A high-stability green fuel and its preparation method

Abstract

The present application discloses a highly stable green fuel and a preparation method thereof, relating to the field of green energy preparation technology. A method for preparing a highly stable green fuel comprises the following steps: crushing a biomass raw material, using a 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; filtering the liquefied product, extracting and distilling it to obtain a fuel precursor; adding a hydrogen donor, a hydrogenation catalyst, and methanol to the fuel precursor, and using plasma electrolysis to assist in a hydrodeoxygenation reaction to obtain a reaction product; centrifuging and distilling the reaction product to obtain a green fuel. The present application significantly improves the reaction efficiency, avoids excessive condensation of the reaction product, reduces the content of oxygenated compounds, and significantly increases the calorific value, thereby obtaining a highly stable, high-quality green fuel.

Description

Technical Field

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

[0002] With the development of society, humanity's demand for liquid energy is increasing. Currently, fossil fuels such as coal, oil, and natural gas remain the primary energy sources for the normal operation and development of human society. However, existing fossil energy reserves are limited, and their use also generates significant amounts of carbon dioxide and other toxic gases. Green fuels, on the other hand, refer to fuels produced from renewable resources or through environmentally friendly processes. They are low-carbon, renewable, and environmentally friendly, offering a complementary energy source to fossil fuels and optimizing the energy mix. Biomass, a diverse and abundant source of biomass energy, is the fourth largest energy source after coal, oil, and natural gas, making it a crucial component of the energy mix. Biomass refers to various organic materials formed through photosynthesis, including plants, microorganisms, and animal waste. It boasts advantages such as renewability, low pollution, widespread distribution, carbon neutrality, and low sulfur and nitrogen content. Chemically converting biomass into liquid energy to produce green fuels, which can be used as a diesel alternative, will promote energy substitution, alleviate environmental pressures, and control urban air pollution.

[0003] However, in the biomass conversion process, the reaction time is usually long and the reaction efficiency is low. The liquid product further undergoes polymerization reaction at high temperature, resulting in the obtained liquid product being unstable and the oxygen content is usually high, resulting in its low calorific value. The high calorific value is usually less than 20MJ / 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 fuel.

[0005] To achieve the above objectives, the present application proposes a method for preparing a highly stable green fuel, comprising the following steps:

[0006] After the biomass raw material is crushed, water-isopropanol co-solvent is used as the reaction medium, and a lithium-containing catalyst is added, and the mixture is heated to carry out a liquefaction reaction to obtain a liquefied product;

[0007] The liquefied product is filtered, extracted, and distilled to obtain a fuel precursor;

[0008] Adding a hydrogen donor, a hydrogenation catalyst and methanol to the fuel precursor, and using plasma electrolysis to assist in a hydrogenation and deoxygenation reaction to obtain a reaction product;

[0009] The reaction product is centrifuged and distilled to obtain green fuel oil.

[0010] Optionally, the step of crushing the biomass raw material, using 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 in a volume ratio of 1:1 as a reaction medium;

[0012] The crushed biomass raw material, the reaction medium and the lithium-containing catalyst are added together into a homogeneous reactor. After sealing, N2 is introduced for evacuation, and then 2MPa of N2 is filled as the initial atmosphere. The reactor is heated to 260°C-300°C at a heating rate of 8°C / min-12°C / min, kept warm for 0.4h-0.6h, and stirred at a speed of 160r / min-180r / min. After the reaction is completed, the reactor is water-cooled to room temperature within 10 minutes 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, extracting, and distilling the liquefied product to obtain a fuel precursor includes:

[0015] performing vacuum filtration on the liquefied product to obtain a filtrate;

[0016] The filtrate is extracted using dichloromethane as an extraction solvent to separate into an aqueous phase and a solvent phase;

[0017] The solvent phase is subjected to reduced pressure 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 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.

[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 the zirconium diboride whisker to the molecular sieve in the zirconium diboride whisker-molecular sieve composite carrier is 1:(1-1.5).

[0022] Optionally, the step of preparing the hydrogenation catalyst comprises:

[0023] The cellulose ether and starch ether are added to water at 55° C. to 65° C., kept warm for 0.8 h to 1.2 h, and then the molecular sieve is added. After stirring and mixing, the mixture is added to a pelletizer for rolling. After spherical particles are formed, the zirconium diboride whiskers are added and the rolling process is continued for 3 h to 6 h to obtain a carrier precursor.

[0024] The carrier precursor is dried at 70-80° C. for 8-12 hours, and then calcined at 500-600° C. for 2-4 hours to obtain a zirconium diboride whisker-molecular sieve composite carrier;

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

[0026] The zirconium diboride whisker-molecular sieve composite carrier is immersed in the active component solution, stirred and mixed, and then allowed to stand for 6 hours to 10 hours. Then, it is dried at 100° C. to 120° C. for 8 hours to 12 hours, and then calcined at 400° C. to 500° C. for 2 hours to 4 hours 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 the reaction product comprises:

[0029] A plasma electrolysis generating device is used, the voltage is set to 600V-650V, the duty cycle is 25%-30%, and the pulse frequency is 220Hz-250Hz. A hydrogenation and deoxygenation reaction is carried out under plasma electrolysis conditions. After 3min-4min, the reaction is completed to obtain a reaction product.

[0030] The present application also proposes a high-stability green fuel obtained by the above-mentioned preparation method of the high-stability green fuel.

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

[0032] The present invention first liquefies the biomass raw material, uses water-isopropanol co-solvent as the reaction medium, and adds a lithium-containing catalyst to assist in catalysis, thereby releasing a large amount of H + and OH - , causing the dielectric constant to drop sharply, thereby significantly increasing the solubility of lipophilic hydrophobic organic matter such as lignin in water, and isopropyl alcohol can be decomposed into acetone and active hydrogen. Active hydrogen can promote the depolymerization and hydrogenation of biomass to reduce the oxygen content of the liquefied product, which is beneficial to the subsequent preparation of green fuel with lower oxygen content. The acetone decomposed by isopropyl alcohol can react with the aldehyde compounds generated by the hydrolysis of cellulose and hemicellulose to undergo aldol condensation reaction to generate furan compounds, thereby improving the energy density of the liquefied product. Under the liquefaction system of the present application, the cellulose and hemicellulose in the biomass raw materials are mainly hydrolyzed to generate furfural, 2-furancarboxaldehyde, 5-methyl-2-furancarboxaldehyde and 2-hydroxy-2-cyclopentanone, and further condensed with acetone to generate furan compounds. The lignin is mainly hydrolyzed to generate 2-methoxyphenol and 2,6-dimethoxyphenol, which together constitute the effective components of the fuel precursor;

[0033] The present application further performs a hydrodeoxygenation treatment on the fuel precursor to reduce the oxygen content and increase the calorific value. Plasma electrolysis is also introduced 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. Because the heat comes from the irregular thermal motion of the active particles, the heating process is more uniform and faster, without temperature gradients and hysteresis effects. The reaction time can be significantly shortened, and no additional heating is required. The reaction conditions are milder, and further polymerization of some organic matter in the fuel precursor under long-term high-temperature heating is avoided. The hydrocarbon compound content in the green fuel is significantly increased, the oxygen-containing compound content is greatly reduced, and the calorific value is significantly improved, thereby obtaining a highly stable, high-quality green fuel with a carbon chain length distribution mainly between C5 and C18, which is consistent with the carbon chain length used in diesel oil and has the potential to replace the use of some non-renewable energy sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0035] Figure 1 This is a flow chart of the method for preparing the highly stable green fuel described in the embodiments of this application.

[0036] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0038] In view of the technical problems existing in the prior art, the embodiments of the present application provide a method for preparing a highly stable green fuel, such as Figure 1 As shown, the following steps are included:

[0039] S10, after the biomass raw material is crushed, a water-isopropanol co-solvent is used as a reaction medium, and a lithium-containing catalyst is added, and heating is performed to perform a liquefaction reaction to obtain a liquefied product.

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

[0041] In a specific implementation process, 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;

[0042] The crushed biomass raw material, the reaction medium and the lithium-containing catalyst are added together into a homogeneous reactor. After sealing, N2 is introduced for evacuation, and then 2MPa of N2 is filled as the initial atmosphere. The reactor is heated to 260°C-300°C at a heating rate of 8°C / min-12°C / min, kept warm for 0.4h-0.6h, and stirred at a speed of 160r / min-180r / min. After the reaction is completed, the reactor is water-cooled to room temperature within 10 minutes to obtain a liquefied product.

[0043] This application uses water-isopropanol co-solvent as the reaction medium. Water can act as a non-polar solvent, making it a reaction medium for organic compounds. At the same time, when the water temperature rises to a certain level, the ionization degree of water increases significantly, releasing more H + and OH - , which causes the dielectric constant to drop sharply, thereby greatly increasing the solubility of lipophilic hydrophobic organic substances such as lignin in water, and even achieving miscibility with oil. Due to the low viscosity and high solubility of hydrophobic organic substances, water can be used as a reaction medium and has a catalytic effect. However, the efficiency of relying solely on water after qualitative change to liquefy and degrade biomass is very limited. Therefore, this application adds isopropyl alcohol as a reaction medium. Isopropyl alcohol itself is a good medium for organic reactions. Under the reaction conditions and with the assistance of a lithium-containing catalyst, isopropyl alcohol can be decomposed into acetone and active hydrogen, and active hydrogen can promote the depolymerization and hydrogenation of biomass to reduce the oxygen content of the liquefied product. , which is conducive to the subsequent preparation of green fuel with lower oxygen content, and the acetone decomposed by isopropyl alcohol can react with the aldehyde compounds generated by the hydrolysis of cellulose and hemicellulose to undergo aldol condensation reaction to generate furan compounds, which have the advantages of high energy density and high octane number, and are an organic matter that meets the requirements of gasoline, diesel and aviation kerosene. At the same time, isopropyl alcohol can also serve as a collector for reaction intermediates, such as phenols and aldehyde compounds, to inhibit their repolymerization through reactions such as hydrogenation, alkylation or esterification, thereby reducing the formation of coke by-products, so that the present application obtains a liquefied product with higher stability and quality under the reaction medium of water-isopropyl alcohol 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, the solubility of these components can be improved by using lithium bromide for catalysis, 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 biomass by the reaction medium, and thus accelerate the reaction process. At the same time, lithium bromide, as a strong polar catalyst, can promote charge transfer between molecules, change the polarity of the reaction medium, and promote the degradation of cellulose, hemicellulose and lignin, causing them to break down and generate monosaccharide structures such as glucose and xylose. However, the monosaccharide structure is unstable and continues to hydrolyze to generate important furan compounds such as furfural with a furan ring.

[0046] S20, filtering the liquefied product, and then extracting and distilling it to obtain a fuel precursor.

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

[0048] The filtrate is extracted using dichloromethane as an extraction solvent to separate into an aqueous phase and a solvent phase;

[0049] The solvent phase is subjected to reduced pressure distillation at 35° C.-40° C. to remove dichloromethane, thereby obtaining a fuel precursor.

[0050] S30, adding a hydrogen donor, a hydrogenation catalyst and methanol to the fuel precursor, and performing a hydrogenation and deoxygenation reaction assisted by plasma electrolysis to obtain a reaction product.

[0051] 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).

[0052] In the specific implementation process, a plasma electrolysis generator is used, the voltage is set to 600V-650V, the duty cycle is 25%-30%, and the pulse frequency is 220Hz-250Hz. The hydrodeoxygenation reaction is carried out under plasma electrolysis conditions. After 3min-4min, the reaction is completed to obtain the reaction product.

[0053] This application uses plasma electrolysis to assist in the hydrodeoxygenation reaction. Plasma is the fourth state of matter, distinct from solids, liquids, and gases. Plasma, also known as plasma, is an ionized gaseous substance composed of positive and negative ions produced by the ionization of atoms and atomic groups stripped of some electrons. Plasma has unique chemical activity and high reactivity. This application introduces plasma electrolysis 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. Because the heat comes from the irregular thermal motion of the active particles, the heating process is more uniform and faster, without temperature gradients or hysteresis effects. The reaction time can be shortened to 3-4 minutes without the need for additional heating, avoiding further polymerization of some organic matter in the fuel precursor under long-term high-temperature heating, thereby obtaining a highly stable, high-quality green fuel.

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

[0055] The hydrogenation catalyst described in the present application includes an active metal component and a zirconium diboride whisker-molecular sieve composite carrier, wherein 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%; 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.

[0057] The hydrogenation catalyst of the present 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+ ), this oxygen-reducing property enables manganese to catalyze redox reactions, helping to treat oxidizing functional groups during the hydrogenation process and remove oxygen atoms from fuel precursors, such as oxidized functional groups such as aldehydes and carboxyl 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 reaction efficiency. Co has very high catalytic activity for oxygen atoms on aromatic rings and can increase the heat resistance of the catalyst. W can provide strong acidity and metal surface catalytic activity, helping to improve the selectivity and hydrogenation capacity of the reaction 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, promote the hydrodeoxygenation reaction of phenols and aldehydes, and alleviate the problem of catalyst poisoning. The combined use of Mn, Cu, Co, W, and Mo can improve the stability and efficiency of the catalyst, optimize the adsorption and activation of hydrogen, greatly improve the efficiency of the hydrodeoxygenation reaction, and reduce the oxygen content in green fuel.

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

[0059] Add cellulose ether and starch ether to water at 55-65°C, keep warm for 0.8-1.2 hours, add molecular sieves, stir and mix, then add to a pelletizer for rolling treatment to form spherical particles, then add zirconium diboride whiskers, and continue rolling treatment for 3-6 hours to obtain a carrier precursor;

[0060] The carrier precursor is dried at 70-80° C. for 8-12 hours, and then calcined at 500-600° C. for 2-4 hours to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0061] dissolving a soluble salt of the active metal component in water to obtain an active component solution;

[0062] The zirconium diboride whisker-molecular sieve composite carrier is immersed in the active component solution, stirred and mixed, and then allowed to stand for 6 hours to 10 hours. Then, it is dried at 100° C. to 120° C. for 8 hours to 12 hours, and then calcined at 400° C. to 500° C. for 2 hours to 4 hours to obtain the hydrogenation catalyst.

[0063] Since the molecular sieve has weak adhesion, the present application adopts cellulose ether and starch ether to swell in water and then mix with the molecular sieve to improve the adhesion of the molecular sieve in the aqueous solution, thereby increasing the binding force between the molecular sieve and the zirconium diboride whiskers. In addition, the present application adopts a rolling molding method. After the molecular sieve forms spherical particles, zirconium diboride whiskers are added to coat 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, and it can provide a molecular sieve with a strong adhesion to the outer layer of the molecular sieve. The support structure with a high specific surface area enables the metal active components to be more evenly distributed and maintain good stability. At the same time, the zirconium diboride shell can effectively prevent the dissolution and migration of metal components, thereby improving the durability of the catalyst. In addition, since the zirconium diboride whiskers have excellent thermal conductivity, they help heat transfer inside the catalyst and avoid local overheating, thereby maintaining the activity of the catalyst. The porous structure of the molecular sieve core layer provides reaction space for the oxidizing functional groups, promoting their reaction with hydrogen, thereby achieving deoxygenation. The core-shell structure design enhances the stability of the catalyst and further improves the efficiency of the hydrodeoxygenation reaction.

[0064] Specifically, the mass ratio of the zirconium diboride whiskers to the molecular sieve in the zirconium diboride whisker-molecular sieve composite carrier 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 ZSM-5 / ZSM-35 eutectic molecular sieve, which has a SiO2 / Al2O3 molar ratio of 25-30, a pore size of 0.5nm-0.6nm, and a specific surface area of ​​600m 2 / g-800m 2 / g, and the relative crystallinity is 95%-120%.

[0066] S40, centrifugally separating and distilling the reaction product to obtain green fuel.

[0067] In the specific implementation process, after the reaction product is centrifuged, the filtrate is subjected to reduced pressure distillation at 60°C to remove organic matter such as methanol, thereby obtaining green fuel.

[0068] The embodiments of the present application also provide a high-stability green fuel obtained by the above-mentioned method for preparing the high-stability green fuel.

[0069] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0070] Example 1

[0071] A method for preparing a highly stable green fuel comprises the following steps:

[0072] 100 g of biomass raw material was crushed to a particle size of 90 μm, and then added to a homogeneous reactor together with 500 mL of water, 500 mL of isopropanol, and 40 g of lithium bromide. After sealing, N2 was introduced to evacuate the reactor, and then 2 MPa of N2 was filled as the initial atmosphere. The reactor was heated to 280°C at a heating rate of 10°C / min and kept warm for 0.5 h while stirring at a speed of 170 r / min. After the reaction was completed, the reactor was cooled to room temperature within 10 min to obtain a liquefied product.

[0073] The liquefied product is vacuum filtered to obtain a filtrate; the filtrate is extracted with dichloromethane as an extraction solvent to separate an aqueous phase and a solvent phase; the solvent phase is subjected to reduced pressure distillation at 37° C. to obtain a fuel precursor;

[0074] 10 g of cellulose ether and 10 g of starch ether were added to 40 mL of water at 60°C, kept warm for 1.0 h, and then 48 g of molecular sieves were added. After stirring and mixing, the mixture was added to a spheroidizer and rolled to form spherical particles. 40 g of zirconium diboride whiskers were then added and the rolling process was continued for 4.5 h to obtain a carrier precursor.

[0075] The carrier precursor was 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] Combine Mn(NO3)2·4H2O 1.5g, Cu(NO3)2 2g, Co(NO3)2·6H2O 1.8g, W(CH3COO) 62.1g, (NH4)6Mo7O 24 Dissolve 0.3 g of 4H2O in 100 mL of water to obtain an active ingredient solution;

[0077] The zirconium diboride whisker-molecular sieve composite support was impregnated in the active component solution, stirred and mixed, and then allowed to stand for 8 hours, then dried at 110°C for 10 hours, and calcined at 450°C for 3 hours to obtain a hydrogenation catalyst;

[0078] After mixing 10g of fuel precursor, 3g of sodium borohydride, 7g of hydrogenation catalyst and 4.5g of methanol, a plasma electrolysis generator was used to perform a hydrodeoxygenation reaction under plasma electrolysis conditions with a set voltage of 620V, a duty cycle of 27%, and a pulse frequency of 235Hz. After 4 minutes, the reaction was completed to obtain a reaction product.

[0079] The reaction product is centrifuged and then distilled under reduced pressure at 60° C. to obtain green fuel oil.

[0080] Example 2

[0081] A method for preparing a highly stable green fuel comprises the following steps:

[0082] 100 g of biomass raw material was crushed to a particle size of 80 μm, and then added to a homogeneous reactor together with 500 mL of water, 500 mL of isopropanol, and 30 g of lithium bromide. After sealing, N2 was introduced to evacuate the reactor, and then 2 MPa of N2 was filled as the initial atmosphere. The reactor was heated to 260°C at a heating rate of 8°C / min and kept warm for 0.6 h while stirring at a speed of 160 r / min. After the reaction was completed, the reactor was cooled to room temperature within 10 min to obtain a liquefied product.

[0083] The liquefied product is vacuum filtered to obtain a filtrate; the filtrate is extracted with dichloromethane as an extraction solvent to separate an aqueous phase and a solvent phase; the solvent phase is subjected to reduced pressure distillation at 35° C. to obtain a fuel precursor;

[0084] 10 g of cellulose ether and 10 g of starch ether were added to 40 mL of water at 55°C, kept warm for 1.2 h, and then 40 g of molecular sieves were added. After stirring and mixing, the mixture was added to a spheroidizer and rolled to form spherical particles. 40 g of zirconium diboride whiskers were then added and the rolling process was continued for 3 h to obtain a carrier precursor.

[0085] The carrier precursor was dried at 70°C for 12 hours and then calcined at 500°C for 4 hours to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0086] Combine Mn(NO3)2·4H2O 1.8g, Cu(NO3)2 2g, Co(NO3)2·6H2O 1.6g, W(CH3COO) 62.1g, (NH4)6Mo7O 24 Dissolve 0.3 g of 4H2O in 100 mL of water to obtain an active ingredient solution;

[0087] The zirconium diboride whisker-molecular sieve composite support was immersed in the active component solution, stirred and mixed, and then allowed to stand for 6 hours, and then dried at 100°C for 12 hours, and calcined at 400°C for 4 hours to obtain a hydrogenation catalyst;

[0088] After mixing 10g of fuel precursor, 2g of sodium borohydride, 6g of hydrogenation catalyst and 5g of methanol, a plasma electrolysis generator was used to perform a hydrodeoxygenation reaction under plasma electrolysis conditions with a set voltage of 600V, a duty cycle of 25%, and a pulse frequency of 220Hz. After 4 minutes, the reaction was completed to obtain a reaction product.

[0089] The reaction product is centrifuged and then distilled under reduced pressure at 60° C. to obtain green fuel oil.

[0090] Example 3

[0091] A method for preparing a highly stable green fuel comprises the following steps:

[0092] 100 g of biomass raw material was crushed to a particle size of 100 μm, and then added into a homogeneous reactor together with 500 mL of water, 500 mL of isopropanol, and 50 g of lithium bromide. After sealing, N2 was introduced to evacuate the reactor, and then 2 MPa of N2 was filled as the initial atmosphere. The reactor was heated to 300°C at a heating rate of 12°C / min and kept warm for 0.4 h while stirring at a speed of 180 r / min. After the reaction was completed, the reactor was cooled to room temperature within 10 min to obtain a liquefied product.

[0093] The liquefied product is vacuum filtered to obtain a filtrate; the filtrate is extracted with dichloromethane as an extraction solvent to separate an aqueous phase and a solvent phase; the solvent phase is subjected to reduced pressure distillation at 40° C. to obtain a fuel precursor;

[0094] 10 g of cellulose ether and 10 g of starch ether were added to 40 mL of water at 65°C, kept warm for 0.8 h, and then 60 g of molecular sieves were added. After stirring and mixing, the mixture was added to a spheroidizer and rolled to form spherical particles. Then, zirconium diboride whiskers were added and the rolling process was continued for 6 h to obtain a carrier precursor.

[0095] The carrier precursor was dried at 80°C for 8 h and then calcined at 600°C for 2 h to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0096] Combine Mn(NO3)2·4H2O 2g, Cu(NO3)2 2g, Co(NO3)2·6H2O 2g, W(CH3COO) 61.4g, (NH4)6Mo7O 24 Dissolve 0.2 g of 4H2O in 100 mL of water to obtain an active ingredient solution;

[0097] The zirconium diboride whisker-molecular sieve composite support was impregnated in the active component solution, stirred and mixed, and then allowed to stand for 10 hours, then dried at 120°C for 8 hours, and calcined at 500°C for 2 hours to obtain a hydrogenation catalyst;

[0098] After mixing 10g of fuel precursor, 4g of sodium borohydride, 6g of hydrogenation catalyst and 4g of methanol, a plasma electrolysis generator was used to perform a hydrodeoxygenation reaction under plasma electrolysis conditions with a set voltage of 650V, a duty cycle of 30%, and a pulse frequency of 250Hz. After 3 minutes, the reaction was completed to obtain a reaction product.

[0099] The reaction product is centrifuged and then distilled under reduced pressure at 60° C. to obtain green fuel oil.

[0100] Experimental example

[0101] The green fuel prepared in the examples of this application was tested for its C, H, O, and S content, and its calorific value was also tested. A conventional diesel sample served as a control. The C, H, and O content was tested according to the GB / T19143-2017 standard, while the S content was tested according to the ASTM5453-2016 standard. The test results are shown in Table 1 below. The calorific value was tested using a bomb calorimeter according to the ASTM D4809 standard. 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 the present application is slightly higher than that of the diesel sample, which basically meets the carbon chain length of diesel oil products. After hydrogenation and deoxygenation, the proportion of O element in the green fuel of the present application drops significantly, only slightly higher than that of the diesel sample, and the proportion of H element is lower than that of the diesel sample, indicating that the present application can effectively reduce the O content in the fuel. At the same time, the S element in the fuel of the present application is much lower than that of the diesel sample. The presence of sulfides in diesel will not only cause corrosion of equipment and aging of the bellows, and increase the formation of carbon deposits during use, but also generate atmospheric pollutants during combustion. The S element content in the green fuel of the present application is extremely low, which is 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 samples 43

[0108] As can be seen from Table 2, compared with the calorific value of ordinary diesel samples, the calorific value of the green fuel of the present application is very close to that of ordinary diesel samples, mainly because its oxygen content is only slightly higher than that of ordinary diesel samples, and it can meet the calorific value requirements for automotive diesel use (the calorific value range of automotive diesel is roughly between 38.7MJ / kg and 40.5MJ / kg), indicating that the green fuel of the present application has the potential to replace diesel.

[0109] The above are merely optional embodiments of the present application and do not limit the patent scope of the present application. All equivalent structural transformations made using the contents of the present application specification and drawings under the inventive concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A method for preparing a highly stable green fuel, characterized in that: The following steps are involved: 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 to serve 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, and then filled with 2 MPa of N2 as an initial atmosphere, and heated to 260°C-300°C at a heating rate of 8°C / min-12°C / min, and kept warm for 0.4h-0.6h while stirring at a speed of 160r / min-180r / min. After the reaction is completed, the reaction is cooled to room temperature within 10 minutes to obtain a liquefied product; 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); 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 generator is used. The voltage is set to 600V-650V, the duty cycle is set to 25%-30%, and the pulse frequency is set to 220Hz-250Hz. A hydrodeoxygenation reaction is carried out under plasma electrolysis conditions. After 3min-4min, the reaction is completed to obtain a reaction product. The hydrogen donor is sodium borohydride; the hydrogenation catalyst includes an active metal component and a zirconium diboride whisker-molecular sieve composite carrier, wherein the active metal component includes Mn, Cu, Co, W, and Mo. The reaction product is centrifuged and distilled to obtain green fuel oil.

2. The method for preparing a highly stable green fuel 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; The filtrate is extracted using dichloromethane as an extraction solvent 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.

3. The method for preparing high-stability green fuel according to claim 1, 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).

4. The method for preparing a highly stable green fuel according to claim 3, characterized in that: The preparation step of the hydrogenation catalyst comprises: The cellulose ether and starch ether are added to water at 55° C. to 65° C., kept warm for 0.8 h to 1.2 h, and then the molecular sieve is added. After stirring and mixing, the mixture is added to a pelletizer for rolling. After spherical particles are formed, the zirconium diboride whiskers are added and the rolling process is continued for 3 h to 6 h to obtain a carrier precursor. The carrier precursor is dried at 70-80° C. for 8-12 hours, and then calcined at 500-600° C. for 2-4 hours 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 6 hours to 10 hours. Then, it is dried at 100° C. to 120° C. for 8 hours to 12 hours, and then calcined at 400° C. to 500° C. for 2 hours to 4 hours to obtain the hydrogenation catalyst.

5. 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).

6. A highly stable green fuel, characterized by: The green fuel is obtained by the preparation method of the high-stability green fuel according to any one of claims 1 to 5.

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