Novel method for saccharification of ligno-cellulose

Abstract

The invention relates to a new method for processing lignocellulose by saccharification, comprising dilute acid pretreatment, milling and crushing, cellulase compounding and enzymolysis saccharification process. The detail method thereof comprises the following steps: the crushed lignocellulose raw materials are pretreated with dilute acid with the H <+> concentration of 0.01mol / L-0.1mol / L and later milled and crushed, and then acidolysis sugar solution is obtained; at least two types of cellulase are mixed with xylanase for obtaining compound cellulase, and then further enzymolysis saccharification treatment is carried out to the rest solid after enzymolysis and milling for obtaining enzymolysis sugar solution. By using the process that the milling of dilute acid is combined with the one-step enzymolysis of compound enzyme, the hydrolysis sugar yield of the lignocellulose raw materials can be up to more than 90 percent. The method has the advantages of mild reaction condition, simple operation, and high enzymolysis efficiency; moreover, the obtained sugar solution after being processed produces no inhibition to the follow-up fermentation, can be comprehensively utilized, and causes no environmental pollution, etc.

Description

Technical field [0001] The invention relates to a new method for saccharification and treatment of lignocellulose, in particular to a method for improving cellulase-catalyzed lignocellulose saccharification by dilute acid ball milling and cellulase compounding, and belongs to the technical field of biochemical industry. Background technique [0002] Ethanol is a promising fuel to replace limited petroleum. Currently, the main raw material of fuel ethanol is grain, but the output of grain production ethanol is limited. It is the cellulosic material that can really convert a large amount of ethanol. The challenge of converting cellulosic materials to ethanol is low yield and high cost. The pretreatment of cellulosic materials is a key step in the process of converting ethanol. The optimization of this step can significantly increase the hydrolysis rate of cellulose, thereby reducing the production cost of ethanol. [0003] In the process of using lignocellulose to produce ethanol, ...

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Problems solved by technology

[0005] 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 ; U.S. Patent No. 5,562,777 discloses a method for hydrolyzing cellulose and hemicellulose with a strong acid. The mixture of concentrated sulfuric acid and cellulose and hemicellulose with a concentration of 70% to 77% is mixed uniformly at a ratio of 1.25:1 to form a gel , then add water to dilute the concentration of sulfuric acid in the gel to 20% to 30%, then heat to 80°C to 100°C, and treat for 40min to 480min. This process effectively destroys the crystal structure of cellulose, which is beneficial to improve the subsequent processing cellulose degradation rate, but this process also has the disadvantages of high processing temperature, large amount of strong acid, and high production cost; Chinese patent CN1970781 discloses a method for ultrasonically modified cellulase to catalyze lignocellulose saccharification, through pulverization (20 purpose) and alkali treatment (normal temperature, 3% to 8%) to separate the lignin from the raw material, and use activated monomethoxypolyethylene glycol to react with cellulase in citric acid-sodium citrate buffer solution to obtain improved β-glucosidase, amylase and pectinase are mixed to obtain a compound enzyme liquid, and the compound enzyme is added to the pretreated raw material according to the corresponding proportion, and the ultrasonic wave ( 80W~300W) for enzyme-catalyzed reaction, and finally filtered and evaporated under reduced pressure to obtain concentrated sugar solution (25%~35%). This method adopts the method of enzyme modification and compounding to improve the conversion rate of cellulose However, the concentration of lye in this method is too high, which has caused great pressure on the maintenance of production equipment and production costs. Due to the poor effect of alkali treatment in the early stage, the enzymatic hydrolysis process in the later stage is complicated, and operations such as ultrasonic treatment and decompression are further increased. Reduce energy consumption and production cost; Chinese patent CN101255479 discloses a pretreatment method for high-efficiency saccharification of lignocellulose, specifically relates to a method for pretreating lignocellulose with low-concentration lye at room temperature, and its advantage is that the entire operation does not require heating , and use the pretreatment method of wet milling with ultra-low concentration lye with a concentration of 0.1% to 3%, and the lye can be recycled and used, which greatly saves operating costs, but this method does not optimize the use of enzymes, making its enzymes The degradation efficiency is relatively low; Chinese patent CN101092639 discloses a method for enzymatically degrading saccharified crop stalks. After the crushed stalks are pretreated with microorganisms and dilute acid, neutral xylanase and acid cellulase are used to undergo degradative saccharification, and its fibrous Enzyme hydrolysis is carried out in two steps. This method has a high conversion rate and light pollution. However, the combined treatment of microbial fermentation and dilute acid in the pretreatment stage prolongs the operation time to a certain extent. Moreover, enzymatic hydrolysis is carried out in two steps, which is not considered as Substantial compounding operation, its cumbersome process and lengthy time, is not suitable for industrialized mass production

[0006] The problems existing in the prior art can be attributed to: (1) most processes need to use high temperature and high pressure treatment methods, which have high energy consumption and low sugar yield; treatment effect, but the production cost also increases accordingly; (3) acid treatment or alkali treatment is commonly used in the pretreatment stage, but the acid / alkali concentration is higher than 3%, which requires high corrosion resistance of the equipment, thus increasing maintenance and maintenance costs, as well as the extensive use of acid / alkali, and problems such as unreacted acid / alkali that cannot be recovered, have all increased production costs; (4) although some methods have mentioned enzyme compounding, none of them can be quantitatively explained and Analyzing the method of enzyme compounding, and the improvement of enzymatic hydrolysis efficiency is not obvious, it still needs to be operated under auxiliary conditions such as ultrasonic waves, which invisibly further increases the operating cost; (5) or some processes use compound enzymes, but the enzymatic hydrolysis efficiency It is not high, and it still needs to carry out a second single-enzyme enzymatic hydrolysis, which cannot save time, labor and economy.

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