Method for producing aviation kerosene from medium distillate oil

Abstract

The invention discloses a method for producing aviation kerosene from medium distillate oil, which comprises the following steps: (1) carrying out catalytic reforming on the medium distillate oil in a first reactor in the presence of a modified hydroxyapatite catalyst, and then separating the obtained reforming product to obtain C8-C16 fractions; and (2) feeding the C8-C16 fractions separated in the step (1) into a second reactor, carrying out isomerization pour point depressing treatment in the presence of an isomerization pour point depressing catalyst, and then separating light components below C8 in an obtained isomerization product to obtain the aviation kerosene. The matched raw materials are wide in source, particularly, the wide-fraction medium distillate oil can be used as the raw material, the non-ideal carbon number raw material of the medium distillate oil raw material is directionally cracked and converted into the ideal carbon number raw material for processing the aviation fuel in the first reactor, the raw material is separated and then enters the second reaction unit for isomerization reaction, the yield of the obtained aviation fuel fraction section is high, and the production cost is low. And the yield can reach 70% or above.

Description

Technical Field

[0001] The present invention relates to the field of deep processing of oil products, and in particular to a method for producing aviation kerosene from middle distillate oil. Background Art

[0002] Middle distillates generally refer to distillates with a boiling point between 200-400°C (typically with carbon numbers between C12-C24). They can be derived from petroleum, Fischer-Tropsch oils, or biomass oils. These fractions are often used as diesel or crude chemical feedstock and have relatively low added value. In recent years, with the growth of the aviation industry, the demand for jet fuel, particularly bio-jet fuel, has increased, creating a market advantage for converting middle distillates into jet fuel fractions.

[0003] CN109701625A discloses a method for producing an isomerized pour point depressing catalyst and bio-jet kerosene. The isomerized pour point depressing catalyst contains two twelve-membered ring silica-alumina molecular sieves, at least one of which contains mesopores. The catalyst is used to directly isomerize and depress the pour point of crude oil to obtain bio-jet kerosene. However, the preparation of the catalyst is complex and the yield of bio-jet kerosene is difficult to achieve a higher expected value.

[0004] CN107573967A discloses a hydrocracking method for producing jet fuel, in which diesel fraction feedstock is sequentially hydrotreated over two hydrocracking catalysts, I and II, wherein catalyst I contains a Beta molecular sieve and catalyst II contains a medium-pore molecular sieve, ZSM-5. When the feedstock contacts catalyst I, in addition to a refining reaction, a branching reaction of paraffins and alkyl side chains also occurs. The reaction product then contacts catalyst II to further convert a small amount of high-carbon normal alkanes to reduce the content of high-carbon normal alkanes, thereby lowering the freezing point of the product.

[0005] The document "Hydroisomerization Reaction of Fischer-Tropsch Synthesis Distillate Oil over Pt / ZSM-12 Catalyst" (Xu Xiaoling et al., Natural Gas Chemical Industry, 2019(2)) discloses that LTFT (low temperature Fischer-Tropsch) synthesis distillate oil with a distillation range of 192-397°C is used as raw material, and Pt / ZSM-12 is used as catalyst to carry out isomerization and pour point reduction at a higher reaction temperature. The light diesel fraction in the product can be used to produce alternative jet fuel, but the maximum yield is only 22.75%.

[0006] As can be seen from the above, existing approaches for producing jet fuel from middle distillates primarily rely on hydrocracking, which uses a cracking catalyst to crack the middle distillate and separate the C8-C16 fraction via distillation to produce jet fuel. Alternatively, a direct isomerization pour point decompression method is employed, utilizing the non-selective cracking that occurs simultaneously with the pour point decompression process to produce jet fuel fractions. These technical approaches suffer from low jet fuel fraction yields if the feedstock has a wide distillation range, and this problem is exacerbated if the feedstock has a heavy distillation range. Summary of the Invention

[0007] The object of the present invention is to provide a method for producing aviation kerosene from middle distillate oil, thereby using middle distillate oil with a wide distillation range as raw material and producing aviation kerosene that meets the requirements with high yield.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for producing aviation kerosene from middle distillate oil comprises the following steps:

[0010] (1) catalytically reforming the middle distillate oil in the presence of a modified hydroxyapatite catalyst in a first reactor, and then separating the resulting reformed product to obtain a C8-C16 fraction;

[0011] (2) The C8-C16 fraction separated in step (1) is fed into a second reactor and subjected to isomerization depressing treatment in the presence of an isomerization depressing catalyst, and then the light components below C8 in the obtained isomerized product are separated, and the remaining components are aviation kerosene.

[0012] In step (1) of the present invention, the catalyst used in the first reactor is modified hydroxyapatite, and the middle distillate oil feedstock is catalytically reformed to be mostly directionally reformed into a C8-C16 fraction, thereby directionally cracking the non-ideal carbon number feedstock into an ideal carbon number feedstock for processing aviation kerosene, and after separating the light components below C8 and the components above C16, a C8-C16 component is obtained; the specific separation is well known in the art, for example, the separation described in step (1) can be atmospheric distillation, thin film evaporation or supercritical extraction, which will not be repeated here.

[0013] The catalyst loaded in the first reactor is modified hydroxyapatite so as to reform the crude oil. In order to improve the reforming conversion capacity of the catalyst for middle distillate oil, preferably, the modified hydroxyapatite is prepared by using commercially available hydroxyapatite by the following method: 100 parts by weight of hydroxyapatite is uniformly mixed with 1-10 parts by weight, such as 2, 5 or 8 parts by weight of nickel salt, 5-20 parts by weight, such as 8, 10 or 15 parts by weight of alkaline peptizing agent and 5-20 parts by weight, such as 8, 10 or 15 parts by weight of water for more than 0.5 hours, such as 0.5-2 hours or 1 hour, and then the resulting mixture is extruded, dried, and calcined to form a modified hydroxyapatite catalyst; wherein the nickel salt includes one or more of nickel nitrate, basic nickel carbonate and nickel hydroxide, and the alkaline peptizing agent includes one or more of industrial ammonia water, triethylamine and ethylenediamine.

[0014] In the preparation process of the modified hydroxyapatite of the present invention, the extrusion, drying and calcination are conventional operations in the art and are well known in the art. For example, the uniformly mixed mixture is extruded into long strips with a diameter of 1-3 mm, and then dried at 80-100°C, and finally calcined to form, for example, calcined at 450-550°C for 3-8 hours.

[0015] In a preferred embodiment, when the catalytic reforming reaction is carried out, the suitable reaction conditions in the first reactor are as follows: the reaction temperature is 250-400°C, such as 280, 320, 350 or 380°C, preferably 300-360°C, and the mass space velocity is 0.5-3.0h -1 For example, 0.8, 1.2, 2 or 2.5 hours -1 , preferably 1.0-1.5h -1 The reaction atmosphere is an inert atmosphere, such as nitrogen, argon or helium, preferably nitrogen, and the reaction pressure is from normal pressure to 6.0 MPa, such as 1, 3 or 5 MPa, preferably from normal pressure to 3.5 MPa.

[0016] In step (2) of the present invention, the C8-C16 components separated after reforming in step (1) are subjected to isomerization decondensation refining in the second reactor, and the product is separated into light components below C8 (i.e., C7 and C7 components below. Of course, it is understood in the art that a very small amount of C8 components will inevitably be mixed in during the separation process), and the remaining component is aviation kerosene; the specific separation is well known in the art, for example, separation is carried out by controlling the separation pressure and temperature, such as in step (2) by atmospheric distillation, thin film evaporation or supercritical extraction, which will not be repeated here.

[0017] The isomerized pour point-depressing catalyst loaded in the second reactor can be an isomerized pour point-depressing catalyst commonly used in the art. In one embodiment, the isomerized pour point-depressing catalyst can be a commercially available Pt-type isomerized pour point-depressing catalyst, that is, a Pt-type isomerized catalyst supported by a molecular sieve. The molecular sieve can be SAPO-11, ZSM-22, ZSM-23 or ZSM-48, preferably ZSM-48, to lower the freezing point of the product and have a refining function. For example, the Pt-type isomerized pour point-depressing catalyst can be a commercially available PHI or RIW-type isomerized pour point-depressing catalyst. The preparation method thereof is known in the art, for example, refer to CN 109701625A. The specific preparation process may include: mixing the molecular sieve with a binder, forming, then loading the active metal component, for example, by impregnation, and then calcining and reduction activation, wherein the binder can be alumina. In some embodiments, the heterogeneous pour point catalyst includes a molecular sieve, a binder, and a supported active metal Pt, wherein the mass ratio of the molecular sieve, the binder, and the active metal is (60-70):(25-40):(0.2-0.5), for example, molecular sieve:alumina:Pt=65:35:0.35.

[0018] In a preferred embodiment, when performing the isomerization pour point reaction, the suitable reaction conditions in the second reactor are as follows: the reaction temperature is 250-380°C, such as 280, 300 or 360°C, preferably 260-330°C, and the mass space velocity is 0.5-3.0h -1 For example, 0.8, 1.2, 1.8 or 2.5 hours -1 , preferably 1.0-2.0h -1 The hydrogen-to-oil volume ratio is 200-1000, such as 300, 500 or 800, preferably 400-600, and the reaction pressure is 1.0-8.0 MPa, such as 2, 4 or 5 MPa, preferably 3.0-6.0 MPa.

[0019] In the present invention, the medium distillate oil used as a raw material generally refers to a fraction with a carbon number in the range of C12-C24 and a boiling point in the range of 200-400°C, and can be derived from petroleum, Fischer-Tropsch oil or bio-oil.

[0020] In the present invention, the concentrations or percentages involved are all mass concentrations or mass percentages unless otherwise specified.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The present invention opens up a new technical route for preparing aviation kerosene, which has a wide range of matching raw materials, especially wide-fraction middle distillate oil. The middle distillate oil raw material is firstly subjected to directional cracking in a first reactor using modified hydroxyapatite as a directional reforming catalyst to convert the non-ideal carbon number raw material into an ideal carbon number raw material for processing aviation kerosene. After separation, the raw material enters a second reaction unit for an isomerization reaction to lower the freezing point and remove unstable components. The product is fractionated to obtain aviation kerosene fraction, and the aviation kerosene fraction yield reaches more than 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a process for preparing aviation kerosene in the present invention;

[0024] Among them, 1 is the first reactor; 2 is the first separation unit; 3 is the second reactor; and 4 is the second separation unit. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the embodiments. However, the present invention is not limited to the listed embodiments, but also includes equivalent improvements and modifications of the technical solutions defined in the claims attached to the patent application of the present invention.

[0026] The endpoints of the ranges and any values ​​disclosed herein are not limited to the exact ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values, such as values ​​±10% of the endpoints. For numerical ranges, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0027] like Figure 1 As shown, when the present invention uses middle distillate oil as a raw material to prepare aviation kerosene, the first reactor is loaded with modified hydroxyapatite as a catalyst. The middle distillate oil raw material is processed by the first reactor, and most of the C8-C16 fraction is directionally reformed. After the light components below C8 and the heavy components above C16 are separated by the first separation unit, a C8-C16 component is obtained. The separated C8-C16 component is then fed into the second reactor (loaded with an isomerization pour point depressing catalyst) for isomerization pour point depressing refining. The light components below C8 are separated by the second separation unit, and the remaining component is aviation kerosene.

[0028] The present invention is further described below with reference to the following examples / comparative examples. Unless otherwise specified, all relevant reagents in the following examples / comparative examples are of analytical grade.

[0029] Example 1

[0030] Preparation of modified hydroxyapatite catalyst: 100 g of hydroxyapatite (source: Jinan Huijinchuan Chemical Co., Ltd., the same below) was kneaded with 6.8 g of basic nickel carbonate, 9.2 g of industrial ammonia water, and 13.1 g of water for 40 minutes. After extrusion, the mixture was dried at 90°C for 5 hours and calcined at 480°C for 3 hours to obtain catalyst 1#.

[0031] Example 2

[0032] Preparation of modified hydroxyapatite catalyst: 100 g of hydroxyapatite was kneaded with 9.6 g of nickel nitrate, 10.3 g of triethylamine, and 10.7 g of water for 40 minutes. After extrusion, the mixture was dried at 90°C for 5 hours and calcined at 550°C for 7 hours to obtain catalyst 2#.

[0033] Example 3

[0034] Preparation of modified hydroxyapatite catalyst: 100 g of hydroxyapatite was kneaded with 1.8 g of nickel hydroxide, 13.0 g of ethylenediamine, and 8.5 g of water for 40 minutes. After extrusion, the mixture was dried at 90°C for 5 hours and calcined at 450°C for 3 hours to obtain catalyst 3#.

[0035] Example 4

[0036] Use Figure 1In the process shown, the first reactor is loaded with catalyst 1#, and the medium distillate oil feedstock is treated in the first reactor to separate the C8-C16 components. The components enter the second reactor (the isomerization pour point depressing catalyst is RIW-2 type catalyst from Sinopec, the same below) for isomerization pour point depressing refining. The product is separated into light components below C8 by the second separation unit, and the remaining components are aviation kerosene.

[0037] The middle distillate oil is second-generation biodiesel with a distillation range of 239-371°C. Specific indicators are shown in Table 1.

[0038] The reaction conditions in the first reactor are as follows: reaction temperature is 340 ° C, mass space velocity is 1.2h -1 , the reaction atmosphere is nitrogen, and the reaction pressure is 2.0 MPa;

[0039] The reaction conditions in the second reactor are as follows: reaction temperature is 305°C, mass space velocity is 1.0h -1 , the hydrogen-to-oil volume ratio is 600, and the pressure is 6.0MPa.

[0040] Please see Table 4 for product test results.

[0041] Table 1:

[0042]

[0043]

[0044] Example 5

[0045] Compared with Example 4, the difference is that the middle distillate oil used is the refined distillate oil in the Fischer-Tropsch synthesis oil, and the specific indicators are shown in Table 2; the first reactor is filled with catalyst 2#, and the reaction conditions therein are as follows: the reaction temperature is 320°C, the mass space velocity is 1.5h -1 The reaction atmosphere was nitrogen and the reaction pressure was 3.5 MPa. The reaction conditions in the second reactor were as follows: reaction temperature was 280°C, mass space velocity was 1.0 h -1 , the hydrogen-to-oil volume ratio is 400, and the pressure is 3.0 MPa. Other conditions are the same as in Example 4. See Table 4 for the product test results.

[0046] Table 2:

[0047]

[0048] Example 6

[0049] Compared with Example 4, the difference is that the middle distillate oil used is straight-run diesel oil, and the specific indicators are shown in Table 3; the first reactor is filled with catalyst 3#, and the reaction conditions are as follows: the reaction temperature is 360°C, the mass space velocity is 1.0h -1, the reaction atmosphere is nitrogen, the reaction pressure is P normal pressure; the reaction conditions in the second reactor are as follows: reaction temperature is 330 ° C, mass space velocity is 2.0h -1 The volume ratio of hydrogen to oil was 600, and the pressure was 3.0 MPa. The rest was the same as in Example 4. See Table 4 for the product test results.

[0050] Table 3:

[0051]

[0052] Comparative Example 1

[0053] Compared to Example 4, the feedstock was not passed through the first reactor and the first separation unit, but directly entered the second reactor for isomerization and pour point decompression. The product was separated into light components below C8 and heavy components above C16 by the separation unit, with the remaining component being aviation kerosene. The product test results are shown in Table 4.

[0054] Comparative Example 2

[0055] Compared to Example 5, the feedstock was not passed through the first reactor and the first separation unit, but directly entered the second reactor for isomerization and pour point decompression. The product was separated into light components below C8 and heavy components above C16 by the separation unit, with the remaining component being aviation kerosene. The product test results are shown in Table 4.

[0056] Comparative Example 3

[0057] Compared to Example 6, the feedstock was not passed through the first reactor and the first separation unit, but directly entered the second reactor for isomerization and pour point decompression. The product was separated into light components below C8 and heavy components above C16 by the separation unit, with the remaining component being aviation kerosene. The product test results are shown in Table 4.

[0058] Table 4

[0059] Jet fuel yield / wt% Jet fuel freezing point / ℃ Example 4 74.1 -55 Example 5 71.5 -53 Example 6 65.2 -51 Comparative Example 1 52.3 -51 Comparative Example 2 35.8 -54 Comparative Example 3 43.2 -51

[0060] The jet fuel yield is the mass ratio of the jet fuel obtained to the middle distillate oil used as the raw material.

[0061] It can be seen from the above embodiments and comparative examples that by adopting the technical route of the present invention, a significantly higher aviation kerosene yield can be obtained when the freezing point index is similar.

Claims

1. A method for producing aviation kerosene from middle distillate oil, comprising the following steps: (1) catalytically reforming the middle distillate oil in the presence of a modified hydroxyapatite catalyst in a first reactor and separating the product to obtain a C8-C16 fraction; (2) The C8-C16 fraction separated in step (1) is fed into a second reactor and subjected to isomerization degreasing treatment in the presence of an isomerization refining catalyst, and the light components below C8 in the product are separated, and the remaining components are aviation kerosene.

2. The method according to claim 1, characterized in that The preparation method of the modified hydroxyapatite catalyst is as follows: 100 parts by weight of hydroxyapatite is uniformly mixed with 1-10 parts by weight of nickel salt, 5-20 parts by weight of alkaline peptizing agent and 5-20 parts by weight of water for more than 0.5, and then extruded, dried and calcined to obtain; The nickel salt is one or more of nickel nitrate, basic nickel carbonate and nickel hydroxide, and the alkaline peptizing agent is one or more of industrial ammonia water, triethylamine and ethylenediamine.

3. The method according to claim 2, characterized in that The calcination temperature is 450-550° C., and the calcination time is 3-8 hours.

4. The method according to any one of claims 1 to 3, characterized in that When catalytic reforming is carried out in step (1), the reaction temperature in the first reactor is 250-400°C, and the mass space velocity is 0.5-3.0h -1 , the reaction atmosphere is an inert atmosphere, and the reaction pressure is from normal pressure to 6.0 MPa.

5. The method according to claim 4, characterized in that When catalytic reforming is performed in step (1), the reaction temperature in the first reactor is 300-360°C, and the mass space velocity is 1.0-1.5h -1 The reaction atmosphere is nitrogen, argon or helium, and the reaction pressure is from normal pressure to 3.5 MPa.

6. The method according to claim 1 or 5, characterized in that The isomerization catalyst is a Pt-type isomerization catalyst supported by a molecular sieve, and the molecular sieve is SAPO-11, ZSM-22, ZSM-23 or ZSM-48, preferably ZSM-48.

7. The method according to claim 6, characterized in that The isomerized pour point depressant catalyst comprises a molecular sieve, a binder and a supported active metal Pt, wherein the mass ratio of the molecular sieve, the binder and the active metal Pt is (60-70):(25-40):(0.2-0.5).

8. The method according to claim 6 or 7, characterized in that The reaction temperature in the second reactor is 250-380°C, and the mass space velocity is 0.5-3.0h -1 , the hydrogen-oil volume ratio is 200-1000, and the reaction pressure is 1.0-8.0MPa.

9. The method according to claim 8, characterized in that The reaction temperature in the second reactor is 260-330°C, and the mass space velocity is 1.0-2.0h -1 , the hydrogen-oil volume ratio is 400-600, and the reaction pressure is 3.0-6.0MPa.

10. The method according to any one of claims 1 to 9, characterized in that The middle distillate oil is a distillate oil with a boiling point in the range of 200-400° C., which is derived from petroleum, Fischer-Tropsch synthetic oil or biomass oil.

Images