High-stability green fuel oil and preparation method thereof

Abstract

The invention discloses high-stability green fuel oil and a preparation method thereof, and relates to the technical field of green energy preparation. The invention relates to a preparation method of high-stability green fuel oil, which comprises the following steps: crushing a biomass raw material, adopting a water-isopropanol cosolvent as a reaction medium, adding a lithium-containing catalyst, heating, and carrying out liquefaction reaction to obtain a liquefied product; filtering the liquefied product, extracting, and distilling to obtain a fuel oil precursor; adding a hydrogen donor, a hydrogenation catalyst and methanol into the fuel oil precursor, and carrying out a hydrodeoxygenation reaction under the assistance of a plasma electrolysis method to obtain a reaction product; and carrying out centrifugal separation and distillation on the reaction product to obtain the green fuel oil. According to the method, the reaction efficiency is greatly improved, excessive condensation of reaction products is avoided, the content of oxygen-containing compounds is reduced, the calorific value is remarkably increased, and therefore the high-stability and high-quality green fuel oil is obtained.

Description

Technical Field

[0001] This application relates to the technical field of green energy preparation, and particularly relates to a highly stable green fuel and a preparation method thereof. Background Art

[0002] With the development of society, the demand for liquid energy by humans is increasing. Currently, fossil fuels such as coal, oil, and natural gas are still the main energy sources for the normal operation and development of human society. However, the existing reserves of fossil fuels are limited, and the use of fossil fuels will also emit a large amount of carbon dioxide and some toxic gases into the air. Green fuel mainly refers to fuel produced through renewable resources or environmentally friendly processes, which has the characteristics of low carbon emissions, renewability, and environmental friendliness, and can be used as a supplementary energy source for fossil fuels to optimize the energy structure. Biomass is a carrier for storing biomass energy, with a wide variety and rich reserves. It is also the fourth largest energy source after coal, oil, and natural gas, and is a very important part of the energy structure. Biomass refers to various organisms formed through photosynthesis, including all plants, microorganisms, and animal excreta. It has the advantages of renewability, low pollution, wide distribution, carbon neutrality, and low sulfur and nitrogen content. Converting biomass into liquid energy through chemical methods to produce green fuel that can be used as a substitute for petroleum diesel is conducive to promoting energy substitution, reducing environmental pressure, and controlling urban air pollution.

[0003] However, in the process of biomass conversion, the reaction time is usually long, the reaction efficiency is low, and the liquid product further undergoes a polymerization reaction at high temperature, resulting in the instability of the obtained liquid product, and the oxygen content is usually high, resulting in a low calorific value. The higher heating value is usually lower than 20 MJ / kg. The instability of the product and the high oxygen content limit the application of green fuel. Summary of the Invention

[0004] The main purpose of this application is to provide a highly stable green fuel and a preparation method thereof, aiming to solve the technical problems of high oxygen content and unstable products in existing biomass liquid conversion fuels.

[0005] To achieve the above object, this application provides a preparation method of a highly stable green fuel, including the following steps:

[0006] After crushing the biomass raw material, using water-isopropanol co-solvent as the reaction medium, adding a lithium-containing catalyst, and heating for liquefaction reaction to obtain a liquefied product;

[0007] Filter the liquefied product, and then perform extraction and distillation to obtain a fuel precursor;

[0008] A hydrogen donor, a hydrogenation catalyst, and methanol are added to the fuel precursor, and a hydrodeoxygenation reaction is assisted by plasma electrolysis to obtain a reaction product;

[0009] After centrifugal separation and distillation of the reaction product, green fuel is obtained.

[0010] Optionally, the step of crushing the biomass raw material, using a water-isopropanol co-solvent as a reaction medium, adding a lithium-containing catalyst, and heating to carry out a liquefaction reaction to obtain a liquefied product includes:

[0011] The biomass raw material is crushed to a particle size of 80 μm - 100 μm, and water and isopropanol are mixed at a volume ratio of 1:1 as the reaction medium;

[0012] The crushed biomass raw material, the reaction medium, and the lithium-containing catalyst are added together to a homogeneous reactor, sealed, and purged with N 2 evacuated, and then filled with N at 2 MPa 2 as the initial atmosphere, heated to 260°C - 300°C at a heating rate of 8°C / min - 12°C / min, held for 0.4 h - 0.6 h, and stirred while maintaining a rotation speed of 160 r / min - 180 r / min. After the reaction, it is cooled to room temperature within 10 min to obtain a liquefied product.

[0013] Optionally, the lithium-containing catalyst is lithium bromide, and the mass ratio of the biomass raw material to the lithium-containing catalyst is 10:(3 - 5).

[0014] Optionally, the step of filtering the liquefied product, then performing extraction and distillation to obtain a fuel precursor includes:

[0015] The liquefied product is vacuum filtered to obtain a filtrate;

[0016] Dichloromethane is used as an extraction solvent to extract the filtrate, and the aqueous phase and the solvent phase are separated;

[0017] The solvent phase is subjected to vacuum distillation at 35°C - 40°C to obtain a fuel precursor.

[0018] Optionally, in the step of adding a hydrogen donor, a hydrogenation catalyst, and methanol to the fuel precursor, the hydrogen donor is sodium borohydride;

[0019] The hydrogenation catalyst includes an active metal component and a zirconium diboride whisker - zeolite composite support, wherein the active metal component includes Mn, Cu, Co, W, and Mo.

[0020] Optionally, the loading amount of the active metal component in the hydrogenation catalyst is 15%-25%; wherein, the molar ratio of Cu / Co is 1:(0.8-1), the molar ratio of Mn / (Cu+Co) is (0.3-0.5):1, and the molar ratio of W / Mo is 1:1;

[0021] The mass ratio of zirconium diboride whiskers to molecular sieve in the zirconium diboride whisker-molecular sieve composite support is 1:(1-1.5).

[0022] Optionally, the preparation steps of the hydrogenation catalyst include:

[0023] Add cellulose ether and starch ether into water at 55°C-65°C. After holding for 0.8h-1.2h, add the molecular sieve, stir and mix evenly, then add it into a pelletizer for rolling treatment. After forming spherical particles, add the zirconium diboride whiskers and continue rolling treatment for 3h-6h to obtain a support precursor;

[0024] Dry the support precursor at 70°C-80°C for 8h-12h, and then calcine it at 500°C-600°C for 2h-4h to obtain a zirconium diboride whisker-molecular sieve composite support;

[0025] Dissolve the soluble salt of the active metal component in water to obtain an active component solution;

[0026] Immerse the zirconium diboride whisker-molecular sieve composite support in the active component solution, stir and mix evenly, then stand for 6h-10h, and then dry it at 100°C-120°C for 8h-12h, and then calcine it at 400°C-500°C for 2h-4h to obtain the hydrogenation catalyst.

[0027] Optionally, in the step of adding a hydrogen donor, a hydrogenation catalyst and methanol to the fuel precursor, the mass ratio of the fuel precursor, the hydrogen donor, the hydrogenation catalyst and the methanol is 1:(0.2-0.4):(0.6-0.8):(4-5).

[0028] Optionally, the step of using plasma electrolysis to assist in the hydrodeoxygenation reaction to obtain a reaction product includes:

[0029] Use a plasma electrolysis generator, set the voltage to 600V-650V, the duty cycle to 25%-30%, and the pulse frequency to 220Hz-250Hz. Carry out the hydrodeoxygenation reaction under plasma electrolysis conditions. After 3min-4min, the reaction ends to obtain a reaction product.

[0030] This application also proposes a highly stable green fuel obtained by using the preparation method of the above highly stable green fuel.

[0031] The present application has at least the following beneficial effects:

[0032] First, the biomass raw material is liquefied in the present application. A water-isopropanol co-solvent is used as the reaction medium, and a lithium-containing catalyst is added to assist in catalysis. A large amount of H + and OH - are released by the ionization of water, causing the dielectric constant to drop sharply. As a result, the solubility of lipophilic hydrophobic organic substances such as lignin in water increases significantly. Moreover, isopropanol can be decomposed into acetone and active hydrogen, and the active hydrogen can promote the depolymerization and hydrogenation of biomass to reduce the oxygen content of the liquefied product, which is beneficial for the subsequent preparation of green fuel with a lower oxygen content. The acetone decomposed from isopropanol can undergo an aldol condensation reaction with aldehyde compounds generated by the hydrolysis of cellulose and hemicellulose to generate furan compounds, so as to increase the energy density of the liquefied product. Under the liquefaction system of the present application, cellulose and hemicellulose in the biomass raw material are mainly hydrolyzed to generate furfural, 2-furoic carboxaldehyde, 5-methyl-2-furoic carboxaldehyde, 2-hydroxy-2-cyclopentanone, etc., and further condense with acetone to generate furan compounds. Lignin is mainly hydrolyzed to generate 2-methoxyphenol, 2,6-dimethoxyphenol, etc., which together constitute the effective components of the fuel precursor;

[0033] The present application further performs hydrodeoxygenation treatment on the fuel precursor to reduce the oxygen element content and increase the calorific value, and introduces plasma electrolysis into the hydrodeoxygenation reaction. The plasma contains a large number of active particles such as electrons, ions, and free radicals. Driven by a strong electric field, these particles (·CHx, ·OH, ·H, etc.) can not only quickly heat the fuel precursor, but also accelerate the hydrogenation of the fuel precursor. Since the heat comes from the irregular thermal motion of the active particles, the heating process is more uniform and faster, and there is no temperature gradient and lag effect. The reaction time can be significantly shortened, and no additional heating is required. The reaction conditions are milder, avoiding the further polymerization reaction of some organic substances in the fuel precursor under long-term high-temperature heating, and significantly increasing the hydrocarbon compound content in the green fuel and greatly reducing the oxygen-containing compound content, resulting in a significant increase in the calorific value, thereby obtaining a green fuel with high stability and high quality. Its carbon chain length distribution is mainly C5-C18, which conforms to the carbon chain length for diesel fuel use and has the possibility of replacing some non-renewable energy sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0035] Figure 1 Flow chart of the preparation method of the highly stable green fuel described in the embodiments of the present application.

[0036] The realization of the purpose of the present application, functional features and advantages will be further described in conjunction with the embodiments with reference to the accompanying drawings. Specific embodiments

[0037] Next, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0038] In view of the technical problems existing in the prior art, the embodiments of the present application provide a preparation method of a highly stable green fuel, as Figure 1 shown, including the following steps:

[0039] S10. After crushing the biomass raw material, using a water-isopropanol co-solvent as the reaction medium, adding a lithium-containing catalyst, and heating for a liquefaction reaction to obtain a liquefied product.

[0040] The biomass raw material used in the present application is crop straw, herbaceous plants, woody plants or any mixture thereof, which is rich in cellulose, hemicellulose and lignin. During the liquefaction reaction, cellulose and hemicellulose in the biomass raw material are mainly hydrolyzed to produce water-soluble organic substances such as furfural, 2-furoic carboxaldehyde, 5-methyl-2-furoic carboxaldehyde and 2-hydroxy-2-cyclopentanone, and lignin is mainly hydrolyzed to produce phenolic compounds such as 2-methoxyphenol and 2,6-dimethoxyphenol.

[0041] In the specific implementation process, the biomass raw material is crushed to a particle size of 80 μm - 100 μm, and water and isopropanol are mixed at a volume ratio of 1:1 as the reaction medium;

[0042] The crushed biomass raw material, the reaction medium and the lithium-containing catalyst are added into a homogeneous reactor together. After sealing, N 2 is introduced for evacuation, and then N 2 at 2 MPa is charged as the initial atmosphere, and then heated to 260°C - 300°C at a heating rate of 8°C / min - 12°C / min, kept warm for 0.4 h - 0.6 h, and stirred at a rotation speed of 160 r / min - 180 r / min at the same time. After the reaction ends, it is cooled to room temperature within 10 min to obtain a liquefied product.

[0043] This application uses a water-isopropanol co-solvent as the reaction medium. Water can act as a non-polar solvent, making it the reaction medium for organic compounds. At the same time, when the water temperature rises to a certain condition, the ionization degree of water increases significantly, releasing more H + and OH - , causing the dielectric constant to drop sharply. As a result, the solubility of lipophilic hydrophobic organic substances such as lignin in water increases significantly, and they can even be miscible with oil. Due to the low viscosity and high solubility of hydrophobic organic substances, water can not only serve as the reaction medium but also has a catalytic effect. However, relying solely on the qualitatively changed water to liquefy and degrade biomass is very inefficient. Therefore, this application adds isopropanol as the reaction medium. Isopropanol itself is a good medium for organic reactions. With the assistance of reaction conditions and a lithium-containing catalyst, isopropanol can decompose into acetone and active hydrogen, and the active hydrogen can promote the depolymerization and hydrogenation of biomass to reduce the oxygen content of the liquefied product, which is beneficial for the subsequent preparation of green fuels with a lower oxygen content. The acetone decomposed from isopropanol can undergo an aldol condensation reaction with aldehyde compounds generated by the hydrolysis of cellulose and hemicellulose to form furan compounds. These compounds have advantages such as high energy density and high octane number and are organic substances that meet the requirements of gasoline, diesel, and aviation kerosene. At the same time, isopropanol can also act as a scavenger for reaction intermediates, such as phenolic and aldehyde compounds, inhibiting their repolymerization through reactions such as hydrogenation, alkylation, or esterification, thereby reducing the generation of coke by-products. As a result, this application obtains liquefied products with higher stability and quality under the reaction medium of the water-isopropanol co-solvent.

[0044] The lithium-containing catalyst used in this application is lithium bromide, and the mass ratio of the biomass raw material to the lithium-containing catalyst is 10:(3 - 5).

[0045] Since components such as cellulose, hemicellulose, and lignin in biomass are usually difficult to dissolve directly, but through the catalysis of lithium bromide, the solubility of these components can be increased, providing a better reaction matrix for the liquefaction reaction. In the water-isopropanol co-solvent system, lithium bromide can enhance the affinity between water and isopropanol, promote the dissolution of the reaction medium in biomass, and thus accelerate the reaction process. At the same time, as a strongly polar catalyst, lithium bromide can promote the charge transfer between molecules, change the polarity of the reaction medium, and promote the degradation of cellulose, hemicellulose, and lignin, causing them to break and generate monosaccharide structures such as glucose and xylose. The monosaccharide structures are unstable and continue to hydrolyze to form important furan compounds such as furfural with a furan ring.

[0046] S20. Filter the liquefied product, and then perform extraction and distillation to obtain a fuel precursor.

[0047] In the specific implementation process, vacuum filtration is performed on the liquefied product to obtain a filtrate;

[0048] Using dichloromethane as the extraction solvent, extract the filtrate to obtain an aqueous phase and a solvent phase;

[0049] Perform vacuum distillation on the solvent phase at 35°C - 40°C to remove dichloromethane, obtaining a fuel precursor.

[0050] S30. Add a hydrogen donor, a hydrotreating catalyst, and methanol to the fuel precursor, and use plasma electrolysis to assist in the hydrodeoxygenation reaction to obtain a reaction product.

[0051] Among them, the mass ratio of the fuel precursor, the hydrogen donor, the hydrotreating catalyst, and methanol is 1:(0.2 - 0.4):(0.6 - 0.8):(4 - 5).

[0052] In the specific implementation process, use a plasma electrolysis generating device, set the voltage to 600V - 650V, the duty cycle to 25% - 30%, and the pulse frequency to 220Hz - 250Hz. Conduct the hydrodeoxygenation reaction under plasma electrolysis conditions. After 3min - 4min, the reaction ends, obtaining a reaction product.

[0053] This application uses plasma electrolysis to assist in the hydrodeoxygenation reaction. Plasma is the fourth state of matter different from solids, liquids, and gases. Plasma is also called plasma, which is an ionized gaseous substance composed of positive and negative ions generated after partial electrons are stripped from atoms and atomic groups. Plasma has unique chemical activity and high reaction activity. In this application, plasma electrolysis is introduced into the hydrodeoxygenation reaction. Plasma contains a large number of active particles such as electrons, ions, and free radicals. Driven by a strong electric field, these particles (·CHx, ·OH, ·H, etc.) can not only quickly heat the fuel precursor, but also accelerate the hydrogenation of the fuel precursor. Since the heat comes from the irregular thermal motion of the active particles, the heating process is more uniform and faster, and there is no temperature gradient and lag effect. The reaction time can be shortened to 3min - 4min, and no additional heating is required, avoiding the further polymerization reaction of some organic substances in the fuel precursor under long-term high-temperature heating, thereby obtaining high-stability and high-quality green fuel.

[0054] Specifically, the hydrogen donor is sodium borohydride. Since the hydrogen content in the sodium borohydride molecule is relatively high (about 10.6%), it can provide a large number of hydrogen atoms, enabling it to effectively participate in the hydrodeoxygenation reaction of the oxygen-containing functional groups of the liquefied product, reducing the generation of oxides, and improving the deoxygenation efficiency. Compared with other hydrogen sources, sodium borohydride does not require high-pressure hydrogen equipment, can release hydrogen under relatively mild conditions, and has a relatively low cost.

[0055] The hydrogenation catalyst described in this application includes an active metal component and a zirconium diboride whisker - molecular sieve composite support. Among them, the active metal component includes Mn, Cu, Co, W, and Mo.

[0056] The loading amount of the active metal component in the hydrogenation catalyst is 15% - 25%; among them, the molar ratio of Cu / Co is 1:(0.8 - 1), the molar ratio of Mn / (Cu + Co) is (0.3 - 0.5):1, and the molar ratio of W / Mo is 1:1.

[0057] The hydrogenation catalyst of this application uses Mn, Cu, Co, W, and Mo as the main active components. Mn has strong oxygen reduction activity and can convert between different oxidation states (such as Mn2+ and Mn 3+ ), and this oxygen reduction characteristic enables manganese to catalyze oxidation - reduction reactions, which helps to process oxidizing functional groups during the hydrogenation process and remove oxygen atoms in fuel precursors, such as removing aldehyde groups, carboxyl groups and other oxidizing functional groups, thereby increasing the oil content and energy density of green fuel. Cu has good electronic conductivity, which can enhance the electron transfer performance of the catalyst and improve the reaction efficiency. Co has very high catalytic activity for oxygen atoms on the aromatic ring and can increase the heat resistance of the catalyst. W can provide strong acidity and metal - surface catalytic activity, which helps to improve the reaction selectivity and hydrogenation ability in the hydrodeoxygenation reaction and increase the yield of green fuel. Mo has good activity at high temperatures, which can enhance the stability and activity of the catalyst and promote the hydrodeoxygenation reactions of phenols and aldehydes, and alleviate the problem of catalyst poisoning. By the combined use of Mn, Cu, Co, W, and Mo, the stability and efficiency of the catalyst can be improved, the adsorption and activation of hydrogen can be optimized, the efficiency of the hydrodeoxygenation reaction can be greatly improved, and the oxygen content in green fuel can be reduced.

[0058] Specifically, the preparation steps of the hydrogenation catalyst include:

[0059] Add cellulose ether and starch ether into water at 55°C - 65°C. After keeping warm for 0.8h - 1.2h, add molecular sieve, stir and mix evenly, then add it into a ball - forming machine for rolling treatment. After forming spherical particles, add zirconium diboride whiskers and continue rolling treatment for 3h - 6h to obtain a support precursor;

[0060] Dry the support precursor at 70°C - 80°C for 8h - 12h, and then calcine it at 500°C - 600°C for 2h - 4h to obtain a zirconium diboride whisker - molecular sieve composite support;

[0061] Dissolve the soluble salts of the active metal component in water to obtain an active component solution;

[0062] The zirconium diboride whisker - molecular sieve composite support is impregnated in the active component solution, stirred and mixed evenly, and then left standing for 6 h - 10 h. After drying at 100°C - 120°C for 8 h - 12 h, it is calcined at 400°C - 500°C for 2 h - 4 h to obtain the hydrogenation catalyst.

[0063] Since the molecular sieve has poor adhesiveness, in this application, cellulose ether and starch ether are swollen in water and then mixed with the molecular sieve to improve the adhesiveness of the molecular sieve in the aqueous solution, thereby increasing the binding force between the molecular sieve and the zirconium diboride whiskers. Moreover, in this application, a rolling forming method is adopted. After the molecular sieve forms spherical particles, zirconium diboride whiskers are added, so that the zirconium diboride whiskers are coated on the outer layer of the molecular sieve, forming a core - shell structure with the molecular sieve as the core layer and the zirconium diboride whiskers as the shell layer. The crystal structure of the zirconium diboride whiskers has high mechanical strength and thermal stability. Being on the outer layer of the molecular sieve, it can provide a high - specific - surface - area support structure for the molecular sieve, enabling the metal active components to be more evenly distributed and maintaining good stability. At the same time, the zirconium diboride shell layer can effectively prevent the dissolution and migration of metal components, improving the durability of the catalyst. And because the zirconium diboride whiskers have excellent thermal conductivity, it helps with heat transfer inside the catalyst, avoiding local overheating, thereby maintaining the activity of the catalyst. The porous structure of the molecular sieve core layer provides a reaction space for the oxidation functional groups, promoting their reaction with hydrogen, thus achieving deoxygenation. Through the design of the core - shell structure, the stability of the catalyst is enhanced, and the efficiency of the hydrodeoxygenation reaction is further improved.

[0064] Specifically, the mass ratio of zirconium diboride whiskers to the molecular sieve in the zirconium diboride whisker - molecular sieve composite support is 1:(1 - 1.5).

[0065] The molecular sieve is one or more of ZSM - 5 molecular sieve, ZSM - 35 molecular sieve, and ZSM - 5 / ZSM - 35 eutectic molecular sieve. Preferably, it is the ZSM - 5 / ZSM - 35 eutectic molecular sieve, and its SiO 2 / Al 2 O 3 molar ratio is 25 - 30, the pore diameter is 0.5 nm - 0.6 nm, the specific surface area is 600 m 2 / g - 800 m 2 / g, and the relative crystallinity is 95% - 120%.

[0066] After S40 and centrifugal separation and distillation of the reaction product, green fuel is obtained.

[0067] In the specific implementation process, after centrifugal separation of the reaction product, the filtrate is subjected to vacuum distillation at 60°C to remove organic substances such as methanol, and then green fuel is obtained.

[0068] An embodiment of the present application further provides a highly stable green fuel, which is obtained by using the preparation method of the above-mentioned highly stable green fuel.

[0069] The above technical solutions of the present application will be described in detail below with specific embodiments.

[0070] Example 1

[0071] A preparation method of a highly stable green fuel includes the following steps:

[0072] After crushing 100 g of biomass raw material to a particle size of 90 μm, 500 mL of water, 500 mL of isopropanol, and 40 g of lithium bromide are added to a homogeneous reactor together. After sealing, N 2 is evacuated, and then N at 2 MPa is filled in. 2 As the initial atmosphere, it is heated to 280 °C at a heating rate of 10 °C / min, kept warm for 0.5 h, and stirred at a rotation speed of 170 r / min at the same time. After the reaction ends, it is cooled to room temperature within 10 min to obtain a liquefied product;

[0073] The liquefied product is subjected to vacuum filtration to obtain a filtrate; dichloromethane is used as an extraction solvent to extract the filtrate, and the aqueous phase and the solvent phase are separated; the solvent phase is subjected to vacuum distillation at 37 °C to obtain a fuel precursor;

[0074] 10 g of cellulose ether and 10 g of starch ether are added to 40 mL of water at 60 °C. After keeping warm for 1.0 h, 48 g of molecular sieve is added. After stirring and mixing evenly, it is added to a pelletizer for rolling treatment. After forming spherical particles, 40 g of zirconium diboride whiskers is added, and rolling treatment is continued for 4.5 h to obtain a carrier precursor;

[0075] The carrier precursor is dried at 75 °C for 10 h and then calcined at 550 °C for 3 h to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0076] 1.5 g of Mn(NO 3 ) 2 ·4H 2 O, 2 g of Cu(NO 3 ) 2 2, 1.8 g of Co(NO 3 ) 2 ·6H 2 O, 2.1 g of W(CH 3 COO) 6 2, 2.1 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2Dissolve 0.3 g of O in 100 mL of water to obtain an active component solution;

[0077] Immerse the zirconium diboride whisker - molecular sieve composite support in the active component solution, stir and mix evenly, then let it stand for 8 h, then dry at 110 °C for 10 h, and then calcine at 450 °C for 3 h to obtain a hydrogenation catalyst;

[0078] Mix 10 g of fuel precursor, 3 g of sodium borohydride, 7 g of hydrogenation catalyst and 4.5 g of methanol, and use a plasma electrolysis generator. Set the voltage to 620 V, the duty cycle to 27%, and the pulse frequency to 235 Hz. Carry out the hydrodeoxygenation reaction under plasma electrolysis conditions. After 4 min, the reaction ends to obtain a reaction product;

[0079] After centrifugally separating the reaction product, carry out vacuum distillation at 60 °C to obtain green fuel.

[0080] Example 2

[0081] A preparation method of a highly stable green fuel, comprising the following steps:

[0082] After crushing 100 g of biomass raw material to a particle size of 80 μm, add it together with 500 mL of water, 500 mL of isopropanol and 30 g of lithium bromide into a homogeneous reactor, seal it, and introduce N 2 Carry out evacuation, and then fill in N at 2 MPa 2 As the initial atmosphere, heat it to 260 °C at a heating rate of 8 °C / min, keep it warm for 0.6 h, and at the same time keep stirring at a rotation speed of 160 r / min. After the reaction ends, cool it to room temperature within 10 min to obtain a liquefied product;

[0083] Carry out vacuum filtration on the liquefied product to obtain a filtrate; use dichloromethane as an extraction solvent to extract the filtrate, and separate to obtain an aqueous phase and a solvent phase; carry out vacuum distillation on the solvent phase at 35 °C to obtain a fuel precursor;

[0084] Add 10 g of cellulose ether and 10 g of starch ether to 40 mL of water at 55 °C, keep it warm for 1.2 h, then add 40 g of molecular sieve, stir and mix evenly, then add it to a ball - forming machine for rolling treatment. After forming spherical particles, add 40 g of zirconium diboride whiskers, and continue rolling treatment for 3 h to obtain a support precursor;

[0085] Dry the support precursor at 70 °C for 12 h, and then calcine it at 500 °C for 4 h to obtain a zirconium diboride whisker - molecular sieve composite support;

[0086] Add Mn(NO 3 ) 2 ·4H 2 O 1.8 g, Cu(NO3 ) 2 2 g of Co(NO 3 ) 2 ·6H 2 O, 1.6 g of W(CH 3 COO) 6 2.1 g, (NH 4 ) 6 Mo 7 O 24 ·4H 2 O, 0.3 g are dissolved in 100 mL of water to obtain an active component solution;

[0087] The zirconium diboride whisker - molecular sieve composite support is impregnated in the active component solution. After stirring and mixing evenly, it is left standing for 6 h, then dried at 100 °C for 12 h, and then calcined at 400 °C for 4 h to obtain a hydrogenation catalyst;

[0088] 10 g of a fuel precursor, 2 g of sodium borohydride, 6 g of the hydrogenation catalyst, and 5 g of methanol are mixed, and then, using a plasma electrolysis generating device, the voltage is set to 600 V, the duty cycle is 25%, and the pulse frequency is 220 Hz. A hydrodeoxygenation reaction is carried out under plasma electrolysis conditions. After 4 min, the reaction ends to obtain a reaction product;

[0089] After centrifugally separating the reaction product, vacuum distillation is carried out at 60 °C to obtain green fuel.

[0090] Example 3

[0091] A preparation method of a highly stable green fuel, comprising the following steps:

[0092] After crushing 100 g of biomass raw material to a particle size of 100 μm, it is added together with 500 mL of water, 500 mL of isopropanol, and 50 g of lithium bromide into a homogeneous reactor. After sealing, N 2 is evacuated, and then N 2 at 2 MPa is charged as the initial atmosphere, and then heated to 300 °C at a heating rate of 12 °C / min, kept warm for 0.4 h, and at the same time stirred at a rotation speed of 180 r / min. After the reaction ends, it is cooled to room temperature within 10 min in water to obtain a liquefied product;

[0093] The liquefied product is subjected to vacuum filtration to obtain a filtrate; dichloromethane is used as an extraction solvent to extract the filtrate, and the aqueous phase and the solvent phase are separated; the solvent phase is subjected to vacuum distillation at 40 °C to obtain a fuel precursor;

[0094] Add 10 g of cellulose ether and 10 g of starch ether to 40 mL of water at 65 °C. After heat preservation for 0.8 h, add 60 g of molecular sieve, stir and mix evenly, then add it to a ball-making machine for rolling treatment. After forming spherical particles, add zirconium diboride whiskers and continue rolling treatment for 6 h to obtain a carrier precursor;

[0095] Dry the carrier precursor at 80 °C for 8 h and then calcine it at 600 °C for 2 h to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0096] Dissolve 2 g of Mn(NO 3 ) 2 ·4H 2 O, 2 g of Cu(NO 3 ) 2 2, 2 g of Co(NO 3 ) 2 ·6H 2 O, 2 g of W(CH 3 COO) 6 1.4 g, and 0.2 g of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O in 100 mL of water to obtain an active component solution;

[0097] Immerse the zirconium diboride whisker-molecular sieve composite carrier in the active component solution, stir and mix evenly, then let it stand for 10 h, then dry it at 120 °C for 8 h and then calcine it at 500 °C for 2 h to obtain a hydrogenation catalyst;

[0098] Mix 10 g of fuel precursor, 4 g of sodium borohydride, 6 g of hydrogenation catalyst and 4 g of methanol, and use a plasma electrolysis generator. Set the voltage to 650 V, the duty cycle to 30%, and the pulse frequency to 250 Hz. Carry out hydrogenation deoxygenation reaction under plasma electrolysis conditions. After 3 min, the reaction ends to obtain a reaction product;

[0099] After centrifugal separation of the reaction product, carry out vacuum distillation at 60 °C to obtain green fuel.

[0100] Experimental example

[0101] Test and analyze the contents of C, H, O, and S elements in the green fuel prepared in the examples of this application, and carry out calorific value tests. At the same time, use a common diesel sample as a control group. Among them, the contents of C, H, and O elements are tested according to the GB / T19143-2017 standard, and the content of S element is tested according to the ASTM5453-2016 standard. The test results are shown in Table 1 below; the calorific value test is carried out using a bomb calorimeter and referring to the ASTM D4809 standard, and the test results are shown in Table 2 below.

[0102] Table 1

[0103]

[0104]

[0105] As can be seen from Table 1, the proportion of C element in the green fuel of this application is slightly higher than that of the diesel sample. Its carbon chain length basically meets the requirements for the use of diesel oil products. After hydrodeoxygenation of the green fuel of this application, the proportion of O element drops significantly and is only slightly higher than that of the diesel sample, while the proportion of H element is lower than that of the diesel sample, indicating that this application can effectively reduce the O content in the fuel. At the same time, the S element in the fuel of this application is much lower than that of the diesel sample. Since sulfides in diesel will not only cause corrosion of equipment and aging of the air box, increase the formation of carbon deposits during use, but also generate air pollutants during the combustion process, and the S element content in the green fuel of this application is extremely low, making it more environmentally friendly.

[0106] Table 2

[0107] Group Calorific value (MJ / kg) Example 1 40.15 Example 2 39.62 Example 3 40.35 Diesel sample 43

[0108] As can be seen from Table 2, compared with the calorific value of the ordinary diesel sample, the difference in the calorific value between the green fuel of this application and the ordinary diesel sample is very small. This is mainly because its oxygen content is only slightly higher than that of the ordinary diesel sample and can meet the calorific value requirements for the use of vehicle diesel (the calorific value range of vehicle diesel is generally between 38.7 MJ / kg and 40.5 MJ / kg), indicating that the green fuel of this application has the possibility of replacing diesel.

[0109] The above are only optional embodiments of this application, and do not limit the patent scope of this application accordingly. Any equivalent structural transformation made under the inventive concept of this application by using the content of the specification and drawings of this application, or any direct / indirect application in other related technical fields, is included in the patent protection scope of this application.

Claims

1. A method for preparing a highly stable green fuel, characterized in that: The following steps are involved: After the biomass raw material is crushed, water-isopropanol co-solvent is used as a reaction medium, and a lithium-containing catalyst is added, and heating is performed to carry out a liquefaction reaction to obtain a liquefied product; The liquefied product is filtered, extracted and distilled to obtain a fuel precursor; A hydrogen donor, a hydrogenation catalyst and methanol are added to the fuel precursor, and a plasma electrolysis method is used to assist in a hydrogenation and deoxygenation reaction to obtain a reaction product; The reaction product is centrifuged and distilled to obtain green fuel oil.

2. The method for preparing green fuel with high stability according to claim 1, characterized in that: The step of crushing the biomass raw material, using water-isopropanol co-solvent as a reaction medium, adding a lithium-containing catalyst, heating to carry out a liquefaction reaction, and obtaining a liquefied product comprises: The biomass raw material is crushed to a particle size of 80 μm-100 μm, and water and isopropanol are mixed in a volume ratio of 1:1 as a reaction medium; The crushed biomass raw material, the reaction medium and the lithium-containing catalyst are added together into a homogeneous reactor, which is sealed and evacuated by introducing N2. Then, 2MPa of N2 is introduced as the initial atmosphere, and the reactor is heated to 260-300°C at a heating rate of 8°C / min-12°C / min, and kept warm for 0.4h-0.6h. Meanwhile, the reactor is stirred at a speed of 160r / min-180r / min. After the reaction is completed, the reactor is cooled to room temperature within 10min to obtain a liquefied product.

3. The method for preparing green fuel with high stability according to claim 1, characterized in that: The lithium-containing catalyst is lithium bromide, and the mass ratio of the biomass raw material to the lithium-containing catalyst is 10:(3-5).

4. The method for preparing green fuel with high stability according to claim 1, characterized in that: The step of filtering the liquefied product, extracting and distilling the liquefied product to obtain a fuel precursor comprises: performing vacuum filtration on the liquefied product to obtain a filtrate; Using dichloromethane as an extraction solvent, extracting the filtrate to separate into an aqueous phase and a solvent phase; The solvent phase is subjected to reduced pressure distillation at 35° C.-40° C. to obtain a fuel precursor.

5. The method for preparing green fuel with high stability according to claim 1, characterized in that: In the step of adding a hydrogen donor, a hydrogenation catalyst and methanol to the fuel precursor, the hydrogen donor is sodium borohydride; The hydrogenation catalyst comprises an active metal component and a zirconium diboride whisker-molecular sieve composite carrier, wherein the active metal component comprises Mn, Cu, Co, W and Mo.

6. The method for preparing green fuel with high stability according to claim 5, characterized in that: The loading amount of the active metal component in the hydrogenation catalyst is 15%-25%; wherein the molar ratio of Cu / Co is 1:(0.8-1), the molar ratio of Mn / (Cu+Co) is (0.3-0.5):1, and the molar ratio of W / Mo is 1:1; The mass ratio of the zirconium diboride whisker to the molecular sieve in the zirconium diboride whisker-molecular sieve composite carrier is 1:(1-1.5).

7. The method for preparing green fuel with high stability according to claim 6, characterized in that: The preparation step of the hydrogenation catalyst comprises: Add cellulose ether and starch ether into water at 55° C.-65° C., keep warm for 0.8 h-1.2 h, add the molecular sieve, stir and mix, add into a spheronizer for rolling treatment, after forming spherical particles, add the zirconium diboride whisker, continue rolling treatment for 3 h-6 h, and obtain a carrier precursor; The carrier precursor is dried at 70° C.-80° C. for 8 h-12 h, and then calcined at 500° C.-600° C. for 2 h-4 h to obtain a zirconium diboride whisker-molecular sieve composite carrier; dissolving a soluble salt of the active metal component in water to obtain an active component solution; The zirconium diboride whisker-molecular sieve composite carrier is immersed in the active component solution, stirred and mixed, and then allowed to stand for 6h-10h, and then dried at 100℃-120℃ for 8h-12h, and then calcined at 400℃-500℃ for 2h-4h to obtain the hydrogenation catalyst.

8. The method for preparing high-stability green fuel according to claim 1, characterized in that: In the step of adding a hydrogen donor, a hydrogenation catalyst and methanol to the fuel precursor, the mass ratio of the fuel precursor, the hydrogen donor, the hydrogenation catalyst and the methanol is 1:(0.2-0.4):(0.6-0.8):(4-5).

9. The method for preparing green fuel with high stability according to claim 1, characterized in that: The step of using plasma electrolysis to assist in the hydrodeoxygenation reaction to obtain the reaction product comprises: A plasma electrolysis generating device is used, the voltage is set to 600V-650V, the duty cycle is 25%-30%, the pulse frequency is 220Hz-250Hz, and a hydrogenation deoxygenation reaction is carried out under plasma electrolysis conditions. After 3min-4min, the reaction ends and a reaction product is obtained.

10. A highly stable green fuel, characterized in that: Obtained by the preparation method of the high-stability green fuel as described in any one of claims 1 to 9.

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