Method for carrying out alkaline pretreatment on plant fiber raw materials for preparing ethanol through enzymolysis and fermentation

A plant fiber and ethanol production technology, which is applied in microorganism-based methods, biochemical equipment and methods, fermentation and other directions, can solve the problem of low utilization rate and ethanol yield, obvious inhibitory effect of inhibitors, inconsistent ethanol tolerance, etc. problems, to achieve the effect of reducing the cost of enzymes, adapting to industrialization and environmental protection, and reducing steam consumption

Active Publication Date: 2012-12-19
NANJING FORESTRY UNIV
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Problems solved by technology

But this method has the following disadvantages: (1) Saccharomyces cerevisiae can tolerate 70-110g / L ethanol, while Pichia stipitis can only tolerate 30-35g / L ethanol
Inconsistent ethanol tolerance greatly limits the total sugar concentration available to yeast
(2) Pichia stipitis always utilizes glucose first, then xylose, the glucose utilization rate and ethanol yield are lower than Saccharomyces cerevisiae, and the xylose utilization rate and ethanol yield are lower
[0009] 2. In addition, genetic engineering can also be used to genetically modify Saccharomyces cerevisiae so that it can ferment hexose and pentose sugars at the same time. However, the fermentation effect of genetically engineered bacteria on the enzymatic hydrolyzate of plant fiber raw materials is unstable and inhibited by inhibitors obvious

Method used

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  • Method for carrying out alkaline pretreatment on plant fiber raw materials for preparing ethanol through enzymolysis and fermentation
  • Method for carrying out alkaline pretreatment on plant fiber raw materials for preparing ethanol through enzymolysis and fermentation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Example 1 Pretreatment of corn stalks

[0025]Crush corn stalks to 2-5cm, use 8% (w / w) alkali, 40% sulfide, and 1:6 (w / v) solid-to-liquid ratio. After idling at 60°C for 0.5h, raise the temperature To 140°C, keep warm for 1h. The corn stalks pretreated by green liquor are washed with water to remove residual chemicals, and the material is refined and squeezed dry to serve as the substrate for subsequent enzymatic hydrolysis. The substrate is analyzed for moisture, cellulose content, and total recovery and glycan recovery are calculated.

[0026] The results showed that the moisture content of 1000g absolute dry corn stalks was 76.90%, 55.39% (dry basis) and 25.43% xylan after green liquor pretreatment, washing and squeezing, and the total recovery rate of green liquor pretreatment was The recovery rate of dextran was 63.31%, the recovery rate of glucan was 91.95%, and the recovery rate of xylan was 63.42%, realizing the effective recovery of polycan.

Embodiment 2

[0027] Example 2 Effect of Substrate Concentration on Enzymatic Hydrolysis of Corn Stalk Cellulose

[0028] Weigh 5.41, 10.82, 16.23, 21.65, 27.06, 32.47g of the green liquor pretreated corn stalks of Example 1 (1.25, 2.50, 3.75, 5.00, 6.25, 7.50g respectively) in six 250mL Erlenmeyer flasks In each Erlenmeyer flask, add 2.5mL of 1mol / L citric acid buffer solution, and pretreat corn stalks with 13.94FPIU / g green liquid according to the amount of cellulase (25FPIU / g dextran, cellulase: β-glucose Glucosidase: xylanase = 1:1.15:6.61) Add corresponding enzymes to each Erlenmeyer flask, add appropriate amount of distilled water to each Erlenmeyer flask to make the total volume of water in the enzymolysis system 50mL, use a glass rod Mix the reaction system well, cover it, and perform enzymatic hydrolysis in a constant temperature shaker at 150 rpm and 50°C for 48 hours. After the hydrolysis, the hydrolyzate was centrifuged at 4000 rpm for 10 min, and the supernatant was taken to m...

Embodiment 3

[0032] Example 3 Cellulase hydrolysis of pretreated corn stalks at 5% substrate concentration (solid-to-liquid ratio 1:20)

[0033] Sterilize 5648.1 mL of distilled water at 121°C for 15 minutes, and add it into a 10 L biochemical reactor that has been sterilized after being cooled. Take 1515.2 g of the corn stalk green liquid pretreatment corn stalks in Example 1 (350 g of absolute dry weight, 1165.2 g of moisture, 193.9 g of cellulose), add it into a 10L biochemical reactor while stirring, and use a small amount of solid hydrogen to Sodium oxide neutralizes to pH 4.8. The temperature of the reaction system was raised to 50°C, 41.42g of cellulase, 12.00g of β-glucosidase and 133.32g of xylanase were added, and hydrolyzed at 48-50°C for 48 hours. After 48 hours of hydrolysis, the hydrolyzate was centrifuged at 7000 rpm for 10 minutes (the centrifuge tube was sterilized beforehand), and the supernatant was used for subsequent concentrated fermentation of the hydrolyzed sugar s...

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Abstract

The invention discloses a method for carrying out alkaline pretreatment on plant fiber raw materials for preparing ethanol through enzymolysis and fermentation. According to the method, firstly, green liquid is used for carrying out alkaline treatment on the air dried plant fiber raw materials; then, under the condition that the substrate w/v concentration being 5 to 15 percent, the cellulose is adopted for batch type hydrolysis for 48 to 72 hours; and after the hydrolysis completion, hydrolysate is subjected to solid-liquid separation, the obtained clear liquid is concentrated to a state that the glucose concentration in the sugar liquid is 100 to 200g/L, hexose in the concentrated sugar liquid is converted into the ethanol through brewer's yeast, the ethanol mash is removed through distillation, and then, the pichia stipitis is used for converting pentose into the ethanol. The method realizes the goals that the mature process and equipment of the paper pulp process are utilized for recovering chemical medicine and heat energy, the consumption of chemicals and the loss of heat energy are reduced, the environment pollution is reduced, the clean production of the ethanol is realized, the efficient proceeding of the enzymolysis and the hexose and pentose fermentation are respectively ensured through the low-substrate-concentration enzyme hydrolysis and the sequential fermentation, particularly, through the pentose fermentation, the ethanol yield of each ton of plant fiber raw materials is improved, and the raw material cost of the ton ethanol is reduced.

Description

technical field [0001] The invention relates to a preparation process of fuel ethanol, in particular to a method for preparing ethanol by enzymolysis and fermentation of alkaline pretreated plant fiber raw materials. Background technique [0002] With the prominence of global resources, energy, and environmental issues and the strengthening of global warming, it is the only way for human beings to find clean and renewable energy, among which fuel ethanol is the first choice due to its unique advantages. Since the development of grain ethanol is restricted by land, agricultural production, food supply, and social economy, fuel ethanol is produced by bioconversion by using abundant wood, grass and other plant fiber raw materials, especially cheap agricultural and forestry wastes, namely Cellulosic ethanol has become one of the effective ways to solve energy and environmental problems, and is currently a research and development hotspot in various countries in the world. [00...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C12P7/10C12P19/14C12R1/84C12R1/865
CPCY02E50/16Y02E50/10
Inventor 勇强余世袁储秋露杨德良黄阳徐勇朱均均李鑫
Owner NANJING FORESTRY UNIV
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