Process for preparing aviation kerosene from methanol
By using ZSM-5 molecular sieve catalyst to process methanol to olefins, oligomerization, and hydrogenation fractionation, aviation kerosene can be directly obtained, solving the problems of high equipment investment and high energy consumption in existing technologies, and realizing an economical and efficient methanol-to-aviation kerosene process.
Patent Information
- Application Number
- CN202410757900.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-13
- Publication Date
- 2025-12-16
AI Technical Summary
Existing direct methanol-to-jet fuel technology requires blending with petroleum-based oils and involves cryogenic separation and methanol distillation, resulting in high equipment investment and energy consumption, making it difficult to meet the production requirements of aviation kerosene.
The methanol-to-olefins unit uses ZSM-5 molecular sieve catalyst to react under specific conditions. After separating aromatics, it directly undergoes oligomerization and hydrogenation fractionation, avoiding cryogenic separation and blending processes, and directly obtains aviation kerosene.
This technology eliminates the need for blending with petroleum-based oils, reduces equipment investment and energy consumption, and improves the economics and carbon-based total yield of methanol-to-aviation kerosene.
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Figure CN121136729A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of methanol-based aviation kerosene technology, and more specifically to a process for preparing methanol-based aviation kerosene. Background Technology
[0002] In recent years, with the rapid development of new energy technologies in my country, the price of green electricity has dropped significantly, leading to a reduction in the cost of hydrogen production through water electrolysis. The price of green hydrogen will eventually be on par with that of hydrogen produced from traditional fossil fuels. Using green hydrogen and carbon dioxide as raw materials to produce methanol can both achieve CO2 conversion and utilization and solve the storage and transportation problems of green hydrogen. Methanol, as a basic chemical raw material, has significant implications for high-value utilization. Sustainable aviation fuel (SAF) is key to achieving net-zero carbon emissions in the global aviation industry. Compared to traditional aviation fuel, SAF can reduce greenhouse gas emissions by 88%. SAF can be blended with traditional aviation fuel and used as a direct substitute for petroleum-based aviation fuel without any modifications to aircraft technology or fuel infrastructure. The global market size for SAF is projected to exceed 18 million tons by 2030, valued at tens of billions of US dollars. Currently priced at around 20,000 yuan per ton, it has a very promising market prospect.
[0003] Aviation kerosene is characterized by a distillation range between naphtha and diesel, and a relatively concentrated carbon number (C8-C16). To ensure the safety of aircraft engines, it requires a very high freezing point (not exceeding -40°C), and also contains 8-20% aromatics. Currently, SAF production methods include the oil and fat hydrogenation route, the ATJ (Automatic Air Jet) route, and the biomass gasification-Fischer-Tropsch route, all of which have obtained international certification. The aviation kerosene fractions obtained from these routes are mainly composed of straight-chain / branched alkanes, which do not meet aviation kerosene standards and must be blended with petroleum-based products. In May 2023, Honeywell announced the launch of UOP eFining, a mature solution for producing low-carbon, sustainable aviation fuel. TM The technology involves synthesizing methanol from green hydrogen and carbon dioxide, which can be further converted into various sustainable fuels, including SAF, gasoline, and diesel. This route converts methanol into C2-C5 olefins via an MTO process. A simplified cryogenic separation process separates a mixture of ethylene and C3-C5 olefins. The ethylene and C3-C5 olefins are then oligomerized into jet fuel components, which are hydrogenated and fractionated to obtain the jet fuel product. Since no aromatics are produced in the process, it also needs to be blended with petroleum-based jet fuel products before use. This method received international certification at the end of 2023.
[0004] Currently, the technology for direct conversion of methanol into jet fuel is in the early stages of research and development. Only a few companies have announced the completion of technology development, but there are no industrial demonstration cases yet. Summary of the Invention
[0005] This invention provides a process for preparing methanol-based aviation kerosene. The process can convert methanol into olefins / aromatics, followed by olefin oligomerization, hydrogenation, and fractionation. Aviation kerosene can be obtained without blending with petroleum-based oils. Furthermore, this process does not involve cryogenic separation or methanol distillation, which can save on equipment investment and process energy consumption, thereby improving the economics of methanol-based aviation kerosene.
[0006] To achieve its objective, the present invention provides the following technical solution:
[0007] This invention provides a process for preparing methanol-based aviation kerosene, comprising the following steps:
[0008] (1) Aqueous crude methanol with a methanol concentration of 50-64wt% is reacted in the methanol-to-olefins unit in the presence of a first catalyst, and the aromatics in the resulting reaction product are separated to obtain aromatic materials and materials rich in C2-C5 olefins.
[0009] The reaction conditions for the methanol-to-olefins unit include: a temperature of 350-420℃, a pressure of 0.7-1.2 MPa, and a weight hourly space velocity of 1-4 h⁻¹. -1 ;
[0010] The active component of the first catalyst includes ZSM-5 molecular sieve, and the silica-alumina ratio of the ZSM-5 molecular sieve is 80-120.
[0011] (2) The material rich in C2-C5 olefins is fed into the olefin oligomerization unit for oligomerization reaction to obtain oligomer products;
[0012] (3) The oligomer product described in step (2) is mixed with the aromatic material to obtain a mixture. The mixture is then subjected to hydrogenation and fractionated to obtain aviation kerosene.
[0013] Furthermore, in step (1), the crude methanol is an aqueous methanol solution;
[0014] Preferably, the crude methanol is obtained during the process of producing methanol by CO2 hydrogenation.
[0015] Preferably, the content of the active component in the first catalyst is 70-80 wt%.
[0016] The first catalyst further includes a support, and preferably also includes an auxiliary agent, wherein the auxiliary agent includes CaO, and the content of the auxiliary agent in the first catalyst is 1-10 wt%.
[0017] Preferably, the support for the first catalyst is activated alumina.
[0018] Preferably, in the first catalyst, the content of the auxiliary agent is 3-10%, more preferably 3-7%; the silicon-aluminum ratio of the ZSM-5 molecular sieve is 90-120, more preferably 90-110.
[0019] Preferably, in the reaction product of step (1), the C2-C5 olefin content is 75-96 wt%, the ethylene content is ≤7%, preferably ≤5 wt%, the alkane content is ≤8%, preferably <5 wt%, and the aromatic content is ≤5 wt%.
[0020] Further, in step (2), the reaction conditions for the oligomerization reaction include: a temperature of 200-300℃, a pressure of 1.0-6.0 MPa, and a weight hourly space velocity of 0.5-4.0 h⁻¹. -1 ;
[0021] Preferably, in step (1), the reaction conditions of the methanol-to-olefins unit include: a temperature of 350-420℃, a pressure of 1.1-1.2 MPa, and a weight hourly space velocity of 1-1.8 h⁻¹. -1 In step (2), the reaction conditions for the oligomerization reaction include: a temperature of 200-250℃, a pressure of 4.0-6.0 MPa, and a weight hourly space velocity of 0.5-1.0 h⁻¹. -1 .
[0022] Preferably, the oligomerization reaction in step (2) is carried out in a second catalyst, which comprises a nickel-modified ZSM-5 molecular sieve and a support, wherein the support is preferably activated alumina;
[0023] The nickel-modified ZSM-5 molecular sieve is a ZSM-5 molecular sieve containing NiO, preferably the content of NiO in the nickel-modified ZSM-5 molecular sieve is 0.3-1.0 wt%; the silicon-to-aluminum ratio of the ZSM-5 molecular sieve is 30-60;
[0024] The nickel-modified ZSM-5 molecular sieve is present in the second catalyst at a content of 75-85 wt%.
[0025] Furthermore, in step (3), the initial boiling point of the aviation kerosene is 204°C and the final boiling point is 300°C.
[0026] Furthermore, the reactions in steps (1) and (2) are carried out in a fixed-bed reactor, respectively.
[0027] The technical solution provided by this invention has the following beneficial effects:
[0028] (1) The preparation process of the present invention involves directly using crude methanol to carry out methanol-to-olefin reaction under specific reaction conditions in the presence of ZSM-5 molecular sieve catalyst with a silicon-to-aluminum ratio of 80-120. After that, only simple aromatic separation is required, and oligomerization reaction is carried out directly without further separation of the remaining hydrocarbon materials. The oligomerization reaction product and the separated aromatics are mixed and hydrogenated and fractionated to directly obtain 100% aviation kerosene. This process does not involve blending with other petroleum-based oil products.
[0029] (2) The crude methanol raw material used in this invention does not require distillation, saving a lot of energy. After methanol is converted into hydrocarbons, there is no need for a complicated separation process. Only simple fractionation of aromatics is required. The remaining hydrocarbons, mainly olefins, do not need to be separated and can directly enter the oligomerization unit. The whole process does not involve a cryogenic separation process and does not involve the process of separating ethylene from butene and pentene.
[0030] (3) In the preparation process of the present invention, the methanol-to-olefins unit has good high carbon olefin selectivity and the whole process has good carbon-based total yield. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the process flow for producing aviation kerosene from methanol in one embodiment. Detailed Implementation
[0032] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.
[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" as used herein may include any and all combinations of one or more of the associated listed items. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0034] This invention provides a process for preparing methanol-based aviation kerosene, comprising the following steps:
[0035] (1) Aqueous crude methanol with a methanol concentration of 50-64wt% is reacted in the methanol-to-olefins unit in the presence of a first catalyst, and the aromatics in the resulting reaction product are separated to obtain aromatic materials and materials rich in C2-C5 olefins.
[0036] The reaction conditions for the methanol-to-olefins unit include: a temperature of 350-420℃, a pressure of 0.7-1.2 MPa, and a weight hourly space velocity of 1-4 h⁻¹. -1 ;
[0037] The active component of the first catalyst includes ZSM-5 molecular sieve, and the silicon-aluminum ratio (SiO2 / Al2O3, molar ratio) of the ZSM-5 molecular sieve is 80-120.
[0038] (2) The material rich in C2-C5 olefins is fed into the olefin oligomerization unit for oligomerization reaction to obtain oligomer products;
[0039] (3) The oligomer product in step (2) is mixed with the aromatic material to obtain a mixture. The mixture is then subjected to hydrogenation and fractionated to obtain aviation kerosene.
[0040] In the preparation process of this invention, there is no need to distill crude methanol. Crude methanol is directly used to carry out methanol-to-olefins reaction in the presence of ZSM-5 molecular sieve catalyst with a silicon-to-aluminum ratio of 80-120 under the above-mentioned specific reaction conditions. After that, only simple aromatic separation is required, and oligomerization reaction is carried out directly without further separation of the remaining hydrocarbon materials. The oligomerization reaction product and the separated aromatics are mixed and hydrogenated and fractionated to directly obtain aviation kerosene. This process does not involve blending with other petroleum-based oil products.
[0041] In step (1) of this invention, crude methanol with a methanol concentration of 50-64 wt% containing water is used directly as raw material, in conjunction with a ZSM-5 molecular sieve catalyst with a silicon-to-aluminum ratio of 80-120. Methanol-to-olefins is carried out under the specific reaction conditions described above. Combined with the specific process of this invention, methanol is ultimately converted into aviation kerosene products with high selectivity. The crude methanol raw material does not require distillation, saving a significant amount of energy. After methanol is converted into hydrocarbons, no complex separation process is needed; only simple fractionation of aromatics is required. The remaining hydrocarbons, mainly olefins, do not require separation and directly enter the oligomerization unit. The entire process does not involve cryogenic separation and does not involve the separation of ethylene from butene and pentene.
[0042] Preferably, in step (1), the crude methanol is a methanol-water solution with a methanol concentration of 50-64 wt%. This invention uses a methanol-water solution within this concentration range as a raw material to prepare aviation kerosene. Compared to using crude methanol with a lower water content, this can delay catalyst carbon deposition during the reaction process, thus extending catalyst life and improving the selectivity of C4 and C5 olefins. Compared to crude methanol with a higher water content, it helps save energy and improve reaction efficiency.
[0043] Preferably, the crude methanol is obtained during the process of producing methanol by CO2 hydrogenation.
[0044] In the first catalyst, the content of the active component is 70-80 wt%. Preferably, the first catalyst further includes a support and an auxiliary agent, wherein the auxiliary agent includes CaO, and the content of the auxiliary agent in the first catalyst is 1-10 wt%, with the balance being the support. Preferably, the support of the first catalyst is activated alumina. Adding 1-10 wt% CaO to the first catalyst is beneficial for improving the selectivity of higher carbon olefins and for increasing the total carbon-based yield.
[0045] More preferably, in the first catalyst, the content of the auxiliary agent is 3-10%, preferably 3-7%; the silicon-aluminum ratio of the ZSM-5 molecular sieve is 90-120, preferably 90-110; using the preferred first catalyst, under basically the same other conditions, is beneficial to further improve the selectivity of high carbon olefins and the total carbon-based yield.
[0046] In the preparation process of this invention, step (1) uses aqueous crude methanol with a methanol concentration of 50-64 wt%, and a ZSM-5 molecular sieve catalyst with a silicon-to-aluminum ratio of 80-120 to carry out methanol-to-olefins reaction under specific reaction conditions. Through the organic combination of the above-mentioned specific raw materials, catalysts and reaction conditions, a high C3-C5 olefin selectivity can be obtained in the methanol-to-olefins reaction. The resulting product has a low ethylene content, eliminating the need for additional ethylene separation. This product can be directly subjected to oligomerization to obtain a product rich in C8-C16 alkanes, which facilitates the subsequent hydrogenation and fractionation to directly obtain aviation kerosene products without blending, and also facilitates a high total carbon-based yield in the entire process. Through step (1) of this invention, methanol-to-olefins can be produced with a C2-C5 olefin content of 75-96 wt%, an ethylene content of ≤7%, preferably ≤5 wt%, an alkane content of ≤8%, preferably <5 wt%, and an aromatic content of ≤5 wt%.
[0047] In some embodiments, the first catalyst may be prepared by a method including the following preparation steps:
[0048] 1a) Mix ZSM-5 molecular sieve (SiO2 / Al2O3 = 80-120, molar ratio) with pseudoboehmite (Al2O3 content is, for example, about 70 wt%) and stir evenly;
[0049] 2a) Add an appropriate amount of deionized water (the amount is, for example, about 50 wt% of ZSM-5 molecular sieve, such as 40-60 wt%) and continue stirring, for example, for 30 minutes, to form a wet powder.
[0050] 3a) Add the powder to an extruder to form a strip, dry it, for example at 100-120℃ for 2-3 hours, and then calcine it, for example at 500-600℃ for 2-4 hours, to obtain ZSM-5 / Al2O3.
[0051] 4a) Dissolve the precursor of the auxiliary agent (e.g., Ca(NO3)2·4H2O) in deionized water to form a solution, and then dilute to volume with deionized water to obtain an impregnation solution;
[0052] 5a) Impregnate an equal volume of the impregnation solution onto the ZSM-5 / Al2O3 prepared in step 3a), dry it, for example at 100-120℃ for 2-3 hours, and then calcine it, for example at 500-600℃ for 2-4 hours, to obtain the first catalyst.
[0053] In a preferred embodiment, the reaction conditions for the oligomerization reaction in step (2) include: a temperature of 200-300℃, a pressure of 1.0-6.0 MPa, and a weight hourly space velocity of 0.5-4.0 h⁻¹. -1 .
[0054] In a more preferred embodiment, in step (1), the reaction conditions of the methanol-to-olefins unit include: a temperature of 350-420°C, a pressure of 1.1-1.2 MPa, and a weight hourly space velocity of 1-1.8 h⁻¹. -1 In step (2), the reaction conditions for the oligomerization reaction include: a temperature of 200-250℃, a pressure of 4.0-6.0 MPa, and a weight hourly space velocity of 0.5-1.0 h⁻¹. -1 Using optimized reaction conditions for steps (1) and (2) is beneficial for further improving the selectivity of high-carbon olefins and the total carbon-based yield.
[0055] In a preferred embodiment, the oligomerization reaction in step (2) is carried out in a second catalyst, which is a nickel-modified ZSM-5 molecular sieve catalyst. Specifically, the second catalyst comprises a nickel-modified ZSM-5 molecular sieve and a support, wherein the support is preferably activated alumina; the content of the nickel-modified ZSM-5 molecular sieve in the second catalyst is 75-85 wt%, with the remainder being the support; the nickel-modified ZSM-5 molecular sieve contains NiO, preferably with a NiO content of 0.3-1.0 wt%; and the silicon-to-aluminum ratio (SiO2 / Al2O3, molar ratio) of the ZSM-5 molecular sieve is 30-60.
[0056] In some embodiments, the second catalyst can be prepared by a method including the following preparation steps:
[0057] 1b) Preparation of nickel-modified ZSM-5 molecular sieve: ZSM-5 molecular sieve (silicon-to-aluminum ratio 30-60) is placed in a nickel salt solution (e.g., a solution with a Ni(NO3)2 concentration of 5wt%) and stirred at 60-80℃ for 0.5-1.0h to carry out ion exchange;
[0058] 2b) Filtration, drying the obtained Ni ion-exchanged ZSM-5 molecular sieve, for example, drying at 100-120℃ for 2-3 hours, and then calcining, for example, calcining at 500-600℃ for 2-4 hours, to obtain nickel-modified ZSM-5 molecular sieve containing 0.3-1.0wt% NiO;
[0059] 3b) Mix the nickel-modified ZSM-5 molecular sieve with boehmite (Al2O3 content of about 70%) and stir evenly.
[0060] 4b) Add an appropriate amount of deionized water (the amount is, for example, about 50 wt% of ZSM-5 molecular sieve, such as 40-60 wt%) and continue stirring, for example, for 30 minutes, to form a moist powder.
[0061] 5b) The powder is added to an extruder and extruded into strips, then dried, for example at 100-120°C for 2-3 hours, and then calcined, for example at 500-600°C for 2-4 hours, to obtain the shaped catalyst.
[0062] In the preparation process of the present invention, in step (2), a product rich in C8-C16 alkanes is obtained by oligomerization reaction. The C8-C16 alkanes in the product rich in C8-C16 alkanes contain 85-95 wt% C8-C16 alkanes and 5-15 wt% cycloalkanes.
[0063] Furthermore, in step (3), the initial boiling point of the aviation kerosene is 204°C and the final boiling point is 300°C.
[0064] Furthermore, the reactions in steps (1) and (2) are carried out in a fixed-bed reactor, respectively.
[0065] In this invention, the hydrogenation reaction in step (3) can be carried out using conventional hydrogenation processes in the art, where unsaturated alkanes and aromatics are hydrogenated to saturated alkanes and cycloalkanes in the hydrogenation unit. Process conditions, for example, include: a fixed-bed reactor, pressure 10-15 MPa, reaction temperature 280-320 °C, and volume hourly space velocity (VHSV) of 0.2-1.0 h⁻¹. -1 The hydrogen-to-oil ratio (the ratio of hydrogen to the liquid oil feedstock being processed) is 400-600. Unless otherwise specified in the following examples, the hydrogenation reaction is carried out under these process conditions and will not be described again.
[0066] The present invention will be further described below with reference to the embodiments, but it should not be construed as the present invention being limited thereto.
[0067] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0068] Formula for calculating the carbon-based total yield from methanol to aviation kerosene:
[0069] Y = 2.286w² / w¹ × 100%
[0070] Where w1 is the weight of methanol, w2 is the weight of aviation kerosene, and Y is the total carbon-based yield.
[0071] In Examples 1-5 below, the first catalyst used contained 5 wt% CaO, 76 wt% ZSM-5 molecular sieve, and 19 wt% activated alumina, with a silica-to-alumina ratio of 100. The preparation steps of the first catalyst are as follows:
[0072] 1) Weigh 200g of ZSM-5 molecular sieve (SiO2 / Al2O3 = 100, molar ratio) and mix it with 71.5g of pseudoboehmite (Al2O3 content is 70wt%) until homogeneous;
[0073] 2) Add 100g of deionized water and continue stirring for 30 minutes to form a moist powder;
[0074] 1) Add the powder to the extruder and extrude it into strips. Dry it at 120°C for 2 hours and then calcine it at 550°C for 3 hours to obtain ZSM-5 / Al2O3.
[0075] 4) Dissolve 54.8g Ca(NO3)2·4H2O in deionized water to form a solution, then add deionized water to make up to 100ml to obtain the impregnation solution;
[0076] 5) Impregnate an equal volume of the impregnation solution onto the ZSM-5 / Al2O3 prepared in step 3), dry at 120°C for 2 hours, and then calcine at 550°C for 3 hours to obtain the catalyst; the catalyst composition is CaO 5wt%, ZSM-5 76wt%, and Al2O3 19wt%.
[0077] In Examples 1-5 below, the second catalyst used contained: 80 wt% nickel-modified ZSM-5 molecular sieve (of which the content of NiO was 0.48 wt% and the content of ZSM-5 molecular sieve was 79.52 wt%, based on the mass of the second catalyst), 20 wt% active alumina, and a silica-to-alumina ratio of 30 for the ZSM-5 molecular sieve. The preparation steps of the second catalyst are as follows:
[0078] 1) Take 200g of ZSM-5 molecular sieve (SiO2 / Al2O3 = 30, molar ratio) and put it into 2000g of Ni(NO3)2 aqueous solution with a concentration of 5wt%, and stir at 80℃ for 1.0h to carry out ion exchange;
[0079] 2) Filtration: The obtained Ni ion-exchanged ZSM-5 molecular sieve was dried at 120℃ for 2h and then calcined at 550℃ for 3h to obtain nickel-modified ZSM-5 molecular sieve, wherein the contents of NiO and ZSM-5 were 0.6wt% and 99.4wt%, respectively.
[0080] 3) Weigh 200g of nickel-modified ZSM-5 molecular sieve and mix it with 71.5g of pseudoboehmite (Al2O3 content is 70wt%) until homogeneous;
[0081] 4) Add 100g of deionized water and continue stirring for 30 minutes to form a moist powder;
[0082] 5) Add the powder to the extruder and extrude it into strips. Dry it at 120°C for 2 hours and then calcine it at 550°C for 3 hours to obtain the shaped catalyst.
[0083] Example 1:
[0084] (1) A 50% (w / w) methanol-to-olefins (MTO) aqueous solution was fed into the methanol-to-olefins unit. A fixed-bed reactor was used, and the reaction was carried out in the presence of a first catalyst at a temperature of 350°C, a pressure of 1.0 MPa, and a weight hourly space velocity (WHSV) of 2 h⁻¹. -1 The product contains 1 wt% ethylene, 15 wt% propylene, 32 wt% butene, 45 wt% pentene, 5 wt% aromatics, and 2 wt% methane and other alkanes. The product is fractionated to separate the aromatics, and the remaining material rich in C2-C5 olefins enters the olefin oligomerization unit.
[0085] (2) The olefin oligomerization unit adopts a fixed-bed reactor and the reaction is carried out in the presence of a second catalyst at a reaction temperature of 200℃, a pressure of 1.0MPa, and a weight hourly space velocity of 0.5h. -1 ; to obtain aggregated products.
[0086] (3) The oligomer product is mixed with the aromatics separated in step (1) and fed into a hydrogenation unit to hydrogenate the unsaturated alkanes and aromatics into saturated alkanes and cycloalkanes. After fractionation, the fraction with an initial boiling point of 204°C and a final boiling point of 300°C is taken. The product meets the GB6537-2018 aviation kerosene standard.
[0087] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 79%.
[0088] Example 2
[0089] (1) A 64% (w / w) methanol-to-olefins (MTO) aqueous solution was fed into the methanol-to-olefins unit. A fixed-bed reactor was used, and the reaction was carried out in the presence of a first catalyst at a temperature of 420°C, a pressure of 0.7 MPa, and a weight hourly space velocity (WHSV) of 4 h⁻¹. -1The product contains 5 wt% ethylene, 38 wt% propylene, 27 wt% butene, 23 wt% pentene, 3 wt% aromatics, and 4 wt% methane and other alkanes. The product is fractionated to separate the aromatics, and the remaining material rich in C2-C5 olefins enters the olefin oligomerization unit.
[0090] (2) The olefin oligomerization unit adopts a fixed-bed reactor and the reaction is carried out in the presence of a second catalyst at a reaction temperature of 200℃, a pressure of 6.0MPa, and a weight hourly space velocity of 0.5h. -1 ; Obtain aggregated products;
[0091] (3) The oligomer product is mixed with the aromatics separated in step (1) and fed into a hydrogenation unit to hydrogenate the unsaturated alkanes and aromatics into saturated alkanes and cycloalkanes. After fractionation, the fraction with an initial boiling point of 204°C and a final boiling point of 300°C is taken. The product meets the GB6537-2018 aviation kerosene standard.
[0092] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 78%.
[0093] Example 3
[0094] (1) A 58% (w / w) methanol-to-olefins (MTO) aqueous solution was fed into the methanol-to-olefins unit. A fixed-bed reactor was used, and the reaction was carried out in the presence of a first catalyst at a temperature of 385°C, a pressure of 0.9 MPa, and a weight hourly space velocity (WHSV) of 2.5 h⁻¹. -1 The product contains 3 wt% ethylene, 27 wt% propylene, 35 wt% butene, 28 wt% pentene, 4 wt% aromatics, and 3 wt% methane and other alkanes. The product is fractionated to separate the aromatics, and the remaining material rich in C2-C5 olefins enters the olefin oligomerization unit.
[0095] (2) The olefin oligomerization unit adopts a fixed-bed reactor and the reaction is carried out in the presence of a second catalyst at a reaction temperature of 250℃, a pressure of 3.0MPa, and a weight hourly space velocity of 2.5h. -1 ; Obtain aggregated products;
[0096] (3) The oligomer product is mixed with the aromatics separated in step (1) and fed into a hydrogenation unit to hydrogenate the unsaturated alkanes and aromatics into saturated alkanes and cycloalkanes. After fractionation, the fraction with an initial boiling point of 204°C and a final boiling point of 300°C is taken. The product meets the GB6537-2018 aviation kerosene standard.
[0097] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 78%.
[0098] Example 4
[0099] (1) A 64% (w / w) methanol-to-olefins (MTO) aqueous solution was fed into the methanol-to-olefins unit. A fixed-bed reactor was used, and the reaction was carried out in the presence of a first catalyst at a temperature of 420°C, a pressure of 0.7 MPa, and a weight hourly space velocity (WHSV) of 4 h⁻¹. -1 The product contains 5 wt% ethylene, 38 wt% propylene, 27 wt% butene, 23 wt% pentene, 3 wt% aromatics, and 4 wt% methane and other alkanes. The product is fractionated to separate the aromatics, and the remaining material rich in C2-C5 olefins enters the olefin oligomerization unit.
[0100] (2) The olefin oligomerization unit adopts a fixed-bed reactor, and the reaction is carried out in the presence of a second catalyst at a reaction temperature of 300℃, a pressure of 1.0MPa, and a weight hourly space velocity of 4.0h. -1 ; Obtain aggregated products;
[0101] (3) The oligomer product is mixed with the aromatics separated in step (1) and fed into a hydrogenation unit to hydrogenate the unsaturated alkanes and aromatics into saturated alkanes and cycloalkanes. After fractionation, the fraction with an initial boiling point of 204°C and a final boiling point of 300°C is taken. The product meets the GB6537-2018 aviation kerosene standard.
[0102] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 75%.
[0103] Example 5
[0104] (1) A 50% (w / w) methanol-to-olefins (MTO) aqueous solution was fed into the methanol-to-olefins (MTO) unit. A fixed-bed reactor was used, and the reaction was carried out in the presence of a first catalyst at a temperature of 350°C, a pressure of 1.2 MPa, and a weight hourly space velocity (WHSV) of 1 h⁻¹. -1 The product contains 0.5 wt% ethylene, 8 wt% propylene, 37.5 wt% butene, 47 wt% pentene, 5 wt% aromatics, and 2 wt% methane and other alkanes. The product is fractionated to separate the aromatics, and the remaining material rich in C2-C5 olefins enters the olefin oligomerization unit.
[0105] (2) The olefin oligomerization unit adopts a fixed-bed reactor and the reaction is carried out in the presence of a second catalyst at a reaction temperature of 200℃, a pressure of 6.0MPa, and a weight hourly space velocity of 0.5h. -1 ; to obtain aggregated products.
[0106] (3) The oligomer product is mixed with the aromatics separated in step (1) and fed into a hydrogenation unit to hydrogenate the unsaturated alkanes and aromatics into saturated alkanes and cycloalkanes. After fractionation, the fraction with an initial boiling point of 204°C and a final boiling point of 300°C is taken. The product meets the GB6537-2018 aviation kerosene standard.
[0107] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 80%.
[0108] Table 1. Summary of reaction conditions and results for Examples 1-5
[0109]
[0110] Note: If the data in Table 1 is inconsistent with the descriptions in Examples 1-5, the textual descriptions in Examples 1-5 shall prevail.
[0111] Example 6
[0112] The process was carried out in accordance with Example 1, except that the contents of CaO, ZSM-5 molecular sieve and Al2O3 in the first catalyst were 1wt%, 70wt% and 29wt% respectively, the silicon-aluminum ratio of ZSM-5 molecular sieve was 80, and the preparation steps of the catalyst were carried out in accordance with the preparation process of the first catalyst used in Example 1.
[0113] The other reaction conditions in this embodiment are the same as in Example 1.
[0114] Results: The methanol-to-olefins unit product contained 5 wt% ethylene, 20 wt% propylene, 32 wt% butene, 33 wt% pentene, 5 wt% aromatics, and 5 wt% methane and other alkanes. The final product met the GB6537-2018 aviation kerosene standard.
[0115] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 75%.
[0116] Example 7
[0117] The process was carried out in accordance with Example 1, except that the contents of CaO, ZSM-5 molecular sieve and Al2O3 in the first catalyst were 10wt%, 70wt% and 20wt% respectively, the silicon-aluminum ratio of ZSM-5 molecular sieve was 120, and the preparation steps of the catalyst were the same as those of the first catalyst used in Example 1.
[0118] The other reaction conditions in this embodiment are the same as in Example 1.
[0119] Results: The methanol-to-olefins unit product contained 5 wt% ethylene, 36 wt% propylene, 30 wt% butene, 25 wt% pentene, 3 wt% aromatics, and 1 wt% methane and other alkanes. The final product met the GB6537-2018 aviation kerosene standard.
[0120] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 77%.
[0121] Example 8 (Compared to Example 1, the first catalyst does not contain CaO)
[0122] The experiment was conducted in accordance with Example 1, except that the first catalyst used did not contain CaO, and the contents of ZSM-5 molecular sieve and Al2O3 were 80wt% and 20wt% respectively, and the silicon-aluminum ratio of ZSM-5 molecular sieve was 100.
[0123] The other reaction conditions in this embodiment are the same as in Example 1.
[0124] Results: The methanol-to-olefins unit product contained 7 wt% ethylene, 24 wt% propylene, 28 wt% butene, 30 wt% pentene, 3 wt% aromatics, and 8 wt% methane and other alkanes. The final product met the GB6537-2018 aviation kerosene standard.
[0125] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 72%.
[0126] Comparative Example 1
[0127] The process was carried out in accordance with Example 4, except that the silicon-aluminum ratio of the ZSM-5 molecular sieve in the first catalyst was 70, and the catalyst was prepared in accordance with the preparation process of the first catalyst used in Example 1.
[0128] The other reaction conditions for this comparative example are the same as those for Example 4.
[0129] Results: The methanol-to-olefins unit products contained 3 wt% ethylene, 30 wt% propylene, 29 wt% butene, 25 wt% pentene, 8 wt% aromatics, and 5 wt% methane and other alkanes.
[0130] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 71%.
[0131] Comparative Example 2
[0132] The process was carried out in accordance with Example 4, except that the silicon-aluminum ratio of the ZSM-5 molecular sieve in the first catalyst was 140, and the catalyst was prepared in accordance with the preparation process of the first catalyst used in Example 1.
[0133] The other reaction conditions for this comparative example are the same as those for Example 4.
[0134] Results: The methanol-to-olefins unit product contained 12 wt% ethylene, 45 wt% propylene, 25 wt% butene, 15 wt% pentene, 1.5 wt% aromatics, and 1.5 wt% methane and other alkanes.
[0135] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 70%.
[0136] Comparative Example 3
[0137] The reaction was carried out in accordance with Example 4, except that the reaction conditions for the methanol-to-olefins unit were: a reaction temperature of 550°C, a pressure of 0.5 MPa, and a weight hourly space velocity of 1 h⁻¹. -1 .
[0138] Results: The methanol-to-olefins unit products contained 18 wt% ethylene, 42% propylene, 27 wt% butene, 10 wt% pentene, 1 wt% aromatics, and 2 wt% methane and other alkanes.
[0139] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 68%.
[0140] Comparative Example 4
[0141] The reaction was carried out in accordance with Example 4, except that the reaction conditions for the methanol-to-olefins unit were: a reaction temperature of 350°C, a pressure of 2.0 MPa, and a weight hourly space velocity of 1 h⁻¹. -1 .
[0142] Results: The methanol-to-olefins unit products contained 3 wt% ethylene, 30% propylene, 22 wt% butene, 15 wt% pentene, 20 wt% aromatics, and 10 wt% methane and other alkanes.
[0143] Calculations show that the total carbon-based yield from methanol to aviation kerosene is 65%.
[0144] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom remain within the scope of protection of this invention.
Claims
1. A process for preparing methanol-to-aviation kerosene, characterized in that, Includes the following steps: (1) Aqueous crude methanol with a methanol concentration of 50-64wt% is reacted in the methanol-to-olefins unit in the presence of a first catalyst, and the aromatics in the resulting reaction product are separated to obtain aromatic materials and materials rich in C2-C5 olefins. The reaction conditions for the methanol-to-olefins unit include: a temperature of 350-420℃, a pressure of 0.7-1.2 MPa, and a weight hourly space velocity of 1-4 h⁻¹. -1 ; The active component of the first catalyst includes ZSM-5 molecular sieve, and the silica-alumina ratio of the ZSM-5 molecular sieve is 80-120. (2) The material rich in C2-C5 olefins is fed into the olefin oligomerization unit for oligomerization reaction to obtain oligomer products; (3) The oligomer product described in step (2) is mixed with the aromatic material to obtain a mixture. The mixture is then subjected to hydrogenation and fractionated to obtain aviation kerosene.
2. The preparation process according to claim 1, characterized in that, In step (1), the crude methanol is an aqueous methanol solution; Preferably, the crude methanol is obtained during the process of producing methanol by CO2 hydrogenation.
3. The preparation process according to claim 1 or 2, characterized in that, In the first catalyst, the content of the active component is 70-80 wt%.
4. The preparation process according to claim 3, characterized in that, The first catalyst includes a support, and preferably also includes an auxiliary agent, wherein the auxiliary agent includes CaO, and the content of the auxiliary agent in the first catalyst is 1-10 wt%. Preferably, the support for the first catalyst is activated alumina.
5. The preparation process according to claim 4, characterized in that, In the first catalyst, the content of the auxiliary agent is 3-10%, preferably 3-7%; the silicon-aluminum ratio of the ZSM-5 molecular sieve is 90-120, preferably 90-110.
6. The preparation process according to any one of claims 1-5, characterized in that, In the reaction product of step (1), the C2-C5 olefin content is 75-96 wt%, the ethylene content is ≤7%, preferably ≤5 wt%, the alkane content is ≤8%, preferably <5 wt%, and the aromatic content is ≤5 wt%.
7. The preparation process according to any one of claims 1-6, characterized in that, In step (2), the reaction conditions for the oligomerization reaction include: a temperature of 200-300℃, a pressure of 1.0-6.0 MPa, and a weight hourly space velocity of 0.5-4.0 h⁻¹. -1 ; Preferably, in step (1), the reaction conditions of the methanol-to-olefins unit include: a temperature of 350-420℃, a pressure of 1.1-1.2 MPa, and a weight hourly space velocity of 1-1.8 h⁻¹. -1 In step (2), the reaction conditions for the oligomerization reaction include: a temperature of 200-250℃, a pressure of 4.0-6.0 MPa, and a weight hourly space velocity of 0.5-1.0 h⁻¹. -1 .
8. The preparation process according to claim 7, characterized in that, The oligomerization reaction in step (2) is carried out in a second catalyst, which comprises a nickel-modified ZSM-5 molecular sieve and a support, preferably active alumina. The nickel-modified ZSM-5 molecular sieve is a ZSM-5 molecular sieve containing NiO, preferably the content of NiO in the nickel-modified ZSM-5 molecular sieve is 0.3-1.0 wt%; the silicon-to-aluminum ratio of the ZSM-5 molecular sieve is 30-60; The content of the nickel-modified ZSM-5 molecular sieve in the second catalyst is 75-85 wt%.
9. The preparation process according to any one of claims 1-8, characterized in that, In step (3), the initial boiling point of the aviation kerosene is 204°C and the final boiling point is 300°C.
10. The preparation process according to any one of claims 1-9, characterized in that, The reactions in steps (1) and (2) are carried out in a fixed-bed reactor.