阅读说明：本技术 一种木质纤维素生物质联产乙醇和富含酚类生物油的方法 (Method for co-producing ethanol and biological oil rich in phenols by using lignocellulose biomass ) 是由 李秉硕 杨天华 李润东 刘懿萱 开兴平 于 2019-12-04 设计创作，主要内容包括：本发明公开了由木质纤维素生物质联产乙醇和富含酚类生物油的方法,涉及生物质能源技术领域。第一步,纤维素乙醇发酵过程：木质纤维素生物质经稀酸预处理去除大部分半纤维素及部分木质素,对预处理后的原料进行酶解得到以C6为主的酶解液,对酶解液进行发酵产乙醇；第二步,乙醇发酵剩余残渣亚/超临界液化制富含酚类生物油过程：以乙醇蒸馏后的乙醇发酵废水为溶剂,对乙醇发酵剩余酶解残渣(主要为木质素)进行亚/超临界液化反应,得到以酚类化合物为主的液体产物生物油。本发明在获得纤维素乙醇的同时,建立酶解残渣亚/超临界液化制备富含酚类生物油的新方法,有利于提高木质纤维素生物质生物炼制水平。(The invention discloses a method for co-producing ethanol and biological oil rich in phenols by lignocellulose biomass, and relates to the technical field of biomass energy. Step one, the cellulose ethanol fermentation process: pretreating the lignocellulose biomass by dilute acid to remove most of hemicellulose and part of lignin, carrying out enzymolysis on the pretreated raw material to obtain an enzymolysis solution mainly containing C6, and fermenting the enzymolysis solution to produce ethanol; step two, the process of preparing the biological oil rich in phenols by ethanol fermentation residual residue through sub/supercritical liquefaction: taking ethanol fermentation wastewater after ethanol distillation as a solvent, and performing a sub/supercritical liquefaction reaction on the residual enzymolysis residues (mainly lignin) after ethanol fermentation to obtain a liquid product bio-oil mainly containing phenolic compounds. The invention establishes a new method for preparing the biological oil rich in phenols by sub/supercritical liquefaction of the enzymolysis residues while obtaining the cellulosic ethanol, and is beneficial to improving the biological refining level of the lignocellulose biomass.)

1. A method for co-producing ethanol and biological oil rich in phenols by using lignocellulose biomass is characterized by comprising the following steps:

step 1, pretreatment of lignocellulosic feedstock

The method takes the wood fiber biomass with the grain diameter of 0-5mm as a raw material, destroys the compact structure of the wood fiber biomass through dilute acid pretreatment, reduces the crystallinity of cellulose, and increases the accessibility of cellulase;

step 2, saccharification and fermentation process of pretreated raw materials to produce ethanol

Carrying out saccharification fermentation on the raw material pretreated by the dilute acid to produce ethanol, distilling fermentation liquor after fermentation is finished to obtain ethanol, and obtaining ethanol fermentation wastewater as the rest;

step 3, the process of preparing the biological oil rich in phenols by sub/supercritical liquefaction of the fermentation residual residues

Taking the solid residue left after saccharification and fermentation of the raw material pretreated in the second step as a raw material, selecting a solvent, carrying out a subcritical/supercritical liquefaction reaction on the solid residue in a high-pressure reaction kettle, cooling the reaction kettle to room temperature after the reaction is finished, opening the reaction kettle, pouring a solid-liquid mixture in the kettle into a beaker, washing the reaction kettle with ethanol, and merging the washing liquid into the beaker;

the fourth step, separation of bio-oil

Filtering the solid-liquid mixture obtained in the third step by a filter membrane to respectively obtain a liquid phase product and a solid phase product, extracting the liquid phase product by dichloromethane to obtain a dichloromethane phase-soluble phase, and extracting the solid phase product by acetone to obtain a corresponding acetone phase-soluble phase; after removal of the dichloromethane and acetone separately by a rotary evaporator, the remaining liquid product is called bio-oil.

2. The method according to claim 1, wherein the diluted acid in the step 1 is any one of diluted sulfuric acid, diluted nitric acid and diluted hydrochloric acid, the mass fraction is 0.5-2.0%, the pretreatment time is 10-60min, and the pretreatment temperature is 90-200 ℃.

3. The method of claim 1, wherein the saccharification fermentation in step 2 is any one of synchronous saccharification fermentation, fractional saccharification fermentation and synchronous saccharification co-fermentation, the enzyme used in the saccharification process is cellulase in an amount of 20-60U/g of raw material, the temperature of the enzymolysis fermentation is 28-55 ℃, the time is 12-72h, and the pH value is 4.0-7.0.

4. The method as claimed in claim 1, wherein the liquefaction temperature in step 3 is 200-400 ℃ and the time is 0-120min, and the solvent is any one of water and organic solvent and a mixed solvent of water and the organic solvent in any ratio.

5. The method of claim 4, wherein the organic solvent is methanol, ethanol, acetone, cyclohexane, ethanol fermentation wastewater.

6. The method of claim 1, wherein the lignocellulosic biomass feedstock comprises any one of corn stover, corn cobs, rice stover, wheat straw, cotton stover, wood chips, bark, twigs, fallen leaves, and switchgrass, and any mixed feedstock thereof.

Technical Field

The invention belongs to the field of biomass energy, and relates to a method for co-producing ethanol and phenol-rich bio-oil by using lignocellulose biomass.

Background

The dual challenges of fossil energy scarcity and climate change force energy demand infrastructure to change, requiring rapid development of renewable energy sources, particularly biofuels. The technology for preparing bio-oil by sub/supercritical liquefaction of lignocellulose biomass is widely favored in recent years and is one of the biomass conversion modes with great development potential at present. However, since the thermal decomposition temperature intervals of cellulose, hemicellulose and lignin which form the three major components of the lignocellulosic biomass are greatly different, the polycondensation reaction among pyrolysis and liquefaction products of the components and the generation of residues are increased, thereby reducing the yield of the bio-oil. The grading utilization of three major components of lignocellulose realized by a biorefinery technology has become a research hotspot. Cellulose can be converted into ethanol through saccharification and fermentation, and fermentation residues with lignin as a main component can be subjected to sub/supercritical liquefaction reaction to obtain liquid bio-oil rich in phenolic compounds. Compared with the direct combustion utilization mode of the residual fermentation residues in the traditional cellulosic ethanol fermentation process, the sub/supercritical liquefaction of the residual residues has important significance for realizing high-efficiency conversion and high-valued utilization of the residual residues, and simultaneously has certain practical significance for improving the overall economic benefit of the cellulosic ethanol production process.

Patent CN 102154381 a discloses a method for co-producing two kinds of bio-fuels, bio-ethanol and bio-diesel, using lignocellulose as raw material. Carrying out ethanol fermentation on cellulose solid obtained after pretreatment of a lignocellulose raw material; in the pretreatment process, the hemicellulose hydrolysate is used for microbial oil fermentation; meanwhile, yeast thalli obtained by ethanol fermentation and thalli residues obtained after oil extraction are hydrolyzed and used as nitrogen sources to be reused in the ethanol fermentation and microbial fermentation processes, so that the wastewater discharge in the ethanol production is reduced.

Patent CN 103923948A discloses a method for co-producing ethanol, biodiesel and methane by using lignocellulose as a raw material. Pretreating lignocellulose raw materials, carrying out enzymolysis to produce sugar, fermenting ethanol, adding livestock and poultry manure into enzymolysis residues, carrying out anaerobic fermentation to prepare biogas, converting biogas residues through decaying insects, using organic wastewater as culture microalgae, and using insect fat and microalgae as preparation biodiesel.

The literature 'research on ethanol and methane co-production potential of four northern energy herbaceous plants' (the solar energy science, 2017,38 (8): 62-68) discloses a method for producing ethanol by simultaneous saccharification and fermentation of steam exploded wheatgrass, steam exploded elymus, steam exploded esparto grass and steam exploded silvergrass and producing methane by anaerobic fermentation of all residues of the ethanol fermentation, wherein the ethanol and methane co-production improves the conversion rate of holocellulose.

The above-mentioned technology reports a method for co-producing bioethanol, methane and biodiesel from lignocellulose, and the common point is that the residual residue in the production process of cellulosic ethanol is utilized in a high-value manner, and the biodiesel or methane is obtained mainly by biotransformation, so that the conversion utilization efficiency of holocellulose is improved. According to the invention, on the basis of cellulose ethanol fermentation, the residual lignin after fermentation is converted into the biological oil rich in phenolic compounds by a hydrothermal liquefaction technology, so that the utilization efficiency of cellulose and lignin is improved. The method not only makes full use of the residual solid residues in the ethanol fermentation, but also synergistically treats the wastewater generated in the ethanol fermentation process, and improves the degradability of the wastewater.

Disclosure of Invention

The invention aims to provide a method for co-producing ethanol and biological oil rich in phenols by using lignocellulose biomass, which realizes the efficient conversion and utilization of all components of lignocellulose. In order to achieve the purpose, the invention adopts the following technical scheme:

a method for co-producing ethanol and biological oil rich in phenols by using lignocellulose biomass comprises the following steps:

(1) pretreating a lignocellulose raw material: the method takes the wood fiber biomass with the grain diameter of 0-5mm as a raw material, destroys the compact structure of the wood fiber biomass through dilute acid pretreatment, reduces the crystallinity of cellulose, and increases the accessibility of cellulase.

(2) The process for producing the ethanol by saccharification and fermentation of the pretreated raw materials comprises the following steps: and (3) carrying out saccharification fermentation on the raw material pretreated by the dilute acid to produce ethanol, distilling the fermentation liquor after the fermentation is finished to obtain ethanol, and obtaining ethanol fermentation wastewater as the rest.

(3) Process for preparing phenol-rich bio-oil by sub/supercritical liquefaction of fermentation residual residues

Taking the solid residue left after the saccharification and fermentation of the raw material pretreated in the second step as a raw material, selecting a solvent, carrying out a subcritical/supercritical liquefaction reaction on the solid residue in a high-pressure reaction kettle, cooling the reaction kettle to room temperature after the reaction is finished, opening the reaction kettle, pouring a solid-liquid mixture in the kettle into a beaker, cleaning the reaction kettle with an organic solvent, and adding a washing solution into the beaker.

(4) Separation of bio-oil

And (3) filtering the solid-liquid mixture obtained in the third step by using a filter membrane to respectively obtain a liquid-phase product and a solid-phase product, extracting the liquid-phase product by using dichloromethane to obtain a dichloromethane phase-soluble phase, and extracting the solid-phase product by using acetone to obtain a corresponding acetone phase-soluble phase. After removal of the dichloromethane and acetone separately by a rotary evaporator, the remaining liquid product is called bio-oil.

The diluted acid in the pretreatment is any one of diluted sulfuric acid, diluted nitric acid and diluted hydrochloric acid, the mass fraction is 0.5-2.0%, the pretreatment time is 10-60min, and the pretreatment temperature is 90-200 ℃.

The saccharification and fermentation is any one of synchronous saccharification and fermentation, step-by-step saccharification and fermentation and synchronous saccharification and co-fermentation, the enzyme used in the saccharification process is cellulase, the dosage is 20-60U/g of raw material, the temperature of enzymolysis and fermentation is 28-55 ℃, the time is 12-72h, and the pH value is 4.0-7.0.

The liquefaction temperature is 200-400 ℃, the time is 0-120min, and the solvent is any one of water and organic solvents (methanol, ethanol, acetone, cyclohexane and ethanol fermentation wastewater) and a mixed solvent of water and the organic solvents in any proportion.

The lignocellulose biomass raw material comprises any one of corn straw, corncob, rice straw, wheat straw, cotton straw, wood, sawdust, bark, twigs, fallen leaves and switchgrass and any mixed raw material.

The invention has the beneficial effects that:

the invention provides a novel lignocellulose biorefinery method, which can obtain bioethanol and high-added-value phenol bio-oil and realize the fractional utilization of cellulose and lignin.

The organic wastewater generated in the ethanol fermentation process is used as a solvent for the sub/supercritical liquefaction reaction of the residual residues in the ethanol fermentation, so that the water consumption required in the process is reduced, and meanwhile, the hydrothermal treatment is performed on organic matters in the ethanol fermentation wastewater, so that the improvement of the degradability of the wastewater is facilitated.

The biological oil rich in phenolic compounds obtained by the invention can be further used for preparing liquid fuels such as cyclanes and the like by catalytic hydrogenation and upgrading.

Drawings

In order to facilitate understanding for those skilled in the art, the present invention will be further described with reference to the accompanying drawings.

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The invention is illustrated in detail by the following examples in conjunction with fig. 1: