Biofuel and preparation method thereof

Abstract

The invention discloses biological fuel oil and a preparation method thereof, and relates to the technical field of biological energy sources. A preparation method of biofuel oil comprises the following steps: drying and crushing a biomass raw material, adopting an acetone system as a reaction medium, adding an ionic liquid catalyst, and heating for liquefaction reaction to obtain a liquefied product; carrying out centrifugal separation on the liquefied product, washing, and carrying out rotary evaporation to obtain a biological fuel oil precursor; adding a hydrogen donor, zero-valent metal, a hydrogenation catalyst and water into the biological fuel oil precursor, heating and stirring in a closed environment, and carrying out hydrodeoxygenation reaction to obtain a reaction product; and carrying out suction filtration and rotary evaporation on the reaction product to obtain the biological fuel oil. The biomass is converted into the biological fuel oil, the oxygen element content of the prepared biological fuel oil is greatly reduced, the heat value is remarkably increased, and the possibility is provided for replacing part of non-renewable energy sources.

Description

Technical Field

[0001] The present application relates to the field of bioenergy technology, and in particular to a biofuel and a preparation method thereof. Background Art

[0002] Biofuel is a renewable, biodegradable, clean energy source. The development and application of biofuel can reduce people's dependence on fossil energy. Biomass resources refer to all organic matter directly or indirectly formed by photosynthesis of green plants, including plants, animals, microorganisms and their excretion and metabolites. It has the advantages of being renewable, low-pollution, widely distributed, carbon neutral, and low in sulfur and nitrogen content. Converting biomass into liquid products by chemical methods to produce biofuel that can be used as a substitute for petroleum diesel is conducive to promoting energy substitution, reducing environmental pressure, and controlling urban air pollution. However, the process of converting biomass into liquid products usually has low reaction efficiency, and the liquid products have a high oxygen content, resulting in a low calorific value, which limits the application of biofuel. Summary of the invention

[0003] The main purpose of this application is to provide a biofuel and a preparation method thereof, aiming to solve the technical problem that the biofuel obtained by biomass conversion has a high oxygen content.

[0004] To achieve the above objectives, the present application proposes a method for preparing biofuel, comprising the following steps:

[0005] After the biomass raw material is dried and crushed, an acetone system is used as a reaction medium, and an ionic liquid catalyst is added, and the liquefaction reaction is carried out by heating to obtain a liquefied product;

[0006] The liquefied product is centrifuged and washed, and then subjected to rotary evaporation to obtain a biofuel precursor;

[0007] Adding a hydrogen donor, a zero-valent metal, a hydrogenation catalyst and water to the biofuel precursor, heating and stirring in a closed environment to perform a hydrogenation and deoxygenation reaction to obtain a reaction product;

[0008] The reaction product is filtered and rotary evaporated to obtain biofuel.

[0009] Optionally, the step of drying and crushing the biomass raw material comprises:

[0010] The biomass raw material is dried at 95°C-110°C for 4h-8h, the moisture content of the dried biomass raw material is controlled between 2wt%-4wt%, and then crushed to a particle size of 80μm-100μm.

[0011] Optionally, in the step of using an acetone system as a reaction medium and adding an ionic liquid catalyst, the acetone system comprises acetone and hydrochloric acid; wherein the mass ratio of acetone to hydrochloric acid is 100:(3-4);

[0012] The ionic liquid catalyst is 1-ethyl-3-methylimidazolium chloride.

[0013] Optionally, the step of heating to carry out liquefaction reaction to obtain a liquefied product comprises:

[0014] A homogeneous reactor was used for the liquefaction reaction. The reaction was heated to 140°C-150°C at a heating rate of 1.2°C / min-1.6°C / min under closed conditions, and then kept warm for 4h-5h. The stirring speed was maintained at 10r / min-15r / min. After the reaction was completed, the reaction was cooled to room temperature to obtain a liquefied product.

[0015] Optionally, the step of centrifugally separating and washing the liquefied product and then performing rotary evaporation to obtain a biofuel precursor comprises:

[0016] The liquefied product is centrifuged several times to obtain a filtrate and a solid residue, and the solid residue is washed several times with acetone, and the washing liquid is collected and rotary evaporated together with the filtrate at 25° C.-32° C. to obtain a biofuel precursor.

[0017] Optionally, in the step of adding a hydrogen donor, a zero-valent metal, a hydrogenation catalyst and water to the biofuel precursor, the hydrogen donor is sodium borohydride;

[0018] The zero-valent metal is at least one of zinc, aluminum, and iron;

[0019] The hydrogenation catalyst comprises an active metal component and a zirconium diboride whisker-molecular sieve composite carrier, wherein the active metal component comprises Ni, 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 Ni / Co is 1:1, the molar ratio of Cu / (Ni+Co) is (0.4-0.8):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 molecular sieve and the zirconium diboride whisker are ball-milled for 10 h to 15 h, dried at 70° C. to 80° C. for 8 h to 12 h, and then calcined at 500° C. to 600° C. for 2 h to 4 h to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0024] dissolving a soluble salt of the active metal component in water to obtain an active component solution;

[0025] 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.

[0026] Optionally, the step of heating and stirring in a closed environment to perform a hydrodeoxygenation reaction to obtain a reaction product comprises:

[0027] After hydrogen is introduced for purging, the mixture is heated to 240°C-400°C in a closed reactor at a heating rate of 3°C / min-4°C / min, and kept warm for 0.5h-1h. Meanwhile, the mixture is stirred at a speed of 160r / min-200r / min to carry out a hydrodeoxygenation reaction. After the reaction is completed, the mixture is water-cooled to room temperature within 8min-12min to obtain a reaction product.

[0028] The present application also proposes a biofuel obtained by the above-mentioned biofuel preparation method.

[0029] This application includes at least the following beneficial effects:

[0030] The present application first liquefies the biomass raw material, and uses an acetone-ionic liquid catalyst as a liquefaction system. The ionic liquid catalyst can convert cellulose, hemicellulose and lignin in the biomass into low molecular weight intermediates. These intermediates can be further reacted and converted in an acetone solvent to form a furan-based biofuel precursor. At the same time, acetone itself also undergoes a condensation reaction, so that the liquefied products mainly include furfural-acetone, 5-hydroxymethylfurfural-acetone, acetone-acetone, etc., which together constitute the effective components of the biofuel precursor, reduce the generation and treatment steps of by-products, and improve the reaction efficiency and the yield of the liquefied product.

[0031] The present application further performs a hydrogenation and deoxygenation treatment on the biofuel precursor to reduce the oxygen content and increase the calorific value. A stable, efficient and environmentally friendly hydrogen supply system is provided by a hydrogen supply agent, a zero-valent metal and a hydrogenation catalyst. The zero-valent metal can react with the water phase to produce in-situ hydrogen to avoid the problem of insufficient hydrogen supply that may occur in the hydrogen supply agent and ensure the supply of hydrogen. At the same time, the metal oxide generated by the zero-valent metal also has a catalytic effect, thereby producing a synergistic acceleration effect with the hydrogenation catalyst, further promoting the deoxygenation reaction of the biofuel precursor and increasing the yield of the biofuel. The hydrogenation and deoxygenation efficiency is significantly higher than that of the commonly used external gaseous hydrogen, and the reaction conditions are also milder. The hydrocarbon compound content in the biofuel is significantly increased, the oxygen-containing compound content is greatly reduced, and the calorific value is significantly increased.

[0032] The carbon chain length distribution of the biofuel in the present application is mainly C5-C18, while diesel is a mixture of various hydrocarbons. The liquefied product of the present application meets the carbon chain length requirements of diesel oil products, and after hydrodeoxygenation treatment, the oxygen content is greatly reduced, and the calorific value is significantly improved, which has the potential to replace some non-renewable energy (such as diesel). BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. It is obvious that 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.

[0034] Figure 1 This is a flow chart of the method for preparing biofuel described in an embodiment of the present application.

[0035] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] In view of the technical problems existing in the prior art, the embodiments of the present application provide a method for preparing biofuel, such as Figure 1 As shown, the following steps are included:

[0038] S10, drying and crushing the biomass raw material, using an acetone system as a reaction medium, adding an ionic liquid catalyst, heating to perform a liquefaction reaction, and obtaining a liquefied product.

[0039] In the specific implementation process, the step of drying and crushing the biomass raw material includes:

[0040] The biomass raw material is dried at 95°C-110°C for 4h-8h, the moisture content of the dried biomass raw material is controlled between 2wt%-4wt%, and then crushed to a particle size of 80μm-100μm.

[0041] 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. After catalytic degradation, cellulose, hemicellulose and lignin can be degraded into liquid intermediates with high or low molecular mass and reactive activity (i.e., biofuel precursors), which are then used to prepare biofuel.

[0042] Specifically, the acetone system includes acetone and hydrochloric acid; wherein the mass ratio of acetone to hydrochloric acid is 100:(3-4).

[0043] The present application adopts acetone as the liquefaction solvent, and adds an appropriate amount of hydrochloric acid to provide protons for the reaction. During the catalytic liquefaction process, the glycosidic bonds of cellulose and hemicellulose in the biomass raw materials are first broken to generate monosaccharide structures such as glucose and xylose. The monosaccharide structures are unstable and continue to be hydrolyzed to generate furfural and 5-hydroxymethylfurfural and their derivatives with furan rings, and then undergo aldol condensation reaction with acetone to generate furan-based biofuel precursors. At the same time, the reaction solvent acetone itself also undergoes condensation reaction to jointly constitute the biofuel precursor components, thereby improving the yield of the liquefied product and reducing the generation of by-products.

[0044] The ionic liquid catalyst used in this application is 1-ethyl-3-methylimidazolium chloride, and the mass ratio of biomass raw material to 1-ethyl-3-methylimidazolium chloride is 5:(1-3). 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 ionic liquid catalysis, providing a better reaction matrix for the liquefaction reaction. 1-ethyl-3-methylimidazolium chloride can effectively promote the pyrolysis and cracking of biomass in the catalytic liquefaction reaction. During the high-temperature liquefaction process, biomass may experience some undesirable side reactions (such as excessive cracking, coke formation, etc.). 1-ethyl-3-methylimidazolium chloride as a catalyst can adjust the reaction environment and reduce the incidence of these side reactions.

[0045] In a specific implementation process, the step of heating to carry out liquefaction reaction to obtain a liquefied product includes:

[0046] A homogeneous reactor was used for the liquefaction reaction. The reaction was heated to 140°C-150°C at a heating rate of 1.2°C / min-1.6°C / min under closed conditions, and then kept warm for 4h-5h. The stirring speed was maintained at 10r / min-15r / min. After the reaction was completed, the reaction was cooled to room temperature to obtain a liquefied product.

[0047] The present application adopts acetone-ionic liquid catalyst as the liquefaction system. The polarity and solubility characteristics of acetone can help improve the interaction between biomass and 1-ethyl-3-methylimidazolium chloride catalyst, and provide a good solvent environment for 1-ethyl-3-methylimidazolium chloride. 1-ethyl-3-methylimidazolium chloride can convert cellulose, hemicellulose and lignin in biomass into low molecular weight intermediates. These intermediates can further react and transform in acetone solvent to form different liquid products. The combination of acetone and 1-ethyl-3-methylimidazolium chloride catalyst helps to reduce the reaction Temperature, and improve the thermal stability of the reaction, so that the reaction can be carried out under relatively mild conditions, the reaction efficiency is improved, and the formation of certain by-products is inhibited, and the yield and quality of the liquefied product are improved. The liquefied product obtained after catalytic liquefaction mainly includes furfural-acetone, 5-hydroxymethylfurfural-acetone, acetone-acetone, etc. The carbon chain length distribution is mainly C5-C18, and the relative molecular weight is mostly less than 300. Diesel is a mixture of various hydrocarbons. The liquefied product of the present application meets the carbon chain length of diesel oil products, and at the same time reduces the generation and treatment steps of by-products, thereby improving the reaction efficiency and the yield of the liquefied product.

[0048] S20, centrifugally separating and washing the liquefied product, and then performing rotary evaporation to obtain a biofuel precursor.

[0049] In the specific implementation process, the liquefied product is centrifuged multiple times to obtain a filtrate and a solid residue, and the solid residue is washed multiple times with acetone, and the washing liquid is collected and rotary evaporated together with the filtrate at 25° C.-32° C. to obtain a biofuel precursor.

[0050] S30, adding a hydrogen donor, a zero-valent metal, a hydrogenation catalyst and water to the biofuel precursor, heating and stirring in a closed environment to perform a hydrogenation and deoxygenation reaction to obtain a reaction product.

[0051] In the specific implementation process, hydrogen is first introduced to purge the reactor, and then the reactor is sealed and heated to 240°C-400°C at a heating rate of 3°C / min-4°C / min, and kept warm for 0.5h-1h. At the same time, the rotation speed is maintained at 160r / min-200r / min for stirring to carry out hydrodeoxygenation reaction. After the reaction is completed, it is water-cooled to room temperature within 8min-12min to obtain a reaction product.

[0052] Specifically, the hydrogen supply agent is sodium borohydride. Since the hydrogen content in sodium borohydride molecules is relatively high (about 10.6%), it can provide a large number of hydrogen atoms, so that it can effectively participate in the hydrogenation and deoxygenation reaction of the oxygen-containing functional groups of the liquefied product, reduce the generation of oxides, and improve the deoxygenation efficiency. Compared with other hydrogen sources, sodium borohydride does not require high-pressure hydrogen equipment, can release hydrogen under milder conditions, and has a relatively low cost.

[0053] The zero-valent metal in the present application is at least one of zinc, aluminum, and iron. The zero-valent metal can react with the water phase to produce in-situ hydrogen to avoid the problem of insufficient hydrogen supply that may occur in sodium borohydride. At the same time, the generated metal oxide can also serve as a catalyst, and has a synergistic acceleration effect with the hydrogenation catalyst, further promoting the deoxygenation reaction of the biofuel precursor, significantly increasing the content of hydrocarbon compounds in the biofuel, greatly reducing the content of oxygen-containing compounds, and significantly improving the calorific value.

[0054] The hydrogenation catalyst described in the present application comprises an active metal component and a zirconium diboride whisker-molecular sieve composite carrier, wherein the active metal component comprises Ni, Cu, Co, W and Mo.

[0055] The loading amount of the active metal component in the hydrogenation catalyst is 15%-25%; wherein the molar ratio of Ni / Co is 1:1, the molar ratio of Cu / (Ni+Co) is (0.4-0.8):1, and the molar ratio of W / Mo is 1:1.

[0056] Specifically, the preparation steps of the hydrogenation catalyst include:

[0057] The molecular sieve and zirconium diboride whisker are ball-milled for 10h-15h, dried at 70°C-80°C for 8h-12h, and calcined at 500°C-600°C for 2h-4h to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0058] dissolving a soluble salt of the active metal component in water to obtain an active component solution;

[0059] 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.

[0060] The hydrogenation catalyst of the present application uses Ni, Cu, Co, W and Mo as main active ingredients. Ni can effectively promote the reaction of oxides (such as phenols, aldehydes, acids) with hydrogen, thereby reducing the oxygen content in the biofuel precursor. 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 aromatic rings and can increase the heat resistance of the catalyst. W can provide strong acidity and metal surface catalytic activity, which helps to improve the selectivity and hydrogenation ability of the reaction in the hydrodeoxygenation reaction and increase the yield of biofuel. Mo has good activity at high temperature, which can enhance the stability and activity of the catalyst, and promote the hydrodeoxygenation reaction of phenols and aldehydes, and reduce the problem of catalyst poisoning. Through the combined use of Ni, Cu, Co, W and Mo, the efficiency of the hydrodeoxygenation reaction is greatly improved, and the oxygen content of biofuel is reduced.

[0061] Specifically, the mass ratio of zirconium diboride whiskers to molecular sieves in the zirconium diboride whisker-molecular sieve composite carrier is 1:(1-1.5).

[0062] The molecular sieve is one of Y-type molecular sieve, β-molecular sieve, ZSM-5 molecular sieve, SAPO molecular sieve, and MCM-41 molecular sieve, preferably Y-type molecular sieve, wherein SiO 2 / Al 2 O 3 The molar ratio is 18-30 and the pore volume is 0.25cm 3 / g-0.40cm 3 / g, specific surface area is 800m 2 / g-1000m 2 / g, and the relative crystallinity is 90%-120%.

[0063] The present application uses zirconium diboride whisker composite molecular sieve as a hydrogenation catalyst carrier. The crystal structure of zirconium diboride whiskers has high mechanical strength and thermal stability. After being composited with molecular sieves, it can provide a support structure with a high specific surface area, so that the metal active components can be evenly distributed and maintain good stability. In addition, due to the special structure of zirconium diboride whiskers, it can help regulate the size and distribution of the molecular sieve pores and effectively limit the penetration of large molecular reactants. In the hydrogenation and deoxygenation reaction, this pore structure helps to selectively remove oxygen elements and avoid unnecessary side reactions. Since by-products may poison the catalyst surface and reduce the catalytic activity, the zirconium diboride whisker-molecular sieve composite carrier helps to reduce the deactivation of the catalyst and extend the service life of the catalyst through its excellent stability and anti-poisoning ability. At the same time, zirconium diboride also has a strong hydrogen adsorption capacity, so that the composite carrier can effectively adsorb hydrogen, improve the utilization efficiency of hydrogen in the reaction, further improve the efficiency of the reaction, and thus increase the yield of biofuel.

[0064] S40, filtering and rotary distilling the reaction product to obtain biofuel.

[0065] In the specific implementation process, the reaction product is vacuum filtered through a solvent filter to separate the solid and liquid, and then the filtrate is rotary evaporated at 34° C. to remove volatile organic substances such as acetone.

[0066] The embodiments of the present application also provide a biofuel obtained by the above-mentioned biofuel preparation method.

[0067] The above technical solution of the present application is described in detail below in conjunction with specific embodiments.

[0068] Example 1

[0069] A method for preparing biofuel comprises the following steps:

[0070] 100 g of biomass raw material was dried at 100° C. for 6 h, the moisture content was controlled to be 3 wt %, and then crushed to a particle size of 90 μm. 1000 g of acetone and 35 g of hydrochloric acid were mixed, and 30 g of 1-ethyl-3-methylimidazolium chloride was added, and added together with the crushed biomass raw material into a homogeneous reactor for liquefaction reaction. After heating to 145° C. at a heating rate of 1.4° C. / min under closed conditions, the mixture was kept warm for 4.5 h, and stirred at a speed of 12 r / min. After the reaction was completed, the mixture was cooled to room temperature to obtain a liquefied product.

[0071] The liquefied product is centrifuged multiple times to obtain a filtrate and a solid residue, and the solid residue is washed multiple times with acetone, and the washing liquid is collected and rotary evaporated together with the filtrate at 29° C. to obtain a biofuel precursor;

[0072] By mechanical ball milling, 10 g of zirconium diboride whisker and 12 g of molecular sieve were ball milled for 12 h, dried at 75° C. for 10 h, and calcined at 550° C. for 3 h to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0073] Will Ni(NO 3 ) 2 6H 2 O 2g, Cu(NO 3 ) 2 2.4g, Co(NO 3 ) 2 6H 2 O 2g、W(CH 3 COO 6 1.4 g, (NH 4 ) 6 Mo 7 O 24 ·4H2 O 0.2 g was dissolved in 100 mL of water to obtain an active ingredient solution;

[0074] The zirconium diboride whisker-molecular sieve composite carrier was immersed in the active component solution, stirred and mixed, and then allowed to stand for 8 hours, and then dried at 110°C for 10 hours, and then calcined at 450°C for 3 hours to obtain a hydrogenation catalyst;

[0075] After hydrogen was introduced into the reactor for purging, 10 g of biofuel precursor, 4 g of sodium borohydride, 2 g of iron, 10 g of hydrogenation catalyst and 150 mL of water were added into the reactor and sealed, and heated to 300° C. at a heating rate of 3.5° C. / min, and kept warm for 0.7 h, while stirring at a speed of 180 r / min to carry out a hydrodeoxygenation reaction. After the reaction was completed, the reaction was cooled to room temperature within 10 min to obtain a reaction product;

[0076] The reaction product is vacuum filtered and then rotary evaporated at 34° C. to obtain biofuel.

[0077] Example 2

[0078] A method for preparing biofuel comprises the following steps:

[0079] 100 g of biomass raw material was dried at 95° C. for 8 h, the moisture content of the dried biomass raw material was controlled to be 2 wt %, and then crushed to a particle size of 80 μm. 1000 g of acetone and 30 g of hydrochloric acid were mixed, and 30 g of 1-ethyl-3-methylimidazolium chloride was added, and added together with the crushed biomass raw material into a homogeneous reactor for liquefaction reaction. After heating to 140° C. at a heating rate of 1.2° C. / min under closed conditions, the mixture was kept warm for 5 h, and stirred at a speed of 10 r / min. After the reaction was completed, the mixture was cooled to room temperature to obtain a liquefied product.

[0080] The liquefied product is centrifuged multiple times to obtain a filtrate and a solid residue, and the solid residue is washed multiple times with acetone, and the washing liquid is collected and rotary evaporated together with the filtrate at 25° C. to obtain a biofuel precursor;

[0081] By mechanical ball milling, 10 g of zirconium diboride whisker and 10 g of molecular sieve were ball milled and mixed for 10 h, dried at 70° C. for 12 h, and calcined at 500° C. for 4 h to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0082] Will Ni(NO 3 ) 2 6H 2 O 2g, Cu(NO 3 ) 2 1.6g, Co(NO 3 )2 6H 2 O 2g、W(CH 3 COO 6 1.4 g, (NH 4 ) 6 Mo 7 O 24 ·4H 2 O 0.2 g was dissolved in 100 mL of water to obtain an active ingredient solution;

[0083] The zirconium diboride whisker-molecular sieve composite carrier was impregnated 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 then calcined at 400°C for 4 hours to obtain a hydrogenation catalyst;

[0084] After hydrogen was introduced into the reactor for purging, 10 g of biofuel precursor, 4 g of sodium borohydride, 2 g of zinc, 8 g of hydrogenation catalyst and 150 mL of water were added into the reactor and sealed, and then heated to 250° C. at a heating rate of 3° C. / min, and kept warm for 1 h, while stirring at a speed of 160 r / min to carry out a hydrodeoxygenation reaction. After the reaction was completed, the reaction was cooled to room temperature within 8 min to obtain a reaction product;

[0085] The reaction product is vacuum filtered and then rotary evaporated at 34° C. to obtain biofuel.

[0086] Example 3

[0087] A method for preparing biofuel comprises the following steps:

[0088] 100 g of biomass raw material was dried at 110° C. for 4 h, the moisture content of the dried biomass raw material was controlled to be 4 wt %, and then crushed to a particle size of 100 μm. 1000 g of acetone and 40 g of hydrochloric acid were mixed, and 30 g of 1-ethyl-3-methylimidazolium chloride was added, and added together with the crushed biomass raw material into a homogeneous reactor for liquefaction reaction. After heating to 150° C. at a heating rate of 1.6° C. / min under closed conditions, the mixture was kept warm for 4 h, and stirred at a speed of 15 r / min. After the reaction was completed, the mixture was cooled to room temperature to obtain a liquefied product.

[0089] The liquefied product is centrifuged multiple times to obtain a filtrate and a solid residue, and the solid residue is washed multiple times with acetone, and the washing liquid is collected and rotary evaporated together with the filtrate at 32° C. to obtain a biofuel precursor;

[0090] By mechanical ball milling, 10 g of zirconium diboride whisker and 15 g of molecular sieve were ball milled for 15 h, dried at 80° C. for 8 h, and calcined at 600° C. for 2 h to obtain a zirconium diboride whisker-molecular sieve composite carrier;

[0091] Will Ni(NO 3 ) 2 6H 2 O 3g, Cu(NO 3 ) 2 3.6g, Co(NO 3 ) 2 6H 2 O 3g、W(CH 3 COO 6 2.1 g, (NH 4 ) 6 Mo 7 O 24 ·4H 2 O 0.3 g was dissolved in 100 mL of water to obtain an active ingredient solution;

[0092] The zirconium diboride whisker-molecular sieve composite carrier is impregnated in the active component solution, stirred and mixed, and then allowed to stand for 10 hours, and then dried at 120°C for 8 hours, and then calcined at 500°C for 2 hours to obtain a hydrogenation catalyst;

[0093] After hydrogen was introduced into the reactor for purging, 12 g of biofuel precursor, 4 g of sodium borohydride, 1 g of aluminum, 1 g of iron, 10 g of hydrogenation catalyst and 150 mL of water were added into the reactor and sealed, the reactor was sealed and heated to 350° C. at a heating rate of 4° C. / min, kept warm for 0.5 h, and stirred at a speed of 200 r / min to carry out a hydrodeoxygenation reaction. After the reaction was completed, the reaction was cooled to room temperature within 12 min to obtain a reaction product, and a reaction product was obtained;

[0094] The reaction product is vacuum filtered and then rotary evaporated at 34° C. to obtain biofuel.

[0095] Experimental example

[0096] The C, H, O, and S element contents in the biofuel prepared in the examples of the present application were tested and analyzed, and the calorific value test was performed, and the ordinary diesel sample was used as the control group. The C, H, and O element contents were tested in accordance with the GB / T19143-2017 standard, and the S element content was tested in accordance with the ASTM5453-2016 standard, and the test results are shown in Table 1 below; the calorific value test was performed using a bomb calorimeter and in accordance with the ASTM D4809 standard, and the test results are shown in Table 2 below.

[0097] Table 1

[0098] Group C (m%) H(m%) O(m%) S(mg / L) Example 1 82.1 16.9 1.7 2.2 Example 2 81.8 16.4 1.8 2.9 Example 3 81.6 16.7 1.7 2.0 Diesel samples 85.1 14.1 0.9 14.6

[0099] As can be seen from Table 1, since the carbon chain length distribution of the biofuel of the present application is mainly C5-C18, which basically meets the carbon chain length used by diesel oil products, the proportion of C element is only slightly lower than that of the diesel sample, and after hydrogenation and deoxygenation, the proportion of H element of the biofuel of the present application is very close to that of the diesel sample, and the proportion of O element is only slightly higher than that of the diesel sample. However, the S element of the biofuel 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, but also increase the formation of carbon deposits during use, and will also generate atmospheric pollutants during combustion. The S element content in the biofuel of the present application is extremely low, indicating that it is more environmentally friendly.

[0100] Table 2

[0101] Group Calorific value (MJ / kg) Example 1 39.37 Example 2 38.70 Example 3 38.88 Diesel samples 43

[0102] As can be seen from Table 2, compared with the calorific value of the diesel sample, the calorific value of the biofuel of the present application is slightly lower, mainly because its oxygen content is higher, and the calorific value is affected to a certain extent by the oxygen content, but it can basically meet the calorific value requirements for automotive diesel (the calorific value range of automotive diesel is roughly between 38.7MJ / kg-40.5MJ / kg), indicating that the biofuel of the present application has the possibility of being used as diesel.

[0103] The above are only optional embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes 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 biofuel, characterized in that: The following steps are involved: After the biomass raw material is dried and crushed, an acetone system is used as a reaction medium, and an ionic liquid catalyst is added, and the liquefaction reaction is carried out by heating to obtain a liquefied product; The liquefied product is centrifuged and washed, and then subjected to rotary evaporation to obtain a biofuel precursor; Adding a hydrogen donor, a zero-valent metal, a hydrogenation catalyst and water to the biofuel precursor, heating and stirring in a closed environment to perform a hydrogenation and deoxygenation reaction to obtain a reaction product; The reaction product is filtered and rotary evaporated to obtain biofuel.

2. The method for preparing biofuel according to claim 1, characterized in that: The step of drying and crushing the biomass raw material comprises: The biomass raw material is dried at 95°C-110°C for 4h-8h, the moisture content of the dried biomass raw material is controlled between 2wt%-4wt%, and then crushed to a particle size of 80μm-100μm.

3. The method for preparing biofuel according to claim 1, characterized in that: In the step of using an acetone system as a reaction medium and adding an ionic liquid catalyst, the acetone system comprises acetone and hydrochloric acid; wherein the mass ratio of acetone to hydrochloric acid is 100:(3-4); The ionic liquid catalyst is 1-ethyl-3-methylimidazolium chloride.

4. The method for preparing biofuel according to claim 1, characterized in that: The step of heating to carry out liquefaction reaction to obtain a liquefied product comprises: A homogeneous reactor was used for the liquefaction reaction. The reaction was heated to 140°C-150°C at a heating rate of 1.2°C / min-1.6°C / min under closed conditions, and then kept warm for 4h-5h. The stirring speed was maintained at 10r / min-15r / min. After the reaction was completed, the reaction was cooled to room temperature to obtain a liquefied product.

5. The method for preparing biofuel according to claim 1, characterized in that: The step of centrifugally separating and washing the liquefied product and then performing rotary evaporation to obtain a biofuel precursor comprises: The liquefied product is centrifuged several times to obtain a filtrate and a solid residue, and the solid residue is washed several times with acetone, and the washing liquid is collected and rotary evaporated together with the filtrate at 25° C.-32° C. to obtain a biofuel precursor.

6. The method for preparing biofuel according to claim 1, characterized in that: In the step of adding a hydrogen donor, a zero-valent metal, a hydrogenation catalyst and water to the biofuel precursor, the hydrogen donor is sodium borohydride; The zero-valent metal is at least one of zinc, aluminum, and iron; The hydrogenation catalyst comprises an active metal component and a zirconium diboride whisker-molecular sieve composite carrier, wherein the active metal component comprises Ni, Cu, Co, W and Mo.

7. The method for preparing biofuel according to claim 6, characterized in that: The loading amount of the active metal component in the hydrogenation catalyst is 15%-25%; wherein the molar ratio of Ni / Co is 1:1, the molar ratio of Cu / (Ni+Co) is (0.4-0.8):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).

8. The method for preparing biofuel according to claim 7, characterized in that: The preparation step of the hydrogenation catalyst comprises: The molecular sieve and the zirconium diboride whisker are ball-milled for 10 h to 15 h, dried at 70° C. to 80° C. for 8 h to 12 h, and then calcined at 500° C. to 600° C. for 2 h to 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.

9. The method for preparing biofuel according to claim 1, characterized in that: The step of heating and stirring in a closed environment to perform a hydrodeoxygenation reaction to obtain a reaction product comprises: After hydrogen is introduced for purging, the mixture is heated to 240°C-400°C in a closed reactor at a heating rate of 3°C / min-4°C / min, and kept warm for 0.5h-1h. Meanwhile, the mixture is stirred at a speed of 160r / min-200r / min to carry out a hydrodeoxygenation reaction. After the reaction is completed, the mixture is water-cooled to room temperature within 8min-12min to obtain a reaction product.

10. A biofuel, characterized in that: Obtained by the biofuel preparation method according to any one of claims 1 to 9.

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