JP5747488B2 - Woody pitch - Google Patents

Description

  The present invention relates to a technique for using a solid wood material containing cellulose, hemicellulose, lignin, lignocellulose and the like, and more particularly to a solubilization technique for the solid wood material.

  In recent years, fossil fuels have been promoted from the viewpoint of improving the global environment. For example, carbon materials (carbon fiber, activated carbon, carbon black, various functional carbon materials, etc.) are conventionally manufactured from distillation residues (such as pitch) of coal and petroleum, but solubilize wood-based materials, Attempts have been made to use it as a pitch substitute. For example, a method for producing carbon fiber using a solubilized wood-based raw material is known (Patent Documents 1 to 4 and the like). In Patent Document 1, a wood-based resource is treated with a high-pressure saturated steam treatment, an alcohol-based organic material. Carbon fiber is produced by hydrocracking lignin obtained by solvent treatment, spinning by hot melting method, and carbonizing. However, the method using hydrocracking is not desirable because of the high energy consumption.

  In Patent Document 2, by heating a woody material using a mixed solvent of phenols and water as a cooking solution, pulp, an aqueous layer in which hemicellulose is decomposed and dissolved as a monosaccharide, and lignin are dissolved. After separating into three components of the organic layer, lignin obtained by concentrating the organic layer under reduced pressure is melt-spun to produce lignin fibers. However, this method is not practical because the separation and refining operation of the pulp is complicated and it is difficult to treat the waste liquid in the aqueous layer portion.

  In Patent Document 3, a lignin for carbon fiber spinning is prepared by heat-healing a phenolized lignin obtained by treating a lignin eluted by delignification treatment from a woody material with an acidic organic catalyst in a non-oxidizing atmosphere. ing. However, this method is costly because the production process is complicated and the yield of carbon fibers is low.

  In Patent Document 4, a lignocellulosic material is pretreated for explosion, and a solubilized product is produced by dissolving the treated product and a phenol compound under heating. However, in this method, the explosion treatment apparatus is enormous and solid content remains in the product. Therefore, spinning is difficult and it is not suitable as a raw material for carbon fiber.

  In addition to carbon fiber, the wood-based raw material is expected to be used as a raw material for producing other carbon materials (activated carbon, carbon black, various functional carbon materials, etc.) (pitch or heavy oil). In any case, it is important to solubilize the wood-based raw material at low cost. When used as a carbon fiber production raw material, troubles occur in the spinning process if the solid content remains. In addition, when producing activated carbon, carbon black, various functional carbon materials, etc., if the solid content remains, process troubles occur due to clogging of the liquid feeding pipe and valve.

  In addition, in the above-mentioned conventional methods, the thermal stability of the product (solubilized product or pitch) is low except for the hydrocracking method (Patent Document 1) that requires high temperature, high pressure and high energy consumption. have. Especially for the pitch, thermal stability is important in its use, but with a pitch with low thermal stability, for example, it is impossible to obtain a desired fiber diameter due to an increase in the viscosity of the pitch during melt spinning (an increase in the softening point), Alternatively, the spinning itself cannot be performed due to the clogging of the nozzle. In addition, when the pitch is used as a carbon material molding binder, the pitch viscosity increases in the process of kneading with the aggregate, which makes it impossible to perform desired molding.

Japanese Unexamined Patent Publication No. Sho 62-110922 Japanese Patent Laid-Open No. 01-239114 Japanese Patent Laid-Open No. 01-306618 Japanese Patent Laid-Open No. 04-126725

  The present invention has been made paying attention to the circumstances as described above, and its purpose is to enhance the solubility (solubility) of solid woody materials containing cellulose, hemicellulose, lignin, lignocellulose, etc., and solubilize It is to establish a technique capable of enhancing the thermal stability of a woody pitch after removing low-boiling components from the product or its solubilized product.

  As a result of intensive studies to solve the above problems, the present inventors have solubilized a solid woody material containing at least one selected from cellulose, hemicellulose, lignin, and lignocellulose with a phenol compound. In addition, if a predetermined solvent is used in combination, it is found that insoluble matter (solid content) can be remarkably reduced, and thermal alteration of the woody pitch after removing low-boiling components from the solubilized product or solubilized product can be suppressed. The present invention has been completed.

  That is, the wood-based solubilized product according to the present invention comprises a solid wood-based raw material containing at least one selected from cellulose, hemicellulose, lignin, and lignocellulose. ) In the presence of pressure). The wood-based raw material is preferably obtained by biologically, chemically, or mechanically degrading a wood body, for example, after producing a ethanol by treating the wood body in the order of hydrothermal treatment, saccharification treatment, and fermentation. Of the residue. The amount of the phenols is 20 to 500 parts by mass with respect to 100 parts by mass of the wooden raw material. The amount of the hydrogen donating solvent is 10 to 300 parts by mass with respect to 100 parts by mass of the wood-based raw material. In the pressurization and heating, for example, a gauge pressure of 0.2 to 10 MPa and a temperature of 230 to 430 ° C. are used. After the heating under pressure, the solubilized product obtained may be used as a basic raw material for the carbon material as it is, or a low-boiling component in the solvent and the solubilized product is removed by distillation and used as a basic raw material for the carbon material. Also good.

  According to the present invention, since the solid woody material is heated under pressure in the presence of phenols and a hydrogen donating solvent, insoluble matter (solid content) can be remarkably reduced, and further, the solubilized product or the solubilized product thereof can be obtained. By suppressing the thermal alteration of the woody pitch after removing low boiling point components from the above, the thermal stability of these woody solubilized products or pitches, which are the basic raw materials of various carbon materials, including carbon fiber, is improved by conventional methods. Compared to the above, it can improve significantly and contribute to the stable production of products.

  In the present invention, a wood-based solubilized product or a wood-based pitch is prepared by pressurizing and heating a solid wood-based raw material in the presence of a predetermined solvent described later. By using a solid woody material, the dependence of fossil materials can be reduced. Moreover, by heating under pressure in the presence of a predetermined solvent, the solid woody material can be solubilized or pitched, the solid content can be significantly reduced, and a thermally stable solubilizate or pitch can be obtained. Can do.

  The solid wood material is not particularly limited as long as it is a solid material containing at least one selected from cellulose, hemicellulose, lignin, and lignocellulose, and any material derived from plants (particularly wood) can be used. It is. For example, wood-based waste materials such as thinned wood covering conifers and broad-leaved trees, forest land residual materials, lumber residual materials, construction waste materials, pruned branches, stumps and bark are desirable as solid wood-based raw materials from the viewpoint of effective use of waste.

  The solid woody material is preferably decomposed biologically, chemically or mechanically. By decomposing in advance, the processing efficiency of solubilization by pressure heating can be increased. Biological degradation includes degradation by fungi, microorganisms, enzymes, and the like. The chemical decomposition may be a sulfuric acid / alkali method, but hydrothermal treatment or hydrolysis with superheated steam is preferable in consideration of environmental load. In addition, the mechanical decomposition includes beating, crushing, crushing, grinding, and explosion, and this mechanical decomposition may be either dry or wet.

  These biological, chemical, or mechanical degradations are desirably combined as appropriate. Typically, after mechanical degradation (such as pulverization), hydrothermal treatment (hydrolysis treatment) is performed as necessary, and then biological degradation is performed. Scientifically, saccharification treatment (eg, saccharification treatment by enzymatic method) is performed. The saccharified product is usually separated into a liquid component and a solid content by filtration. The liquid component (main component is sugar) is subjected to ethanol fermentation, and the solid is discharged as a residue (saccharification residue). In some cases, the saccharified product may be sent to the subsequent stage without filtration and subjected to ethanol fermentation with microorganisms or fungi (particularly yeast). In this fermentation treatment, usually only the sugar content in the saccharification product is converted to ethanol, and the solid content (saccharification residue) does not change. The fermented product is also separated by filtration into a liquid component (main component is an aqueous ethanol solution) and a solid content (which is basically the same component as the saccharification residue, but here referred to as “fermentation residue”). The saccharification residue or fermentation residue thus obtained is mainly composed of lignin, and even if it contains cellulose and hemicellulose, it can be used as it is as a solid woody material. A preferable solid woody material is a saccharification residue or a fermentation residue. Details of these hydrothermal treatment, saccharification treatment, and fermentation treatment are described in detail in, for example, JP-A-2005-168335.

  In the present invention, the solid woody material as described above is solubilized by heating under pressure in the presence of a predetermined solvent. Specifically, the predetermined solvent is a combined solvent of phenols and a hydrogen donating solvent. If a solid woody material is dissolved in phenol under pressure and heating, a solid content (insoluble matter) is generated. This solid is assumed to be a recombination of unstable radicals generated by thermal decomposition, and if a hydrogen-donating solvent is used with phenols, the radicals are stabilized by donating hydrogen to unstable radicals. Therefore, it is considered that the solid content can be significantly reduced.

  Furthermore, the woody pitch after removing the low boiling point component is thermally altered in the spinning temperature region. That is, the softening point of the woody pitch becomes high and spinning becomes difficult. The increase in the softening point is thought to be due to the thermal polymerization of components with a thermally unstable phenolic skeleton in the wooden pitch. If used together with a hydrogen-donating solvent and phenols, it is presumed that oxygen is extracted from the unstable phenol skeleton that is the starting point of thermal polymerization, and thermal alteration of the resulting woody pitch is suppressed.

  The phenols mean compounds having a phenol skeleton (hydroxybenzene skeleton), and include, for example, monohydroxybenzenes such as phenol and cresol; dihydroxybenzenes such as catechol; and hydroxybenzene condensed rings such as naphthol. . Preferred phenols are monohydroxybenzenes, especially phenol.

  As the hydrogen-donating solvent, compounds obtained by partially hydrogenating condensed aromatic hydrocarbons can be used. For example, bicyclic compounds such as partially hydrogenated naphthalenes (tetralin, etc.); partial hydrogenation Tricyclic compounds such as anthracenes (such as 9,10-dihydroanthracene), partially hydrogenated phenanthrenes (such as 9,10-dihydrophenanthrene), and tetracyclic compounds such as partially hydrogenated fluoranthene (such as tetrahydrofluoranthene) Etc. are included. As the hydrogen-donating solvent, a hydrogenated mixture containing a condensed aromatic hydrocarbon such as anthracene oil or creosote oil can also be used. A preferred hydrogen donating solvent is a low boiling point solvent containing the bicyclic compound, particularly a solvent containing partially hydrogenated naphthalenes.

  The amount of phenols and hydrogen-donating solvent used is not particularly limited as long as it is sufficient to solubilize the solid woody material, but even if used in excess, there is no further effect, and productivity is reduced. Therefore, it is recommended to use an appropriate amount. When using a saccharification residue or fermentation residue as a solid woody material, the amount of phenol is, for example, about 20 to 500 parts by mass, preferably about 50 to 400 parts by mass, with respect to 100 parts by mass of the saccharification residue or fermentation residue. More preferably, it is about 100 to 300 parts by mass. When the amount of phenols is less than 20 parts by mass, the solubility in solid raw materials is remarkably reduced, and when the amount of phenols exceeds 500 parts by mass, the amount of phenols necessary for dissolution is sufficient, but the solvent Energy consumption required for recovery increases, leading to cost increase. The amount of the hydrogen donating solvent is, for example, about 10 to 300 parts by mass, preferably about 30 to 250 parts by mass, and more preferably about 50 to 200 parts by mass with respect to 100 parts by mass of the saccharification residue or fermentation residue. . When the amount of the hydrogen donating solvent is less than 10 parts by mass, the solubilized product and the pitch are likely to be thermally altered, resulting in an increase in solid content and a decrease in thermal stability. On the other hand, when the amount of the hydrogen donating solvent exceeds 300 parts by mass, as in the case of the phenol, the energy consumption required for solvent recovery increases, leading to an increase in cost.

  When the solid wood-based raw material is solubilized by heating under pressure in the presence of the solvent, the heating temperature is about 230 to 430 ° C, preferably about 260 to 400 ° C, more preferably about 280 to 380 ° C. If the temperature is below 230 ° C., the solubilization is insufficient, so the amount of solids increases, and if it exceeds 430 ° C., the cyclization polycondensation reaction is promoted and the solid content as a carbon precursor increases. The gauge pressure is about 0.2 to 10 MPa. This gauge pressure is determined by the vapor pressure at a predetermined temperature of moisture in the raw material, low-boiling components generated by thermal decomposition, phenols to be used, and hydrogen donating solvent. The treatment time at the above pressure and temperature (holding time after reaching a predetermined temperature) is, for example, about 1 to 120 minutes, preferably about 5 to 60 minutes, and more preferably about 10 to 30 minutes.

  After the solid woody material is solubilized as described above, the solubilized product may be used as it is as a raw material for a binder or carbon black. If necessary, the solubilized product is concentrated to binder pitch and carbon. You may make it the pitch for fibers, various molded articles, etc. Concentration operations consist of the moisture contained in the solid wood material, the solvent used for solubilization (phenols, hydrogen-donating solvent, etc.), and the low-boiling decomposition products (pyrolysis oil and pyrolysis produced during pressure heat treatment) (Water generated by the above) (these are collectively referred to as low boiling point components) can be removed, and may be carried out under reduced pressure conditions or under normal pressure conditions.

  The amount of solid content remaining in the solubilized product can be measured by a method of filtering before the concentration operation. That is, after solid woody material is pressurized and heated in a predetermined solvent, the content is filtered through a paper filter (retained particle diameter of about 1 to 10 μm), so that the solid content can be separated and the amount can be examined. . The solid content contained in the solubilized product before filtration is, for example, 5% by mass or less, preferably 4% by mass or less, and more preferably 3% by mass or less, with respect to the input solid woody material (105 ° C. dry base). It is. If the amount of these solids is small, the solubilized product may be used as the basic raw material of the carbon material as it is without filtering, but if necessary, for example, when finely processing such as carbon fiber It may be removed by filtration.

  When the wood-based solubilized product is concentrated to a wood-based pitch, the softening point can be controlled by the degree of concentration. The softening point of the raw material pitch of the carbon fiber for melt spinning is usually about 170 to 230 ° C.

Further, the thermal stability index of the woody pitch is held here at 285 ° C. for 60 minutes with respect to the pitch whose softening point is adjusted within the range of 190 to 210 ° C. by concentration under reduced pressure at 280 ° C. (heat treatment). The difference between the softening points before and after, that is, ΔT (° C.) = T ₂ (° C.) − T ₁ (° C.) is defined. Here, T ₁ is the softening point before holding at 285 ° C. for 60 minutes, and T ₂ is the softening point after holding at 285 ° C. for 60 minutes. This ΔT is preferably 15 ° C. or less, more preferably 10 ° C. or less.

  Examples of the carbon material that can be produced from the above wood pitch or wood solubilized material include carbon fiber, molded activated carbon, carbon black and the like. Carbon fiber, for example, melts and spins a wooden pitch, heats it in air (about 200 to 300 ° C.) to make it infusible, and heats it in a non-oxidizing atmosphere (about 700 to 900 ° C.). Can be produced by carbonization. Molded activated carbon, for example, kneads wood pitch with charcoal powder, molds, carbonizes in a non-oxidizing atmosphere, and then activates it in an oxidizing atmosphere such as steam or carbon dioxide (about 800 to 1000 ° C.). Can be manufactured. For example, in the furnace method, carbon black can be produced by continuously spraying and thermally decomposing droplets of a wood-based solubilizate from a nozzle in a high-temperature gas atmosphere of about 1300 to 1700 ° C.

  In the production process of carbon materials (carbon fiber, molded activated carbon, carbon black, various carbon molded products, etc.), if the above wood pitch or wood solubilized product is used, the solid content is remarkably reduced and the thermal stability is remarkable. As a result, there is no risk of pipes, valves, nozzles, etc. being blocked at the time of shipping, or incapability of operation due to increased viscosity (e.g., increased softening point) during molding, allowing stable production to continue. .

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

Reference example 1
After crushing unused woody biomass of about 5-100 cm in diameter consisting of cedar stumps and branches and leaves into chips of 3-5 cm square using a crusher, it was naturally dried until the water content was about 20% by mass. Further, the powder was pulverized into a powder having an average particle size of about 20 μm and a water content of about 3% by mass. To 100 parts by mass of this wood flour, 5 parts by mass of Acremonium cellulase (Meiji Seika, trade name: Acremonium Enzyme) and 500 parts by mass of water are added, and saccharification treatment is carried out at a temperature of 55 ° C. for 40 hours (the saccharification rate is in the raw material) And 35% by mass with respect to 100% by mass of cellulose), followed by filtration to separate into liquid component (a) and solid content. The solid content was further washed with water, and the washing liquid (b) and the liquid component (a) were combined and subjected to ethanol fermentation. The solid content (residue of saccharification treatment) was naturally dried and then crushed into a powder form, and further dried overnight at a temperature of 105 ° C. to obtain a saccharification residue as a raw material for the wood-based solubilized product and wood-based pitch. The yield of the saccharification residue was 82% by mass with respect to 100% by mass of the dry mass of the raw material wood flour.

Example 1
To 50 g of cedar saccharification residue obtained in Reference Example 1, 75 g of phenol and 75 g of tetralin were added and heated at 350 ° C. for 1 hour under a gauge pressure of 7 MPa. The solid content in the obtained heat treatment liquid was 2.9% by mass with respect to the charged saccharification residue raw material (105 ° C. dry base). After removing the solid content in the heat treatment liquid with a paper filter, the obtained filtrate (solubilized product) was concentrated under reduced pressure at 280 ° C. to obtain a woody pitch. The resulting woody pitch had a softening point [T ₁ ] of 190 ° C. Further, the softening point [T ₂ ] after holding this woody pitch at 285 ° C. for 60 minutes (heat treatment) was 194 ° C. and ΔT = 4 ° C.

Example 2
To 50 g of the cedar saccharification residue obtained in Reference Example 1, 75 g of phenol and 75 g of tetralin were added and heated at 375 ° C. for 1 hour under a gauge pressure of 7.5 MPa. The solid content in the obtained heat treatment liquid was 2.1% by mass with respect to the charged saccharification residue raw material (105 ° C. dry base).

Comparative Example 1
To 50 g of cedar saccharification residue obtained in Reference Example 1, 150 g of phenol was added, and a heat treatment was carried out at 350 ° C. for 1 hour under a gauge pressure of 7 MPa. The solid content in the obtained heat treatment liquid was 8.5% by mass with respect to the charged saccharification residue raw material (105 ° C. dry base). This solubilized product was filtered and concentrated in the same manner as in Example 1 to obtain a woody pitch (softening point [T ₁ ] 210 ° C.). Further, the softening point [T ₂ ] after holding (heat treatment) this woody pitch at 285 ° C. for 60 minutes was 235 ° C., and ΔT = 25 ° C., as in Example 1.

Comparative Example 2
To 50 g of the cedar saccharification residue obtained in Reference Example 1, 150 g of phenol was added, and a heat treatment was performed at 375 ° C. for 1 hour under the condition of a gauge pressure of 7.4 MPa. The solid content in the obtained heat treatment liquid was 12.1% by mass relative to the charged saccharification residue raw material (105 ° C. dry base).

Claims (3)

The residue after saccharification treatment of the wood body or the residue after saccharification and fermentation treatment of the wood body is obtained by heating under pressure in the presence of phenols and a hydrogen donating solvent to remove low-boiling components. A woody pitch with a softening point of 170-230 ° C. The woody pitch according to claim 1, wherein the residue is obtained by biologically, chemically, or mechanically degrading a woody body. The woody pitch according to claim 1 or 2 , wherein the phenol is phenol and the hydrogen-donating solvent is tetralin.