DD208173A5 - METHOD FOR OBTAINING WATER-SOLUBLE SACCHARIDES FROM CELLULOSIC MATERIAL - Google Patents

Abstract

1. A process for obtaining water-soluble saccharides from cellulose-containing material by treating the latter with gaseous hydrogen fluoride, optionally diluted with an inert gas at temperatures between about 20 and 120 degrees C, preferably between about 40 and 80 degrees C, which comprises subjecting cellolignin, a material composed largely of cellulose and lignin and being essentially free of pentosans and hexosans which has been obtained by pre-hydrolysis of natural cellulose-containing material with dilute mineral acid at an elevated temperature and under an elevated pressure, to treatment with hydrogen fluoride.

Description

Berlin, March 23, 1382 AP C 13 K / 234 420 59 894 18

Process for obtaining water-soluble saccharides from cellulosic! Material

Field of application of the invention

The invention relates to a process for obtaining water-soluble saccharides from cellulose-containing material.

The water-soluble saccharides prepared according to the invention can be further used, for example for the production of ethanol, for fermentation purposes, as cattle feed and others.

Cha characteristics of the known technical en solutions

Cellulosic materials are abundant and diverse in nature. A known such natural cellulosic material is z. B. the wood. It consists essentially of cellulose (a material mainly composed of glucose), hemicellulose (a substance mainly composed of pentoses and hexoses) and lignin (a polymeric substance with aromatic rings substituted by methoxy groups). The utilization of wood happens in many ways, for. B. for heat generation (burning), as a building material in the furniture and building materials sector etc »; even a purely former utilization of the wood is possible.

Chemical digestion processes, which cause not only the separation of the wood into its constituents, hemicellulose, cellulose and lignin, but also their degradation and transformation, have long been known «

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Methods usually provide aqueous solutions of mono-, di- and oligomeric saccharides, which may be subjected to posthydrolysis to glucose or directly subjected to fermentation to ethanol, concentration or evaporation to dryness. Possible applications of products thus obtained are z, B, in the field of cattle feed additives or preferably the fermentation raw materials.

Among the chemical processes for the saccharification of wood, two principles have been used industrially in the past: concentrated pulping

aqueous hydrochloric acid (Bergius-Rheinau-Udic) and the digestion with dilute sulfuric acid (Scholler-Tornesch-Madison); see, e.g. Ullmanns Encyclopadie der technischen Chemie, 3rd ed., Vol. 8 (1957), p. 591 ff. ..5

The digestion of cellulose-containing raw materials with anhydrous hydrofluoric acid has also already been investigated several times. Here, however, all previously known methods have not led to any technically satisfactory solution. The decomposition of wood with liquid or vapor pure HF at low temperatures is described in German PS 560 535. The recycling of the HF is carried out by evaporation or blowing off and subsequent condensation In continuation of this work, dorDE-PS 585 318 discloses an ancestor for the digestion of wood with gaseous hydrogen fluoride, which works in three stages on an absorption of HF on wood at 10 ° - 20 ⁰ C, digestion at 20 ° ~ 50 ° C and desorption at 100 ° - 150 ° C, wherein the HF A disadvantage here is the cooling effort for condensing the HF, as well as the fact that when Aufkonciensicren initially only a very uneven distribution of the hydrogen fluoride on the Reaktionsartkommandokommty a circumstance, the only by very long Verv / eilzeiton or strong increase of hydrogen fluoride ·· use can be counteracted, otherwise the yields s severely impaired.

In DE - S G06 009 an extraction with liquid HF is described, but which requires large amounts of HF and is subject to the Kach part, since? for evaporation of the hydrogen fluoride from the extract and the extraction residue (lignin) gro.Oe VIärivieiaon ^'r s 7.Vt-, and have again been removed in the subsequent condensation.

More detailed information on yields in this type of process can be found in Angew.ch'em. 46 (1933) 113/7 _f wherein in the absorption of the HF from the gas phase in a vessel with external cooling of 0 ⁰ C at a loading of 50 wt, ~ $ ^ HF bez. on wood 32% sugar on existing carbohydrates and at 100 wt .- ^ loading 86 % sugar bez. on carbohydrates is achieved, rather the return of the HF are there no further information.

All of these processes have the disadvantage of consuming large amounts of the expensive hydrofluoric acid, with the recovery of HI ¹ from the reaction products being very costly and in practice, high HF losses occurring.

A more extensive process is described in US Pat. No. 4,447,494, where the prior art is presented as follows: "If one works with highly concentrated or anhydrous hydrofluoric acid in liquid or gaseous state at low temperatures, the degradation of the wood is very limited uneven and therefore imperfect going on. First difficult at such a low Temperaturer, the distribution form of the hydrogen fluoride that is present as a fine mist in the air, a very _uneven} more so than the existing air uniformity. · de reaction 1st. on the other hand, It is known that in the saccharification of wood with concentrated hydrogen fluoride in both the liquid and the gaseous state, the wood particles react rapidly on the surface with the concentrated hydrogen fluoride, forming a hard, rather impermeable skin and shrinking, whereby further penetration of the gas into the gas Inside is inhibited U Moreover, the penetration of the wood particles is already made more difficult by the air present in the cells. It

Thus, an outer crust forms very quickly, which includes unsweetened material and prevents further saccharification. In order to eliminate these problems, it has also been proposed to carry out the digestion with concentrated liquid hydrofluoric acid according to an extraction method or to avoid crust formation by Zuraischung inert gases to the hydrofluoric acid, thereby achieving a more uniform and complete digestion. However, the extraction process works with a disproportionately large excess of hydrofluoric acid, and the reaction product retains large quantities of hydrofluoric acid without preventing crusting with all its disadvantages. The dilution with inert gases can diminish the crusting somewhat but never, and never cause the gas to penetrate evenly into the interior of the wood, since the wood is filled with air least parts of wood mass itself and by far the largest parts of air, which is located between and in the Holzzcllen. A practically anhydrous Wood example, consists of about 15 ° i Holzuiasse-iiirka 8!>% Air. Ba wood cells are extremely small in relation to the size of a still largely shredded wood, even with sawdust, the air content plays a 'superior'. Role.

Hardening of the surface of wood particles also appears to have been found in wood saccharification with aqueous mineral acids, such as aqueous hydrochloric or sulfuric acid, approximately in Z. Angev. Chem. 37 (1924) 221 the substances present in wood, such as lignin, mannan, galactan, etc., are referred to as "incrustations", which are also due to disturbing? Degradation products (furfurol, acetic acid, formic acid, etc.) were to be removed before the actual Holzverzuckerimg as possible. For the Kntfornung one would have - since the

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Hydrolyzability of these "incrusts" was known - even in the case of Holzverzuckerung by means of hydrogen fluoride to a kind of "prehydrolysis" with dilute mineral acid at elevated temperature and possibly elevated pressure can think. However, such prehydrolysis had not been considered; rather, in order to avoid the above-described disadvantages of Ho.ch and Bohunek, it was proposed to apply a vacuum of about 30 torr in the wood saccharification with hydrogen fluoride ^ AT-PS 147 494 + Supplement 151 241; the wood saccharification process with hydrogen fluoride according to Hoch and Bohunek is also described in the journal "Holz Roh ~ und Werkstoff" 1_, p. 342 to 344 (1937) 7 ·

Disadvantages of this method are the inevitably occurring during work in vacuum difficulties of technical implementation and the relatively complicated reaction regime. A deficiency inherent in all processes is the formation of mixtures of pentoses and hexoses by simultaneous hydrolysis of the hemicelluloses and the cellulose of the wood.

Another problem is the separation of the resulting from the hydrolysis of hemicellulose acetic acid, the difficulty as possible lossless "in-circuit guidance" of HF difficult, and the slight decomposition of pentoses to furfurol.

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23. 3. 1982 AP C 13 K / 234 59 894 18 - 5a -

The aim of -Erfind clothes

The aim of the invention is to provide an improved process for obtaining water-soluble saccharides from cellulosic! Material.

As a result of the essence of the invention

The invention has for its object to convert the cellulose into a form that can be easily digested with gaseous hydrofluoric acid, without forming crusts on the surface of the cellulose particles.

Surprisingly, it has now been found that the described disadvantages of the prior art can be avoided and a slight saccharification of cellulose is possible if the vegetable materials are not in their native form, but after a pretreatment in the form of "cellolignin" with anhydrous, gaseous HP unlocks.

β -

Under "Cellolignin" plant materials such as wood "straw, bagasse and similar raw materials are understood here that underwear a known Vorhydrolysc ο r f e η η ware" 5

This per se known prehydrolysis of the wood consists of a relatively short-term treatment with highly diluted mineral acid at higher temperatures and pressures, wherein essentially contained in the hemicellulose! ·] Pontosans and Kexonane up to the monomer units} such as z, B, xylose or mannose to be split. Depending on the reaction conditions, these can then be isolated as such or else undergo further changes, eg dehydration to furfurol or hydroxymethylfurfurol (compare Ulimann, loc cit, Vol. 7 (1957), p. Apart from fermentation, a further example of a technical use of hcrnicellulose degradation products is the reduction of xylose to xylitol. It is thus possible, even before the application of the open-end method according to the invention, to use Y.'ertert products made of wood by means of pre-hydr0 1 ys ο ζ ugcwi η η ο η.

V. ' eiterhi η ν; irc ³ hieru η t r C ο ο 3 e 11 i α η i η a υ P ch ar> ο i r material (eg paper), which arm of hemicellulose)!

5 is, vorstaudc-'ii. When is Vor'nydrolyr o of IIojz hlo.iJDt the P-trvilitwr woitceliond) get, but the so-recoverable Cellolignin has over the native Zust'and much mürbere and porous texture so that IiF, too - in a mixture with.! Air or other inert carrier gas ,.

it can be done easily without crusting the surface, working in a vacuum is not necessary »

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As a major advantage of the use of cellolignin instead of virgin wood, it is significant that the reaction material is much easier to handle in terms of process technology. " This is due, on the one hand, to the fact that, compared with wood of the same grain size, cellolignin has a bulk fraction which is only about half as large and thus has a significantly smaller degree of shrinkage upon digestion with hydrogen fluoride gas, which is EoB. for the dimensioning of reactors means a great relief. On the other hand, the reaction mixture of cellolignin remains free-flowing and free-flowing even in a state charged with hydrogen fluoride, whereas such from native wood is highly susceptible to sticking due to resinous impurities, as well as fission products of hemicelluloses and is difficult to require.

Naturally, such a tendency to sticking also impedes the desorption of hydrogen fluoride, especially if it is to proceed rapidly and as quantitatively as possible. However, this is readily possible when using collolignin as a substrate.

8th -

Furthermore, in this process, a separation of the sugar mixtures resulting from the hydrolysis of hemicellulose is no longer necessary from the oligomeric glucose components or "glucose" formed during the hydrolysis of cellulose, which makes possible an easier fermentative usability of these different sugars.

It is also advantageous that in the digestion of cellolignin no acetic acid and no more furfurol arise ^ so that you can lead the HF in a circle without having to condense these components. Thereby

Separation and RF losses are avoided.

Another advantage is the possibility of absorption of HF on cellolignin above the boiling point of HF, so that no external cooling is necessary. "It was also surprising that in the inventive method in simple V / eise yields of> 90 fi glucose or oligomeric Glucose be lied to a ™ set cellulose in cellolignin achieved, the resulting sugars are high quality, ie almost colorless.

Erfindungsge.gonstand is therefore a method for obtaining water-soluble saccharides (glucose or oligoinero glucose) to: ·; cellulose /! Material by treatment thereof with gaseous - optionally diluted with an inert gas - hydrogen fluoride at temperatures between about 20 and 12Ü ° C, ccrr.v /. between eiw.i 40 and 80 ⁰ C; the method being characterized 3Q gcykoriiizcichnet that :,] \\: \ n Ccllolignin a treatment with fluorine untewirft hydrogen.

Cellolignin is here, v.'ie previously defined, a largely consisting of cellulose and lignin material projected.

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In view of the state of the art, the recent more extensively developed method (Hoch and Bohunek, loc. Cit.) Seeks to remedy the disadvantages associated with uneven pulping and crusting by using the expensive vacuum method - although the easy hydrolyzability of hemicelluloses is known was (Oesterr "Cheiß _e ~ Zeitg.

40, 5 ff (1937), ... ^was the use of

pre-hydrolyzed material by no means obvious. It was, therefore, extremely surprising that this measure, of which the prior art was just leading away, allowed a smooth and easy saccharification of wood and wood-like materials.

The cellolignin which is particularly suitable for the degradation to water-soluble sugars according to the invention is obtained by prehydrolysis of natural cellulose-containing material. Material (wood, straw, bagasse, etc.) with dilute aqueous mineral acid, preferably dilute hydrochloric or sulfuric acid, won. As was already indicated in the description of the prior art, the prehydrolysis is known in wood saccharification and is also found in recent literature such as Ullmanns Encyclopadie der technischen Chemie, 3 * Edition, Volume 8 (1957), pages 591-595 and in the book of V /. Sandermann, "Chemische Hoetzverwertung", Bayrischer Landwirtschaftverlag, Munich 1963, Sc 253 described.

It consists in a relatively short-term treatment of the - natural starting material with a highly diluted mineral acid at elevated temperature (preferably between about 100 and 160 ° C) and elevated pressure '(preferably up to about 10 atm), essentially in the hemicellulose !! contained pentosanceand hexosans to the monomer units (xylose, arabinoso, mannose, etc.)

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be split. Depending on the reaction conditions, these can then be isolated as such or undergo further changes, for example by dehydration to furfurol, etc.

They are preferably used as ferramentation raw materials or for the recovery of xylitol.

Furthermore, hemicellulose-poor waste papers are well suited for use.

The digestion according to the invention can be carried out, for example, by dissolving the material pre-decomposed (cellolignin or aB paper shredder material) either discontinuously into about 20%, advantageously about 2-5S and optionally comminuted, pre-shredded material a suitable stirrer vessel made of hydrogen fluoride - resistant Y / Erkstoff with HF · gas brings into contact, possibly in admixture with air or other inert carrier gas, or that an HF-containing gas mixture advantageously counteracts in a conveyor system a continuous stream of the aufzuschließenden substrate ,

By spontaneously freiwerdonde heat of reaction, the temperature at and may increase by a suitable reaction procedure such as dilution with inert gases, in the desired range between about 20 to 120 ⁰ C, preferably between 40 and 80- ⁰ C.

The contact of the substrate with hydrogen fluoride gas is maintained for 3Q 'until a weight of part

Katoriafs / 0.2 to 3.0, preferably / Ö; 4 to O ₅ 8, parts by weight of hydrogen fluoride added bat.

Advantageously, the reaction is continued so that, depending on the nature of the substrate and the conditions of the RF absorption, a Verve.Uze it gc-iv / ähl is the üur y-j.1

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Achieving the high yield is sufficient «Longer residence times are not detrimental, but also without advantage. They can be between about 15 minutes and several hours. Preferred are reaction conditions in which the residence time does not exceed 1 hour.

The subsequent HF desorption can in the prior art by heating the reaction mixture and / or by evacuation or by treatment with an inert gas stream (eg nitrogen, air, CO ₂ or noble gas) of suitable strength again with or without simultaneous heating and / or · evacuate, "The thus recovered hydrogen fluoride can be isolated by condensation or reacted directly with fresh substrate v / earth, so that a

T 5 cycle of gaseous hydrogen fluoride comes about. The further work-up of the now digested ("saccharified") material can also be carried out in a manner known per se, such as e.g. described by K. Fredenhagen and Ge Cadenbach; Angewandte Chemie 46_ (1952), Sc 115 to 117 "Extracts, for example, with hot water, filtered from the insoluble lignin, neutralized in the filtrate, the small amount of entrained hydrogen fluoride by means of calcium carbonate or hydroxide and narrows.

The amount of "wood sugar" (or "straw sugar" ¹ etc.) obtained after drying the Eindanvprückückstandos is in the erfindungsgomäßen procedure consistently above about 90 <fo of the cellulose contained in the substrate (calculated on dry matter).

Because of the high "sugar" yield, the extraordinary

simple and smooth Vorfahronsdurchführung (increasing the porosity of the substrate, thereby facilitating the penetration of HF!) also .and 'the einercjiecjünst.U] s ^ _{5-Fluorv.'assersto.nf} Absorpv.ion (no refrigeration necessary, no vacuum) the h'rf'inaunq represents a not inconsiderable port step in this field. ' ¹

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The oligomeric glucose units can be supplied in the resulting form of a further utilization ("fermentation to ethanol, concentration or evaporation and use as cattle feed additives or as Permentationsrohstoffe etc) or in a conventional manner of a Tiachhydrolyse be subjected to monomeric glucose.

From e i s ρi e 1

The invention will now be explained in more detail by the following examples:

example 1

In a round 2 1 vessel made of transparent polyethylene with stirrer, thermometer and gas inlet 500 g Pichtenholz-Oellolignin (59 % cellulose + 41 % lignin) of about 2 mm grain size were submitted and with a mixture of air and hydrogen fluoride gas, which is by passing air over liquid hydrogen fluoride at 20 ⁰ C (water bath) produces, treated. The material was stirred slowly and turned dark brown. »The air flow and the HP evaporation were adjusted so that the internal temperature did not exceed 70 ^° C.,

After uptake of 300 g of hydrogen fluoride was maintained for 30 min to maintain an internal temperature of 50 ⁰ C, with further stirring, the hydrogen fluoride was then expelled by the introduction of hot air. Part of the necessary heat of desorption was also applied by external heating. The desorption was continued under increasing temperature up to a hydrogen fluoride content of about 5 % in the substrate. "Then the material was transferred to a fluidized bed dryer and hydrogen fluoride was blown off to a residual amount of about 0.5%. The resulting HF-air mixtures could be used directly for further approaches.

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Subsequently, the contents of the reactor were digested for 15 minutes with about 2 liters of hot water, filtered off with suction and washed with a little water. The dark brown residue weighed filter after drying, about 250 g, and thus consisted of 82 fi of lignin as well as $ 18 from undigested cellulose. The filtrate was made alkaline with technical calcium hydroxide still hot, neutralized the Ilydroxylionenüberschuß with carbon dioxide, and the Calciurnf luorid and carbonate, evt, with the aid of a Filtrationshi.lfamittels filtered off. The clear pale yellow _t, neutral solution was brought j _rn vacuo to dryness. About 250 g of pale yellowish wood sugar were obtained, corresponding to a yield of 85% of theory. The product was clearly soluble in water and contained between 2 and 10 ⁽ ρ monomeric glucose, the host was oligomeric glucose «

A jacketed, hydrogen fluoride-resistant tube of 30 cm in length and 4 cm in height was filled at about half height in horizontal position with 30 g of cellolignin of grain size 1 to 2 mm, and closed at both ends with pierced rubber cuttings , In the cellulite, as well as in the free space above, there was a thin perforated steel tube perforated along the entire length. These tubes lead on both sides through holes in the plug to the outside and were used to supply and / or discharge of HF-air mixture. In this way, it was possible to gas the cellolignin vertically to the surface of the bed. It was düs material absorb hydrogen fluoride and provided during the subsequent residence time by appropriate heating for an internal temperature of 50 ^L! C <Subsequently, instead of the HF- / M

Air mixture was blown through the bed 15 min long hot air and worked up the thus obtained, freed from the main amount of hydrogen fluoride reaction mixture, as described in Example 1

 5

The following table shows the yields as a function of absorbed HF quantity and residence time «

Example HF absorbs residence time. Yield of No. £ ~ & J / Jni-lß / wood sugar

^c /> d.Th.

2 9

3 11 15 4 15

5 16

6 17.

7 19 6 20

20 9 19

10 19

11 19

12 19

13 '19

120 4 24 120 6 35 120 9.5 56 120 11 65 120 12 71 120 15 88 120 16 94 10 11 65 20 13 77 25 14 82 30 15 80 60 15 88

pJjI _-1 14

Horizontally arranged in Europe, long tube made of hydrogen fluoride - resistant material, in which a r.iesel-. capable solid continuously moved by means of screw conveyor. a cllllolignin filling was made into an olive oil Trügorgasgcmir.ch deio-stalt

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counteracted that the material at the HF inlet end of the tube has a content of about 60 ^c p HF, based on Celloligniiif aufj, _it on the cellolignin inlet end, however, only pure carrier gas flows out The reaction mixture was discharged continuously at the HF inlet end, while on the The discharged Materialwurdo freed after passing through a 30-minute Verwcilzeitstrecke by blowing off the hydrogen fluoride and returned the resulting high-HF gas mixture in the reaction tube The workup of the digested Celloligriins was carried out in the example already described in Example 1. The yield of wood sugar is about 85 ^c / o d.Th.

Example 15

Newspaper paper of newsprint was gassed in the manner described in more detail in Example 1 with a mixture of hydrogen fluoride and air. After standing for 20 hours

let the reaction mixture ^ at 50 ⁰ C, the hydrogen fluoride hydrogen was removed by introducing a v / armluftstromes to a residual content of 2% and the dark colored residue digested with hot water. After filtering and

Drying resulted in 50 g of insoluble material, 25

mainly consisting of lignin »The filtrate was neutralized with hydrated lime and filtered off with calcium fluoride. The Eindrrprückstand of the filtrate weighed 00 g and. contains about 10 % raonomore glucose (rest: oligomore

Glucose) * 30

Claims (3)

23. 3. 1982 AP C 13 K / 234 420 59 894 18 ~ 16 - He f indtm ^ san s ρ ru ch 1, "A process for obtaining water-soluble saccharides from cellulosic material by treating it with gaseous - possibly diluted with an inert gas - hydrogen fluoride at temperatures between about 20 and 120 ⁰ C, preferably between about
40 and 80 ⁰ C, characterized in that subjecting Cellolignin treatment with hydrogen fluoride, 2 »Process according to item 1, characterized in that as cellolignin obtained by prehydrolysis of natural cellulose-containing material with dilute mineral acid at elevated temperature and elevated pressure
Material used. 3. The method according to item 1, characterized in that used as cellolignin low-hemicellulose waste papers *