阅读说明：本技术 一种两步预处理柠条的方法 (Method for pretreating caragana microphylla in two steps ) 是由 李文超 韩琳洁 钟成 贾士儒 谢燕燕 于 2019-09-29 设计创作，主要内容包括：本发明提供了一种两步预处理柠条的方法,以柠条为原料,采用蒸汽爆破-乙二胺两步预处理技术。首先将柠条进行蒸汽爆破预处理,得到预处理原料,然后与乙二胺混匀置于密闭反应容器中,在高温条件下进行反应,得到两步预处理的柠条。本发明采用两步预处理,能够有效去除木质纤维素中的半纤维素和木质素、保留纤维素,有效提高纤维素和半纤维素的酶解效率。采用两步预处理技术,可以有效降低直接采用乙二胺预处理的强度和减少乙二胺的用量。(The invention provides a method for pretreating caragana microphylla in two steps, which takes caragana microphylla as a raw material and adopts a two-step pretreatment technology of steam explosion-ethylenediamine. Firstly, performing steam explosion pretreatment on caragana microphylla to obtain a pretreatment raw material, then uniformly mixing the pretreatment raw material with ethylenediamine, placing the mixture in a closed reaction container, and reacting at a high temperature to obtain the caragana microphylla pretreated by two steps. The method adopts two-step pretreatment, can effectively remove hemicellulose and lignin in lignocellulose, retain cellulose, and effectively improve the enzymolysis efficiency of the cellulose and the hemicellulose. By adopting a two-step pretreatment technology, the strength of direct ethylene diamine pretreatment can be effectively reduced, and the dosage of ethylene diamine can be reduced.)

1. A two-step pretreatment method of caragana microphylla comprises the following steps:

(1) putting the pulverized caragana microphylla into a steam explosion reaction cylinder, introducing high-temperature steam to enable the pressure to reach a specified value, maintaining a certain reaction time, quickly opening an exhaust valve, collecting and washing the materials with water, and drying to obtain caragana microphylla subjected to steam explosion pretreatment;

(2) mixing the caragana microphylla subjected to steam explosion with ethylenediamine uniformly, placing the mixture in a closed reactor, heating for reaction, taking out the reactor after a certain period of time, quickly cooling, and taking out the material to obtain the caragana microphylla subjected to ethylenediamine pretreatment.

2. The pretreatment method according to claim 1, wherein the steam explosion reaction is carried out under a pressure of 1.8 to 2.5MPa for 3 to 10 min.

3. The pretreatment method as claimed in claim 1, wherein the temperature of the heating reaction is 120-210 ℃.

4. The pretreatment method according to claim 1, wherein the heating reaction time is 10 to 50 min.

5. The pretreatment method according to claim 1, wherein the mass-to-volume ratio of caragana microphylla to ethylenediamine is 1 g: (1-4) mL.

6. The pretreatment method of claim 1, wherein the caragana microphylla is pretreated by steam explosion and ethylenediamine, and then washed with water, filtered or heated to recover ethylenediamine, so as to obtain a solid after the two steps of pretreatment, and then dried.

7. The pretreatment method of claim 1, wherein the size of the pulverized caragana microphylla is 20 mesh, and the humidity is 1-80%.

Technical Field

The invention belongs to the technical field of biomass refining, and particularly relates to a method for pretreating caragana microphylla in two steps.

Background

Fossil feedstock is a non-renewable resource and sustainability around the development of fossil feedstock is becoming an increasingly more challenging task. Meanwhile, the exploitation and utilization of fossil resources in large quantities also brings about serious environmental problems. Therefore, in recent years, the search for renewable alternative resources is facing increasing pressure. The lignocellulose raw material is a renewable biomass resource with wide distribution and rich yield. Lignocellulose can be used to produce a variety of chemical products (e.g., fuel ethanol, lactic acid, etc.). However, the strong cross-linked network structure of lignocellulose makes it very resistant to microbial degradation and physicochemical factors. This structure makes the utilization efficiency of cellulose, hemicellulose, lignin and other components extremely low. Therefore, pretreatment is usually required to change the structure of lignocellulose and promote the utilization of each component.

The existing pretreatment methods include physical methods such as mechanical pulverization, microwave pretreatment, freezing pretreatment, ultrasonic treatment, etc.; chemical methods such as acids, bases, organic solvents, ionic liquids, and the like; physical and chemical methods such as steam explosion pretreatment, ammonia fiber explosion pretreatment, high-temperature liquid water pretreatment and the like; biological methods such as biological enzyme pretreatment, white (brown) rot fungus pretreatment, etc. Although a single preprocessing method is highly targeted, the effect tends to be biased. Therefore, different pretreatment methods are combined in the application process, the pretreatment effect and the separation efficiency of components are expected to be improved, and the process is more economical.

The steam explosion method is a physical and chemical method, can effectively realize the separation of chemical components such as hemicellulose and the like, does not need to add chemicals, has no pollution to the environment and lower energy consumption, and is a lignocellulose high-efficiency pretreatment technology which is widely applied and has lower cost in recent years. Ethylenediamine pretreatment has been developed in recent years to provide good pretreatment of both herbaceous and woody plants. The ethylenediamine can open ether bonds connected between the lignin and the hemicellulose, so that the lignin is removed, the cellulose and the hemicellulose are retained to a greater extent, meanwhile, the crystal form of the cellulose can be effectively changed, and the enzymolysis accessibility of the lignocellulose is greatly improved. Meanwhile, the ethylenediamine is an organic base, the boiling point of which is 119 ℃, and can be recovered by heating and the like.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a two-step pretreatment method for caragana microphylla, which can significantly improve the conversion rate of cellulose and hemicellulose of caragana microphylla of woody plants and reduce the amount of ethylenediamine used.

The invention provides a method for pretreating caragana microphylla in two steps, which comprises the following steps:

(1) and (3) putting the pulverized caragana microphylla into a steam explosion reaction cylinder, introducing high-temperature steam to enable the pressure to reach a specified value, maintaining a certain reaction time, quickly opening an exhaust valve, collecting and washing the materials with water, and drying to obtain the caragana microphylla subjected to steam explosion pretreatment.

(2) Mixing the caragana microphylla subjected to steam explosion with ethylenediamine uniformly, placing the mixture in a closed reactor, heating for reaction, taking out the reactor after a certain period of time, quickly cooling, and taking out the material to obtain the caragana microphylla subjected to ethylenediamine pretreatment.

Preferably, the steam explosion reaction condition is 1.8-2.5Mpa, and the reaction time is 3-10 min.

Preferably, the temperature for heating the reaction is 120-210 ℃.

Preferably, the heating reaction time is 10 to 50 min.

Preferably, the mass volume ratio of the caragana microphylla to the ethylenediamine is 1 g: (1-4) mL.

Preferably, the caragana microphylla is subjected to steam explosion and ethylenediamine pretreatment, and then the caragana microphylla is washed with water, filtered or heated to recover ethylenediamine, so that a solid obtained after the two steps of pretreatment is obtained, and then the solid is dried.

Preferably, the size of the pulverized caragana microphylla is 20 mesh sieve, and the humidity is 1% -80%.

The steam explosion-ethylenediamine two-step pretreatment method provided by the invention can effectively improve the glucose yield of caragana microphylla. In the steam explosion process, hemicellulose and other components in the raw materials are removed, the solid recovery rate is 60-80%, so that compared with direct ethylenediamine pretreatment, the consumption of ethylenediamine in the second pretreatment is reduced by 20-40%, the results of the implementation example of the invention show that the yield of glucose obtained after the caragana microphylla ethylenediamine pretreatment enzymolysis is 89.71%, and compared with 70.62% of direct ethylenediamine pretreatment enzymolysis, the yield is obviously improved.

Detailed Description