Classifications

• • C—CHEMISTRY; METALLURGY
  • C13—SUGAR INDUSTRY
  • C13K—SACCHARIDES OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DISACCHARIDES, OLIGOSACCHARIDES OR POLYSACCHARIDES
  • C13K1/00—Glucose; Glucose-containing syrups
  • C13K1/02—Glucose; Glucose-containing syrups obtained by saccharification of cellulosic materials

Definitions

• Cellulose-containing materials are found in nature in large numbers and diversity.
• a known such natural cellulosic material is e.g. 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 recycling of wood is done in a variety of ways, e.g. B. for heat generation (firing), as a building material in the furniture and building materials sector, etc.; Purely chemical recycling of the wood is also possible.
• Chemical digestion processes that not only separate wood into its components, hemicellulose, cellulose and lignin, but also break it down and transform it, have long been known.
• the chemical processes generally provide aqueous solutions of mono-, di- and oligomeric saccharides, which may be subjected to post-hydrolysis to glucose or directly fermented to ethanol, concentrated or evaporated to dryness.
• Possible areas of application for products obtained in this way include: B. in the field of animal feed additives or preferably that of fermentation raw materials.
• CH patent 246773 relates to a minor modification of the Scholler process.
• Very dilute aqueous acid mixtures are allowed to act on native material (e.g. wood).
• these acid mixtures can also contain sulfuric acid and / or hydrohalic acids (including HF as aqueous hydrofluoric acid).
• British Patent Specification 271 410 describes a process in which the action of 10% aqueous sulfuric acid or aqueous bisulfate on wood is followed by a drying process and thus a concentration of the sulfuric acid at 100-1200C.
• This now relatively concentrated aqueous sulfuric acid-containing reaction mixture is z.
• DE-C-560 535 describes the digestion of wood with liquid or vaporous pure HF at low temperatures, the HF being recirculated by evaporation or blowing off and subsequent condensation.
• DE-C-585 318 describes a process for the digestion of wood with gaseous hydrogen fluoride, which involves three stages by absorption of HF on wood at 10 ° -20 ° G, the digestion at 20 ° -50 ° C and the desorption works at 100 ° -150 ° C, where the HF can be diluted with an inert gas stream.
• the cooling effort for the condensation of HF has a disadvantage here, as does the fact that when condensation occurs, only a very uneven distribution of the hydrogen fluoride on the reaction material occurs, a circumstance which can only be counteracted by very long dwell times or a sharp increase in the use of hydrogen fluoride otherwise the yields can be severely impaired.
• DE-C-606009 describes an extraction with liquid HF, which, however, requires large quantities of HF and is disadvantageous in that large amounts of heat are added to the evaporation of the hydrogen fluoride from the extract and extraction residue (lignin) and during the subsequent one Condensation must be removed again.
• a further problem is the separation of the acetic acid formed during the hydrolysis of hemicellulose, which makes it as difficult as possible to circulate the HF without loss, and the easy decomposition of the pentoses to furfural.
• C ellolignin here means vegetable materials such as wood, straw, bagasse and similar raw materials that have been subjected to a pre-hydrolysis known per se.
• reaction material is significantly easier to handle in terms of process technology.
• this is due to the fact that cellolignin has a bulk volume of only about half that of wood of the same grain size and thus has a significantly smaller degree of shrinkage when digested with hydrogen fluoride gas.
• B. means a great relief for the dimensioning of reactors.
• reaction material made of cellolignin remains pourable and free-flowing even when it is loaded with hydrogen fluoride, whereas that made from native wood tends to stick together due to resinous accompanying substances, as well as cleavage products of the hemicelluloses, and is difficult to convey.
• Another advantage is the possibility of absorption of HF on cellolignin above the boiling point of HF, so that external cooling is no longer necessary. It was also surprising that in the process according to the invention yields of> 90% glucose or oligomeric glucose, based on the cellulose used in the cellolignin, are achieved in a simple manner, the resulting sugars being of high quality, i.e. H. are almost colorless.
• the subject of the invention is therefore a process for obtaining water-soluble saccharides from cellulose-containing material by treating the same with gaseous hydrogen fluoride, optionally diluted with an inert gas, at temperatures between about 20 and 120 ° C., preferably between 40 and 80 ° C., characterized in that cellolignin , a material consisting largely of cellulose and lignin, essentially free of pentosans and hexosanes and obtained by prehydrolysis of natural cellulose-containing material with dilute mineral acid at elevated temperature and pressure, which is subjected to treatment with hydrogen fluoride.
• the cellolignin which is particularly suitable according to the invention for degradation to water-soluble sugars is obtained by pre-hydrolysis of natural cellulose-containing material (wood, straw, bagasse, etc.) with dilute aqueous mineral acid, preferably dilute hydrochloric or sulfuric acid.
• Prehydrolysis is - as already indicated in the description of the prior art - known in wood saccharification and consists in a relatively short-term treatment of the natural starting material with a highly dilute mineral acid at elevated temperature (preferably between about 100 and 160 ° C) and increased pressure (preferably up to about 10 bar), essentially splitting the pentosans and hexosans contained in the hemicelluloses down to the monomer units (xylose, arabinose, mannose etc.). Depending on the reaction conditions, these can then be isolated as such or undergo further changes, e.g. B. by dehydration to furfural.
• the digestion with hydrogen fluoride according to the invention can be accomplished, for example, in such a way that the cellolignin, which has been dried to a moisture content of 0 to about 20%, advantageously about 2 to 5% and comminuted as required, is either discontinuously in a suitable stirred vessel made of hydrogen fluoride-resistant material Bring HF gas in contact, optionally in a mixture with air or another inert carrier gas, or that an HF-containing gas mixture is advantageously guided towards a continuous flow of the substrate to be digested in a conveyor system.
• the contact of the substrate with hydrogen fluoride gas is maintained until one part by weight of the material has absorbed about 0.2 to 3.0, preferably about 0.4 to 0.8, part by weight of hydrogen fluoride.
• the reaction is now advantageously carried out in such a way that, depending on the type of substrate and the conditions of the HF absorption, a residence time is selected which is sufficient to achieve the high yield.
• Longer dwell times are not disadvantageous, but they are also of no advantage. They can be between about 15 minutes and several hours. Reaction conditions in which the residence time does not exceed about 1 hour are preferred.
• the subsequent HF desorption can, according to the prior art, be carried out by heating the reaction mixture and / or by evacuation or by treatment with an inert gas stream (for example nitrogen, air, CO 2 or noble gas) with or without a suitable starch Heating and / or evacuation.
• an inert gas stream for example nitrogen, air, CO 2 or noble gas
• the hydrogen fluoride recovered in this way can be isolated by condensation or reacted directly with fresh substrate, so that a cycle of gaseous hydrogen fluoride is formed.
• the further processing of the now digested ("saccharified " ) material can also be carried out in a manner known per se, as described, for example, by K. Fredenhagen and G. Cadenbach, Angewandte Chemie 46 (1933), pp. 113 to 117 Extracts with hot water, for example, filters off the insoluble lignin, neutralizes the small amount of hydrogen fluoride carried in the filtrate by means of calcium carbonate or hydroxide and concentrates.
• the amount of "wood sugar (or” straw sugar " etc.) obtained after drying the evaporation residue is consistently over about 90% of the cellulose contained in the substrate (calculated on dry substance) in the process according to the invention.
• the invention does not constitute one insignificant progress in this area.
• the oligomeric glucose building blocks can be subjected directly to further utilization (fermentation to ethanol, concentration or evaporation and use as animal feed additives or as fermentation raw materials etc.) or also in a manner known per se to post-hydrolysis to monomeric glucose.
• spruce wood cellolignin 59% cellulose + 41% lignin
• a grain size of approx. 2 mm 500 g were placed in a round 2 liter vessel made of transparent polyethylene with a stirrer, thermometer and gas inlet and mixed with a mixture of air and hydrogen fluoride gas prepared by passing air over liquid hydrogen fluoride at 200C (water bath) treated.
• the material was slowly stirred and turned dark brown.
• the air flow and HF evaporation were regulated so that the internal temperature did not exceed 70 ° C.
• the reactor contents were then digested for 15 minutes with about 2 l of hot water, suctioned off sharply and washed with a little water.
• the dark brown filter residue weighed about 250 g after drying and thus consisted of 82% lignin and 18% undigested cellulose.
• the filtrate was made alkaline while still hot with technical calcium hydroxide, the excess hydroxyl ion was neutralized with carbon dioxide, and the calcium fluoride and carbonate were filtered off, possibly with the aid of a filtration aid.
• the clear, pale yellow, neutral solution was brought to dryness in a vacuum. This gave about 250 g of slightly yellowish wood sugar, corresponding to a yield of 85% of theory. Th.
• the product was clearly water-soluble and contained between 2 and 10% monomeric glucose, the rest consisted of oligomeric glucose.
• the following table shows the yields as a function of the amount of HF absorbed and the residence time.
• a cellolignin filling was countered with a mixture of hydrogen fluoride and carrier gas in such a way that the material at the HF inlet end of the tube had a content of approx Had 60% HF, based on cellolignin, but only a pure carrier gas flowed out at the cellolignin inlet end.
• the reaction material was continuously discharged at the HF inlet end, while fresh cellolignin was supplied on the opposite side.
• the discharged material was freed from hydrogen fluoride by blowing off after passing through a half-hour residence time and the HF-rich gas mixture thus obtained was returned to the reaction tube.
• the digested cellolignin was worked up in the manner already described in Example 1. The yield of wood sugar was approx. 85% of theory. Th.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• General Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Emergency Medicine (AREA)
• Biochemistry (AREA)
• Health & Medical Sciences (AREA)
• Polysaccharides And Polysaccharide Derivatives (AREA)
• Saccharide Compounds (AREA)
• Processing Of Solid Wastes (AREA)
• Medicines Containing Material From Animals Or Micro-Organisms (AREA)
• Absorbent Articles And Supports Therefor (AREA)
• Jellies, Jams, And Syrups (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)

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Publications (2)

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• 1980
  • 1980-10-30 DE DE3040850A patent/DE3040850C2/de not_active Expired
• 1981
  • 1981-10-24 DE DE8181108878T patent/DE3176031D1/de not_active Expired
  • 1981-10-24 EP EP81108878A patent/EP0051237B1/de not_active Expired
  • 1981-10-24 AT AT81108878T patent/ATE26129T1/de not_active IP Right Cessation
  • 1981-10-28 DD DD81234420A patent/DD208173A5/de not_active IP Right Cessation
  • 1981-10-28 PH PH26410A patent/PH17341A/en unknown
  • 1981-10-28 FI FI813370A patent/FI813370A7/fi not_active Application Discontinuation
  • 1981-10-28 NZ NZ198780A patent/NZ198780A/en unknown
  • 1981-10-29 PL PL23362181A patent/PL233621A1/xx unknown
  • 1981-10-29 ZA ZA817493A patent/ZA817493B/xx unknown
  • 1981-10-29 DK DK478381A patent/DK478381A/da not_active Application Discontinuation
  • 1981-10-29 JP JP56172177A patent/JPS57105200A/ja active Pending
  • 1981-10-29 CA CA000389579A patent/CA1181397A/en not_active Expired
  • 1981-10-29 BR BR8107016A patent/BR8107016A/pt unknown
  • 1981-10-29 AU AU76942/81A patent/AU7694281A/en not_active Abandoned

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