JP2979125B2 - Xylose production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention industrially produces high-purity xylose inexpensively and efficiently by applying a specific hydrolysis condition using a core layer of babassu shell as a raw material. On how to do it.

[Related Art] Conventionally, xylose is a natural plant material containing a large amount of cellulose and various hemicellulose in addition to xylan (for example, monocots such as oats, corn or cottonseed hulls, and beech, poplar, and hippo). Starting from dicotyledonous plants such as deciduous trees) and waste organic raw materials of the pulp and paper industry (waste such as sulfite pulp, kraft pulp and semi-chemical pulp) as starting materials, hydrolysis with mineral acids, organic acids or enzymatic agents Have been attempted. In addition, since these hydrolysates contain impurities such as various kinds of sugars,
For the purification, a method such as fermentation removal of impurities by yeast has been used.

[Problems to be Solved by the Invention] Since these starting materials are generally composed of various polysaccharides, the obtained hydrolyzed sugar solution contains pentoses such as arabinose and the like in addition to the target xylose. Hexasaccharides such as glucose, mannose and galactose and acetic acid are produced.

Therefore, it is extremely difficult to separate each component from this mixture to recover xylose with high purity, which requires much cost and time.

On the other hand, as a method for producing xylose free from the contamination of other impurities as described above, there is a method using an outer shell layer or a core layer of babasi palm as a raw material and using an enzyme agent (JP-B-56-50960). However, according to this method, there is a post-treatment for separating the enzyme hydrolyzate into a polyanionic substance which is an acidic component containing xylose and uronic acid, which are neutral components, together with a pre-treatment step such as delignification or alkali extraction of xylan. In order to obtain only xylose, there are problems that the process is complicated and that it is expensive and time-consuming.

In general, the use of natural products as raw materials poses a problem in the stability of raw material supply. For example, when using cottonseed husk as a raw material (Japanese Patent Publication No. 43-12237), the use value of cottonseed oil decreases. There is a problem in the stable supply of raw materials in the future. In a plant used as a raw material, the state of xylan varies depending on its origin, and its behavior with respect to heat and chemicals also differs depending on the molecular weight of xylan itself and the state of binding to lignin / cellulose.

As a raw material for the production of xylose, the core layer of the babassu coconut shell is richer in xylan than other raw materials as described in JP-B-56-50960, and the raw wood is naturally grown in large quantities in South America such as Brazil. Excellent stability.
However, from the viewpoint of manufacturing only xylose, the manufacturing method of the patent described above requires a complicated process and is not always advantageous in terms of cost.

In view of the above, an object of the present invention is to produce a high-purity xylose industrially at low cost and easily by using a nucleus layer of babas palm shell as a raw material.

The term "babas palm" as used in the present invention is classified as a palm plant and has names such as "Babassupalm" and "Orbignya martiana Barb-Rodr". The nuclear layer refers to a part called Endcarpo which encloses its seed.

[Means for Solving the Problems] In the present invention, a core layer of babas palm shell excellent in raw material supply properties is used, and the hydrolysis conditions are 0.1 to 3.0.
It is boiled under normal pressure or pressure at 100 130 ° C, preferably around 120 ° C, using N mineral acid. This allows glucose,
Production of arabinose and oligosaccharides can be suppressed, and xylose of high purity can be produced.

Further, with respect to the core layer of the babas palm shell as a raw material, after the pretreatment step of adding water or a dilute acid of 0.1 N or less and boiling to remove impurities dissolved in the solution, and performing the above hydrolysis, a higher purity is obtained. Xylose was obtained.

Separation and purification of xylose from the obtained hydrolyzate can be achieved by activated carbon treatment, ion exchange resin treatment, crystallization and the like.

 Hereinafter, specific examples will be described.

[Experimental Example 1] Production of xylose-containing liquid by sulfuric acid treatment (1) The core layer of the babassu shell was taken out and pulverized to a particle size of about 0.5 to 2.0 mm with a Willey mill to obtain a powder. 8.00 g (10 series) of this powder (dry matter) was used as a sample in a stoppered Erlenmeyer flask from 0 to 50% (v / v) (about 0 to 18%).
N) was added to 100 ml of sulfuric acid, and xylose was eluted in an autoclave at 120 ° C. under a pressure of 1 atm for 60 minutes. Table 1 shows the acid concentration of each series.

After the heat treatment, the hydrolyzate is filtered through glass fiber filter paper,
Separated into solid and filtrate. The solid was washed with water until the washing liquid became neutral, then dried at 105 ° C. for 5 hours and weighed. The filtrate was neutralized to pH 6.5 6.9 with barium hydroxide, the resulting barium sulfate was removed by filtration, the filtrate was concentrated, lyophilized, and weighed. Table 2 shows the mass balance of the eluate and the solid matter of the babasic husk nucleus powder at various sulfuric acid concentrations. The yield of the eluate relative to the raw material was as follows:
The most efficient results were obtained with a percentage (v / v) of more than 40%.

As a result of developing on a silica gel TLC plate (MERCK Art, 5554) to examine the sugar composition of the eluate, it was surprisingly treated with an experimental system CE (sulfuric acid concentration of 0.5 to 2.0% (v / v)). It was found that only xylose was produced (Fig. 1), and that experimental systems OB (sulfuric acid concentration 0)
In ~ 0.2% (v / v), arabinose and other contaminants derived from other hemicellulose contained in the nucleus layer of the babassu coconut shell are high, and in experimental systems FI (sulfuric acid concentration of 5.0 to 50.0% (v / v), With the production of cellulose-derived glucose,
It was shown that high purity xylose could be obtained only at the sulfuric acid concentration during this period.

Next, the total sugar content of each eluate was determined by the orcinol-sulfuric acid method and the amount of reducing sugar was determined by the Nelson-Somogi method, and the results are shown in Table 3. The ratio of the total sugar amount is experimental system AF (sulfuric acid concentration 0.1-5.0%
(V / v)), a value of about 60% was obtained, and the amount of reducing sugar was about 55% in the experimental systems CF (sulfuric acid concentration: 0.5 to 5.0% (v / v)). When the degree of polymerization of the sugar contained in the eluate is converted by the value of the total sugar amount / reducing sugar amount, the experimental systems C to G (sulfuric acid concentration
It is almost 1 at 1.0 to 10.0% (v / v), indicating that almost all of the eluted sugars have been decomposed into monosaccharides. In addition, it has been clarified here that in the experimental systems H and I (sulfuric acid concentration: 20.0 to 50.0% (v / v)), the sugar overdecomposition reaction is progressing.

The yield of sugar relative to the raw material in the eluate was 23% or more in the experimental systems DF (sulfuric acid concentration: 1.0 to 5.0% (v / v)) (fourth).
table).

As described above, the experimental systems D and E (sulfuric acid concentration 1.0, 2.0% (v / v)) were obtained in consideration of all the experimental results of the sugar content of the eluate relative to the raw material yield, xylose purity, sugar content, and degree of hydrolysis. It was clarified that the eluate obtained by the treatment did not contain contaminants and that xylose could be obtained in high yield.

[Experimental example 2] Purification of xylose syrup The lyophilized material of the filtrate part of the experimental systems D and E of Experimental example 1 (hereinafter, the lyophilized material of the filtrate part of each system is also simply referred to as eluate) and 10 ml of water. And 50 mg of coconut shell activated carbon (Wako Pure Chemical Industries, Ltd.) was added, followed by treatment at 40 ° C. for 60 minutes. The activated carbon was removed by filtration, and the treatment liquid was adjusted to 10 ml. This 5.00 ml was passed through a column of 1 to 1.5 ml of a strongly acidic ion exchange resin GC120 (H ⁺ ) type and 1 to 1.5 ml of a strongly basic ion exchange resin IR410 (OH ⁻ ) type for purification.

The syrup at each purification stage was assayed for sugar purity by the orcinol-sulfuric acid method.
It was 90.2% (Table 5), and the sugar composition was examined by HPLC. As a result, only the xylose peak was detected.

The results are shown in FIG. HPLC conditions were as follows: mobile phase: acetonitrile: water = 80:20 flow rate: 0.5 ml / min column: TOSOH Amide 80 (4.6 mm ID x 25 cm) temperature: 80 ° C detector: TOSOH RI-812 instrument: TOSOH SC- 8010 Sample injection volume: 20 μl (acetonitrile: sample aqueous solution = 80:20) Table 4 shows the yield of raw materials for sugars in each purification step. The yield of raw material xylose was about 21%.

[Experimental example 3] Production of xylose-containing liquid including pretreatment (2) Bavasu palm core layer powder (dry matter) 8.00 g (3 series O-2, A-2, B-2) was used as a sample, and a triangle with a stopper was used. Add 100 ml of water or dilute sulfuric acid solution of 0-0.2% (v / v) (approximately 0-0.072N) in the flask, pretreat in an autoclave at 120 ° C and 1 atm for 60 minutes, and remove the eluate by filtration 4.00 g (in terms of dry matter) of the solid obtained in this manner was used as a raw material for producing the following xylose-containing liquid. The sulfuric acid concentration in the pretreatment of each experimental system is in accordance with the experimental system having the same alphabetical symbol shown in Table 1. That is, in the O-2 experimental system, water was used and A-
0.1% dilute sulfuric acid was used in the two experimental systems and 0.2% in the B-2 experimental system.

4.00 g of solids treated under each pretreatment condition (dry matter equivalent)
Was added to 50 ml of 1% (v / v) sulfuric acid in a stoppered Erlenmeyer flask, and xylose was eluted in an autoclave at 120 ° C., 1 atmosphere of pressure and 60 minutes. Table 6 shows the results of determining the material balance of the eluate and the solid.

The sugar composition of the eluate was examined by TLC, and it was shown that only xylose was produced (FIG. 3).

As a result of measuring the total sugar amount and the reducing sugar amount in the same manner as in Experimental Example 1, the ratio of the total sugar amount was as shown in Table 7 in the experimental system O-2,
It was around 80% in A-2, which was improved by about 20% as compared with the experimental systems A to F obtained without the pretreatment obtained in Experimental Example 1. At the sulfuric acid concentration (0.2% (v / v)) during the pretreatment of the experimental system B-2, loss of xylose in the pretreatment stage was large, and no improvement in purity was observed.

This result indicates that the pretreatment has the effect of reducing the consumption of the activated carbon and the ion exchange resin used for the subsequent purification, and the value of the total sugar amount / reducing sugar amount is almost 1 in the pretreatment under appropriate conditions. Which indicates that almost all of the produced sugar is a monosaccharide.

As shown in Table 4, the sugar content relative to the raw material yield was as follows:
2 is the highest at about 24%, and it is clear that the pretreatment using water or sulfuric acid of about 0.1% (v / v) is better.

[Experimental example 4] Production of xylose (3) Scale-up of production of xylose was attempted based on the experimental examples so far. Tap water was added to 300.0 g (in terms of dry matter) of the powder to make the total amount 1500 ml, and the mixture was treated in a 2 L polypropylene container at 120 ° C. under pressure (gauge pressure 1 atm) for 60 minutes.
Filtration gave 289.8 g (in terms of dry matter) of a residue, to which 1% (v / v) sulfuric acid (about 0.36 N) was added to make a total volume of 1500 ml, and similarly treated at 120 ° C. for 60 minutes under pressure. The residue was removed by filtration, slaked lime was added to the filtrate to neutralize, and the generated calcium sulfate was removed by filtration. The filtrate was concentrated, and the precipitate was again removed by filtration. The resulting product was treated with activated carbon and an ion-exchange resin according to the method described in Experimental Example 2 to obtain a syrup.
Was used to analyze the sugar composition. The results are shown in FIG. The remaining syrup is concentrated and dried to 81.4 g of solids with 91.2% sugar purity
I got Calculated yield of sugar relative to raw material was 24.7%.

[Effects of the Invention] Conventionally, when xylose is produced from plant raw materials, generation of contaminating saccharides and generation of acetic acid due to high-temperature treatment (130 ° C. or higher) have been regarded as problems. The present inventors have found that the by-product of acetic acid
It was found that high-purity xylose can be produced by setting the temperature to as low as ℃ and avoiding it, and by using only the sulfuric acid treatment conditions using the banana palm shell core layer as the raw material. Bavasu palm grows abundantly in South America. In particular, the nuclear layer accounts for as much as 58% of it, but it is poorly used and is an unused resource with excellent supply stability as a raw material. In addition, the simplicity of the process of the present method allows high-purity xylose to be produced at low cost, and is extremely useful industrially.

[Brief description of the drawings]

FIG. 1 shows the sugar composition by TLC of the eluate obtained by treating the nucleus layer of baba coconut shell with sulfuric acid at various concentrations. FIGS. 2 (A), (B) and (C) show the sugar composition by HPLC of purified products of xylose standard samples and experimental systems D and E using activated carbon / ion exchange resin. FIG. 3 shows the sugar composition by TLC of the eluate obtained by 1% (v / v) sulfuric acid treatment after pretreatment. FIGS. 4 (A) and 4 (B) show the sugar composition of the standard sample of xylose and the syrup obtained by the method of Experimental Example 4 by HPLC.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C13K 13/00 101

Claims (2)

(57) [Claims] (1) The core layer of the babasi palm is prepared by adding 0.1 to 3.0N mineral acid in mineral acid.
A liquid phase is obtained by treating at 130 ° C. under normal pressure or under pressure.
A method for producing high-purity xylose, comprising separating and purifying xylose contained in the liquid phase. 2. The method according to claim 1, wherein the core layer of the babasi coconut shell has been subjected to a pretreatment for separating impurities dissolved in water or a dilute acid solution of 0.1 N or less. the method of.