WO2013113330A1 - Method for producing valuable substances, in particular arabinogalactan, from wood - Google Patents

Description

 Process for the production of valuable materials, in particular arabinogalactan, from wood

description

The present invention relates to processes for the preparation or isolation of valuable materials from wood, in particular from larch wood. By means of the method u.a. Arabinogalactan produced.

The prior art knows various methods for the production of arabinogalactan and taxifolin (also: dihydroquercetin) from larch wood. However, the previously known methods merely show methods for producing small quantities, in particular for the pharmaceutical industry. These methods are not suitable for economically viable production of large amounts of these recyclables.

It is an object of the present invention to provide methods which allow cost-effective and environmentally sound implementation of the economic production of pure arabinogalactan as possible from wood.

The solution of this object is achieved by the features of the independent claims. The dependent claims have preferred developments of the invention to the subject. Thus, the object is achieved by a method for producing at least two valuable substances. One of the valuable substances is arabinogalactan (second valuable substance). Another valuable material (first valuable substance) is for example Taxifolin. The process comprises the following steps in a given sequence: First, wood particles are coated in a percolator. Preferably larch wood is used here. Particularly preferred are wood particles of the lower stem area and / or the rootstock of the larch, in particular the Siberian larch (larix sibirica / larix dahurica) used. The reason for this is the high content of taxifolin and arabinogalactan in the root section and / or the rootstock of the larch. In particular, cattle wood, sapwood and branch wood are removed and not extracted. After the wood particles have been coated in the percolator, the wood particles are extracted with an organic solvent, preferably ethanol, to dissolve the first valuable substance. The resulting liquid extract is referred to as organic extract, preferably ethanolic extract. Accordingly, the process is referred to as organic extraction, preferably ethanolic extraction. As will be described, the first valuable substance is preferably taxifolin. After extraction with the organic solvent, the organic extract is removed from the percolator. The wood particles remain in the percolator and are extracted following the organic extraction, preferably ethanolic extraction, with water. In this aqueous extraction, arabinogalactan is dissolved from the wood particles. The advantage of the upstream organic extraction, preferably ethanolic extraction, is that resins, oils and various other hydrophobic recyclables are dissolved out of the wood here. The aqueous extract with the dissolved arabinogalactan is thus much purer than when the wood particles are extracted directly with water. This simplifies a purification of the aqueous extract for isolating the arabinogalactan. After the aqueous extraction, removal of the aqueous extract from the percolator followed by purification of the aqueous extract to produce arabinogalactan. Preference is given to steaming the wood particles in the percolator with water vapor before extraction with water. This evaporation serves to remove the residual organic solvent in the percolator. For extraction, it is preferred to use only water without further additives. The water is preferably introduced into the percolator at a temperature between 70 ° C and 95 ° C, preferably between 85 ° C and 95 ° C. After the aqueous extract has been removed from the percolator and before the purification process, the aqueous extract is concentrated by evaporation. The temperature and pressure conditions in the evaporation are chosen so that the water content is reduced in the aqueous extract. Preferably, the evaporation is carried out at a temperature above 65 ° C and reduced pressure. Preferably, it is concentrated to a concentration between 100 and 300 g / L (grams per liter) of arabinogalactan.

For purifying the aqueous extract, precipitation of the arabinogalactan in ethanol is preferably carried out. In this case, the ethanol is colder than the aqueous extract. The aqueous extract is grafted into the ethanol and / or sprayed. Advantageously, ethanol is used at a concentration of at least 70%, preferably at least 80%, more preferably at least 95%. The higher the concentration, the better the arabinogalactan precipitates in the ethanol. It is particularly preferred that the precipitation, the ethanol to 0 ° C to 15 ° C, preferably 0 ° C to 10 ° C, cooled. Furthermore, it is preferably provided that the aqueous extract is heated to a temperature between 16 ° C and 25 ° C prior to precipitation in cold ethanol. The temperature of the extract should ideally be the same as that of the ethanol. A possible temperature difference of no more than 20 ° C results from the assumption that the extract is still cooled during precipitation.

Following precipitation of the arabinogalactan, the precipitate (arabinogalactan) is separated from the mother liquor and washed. The washing is done by adding ethanol to the separated, precipitated arabinogalactan. The remaining water goes into solution with the ethanol or the remaining ethanol is rinsed out. After washing, the mother liquor is again removed. Preferably, this washing process is carried out several times, wherein ethanol is fed to the arabinogalactan always after separation of the mother liquor and in turn the mother liquor is discharged. The washing is carried out until the water content in arabinogalactan is below 25%, preferably below 20%. The experiment has shows that arabinogalactan can be dried relatively well with this water content and prevents agglomeration during drying.

In the washing process, ethanol is preferably used with a concentration of at least 80%, particularly preferably at least 95%. The higher the concentration, the better the water can be bound during the washing process. It is particularly preferred that, for washing, the ethanol is cooled to 0 ° C to 15 ° C, preferably 0 ° C to 10 ° C. After the washing process, drying of the arabinogalactan preferably takes place under conditions of temperature and pressure which permit simultaneous evaporation of water and ethanol. In particular, it is dried under protective gas at a temperature between 40 and 80 ° C. The drying is advantageously carried out at reduced pressure.

As already mentioned, taxifolin is preferably extracted before the aqueous extraction. Ethanol is preferably used for extraction, preferably with a concentration of at least 70%, preferably at least 80%, particularly preferably at least 95%. In order to dissolve a residual extract, it is preferable to apply a negative pressure to the percolator and to rinse the wood particles in the percolator with fresh ethanol and to subsequently combine the ethanolic extracts.

Before purifying, the ethanolic extracts are evaporated by evaporation, preferably to a concentration between 50 and 250 g / L (grams per liter) of taxifolin. The temperature and pressure conditions during the evaporation are chosen so that the ethanol content in the ethanolic extract is reduced. Preferably, the evaporation is carried out at a temperature between 55 ° C and 70 ° C and reduced pressure. The subsequent purification process has the following preferred further steps:

The production of the mixture of water and the ethanolic extract is preferably carried out at a temperature between 70 ° C and 95 ° C. This makes the mixture good pre-tempered for mixing. Directly before and / or during the mixing of the mixture is preferably carried out a reduction of the ethanol content in the mixture by evaporation. Advantageously, the mixing of the mixture takes place actively, preferably by means of an agitator. For optimal dissolution of the taxifoline in the aqueous phase, a temperature range during mixing between 70 ° C and 99 ° C, preferably between 70 ° C and 95 ° C, particularly preferably between 80 ° C and 95 ° C, was found to be advantageous. Directly before and / or during the mixing of the mixture, further water is preferably added to the mixture. In particular, at least the same amount of water is mixed in as mixture is still present after the evaporation of the mixture.

After mixing, the deposition of the resin phase (lower phase) from the water phase (upper phase) and the oil phase (uppermost phase) by cooling the mixture to below 65 ° C. Preferably, the mixture is cooled for at least 30 minutes from 70 ° C to 99 ° C while mixing at 35 ° C to 64 ° C. After cooling, the resin phase is separated from the mixture, and preferably at least a single return of the resin phase in the mixture before cooling. Preferably, the resin phase is recycled to the mixture before and / or during the above-mentioned mixing. After the resins have been recycled at least once, the phase of the resin is removed and the oil phase is separated and removed from the aqueous phase. In the next step, the addition of taxifolin seed crystals to the water phase and cooling to crystallization of the taxifolin occur. This is followed by separating the crystallized Taxifolins from the mother liquor and discharge of the mother liquor.

Preferably, at least one renewed crystallization is then carried out with the following steps in the given order: dissolution of the crystallized taxifoline separated from the mother liquor in water at 70 ° C. to 99 ° C., addition of taxifolin seed crystals, tempering of the water to 0 ° C. to 30 ° C. ° C to crystallize the taxifolin, separating the recrystallized taxifoline from the mother liquor, and removing the mother liquor. It is preferably provided that the initial and / or recrystallization, the addition of the Taxifolinimpfkristalle at a first temperature of the water between 30 ° C and 65 ° C, preferably between 45 ° C and 60 ° C, takes place, and the water to crystallize a second temperature between 0 ° C and 30 ° C, preferably between 20 ° C and 10 ° C, is tempered. The cooling from the first temperature to the second temperature is preferably carried out for 5 to 15 hours. Particularly advantageous for the crystallization is holding the second temperature for 0.5 to 2 hours.

After crystallization, washing of the crystallized taxifolin with cold water (below 50 ° C) and drying of the washed taxifolin.

The invention further comprises a process for producing arabinogalactan, comprising the following steps in a given order: As in the process described above, wood particles, preferably larch wood, are also coated in a percolator. Without a previous organic extraction, the arabinogalactan is dissolved directly here by means of water. This is followed by removal of this aqueous extract from the percolator and purification of the aqueous extract to produce arabinogalactan. As described above, when purifying, at first precipitation of arabinogalactan takes place by spraying and / or dropwise addition of the aqueous extract in ethanol. Subsequently, the precipitated arabinogalactan is separated from the mother liquor and washed. The washing is carried out by adding ethanol, so that residual water goes into solution with the ethanol. After the addition of ethanol, the washed arabinogalactan is separated from the mother liquor. Preference is also given here to carry out the washing process several times until the water content in the arabinogalactan is below 25%, preferably below 20%, so that drying is readily possible. The advantageous embodiments and subclaims presented in the context of the first method according to the invention accordingly find advantageous application to the second method according to the invention. The only difference is that in the second process according to the invention, the organic extraction, preferably ethanolic extraction, is omitted. In all procedures described, both in the extraction and in the purification to the end products taxifolin and arabinogalactan, preferably only water and ethanol are used. Preferably neither the wood nor any of the extracts or the taxifolin or arabinogalactan is treated with substances other than water or ethanol. This avoids any contamination of the taxifolin.

Hereinafter, experiments and an embodiment of the method according to the invention will be explained with reference to the accompanying drawings. Showing:

1 shows a sequence of extraction according to the method of the invention,

2 shows a sequence of the purification of taxifolin according to the invention

 Method, and

3 shows a sequence of the purification of arabinogalactan according to the inventive method.

Fig. 1 shows the steps S1 to S12 for the extraction of larch wood. FIG. 2 shows steps S13 to S28 for purifying the taxifolin, and FIG. 3 shows steps 29 to 34 for purifying arabinogalactan.

The starting material is the lower trunk portion of the larch, in particular the siberian larch {Larix sibirica), in particular the Larch from the German Archipelago (Larix dahurica), in particular Larix spp. used. In step S1, the wood is shredded. This is done in particular by means of a hacker and / or a hammer mill. In step S2, a layering of the comminuted wood particles in a percolator takes place. In step S3, ethanol is introduced into the percolator. In particular, the ethanol is introduced into the top of the percolator and collected at the bottom. Through a pump, the ethanol is pumped through the percolator several times. In step S4, the ethanolic extract obtained is removed from the percolator and an evaporation of the ethanolic extract takes place in step S5. In this case, a part of the ethanol is evaporated. In step S6, the concentrated ethanolic extract is transferred to step S13 (see FIG. 2).

Furthermore, FIG. 1 shows, with step S7, an evaporation of the wood particles in the percolator. After step S4, the wood particles remain in the percolator and the vapor deposition according to step S7 is carried out to reduce the residual ethanol in the percolator. In step S8, an aqueous extraction of the wood particles takes place in the percolator. Again, preferably by pumping the water pumped through the percolator several times. In step S9, the aqueous extract is discharged from the percolator and subjected to evaporation in step S10. This water is evaporated. After step S10, a transfer of the concentrated, aqueous extract to step S30 in FIG. 3 takes place in step S1 1.

After the aqueous extraction according to step S8, the wood particles are discharged from the percolator in step S12. The discharged wood particles represent a usable by-product, namely biomass.

At the beginning of the purification of the ethanolic extract to obtain taxifolin, a change of the solvent takes place. In step S13, the ethanolic extract is mixed with water and re-evaporated in step S14. The temperature and pressure conditions in step S14 are chosen so that primarily ethanol evaporates. In step S15 water is again supplied and an active mixing takes place, preferably with an agitator, so that the taxifolin goes from the resins into the water into solution. This is also referred to as an aqueous resin extraction or a liquid / liquid extraction in step S15. The mixing in step S15 is preferably carried out at the same or higher temperature than the evaporation in S14.

In step S16, the mixture of S15 is cooled. In particular, it is cooled over a longer time, so that the resin phase settles in the mixture. As a result of this cooling, the mixture separates into a resin phase (lower phase) and into a liquid phase (upper phase). In this upper phase are at the top oils and between the resin phase and the oils is an aqueous phase. In step S 7, the oils and the aqueous phase are separated from the resin. The Resin is again returned to step S15. This recycling of the resins is carried out at least once. After the second cycle, the resins are removed. The upper phase, consisting of oils and the aqueous phase from both cycles, is separated in step S18. The oils are removed. The remaining aqueous extract is further processed by crystallization processes and washing in the following steps.

In step S19, taxifolin seed crystals are added to the aqueous phase. In step S20, it is slowly cooled so that the taxifolin crystallizes out. The mother liquor is removed in step S21 and the crystallized taxifolin is re-mixed with water in step S22. In this case, an elevated temperature is selected so that the taxifolin goes into solution again in the water. In step S23 cooling takes place and in step S24 an addition of taxifolin seed crystals takes place. In step S25 is further cooled slowly, so that the taxifolin crystallized out. In step S26, the mother liquor is again discharged and the crystallized taxifolin can be washed in step S27. The washing is done with the addition of cold water. This is followed by drying in step S28, preferably under protective gas. After drying, up to 95% pure taxifolin is obtained.

3 shows the purification of the aqueous extract to obtain arabinogalactan. In step S29, ethanol is cooled. In step S30, the aqueous extract is dripped into the cooled ethanol. At the same time, mixing or stirring of the ethanol takes place in step S31. In step S32, the mother liquor is discharged, so that the precipitated arabinogalactan is separated. The separation takes place at the same temperature as the precipitation, so that the residual water does not lead to the clumping of Arabinogalactans. In particular, the separation in step S32 is carried out at a temperature below 10 ° C.

In step S33, the precipitated arabinogalactan is washed with the cooled ethanol from step S29. The resulting mixture is again separated in step S34 into a mother liquor and arabinogalactan. In steps S35 and S36, a new washing and separation takes place. In step S37, the arabinogalactan is dried to finally produce arabinogalactan with a purity of over 95%. Thanks to the previous ethanolic extraction of the wood particles, arabinogalactan is largely free of impurities. The end product thus contains only a small proportion of water and a low ethanol content, but no further significant impurities in addition to the arabinogalactan.

The following experiment was carried out: 650 kg crushed larch wood was extracted with 4000 liters of 96% ethanol. The ethanolic extract was filtered and evaporated to determine the dry matter dissolved from the wood. With the 4000 liters of ethanol 22kg of dry matter was released from the wood. The upstream ethanolic extraction thus freed the wood from 22kg of hydrophobic substances, resins and oils. With the subsequent aqueous extraction and the purification of arabinogalactan (as described above) arabinogalactan could be produced with a purity of over 95%. The arabinogalactan content was determined based on the known molecular weight. The remaining, just under 5% consisted of water and ethanol. The water content was determined by the Karl Fischer method. The ethanol content was determined with a chromatograph.

Claims

claims Process for the preparation of a first valuable substance and a second valuable substance, namely arabinogalactan, comprising the following steps in a given order:  Layering of wood particles in a percolator,  Extracting the wood particles in the percolator with an organic solvent, preferably ethanol, for dissolving the first valuable substance, removing the organic extract, preferably ethanolic extract, from the percolator,  Extract the wood particles in the percolator with water to dissolve arabinogalactan after the organic extraction,  Removing the aqueous extract from the percolator, and purifying the aqueous extract to produce arabinogalactan. A method according to claim 1, characterized by steaming the wood particles in the percolator with water vapor prior to extraction with water to remove the organic solvent. Method according to one of the preceding claims, characterized in that for extracting water at a temperature between 70 ° C and 95 ° C, preferably between 85 ° C and 95 ° C, is used. Method according to one of the preceding claims, characterized by concentrating the aqueous extract by evaporation before purification. Method according to one of the preceding claims, characterized by precipitation of arabinogalactan by spraying and / or dropwise the aqueous extract in ethanol, and separating the precipitated arabinogalactan from the mother liquor, at the beginning of the purification. A method according to claim 5, characterized by washing the separated, precipitated arabinogalactan by adding ethanol so that residual water goes into solution with the ethanol, and separating the washed arabinogalactan from the mother liquor. 7. The method according to claim 6, characterized by repeated washing by adding ethanol and separating the washed arabinogalactan from the mother liquor until the water content in the washed arabinogalactan is below 25%, preferably below 20%. 8. The method according to any one of claims 5 to 7, characterized in that for precipitation and / or washing ethanol with a concentration of at least 70%, preferably at least 80%, particularly preferably at least 95%, is used. 9. The method according to any one of claims 5 to 8, characterized in that for precipitation and / or washing ethanol at a temperature between 0 ° C and 15 ° C, preferably between 0 ° C and 10 ° C, is used. 10. The method according to any one of claims 5 to 9, characterized in that when precipitating between the aqueous extract and the ethanol there is a temperature difference of not more than 20 ° C. 1. A process for the preparation of arabinogalactan, comprising the following steps in given order:  Layering of wood particles in a percolator,  Extract the wood particles in the percolator to dissolve arabinogalactan  Removing the aqueous extract from the percolator, and purifying the aqueous extract to produce arabinogalactan, comprising the steps of:  Precipitating arabinogalactan by spraying and / or dropping the aqueous extract in ethanol, and separating the precipitated arabinogalactan from the mother liquor, and Washing the separated, precipitated arabinogalactan by adding ethanol such that residual water goes into solution with the ethanol, and separating the washed arabinogalactan from the mother liquor.