Biomass graded utilization method based on lignin priority

Abstract

The present invention provides a biomass fractionation and utilization method based on lignin priority, comprising the following steps: a lignin component priority separation step: pre-treating lignocellulosic biomass to obtain a solid residue, lignin, and its derivatives; a catalytic conversion step of the lignin and its derivatives: using catalytic thermochemical conversion technology, converting the lignin and its derivatives into hydrocarbon compounds in one or two steps; and an enzymatic hydrolysis and fermentation step of the solid residue: saccharifying and fermenting the solid residue produced in the lignin component priority separation step in steps to obtain bioalcohol, wherein the solid residue is cellulose and hemicellulose. The biomass fractionation and utilization method based on lignin priority separation can effectively inhibit condensation reactions between lignin macromolecules and significantly reduce the difficulty of subsequent conversion of lignin and its derivatives. The conversion of hydrocarbon compounds and bioalcohol improves the conversion and utilization efficiency of all components of forestry biomass resources with high lignin content.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass refining, in particular to a hierarchical utilization method of biomass based on lignin priority. Background Art

[0002] As the only renewable energy source that can be directly converted into liquid fuels, biomass energy has broad application prospects through biological, chemical, and thermochemical conversion technologies. Lignocellulosic biomass, a renewable, non-food organic material whose main components include cellulose, hemicellulose, and lignin, holds great potential for the sustainable production of liquid fuels and chemicals.

[0003] The complexity of wood fiber structure limits the high-value utilization of all components of lignocellulosic biomass. Traditional biorefining focuses on the separation, purification, conversion, and utilization of carbohydrates. However, due to harsh reaction conditions, native lignin readily undergoes polycondensation, forming chemically stubborn and difficult-to-convert industrial lignin, which often must be burned as waste. There is an urgent need to develop biorefining methods that can fully utilize the value of all components of lignocellulosic biomass. Summary of the Invention

[0004] In response to the above problems, the present invention provides a method for the graded utilization of biomass based on lignin priority, which can effectively inhibit the condensation reaction between lignin macromolecules and significantly reduce the difficulty of subsequent conversion of lignin and its derivatives. Lignin and its derivatives are catalytically converted to obtain hydrocarbon compounds, and the solid residues are used to prepare bioalcohol through saccharification and fermentation, thereby realizing the full component utilization of lignocellulosic biomass.

[0005] The present invention provides a biomass hierarchical utilization method based on lignin priority, comprising the following steps:

[0006] Lignin component preferential separation step: pre-treating lignocellulosic biomass to obtain solid residue, lignin and its derivatives;

[0007] Lignin and its derivatives catalytic conversion step: using catalytic thermochemical conversion technology to convert lignin and its derivatives into hydrocarbon compounds through a one-step or two-step process;

[0008] In the solid residue enzymatic hydrolysis and fermentation step, the solid residue produced in the lignin component preferential separation step is subjected to saccharification and fermentation to obtain bioalcohol, wherein the solid residue comprises cellulose and hemicellulose.

[0009] According to the technical solution, the biomass graded utilization method based on the preferential separation of lignin can effectively inhibit the condensation reaction between lignin macromolecules and significantly reduce the difficulty of subsequent conversion of lignin and its derivatives; lignin and its derivatives are catalytically converted into hydrocarbon compounds, thereby improving the utilization value of lignocellulosic biomass; the solid residue does not participate in the reaction in the preferential separation step of the lignin component, thereby reducing the difficulty of lignin separation, and the lignin content in the residue after separation of the lignin component is reduced, and in the subsequent saccharification and fermentation steps, the ineffective adsorption of lignin components on cellulase is reduced, which is conducive to the saccharification and fermentation of the solid residue to prepare high-yield bioalcohol, further improving the full component conversion and utilization efficiency of forestry biomass resources with high lignin content; it should be noted that catalytic thermochemical conversion technology refers to the combination of catalyst and thermochemical conversion. Thermochemical conversion refers to the thermal conversion of fuel, which is the main technical approach to utilizing hydrocarbon-based fuels such as coal, oil, natural gas, biomass, and organic waste. It is manifested in different conversion processes such as combustion, gasification, pyrolysis / carbonization, reforming / cracking, and reduction / oxidation depolymerization.

[0010] In an optional technical solution of the present invention, in the step of preferentially separating the lignin components, pretreating the lignocellulosic biomass comprises:

[0011] The lignin preferential fractionation and depolymerization step includes: adding lignocellulosic biomass, an organic solvent, and a catalyst into a reaction vessel, and controlling the reaction vessel to a specified temperature and a specified pressure; the lignocellulosic biomass is catalytically reduced and depolymerized under the action of the catalyst to obtain a pretreatment liquid and a solid residue; the pretreatment liquid is concentrated to obtain a lignin-derived phenolic platform compound, which is an oxygen-containing aromatic monomer compound.

[0012] According to this technical solution, the reaction solvent system is single and therefore easier to recycle and reuse; at the same time, depolymerization and fractionation can occur simultaneously in the same reaction vessel, and its operation process is simpler and more convenient than traditional distillation technology; in addition, there is no need to use dilute acid as an auxiliary, and the process is safer and more environmentally friendly.

[0013] In an optional technical solution of the present invention, in the step of preferentially separating the lignin components, the catalyst used is one or more of NiMo / Al2O3, Ni / Al2O3, and Mo / Al2O3, the catalyst loading is 3-9wt%, and the amount of catalyst input is 0.05-0.15 times the initial mass of the lignocellulosic biomass, the specified temperature is 200-275°C, and the specified pressure is 0-4MPa.

[0014] According to this technical solution, under the parameters of temperature, pressure, catalyst type, catalyst loading, and catalyst input, lignin biomass is directly catalytically depolymerized and converted into lignin-derived phenol platform compounds and solid residues. The conversion difficulty is low, and the lignin-derived phenol platform compounds have a high yield and high selectivity.

[0015] In an optional technical solution of the present invention, in the step of preferentially separating the lignin components, pretreating the lignocellulosic biomass comprises:

[0016] Extraction step: adding lignocellulosic biomass, dilute acid and low-boiling-point organic solvent into a reaction vessel for extraction, and controlling the temperature and pressure in the reaction vessel to obtain a liquid phase containing lignin and its derivatives and a solid residue;

[0017] Solid residue washing step: using a low-boiling point organic solvent to wash the solid residue to remove the lignin and its derivatives remaining on the surface of the solid residue;

[0018] Lignin recovery step: the liquid phase containing lignin and its derivatives is mixed with the washing liquid in the solid residue washing step and concentrated by rotary evaporation, precipitated by adding ice deionized water, and filtered to obtain a precipitate, which is the extracted organic solvent lignin.

[0019] According to this technical solution, lignocellulosic biomass can be dissolved in a low-boiling point organic solvent, and high-activity lignin and its derivatives can be extracted with high yield by a dilute acid-assisted organic solvent method, separating the pretreatment step and the catalytic conversion step of lignin and its derivatives, which is more flexible; lignin and its derivatives are obtained by acid-assisted organic solvent extraction, which has better controllability for the distribution of target products, and can achieve a higher yield of lignin raw materials to phenol platform compounds by applying a regulatory strategy. Then, starting from the phenol monomer platform compound, by optimizing the reaction system and changing the catalytic strategy, different purposes of hydrodeoxygenation production of aromatic hydrocarbon products or cycloalkane products can be achieved. By washing the solid residue with a low-boiling point organic solvent, the yield of the lignin component can be increased, and the utilization rate of the whole cellulose can be increased while achieving lignin refining. The washing of the solid residue reduces the content of the lignin component in the solid residue, reduces the ineffective adsorption of cellulase by the lignin component, and is conducive to the subsequent saccharification and fermentation, thereby increasing the yield of bio-alcohol. Furthermore, low-boiling-point organic solvents offer advantages such as low cost, environmental friendliness, short raw material processing time, easy recycling, and a simple process. Furthermore, low-boiling-point organic solvents stabilize carbocation intermediates during extraction. For example, methanol, as a strong nucleophile, can protect the benzyl carbocation formed at the α-position of β-O-4 during pretreatment, thereby preventing lignin from undergoing further condensation reactions to a certain extent through etherification. This protocol also maintains system pressure by purging nitrogen, providing enhanced safety.

[0020] In an optional technical solution of the present invention, in the extraction step, the temperature in the reaction vessel is 120-180° C., the pressure is 0-4 MPa, and the low-boiling-point organic solvent includes methanol, ethanol or acetone.

[0021] According to this technical solution, under the temperature and pressure conditions, the use of low-boiling-point organic solvents to extract lignin and its derivatives has a better extraction effect, which is conducive to promoting the separation of lignin components; the use of low-boiling-point organic solvents such as methanol, ethanol, and acetone with a boiling point below 100°C has a wide range of raw material sources, is easy to obtain, has low cost, is environmentally friendly, and has a short processing time.

[0022] In an optional technical solution of the present invention, in the catalytic conversion step of lignin and its derivatives, lignin and its derivatives are converted into hydrocarbon compounds through a one-step process comprising:

[0023] Under a low-pressure nitrogen atmosphere, the organic solvent lignin separated in the lignin component preferential separation step is converted into hydrocarbon compounds through catalytic pyrolysis in a one-step process; wherein the catalytic pyrolysis is carried out under a hydrogen pressure of 0-4 MPa, the catalyst used is one or more of NiMo / Al2O3, Ni / Al2O3, and Mo / Al2O3, and the reaction temperature is 300-500°C.

[0024] According to this technical solution, organic solvent lignin can be converted into hydrocarbon compounds in one step through catalytic thermal decomposition. The conversion difficulty is low, the preparation process of hydrocarbon compounds is shortened, the preparation efficiency is improved, the reaction time is short, the raw material processing volume is large, and continuous production is easy to achieve, which is conducive to cost savings. In this solution, the organic solvent lignin is fed in solid form and no organic solvent is used, avoiding the energy consumption of solvent recovery; in addition, the organic solvent lignin is converted into alkane and aromatic hydrocarbon products through carbon chain growth (aldol condensation, coupling reaction, and alkylation occur under the induction of the catalyst to increase the carbon chain) combined with hydrodeoxygenation reaction, decarboxylation and decarbonylation reaction.

[0025] In an optional technical solution of the present invention, in the catalytic conversion step of lignin and its derivatives, lignin and its derivatives are converted into hydrocarbon compounds through a one-step process comprising:

[0026] The lignin-derived phenol platform compound separated in the lignin component priority separation step is added to a reactor and subjected to catalytic hydrogenation reduction to obtain a hydrocarbon compound.

[0027] According to this technical solution, hydrocarbon compounds are obtained by catalytically hydrogenating and reducing lignin-derived phenol platform compounds. The conversion difficulty is low, and by controlling parameters such as hydrogen pressure and reaction time, hydrocarbon compounds rich in aviation fuel are obtained, which have high utilization value. The generation of lignin-derived phenol platform compounds occurs in a liquid phase system, which improves the flexibility of preparation.

[0028] In an optional technical solution of the present invention, in the catalytic conversion step of lignin and its derivatives, lignin and its derivatives are converted into hydrocarbon compounds through a two-step process comprising:

[0029] Depolymerization step: Under a low-pressure nitrogen atmosphere, the organic solvent lignin is depolymerized under the catalytic action of NiMo / Al2O3, Ni / Al2O3 or Mo / Al2O3 to form a lignin-derived phenol platform compound, which is an oxygen-containing aromatic monomer compound;

[0030] Catalytic step: adding the lignin-derived phenol platform compound into the reactor for catalytic hydrogenation reduction to obtain hydrocarbon compounds.

[0031] According to the technical solution, organic solvent lignin can obtain hydrocarbon compounds by depolymerization and catalysis in a liquid phase system, and the conversion difficulty is low. By first converting lignin biomass into organic solvent lignin, and then converting it into a lignin-derived phenol platform compound through organic solvent lignin, the distribution of the target product has better controllability, and the higher yield and high selectivity of lignin raw material to lignin-derived phenol platform compound can be achieved by regulation. Then, starting from the lignin-derived phenol platform compound, the hydrodeoxygenation production is achieved by optimizing the reaction system and changing the catalytic strategy to produce aromatic products or cycloalkane products, which is conducive to improving the yield and quality of alkane products. Using the above-mentioned catalyst has a better catalytic effect, which is conducive to improving the catalytic conversion efficiency of lignin and its derivatives. In the depolymerization step, the weakly acidic alumina carrier can promote acid-catalyzed benzyl alkylation (Alkylation) and ether exchange (Transetherification), thereby suppressing the condensation reaction of lignin, improving product quality, and being conducive to realizing the high-value reuse of the product; and under a nitrogen atmosphere, the safety of the catalysis can be guaranteed.

[0032] In an optional technical solution of the present invention, in the catalytic conversion step of lignin and its derivatives,

[0033] The catalytic hydrogenation reduction reaction of lignin-derived phenol platform compounds occurs in water or n-hexane solvent and is carried out at a pressure of 0-4 MPa. Hydrogen or alcohol in-situ hydrogen donors are used to provide the active hydrogen required for the reduction reaction. The catalyst used is Ru / Nb2O5, the metal loading of the catalyst is 1-6%, and the reaction temperature is 220-280°C.

[0034] According to this technical solution, a Ru / Nb2O5 catalyst is used, and the metal loading of the catalyst is controlled to be 1-6%, and the catalytic temperature of the catalyst is 220-280°C, which can have a better catalytic effect and accelerate the efficiency of the reduction reaction. A hydrogen atmosphere of 0-4MPa is used to ensure the amount of hydrogen used for catalytic hydrogenation reduction, ensure the smooth progress of the catalytic reduction reaction, and improve the yield of the product hydrocarbon compounds.

[0035] In an optional technical solution of the present invention, bio-alcohol is produced from the solid residue through stepwise saccharification and fermentation. Prior to the enzymatic hydrolysis and fermentation step of the solid residue, the process further includes adjusting the pH of the solid residue enzymatic hydrolysis and fermentation system to 4.8-5.2. This stepwise saccharification and fermentation process optimizes the maximum productivity of each strain at different stages (by performing the saccharification and fermentation stages separately, the temperature and pH of each stage can be controlled to achieve optimal temperatures and pH values for each). This ensures the efficient operation of the amylase used in the saccharification and fermentation process, ensuring saccharification and fermentation results, and increasing the saccharification rate and bio-alcohol yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the process of the biomass graded utilization of lignin in an embodiment of the present invention.

[0037] Figure 2 Schematic diagram of a specific process of the method for fractionated utilization of lignin in accordance with an embodiment of the present invention.

[0038] Figure 3 Schematic diagram of the process of the biomass fractionation utilization method of lignin in Test Example 1 in an embodiment of the present invention.

[0039] Figure 4 Schematic diagram of the process of the biomass graded utilization method of lignin in Test Example 2 in an embodiment of the present invention.

[0040] Figure 5 Schematic diagram of the process of biomass graded utilization of lignin in Test Example 3 in an embodiment of the present invention.

[0041] Figure 6 This is a gas chromatography-mass spectrometry (GC / MS) spectrum of the product of Example 1 in an embodiment of the present invention.

[0042] Figure 7 This is a gas chromatography-mass spectrometry (GC / MS) spectrum of the product of Example 2 in an embodiment of the present invention.

[0043] Figure 8 This is a gas chromatography-mass spectrometry (GC / MS) spectrum of the product of Example 3 in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] like Figure 1 、 Figure 2 As shown, the present invention provides a biomass graded utilization method based on lignin priority, comprising the following steps:

[0046] S1: Lignin component preferential separation step: pre-treating lignocellulosic biomass to obtain solid residue, lignin and its derivatives;

[0047] S2: catalytic conversion of lignin and its derivatives: using catalytic thermochemical conversion technology, lignin and its derivatives are converted into hydrocarbon compounds through a one-step or two-step process (hydrocarbon compounds mainly refer to hydrocarbon fuels rich in aviation fuel (including aviation kerosene and aviation gasoline, the main components of which are C8-C16 aromatics and alkanes) with high added value);

[0048] S3: solid residue enzymatic hydrolysis and fermentation step, the solid residue produced in the lignin component preferential separation step is saccharified and fermented step by step to obtain bioalcohol (such as bioethanol, butanol, etc.), and the solid residue is cellulose and hemicellulose.

[0049] The biomass graded utilization method based on the preferential separation of lignin can effectively inhibit the condensation reaction between lignin macromolecules and significantly reduce the difficulty of subsequent conversion of lignin and its derivatives. Lignin and its derivatives are catalytically converted into hydrocarbon compounds, thereby improving the utilization value of lignocellulosic biomass. The solid residue does not participate in the reaction in the preferential separation step of the lignin component, which reduces the difficulty of lignin separation, and the lignin content in the residue after the lignin component is separated is reduced. In the subsequent saccharification and fermentation steps, the ineffective adsorption of cellulase by the lignin component is reduced, which is conducive to the saccharification and fermentation of the solid residue to prepare high-yield bioalcohol, further improving the conversion and utilization efficiency of all components of forestry biomass resources with high lignin content.

[0050] In order to verify the effectiveness of the lignin-first biomass fractionation utilization method provided by this embodiment, the following tests were conducted in this embodiment:

[0051] Test Example 1

[0052] Test Example 1 Figure 3The pathway shown in the figure uses poplar wood flour as the raw material for preparing lignin-derived phenolic platform compounds. Specifically, lignin undergoes preferential catalytic reductive depolymerization: poplar wood flour, a low-boiling-point organic solvent, and a catalyst are added to a reactor, with a liquid-to-solid ratio of the low-boiling-point organic solvent to the poplar wood flour of 10-30. The NiMo / Al2O3 catalyst used has a metal loading of 3-9 wt%, and the catalyst input is 0.1 times the initial biomass mass.

[0053] The reactor was sealed, and the atmosphere was replaced three times under stirring, followed by filling with 3 MPa nitrogen. The temperature was raised to 250°C by electric heating and maintained for 3 hours. The poplar wood powder underwent catalytic reduction depolymerization under the action of the catalyst.

[0054] After the reaction is completed, solid-liquid separation is performed through a funnel to obtain a pretreated liquid and a solid residue. The pretreated liquid is concentrated to obtain lignin oil enriched in phenol monomers (i.e., phenol oil, lignin-derived phenol platform compounds), which has high application value.

[0055] In addition, this example also changes the type of catalyst to carry out the above experiment to prepare a variety of lignin-derived phenol platform compound products, as shown in the following Table 1-1:

[0056] Table 1-1 Comparative Examples of Catalysts for Reduction Catalytic Fractionation Process

[0057]

[0058] According to Table 1-1, the total peak area of the lignin-derived phenol platform compounds prepared by NiMo / Al2O3 as a catalyst is significantly higher than the total peak area of the lignin-derived phenol platform compounds prepared by other types of catalysts, that is, NiMo / Al2O3 as a catalyst has a better catalytic effect on the depolymerization of lignocellulosic biomass, and the yield of the obtained lignin-derived phenol platform compounds is higher.

[0059] Test Example 2

[0060] Test Example 2 Figure 4 The pathway shown uses poplar sawdust as lignin biomass as raw material and three different organic solvents (methanol / water, ethanol / water, and acetone / water) to prepare organic solvent lignin corresponding to the three organic solvents using the same method (lignin in biomass is soluble in organic solvents under certain conditions, and lignin recovered from the liquid fraction is called organic solvent lignin). The following method is uniformly described using organic solvents.

[0061] <Acid-assisted organic solvent extraction of lignin components>

[0062] Poplar sawdust is added to the reaction vessel, and the liquid phase consists of an organic solvent and a dilute H2SO4 solution.

[0063] The reactor was sealed, and the atmosphere was replaced three times under stirring, followed by filling with 3 MPa nitrogen. The temperature was raised to 160°C by electric heating and maintained for 30 minutes. The poplar sawdust was extracted in a mixed solution of organic solvent and dilute H2SO4 solution.

[0064] After the extraction, the liquid phase containing the extracted lignin components was separated from the solid portion by filtration, and the solid residue obtained by filtration was washed with an amount of organic solvent three times that used for extraction to remove any residual lignin and its derivatives on the surface.

[0065] The filtrate and washings were combined and concentrated by rotary evaporation. Ice-cold deionized water was then added to precipitate the lignin and its derivatives. The precipitated lignin and its derivatives were separated by filtration and then vacuum-dried overnight to obtain three organic solvent-based poplar lignins. Table 2-1 below shows the extraction yields of the three organic solvent-based poplar lignins.

[0066] Table 2-1 Comparative Examples of Solvents in Organic Solvent Fractionation Process

[0067]

[0068] In addition, in this test example, organic solvent lignin was also catalytically depolymerized to obtain a lignin-derived phenol platform compound. Specifically, the catalytic depolymerization of organic solvent lignin was carried out in a high-pressure reactor, and organic solvent lignin and NiMo / Al2O3 catalyst were added. The catalyst input amount was 0.5 times the mass of the organic solvent lignin, and anhydrous ethanol was used as the solvent.

[0069] After sealing the reactor, it was purged with N2 three times under stirring and then filled with normal pressure N2; the reactor was heated to 280°C and the reaction was maintained for 12 hours.

[0070] After the reaction is completed, the reactor is cooled to room temperature; the liquid phase and the solid residue are separated by a centrifuge, and then the solid residue is washed with additional ethanol solvent. All the liquid phase products after washing are collected and concentrated by rotary evaporation and fixed to the target volume.

[0071] The products were quantified using the external standard method. In this example, phenol, guaiacol, 4-ethylphenol, 4-ethyl-guaiacol, 4-ethoxyphenol, vanillin, 2,6-dimethoxyphenol, dihydroeugenol, syringaldehyde, 2-tert-butyl-6-methylphenol, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, and 2,6-di-tert-butyl-4-ethylphenol were selected as standard substances. Table 2-2 below shows the total yield of aromatic monomers from the catalytic depolymerization of lignin using different organic solvents.

[0072] Table 2-2 Comparative examples of lignin catalytic depolymerization with different organic solvents

[0073]

[0074] a The total yield of aromatic monomers = the ratio of the total mass of the target aromatic monomer compound to the mass of the initial organic solvent lignin; the aromatic monomers in this embodiment are lignin-derived phenol platform compounds.

[0075] In this embodiment, poplar lignin was extracted by methanol under the auxiliary catalysis of dilute sulfuric acid, and the extraction efficiency was 51.2%. The separated organic solvent lignin was depolymerized by NiMo / Al2O3 catalyst under a nitrogen atmosphere at normal pressure, and the total yield of aromatic monomers was 35.64%. The total yield of aromatic monomers obtained by extracting poplar lignin with methanol as the organic solvent and depolymerizing the poplar lignin was better.

[0076] In this test example, the organic solvent played a role in stabilizing the carbonium ion intermediate during the extraction process. For example, methanol, as a strong nucleophile, protected the benzyl carbonium ion formed at the α-position of β-O-4 during the pretreatment process (as shown in the reaction equation below, the left side shows the benzyl carbonium ion before stabilization in the organic solvent lignin, and the right side shows the carbonium ion intermediate after stabilization). This, in turn, prevented the re-condensation reaction of lignin to a certain extent through etherification.

[0077]

[0078] The weakly acidic alumina support can promote acid-catalyzed benzylic alkylation and transetherification (as shown in the following reaction formula, where DME is demethylation, DMO is demethoxylation, and DDO is direct deoxygenation), thereby inhibiting the condensation reaction between lignin molecules.

[0079]

[0080] Test Example 3:

[0081] by Figure 5 Taking the pathway in the process as an example, a phenolic platform compound and a Ru / Nb2O5 catalyst are added to the reactor, and the hydrodeoxygenation of the lignin-derived phenolic platform compound is carried out in water or n-hexane solvent.

[0082] The reactor is sealed, the atmosphere replaced three times with stirring, and then filled with gas at a constant pressure. The temperature is raised to a desired level by electrical heating and maintained for 12 hours (specifically, 250°C, water as the solvent, nitrogen atmosphere, and methanol as the hydrogen donor). Hydrodeoxygenation of the phenolic platform compounds occurs to produce aromatic and alkane products. Furthermore, depolymerization (of lignocellulosic biomass or organic solvent lignin) coupled with hydrodeoxygenation allows the degree of aromatic ring hydrogenation to be controlled by adjusting the reaction conditions (reaction time and hydrogen pressure), resulting in the selective production of aromatic and cycloalkane products.

[0083] After the reaction, the liquid phase containing the extracted lignin was separated from the solid phase by filtration. The products were qualitatively and quantitatively analyzed by GC / MS. Toluene, ethylbenzene, propylbenzene, methylcyclohexane, ethylcyclohexane, propylcyclohexane, 1,3,5-trimethylcyclohexane, and bicyclohexane were selected as standard substances.

[0084] Significant hydrogenolysis and dehydrogenation-decarbonylation reactions occur during the hydrodeoxygenation process. Controlling the hydrogen pressure can ensure that the hydrodeoxygenation products are exclusively alkanes. Adding a hydrogen donor solvent or using low hydrogen pressure can inhibit excessive hydrogenation of aromatic rings and reduce external hydrogen consumption, thereby improving the selectivity of aromatic products. In some embodiments, in-situ hydrogen donors such as methanol, ethanol, and isopropanol can be used.

[0085] Table 3-1 Comparative Example of Hydrogen Pressure in Hydrodeoxygenation of Lignin-derived Phenolic Platform Compounds

[0086]

[0087] b Reaction conditions: reaction temperature is 250℃, water is used as solvent; c Nitrogen atmosphere, methanol as hydrogen supply.

[0088] Example 1

[0089] The steps of Test Example 1 were repeated to obtain a lignin-derived phenol platform compound. Figure 6 This is the GC / MS spectrum of the lignin-derived phenol platform compounds prepared using NiMo / Al2O3 as the catalyst in Example 1. The selectivities for phenol, 2-methoxyphenol, 2-methoxy-4-ethylphenol, 2,6-dimethoxyphenol, trans-isoeugenol, 5-tert-butylpyrogallol, and methyl parahydroxybenzoate all exceeded 5%, indicating that the products were concentrated in these compounds.

[0090] The resulting lignin-derived phenolic platform compounds were subjected to catalytic hydrodeoxygenation. Specifically, the lignin oil was reacted over a Ru / Nb2O5 catalyst (metal loading of 1-6 wt% at a reaction temperature of 220-280°C) using n-hexane as the solvent under optimal conditions of 2 MPa hydrogen for 12 hours, yielding 75.29% of the resulting alkanes.

[0091] The solid residue after preferential separation of lignin is mainly cellulose and hemicellulose components, which are converted into ethanol through step-by-step saccharification and fermentation. The pH of the system is first adjusted to 4.8-5.0, and then Novozymes Ctec3 cellulase is added and placed in a shaker (50°C, 200 rpm, 48 hours) for saccharification. The supernatant after centrifugation is the required enzymatic hydrolysate. The enzymatic hydrolysate is mixed with yeast powder and peptone in an oxygen-limited bottle to obtain a fermentation hydrolysate. Finally, yeast is inoculated for fermentation (32°C, pH = 5). The saccharification rate is 67.57% and the ethanol yield is 0.427g / g monosaccharide.

[0092] Example 2

[0093] Repeat the steps of Test Example 2 to obtain a lignin-derived phenol platform compound. Figure 7 The GC / MS spectrum of the lignin-derived phenol platform compound prepared in Test Example 2 using NiMo / Al2O3 as a catalyst and methanol as an organic solvent is shown in the figure. In addition to phenol, guaiacol, 2,6-dimethoxyphenol, and dihydroeugenol, the product is also rich in C12 + of alkylphenols.

[0094] Lignin-derived phenolic platform compounds (aromatic monomers) obtained by catalytic depolymerization using n-hexane as a solvent and methanol as an organic solvent are reacted over a Ru / Nb2O5 catalyst (metal loading of 1-6 wt% and reaction temperature of 220-280°C) under preferably 2 MPa hydrogen conditions for 12 hours, yielding 63.47% of the resulting alkanes. Preferably, an in-situ hydrogen donor such as methanol, ethanol, or isopropanol is used during the catalytic hydrodeoxygenation process to provide the hydrogen required for reduction.

[0095] The solid residue after preferential separation of lignin is mainly cellulose and hemicellulose components, which are converted into ethanol through step-by-step saccharification and fermentation. The pH of the system is first adjusted to 4.8-5.0, and then Novozymes Ctec3 cellulase is added and placed in a shaker (50°C, 200 rpm, 36 hours) for saccharification. The enzymatic hydrolysate is mixed with yeast powder and peptone in an oxygen-limited bottle and then inoculated with yeast for fermentation (32°C, pH = 5). The saccharification rate is 76.63% and the ethanol yield is 0.42g / g monosaccharide.

[0096] Example 3:

[0097] Repeat the steps of Test Example 2 to obtain organic solvent lignin extracted with methanol. The organic solvent lignin was converted into hydrocarbon compounds by NiMo / Al2O3 catalytic pyrolysis under a 1 MPa hydrogen atmosphere. The reaction temperature was 300-500°C, and the mass ratio of catalyst to organic solvent lignin was 10:1. The results were analyzed online using GC-MS. Figure 8 As shown, the selectivity of the target product is 98.33%, mainly including C14 + of chain alkanes, pentamethylbenzene, hexamethylbenzene, 2,4-dimethylstyrene and naphthalene series.

[0098] The solid residue after preferential separation of the lignin component is mainly cellulose and hemicellulose components, which are converted into ethanol through step-by-step saccharification and fermentation. The pH of the system is first adjusted to 4.8-5.0, and then Novozymes Ctec3 cellulase is added and placed in a shaker (50°C, 200 rpm, 36 hours) for saccharification. The enzymatic hydrolysate is mixed with yeast powder and peptone in an oxygen-limited bottle and then inoculated with yeast for fermentation (32°C, pH = 5). The saccharification rate is 76.63% and the ethanol yield is 0.42g / g monosaccharide.

[0099] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A biomass graded utilization method based on lignin priority, characterized in that: The following steps are involved: Lignin component preferential separation step: pre-treating the lignocellulosic biomass to obtain solid residues, lignin and its derivatives, wherein the lignocellulosic biomass is pre-treated by catalytic depolymerization or extraction, and the lignin component preferential separation step includes a lignin preferential fractionation depolymerization step or an extraction step: The lignin preferential fractionation and depolymerization step comprises: adding the lignocellulosic biomass, an organic solvent, and a catalyst into a reaction vessel, and controlling the reaction vessel to a specified temperature and a specified pressure, wherein the lignocellulosic biomass is catalytically reduced and depolymerized under the action of the catalyst to obtain a pretreated liquid and a solid residue; in the lignin component preferential separation step, the catalyst used is one or more of NiMo / Al2O3, Ni / Al2O3, and Mo / Al2O3, the catalyst loading is 3-9 wt%, and the catalyst input amount is 0.05-0.15 times the initial mass of the lignocellulosic biomass; the specified temperature is 200-275°C, and the specified pressure is 0-4 MPa; The extraction step comprises: adding the lignocellulosic biomass, dilute acid, and a low-boiling-point organic solvent into a reaction vessel for extraction, and controlling the temperature and pressure in the reaction vessel to obtain a liquid phase containing lignin and its derivatives and a solid residue, wherein the temperature in the reaction vessel is 120-180° C. and the pressure is 0-4 MPa, and the low-boiling-point organic solvent includes methanol, ethanol, or acetone; Lignin and its derivatives catalytic conversion step: using catalytic thermochemical conversion technology to convert the lignin and its derivatives into hydrocarbon compounds through a one-step or two-step process; a solid residue enzymatic hydrolysis and fermentation step, wherein the solid residue produced in the lignin component preferential separation step is subjected to saccharification and fermentation to obtain bioalcohol, wherein the solid residue comprises cellulose and hemicellulose; In the catalytic conversion step of lignin and its derivatives, the lignin and its derivatives are converted into hydrocarbon compounds through a one-step process comprising: The organic solvent lignin separated in the lignin component preferential separation step is catalytically pyrolyzed in the presence of a catalyst to be converted into hydrocarbon compounds in one step; wherein the catalytic pyrolysis is carried out under a hydrogen pressure of 0-4 MPa, the catalyst used is one or more of NiMo / Al2O3, Ni / Al2O3, Mo / Al2O3, and the reaction temperature is 300-500°C; or, In the catalytic conversion step of lignin and its derivatives, the lignin and its derivatives are converted into hydrocarbon compounds through a two-step process including: Depolymerization step: under a low-pressure nitrogen atmosphere, the organic solvent lignin is depolymerized under the catalytic action of NiMo / Al2O3, Ni / Al2O3 or Mo / Al2O3 to form a lignin-derived phenol platform compound, wherein the lignin-derived phenol platform compound is an oxygen-containing aromatic monomer compound; Catalytic step: adding the lignin-derived phenol platform compound into a reactor for catalytic hydrogenation reduction to obtain hydrocarbon compounds.

2. The method for biomass fractionation and utilization based on lignin priority according to claim 1, characterized in that: The pretreatment liquid is concentrated to obtain a lignin-derived phenol platform compound, which is an oxygen-containing aromatic monomer compound.

3. The method for biomass fractionation and utilization based on lignin priority according to claim 1, characterized in that: In the step of preferentially separating the lignin components, pretreating the lignocellulosic biomass comprises: Solid residue washing step: washing the solid residue with the low boiling point organic solvent to remove the lignin and its derivatives remaining on the surface of the solid residue; Lignin recovery step: the liquid phase containing lignin and its derivatives is mixed with the washing liquid in the solid residue washing step, concentrated by rotary evaporation, precipitated by adding ice deionized water, and filtered to obtain a precipitate of lignin and its derivatives, wherein the precipitate of lignin derivatives is an organic solvent lignin.

4. The method for biomass fractionation and utilization based on lignin priority according to claim 2, characterized in that: In the catalytic conversion step of lignin and its derivatives, converting the lignin and its derivatives into hydrocarbon compounds through a one-step process includes: The lignin-derived phenol platform compound separated in the lignin component preferential separation step is added to a reactor and subjected to catalytic hydrogenation reduction to obtain a hydrocarbon compound.

5. The method for biomass fractionation and utilization based on lignin priority according to claim 4, characterized in that: In the catalytic conversion step of lignin and its derivatives, The catalytic hydrogenation reduction reaction of the lignin-derived phenol platform compound occurs in water or n-hexane solvent and is carried out at a pressure of 0-4 MPa. Hydrogen or an alcohol in-situ hydrogen donor is used to provide the active hydrogen required for the reduction reaction. The catalyst used is Ru / Nb2O5, the metal loading of the catalyst is 1-6%, and the reaction temperature is 220-280°C.

6. The method for biomass fractionation and utilization based on lignin priority according to claim 1, characterized in that: The solid residue is subjected to stepwise saccharification and fermentation to obtain the bio-alcohol, and before the solid residue enzymatic hydrolysis and fermentation step, the method further comprises: adjusting the pH of the solid residue enzymatic hydrolysis and fermentation system to 4.8-5.2.

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