Catalyst for preparing aviation kerosene through carbon dioxide hydrogenation, and preparation method and application thereof

Abstract

The invention provides a Fe-Cu catalyst, the Fe-Cu catalyst comprises an iron-containing compound, copper, an electronic auxiliary agent and a structure auxiliary agent, the iron-containing compound is a mixture of Fe3O4, Fe7C3 and Fe5C2, and the mass ratio of Fe3O4 to Fe7C3 to Fe5C2 is 1: (0.5-2): (0.5-2). The Fe-Cu catalyst disclosed by the invention has relatively high activity, can greatly improve the selectivity of a C8 + aviation kerosene product, provides a new idea for preparing high-added-value chemicals through carbon dioxide hydrogenation, and has a relatively good industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide conversion, in particular to a catalyst for preparing aviation kerosene by carbon dioxide hydrogenation, a preparation method and application thereof. BACKGROUND

[0002] Aviation kerosene is used as the fuel of aviation turbine engine, which has the advantages of suitable density, high calorific value, good combustion performance, less carbon deposition, good low-temperature fluidity, good thermal stability and oxidation stability, high cleanliness and less corrosion to machine parts, and is widely used in civil and military aircraft. Unlike other vehicles, aviation kerosene cannot be replaced by new energy power due to the special requirements of aviation engine on energy density and weight of fuel. Aviation kerosene is mainly composed of hydrocarbon compounds with carbon number C8-C16, and the current source is mainly petroleum refining products, and can also be obtained by coal liquefaction process, natural gas liquefaction and biomass liquefaction. Coal, oil and natural gas are non-renewable fossil fuels, and with the gradual depletion of resources, the source of aviation kerosene will also be sharply reduced. Although biomass liquefaction is a renewable energy, the main cost is the large-scale collection of oil-containing biomass, and it is difficult to form large-scale production at present. Therefore, developing a renewable resource to produce aviation kerosene process is a matter related to people's livelihood and national security.

[0003] Carbon dioxide (CO2) is a greenhouse gas, and with the development of industry, the use of fossil fuels such as coal, oil and natural gas has increased the emission of carbon dioxide gas year by year. The increase of carbon dioxide emission aggravates the speed of global warming, which has obvious damage to the ecological environment of the earth, therefore, carbon dioxide emission reduction, storage and utilization are the research topics faced by scientists all over the world.

[0004] Patent application CN110975883A discloses a preparation of a dual-functional core-shell catalyst for carbon dioxide hydrogenation to aviation kerosene, which relates to the preparation of a core-shell catalyst, which is composed of four steps of synthesizing Cu-Fe / SiO2 catalytic core, synthesizing meso-TiO2@Cu-Fe / SiO2 core-shell catalyst, preparing meso-TiO2 precursor solution, and preparing meso-TiO2@Cu-Fe / SiO2 core-shell catalyst. Through core catalytic reaction, the shell reaction product CO is consumed in the catalytic system, and the reaction of the shell catalyst is moved to the positive reaction direction.

[0005] Patent application CN114307908A discloses a device and method for synthesizing liquid fuel by carbon dioxide multi-field synergistic catalytic hydrogenation, which is used for contacting a gas mixture of carbon dioxide and hydrogen with a catalyst to synthesize liquid fuel. The liquid fuel is a hydrocarbon and its mixture which is liquid at room temperature. The device can generate a synergistic composite field in the area where the reaction unit is located, which includes at least two of thermal field, microwave field, ultrasonic field and electric field. The synthesized liquid fuel is mostly gasoline or aviation fuel.

[0006] Patent application CN113649010A discloses a synthesis method of a supported iron-based catalyst for preparing liquid fuel by carbon dioxide hydrogenation. The invention designs to use multi-dimensional materials as carriers, load metal iron species, and realizes effective regulation and control of the iron-based catalyst by introducing electronic additives. The supported iron-based catalyst modified by electronic additives is obtained by rapid treatment under microwave heating. The invention avoids the use of solvents and heating methods by using dry chemical and microwave heating methods, and can quickly synthesize a supported iron-based catalyst with uniform dispersion. The presence of electronic additives can effectively promote the generation of active phases and improve the adsorption capacity of catalytic surface reaction molecules, providing a new idea for preparing high-value liquid fuel by carbon dioxide hydrogenation.

[0007] However, the above-mentioned catalysts disclosed in the prior art have low activity and low selectivity for C 8+ The selectivity of aviation kerosene product is still not ideal, and there is an urgent need for high-activity catalysts to improve the selectivity of C 8+ There is an urgent need for high-activity catalysts to improve the selectivity of aviation kerosene product. SUMMARY

[0008] In view of the deficiencies of the prior art, one of the purposes of the present invention is to provide a Fe-Cu catalyst. The Fe-Cu catalyst of the present invention has high activity, which can greatly improve the selectivity of C 8+ The selectivity of aviation kerosene product is still not ideal, and there is an urgent need for high-activity catalysts to improve the selectivity of C

[0009] To achieve the above-mentioned purposes, the technical solutions of the present invention are as follows:

[0010] A Fe-Cu catalyst, which comprises an iron-containing compound, copper, an electronic additive and a structural additive, wherein the iron-containing compound is a mixture of Fe3O4, Fe7C3 and Fe5C2, and the mass ratio of Fe3O4, Fe7C3 and Fe5C2 is 1:(0.5-2):(0.5-2), preferably 1:(0.6-1.5):(0.6-1.5), more preferably 1:(0.8-1.2):(0.8-1.2).

[0011] The Fe-Cu catalyst according to the present application, wherein the molar ratio of the iron-containing compound to copper is 10:(0.5-3) in terms of metal elements.

[0012] The Fe-Cu catalyst according to the present application, wherein the molar ratio of copper, the electron assistant and the structure assistant is (0.5-3):(0.1-3):(0.1-1).

[0013] The Fe-Cu catalyst according to the present application, wherein the electron assistant is Na and B, the molar ratio of Na / B is 50:(1-10), preferably 50:(2-5); the structure assistant is one or more of Co, Al, Mg, Si, Zn, Mn, Ga, Ca, Sr, Nd, Ti, Ce; wherein the electron assistant and the structure assistant exist in the form of simple substance or oxide.

[0014] Another object of the present application is to provide a preparation method of the Fe-Cu catalyst, comprising the following steps:

[0015] Step 1: mixing and grinding iron salt, copper salt and assistant precursor;

[0016] Step 2: adding solvent to the mixture after grinding, stirring and mixing uniformly to obtain a gel;

[0017] Step 3: drying and calcining the gel to obtain a catalyst precursor;

[0018] Step 4: activating the catalyst precursor in synthesis gas to obtain the Fe-Cu catalyst.

[0019] The preparation method according to the present application, wherein in step 1,

[0020] The iron salt is selected from one or more of ferric nitrate, ferric sulfate, ferric oxalate, ferrous sulfate, ferric ammonium citrate and ferric chloride;

[0021] The copper salt is selected from one or more of copper nitrate, copper sulfate, copper chloride, copper carbonate and basic copper carbonate;

[0022] The assistant precursor includes an electron assistant precursor and a structure assistant precursor, wherein the electron assistant precursor includes a precursor of electron assistant Na and a precursor of electron assistant B, wherein the precursor of electron assistant Na is selected from one or more of sodium nitrate, sodium carbonate, sodium bicarbonate, sodium hydroxide and sodium chloride, and the precursor of electron assistant B is selected from one or more of boric acid and boron oxide; the structure assistant precursor is selected from one or more of nitrate, carbonate, chloride, oxide and silicate of Co, Al, Mg, Si, Zn, Mn, Ga, Ca, Sr, Nd, Ti and Ce;

[0023] The molar ratio of the iron salt, the copper salt, the electron assistant precursor and the structure assistant precursor is 10:(0.5-3):(0.1-3):(0.1-1).

[0024] According to the preparation method, in step 2,

[0025] The solvent is selected from a mixture of an organic substance and water, wherein the volume ratio of the organic substance to water is 1:(0.1-1), and the organic substance is selected from one or more of citric acid, oxalic acid, tartaric acid, salicylic acid, urea, ethylene glycol, glycerol and glucose.

[0026] The mass ratio of the iron salt to the solvent is 1:(0.5-5).

[0027] According to the preparation method, in step 3,

[0028] The drying temperature is 60-120 DEG C, and the time is 2-12 h.

[0029] The calcination temperature is 350-600 DEG C, and the time is 3-6 h.

[0030] According to the preparation method, in step 4,

[0031] The synthesis gas is a mixed gas of H2 and CO, wherein the volume ratio of H2 to CO is (0.5-3):1, and the feed air speed is 3000-6000 h -1 (V / V).

[0032] The activation treatment temperature is 250-450 DEG C, the time is 8-16 h, and the pressure is 0.1-1.5 MPa.

[0033] Another object of the present application is to provide the use of the Fe-Cu catalyst for preparing aviation kerosene from carbon dioxide hydrogenation.

[0034] Advantages

[0035] The Fe-Cu catalyst of the present application is based on iron-copper bimetallic components, and an assistant is introduced to adjust the electronic properties of the active sites, and a dry physical mixing method assisted by an organic solvent is provided for preparing a catalyst for carbon dioxide hydrogenation to prepare C 8+ aviation fuel. The Fe-Cu catalyst of the present application has high activity, and can greatly improve the selectivity of C 8+ aviation kerosene products, wherein C 8+ The selectivity of aviation kerosene is as high as more than 50%, which provides a new idea for preparing high-value-added chemicals from carbon dioxide hydrogenation, and has good industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1X-ray diffraction (XRD) pattern of the Fe-Cu catalyst prepared in Example 1 of the present application is shown.

[0037] Figure 2 Mossbauer spectrum of the Fe-Cu catalyst prepared in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present application will be described in more detail below. Although the preferred embodiments of the present application are described below, it is understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0039] The described embodiments are only some of the embodiments of the present application, not all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in the present application are within the scope of protection of the present application.

[0040] The raw materials used in the following examples are all commercially available unless otherwise specified.

[0041] Preparation of the Fe-Cu catalyst of the present application

[0042] Example 1

[0043] 1) Accurately weigh 8.08 g of Fe(NO3)3·9H2O (0.02 mol), 0.499 g of Cu(NO3)2·3H2O (0.002 mol), 0.17 g of NaNO3 (0.002 mol), and 0.146 g of Co(NO3)2·6H2O (0.0005 mol) into a crucible, mix well and grind for 1 hour to obtain a powder mixture A;

[0044] 2) Accurately weigh 9.222 g of citric acid (0.048 mol) and 0.0062 g of boric acid, and dissolve them in 8.98 mL of deionized water to obtain solution B;

[0045] 3) Add solution B to mixture A, stir for 30 min to obtain a gel C;

[0046] 4) Heat gel C at 70°C for 2 h, and then calcine it in a muffle furnace at 450°C for 4 h to obtain a catalyst precursor;

[0047] 5) Treat the catalyst precursor obtained in 4) in a synthesis gas (H2 / CO = 1) for 12 h under the conditions of 340°C, 0.2 MPa, and 5000 h-1(V / V) to obtain a Fe-Cu catalyst. -1

[0048] The XRD analysis spectrum and Mossbauer spectrum data of the catalyst are shown in Figure 1 ,​Figure 2 and Table 1. From the XRD and Mossbauer results, it can be seen that the Fe-Cu catalyst contains Fe304, Fe7C3and Fe5C2, etc. iron-containing phases, and the proportions are 34.8%, 31.7%, and 28.8%, respectively.

[0049] Table 1. Mossbauer spectrum fitting data

[0050] IS (mm / s) QS (mm / s) H (T) Γ (mm / s) Area (%) Fe3O4(A) (Sextet (1)) 0.55 0.04 46.06 0.59 12.2 Fe3O4(B) (Sextet (2)) 0.21 -0.07 49.16 0.77 22.6 Fe5C2 (I) (Sextet (3)) 0.11 -0.23 9.64 0.84 9.9 Fe5C2(II)(Sextet(4)) 0.35 0.73 19.05 0.25 5.1 Fe5C2(III) (Sextet (5)) 0.11 -0.18 22.72 0.50 13.8 Fe7C3 (I) (Sextet (6)) 0.06 -0.27 19.48 0.52 16.1 Fe7C3(II)(Sextet (7)) 0.05 0.19 17.01 0.43 15.6 Doublet 0.05 1.00 — 0.57 4.8

[0051] Examples 2-7

[0052] According to the same preparation method as Example 1, the following conditions are adjusted to prepare the Fe-Cu catalysts of Examples 2-7. See Table 2 below for the specific condition adjustments. The XRD analysis spectrum and the Mossbauer spectrum of the catalysts prepared in Examples 2-7 are consistent with Example 1.

[0053]

[0054]

[0055] Preparation of Comparative Fe-Cu Catalysts

[0056] Comparative Example 1

[0057] 1) Accurately weigh 40.4 g of Fe(NO3)3·9H2O (0.1 mol) and 14.85 g of Cu(NO3)2(0.05 mol), and use deionized water to make up to 200 mL. After complete dissolution, obtain solution 1 for standby;

[0058] 2) Accurately weigh 21.2 g of anhydrous sodium carbonate (0.2 mol), and use deionized water to make up to 100 mL. After complete dissolution, obtain solution 2 for standby;

[0059] 3) Add 200 mL of deionized water to a four-necked flask, and fix it in a water bath with a temperature of 30°C and a stirring speed of 300 rpm. Then, add solution 1 and solution 2 to the four-necked flask using a peristaltic pump, and control the pH value of the mixed solution in the four-necked flask to be stable at 7.5±0.5;

[0060] 4) After the solution is completely added, continue stirring for 30 min, and then stand overnight for aging. Then, separate the filtrate and the slurry using a suction filter pump. The amount of deionized water used during the suction filtration process is 1000 mL. Finally, wash with 40 mL of ethanol. Dry the precipitate obtained after washing in an oven at 110°C for 12 h;

[0061] 5) Dry the solid obtained in 4) at 120°C for 12 h. Finally, transfer the obtained solid to a muffle furnace, and calcine at 450°C for 4 h to obtain the catalyst precursor;

[0062] 6) The catalyst precursor obtained in 5) was treated in synthesis gas (H2 / CO = 2) for 12 h, the treatment conditions being 300°C, 0.2 MPa, 5000 h -1 (V / V). Namely, the Fe-Cu catalyst was obtained, in which Fe was Fe5C2 and Cu was CuO.

[0063] Experimental Example

[0064] The Fe-Cu catalyst 1 g prepared in the above examples and comparative examples was respectively subjected to CO2 hydrogenation reaction in a fixed bed using reaction gas (H2 / CO2 = 3), the reaction conditions being 300°C, 1.5 MPa, 2500 h -1 (V / V), and the reaction results are shown in Table 3 below.

[0065] Table 3

[0066]

[0067]

[0068] As can be seen from Table 3, the catalyst provided by the present application has excellent catalytic activity, and can greatly improve the selectivity of C 8+ hydrocarbons, which is obviously superior to the comparative catalyst. Therefore, the catalyst provided by the present application has excellent catalytic activity, and can greatly improve the selectivity of C 8+ hydrocarbons, which is obviously superior to the comparative catalyst. Therefore, the catalyst provided by the present application has excellent catalytic activity, and can greatly improve the selectivity of C 8+ hydrocarbons, which is obviously superior to the comparative catalyst. Therefore, the catalyst provided by the present application has excellent catalytic activity, and can greatly improve the selectivity of C The selectivity of aviation kerosene is as high as 50% or more, which provides a new idea for preparing high-value-added chemicals from carbon dioxide and hydrogen, and has good prospects for industrial application.

Claims

1. A Fe-Cu catalyst, comprising an iron-containing compound, copper, an electronic promoter and a structural promoter, wherein the iron-containing compound is a mixture of Fe 3O 4, Fe 7C 3 and Fe 5C 2, and the mass ratio of Fe 3O 4, Fe 7C 3 and Fe 5C 2 is 1: (0.5-2) : (0.5-2).

2. The Fe-Cu catalyst according to claim 1, wherein, The molar ratio of the iron-containing compound to copper is 10: (0.5-3), based on metal elements.

3. The Fe-Cu catalyst according to claim 1 or 2, wherein, The molar ratio of copper, the electronic promoter and the structural promoter is (0.5-3) : (0.1-3) : (0.1-1).

4. The Fe-Cu catalyst according to any one of claims 1 to 3, wherein, The electronic promoter is Na and B, and the molar ratio of Na / B is 50: (1-10) ; the structural promoter is one or more of Co, Al, Mg, Si, Zn, Mn, Ga, Ca, Sr, Nd, Ti, Ce; and the electronic promoter and the structural promoter are in the form of an element or an oxide. 5.A method for preparing the Fe-Cu catalyst according to any one of claims 1-4, comprising the following steps: Step 1: mixing and grinding an iron salt, a copper salt and a promoter precursor; Step 2: adding a solvent to the mixture after grinding, stirring and mixing uniformly to obtain a gel; Step 3: drying and calcining the gel to obtain a catalyst precursor; Step 4: activating the catalyst precursor in a synthesis gas to obtain the Fe-Cu catalyst.

6. The production method according to claim 5, wherein In Step 1, the iron salt is selected from one or more of ferric nitrate, ferric sulfate, ferric oxalate, ferrous sulfate, ferric ammonium citrate and ferric chloride; the copper salt is selected from one or more of copper nitrate, copper sulfate, copper chloride, copper carbonate and basic copper carbonate; the promoter precursor comprises an electronic promoter precursor and a structural promoter precursor, wherein the electronic promoter precursor comprises a precursor of the electronic promoter Na and a precursor of the electronic promoter B, the precursor of the electronic promoter Na is selected from one or more of sodium nitrate, sodium carbonate, sodium bicarbonate, sodium hydroxide and sodium chloride, and the precursor of the electronic promoter B is selected from one or more of boric acid and boron oxide; and the structural promoter precursor is selected from one or more of nitrates, carbonates, chlorides, oxides and silicates of Co, Al, Mg, Si, Zn, Mn, Ga, Ca, Sr, Nd, Ti and Ce; the molar ratio of the iron salt, the copper salt, the electronic promoter precursor and the structural promoter precursor is 10: (0.5-3) : (0.1-3) : (0.1-1).

7. The production method according to claim 5 or 6, wherein In Step 2, the solvent is selected from a mixture of an organic compound and water, wherein the volume ratio of the organic compound to water is 1: (0.1-1), and the organic compound is selected from one or more of citric acid, oxalic acid, tartaric acid, salicylic acid, urea, ethylene glycol and glycerol; the mass ratio of the iron salt to the solvent is 1: (0.5-5).

8. The production process according to any one of claims 5 to 7, wherein In Step 3, the drying temperature is 60-120℃, and the drying time is 2-12h; the calcination temperature is 350-600℃, and the calcination time is 3-6h.

9. The production process according to any one of claims 5 to 8, wherein, In Step 4, The synthesis gas is a mixture of H2and CO, wherein the volume ratio of H2to CO is (0.5-3): 1, the feed space velocity is 3000-6000 h -1 (V / V); the activation temperature is 250-450℃, the activation time is 8-16h, and the pressure is 0.1-1.5MPa.

10. Use of the Fe-Cu catalyst according to any one of claims 1 to 4 or the Fe-Cu catalyst prepared according to any one of claims 5 to 9 for the production of aviation kerosene by the hydrogenation of carbon dioxide.

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