JPS5929240B2 - Method for producing xylose - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing xylose by hydrolysis of a raw material containing bentosan, preferably xylan, followed by purification and chromatographic fractionation methods.

There are a number of methods published so far as suitable for obtaining xylose and/or xylit from natural products such as birch trees, corn cobs, cotton seed husks, etc.

Leihin, E.R. and Tuboleva, G.D.
Russian editorial published by C, D): Proizvostro Ksirita
l ita ) (production of xylitol) is an overview of previously known methods.

Recent US patents that address the above issues are US Patent Nos. 3,212,932 and 3,558,725.

British Patent No. 1,209,960 and Russian Patent No. 167,845 (1965) also disclose related technology.

However, prior art methods are rarely utilized on a commercial scale due to their economic disadvantages.

For example, when producing a xylose-rich solution from wood chips by prior art methods, the resulting solution is so impure that many costly operational steps are required before pure xylose can be recovered.

According to the present invention, an improved process for producing xylose from bentosan-containing, in particular xylan-containing feedstock materials has now been developed.

In the process, a pentose-rich solution obtained by oxidative water splitting of a bentosan-containing raw material is prepurified by mechanical filtration and deionization operations for decolorization and desalting.

The present invention is characterized in that this prepurified pentose solution is subjected to chromatographic fractionation using a specific ion exchange resin to recover a highly pure solution of xylose.

This highly purified xylose solution may be used directly as a xylose source in the form of an aqueous solution, or may be used to crystallize xolose from this solution.

Alternatively, if desired, the solution may be hydrogenated to convert it into a xylit solution, which is then subjected to chromatographic fractionation and used to recover pure xylit.

The method for accomplishing the chromatographic fractionation is to apply the solution to an alkaline earth metal ion form column of polystyrene sulfonate cation exchange resin cross-linked with di-vinylbenzene, and the column is approximately
．． Since it can have a height of 5 to 5 m, the process of the invention is particularly suitable for producing large amounts of xylose.

One of the advantages of the process of the present invention is that it provides a solution of xylose of sufficient purity to hydrogenate it reliably to xylitide on a commercial scale.

The starting material for obtaining the bentosan-enriched solution is preferably wood of various types of trees, such as birch and beech, and other lignocellulosic materials.

Also useful are oat husks, corn cobs and stalks, coconut husks, almond husks, straw, cane lees, and cotton seed husks.

When using wood, it is preferable to crush it into wood chips, shavings, sawdust, etc. before use.

The invention will be further described with reference to the accompanying drawings: FIG. 1 is a flow diagram generally illustrating the method of the invention, and FIG. 2 shows four possible ways of prepurifying a pentose sugar solution according to the invention. 3 is a process diagram showing a method for recovering xylit from a hydrogenated pentose solution. FIG. 4 is a process diagram showing a material balance for a method for producing xylose from wood chips.

In FIG. 1, the hydrolysis of the starting material in the first step of the invention may be carried out by any method known to those skilled in the art.

A suitable method described in the literature is U.S. Pat.
No. 4,836, No. 2,759,856, 2.801,9
39 to No. 2,974,067 and No. 3,212.932.

When selecting an appropriate method of hydrolysis, a key consideration is to obtain the maximum yield of pentose and to ensure that the resulting pentose-rich solution is treated with substances that do not cause dangerous degradation of the sugars, e.g. hydroxylation. Neutralization using sodium.

This hydrolysis product is then prepurified.

The prepurification stage consists of two main steps: the first prepurification stage is to remove the main part of salts (sulfuric acid, sulfuric acid) and organic impurities as well as colored objects by a deionization operation; is the removal of salt from a solution.

The process is used in the sugar industry for the purification of molasses.

Suitable methods are described in U.S. Pat. Nos. 2,890,972 and 2.
No. 937,959.

However, this desalting step may be omitted when using a pentose solution obtained by a method other than acid hydrolysis.

The second pre-purification stage is the stage in which final decolorization is achieved.

That is, when the desalting process is completed, the solution still contains some organic and inorganic impurities and also has coloration due to the impurities.

These are removed in a decolorization step by treating the impure solution with an ion exchange system consisting of a strong cation exchanger followed by a weak anion exchanger, and then passing the solution through an adsorbent or activated carbon bed. .

These methods are also known in the sugar industry.

One such method is, for example, US Pat. No. 35,587
It is described in Specification No. 25, or also Yotsuto.
Stamberg and Forfalter (J, Sta.
Mbergand V, Walter), Ent.
fHrbungsharze.

Academy Verlag Berlin
1970 and P. Smit (P, Smit)
- & Ionenaustau-scher und
Adsorberbei der Hers
-Tellung und Reinigung
von Zuck-ern, Pektine
n und verwandten St -o
ffen, AJcademie Verlag
Berlin.

1969 Nijni Hustler (J, Hassl)
ar), Activated carbon: L
eonard hill london 196
It is also mentioned in the year 7.

As shown in the upper part of Figure 2, the prepurification step may be further improved if necessary by the addition of a step using a synthetic macronetwork adsorbent such as Amberly XAD2 to remove organic impurities.

The macronetwork adsorbent may be used immediately after the deionization step and before treatment with a cation exchanger, as shown in Figure 2, or alternatively it may be used in the final step of the purification step. .

FIG. 2 shows four variants for achieving the prepurification stage of the process of the invention.

The choice of which of these variants depends on the nature and degree of impurities present in the solution and on the composition of the solution to be prepurified.

The prepurified pentose solution obtained in the prepurification step is then subjected to chromatographic fractionation to obtain a solution with high purity with respect to xylose, as shown in Figure 1, and subsequently used to recover xylose by a crystallization operation. can.

The pentose molasses comprising fractions not required in the present invention may be further subjected to chromatographic fractionation to recover one or more of the other sugars present therein.
Alternatively, it may be used as a carbohydrate source for the fermentation industry.

Apart from this, the prepurified pentose solution is
It can also be hydrogenated by the method outlined in FIG. 3 and used to produce xylit.

The hydrogenation process is carried out in a similar manner to the hydrogenation of Brecose to Nruvit.

A suitable method is W, Schneider (W, 5chn
The H.
ydr-generation of Gluco
se to So'rbito-1 with Ra
ney N1ckel Catalyst”.

Example 1 In this example, highly purified xylose is recovered from a xylose-enriched prepurified pentose solution obtained as shown in FIG. 1 by chromatographic fractionation and subsequent crystallization. This is an example.

Although the prepurified pentose solution contains several sugars in addition to xylose, the solution is made highly enriched for xylose by utilizing the chromatographic fractionation technique of the present invention.

To carry out this example, a 1.0 m high and 9.4 Crr10 column consisting of a strongly acidic cation exchanger in the strontium form of the sulfonated polystyrene type crosslinked with 3.5% di-vinylbenzene is prepared.

Immerse the above column in water.

A pentose solution containing 25% solids and having the following composition was used as the feed solution: Sugar, 73% xylose, 6.1% arabinose, 9.0% mannose, 5.1% glucose, 6.8% glucose on a dry solids basis.

The above feed solution is 27rrLt/m from the old capital of the column.
The solids were fed uniformly at a rate of 1.5 in. until a total solids content of 60 g was fed to the column.

The first 108 mt elution fraction, consisting primarily of water originally present in the column, is discarded.

The analysis results of the subsequently eluted fractions are shown in Table H.

By mixing fractions 6, 7 and 8, a solution containing 30.5 r of xylose with a purity of 89 was obtained.

The recovery rate of xylose in this chromatography is approximately 7
I am in charge of 0.

Pure crystalline xylose can be easily produced from both of the xylose-rich components.

Alternatively, if desired, both of the xylose-rich components can be hydrogenated as shown in the lower right corner of FIG. 1 to obtain a Quijirot solution.

Furthermore, it is also possible to crystallize the xylose from an impure solution, such as the feed solution used above in this example, and then fractionate the sugar remaining in the syrup by chromatographic methods using ion exchange resins. .

The xylose-rich fraction thus separated is recycled to the crystallization step.

Other pentoses and hexoses can also be obtained from the corresponding fractions remaining after collecting the xylose fraction, or the two remaining fractions may be combined together to form pentose molasses.

Example ■ Chips of birch wood are used to produce xylose according to the method of the invention.

The material balance table for this example is shown in Figure 4 of the drawings.

According to the method of this example, birch wood chips containing 1.0 OOP of dry matter are hydrolyzed with sulfuric acid to obtain a mixture of melted ice and pulp containing a total of 2251 xylose.

The pulp containing xylan 51f is removed from the ice melt and discarded or used for other purposes.

Xylose 204I? The remainder of the melted ice containing 204f xylose, 110g of organic matter other than xylose, and 67I of inorganic matter were neutralized with sodium hydroxide. Obtain a melted ice product containing.

Next, the melted ice is heated to drive out unnecessary acidic acid and water, and then a desalination process is performed by deionization, and the solution is mixed with a strongly acidic cation exchanger and a weakly basic anion exchanger. A first pre-purification treatment is carried out through a continuous bed (mixed bed).

As shown in the drawing, the main part of the inorganic material mixed with xylose 14f and some organic material are discarded.

The part containing organic impurities and most of the xylose along with a small amount of solids is again subjected to the evaporation process and excess water is removed.

The concentrated sugar solution obtained as above is Sent to pre-purification decolorization step and activated carbon bed.

A solution containing 181 g of xylose and 40 g of xylose is obtained.

A rich purified solution is added to the xylose obtained by hydrolysis of birch wood followed by decolorization treatment as described above.
The solid content of the above-mentioned sugar-rich solution determined by chromatographic analysis was as follows: Sugar Arabinose 6 Xylose 78 Mannose 7. 5 Galactose 5 Glucose 4.5.

The resin used was a strongly acidic cation exchanger, i.e.
It was a sulfonated polystyrene crosslinked with vinylbenzene 3.5 parts, and the resin was used in the calcium form.

The resin had an average particle size of 0.32 mm.

Chromatography was performed at a temperature of 49°C.

The column has a height of 350Crr1 and a diameter of 22.5c.
It was m.

The column was submerged in water.

A solution rich in xylose is 17. It was uniformly supplied to the column at a rate of /, /hr.

Add a solution with a solid content of 26 to a solid content of 4 to 7 to the above column.
We supplied a considerable amount.

The first eluate from the column (88t, consisting primarily of water) was discarded.

Thereafter, serial fractions were collected and analyzed.

The results are as follows: Combining fractions 3 to 6 yields 35t of a xylose-rich solution with the following analysis: sugar
? Arabinose-xylose 2483” Mannose 240 Galactose 108 Glucose 83.

■Purity 85%, recovery rate by chromatography 80%,
Recovery rate for xylan contained in the raw material: 69%Example ■ A xylose-rich prepurified solution obtained by hydrolysis of birch wood followed by desalting and decolorization in the same manner as in Example ■ above was subjected to ion exchange as described below. It was purified by chromatographic fractionation using a resin column.

The solid content composition of the xylose-rich prepurified solution in this example, as determined by gas chromatographic analysis, is as follows: Sugar Arabinose 6.5 Xylose 77 Mannose 8 Galactose 4 Glucose 4.5° Resin used was a sulfonated polystyrene crosslinked with a strongly acidic cation exchanger, 3.5 parts di-vinylbenzene, and the resin was used in the strontium form.

The resin had an average particle size of 0.32 mm.

Chromatography was performed at a temperature of 51°C.

The column had a height of 350 Crn and a diameter of 22.5 mm.

The column was soaked with water. 15% of the above xylose-rich solution
The solids were uniformly fed to the column at a rate of 1/2 hour, and the total amount of solids fed to the column was 4 kg in the form of a solution with a solids content of 28%.

The first eluate from the column (88t and consisting mainly of water) was discarded.

Thereafter, both portions were sequentially collected and analyzed.

The analysis results are 96 times.

Combining fractions 3 to 6 yields a xylose-rich solution with the following analytical results: 35. /, obtained: sugar
? Arabinose-xylose 2385 (=90%) Mannose 124 Galactose 48 Glucose 82.

[Brief explanation of drawings]

FIG. 1 is a process diagram generally illustrating the method of the invention, FIG. 2 is a process diagram illustrating four possible ways to prepurify a pentose sugar solution according to the invention, and FIG. FIG. 4 is a process diagram showing a method for recovering xylose from a hydrogenated pentose solution, and FIG. 4 is a process diagram showing a material balance for a method for producing xylose from wood chips.

Claims (1)

[Claims] 1 a) A pentose-rich solution obtained by acid hydrolysis of a raw material containing bentosan is filtered to remove insoluble materials, and then inorganic salts and most organic impurities are removed by a deionization operation. Colored matter is removed, and residual organic impurities and colored matter are removed by treatment with an ion exchange resin or activated carbon to obtain a pre-purified pentose mixed solution, b) polystyrene sulfonate obtained by crosslinking the hendose mixed solution with divinylbenzene. A method for producing xylose, which comprises recovering highly pure xylose by fractionating it by chromatography using an alkaline earth metal ion type column of cation exchange resin.