CN102433359A - Biomass pretreatment method - Google Patents

Abstract

The present invention relates to a method for pretreatment of biomass, which can reduce costs and environmental pollution and improve the pretreatment of biomass ethanol fermentation. The method comprises the following steps: (1) removing foreign matter from the biomass, washing it, and crushing it into powder; (2) adding clean water and freezing it naturally; (3) thawing it; (4) stirring and grinding it, and then adding enzymes or other hydrolyzing agents to hydrolyze cellulose and hemicellulose; (5) filtering, wherein the filtrate is used for ethanol fermentation, and the filter residue is the original lignin.

Description

A method of biomass pretreatment

1. Technical field:

The invention relates to a bioenergy production method, in particular to a biomass pretreatment method, which utilizes climatic conditions to freeze and pretreat crop straw, sawdust and weeds.

2. Background technology:

In the background technology, the biomass pretreatment technology to realize the effective hydrolysis of cellulose and hemicellulose in biomass is the key to the production of ethanol by fermentation of biomass. At present, there is a lack of a method suitable for large-scale pretreatment under low-cost, less-polluting, and mild conditions.

The energy consumption of the gas explosion technology is high, and the acid-base treatment not only has high equipment costs, but also serious secondary pollution, which not only pollutes the environment but also produces toxic substances that inhibit ethanol fermentation. Biological methods are time-consuming and ineffective.

The production of lignocellulosic ethanol fuel is in urgent need of a new pretreatment technology that can significantly reduce the cost of biomass pretreatment and eliminate the added or new substances that inhibit the action of ethanol fermentation microorganisms due to pretreatment. the

Freeze-thaw techniques are widely used for cell wall disruption. Indoor artificial freezing and thawing technology can promote enzymatic hydrolysis of cellulose and hemicellulose in straw into monosaccharides.

Such pretreatment does not require high temperature and organic solvents, avoids the recombination of lignin and cellulose and its own re-agglomeration, and has low requirements for acid and alkali resistance of pretreatment equipment. However, the energy consumption of artificial refrigeration required to achieve freezing increases the cost, which limits the large-scale industrial application of this technology.

Northeast my country, Inner Mongolia and other places have a long period of low temperature in winter, and the industrial utilization of natural freezing has been insufficient. These areas generate a large amount of biomass resources every year.

In winter, during the regular stacking of forest wood and straw biomass, because the wax layer on the surface of the biomass prevents rainwater from infiltrating, freezing only occurs on the damaged surface of wood chips and straw, and the waste heat caused by microbial fermentation is even released in the deep layer.

3. Contents of the invention:

In order to solve the deficiencies in the above-mentioned background technology, the present invention provides a biomass pretreatment method, which can reduce cost and environmental pollution, and improve biomass ethanol fermentation pretreatment.

To achieve the above object, the technical solution adopted in the present invention is:

A method for biomass pretreatment, characterized in that it comprises the following steps:

(1) Remove foreign matter from the biomass, wash it, and crush it into powder;

(2) Add water and freeze naturally;

(3) Unfreeze:

(4) After stirring and grinding, add enzymes or other hydrolyzing agents to hydrolyze cellulose and hemicellulose;

(5) Filtration, the filtrate is used for ethanol fermentation, and the filter residue is the original lignin.

In step (2), natural freezing is the temperature condition. An example is winter weather conditions in regions that can drop below -20°C.

In step (3), the thawing is natural thawing or artificial thawing.

Biomass includes straw, wood or weeds.

The pretreated biomass is used in the production of cellulose, hemicellulose and lignin products from all biomass.

Compared with prior art, the advantages and effects that the present invention has are as follows:

1. The present invention does not need high pressure, high temperature and artificial refrigeration.

2. The present invention does not produce papermaking black liquor and secondary substances that inhibit yeast ethanol fermentation.

3. The present invention can obtain raw lignin.

4. The present invention is suitable for large-scale production.

5. The invention has low cost and is simple and convenient to use.

Fourth, the specific implementation method:

The invention relates to a biomass pretreatment method. The specific process is: in winter, in areas where the temperature can drop below -20°C, large-scale freezing of straw and other biomass is carried out by natural freezing. After the temperature rises, natural thawing and artificial thawing, enzymatic hydrolysis or other hydrolysis of biomass begins. Take wheat straw as an example: After removing foreign matter such as dust, metal, plastic, etc., the straw is cut into pieces to promote the biomass to absorb water. Put it into a low-temperature-resistant container, add water in small amounts and several times and keep stirring until the straw no longer absorbs water. During the initial period of natural freezing, moderate agitation should be continued. After the arrival of spring, the frozen straw begins to thaw, or thaw artificially. The thawed straw enters the stage of enzymatic hydrolysis, or is further hydrolyzed by other methods. Biomass includes all crop residues, grasses, wood and fibrous plants.

The principle of the present invention is: the volume of water of equal volume will increase after freezing, and the volume will shrink after freezing and melting. Therefore, it can be used to destroy cell walls. After absorbing water, the plant straw and stem and leaf cells will swell due to the water absorption of the contents after absorbing water. After freezing, the volume of the cells will increase due to the freezing of water in and around the cells, and the volume will shrink again after freezing and thawing, thus The cell wall and surrounding structures are torn, and the crystalline structure of organic matter formed by lignin, cellulose, and hemicellulose is destroyed. Compared with delignification in pulp and paper making, the pretreatment purpose of biomass ethanol fermentation is to relax the natural structure between the various components of biomass, and to enzymatically hydrolyze the cellulose and hemicellulose in it to become fermentable to produce ethanol The monosaccharide provides conditions, lignin can remain in the hydrolyzate and fermentation broth without affecting the polysaccharide hydrolysis and fermentation state, until finally recycled.

Example 1:

Crush the wheat straw into powder, add water to the cement floor and stir until the straw powder no longer absorbs water, keep it at a low temperature below -20°C for 12 hours, and then melt it naturally at room temperature. After the melted straw is vigorously stirred in the heat preservation container, cellulase and hemicellulase are added for enzymatic hydrolysis. The filtered filtrate contains monosaccharides after hydrolysis of cellulose and hemicellulose, and the filter residue is original lignin.

Example 2:

Crush wheat sawdust into powder, put it into a pool to absorb water for 12 hours, drain excess water, keep it at a low temperature below -20°C for 12 hours, and then melt it naturally at room temperature. Stir the melted straw, grind it into a slurry, and then enter the subsequent enzymatic hydrolysis or hydrolysis in other ways.

Claims (5)

1. pretreated method of biomass is characterized in that may further comprise the steps:

(1) biomass is removed foreign matter, clean, be crushed into Powdered;

(2) add clear water, freezing naturally;

(3) thaw:

(4) stir, grind the back and add enzyme or other hydrolytic reagent hydrocellulose and semicellulose;

(5) filter, filtrating is used for ethanol fermentation, and filter residue is the log quality.

2. the pretreated method of a kind of biomass according to claim 1 is characterized in that: in the step (2), freezing naturally is temperature condition, can drop to the geographic winter climate condition below-20 ℃.

3. the pretreated method of a kind of biomass according to claim 1 and 2 is characterized in that: in the step (3), thaw for thaw naturally or manual work thaw.

4. the pretreated method of a kind of biomass according to claim 3, it is characterized in that: biomass comprise stalk, timber or weeds.

5. the pretreated method of a kind of biomass according to claim 4 is characterized in that: pretreated biomass are used for the production of all biomass Mierocrystalline celluloses, semicellulose and lignin product.