CN115287931B

CN115287931B - Method for classifying long and short fibers of forest biomass and application of method

Info

Publication number: CN115287931B
Application number: CN202210602625.XA
Authority: CN
Inventors: 王岚; 李名路; 陈洪章
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2023-06-09
Anticipated expiration: 2042-05-30
Also published as: CN115287931A

Abstract

The invention relates to a method for classifying long and short fibers of forest biomass and application thereof. Based on the difference of the enzymolysis conversion performance of the wood biomass tissue cells, the method separates the long and short fibers and provides a method for reducing the enzyme consumption by the grading utilization of the wood biomass long and short fibers. The invention can effectively grade the raw material long and short fibers, improves the uniformity of enzymolysis substrates, improves the solid content, reduces the enzyme dosage, accelerates the liquefaction process and improves the enzymolysis efficiency, thereby achieving the purpose of improving the comprehensive utilization rate of forest biomass. The method utilizes the graded enzymolysis of the long and short fibers, reduces the enzyme consumption to improve the enzymolysis conversion economy of the forest biomass, has the advantages of simple process, high solid content, low consumption, low cost and high value co-production, and is easy for industrial production.

Description

Method for classifying long and short fibers of forest biomass and application of method

Technical Field

The invention belongs to the technical field of lignocellulose treatment, and relates to a method for classifying long and short fibers of forest biomass and application thereof.

Background

The forest biomass energy is used as an important renewable energy source, has the characteristics of large reserve, cleanness, reproducibility and the like, and is one of important renewable resources. Based on the association of the raw material structure, the process conversion and the product characteristics, the 'component selective resolution-functional economical utilization' is a necessary trend of the conversion and utilization of the forest biomass. The grading utilization of the forest biomass is an effective means and measure for improving the comprehensive utilization rate of the whole components. At present, related researches are carried out on the forest biomass for fractional conversion, but the technology is only remained on the macroscopic plant organ structure or chemical component level, and the technical research on fractional utilization of the microstructure of the forest biomass is not yet available.

CN113981726a discloses a method for fluffing and producing needle refined cellulose by using a biological method, which comprises crushing and soaking needle raw materials, increasing the flexibility of the needle raw materials, and attaching laccase as a biological treatment agent by combining a microporous sphere carrier made of clay, so that the enzymolysis efficiency and stability are ensured, the loss is avoided, the dispersed fineness of cellulose can be effectively improved, and the agglomeration is avoided. However, the raw materials of the method are limited to needle raw materials, and the microporous ball carrier is required to be manufactured to attach laccase as a biological treatment agent, so that the operation process is complex, the cost of fiber classification is greatly increased, and the method is not beneficial to industrialized popularization and application.

CN112251482a discloses a pretreatment method for grading utilization of traditional Chinese medicine residues and application thereof, which obviously reduces pretreatment time and energy consumption by the synergistic effect of trace organic acid and ionic liquid, and improves the performance and yield of products; the comprehensive fiber enriched product and lignin product are regenerated step by step, so that the whole utilization rate of the traditional Chinese medicine residues is remarkably improved. However, the raw materials of the method are only limited to the Chinese medicinal residues, and the synergistic effect of the trace organic acid and the ionic liquid only realizes the classification of chemical components, and the cell level classification of the fully-fibrous enrichment product is not performed, so that the improvement of the comprehensive utilization rate of the whole components is limited to a great extent.

The lignocellulose grading utilization method in the prior art is too limited, the utilization efficiency is not too high, in addition, the process is complex, and the cost is not low, so that the method which is simple to operate and low in cost and can improve the comprehensive utilization rate of the forest biomass is very significant in consideration of the economic benefit and the application range in actual application.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for classifying long and short fibers of forest biomass and application thereof, and in particular, the method can effectively classify the long and short fibers of the forest biomass, further fully utilize the enzymolysis advantage of the short fibers of the forest biomass, the additional value-added advantage of the long fibers and improve the comprehensive utilization rate of the forest biomass.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method for classifying long and short fibers of forest biomass, the method for classifying long and short fibers of forest biomass comprising: the method for classifying the forest biomass into long and short fibers comprises the following steps: the method comprises the steps of carrying out rehydration treatment on a forest biomass raw material, boiling in water, drying, soaking in a mixed solution of glacial acetic acid and hydrogen peroxide aqueous solution until fibers are dispersed, washing the dispersed materials with water, and screening to realize grading of long and short fibers.

According to the method, the glacial acetic acid-hydrogen peroxide mixed solution is used as a dispersion medium to carry out fractionation on the forest biomass, so that the separation of long fibers and short fibers in the forest biomass is realized, the enzymolysis advantage of the short fibers is utilized, the uniformity of enzymolysis substrate raw materials is improved, the solid content is increased, the enzyme dosage is reduced, the enzymolysis period is shortened, the enzymolysis efficiency is improved, the operation is simple, the used dispersion medium is low in cost, and the aim of reducing the process cost is fulfilled.

Preferably, the forest biomass feedstock comprises any one or a combination of at least two of wood, bamboo or vine feedstock.

Preferably, the wood comprises any one or a combination of at least two of eucalyptus, poplar, pine, fir or pagodatree.

Preferably, the rehydration treatment is to soak the forest biomass feedstock with water.

Preferably, the soaking time is 4-24h, for example, 6h, 10h, 12h, 15h, 18h, 20h, 22h, etc.

Preferably, the boiling is a water changing repeated boiling.

Preferably, the time of each boiling is 5-30min, for example, 8min, 10min, 12min, 15min, 18min, 20min, 22min, 25min, 28min, etc.

Preferably, the number of repetitions is 3-10 (e.g., 4, 5, 6, 7, 8, 9, etc. repetitions may be possible).

According to the invention, by boiling the forest biomass in water for multiple times, ions in the raw material can be diffused faster, the structure of lignocellulose is damaged to a certain extent, and the subsequent dispersing effect of the raw material is better. And the boiling times are 3-10 times, so that the microcracks of the biomass structure of the forest after boiling are increased, the ion channels are increased, the diffusion coefficient is increased, the subsequent dispersion effect is further enhanced, when the times are too small, the change of the lignocellulose structure after boiling is not large, and when the times are too large, the effect is not obvious.

Preferably, the volume ratio of the glacial acetic acid to the hydrogen peroxide aqueous solution in the mixed solution of the glacial acetic acid and the hydrogen peroxide aqueous solution is 1 (0.5-3), and for example, the volume ratio can be 1:1, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8 and the like.

The compact structure of the forest biomass raw material leads to higher mechanical strength, so that the forest biomass raw material generates stronger stress resistance in the enzymolysis process, is difficult to liquefy, and increases enzymolysis energy consumption, period and cost. According to the invention, the glacial acetic acid and hydrogen peroxide mixed solution with a specific volume ratio is selected, so that the components of the cell wall of the forest biomass can be better destroyed, the compact structure is broken, and the long fibers and the short fibers are effectively separated.

Preferably, the concentration of the aqueous hydrogen peroxide solution is 3% -35%, for example, may be 5%, 10%, 15%, 20%, 25%, 30%, etc.

Preferably, the mixture of glacial acetic acid and aqueous hydrogen peroxide is placed in a constant-temperature water bath kettle when being soaked.

Preferably, the temperature of the constant temperature water bath kettle is 40-80 ℃, for example, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃ and the like can be adopted.

Preferably, the solid to liquid ratio is 1 (5-20) (e.g., 1:7, 1:9, 1:10, 1:12, 1:15, 1:18, etc.) for 3-10 times (e.g., 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, etc.) for the rinse with water.

Preferably, the mesh number of the standard sieve for screening is 20 to 80 mesh, and may be, for example, 25 mesh, 30 mesh, 35 mesh, 40 mesh, 45 mesh, 50 mesh, 55 mesh, 60 mesh, 65 mesh, 70 mesh, 75 mesh, or the like.

According to the invention, long fibers and short fibers can be effectively separated better by controlling the standard mesh number, so that the long fibers and the short fibers can be better classified and utilized.

Other specific point values in the numerical ranges are selectable, and will not be described in detail herein.

In a second aspect, the invention provides an application of the method for classifying long and short fibers of forest biomass according to the first aspect in classification utilization of forest biomass.

In a third aspect, the invention provides a lignocellulose enzymolysis product, which is obtained by subjecting short fibers obtained by the method for classifying long and short fibers of forest biomass in the first aspect to enzymolysis treatment.

In the invention, the short fibers are purified cellulose and hemicellulose components, and the short fibers are adopted for enzymolysis treatment, so that the interference of lignin in the enzymolysis process can be effectively eliminated, the enzymolysis efficiency is effectively improved, the sugar concentration is improved, and the enzymolysis and subsequent fermentation costs are reduced.

Preferably, the solid content of the short fibers in the enzymolysis treatment system is 15-60%, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% and the like.

Preferably, the enzyme amount of the enzymolysis process is 5-20FPU/g DM, for example, 6FPU/g DM, 8FPU/g DM, 10FPU/g DM, 12FPU/g DM, 15FPU/g DM, 17FPU/g DM, 19FPU/g DM, etc.

Preferably, the temperature of the enzymolysis process is 45-55deg.C (for example, 46 ℃, 47 ℃, 48 ℃, 49 ℃, 50 ℃, 51 ℃, 52 ℃, 53 ℃, 54 ℃ and the like) and the time is 24-96 hours (for example, 30 hours, 36 hours, 42 hours, 48 hours, 54 hours, 60 hours, 72 hours, 84 hours, 90 hours and the like).

In a fourth aspect, the invention provides an application of long fibers in preparing enzymolysis sugar manufacturing, compression plate making, pulping and papermaking or textile products, wherein the long fibers are prepared by the method for classifying long and short fibers of forest biomass in the first aspect.

Compared with the prior art, the invention has the following beneficial effects:

1. the mixed solution of glacial acetic acid and hydrogen peroxide is used as a dispersion medium, so that long fibers and short fibers of the forest biomass can be better separated, and the medium is a general industrial chemical and is low in cost.

2. The classified short fiber enzymolysis process can obviously improve the solid content, reduce the enzyme consumption, accelerate the liquefaction process and improve the enzymolysis efficiency.

3. The long fiber after grading can be applied to industries such as enzymolysis sugar manufacturing, compression plate making, pulping and papermaking, textile products and the like.

4. The method improves the comprehensive utilization rate of the forest biomass, has the advantages of simple process, high solid content, low consumption, low equipment requirement and low cost, and is easy to amplify the process.

Detailed Description

In order to further describe the technical means adopted by the present invention and the effects thereof, the following describes the technical scheme of the present invention in combination with the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

Example 1

The embodiment provides a preparation method of a lignocellulose enzymolysis product, which comprises the following steps:

1) Coarse pulverizing poplar sheet to form relatively uniform wood chip of 0.1cm×2 cm;

2) Soaking the poplar scraps in the step 1) in water, and carrying out rehydration treatment for 12 hours;

3) Boiling the raw materials subjected to rehydration in the step 2) in boiling water for 15min, and repeating water exchange for 5 times until the raw materials sink;

4) Drying the boiled raw materials in the step 3), then putting the dried raw materials into a heat-resistant plastic bottle with a screw, soaking the raw materials in a mixed solution of glacial acetic acid and hydrogen peroxide water solution (the concentration of the hydrogen peroxide water solution is 20%) in a volume ratio of 1:1, and putting the raw materials into a constant-temperature water bath kettle when soaking, wherein the temperature is controlled at 60 ℃ until fibers are dispersed;

5) Washing the dispersed raw materials with water, wherein the solid-to-liquid ratio is 1:10, repeatedly washing for 5 times, collecting washing liquid each time to prepare suspension, sieving the suspension with a 40-target standard sieve, respectively collecting long and short fibers, drying, and placing in a shade place;

6) Taking 1g of the short fiber after the fractionation in the step 5), adding 15FPU/g DM cellulase and a citric acid-sodium citrate buffer solution with the pH value of 4.8, placing the short fiber in a 50 ℃ water bath shaking table for reaction for 72 hours under the condition of 120rpm, and collecting to obtain a lignocellulose enzymolysis product.

Example 2

1) Coarse pulverizing Eucalyptus wood slices to obtain relatively uniform 0.1cm×2cm wood chips;

2) Soaking the eucalyptus scraps in the step 1) in water, and rehydrating for 4 hours;

3) Boiling the raw materials subjected to rehydration in the step 2) in boiling water for 5min, and repeating water exchange for 10 times until the raw materials sink;

4) Drying the boiled raw materials in the step 3), then putting the dried raw materials into a heat-resistant plastic bottle with a screw, soaking the raw materials in a mixed solution of glacial acetic acid and aqueous hydrogen peroxide solution (the concentration of the aqueous hydrogen peroxide solution is 35%) in a volume ratio of 1:0.5, and putting the raw materials into a constant-temperature water bath kettle when soaking, wherein the temperature is controlled at 40 ℃ until fibers are dispersed;

5) Washing the dispersed raw materials with water, wherein the solid-to-liquid ratio is 1:20, repeatedly washing for 3 times, collecting washing liquid each time to prepare suspension, sieving the suspension with 80-target standard sieve, respectively collecting long fibers and short fibers, drying, and placing in a shade place;

6) Taking 1g of the short fiber after the fractionation in the step 5), adding 5FPU/g DM cellulase and a citric acid-sodium citrate buffer solution with the pH of 4.8, placing the short fiber in a 45 ℃ water bath shaking table for reaction for 96 hours under the condition of 120rpm, and collecting to obtain a lignocellulose enzymolysis product.

Example 3

1) Carrying out coarse crushing treatment on the bamboo chips to form relatively uniform bamboo chips with the length of 0.1cm multiplied by 2 cm;

2) Soaking the bamboo scraps in the step 1) in water, and carrying out rehydration treatment for 24 hours;

3) Boiling the raw materials subjected to rehydration in the step 2) in boiling water for 30min, and repeating water exchange for 3 times until the raw materials sink;

4) Drying the boiled raw materials in the step 3), then putting the dried raw materials into a heat-resistant plastic bottle with a screw, soaking the raw materials in a mixed solution of glacial acetic acid and aqueous hydrogen peroxide solution (the concentration of the aqueous hydrogen peroxide solution is 3%) in a volume ratio of 1:3, and putting the raw materials into a constant-temperature water bath kettle during soaking, wherein the temperature is controlled at 80 ℃ until fibers are dispersed;

5) Washing the dispersed raw materials with water, wherein the solid-to-liquid ratio is 1:5, repeatedly washing for 10 times, collecting washing liquid each time to prepare suspension, sieving the suspension with a 20-mesh standard sieve, respectively collecting long fibers and short fibers, drying, and placing in a shade place;

6) Taking 1g of the short fiber after the fractionation in the step 5), adding 20FPU/g DM cellulase and a citric acid-sodium citrate buffer solution with the pH of 4.8, placing the short fiber in a water bath shaking table with the solid content of 60 ℃ at the temperature of 55 ℃ for reaction for 36 hours at the speed of 120rpm, and collecting to obtain a lignocellulose enzymolysis product.

Example 4

This example provides a process for the preparation of a lignocellulosic hydrolysate which differs from example 1 only in that the number of boiling in step 3) is 1, the other steps and parameters being the same as in example 1.

Example 5

This example provides a process for the preparation of a lignocellulosic hydrolysate which differs from example 1 only in that the number of boiling in step 3) is 15, the other steps and parameters being the same as in example 1.

Example 6

This example provides a process for preparing a lignocellulosic hydrolysate which differs from example 1 only in that the volume ratio of glacial acetic acid-hydrogen peroxide mixed solution (hydrogen peroxide solution concentration 20%) in step 4) is 1:0.1, and other steps and parameters are the same as in example 1.

Example 7

This example provides a process for the preparation of a lignocellulosic hydrolysate which differs from example 1 only in that the volume ratio of glacial acetic acid-hydrogen peroxide mixed solution (hydrogen peroxide solution concentration 20%) in step 4) is 1:5, the other steps and parameters being the same as in example 1.

Example 8

This example provides a method for preparing a lignocellulosic hydrolysate which differs from example 1 only in that the temperature of the thermostat water bath in step 4) is 30 ℃, and other steps and parameters are the same as in example 1.

Example 9

This example provides a method for preparing a lignocellulosic hydrolysate which differs from example 1 only in that the temperature of the thermostat water bath in step 4) is 90 ℃, and other steps and parameters are the same as in example 1.

Example 10

This example provides a process for the preparation of a lignocellulosic hydrolysate which differs from example 1 only in that the mesh size of the standard sieve in step 5) is 100 mesh, the other steps and parameters being the same as in example 1.

Example 11

This example provides a process for the preparation of a lignocellulosic hydrolysate which differs from example 1 only in that the long fibres obtained in step 5) are used instead of the short fibres of step 6), the other steps and parameters being the same as in example 1.

Comparative example 1

The comparative example provides a method for preparing a lignocellulose enzymolysis product, which comprises the following steps:

2) Dismantling the poplar scraps in the step 1) by adopting a hydrothermal pretreatment method, wherein the hydrothermal pretreatment conditions are as follows: the hydrothermal temperature of the autoclave is 140 ℃, the solid-liquid ratio is 1:10 (w/v), the treatment time is 60min, the solid-liquid separation is carried out after the pretreatment, and the solid material is dried;

3) Taking 1g of the solid material pretreated in the step 2), adding 15FPU/g DM cellulase and a citric acid-sodium citrate buffer solution with the pH value of 4.8, placing the solid material in a 50 ℃ water bath shaking table for reaction for 72 hours at 120rpm, and collecting to obtain a lignocellulose enzymolysis product.

Comparative example 2

This comparative example provides a process for the preparation of a lignocellulosic hydrolysate which differs from example 1 in that the mixture of glacial acetic acid and aqueous hydrogen peroxide in step 4) is replaced by an equal volume of glacial acetic acid solution, the remaining steps and parameters being the same as in example 1.

Comparative example 3

This comparative example provides a process for preparing a lignocellulose enzymatic hydrolysate, which differs from example 1 in that the aqueous hydrogen peroxide solution mixed solution of glacial acetic acid and aqueous hydrogen peroxide solution in step 4) is replaced by an equal volume amount of aqueous hydrogen peroxide solution, and the concentration of aqueous hydrogen peroxide solution is kept unchanged, and the remaining steps and parameters are the same as in example 1.

Comparative example 4

This comparative example provides a process for the preparation of a lignocellulosic hydrolysate which differs from example 1 in that the mixed solution of glacial acetic acid and aqueous hydrogen peroxide in step 4) is replaced by a mixed solution of glacial acetic acid and acetic anhydride in a volume ratio of 1:1, with equal total volume amounts, the remaining steps and parameters being the same as in example 1.

The enzymatic hydrolysis rates of examples 1-11 and comparative examples 1-4 are shown in Table 1, wherein the enzymatic hydrolysis rates of examples 1-11 and comparative examples 2-4 were calculated as follows:

enzymatic yield (glucose yield) =glucose production in enzymatic product (g) ×0.9x100%/mass of cellulose in staple fiber obtained by fractionation (g)

The method for calculating the enzymolysis rate in comparative example 1 comprises the following steps:

enzymolysis rate (glucose yield) =glucose production amount (g) in enzymolysis product×0.9X100%. Mass (g) of cellulose in raw material

Table 1: lignocellulose enzymolysis rate

According to the effect data of the embodiments 1-3, the forest biomass is subjected to long and short fiber classification and then short fiber is subjected to enzymolysis, and the glucose yield is as high as 90.5%. In examples 4 and 5, when the number of boiling times is too small in the method of the present invention, the glucose yield after the hydrolysis of lignocellulose is 85.9%, the effect of improving the enzymolysis rate is not obvious when the number of boiling times is too large; examples 6 to 7 show that when the volume ratio of glacial acetic acid to hydrogen peroxide is too high or too low, the glucose yield is poor after the lignocellulose is hydrolyzed; from the data of examples 8-9, it is clear that when the temperature of the constant temperature water bath kettle is not controlled in the range of the invention, the glucose yield is 85.6% or 86.8% after the lignocellulose is hydrolyzed, and the glucose yield is reduced to some extent; as is clear from example 10, when the mesh number of the standard sieve is too large, the long fibers and the short fibers cannot be well separated, and the final enzymolysis rate is also reduced; as can be seen from example 11, when long fibers are used for enzymolysis, the enzymolysis rate is significantly reduced, because the advantage of enzymolysis of short fibers in lignocellulose is better; as can be seen from comparative example 1, when the forest biomass is subjected to only hydrothermal pretreatment and is not subjected to long fiber and short fiber classification, the glucose yield after lignocellulose enzymolysis is 81.4%, and a significant decrease occurs; as is clear from comparative examples 2 to 4, when other solvents were used instead of the mixed solution of glacial acetic acid and aqueous hydrogen peroxide solution, the final enzymolysis efficiency was also poor.

The applicant states that the present invention is described by way of the above examples as a method of classifying forest biomass into long and short fibers and its application, but the present invention is not limited to the above examples, i.e. it is not meant that the present invention must be practiced in dependence upon the above examples. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.

In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.

Claims

1. A method for classifying long and short fibers of forest biomass, which is characterized by comprising the following steps: rehydrating the forest biomass raw material, boiling in water, drying, soaking in a mixed solution of glacial acetic acid and hydrogen peroxide aqueous solution until fibers are dispersed, washing the dispersed materials with water, and screening to realize grading of long and short fibers;

the rehydration treatment is to soak the forest biomass raw material in water for 4-24 hours;

the boiling is repeated by changing water, the boiling time is 5-30min, and the repetition time is 3-10 times;

the concentration of the hydrogen peroxide water solution is 3% -35%;

the volume ratio of the glacial acetic acid to the hydrogen peroxide water solution in the mixed solution of the glacial acetic acid and the hydrogen peroxide water solution is 1 (0.5-3);

the said water bath is set in 40-80 deg.c water bath while being soaked in the mixture of glacial acetic acid and hydrogen peroxide solution.

2. The method of classifying forest biomass as claimed in claim 1 wherein the forest biomass feedstock comprises any one or a combination of at least two of wood, bamboo or vine feedstock.

3. The method of classifying forest biomass as claimed in claim 2 wherein the wood includes any one or a combination of at least two of eucalyptus, poplar, pine, fir or pagodatree.

4. The method for classifying long and short fibers by forest biomass according to claim 1, wherein the solid-to-liquid ratio is 1 (5-20) and the washing times are 3-10.

5. The method for classifying forest biomass into long and short fibers according to claim 1, wherein the mesh number of the standard sieve for screening is 20-80 mesh.

6. A lignocellulosic hydrolysate, characterized in that it is obtained by enzymatic hydrolysis of short fibers obtained by the method for classifying long and short fibers of forest biomass according to any one of claims 1-5.

7. The lignocellulosic hydrolysate of claim 6 wherein the staple fiber has a solids content in the enzymatic treatment system of 15 to 60%.

8. The lignocellulosic hydrolysate of claim 6 wherein the enzyme is used in an amount of 5 to 20FPU/g DM.

9. The lignocellulosic hydrolysate of claim 6 wherein the enzymatic hydrolysis is carried out at a temperature of 45-55deg.C for a period of 24-96 hours.

10. Use of long fibers in the preparation of enzymatic hydrolysis of sugar, pulp and paper or textile products, characterized in that the long fibers are prepared by the method of classifying forest biomass according to any one of claims 1-5 for long and short fibers.