JP2001089986A - Method of manufacturing for pulp using aqueous solvent of high-boiling organic solvent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of solvent pulping enabling the recycling of a high-boiling organic solvent to a pulping process or the like in which an operation for separating and recovering the high boiling organic solvent is omitted. SOLUTION: This method for producing various pulps for paper making, cellulose derivative production or saccharification comprises the following processes: a pulping process in which a known pulp raw material such as a woody material or agricultural wastes, and an aqueous solvent containing 50-90% a high-boiling organic solvent (referred to as HBS) having a boiling point of 150-250 deg.C and soluble in water are filled in a pressure-resistant container at a liquid ratio of 4-10, and they are treated at 180-230 deg.C; a process for separating waste liquid from the pulp; a process for washing the separated pulp (crude pulp) with the high-boiling organic solvent and boiling water; a process for separating the washed pulp; a process in which lignin is precipitated from the above waste liquid and the washing liquid of the washing process by adding dilution water and the precipitated lignin is recovered by filtration; and a process in which a specified amount of water is removed by distillation from the filtrate to recover a solvent containing 70-80% the high-boiling organic solvent, the recovered solvent is recycled at least to the pulping process, and the hot water generated by the distillation of water is recycled to the crude pulp washing process as the boiling water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a paper biomass (including agricultural waste) containing various pulp raw materials for papermaking and a cellulose derivative using a solvent system containing a water-soluble high-boiling organic solvent as a main component. The present invention relates to a method for producing pulp for energy saving in a method for producing various pulp for saccharification (solvent pulping method), in which the circulation use of a high boiling point organic solvent is devised.

[0002]

2. Description of the Related Art A method for treating pulp raw materials such as wood with a water-soluble organic solvent to separate lignin, hemicellulose, sugar and cellulose components of the pulp raw material is known (for example, US Pat. No. 3,585,104). And the fourth
No. 100016), in particular, a pulp production method using a high-boiling organic solvent is also known (for example, literature using a high-boiling point: Johanson et. Al .: Pap. Puu. 69 (1987), (6), 500).
-504. Pulping with THFA-HCl. Grondal, BL et. A
l.: USpat. 2,7772,968 (1950): Pulping with triethiene glycol-AlCl3. Nelson: Appita 3 (11) 29
(1977): Pulping with ethylene glycol-salicylic acid. Schweers: Chemtech 132 (8) 490 (1974): Pulping with phenol. Sano et.al .: Japan Tappi, 42 (198
8) (5), 487-496: Pulping with cresol. Sano and
Uraki: Holzforshung, 53 (1999) 411-415 .: Normal pressure pulping with polyhydric alcohol-HCl. reference). Such solvent pulping is an attractive alternative to conventional chemical pulping, such as kraft pulping and sulfite pulping, which suffer from relatively high equipment costs and pollution. In the method described in the above-mentioned U.S. Pat. No. 4100016, a method of diluting with water is employed for recovering lignin from an organic solvent / water-black liquor, but it is not efficient. Therefore, a dilution method using water to which an acid has been added has been proposed as an improvement method, but the use of a solvent is inconvenient because the acid is added.

In the pulp production method using the high boiling point organic solvent, the used high boiling point organic solvent is separated and recovered, which is not a preferable method in that the recovery requires a lot of energy.

[0004]

SUMMARY OF THE INVENTION The present inventor has omitted the operation of separating and recovering a high-boiling organic solvent to be used, and separating and recovering lignin, which is a main component of waste liquid and the like. After, the high boiling organic solvent,
If a solvent pulping method that can be reused in a pulping step or the like while containing other components can be designed, the problem of consuming a large amount of energy for recovering an organic solvent can be reduced while taking advantage of the solvent pulping method. SUMMARY OF THE INVENTION An object of the present invention is to realize a solvent pulping method as described above, considering that the above-described pulping method can be realized. In order to solve the above problems, high-boiling organic solvents and waste liquid used,
While examining a pulping method that combines the recovery of lignin from crude pulp washings and the efficient reuse of high-boiling organic solvents, without isolating and recovering high-boiling organic solvents, The present inventors have found a method of adjusting the content to a high boiling point organic solvent concentration used in a pulping step or the like, and recovering and reusing the same, thereby solving the above-mentioned problem. In the precipitation / recovery of lignin, the discovery that the total amount of the water washing solution and water added to the waste liquid is 2-3 times the volume can substantially recover lignin in the waste liquid, etc. It is an important factor. HB by a solvent containing a saccharide, for example, a monosaccharide such as mannose or glucose;
Even in S pulping, the pulping yield is slightly reduced (under the same pulping temperature and pulping time).
However, the finding that the amount of residual lignin in the pulp is reduced and that the hydrogenation of mannose to mannitol shows the same pulping properties as using a fresh solvent is increasingly useful for the present invention. It supports sex.

[0005]

SUMMARY OF THE INVENTION A first aspect of the present invention is to provide a known pulp raw material such as wood material and agricultural waste, and a high boiling organic solvent (HBS) that is soluble in water having a boiling point of at least 150 to 250 ° C. A pulping step in which an aqueous solvent containing 50 to 90% is filled into a pressure-resistant reactor at a liquid ratio of 4 to 10 and treated at a temperature of 180 to 230 ° C, a step of separating waste liquid from pulp, separation Pulp (coarse pulp)
Washing the pulp with a high-boiling solvent and boiling water, separating the washed pulp, and diluting water from the waste liquid and the washing liquid from the washing step to precipitate lignin, and collect lignin by filtration. And removing a predetermined amount of water from the filtrate to recover a solvent containing 50 to 90% of a high-boiling organic solvent. The solvent is used at least in the pulping step. This is a method for producing various pulp for paper, cellulose derivative, and saccharification, including a step of using as boiling water in a washing step. Preferably, the method for producing the pulp is characterized in that the water-soluble high-boiling organic solvent is a polyhydric alcohol having 2 to 5 carbon atoms, or a cyclic ether substituted with a hydroxyalkyl group. Acetic acid up to 10% by volume.

[0006] The second aspect of the present invention is that in one reaction tower, a pulp raw material and an aqueous solvent containing a water-soluble high-boiling organic solvent are continuously supplied from above, and 180 pulps are provided in the pulping section at the front stage of the tower. ~ 2
Pulping at a temperature of 30 ° C., separating waste liquid from the pulp at the rear of the pulping unit, and containing the high-boiling organic solvent introduced from the rear of the solvent washing stage into the pulp (coarse pulp) entering the next solvent washing stage The solvent is used to carry out countercurrent heating by using the residual heat in the pulping step, and then the pulp transferred to the water washing stage is subjected to countercurrent heating washing with a water washing liquid introduced from the rear of the water washing stage (the latter stage of the reaction tower). Including the step of extracting the purified pulp after washing from the bottom of the tower, for paper, for cellulose derivatives,
In the continuous pulping method for manufacturing various pulps for saccharification, the separation of lignin from pulp waste liquor and washing liquid discharged from the solvent washing step as a solvent containing high boiling point organic solvent used in the pulping section and solvent washing section A continuous pulping method characterized by recovering and reusing the solvent recovered by distilling off a predetermined amount of water. Preferably,
Pulp waste liquor, lignin is precipitated and separated by adding dilution water to the crude pulp washing liquid, and water is distilled off from the remaining solution to prepare a solution of a recovered high-boiling organic solvent containing saccharides,
The continuous pulping method characterized in that the solution is repeatedly reused as a pulping solvent and a pulp washing solvent, and more preferably, a saccharide or a sugar modified product, a low-molecular compound contained in the recovered high-boiling organic solvent solution. The continuous pulping method according to the above method, characterized in that the lignin decomposition product is stabilized by hydrogenolysis or oxidative decomposition, and is used as a pulping solvent together with a high-boiling organic solvent.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail. A. Examples of high-boiling organic solvents soluble in water include: Hydroxyalkyl group-substituted cyclic ethers such as tetrahydrofurfuryl alcohol, butanediols, propanediols, ethylene glycol, glycerol, and polyhydric alcohols having 2 to 5 carbon atoms such as pentanediol can be mentioned. From the viewpoint of stability, tetrahydrofurfuryl alcohol, which can be prepared from 1,3- and 1,4-butanediol and wood, and 1,1,
5-pentanediol and the like can be cited as preferable water-soluble high-boiling organic solvents. 2. An aqueous solvent containing a high-boiling organic solvent soluble in water is defined as an aqueous solvent containing a high-boiling organic solvent soluble in fresh water (initial process), pulp waste liquor, and washing liquid discharged from the solvent washing process. A recovered aqueous solvent obtained by distilling lignin and a predetermined amount of water. 3. The present invention is characterized in that a high-boiling organic solvent is recovered and reused by separating and recovering lignin from a pulp waste liquid or a washing liquid discharged from a solvent washing step and distilling off a predetermined amount of water. . That is, saccharides and the like are still contained in the solvent to be reused.

B. About recovery and reuse of high boiling organic solvents. From experiments conducted by the present inventors to know the dilution water required for the recovery of lignin from pulp waste liquid and solvent washing liquid,
The total volume of water washing solution and water added to pulp waste liquid for precipitation and recovery of lignin is 2-3 times the volume (to HBS solvent)
Was found to be sufficient. Table 1 shows an experiment on the amount of dilution water required to isolate lignin dissolved in a high boiling point solvent. This finding is important data for the design of the pulping process by recovery and reuse of the high boiling organic solvent of the present invention.

[0009]

[Table 1]

This is of course applicable to the case where another high boiling point solvent is used.

C. About pulping (digestion) conditions. Here, a case where 1,4-butanediol (expressed as 1,4-BDOL) is used as a high-boiling-point solvent (which may be simply expressed as HBS) and fir pine is used as a pulp raw material will be described. Naturally, the present invention can be applied to the case where a high boiling point solvent and a pulp raw material are used. 1. FIG. 1 shows (addition amount of acetic acid 5%, pulping temperature 220
C., 1 hour), and the relationship between the HBS concentration and the pulping rate (sometimes referred to as pulp yield). Although it is necessary to consider the pulping rate, lignin yield and residual lignin (KL), it shows that the conditions can be selected in relation to the pulping rate and the recovered HBS. In the following drawings, each bar graph has the meaning displayed at the lower right of FIG. 2. FIG. 2 shows (acetic acid addition 10%, 70% 1,4-BDOL),
1 shows the relationship between pulping (pulping) temperature and pulping rate, lignin yield and residual lignin (KL). High temperature pulping is preferred in view of the residual lignin.

3. FIG. 3 shows the relationship between pulping time and pulping rate, lignin yield and residual lignin (KL) (10% acetic acid added, pulping temperature 220 ° C., 70% 1,4-BDOL). It is understood that a pulping time of one hour is sufficient. 4. FIG. 4 shows (70% 1,4-BDOL, pulping time 2 hours), the relationship between the amount of acetic acid added and the pulping rate, lignin yield and residual lignin (KL). This shows that the amount of residual lignin can be improved by adding acetic acid. The addition of acetic acid is suppressed as much as possible because it promotes the deterioration of high-boiling solvents, such as oxidation, in high-temperature pulping.

D. On the relationship between high boiling point solvents and pulping ratio, lignin yield and residual lignin (KL). In FIG. 5 (addition amount of acetic acid 5%, HBS concentration 70%, pulping temperature 220 ° C., 1 hour), 1,4-BDOL, 1,4
The relationship such as pulping ratio when 3-butanediol (1,3-BDOL) and tetrahydrofurfuryl alcohol (THFA) are used is shown. The high boiling point solvent mentioned in the present invention is pulp. It shows that it has almost the same characteristics with respect to the conversion.

[0014]

EXAMPLES Example 1 (batch conditions) Wood chips or non-wood chips are placed in an autoclave. 70-80% 1,3-butanediol is added so that the liquid ratio becomes 4-10. 200 to 60 to 90 minutes
The temperature is raised to 220 ° C. and kept at this temperature for 1 to 2 hours to pulping. Separate into crude pulp and waste liquid. To the separated crude pulp, 1,3-butanediol or 1,3-butanediol recovered from a waste liquid is added, and the operation of adding boiling water and washing at the temperature of boiling water is repeated twice. The waste liquor and the washing effluent are combined into a pulp waste liquor. The operation of further adding water to the crude pulp, heating to 60 to 80 ° C., and washing is repeated twice. The water wash was used as dilution water and added to the pulp waste liquor with stirring. If necessary, add a little more water to precipitate the lignin. The total amount (diluent) of the water washing liquid and water added to the pulp waste liquid is set to be two to three times the volume of the pulp waste liquid. The lignin is filtered off with suction, washed with a little hot water and separated. Water is distilled off from the filtrate under reduced pressure to obtain a 70-80% recovered 1,3-butanediol solution. This recovered 1,3-butanediol solution is used for the next batch pulping and crude pulp washings. The obtained pulp is dissociated by a disintegrator and selected by a flat screen, and then analyzed for pulp yield, residual lignin, viscosity and strength. These pulping and washing operations can be performed using a continuous reaction tower.

FIG. 6 shows the principle of continuous pulping. From the top of the reaction tower (RT), an aqueous solvent containing a pulp raw material (P) and a water-soluble high-boiling organic solvent (here, recovered HBS)
Solvent; HBS) is supplied continuously. The pulping is performed at a temperature of 180 to 230 ° C in the pulping section (P, S) at the front (upper) of the tower. The waste liquid is separated from the pulp at the rear of the pulping section, and the pulp waste liquid (BW) is extracted. The pulp (crude pulp) is transferred to a subsequent solvent washing stage. Heating countercurrent washing is carried out with a solvent containing a high-boiling organic solvent (here, a recovered HBS solvent; R.HBS) introduced from the back of the solvent washing stage (WS) by using the residual heat in the pulping step.
Then, the pulp transferred to the water washing stage (hot water washing unit; HW.W) is washed by heating countercurrent washing with a water washing liquid (e.g., distilled water) introduced from the rear part of the water washing stage (the latter stage of the reaction tower). Later purified pulp (HBS pulp) is withdrawn from the bottom of the column. On the other hand, the pulp waste liquid or the water washing liquid (WW) discharged from the pulp HBS solvent washing step separates (filters) and collects (LR) lignin therefrom, and removes a predetermined amount of water from the separated liquid. The HBS solvent is collected by distillation (reduced pressure distillation) and reused as an aqueous solvent for pulping and as a washing solvent in the solvent washing step, and the distilled water is recycled in the water washing step (hot water washing section).

Example 3 Birch was used as a pulp raw material, a fresh HBS solvent was used, and a recovered HBS was used (N
o. Table 2 shows the mass balance of the pulping of the second and third liquids (the first and second recovery liquids were used).

[0017]

[Table 2]

From these results, it can be seen that even when the HBS solvent obtained by the method for recovering a solvent according to the method of the present invention is used, sufficient pulping is performed.

The strength characteristics of the birch HBS pulp obtained under the conditions of Example 2 were examined. Table 3 shows the results.

[0020]

[Table 3]

Pulping No. Corresponds to Table 2. From this result, the pulp obtained by using the HBS solvent obtained by the method for recovering a solvent according to the method of the present invention was found to be fresh H
It turns out that it is not inferior to the pulp obtained using the BS solvent.

Example 3 Here, in the case where fir is used as a pulp raw material,
Table 4 shows the same results as in Example 2.

[0023]

[Table 4]

Pulping solvent: 70% 1,3-BDOL, liquid ratio:
6. The pulping conditions were the same as in Example 2, except that the pulping temperature was 220 ° C. and the cooking time was 1 hour. As a result, it can be seen that the same results as in Example 2 can be obtained even when the pulp raw material changes.

The strength characteristics of Abies sachalinensis HBS pulp obtained under the conditions of Example 3 were examined. Table 5 shows the results.

[0026]

[Table 5]

Pulping No. Corresponds to Table 4. From this result, the pulp obtained by using the HBS solvent obtained by the method for recovering a solvent according to the method of the present invention was found to be fresh H
It turns out that it is not inferior to the pulp obtained using the BS solvent.

Table 6 shows the material balance when various pulping raw materials are pulped using an HBS solvent. The pulping conditions here were: batch (100 ml autoclave), pulping solvent: 80% 1,3-BDOL, liquid ratio: 4-6,
Pulping temperature: 180-200 ° C, cooking time 1-3 hours.

[0029]

[Table 6]

When this result is compared with the pulping material balance of birch (see also the above Example 2), it is understood that the pulping characteristics are not significantly changed even when other pulp raw materials are used. It is understood that pulping using the recovered HBS solvent is applicable even when other pulp raw materials are used.

Here, the effects of monosaccharides, specifically mannose and glucose, in the HBS solvent on pulping of the HBS solvent, and the reduction of the saccharides in the HBS solvent,
The effect on solvent pulping was studied. Table 7 shows the results.

[0032]

[Table 7]

From this table, it can be seen that the pulping yield also slightly decreases in HBS pulping with a solvent containing a saccharide, for example, a monosaccharide such as mannose or glucose (under the same pulping temperature and pulping time). Although,
It is understood that the amount of residual lignin in the pulp decreases, and that when mannose is hydrogenated to mannitol, the same pulping characteristics as when a fresh solvent is used are exhibited. In addition, it has been confirmed that the same effect as the above-described hydrogenation treatment is also obtained when the saccharides or sugar altered products contained in the recovered high-boiling organic solvent solution are subjected to hydrogenolysis or oxidative decomposition of low-molecular-weight lignin decomposition products. I have.

[0034]

As described above, the circulation of the high-boiling organic solvent of the present invention is designed to separate lignin from the pulp waste liquid or the washing liquid discharged from the solvent washing section and to distill a predetermined amount of water from the washing liquid. It can be sufficiently reused as a solvent in the pulping step, which has an excellent effect of reducing the amount of water and energy used.

[Brief description of the drawings]

Fig. 1 Relationship between HBS concentration in softwood and pulping rate (sometimes referred to as pulp yield)

Fig. 2 Relationship between pulping (pulping) temperature and pulping rate, lignin yield and residual lignin (KL) of conifers

Fig. 3 Relationship between pulping time and pulping rate, lignin yield and residual lignin (KL) of conifers

Fig. 4 Relationship between amount of acetic acid added and pulping rate, lignin yield and residual lignin (KL)

FIG. 5 Relationship between pulping ratio and the like when 1,4-BDOL, 1,3-butanediol (1,3-BDOL), and tetrahydrofurfuryl alcohol (THFA) are used as high boiling point solvents

Fig. 6 Principle of continuous pulping

[Explanation of symbols]

R. T Reaction tower P Pulp raw material W. S solvent washing stage HBS recovered HBS solvent S Pulping unit HW. W Hot water washing unit PHBS pulp B. W Pulp waste liquid HBS pulp HBS washing solution W water washing solution L. R Lignin recovery

Claims (6)

[Claims] 1. A known pulp raw material such as wood material and agricultural waste, and a high boiling organic solvent (abbreviated as HBS) 50-9 soluble in water having at least a boiling point of 150-250 ° C.
An aqueous solvent containing 0% is filled in a pressure-resistant reactor at a liquid ratio of 4 to 10 and treated at a temperature of 180 to 230 ° C., a pulping step, a step of separating waste liquid from the pulp, and a separated pulp (coarse pulp) Washing with a high boiling point solvent and boiling water,
Separating the washed pulp, and, from the waste liquid and the washing liquid discharged from the washing step, adding dilution water to precipitate lignin, and collecting lignin by filtration,
A predetermined amount of water is distilled off from the filtrate to remove the high boiling organic solvent 50 to 9
Recovering a solvent containing 0% and using it in at least the pulping step, and using the hot water generated by the water distillation as boiling water in the crude pulp washing step.
A method for producing various pulps for paper, cellulose derivatives, and saccharification. 2. A water-soluble high-boiling organic solvent having 2 to 2 carbon atoms.
The method for producing pulp according to claim 1, wherein the polyhydric alcohol is a cyclic alkyl ether substituted with a hydroxyalkyl group. 3. The process for producing pulp according to claim 1, wherein the aqueous solvent contains up to 10% by volume of acetic acid. 4. In one reaction tower, an aqueous solvent containing a pulp raw material and a water-soluble high-boiling organic solvent is continuously supplied from above, and at a temperature of 180 to 230 ° C. in a pulping section at the front stage of the tower. Pulping, separating waste liquid from the pulp at the rear of the pulping section, and pulping the pulp (coarse pulp) entering the next solvent washing stage with a solvent containing a high-boiling organic solvent introduced from the rear of the solvent washing stage. The pulp transferred to the water-washing stage is heated and countercurrent-washed using the water washing liquid introduced from the rear of the water-washing stage (the rear stage of the reaction tower), and purified after washing. Pulp includes a step of extracting from the bottom of the tower, for paper, for cellulose derivatives, in a continuous pulping method for producing various pulp for saccharification, a solvent containing a high-boiling organic solvent used in the pulping unit and the solvent washing unit As the pulp A continuous pulping method characterized by separating and recovering lignin from waste liquid and a washing liquid discharged from a solvent washing step, distilling a predetermined amount of water, and reusing the recovered solvent. 5. A pulp waste liquid and a crude pulp washing liquid are added with dilution water to precipitate and separate lignin, and water is distilled off from the remaining solution to prepare a solution of a recovered high-boiling organic solvent containing saccharides. The continuous pulping method according to claim 4, wherein the solution is repeatedly reused as a pulping solvent and a pulp washing solvent. 6. A saccharide, a modified sugar, or a low molecular weight lignin decomposition product contained in the recovered high-boiling organic solvent solution is stabilized by hydrogenolysis or oxidative decomposition, and used as a pulping solvent together with the high-boiling organic solvent. The continuous pulping method according to claim 4 or 5, wherein: