A method for preparing sustainable aviation fuel from biomass straw

Abstract

The present invention provides a method for preparing sustainable aviation fuel from biomass straw. First, the biomass straw is made into syngas, then the syngas is made into Fischer-Tropsch oil, and then the Fischer-Tropsch oil is hydrocracked and isomerized to make aviation fuel. The operation steps of hydrocracking and isomerizing the Fischer-Tropsch oil to make aviation fuel are as follows: S1. The Fischer-Tropsch oil and hydrogen are mixed and enter the hydrorefining reaction zone. Under hydrorefining conditions, they are contacted with a composite supported catalyst to obtain hydrorefined oil, which is fractionated to obtain a kerosene fraction a1, a diesel fraction b1, and a tail oil fraction c1; S2. The tail oil fraction c1 enters the hydrocracking and isomerization reaction zone. Under hydrocracking and isomerization conditions, it is contacted with a composite supported catalyst to obtain hydrocracked oil, which is fractionated to obtain a kerosene fraction a2, a diesel fraction b2, and a tail oil fraction c2; The tail oil fraction c2 is recycled to the hydrocracking and isomerization reaction zone; S3. The kerosene fraction a1 and the kerosene fraction a2 are mixed to obtain aviation fuel. The present invention can significantly improve the yield of aviation fuel.

Description

Technical Field

[0001] The present invention belongs to the technical field of aviation fuels, and particularly relates to a method for preparing sustainable aviation fuels based on biomass straws. Background Art

[0002] As a renewable resource, under the background of environmental protection and sustainable development, the technology of converting biomass straws into aviation fuels is particularly important. This technology can not only reduce the dependence on fossil fuels, lower carbon emissions, but also effectively utilize agricultural waste, with significant environmental and economic benefits.

[0003] There is an existing process for preparing aviation fuels from biomass straws, which mainly consists of three steps in sequence: converting biomass straws into syngas, converting syngas into Fischer-Tropsch oil, and subjecting Fischer-Tropsch oil to hydrocracking and isomerization to produce aviation fuels. Among them, the first step involves converting biomass into syngas rich in carbon monoxide (CO), carbon dioxide (CO2) and hydrogen (H2) through a gasification reaction; this technology has been widely studied and there are mature application examples. The second step is a process of synthesizing liquid hydrocarbons or hydrocarbons from syngas as raw materials under the action of a catalyst and appropriate conditions. This technology was first developed by German chemists Franz Fischer and Hans Tropsch in 1925.

[0004] The third step of hydrocracking is a process of converting heavy oil products into light oil products. For the production of aviation fuels, specific isomerization steps are required to meet the low-temperature performance requirements of aviation fuels. How to precisely control the hydrocracking and isomerization processes to obtain aviation fuels that meet the specification requirements while maintaining a high yield is a problem that needs to be solved. Summary of the Invention

[0005] To solve the problems in the background art, the present invention provides a method for preparing sustainable aviation fuels based on biomass straws, which can significantly improve the yield of aviation fuels.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing sustainable aviation fuels based on biomass straws, first converting biomass straws into syngas, then converting syngas into Fischer-Tropsch oil, and then subjecting Fischer-Tropsch oil to hydrocracking and isomerization to produce aviation fuels. The operating steps of subjecting Fischer-Tropsch oil to hydrocracking and isomerization to produce aviation fuels are as follows:

[0008] S1. After mixing Fischer-Tropsch oil and hydrogen, they enter a hydrofining reaction zone, and under hydrofining conditions, contact with a composite supported catalyst to obtain hydrofined oil; fractionate the hydrofined oil to obtain fractions including a kerosene fraction a1, a diesel fraction b1 and a tail oil fraction c1;

[0009] S2. The tail oil fraction c1 enters the hydrocracking isomerization reaction zone and contacts with the composite supported catalyst under hydrocracking isomerization conditions to obtain hydrocracked oil. The hydrocracked oil is fractionated to obtain fractions including a kerosene fraction a2, a diesel fraction b2, and a tail oil fraction c2. The tail oil fraction c2 is recycled to the hydrocracking isomerization reaction zone to continue the hydrocracking isomerization reaction.

[0010] S3. Mix the kerosene fraction a1 obtained in S1 and the kerosene fraction a2 obtained in S2 to obtain aviation fuel.

[0011] Furthermore, in S1 and S2, the preparation method of the composite supported catalyst is as follows:

[0012] A1. Mix modified nanoaluminum silicate, aluminum oxide monohydrate, and ammonium nitrate in a mass ratio of 1:(1 - 2):(2 - 3), extrude into strips, air-dry naturally, dry at 120°C for 2 h, and calcine at 550°C for 2 h to obtain a composite support.

[0013] A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:(3 - 5) to obtain a mixture.

[0014] A3. Immerse the mixture obtained in A2 on the composite support obtained in A1. The mass ratio of the mixture to the composite support is 1:(2 - 3). Then, dry it in an oven at 120°C for 4 h, and then calcine at 500°C for 2 h to obtain the composite supported catalyst.

[0015] Furthermore, in A1, the preparation method of the modified nanoaluminum silicate is as follows:

[0016] A11. Take 7 - 9 parts by weight of stearic acid, heat it to melt, add 5 parts of aluminum nitrate nonahydrate, stir to dissolve, and cool to 90°C to obtain a solution. Take 0.2 parts of cobalt sulfate heptahydrate, dissolve it in 0.5 parts of water to obtain a cobalt sulfate solution. Take 3 parts of tetraethyl orthosilicate, mix it with the solution and the cobalt sulfate solution, and naturally cool to room temperature to obtain a gel.

[0017] A12. Calcinate the gel obtained in A11 at 500°C for 3 - 5 h to obtain nano - raw powder, and then raise the temperature to 700 - 900°C and continue to calcine for 2 - 3 h to obtain cobalt - doped aluminum silicate.

[0018] A13. Immerse the cobalt - doped aluminum silicate obtained in A12 in an organosilane. After 30 - 50 min, filter it out and dry it at 35 - 40°C for 1 - 2 h to obtain the modified nanoaluminum silicate.

[0019] Furthermore, in A13, the organosilane includes 3 - glycidoxypropyltrimethoxysilane and / or 3 - aminopropyltriethoxysilane.

[0020] Further, in S1, the hydrofining conditions are as follows: hydrogen partial pressure is 2.0 - 15.0 MPa, reaction temperature is 250 - 400 °C, hydrogen-oil volume ratio is (100 - 1000):1, and volume space velocity is 0.5 - 10.0 h -1 .

[0021] Further, in S1, the hydrofining conditions are as follows: hydrogen partial pressure is 10.0 MPa, reaction temperature is 315 °C, and hydrogen-oil volume ratio is 450:1.

[0022] Further, in S2, the hydrocracking and isomerization conditions are as follows: hydrogen partial pressure is 2.0 - 15.0 MPa, reaction temperature is 300 - 450 °C, hydrogen-oil volume ratio is (100 - 1500):1, and volume space velocity is 0.5 - 5.0 h -1 .

[0023] Further, in S2, the hydrocracking and isomerization conditions are as follows: hydrogen partial pressure is 10.0 MPa, reaction temperature is 370 °C, and hydrogen-oil volume ratio is 800:1.

[0024] Further, in S1, the cut-off point temperature between the kerosene fraction a1 and the diesel fraction b1 is 200 - 300 °C; in S2, the cut-off point temperature between the kerosene fraction a2 and the diesel fraction b2 is 200 - 300 °C.

[0025] The present application has the following beneficial effects:

[0026] 1. The present invention uses a composite supported catalyst. There is a complex synergistic effect among the raw material components of the catalyst, namely modified nanoaluminosilicate, alumina monohydrate, and ammonium nitrate. These effects together determine the physical and chemical properties of the composite support and the ultimately excellent catalytic performance. The introduced nickel and tungsten components as active centers have excellent hydrogenation and isomerization capabilities, which are crucial for improving the efficiency of the hydrocracking and isomerization reaction. These metal components are highly dispersed on the composite support with a high specific surface area and excellent pore structure, enabling the catalyst to maintain high activity while also having good selectivity and stability, significantly increasing the conversion rate of the reactants, and enabling more raw materials (Fischer-Tropsch oil) to be effectively converted into the target product (aviation fuel).

[0027] 2. In the preparation of the modified nanoaluminosilicate, cobalt doping can enhance the mechanical strength and thermal stability of the aluminosilicate, while the surface modification with 3-glycidoxypropyltrimethoxysilane helps to improve its dispersibility and reactivity in the organic reaction environment. This modified nanoaluminosilicate as a catalyst support provides a larger specific surface area and better pore structure for the active components, thereby promoting the efficiency of the catalytic reaction and increasing the yield of the target product.

[0028] 3. The surface modification of modified nanoaluminum silicate can enhance its bonding force with aluminum hydroxide monohydrate, thereby maintaining the structural integrity and catalytic activity during high-temperature calcination, and helping to improve the dispersion of nanoparticles in the aluminum hydroxide monohydrate matrix and avoid agglomeration, which is crucial for maintaining the high activity of the catalyst; ammonium nitrate decomposes to produce gas during calcination, which helps to better form a porous structure, further increasing the specific surface area of the catalyst and providing more active sites for catalytic reactions; during the decomposition of ammonium nitrate, aluminum hydroxide monohydrate works synergistically with it to maintain structural integrity and ensure that the catalyst still has high mechanical strength after thermal decomposition, providing a strong guarantee for maintaining the performance of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a comparison trend chart of the yields of Fischer-Tropsch oil hydrocracking and isomerization to aviation fuel in Examples 1-5 and Comparative Examples 1-7 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following further describes the present application in detail with reference to embodiments. In the embodiments and comparative examples, due to the differences in the addition of components, if phenomena such as extrusion not forming or powdering after calcination occur, the tests are carried out normally in sequence.

[0031] The raw materials of the embodiments and comparative examples of the present application are all ordinary commercially available products unless otherwise specified.

[0032] Example 1: A method for preparing sustainable aviation fuel based on biomass straw. First, the biomass straw is made into syngas, then the syngas is made into Fischer-Tropsch oil, and then the Fischer-Tropsch oil is hydrocracked and isomerized to make aviation fuel. The operating steps for hydrocracking and isomerizing Fischer-Tropsch oil to make aviation fuel are as follows:

[0033] S1. After the Fischer-Tropsch oil and hydrogen are mixed, they enter a hydrofining reactor and contact with a composite supported catalyst under hydrofining conditions to obtain an effluent, which is hydrofined oil; the hydrofining conditions are: hydrogen partial pressure 10.0 MPa, reaction temperature 315 °C, and hydrogen-oil volume ratio 450:1.

[0034] The hydrofined oil enters Fractionating Tower 1 for fractionation and is cut into naphtha fraction d1, kerosene fraction a1, diesel fraction b1, and tail fraction c1. The temperature range for fractionating the fractionating oil in Fractionating Tower 1 is: naphtha fraction d1 is < 130 °C, kerosene fraction a1 is 130 - 240 °C, diesel fraction b1 is 240 - 350 °C, and tail oil fraction c1 is > 350 °C.

[0035] S2. The tail oil fraction c1 and the unreacted heavy fraction in the second fractionation tower enter the hydrocracking isomerization reactor together, and hydrogen is supplemented at the same time. Under the hydrocracking isomerization conditions, it contacts with the composite supported catalyst to obtain an effluent, which is hydrocracked oil. The hydrocracking isomerization conditions are: hydrogen partial pressure 10.0 MPa, reaction temperature 370 °C, and hydrogen-oil volume ratio 800:1.

[0036] The hydrocracked oil enters the second fractionation tower for fractionation, and is cut into naphtha fraction d2, kerosene fraction a2, diesel fraction b2 and tail oil fraction c2. The temperature range for fractionating the fractionated oil in the second fractionation tower is: naphtha fraction d2 < 130 °C, kerosene fraction a2 130 - 240 °C, diesel fraction b2 240 - 350 °C, and tail oil fraction c2 > 350 °C.

[0037] The tail oil fraction c2 is the unreacted heavy fraction, which is recycled and enters the hydroisomerization cracking reactor together with the tail oil fraction c1 for continuous cracking to achieve full conversion of the heavy fraction.

[0038] S3. Mix the kerosene fraction a1 obtained in S1 and the kerosene fraction a2 obtained in S2 to obtain aviation fuel.

[0039] The same composite supported catalyst is used in S1 and S2, and the preparation method of the composite supported catalyst is as follows:

[0040] A1. Mix modified nanoaluminum silicate, aluminum oxide monohydrate and ammonium nitrate in a mass ratio of 1:1.5:2.5, extrude into strips, air dry naturally, dry at 120 °C for 2 h, and calcine at 550 °C for 2 h to obtain a composite support;

[0041] A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:4 to obtain a mixture;

[0042] A3. Impregnate the mixture obtained in A2 on the composite support obtained in A1. The mass ratio of the mixture to the composite support is 1:2.5. Then dry it in an oven at 120 °C for 4 h, and then calcine it at 500 °C for 2 h to obtain the composite supported catalyst.

[0043] In A1, the preparation method of the modified nanoaluminum silicate is as follows:

[0044] A11. By weight, take 8 parts of stearic acid, heat it to melt, add 5 parts of aluminum nitrate nonahydrate, stir and dissolve, cool down to 90 °C to obtain a solution; take 0.2 part of cobalt sulfate heptahydrate, dissolve it in 0.5 part of water to obtain a cobalt sulfate solution; take 3 parts of ethyl silicate, mix it with the solution and the cobalt sulfate solution, and naturally cool to room temperature to obtain a gel;

[0045] A12. Calcinate the gel obtained in A11 at 500 °C for 4 h to obtain the nano raw powder, then raise the temperature to 800 °C and continue to calcine for 2.5 h to obtain cobalt-doped aluminum silicate;

[0046] A13. Immerse the cobalt-doped aluminum silicate obtained in A12 in 3-glycidoxypropyltrimethoxysilane. After 40 min, filter it out and dry it at 38 °C for 1.5 h to obtain the modified nano aluminum silicate.

[0047] Example 2: The difference between this example and Example 1 is only that: in S1, the hydrofining conditions are: hydrogen partial pressure 2.0 MPa, reaction temperature 250 °C, hydrogen-oil volume ratio 100:1. In S2, the hydrocracking and isomerization conditions are: hydrogen partial pressure 2.0 MPa, reaction temperature 300 °C, hydrogen-oil volume ratio 100:1.

[0048] Example 3: The difference between this example and Example 1 is only that: in S1, the hydrofining conditions are: hydrogen partial pressure 15.0 MPa, reaction temperature 400 °C, hydrogen-oil volume ratio 1000:1. In S2, the hydrocracking and isomerization conditions are: hydrogen partial pressure 15.0 MPa, reaction temperature 450 °C, hydrogen-oil volume ratio 1500:1.

[0049] Example 4: The difference between this example and Example 1 is only that the preparation method of the composite supported catalyst is as follows:

[0050] A1. Mix modified nano aluminum silicate, aluminum oxide monohydrate and ammonium nitrate in a mass ratio of 1:1:2, extrude into strips, air dry naturally, dry at 120 °C for 2 h, and calcine at 550 °C for 2 h to obtain a composite support;

[0051] A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:3 to obtain a mixture;

[0052] A3. Immerse the mixture obtained in A2 on the composite support obtained in A1. The mass ratio of the mixture to the composite support is 1:2, then dry it in an oven at 120 °C for 4 h, and then calcine it at 500 °C for 2 h to obtain the composite supported catalyst.

[0053] The preparation method of the modified nano aluminum silicate is the same as that in Example 1.

[0054] Example 5: The difference between this example and Example 1 is only that the preparation method of the composite supported catalyst is as follows:

[0055] A1. Mix modified nano aluminum silicate, aluminum oxide monohydrate and ammonium nitrate in a mass ratio of 1:2:3, extrude into strips, air dry naturally, dry at 120 °C for 2 h, and calcine at 550 °C for 2 h to obtain a composite support;

[0056] A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:5 to obtain a mixture;

[0057] A3. Immerse the mixture obtained in A2 on the composite support obtained in A1. The mass ratio of the mixture to the composite support is 1:3. Then, dry it in an oven at 120 °C for 4 h, and then calcine it at 500 °C for 2 h to obtain the composite-supported catalyst.

[0058] The preparation method of the modified nanoaluminosilicate is the same as that in Example 1.

[0059] Comparative Example 1: The difference between this comparative example and Example 1 is only that: in the preparation of the modified nanoaluminosilicate, cobalt sulfate heptahydrate is deleted and cobalt doping is not carried out.

[0060] Specifically, the preparation method of the modified nanoaluminosilicate is as follows:

[0061] A11. By weight, take 8 parts of stearic acid, heat it to melt, add 5 parts of aluminum nitrate nonahydrate, stir to dissolve, and cool down to 90 °C to obtain a solution; take 3 parts of tetraethyl orthosilicate, mix it with the solution, and naturally cool it to room temperature to obtain a gel.

[0062] A12. Calcinate the gel obtained in A11 at 500 °C for 4 h to obtain nano raw powder, then raise the temperature to 800 °C and continue to calcine for 2.5 h to obtain aluminosilicate.

[0063] A13. Immerse the aluminosilicate obtained in A12 in 3-glycidoxypropyltrimethoxysilane. After 40 min, filter it out and dry it at 38 °C for 1.5 h to obtain the modified nanoaluminosilicate.

[0064] Comparative Example 2: The difference between this comparative example and Example 1 is only that: the modified nanoaluminosilicate is replaced by cobalt-doped aluminosilicate, that is, organic silane is deleted and silane modification is not carried out.

[0065] Specifically, the preparation method of the cobalt-doped aluminosilicate is as follows:

[0066] A11. By weight, take 8 parts of stearic acid, heat it to melt, add 5 parts of aluminum nitrate nonahydrate, stir to dissolve, and cool down to 90 °C to obtain a solution; take 0.2 part of cobalt sulfate heptahydrate, dissolve it in 0.5 part of water to obtain a cobalt sulfate solution; take 3 parts of tetraethyl orthosilicate, mix it with the solution and the cobalt sulfate solution, and naturally cool it to room temperature to obtain a gel.

[0067] A12. Calcinate the gel obtained in A11 at 500 °C for 4 h to obtain nano raw powder, then raise the temperature to 800 °C and continue to calcine for 2.5 h to obtain the cobalt-doped aluminosilicate.

[0068] Comparative Example 3: The difference between this comparative example and Example 1 is only that: the modified nanoaluminosilicate is replaced by aluminosilicate, that is, cobalt sulfate heptahydrate is deleted, cobalt doping is not carried out, and organic silane is deleted and silane modification is not carried out.

[0069] Specifically, the preparation method of aluminum silicate is as follows:

[0070] A11. By weight, take 8 parts of stearic acid, heat and melt it, then add 5 parts of aluminum nitrate nonahydrate, stir and dissolve, cool down to 90 °C to obtain a solution; take 3 parts of ethyl silicate, mix it with the solution, and naturally cool to room temperature to obtain a gel;

[0071] A12. Calcinate the gel obtained in A11 at 500 °C for 4 h to obtain nano raw powder, then raise the temperature to 800 °C and continue to calcinate for 2.5 h to obtain aluminum silicate.

[0072] Comparative Example 4: The difference between this comparative example and Example 1 is only that: in the preparation of the composite supported catalyst, aluminum oxide monohydrate is deleted.

[0073] Specifically, the preparation method of the composite supported catalyst is as follows:

[0074] A1. Mix the modified nano aluminum silicate and ammonium nitrate in a mass ratio of 1:2.5, extrude into strips, air dry naturally, dry at 120 °C for 2 h, and calcine at 550 °C for 2 h to obtain a composite support;

[0075] A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:4 to obtain a mixture;

[0076] A3. Immerse the mixture obtained in A2 on the composite support obtained in A1, the mass ratio of the mixture to the composite support is 1:2.5, then dry in an oven at 120 °C for 4 h, and then calcine at 500 °C for 2 h to obtain the composite supported catalyst.

[0077] Comparative Example 5: The difference between this comparative example and Example 1 is only that: in the preparation of the composite supported catalyst, ammonium nitrate is deleted.

[0078] Specifically, the preparation method of the composite supported catalyst is as follows:

[0079] A1. Mix the modified nano aluminum silicate and aluminum oxide monohydrate in a mass ratio of 1:1.5, extrude into strips, air dry naturally, dry at 120 °C for 2 h, and calcine at 550 °C for 2 h to obtain a composite support;

[0080] A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:4 to obtain a mixture;

[0081] A3. Immerse the mixture obtained in A2 on the composite support obtained in A1, the mass ratio of the mixture to the composite support is 1:2.5, then dry in an oven at 120 °C for 4 h, and then calcine at 500 °C for 2 h to obtain the composite supported catalyst.

[0082] Comparative Example 6: The difference between this comparative example and Example 1 is only that: in the preparation of the composite supported catalyst, aluminum hydroxide monohydrate and ammonium nitrate are deleted.

[0083] Specifically, the preparation method of the composite supported catalyst is as follows:

[0084] A1. Extrude the modified nanoaluminosilicate, air-dry it naturally, dry it at 120 °C for 2 h, and calcine it at 550 °C for 2 h to obtain the carrier;

[0085] A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:4 to obtain a mixture;

[0086] A3. Immerse the mixture obtained in A2 on the carrier obtained in A1, the mass ratio of the mixture to the carrier is 1:2.5, then dry it in an oven at 120 °C for 4 h, and then calcine it at 500 °C for 2 h to obtain the composite supported catalyst.

[0087] Comparative Example 7: The difference between this comparative example and Example 1 is only that: the modified nanoaluminosilicate is replaced by cobalt-doped aluminosilicate, that is, organosilane is deleted and silane modification is not carried out; and, in the preparation of the composite supported catalyst, aluminum hydroxide monohydrate is deleted.

[0088] Specifically, the preparation method of cobalt-doped aluminosilicate is as follows:

[0089] A11. By weight, take 8 parts of stearic acid, heat and melt it, then add 5 parts of aluminum nitrate nonahydrate, stir and dissolve it, cool it down to 90 °C to obtain a solution; take 0.2 parts of cobalt sulfate heptahydrate, dissolve it in 0.5 parts of water to obtain a cobalt sulfate solution; take 3 parts of ethyl silicate, mix it with the solution and the cobalt sulfate solution, and naturally cool it to room temperature to obtain a gel;

[0090] A12. Calcinate the gel obtained in A11 at 500 °C for 4 h to obtain nano raw powder, then raise the temperature to 800 °C and continue to calcine for 2.5 h to obtain cobalt-doped aluminosilicate.

[0091] The preparation method of the composite supported catalyst is as follows:

[0092] A1. Mix cobalt-doped aluminosilicate and ammonium nitrate in a mass ratio of 1:2.5, extrude it, air-dry it naturally, dry it at 120 °C for 2 h, and calcine it at 550 °C for 2 h to obtain a composite carrier;

[0093] A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:4 to obtain a mixture;

[0094] A3. Immerse the mixture obtained in A2 on the composite carrier obtained in A1, the mass ratio of the mixture to the composite carrier is 1:2.5, then dry it in an oven at 120 °C for 4 h, and then calcine it at 500 °C for 2 h to obtain the composite supported catalyst.

[0095] Test Example 1: Test Subjects: Examples 1-5 and Comparative Examples 1-6.

[0096] Test Items: Statistically compare the yields of aviation fuel (a mixture of kerosene fraction a1 + kerosene fraction a2) for each test subject.

[0097] Yield of aviation fuel (%) = (mass of kerosene fraction a1 + mass of kerosene fraction a2) / mass of Fischer-Tropsch oil feed * 100%.

[0098] Test Results: See Table 1.

[0099] Table 1. Aviation fuel yield data for Examples 1-5 and Comparative Examples 1-6

[0100] Distillation range / °C Density / g / mL Yield of aviation fuel / % Example 1 130-240 0.7523 49.5 Example 2 130-240 0.7519 49.2 Example 3 130-240 0.7511 48.8 Example 4 130-240 0.7534 48.6 Example 5 130-240 0.7527 48.8 Comparative Example 1 130-240 0.7502 42.7 Comparative Example 2 130-240 0.7509 44.4 Comparative Example 3 130-240 0.7496 39.6 Comparative Example 4 130-240 0.7495 43.2 Comparative Example 5 130-240 0.7513 37.5 Comparative Example 6 130-240 0.7505 35.3 Comparative Example 7 130-240 0.7508 40.7

[0101] Result Analysis: Analyze Examples 1-5 and combine with the data in Table 1 and Figure 1 It can be seen that the aviation fuel of the present invention has a high and stable yield, which can reach more than 48.6%; in the hydrofining and hydrocracking isomerization processes of Fischer-Tropsch oil of the present invention, the composite supported catalyst used has good catalytic effect, which is beneficial to the preparation of aviation fuel.

[0102] Analyze Example 1 and Comparative Examples 1-3 and combine with the data in Table 1 and Figure 1 It can be seen that in the hydrofining and hydrocracking isomerization processes of Fischer-Tropsch oil of the present invention, a composite supported catalyst is used. In the preparation process of this catalyst, raw material modified nanoaluminum silicate is used, and cobaltous sulfate heptahydrate is added in the preparation process of modified nanoaluminum silicate to introduce cobalt doping, which can improve the yield of the finally prepared aviation fuel; 3-glycidoxypropyltrimethoxysilane is added in the preparation process of modified nanoaluminum silicate for silane modification, which can also improve the yield of the finally prepared aviation fuel; moreover, the two act synergistically and can synergistically improve the yield of the finally prepared aviation fuel.

[0103] Analyze Example 1 and Comparative Examples 4-6 and combine with the data in Table 1 and Figure 1 It can be seen that in the hydrofining and hydrocracking isomerization processes of Fischer-Tropsch oil of the present invention, a composite supported catalyst is used. In the preparation process of this catalyst, the addition of aluminum oxide monohydrate as a raw material component can improve the yield of the finally prepared aviation fuel; the addition of ammonium nitrate as a raw material component can also improve the yield of the finally prepared aviation fuel; moreover, there is a synergistic effect between aluminum oxide monohydrate and ammonium nitrate, which can synergistically improve the yield of the finally prepared aviation fuel.

[0104] Analyze Example 1 and Comparative Examples 2, 4, 7 and combine with the data in Table 1 and Figure 1It can be seen that during the preparation of the catalyst, 3-glycidoxypropyltrimethoxysilane is added in the preparation of the raw material modified nanoaluminum silicate for silane modification; and the addition of aluminum oxide monohydrate as a raw material component; there is a synergistic effect between the two, which can synergistically improve the yield of the finally prepared aviation fuel.

[0105] In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0106] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing sustainable aviation fuel based on biomass straw, firstly converting biomass straw into synthesis gas, then converting the synthesis gas into Fischer-Tropsch oil, and then hydrocracking and isomerizing the Fischer-Tropsch oil into aviation fuel, characterized in that: The operating steps of hydrocracking and isomerization of Fischer-Tropsch oil to produce aviation fuel are as follows: S1, Fischer-Tropsch oil and hydrogen are mixed and then enter the hydrorefining reaction zone, and contact with the composite supported catalyst under hydrorefining conditions to obtain hydrorefined oil; the hydrorefined oil is fractionated to obtain fractions including kerosene fraction a1, diesel fraction b1 and tail oil fraction c1; S2, tail oil fraction c1 enters the hydrocracking isomerization reaction zone, contacts with the composite supported catalyst under the hydrocracking isomerization conditions, and obtains hydrocracking oil; the hydrocracking oil is fractionated to obtain fractions including kerosene fraction a2, diesel fraction b2 and tail oil fraction c2; the tail oil fraction c2 is circulated back to the hydrocracking isomerization reaction zone to continue the hydrocracking isomerization reaction; S3, mixing the kerosene fraction a1 obtained in S1 and the kerosene fraction a2 obtained in S2 to obtain aviation fuel; In S1 and S2, the preparation method of the composite supported catalyst is as follows: A1. Modified nano aluminum silicate, aluminum oxide monohydrate and ammonium nitrate were mixed in a mass ratio of 1: (1-2): (2-3), extruded, naturally dried, dried at 120°C for 2 h, and calcined at 550°C for 2 h to obtain a composite carrier; A2. Mix nickel nitrate and ammonium metatungstate in a mass ratio of 1:(3-5) to obtain a mixture; A3, impregnating the mixture obtained in A2 on the composite support obtained in A1, wherein the mass ratio of the mixture to the composite support is 1:(2-3), and then drying in an oven at 120°C for 4 h, and then calcining at 500°C for 2 h, to obtain a composite supported catalyst; In A1, the preparation method of the modified nano aluminum silicate is as follows: A11. Take 7-9 parts of stearic acid by weight, heat and melt, add 5 parts of aluminum nitrate nonahydrate, stir and dissolve, cool to 90°C to obtain a solution; take 0.2 parts of cobalt sulfate heptahydrate, dissolve in 0.5 parts of water to obtain a cobalt sulfate solution; take 3 parts of ethyl silicate, mix with the solution and the cobalt sulfate solution, and cool naturally to room temperature to obtain a gel; A12, calcining the gel obtained in A11 at 500°C for 3-5h to obtain nano raw powder, then raising the temperature to 700-900°C and continuing calcining for 2-3h to obtain cobalt-doped aluminum silicate; A13. Soak the cobalt-doped aluminum silicate obtained in A12 in organic silane for 30-50 minutes, filter it out, and dry it at 35-40°C for 1-2 hours to obtain modified nano aluminum silicate.

2. The method for preparing sustainable aviation fuel based on biomass straw according to claim 1, characterized in that: In A13, the organosilane includes 3-glycidoxypropyltrimethoxysilane and / or 3-aminopropyltriethoxysilane.

3. The method for preparing sustainable aviation fuel based on biomass straw according to claim 1, characterized in that: In S1, the hydrofining conditions are: hydrogen partial pressure 2.0-15.0MPa, reaction temperature 250-400°C, hydrogen-oil volume ratio (100-1000): 1, volume space velocity 0.5-10.0h -1 .

4. The method for preparing sustainable aviation fuel based on biomass straw according to claim 3, characterized in that: In S1, the hydrotreating conditions are: hydrogen partial pressure 10.0 MPa, reaction temperature 315°C, hydrogen-to-oil volume ratio 450:

1.

5. The method for preparing sustainable aviation fuel based on biomass straw according to claim 1, characterized in that: In S2, the hydrocracking isomerization conditions are: hydrogen partial pressure 2.0-15.0 MPa, reaction temperature 300-450°C, hydrogen-oil volume ratio (100-1500): 1, volume space velocity 0.5-5.0 h -1 .

6. The method for preparing sustainable aviation fuel based on biomass straw according to claim 5, characterized in that: In S2, the hydrocracking isomerization conditions are: hydrogen partial pressure 10.0 MPa, reaction temperature 370°C, hydrogen-to-oil volume ratio 800:

1.

7. The method for preparing sustainable aviation fuel based on biomass straw according to claim 1, characterized in that: In S1, the cutting point temperature of the kerosene fraction a1 and the diesel fraction b1 is 200-300°C; in S2, the cutting point temperature of the kerosene fraction a2 and the diesel fraction b2 is 200-300°C.

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