CN105132003B - Preparation method for biological aircraft fuel - Google Patents

Abstract

The invention relates to a method for preparing aircraft fuel from a biomass resource through hydrogenolysis, condensation and deoxygenation. The method comprises: carrying out hydrogenation and hydrogenolysis on the biomass resource rich in hydroxyl and derivatives thereof to obtain a dihydric alcohol product and a mono-alcohol product; then condensing the mono-alcohol product under an efficient condensation catalyst to obtain high carbon chain branch chain alcohol; and then carrying out hydrogenation and deoxidization to obtain a hydrocarbon mixture rich in branched hydrocarbon, and obtaining a highly-branched product with the boiling range in an aircraft fuel range by reasonably regulating the condensation process.

Description

A kind of preparation method of bio-based aviation fuel

technical field

The invention relates to a method for preparing aviation fuel, which belongs to the fields of green chemical technology and bioenergy technology, in particular to a method for preparing aviation fuel from biomass resources through hydrogenolysis, condensation and deoxygenation reactions.

Background technique

Generally, aviation fuel is a product that is separated from mineral oil by distillation and has a boiling point in the range of aviation fuel. With the continuous depletion of petrochemical resources and the increasing demand for fuels, the shortage of liquid fuels will be a prominent problem that plagues the sustainable development of mankind. Actively looking for alternatives to fossil fuels has become the focus of attention of countries all over the world. Biomass resources are the only renewable resources on earth that can be converted into liquid fuels. As a resource that has been used by humans for thousands of years, it has attracted widespread attention in recent years. The production of bioethanol from corn and agricultural and forestry wastes, and biodiesel and bio-aviation kerosene produced from jatropha oil and palm oil in recent years have begun to be used on different means of transportation. Biofuels have become the world's fuel market An important part of the industry, with broad prospects for development.

At present, there are two main routes to prepare fuels from biomass. One is to use oil resources to obtain alkanes that meet fuel standards through hydrodeoxygenation and isomerization processes; the other is to use synthesis gas route through Fischer-Tropsch Synthetic preparation of specific ranges of alkanes.

Grease is very rich in resources and has a carbon skeleton of a composite liquid fuel. Vegetable oils such as corn, rapeseed, rapeseed, soybean, algal oil; animal fats such as tallow, fish oil and gutter oil. These glyceride and fatty acid sources form a broad category for the production of renewable fuels. In CN 101952392A, Global Oil Company discloses that a fatty acid and fatty acid ester undergoes hydrogenation, decarboxylation, decarbonylation, hydroisomerization and selective cracking to prepare aviation fuel. In US 4300009, Mobil Oil Company discloses the use of a crystalline aluminosilicate zeolite in converting vegetable oil and algae oil into hydrocarbons such as gasoline. In CN102027097A, Global Oil Company discloses a method for producing a hydrocarbon product stream with a boiling point in the aviation fuel range from vegetable and animal oils. The method includes hydrogenation, deoxygenation, isomerization and selective addition Hydrogenation, deoxygenation, isomerization and selective hydrocracking of raw materials in a multifunctional catalyst with hydrocracking function or a single reactor of a group of catalysts to produce renewable raw materials with 9-16 carbon atoms and high iso/normal Ratio of paraffins.

In US 4992605 is disclosed a process for the preparation of hydrocarbon products in the diesel boiling range by hydrotreating vegetable oils. In CN 103320153 A, Tianjin Nankai University Castor Engineering Technology Co., Ltd. discloses a preparation method of castor-based bio-aviation fuel. The method uses castor oil as raw material, obtains normal alkanes through hydrodeoxygenation reaction, and then hydrogenates The isomerization reaction produces isoparaffins, and the fractions are fractionated to obtain the final products.

Fischer-Tropsch synthesis is a process of synthesizing liquid hydrocarbons or hydrocarbons with synthesis gas (mixed gas of carbon monoxide and hydrogen) as raw material under appropriate conditions and catalysts. Syngas can be produced from biomass or fossil resources through cracking, pyrolysis, reforming and other processes. In CN102124085A, Sasol Technology Co., Ltd. discloses a method for preparing aviation fuel by Fischer-Tropsch method. The fuel is used as fuel itself or as a component of aviation fuel mixture. The isoparaffin and normal paraffin of the fuel are The mass ratio is 3 or more.

However, no matter starting from oil resources or through Fischer-Tropsch synthesis, the raw materials for their synthesis are straight-chain alkanes, which need to be further isomerized or blended to meet the needs of aviation fuels.

Contents of the invention

Aiming at the problems existing in the above-mentioned prior art, the present invention provides a method for preparing bio-based aviation fuel. In this method, hydrogenation and hydrogenolysis of hydroxyl-rich biomass resources and their derivatives can obtain di Alcohol products and monoalcohol products, and then the monoalcohol products can be condensed under the high-efficiency condensation catalyst to obtain high-carbon chain branched alcohols, and then further hydrodeoxygenation can obtain hydrocarbon mixtures rich in branched alkanes, through reasonable regulation of the condensation process , products with highly branched boiling ranges within the range of aviation fuels can be obtained.

Specifically, the preparation method of the present invention is a method for preparing alkanes that can be used as aviation fuel from renewable raw materials, comprising the following steps:

1) Under a hydrogen atmosphere of 0.5-12MPa, preferably 4-6MPa, add biomass raw materials or biomass-derived raw materials, multifunctional catalyst a and reaction solvent into the hydrogenolysis reactor to hydrocrack the raw materials to generate monoalcohols and carbon branches Diols with chains of 2 to 6 and other polyol product mixtures, the reaction temperature is 160-260°C, preferably 180-220°C, the reaction time is 1-5 hours, preferably 2-3 hours, and refined by vacuum distillation The reactor separates monoalcohol and diol products from the product mixture, and other polyol products are returned to the hydrogenolysis reactor of this step for further hydrogenolysis reaction;

2) Add the dibasic alcohol product, multifunctional catalyst b and reaction solvent separated in step 1) into another hydrogenolysis reactor for further hydrogenolysis, so that the dibasic alcohol product reacts to become a monoalcohol, wherein the other hydrogen The hydrogen pressure in the decomposition reactor is 0.5-12MPa, preferably 4-8MPa, the reaction temperature is 80-215°C, preferably 120-180°C, and the reaction time is 1-5 hours, preferably 2-3 hours;

3) The monoalcohol obtained in step 1) and 2) is combined, and together with the multifunctional catalyst c, cocatalyst and reaction solvent, add in the condensation reaction kettle to carry out condensation preparation carbon number is 9 to 20 carbon atoms, and branched chain number is 2 to 6 branched chain higher monoalcohol products, wherein the reaction temperature is 80-220°C, preferably 160-200°C, and the reaction time is 2-48 hours, preferably 10-30 hours; and

4) Under a hydrogen atmosphere of 0.5-12MPa, preferably 5-8MPa, in a hydrodeoxygenation reactor, the high alcohol obtained in step 3) is contacted with a multifunctional hydrogenation catalyst d in a reaction solvent for hydrodeoxygenation, and the reaction Temperature 150-350 ℃, preferably 200-300 ℃, reaction contact time 1-20 hours, preferably 2-8 hours, the carbon branching of 9 to 20 carbon atoms is prepared as the branched alkanes of 2 to 6, and the material stream obtained The alkane product with a boiling range within the range of aviation fuel is obtained by separation in a rectification tower.

Preferably, the preparation method according to the present invention further comprises the following steps:

1a) A step of pre-treating the biomass raw material or biomass-derived raw material before performing step 1), in which the biomass raw material or biomass-derived raw material is subjected to e.g. washing, decolorization, ion exchange Processes such as removal of toxic and harmful substances to catalysts used in subsequent steps.

Preferably, the reaction solvent used in step 1) can be one or more selected from water, methanol, ethanol, propanol, butanol, acetaldehyde, propionaldehyde and acetone, preferably a mixture of water, methanol and ethanol As the reaction solvent, the weight ratio of water, methanol and ethanol is 1:0.5-0.8:0.2-0.5, preferably 1:0.5:0.5.

In the preparation method according to the present invention, the biomass raw material or biomass-derived raw material in step 1) includes straw, sawdust, syrup, pulp, cellulose, hemicellulose, glucose, fructose, xylose, arabic One or more of sugar, sorbitol, mannitol, xylitol, arabitol, and glycerin.

In step 1), the multifunctional catalyst a comprises a sulfide selected from elemental metals of group VIII, elemental metals of group _IB , elemental metals of group _{VIB, elemental metals of group VII B and} the metals of the above-mentioned groups loaded on zeolite, Silica, alumina, silica-alumina, activated carbon and components selected from oxides of metals of group VIII, oxides of metals of group I _B , oxides of metals of group VI _B , oxides of metals of group VII _B composed of catalysts.

Preferably, the multifunctional catalyst a in step 1) is one or two of Ru, Ni, Cu, Co, Mo, Re, W supported on ZnO, ZrO ₂ , alumina, zeolite and/or Or catalysts prepared on activated carbon, preferably Ni-ZnO supported catalysts, Ni-Cu/ZrO ₂ supported catalysts, Ni-Cu/ZnO supported catalysts or Ni-W/Al ₂ O ₃ supported catalysts.

Preferably, the multifunctional catalyst b in step 2) is a catalyst selected from the group consisting of Pt, Rh, Ru, Ir, W, Re, and Mo supported on ZrO ₂ , alumina, zeolite, alumina, and activated carbon, preferably It is Rh-Mo/ZrO ₂ supported catalyst, Rh-Re/Al ₂ O ₃ supported catalyst or Ru-W/Al ₂ O ₃ supported catalyst.

Preferably, the reaction solvent used in step 2) can be selected from water, dioxane, methanol, ethanol, propanol solvent, preferably one or more of water, methanol and ethanol.

Preferably, the multifunctional catalyst c in step 3) is a catalyst prepared by loading one or two of Pd, Pt, Rh, Ru, and Ir on activated carbon, preferably a catalyst prepared by loading Pd and Ir on activated carbon.

Preferably, the reaction solvent used in step 3) can be one or more selected from methanol, ethanol, cyclohexane, and n-hexane.

Preferably, the cocatalyst described in step 3) is one or two selected from o-phenanthroline, sodium hydroxide, potassium hydroxide potassium phosphate, tetraethylamine hydroxide, preferably o-phenanthroline and hydrogen sodium oxide.

Preferably, the multifunctional catalyst d in step 4) is prepared by loading one or two of Pt, Ru, Ni, Mo, Re, W on alumina, silica-alumina, zeolite The catalyst is preferably Pt-Mo supported on silica-alumina.

Preferably, for the alkanes with less than 9 carbon atoms or less than 2 carbon branch chains in the branched alkane products obtained through condensation in step 4), they are separated and reenter the condensation reactor of step 4) for reaction.

Preferably, the reaction solvent used in step 4) can be one or more selected from methanol, cyclohexane, and n-hexane.

Preferably, the branched alkanes in step 4) preferably include branched alkanes with 9 to 15 carbon atoms and 2 to 3 carbon chains.

Further preferably, the branched alkane described in step 4) is preferably a branched alkane selected from the following compounds:

Beneficial effect

1) In the present invention, the condensation method is adopted to realize the formation of the branched carbon skeleton, and the process is easy to control, which has obvious advantages over the traditional hydroisomerization method.

2) The branched alkanes obtained according to the preparation method of the present invention are similar in molecular structure to petroleum-based jet fuel, low in sulfur content, high in flash point, and low in emissions after combustion, and do not need to replace the engine and fuel system, It is an important way for the aviation industry to reduce carbon emissions and achieve the goal of green and sustainable development.

3) Compared with other technologies, the technology for preparing aviation fuels of the present invention does not rely on petrochemicals as raw materials, and is inexhaustible; only a few series of catalytic reactions can be used to obtain the product. Compared with other technologies, the process has mild and green reaction conditions.

4) The preparation method of the present invention has broad application prospects, the used process flow is simple, less investment, low energy consumption, high yield, less pollution, and easy process control, suitable for industrial production.

detailed description

In the hydrogenolysis reactor in step 1) of the preparation method according to the present invention, the hydrogen pressure is in the range of 0.5-12MPa, preferably 4-6MPa. If it is less than 0.5MPa, the reaction is difficult to carry out; if it is greater than 12MPa, the reaction rate is too fast, and the reactants are excessively cracked, resulting in the presence of too many by-products of lower alkanes in the product.

In the hydrogenolysis reactor according to step 1) of the preparation method of the present invention, the reaction temperature should be controlled at 160-260°C, preferably 180-220°C, and the reaction time is 1-5 hours, preferably 2-3 hours, If the reaction temperature is too low or too high, or the reaction time is too long or too short, it is not conducive to the selection of alcohol reaction products, especially for monoalcohols and diols.

In addition, the reaction solvent used in step 1) of the preparation method according to the present invention can be one or more selected from water, methanol, ethanol, propanol, butanol, acetaldehyde, propionaldehyde and acetone, A mixture of water, methanol and ethanol is preferred as the reaction solvent, and the weight ratio of water, methanol and ethanol is 1:0.5-0.8:0.2-0.5, preferably 1:0.5:0.5. When the mixture of water, methanol and ethanol is used as the reaction solvent, it can effectively inhibit the excessive cracking of the C-C bond in the reactant, thereby preventing the formation of undesired lower alkanes (such as methane, ethane, etc.) or gaseous products such as carbon dioxide. When the ratio of the three solvents in the mixed solvent of water, methanol and ethanol is within the above range, it can ensure that the hydrogenolysis reaction is milder, and plays a certain "buffer" effect on the hydrogenolysis reaction, so that the monoalcohol and diol in the product Maximize selectivity.

Similarly, in the hydrogenolysis reactor in step 2) of the preparation method according to the present invention, it is necessary to properly control the hydrogen pressure to be 0.5-12MPa, preferably 4-8MPa, and the reaction temperature to be 80-215°C, preferably 120-180°C, The reaction time is 1-5 hours, preferably 2-3 hours. When the reaction conditions are within this range, the highest selectivity of monoalcohol in the product can be ensured, the reaction by-products are the least, and the optimization of reaction efficiency can be realized.

In step 3) of the preparation method according to the present invention, in addition to the selection of the multifunctional catalyst c and the reaction solvent, the use of a cocatalyst is very important, and the cocatalyst is selected from o-phenanthroline, sodium hydroxide, hydrogen Potassium oxide potassium phosphate, one or both of tetraethylamine hydroxide, preferably o-phenanthroline and sodium hydroxide. In the case of only adopting the multifunctional catalyst c without using a cocatalyst, the reaction yield of this step 3) is very low, and the number of branches of the branched high-valent monoalcohol as the product is difficult to control in addition, and it is easy to generate a large amount of straight chain monoalcohols, which cannot be used in aviation fuel.

The composition and preparation method of the catalyst a, b, c, d used in the step 1) to 4) of the preparation method according to the present invention can refer to existing known techniques in the prior art, such as impregnation method, Preparation by co-precipitation and deposition-precipitation methods, and then reduction activation in hydrogen atmosphere or in liquid media with reducing properties such as formaldehyde, formic acid, sodium formate, methanol, ethanol, propanol, butanol, hydrazine hydrate, sodium borohydride, vitamin C, etc. Reductive activation in, for example, can follow "catalyst preparation process technology", Zhang Jiguang, China Petrochemical Press, 2004 and Ertl, G.; H.; Weitkamp, J., Handbook of heterogeneous catalysis.1997 published in the general method. The selection and content of catalyst active components can be selected according to the desired product.

The present invention will be further described below in conjunction with specific embodiments. Embodiment is only enumerated as the example of the embodiment of the present invention, does not constitute any limitation to the present invention, and those skilled in the art can understand that the modification in the scope of not departing from the essence and the design of the present invention all falls into the protection domain of the present invention .

Example 1

Step 1a): breaking the straw, washing the pretreated straw with water, and enzymatically hydrolyzing it to obtain a rough sugar liquid, the main ingredients of the rough sugar liquid include glucose, xylose, arabinose, xylan, cellobiose, trisaccharide and other soluble Oligosaccharides and sugar degradation products, such as furfural, 5-hydroxymethylfurfural, etc., make the sugar concentration in the solution reach 10-50wt%, all soluble sugars are decolorized by activated carbon, and the ion exchange method is used to remove Catalyst Poisonous and harmful substances.

Step 1): pump 500 ml of the saccharification solution obtained in step 1a) into the hydrogenolysis reactor at a concentration of 20 wt% of the saccharified biomass raw material, and simultaneously add methanol and ethanol to prevent the excessive cracking of the sugar liquid raw material in the hydrogenolysis reactor as Solvent, solvent methanol, ethanol add-on is 0.5 times of the water consumption in the sugar solution, then add the Ni-Cu-ZnO catalyst 5g that prepares with co-precipitation-gel method and reductive activation in 500 ℃ of hydrogen (for example can disclose according to CN102286548 prepared by the method), and reacted for 2 hours under the reaction conditions of 180°C and 6MPa hydrogen atmosphere to obtain the hydrogenolysis liquid. Alcohols such as erythritol, glycerin, mannitol, sorbitol, etc. are returned to the hydrogenolysis reactor.

Step 2): adjust the dibasic alcohol obtained in step 1) to be 50% aqueous solution and pump it into another _{hydrogenolysis} reactor, and add Rh/SiO prepared by impregnation Catalyst 10g (for example, according to Wang, XC; Wu, F.; Yao, SX; Jiang, YJ; Guan, J.; Mui, XD, Ni-Cu/ZnO-catalyzed Hydrogenolysis of Cellulose for the Production of 1,2-Alkanediols in Hot Compressed Water. Chemistry Letters 2012,41, (5), prepared by the method disclosed in 476-478), reacted for 12h under the reaction conditions of 120°C and 8MPa hydrogen atmosphere, and the monoalcohol can be obtained by vacuum distillation, and the unreacted raw materials are returned to the hydrogenolysis reactor to continue Conversion; the obtained monoalcohol product contains 5% methanol, 30% ethanol, 42% propanol, 10% butanol, 2% amyl alcohol, 3% hexanol, 8% isopropanol respectively according to the weight ratio.

Step 3): the monoalcohol product obtained in step 2) is added in the condensation reactor, in the presence of 5g of Ir/C catalyst prepared by impregnation method and cocatalyst o-phenanthroline 0.3g and sodium hydroxide 0.8g, Under the reaction conditions of 180°C, react for 16 hours to obtain high-valent branched alcohols. The material stream is separated by rectification under reduced pressure, and the low condensation products with carbon number less than 9 are returned to the condensation reactor for further reaction.

Step 4): The carbon number obtained in step 3) is that the high-yuan branched chain alcohol product of 9 or more is added to the deoxygenation hydrogenation reactor, and the Pt/Al ₂ O ₃ catalyst 10ml prepared by the impregnation method is filled in the reactor. The reaction was carried out under the reaction conditions of 280°C and 6MPa hydrogen atmosphere, and the injection space velocity was controlled at 0.5L/h. The product is qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS) and the GC retention time of the standard. After vacuum distillation and separation, according to weight percentage, the C9 product content is 10%, the C10 product content is 25%, and the C11 product content is 25%. The content is 18%, the content of C12 products is 20%, the content of C15 products is 20%, and the balance is products with more than C15 carbon atoms.

Example 2

The specific implementation process is the same as in Example 1, except that the catalyst added in step 1) is Ni-ZrO ₂ , and the final product is separated by vacuum distillation. According to weight percentage, the C9 product content is 5%, and the C10 product content is 5%. The C11 product content is 21%, the C12 product content is 16%, the C15 product content is 28%, and the balance is the product with carbon numbers above C15.

Example 3

The specific implementation process is the same as in Example 1, except that the catalyst added in step 2) is Ru/Al ₂ O ₃ catalyst, and after the final product is separated by vacuum distillation, according to weight percentage, the C9 product content is 7%, and the C10 The product content is 28%, the C11 product content is 15%, the C12 product content is 12%, the C15 product content is 29%, and the balance is the product with carbon number above C15.

Example 4

The specific implementation process is the same as in Example 1, except that only sorbitol is a raw material, and the catalyst added in the hydrogenolysis reactor of step 2 selects Ni-Mo/MgO catalyst for use. Percentage, the C9 product content is 8%, the C10 product content is 26%, the C11 product content is 22%, the C12 product content is 17%, the C15 product content is 22%, and the balance is the product with a carbon number above C15.

According to the preparation method of the present invention, the process of depolymerization and cracking of polyols from polysaccharides to diols, diols to monoalcohols, and further condensation of monoalcohols into small molecules and reconstruction of long-chain molecules is realized. In the cracking process, matching catalysts are used, assisted by an appropriate catalytic reaction system, to control the occurrence of excessive cracking, and to achieve high-efficiency conversion of biomass raw materials to end-product branched alkanes.

Claims (16)

1. A preparation method of bio-based aviation fuel, comprising the following steps: 1) Under a hydrogen atmosphere of 0.5-12MPa, add biomass raw materials or biomass-derived raw materials, multifunctional catalyst a and reaction solvent into the hydrogenolysis reactor to hydrocrack the raw materials to produce monoalcohols with carbon branched chains of 2 to 6 Diol and other polyol product mixtures, the reaction temperature is 160-260°C, the reaction time is 1-5 hours, and the monoalcohol and diol products are separated from the product mixture by vacuum distillation and refining reactor, Other polyol products are returned to further carry out hydrogenolysis reaction in the hydrogenolysis reactor of this step, and described reaction solvent is selected from the mixture of water, methanol and ethanol, and the weight ratio of water, methanol and ethanol is 1:0.5-0.8:0.2- 0.5; 2) Add the dibasic alcohol product, multifunctional catalyst b and reaction solvent separated in step 1) into another hydrogenolysis reactor for further hydrogenolysis, so that the dibasic alcohol product reacts to become a monoalcohol, wherein the other hydrogen The hydrogen pressure in the decomposition reactor is 0.5-12MPa, the reaction temperature is 80-215°C, and the reaction time is 1-5 hours; 3) The monoalcohols obtained in steps 1) and 2) are combined, and together with the multifunctional catalyst c, a co-catalyst selected from o-phenanthroline and sodium hydroxide and a reaction solvent, they are added into a condensation reactor to condense and prepare a carbon number of 9 to 20 carbon atoms, a branched chain higher monoalcohol product with a branch chain number of 2 to 6, wherein the reaction temperature is 80-220 ° C, and the reaction time is 2-48 hours; and 4) Under a hydrogen atmosphere of 0.5-12MPa, in a hydrodeoxygenation reactor, contact the high alcohol obtained in step 3) with the multifunctional hydrogenation catalyst d in a reaction solvent for hydrodeoxygenation, and the reaction temperature is 150-350°C , The reaction contact time is 1-20 hours, and the branched alkanes with 9 to 20 carbon atoms and 2 to 6 carbon branched chains are prepared, and the obtained material flow is separated by a rectification tower to obtain an alkane product with a boiling range in the range of aviation fuel. 2. The preparation method of bio-based aviation fuel according to claim 1, wherein the hydrogen atmosphere described in the step 1) is 4-6MPa, the reaction temperature is 180-220°C, and the reaction time is 2-3 hours; The hydrogen pressure in the step 2) is 4-8MPa, the reaction temperature is 120-180°C, and the reaction time is 2-3 hours; the reaction temperature in the step 3) is 160-200°C, and the reaction time is 10 -30 hours; the hydrogen atmosphere in the step 4) is 5-8MPa, the reaction temperature is 200-300°C, and the reaction contact time is 2-8 hours. 3. the preparation method of bio-based aviation fuel according to claim 1, wherein said preparation method further comprises the following steps: 1a) A step of pre-treating the biomass or biomass-derived raw material prior to step 1), in which the biomass or biomass-derived raw material is washed, decolorized, decolorized by ion exchange Remove substances that are toxic and harmful to the catalyst used in the subsequent steps of the process. 4. The preparation method of bio-based aviation fuel according to claim 1, wherein the weight ratio of the water, methanol and ethanol is 1:0.5:0.5. 5. The preparation method of bio-based aviation fuel according to claim 1, wherein said biomass raw material or biomass-derived raw material in said step 1) comprises straw, sawdust, molasses, paper pulp, cellulose, hemi-fiber One or more components of gluten, glucose, fructose, xylose, arabinose, sorbitol, mannitol, xylitol, arabitol and glycerin. 6. the preparation method of bio-based aviation fuel according to claim 1, wherein said step 1) said multifunctional catalyst a comprises elemental metal selected from VIII group, _IB group elemental metal, VI _B group elemental metal, Elemental metals of group VII _B and the sulfides of metals of the above-mentioned groups are supported on zeolite, silica, alumina, silica-alumina, activated carbon, and oxides of metals selected from group VIII and oxidation of group I _B metals Catalysts composed of compounds, oxides of Group VI _B metals, and oxide components of Group VII _B metals. 7. The preparation method of bio-based aviation fuel according to claim 6, wherein said step 1) said multifunctional catalyst a is selected from one of Ru, Ni, Cu, Co, Mo, Re, W One or two kinds of catalysts supported on ZnO, ZrO ₂ , alumina, zeolite and/or activated carbon. 8. the preparation method of bio-based aviation fuel according to claim 6, wherein said step 1) described multifunctional catalyst a is Ni-ZnO supported catalyst, Ni-Cu/ZrO ₂ supported catalyst, Ni- Cu/ZnO supported catalyst or Ni-W/Al ₂ O ₃ supported catalyst. 9. The preparation method of bio-based aviation fuel according to claim 1, wherein said step 2) said multifunctional catalyst b is selected from Pt, Rh, Ru, Ir, W, Re, Mo loaded on ZrO ₂ , alumina, zeolite, alumina, activated carbon prepared catalyst, the reaction solvent used in the step 2) is selected from water, dioxane, methanol, ethanol, propanol solvent. 10. The preparation method of bio-based aviation fuel according to claim 9, wherein said step 2) said multifunctional catalyst b is Rh-Mo/ZrO ₂ supported catalyst, Rh-Re/Al ₂ O ₃ supported type catalyst or Ru-W/Al ₂ O ₃ supported catalyst, the reaction solvent used in the step 2) is one or more of water, methanol and ethanol. 11. The preparation method of bio-based aviation fuel according to claim 1, wherein said step 3) said multifunctional catalyst c is selected from one or both of Pd, Pt, Rh, Ru, Ir loaded on activated carbon Prepared catalyst; the reaction solvent used in the step 3) is one or more selected from methanol, ethanol, cyclohexane, and n-hexane. 12. The preparation method of bio-based aviation fuel according to claim 11, wherein said multifunctional catalyst c in said step 3) is a catalyst prepared by loading Pd and Ir on activated carbon. 13. The preparation method of bio-based aviation fuel according to claim 1, wherein said step 4) said multifunctional catalyst d is selected from one or both of Pt, Ru, Ni, Mo, Re, W A catalyst loaded on alumina, silica-alumina, and zeolite; the reaction solvent used in the step 4) can be one or more selected from methanol, cyclohexane, and normal hexane; The branched alkanes in the step 4) are branched alkanes with 9 to 15 carbon atoms and 2 to 3 carbon chains. 14. The preparation method of bio-based aviation fuel according to claim 13, wherein the multifunctional catalyst d in the step 4) is a catalyst in which Pt-Mo is supported on silica-alumina. 15. The preparation method of bio-based aviation fuel according to claim 13, wherein said step 4) said branched chain alkane is a branched chain alkane selected from the following compounds: 16. The preparation method of bio-based aviation fuel according to claim 1, wherein said method comprises: Step 1): Pump 500ml of the saccharification solution of the biomass raw material with a sugar content concentration of 20wt% into the hydrogenolysis reactor, and simultaneously add methanol and ethanol to prevent the excessive cracking of the sugar liquid raw material as solvents in the hydrogenolysis reactor, solvent methanol, ethanol The amount of addition is 0.5 times the amount of water in the sugar solution, and then 5g of Ni-Cu-ZnO catalyst prepared by co-precipitation-gel method and reduced and activated in hydrogen at 500°C is added, under the reaction conditions of 180°C and 6MPa hydrogen atmosphere After reacting for 2 hours, the hydrogenolysis liquid is obtained, and the hydrogenolysis liquid is subjected to rectification under reduced pressure to separate low-boiling dihydric alcohols and monoalcohol products, and the high-boiling alcohols are returned to the hydrogenolysis reactor; Step 2): Adjust the dibasic alcohol obtained in step 1) to 50% aqueous solution and pump it into another hydrogenolysis reactor, and add Rh/ _SiO2 catalyst 10g prepared by the impregnation method, at 120 ℃, 8MPa hydrogen atmosphere Under the reaction condition of reaction 12h, monoalcohol can be obtained through rectification under reduced pressure, unreacted raw material is returned to hydrogenolysis reactor to continue conversion; The obtained monoalcohol product contains 5% methanol, 30% ethanol, 42 % Propanol, 10% Butanol, 2% Pentanol, 3% Hexanol, 8% Isopropanol; Step 3): the monoalcohol product obtained in step 2) is added in the condensation reactor, in the presence of 5g of Ir/C catalyst prepared by impregnation method and cocatalyst o-phenanthroline 0.3g and sodium hydroxide 0.8g, React under the reaction conditions of 180°C for 16 hours to produce high-valent branched chain alcohols. The material flow is separated by vacuum distillation, and the low-condensation products with less than 9 carbon atoms are returned to the condensation reactor for further reaction; Step 4): The carbon number obtained in step 3) is that the high-yuan branched chain alcohol product of 9 or more is added to the deoxygenation hydrogenation reactor, and the Pt/Al ₂ O ₃ catalyst 10ml prepared by the impregnation method is filled in the reactor. React under the reaction conditions of 280°C and 6MPa hydrogen atmosphere, control the injection space velocity at 0.5L/h, and separate the products through vacuum distillation. According to the weight percentage, the C9 product content is 10%, the C10 product content is 25%, and the C11 product content is 25%. The product content is 18%, the C12 product content is 20%, the C15 product content is 20%, and the balance is the product with more than C15 carbon atoms.