Pre-treatment method for highly-effective saccharification of lignocellulose

Abstract

The invention discloses a pretreatment method for effectively saccharifying lignocellulose, particularly discloses a pretreatment method of lignocellulose with room-temperature light-concentration lye, characterized in the method comprises the steps of coarse grinding, lye wetmilling, alkali recovery and enzymolysizing. The ground lignocellulose is mixed with univalent metal lye having a concentration of 0.1% to 3%, solid and liquid are separated under room temperature after wet grinding, wherein the liquid is used for recovering univalent metal lye, and the solid, namely the modified lignocellulose, is used for further enzymolysizing for preparing liquid glucose. According to the invention, lignocellulose is used as the raw material, room temperature condition without external heating can be selected, low-concentration lye is pretreated, the lye can be effectively recovered, the enzymolysis efficiency is improved, the glucose yield is increased, the cost is lowered, the economical efficiency is enhanced, and drawbacks of high energy consumption, low glucose recovery rate, and high equipment requirements in current lignocellulose pretreatment method are made up.

Description

technical field [0001] The invention belongs to the technical field of biochemical industry, and in particular relates to a pretreatment method for high-efficiency saccharification of lignocellulose, in particular to an energy-saving and environment-friendly normal-temperature low-concentration alkali pretreatment method. Background technique [0002] With the depletion of global oil resources, serious atmospheric carbon dioxide pollution and economic development, it has become an inevitable trend to use biomass raw materials to produce bioenergy and biochemical products to replace petrochemical products. At present, the production of most biochemical products depends on the raw materials of food crops such as sugarcane and corn, which has the disadvantage of high production cost and can only be applied in a few high value-added fields. In addition, the use of food crops as raw materials for biofuel production has the danger of triggering and aggravating food problems. The ...

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Problems solved by technology

Currently lignocellulose pretreatment methods include physical methods (such as pulverization), chemical methods (such as acid and alkali treatment), physicochemical methods (such as steam explosion) and biological methods, but these processing methods have the following problems: physical methods such as The energy consumption of a single pulverization process is high, accounting for about 50% to 60% of the total energy consumption in the lignocellulose saccharification process; the acid or alkali concentration required for chemical pretreatment is 10% to 77%, and the treatment temperature is 100°C to 120°C , has the disadvantages of high energy consumption and high requirements for equipment corrosion resistance; the loss of hemicellulose after treatment by physical and chemical methods such as steam explosion method reaches 60% to 70%, and the solid yield of raw materials is only 30% to 50%, which greatly reduces Sugar yield and raw material utilization rate; the reaction period of the biological method is long, and at the same time, the bacteria will use part of the cellulose and hemicellulose, which will reduce the hydrolysis yield

[0004] Chinese patent CN1806945 discloses a method of using straw pretreatment and enzymatic hydrolysis process to completely enzymatically hydrolyze straw cellulose. The straw is first subjected to steam explosion treatment, and then washed with hot water to remove hemicellulose polysaccharides. After drying, it is mixed with ionic liquid Mixing, microwave heating or direct heating, and then repeatedly rinse the treated straw with water, the solvent in the washing liquid can be recovered by distillation and other methods, and rinse the treated straw with cellulose in a pH4.8 buffer solution at 50 °C After 48-72 hours of enzymatic hydrolysis, the enzymatic hydrolysis rate of cellulose can reach 100%, but the above-mentioned defects of steam explosion treatment still exist, and heating is still required after steam explosion, which consumes a lot of energy, the production cost is too high, and the process is cumbersome Chinese patent CN1970781 discloses a method for ultrasonic synergistic modification of cellulase to catalyze lignocellulose saccharification, by pulverizing (20 orders) and alkali pretreatment (normal temperature, 3% to 8%) to separate the lignin in the raw material, and using Activated monomethoxypolyethylene glycol reacts with cellulase in citric acid-sodium citrate buffer solution to obtain modified cellulase, and the modified cellulase is mixed with β-glucosidase, amylase and fruit Glue enzymes are mixed to obtain a compound enzyme liquid, and the compound enzyme is added to the pretreated raw materials according to the corresponding proportion, and the enzyme catalyzed reaction is carried out with ultrasonic waves (80-300W), and finally filtered and evaporated under reduced pressure to obtain concentrated sugar liquid (25% ~35%), but the concentration of lye in this method is too large, which has caused huge pressure on the maintenance of production equipment and production costs. Due to the poor effect of alkali treatment in the early stage, the complexity of the enzymatic hydrolysis process in the later stage has been caused. Pressing and other operations further increase energy consumption and production costs; Chinese patent CN101121175 discloses a method for alkali ozone pretreatment of straw, mixing crushed straw with lime water, wherein straw (calculated as dry matter) accounts for the total amount of feed liquid Lime accounts for 0.3% to 1% of the total amount of feed liquid. Low-flux ozone is introduced into the mixed feed liquid and then left to stand. This process improves the lignin and fiber content of straw during subsequent processing The degradation rate of cellulose can speed up the subsequent processing speed of straw, but the cost of ozone is too high, which is not suitable for industrial production; Chinese patent CN101153305 discloses a method for pretreatment of straw fiber raw materials. Solid Ca(OH) 2 (amount of 3% to 35%) and water (amount of 3 to 8 times) are mixed evenly, and treated at 70°C to 125°C for 10 to 60 minutes, and the obtained material is wet pulverized by adding water (3 to 8 times) to obtain a slurry Then treat it at 70°C-125°C for 10-60 minutes, neutralize the obtained material with concentrated acid, such as sulfuric acid, hydrochloric acid, etc., adjust the pH value to the optimum action condition of cellulase, and then carry out enzymatic hydrolysis , the method uses cheap and readily available Ca(OH) 2 Alkaline hydrolysis, and the method of wet pulverization into slurry is adopted, which improves the effect and reduces the cost compared with the above-mentioned other methods, but the treatment method of repeating heating twice is not only cumbersome to operate, but also has not completely solved the problem. The energy consumption problem caused by heating, and the CaSO produced in the process 4 and other by-products have caused environmental protection burden; U.S. Patent No. 5,562,777 discloses a method for strong acid hydrolysis of cellulose and hemicellulose, and the concentration is the mixture of concentrated sulfuric acid of 70% to 77% and cellulose and hemicellulose by 1.25: 1 Mix evenly to form a gel, then add water to dilute the sulfuric acid concentration in the gel to 20% to 30%, then heat to 80°C to 100°C, and treat for 40 to 480min. This process effectively destroys the crystallization of cellulose structure, which is conducive to improving the degradation rate of cellulose during subsequent processing, but this process also has disadvantages such as high processing temperature, large amount of strong acid, and high production cost.

[0005] The problems in the prior art can be summarized as follows: (1) heat treatment method is used, energy consumption is high, sugar yield is low; (2) chemical treatment and Combination of special operations such as steam explosion, ultrasonic wave, modified enzyme, decompression, ozone, etc., but the production cost also increases accordingly; (3) acid hydrolysis or alkali hydrolysis methods are generally used, but the acid / alkali concentration is higher than 3%, which is harmful to The maintenance and maintenance costs of equipment, and the extensive use of acid / alkali, and the unreacted acid / alkali cannot be recovered, all increase production costs; (4) Some methods use cheap and easy-to-get Ca(OH)2 undergoes alkaline hydrolysis, and the by-products such as CaSO4 produced in the process cause environmental protection burden

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