that one uses acetone for an almost complete saccharification of the lignocellulose as the organic solvent and hydrochloric acid as the acid. Process according to item 16, characterized in that, in a first stage, by boiling the lignocellulosic material with a solvent mixture having a pH in the range of 3.5 to 2.2 at a temperature of about 180 ^° C for a Time of about five minutes releases the cellulose, stripping the cooking liquor, and in a second stage the residue with a solvent similar to that of the first cooking liquor but having a clean pH in the range of 2.2 to 1.7, so long for a Temperature of about 200 ⁰ C boils until the cellulose has gone virtually completely in! Solution. 18. The method according to item 16, characterized in that one cooks the lignocellulosic material with the solvent mixture having a pH in the range of 2.2 to 1.7 at a temperature of about 200 ⁰ C until it is completely dissolved. Process according to points 16 and 18, characterized in that the material is mixed with a solvent mixture to completely decompose the lignocellulosic material into lignin and carbohydrate degradation products 207 586 10.1.1980 54 146/18 boils at a temperature of about 200 ⁰ C and a pH in the range 3.5 to 1.7 until the lignin and carbohydrates have gone into solution and pentoses and hexoses are converted to their Purfurale. 20. The method according to item 9 or 11, characterized in that the material is boiled for about five minutes at a temperature of about 180 ⁰ C with the acidified solvent mixture, the cooking liquid is removed, the residue is washed with solvent and with hot water and then the residue fed to a high pressure defibrator. 21. The method according to item 10 or 12, characterized in that one introduces the acidified solvent mixture and the lignocellulosic material in a pressure vessel with inlet and outlet, the solvent mixture is circulated continuously through the lignocellulosic material and, if the process is carried out continuously, at a faster rate than feeding the lignocellulosic material to the outlet so that its residence time in contact with the chips is not more than five minutes, after which time the cooking liquid is withdrawn while fresh solvent mixture is introduced to replace the withdrawn mixture. 22. Method according to one of the items 14, 15 and 17, characterized in that the acidified solvent mixtures and the lignocellulosic material are introduced into a pressure vessel with inlet and outlet. - 33 - 10.1.1980 54 146/18 and allowing each solvent mixture to circulate continuously through the lignocellulosic material during the cooking times in question and, if the process is carried out continuously, the first solvent mixture in the same direction as the lignocellulose, but with greater. Speed as it delivers to the outlet and the zv / eite solvent mixture leads in countercurrent to the lignocellulosic residue. For this' / pages drawings