Composite metal oxide for synthesis of aromatic hydrocarbons from syngas and use thereof

Abstract

The application provides a composite metal oxide for synthesizing aromatic hydrocarbons from synthesis gas and application thereof; raw materials of the composite metal oxide include chromium salt, indium salt, iron salt, zinc salt and aluminum salt. The indium oxide of the composite metal oxide has high CO hydrogenation and reverse water gas shift reaction activity, can not only improve the activity of converting CO into oxygen-containing intermediates on the oxide, but also optimize product distribution, effectively reduce the CO2 selectivity in the product, and has high aromatic hydrocarbon selectivity; can catalyze synthesis gas to be converted into aromatic hydrocarbons, has low CO2 selectivity in by-products, high reaction efficiency, and the oxide is not easy to be deactivated. In addition, the composite metal oxide prepared by high-boiling-point organic solvent high-temperature decomposition of metal precursors is fast and simple, has a relatively stable structure, effectively inhibits the migration of metal to the molecular sieve, and greatly improves the reaction stability of synthesis gas for aromatic hydrocarbons.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aromatic hydrocarbon preparation, and particularly relates to a composite metal oxide for synthesizing aromatic hydrocarbons from synthesis gas and application thereof. BACKGROUND

[0002] Aromatic hydrocarbons are a class of essential basic chemical raw materials, which are currently mainly obtained from petroleum resources through naphtha reforming or petroleum cracking technology. However, with the increasing consumption of petroleum and the gradual depletion of petroleum resources, the preparation of aromatic hydrocarbons from non-petroleum resources (such as coal, natural gas, biomass and CO2) through synthesis gas (CO+H2) has shown great development potential. In the traditional conversion of synthesis gas to hydrocarbons, i.e., Fischer-Tropsch synthesis (FTS) reaction, the main products are chain hydrocarbons, and the distribution of these products follows the ASF rule, resulting in very low selectivity of aromatic hydrocarbons. In order to obtain more aromatic hydrocarbon products, another feasible strategy is to use a two-step method. Specifically, this method first converts synthesis gas into methanol through a methanol synthesis step, and then uses methanol-to-aromatics (MTA) to realize the conversion of synthesis gas to aromatic hydrocarbons. However, the two-step method has problems such as multiple processes and high energy consumption, which restricts its further industrialization.

[0003] In recent years, based on the reaction coupling strategy, by coupling the oxide for converting synthesis gas to methanol and the MTA molecular sieve, the high-selectivity conversion of synthesis gas to aromatic hydrocarbons has been successfully realized. However, this methanol-mediated route still has problems such as low CO conversion rate and high selectivity of byproduct CO2, and its reaction efficiency needs to be further improved. Patent CN202211202019.5 discloses a Mn-based metal oxide loaded with at least one of Ce, Zr, Ti, Fe and Ni, which is used in the synthesis gas-to-aromatics reaction, significantly improving the CO conversion rate and aromatic hydrocarbon yield. Patent CN202211314164.2 discloses a synthesis gas-to-aromatics catalyst with higher CO conversion rate and aromatic hydrocarbon selectivity, which includes at least one of ZnO, Cr2O3, ZrO2, MnO x , CeO2, Ga2O3, ZnTi, ZnZr, ZnCr, MnCe, MnZr and GaZr. Patent CN114588902A discloses a catalyst for the conversion of synthesis gas to aromatic hydrocarbons, a preparation method and application thereof. The catalyst uses a Fischer-Tropsch metal modified metal oxide, wherein the modified metal is at least one of Fe, Co, Ru and Ni, and wherein Fe, Co, Ru and Ni loaded on the composite oxide also have the effect of improving the conversion efficiency of synthesis gas.

[0004] Patent CN202110456312.3 discloses a preparation method of a synthetic gas to aromatic hydrocarbon catalyst composed of a silicon-aluminum molecular sieve and a complex phase metal oxide, wherein the complex phase metal oxide is at least two of cerium oxide-zirconium oxide, zinc oxide-chromium oxide, and zinc oxide-zirconium oxide. Patent CN202211179273.8 discloses a short-b-axis HZSM-5 zeolite molecular sieve, and a Zr-Zn metal oxide and a short-b-axis HZSM-5 zeolite are used to prepare aromatic hydrocarbons.

[0005] However, the doping of metal elements in the above patent documents can only improve the CO conversion rate in the synthesis gas conversion to aromatic hydrocarbons, and cannot significantly reduce the CO2 selectivity. In summary, the CO2 selectivity of the above catalysts is still high.

[0006] Therefore, it is of great significance to develop a synthetic gas conversion to aromatic hydrocarbon catalyst with high reaction efficiency and low CO2 selectivity. SUMMARY

[0007] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a preparation method of indium-doped high-entropy nanocomposite metal oxide and its application in synthetic gas to aromatic hydrocarbon, for solving the problems in the prior art. In order to achieve the above-mentioned purposes and other related purposes, the present application is obtained by the following technical solutions.

[0008] The present application provides a composite metal oxide, the raw materials of the composite metal oxide include chromium salt, indium salt, iron salt, zinc salt and aluminum salt.

[0009] In some embodiments, the molar ratio of chromium in the chromium salt to indium in the indium salt, iron in the iron salt, zinc in the zinc salt, and aluminum in the aluminum salt is 1:0.1-1:0.1-1:0.1-1:0.1-1.

[0010] In some embodiments, the molar ratio of chromium in the chromium salt to indium in the indium salt, iron in the iron salt, zinc in the zinc salt, and aluminum in the aluminum salt is 1:0.1-1:0.1-1:0.1-1:0.1-1.

[0011] In some embodiments, the molar ratio of chromium in the chromium salt to indium in the indium salt, iron in the iron salt, zinc in the zinc salt, and aluminum in the aluminum salt is 1:0.25-0.5:0.25-0.5:0.25-0.5:0.25-0.5.

[0012] In some embodiments, the molar ratio of the chromium salt to the chromium element, the indium element, the iron element, the zinc element and the aluminum element in the indium salt, the iron salt, the zinc salt and the aluminum salt can also be 1:0.5:0.25:0.5:0.5, 1:0.25:0.25:0.5:0.5 or 1:0.5:0.25:0.5:0.25.

[0013] In some embodiments, the chromium salt comprises at least one of chromium acetate, chromium acetylacetonate.

[0014] In some embodiments, the indium salt comprises at least one of indium acetate, indium acetylacetonate.

[0015] In some embodiments, the iron salt comprises at least one of iron acetate, iron acetylacetonate.

[0016] In some embodiments, the zinc salt comprises at least one of zinc acetate, zinc acetylacetonate.

[0017] In some embodiments, the aluminum salt comprises at least one of aluminum acetate, aluminum acetylacetonate.

[0018] In the above composite metal oxide, chromium oxide (chemical formula: Cr2O3), indium oxide (In2O3), iron oxide (Fe2O3), zinc oxide (ZnO), and aluminum oxide (Al2O3) are contained.

[0019] In some embodiments, the average grain size of the composite metal oxide is 5-7 nm; and the composite metal oxide is in a crystalline state.

[0020] In a second aspect of the present application, a preparation method of a composite metal oxide is provided, comprising the following steps:

[0021] S1: uniformly mixing and stirring an indium salt, an iron salt, an aluminum salt, a chromium salt, a zinc salt and a high-boiling organic solvent, and refluxing to obtain a reaction product;

[0022] S2: precipitating, washing and drying the reaction product to obtain the indium-doped oxide.

[0023] In some embodiments, the molar ratio of the chromium salt to the indium salt, the iron salt, the zinc salt and the aluminum salt is 1:0.1-1:0.1-1:0.1-1:0.1-1.

[0024] In some embodiments, the molar ratio of the chromium salt to the indium salt, the iron salt, the zinc salt and the aluminum salt is 1:0.1-0.6:0.1-0.6:0.1-0.6:0.1-0.6.

[0025] In certain embodiments, the molar ratio of the chromium salt to the indium salt, the iron salt, the zinc salt, the aluminum salt is 1:0.25-0.5:0.25-0.5:0.25-0.5:0.25-0.5.

[0026] In certain embodiments, the molar ratio of the chromium salt to the indium salt, the iron salt, the zinc salt, the aluminum salt can also be 1:0.5:0.25:0.5:0.5, 1:0.25:0.25:0.5:0.5, or 1:0.5:0.25:0.5:0.25.

[0027] In certain embodiments, the chromium salt comprises at least one of chromium acetate, chromium acetylacetonate.

[0028] In certain embodiments, the indium salt comprises at least one of indium acetate, indium acetylacetonate.

[0029] In certain embodiments, the iron salt comprises at least one of iron acetate, iron acetylacetonate.

[0030] In certain embodiments, the zinc salt comprises at least one of zinc acetate, zinc acetylacetonate.

[0031] In certain embodiments, the aluminum salt comprises at least one of aluminum acetate, aluminum acetylacetonate.

[0032] In certain embodiments, the high-boiling organic solvent is one or more of oleic acid, oleylamine, octadecanol, octadecene; wherein the high-boiling organic solvent functions as a solvent, a dispersant, and a surfactant.

[0033] In certain embodiments, the amount of the high-boiling organic solvent is 1 g of the chromium salt per 5-100 mL of the high-boiling organic solvent; it can also be 1 g of the chromium salt per 5-50 mL of the high-boiling organic solvent, it can also be 1 g of the chromium salt per 10-30 mL of the high-boiling organic solvent, it can also be 1 g of the chromium salt per 20-50 mL of the high-boiling organic solvent, it can also be 1 g of the chromium salt per 10 mL of the high-boiling organic solvent, it can also be 1 g of the chromium salt per 15 mL of the high-boiling organic solvent, it can also be 1 g of the chromium salt per 20 mL of the high-boiling organic solvent, it can also be 1 g of the chromium salt per 25 mL of the high-boiling organic solvent, it can also be 1 g of the chromium salt per 30 mL of the high-boiling organic solvent.

[0034] In certain embodiments, the temperature of the stirring is 70-90℃; it can also be 70-80℃, it can also be 80-90℃, it can also be 75-85℃, it can also be 70℃, 75℃, 80℃, 85℃, 90℃.

[0035] In some embodiments, the stirring time is 20-40 min; it can also be 20-30 min, 30-40 min, 25-35 min, 20 min, 25 min, 30 min, 35 min, or 40 min.

[0036] In some embodiments, the temperature of the heat refluxing is 150-400℃; it can also be 150-200℃, 200-250℃, 250-300℃, 300-350℃, 350-400℃, 200-300℃, 200-350℃; it can also be 150℃, 200℃, 250℃, 300℃, 350℃, or 400℃.

[0037] In some embodiments, the heat refluxing time is 1-3 h; it can also be 1.5-2.5 h, 1-2 h, or 2-3 h; it can also be 1 h, 1.5 h, 2 h, 2.5 h, or 3 h.

[0038] In some embodiments, the step of precipitating and washing the reaction product comprises the following steps: adding a detergent to the reaction product and mixing uniformly, then standing to produce a precipitate, and then collecting the precipitate after centrifuging and / or washing the precipitate one or more times using the detergent; wherein the detergent is used for precipitating and washing the reaction product. The amount of the detergent used is determined according to the specific experimental conditions and the properties of the precipitate, and is not specially limited. The standing time is 5-60 min; it can also be 5-30 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 50 min, or 60 min.

[0039] In some embodiments, the detergent comprises one or more of ethanol, ethylene glycol, methanol, or acetone.

[0040] In some embodiments, the centrifuging speed is 6000-10000 r / min; it can also be 7000-9000 r / min, 6000 r / min, 7000 r / min, 8000 r / min, 9000 r / min, or 10000 r / min.

[0041] In some embodiments, the centrifuging time is 4-15 min; it can also be 4-10 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, or 15 min.

[0042] In some embodiments, the drying temperature is 60-80℃; it can also be 65-75℃, it can also be 60-70℃, it can also be 70-80℃; it can also be 60℃, 65℃, 70℃, 75℃, 80℃.

[0043] In some embodiments, the drying time is 6-16h; it can also be 6-12h, it can also be 12-16h, it can also be 8-14h, it can also be 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h or 16h.

[0044] The present application also provides a bifunctional catalyst for preparing aromatic hydrocarbon, comprising the composite metal oxide as described above.

[0045] In some embodiments, the bifunctional catalyst further comprises a silicoaluminophosphate molecular sieve.

[0046] In some embodiments, the silicoaluminophosphate molecular sieve is a hydrogen-type silicoaluminophosphate molecular sieve.

[0047] In some embodiments, the silicoaluminophosphate molecular sieve has a Si / Al ratio of 20-500; it can also be 20-100; it can also be 100-200, it can also be 200-300, it can also be 300-400, it can also be 400-500; it can also be 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450 or 500.

[0048] In some embodiments, the molecular sieve is HZSM-5 molecular sieve.

[0049] In some embodiments, the mass ratio of the composite metal oxide and the silicoaluminophosphate molecular sieve is 0.25-3:1, it can also be 0.5-3:1; it can also be 0.5-2:1, it can also be 2-3:1, it can also be 3-4:1, it can also be 4-5:1, it can also be 0.5-1.5:1; it can also be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 2:1, 2.5:1 or 3:1.

[0050] The present application also provides a preparation method of the bifunctional catalyst as described above, comprising mixing the composite metal oxide as described above with a silicoaluminophosphate molecular sieve, to obtain the bifunctional catalyst.

[0051] In some embodiments, the mixing is followed by a step of tableting, granulating and / or sieving; preferably a step of sieving through a 40-60 mesh sieve; and can also be a 45-55 mesh sieve, and can also be a 40, 45, 50, 55 or 60 mesh sieve.

[0052] The present application also provides use of the composite metal oxide or bifunctional catalyst as described above in the preparation of aromatic hydrocarbons using synthesis gas as raw material.

[0053] In some embodiments, the synthesis gas is synthesis gas containing carbon monoxide and hydrogen, or synthesis gas containing carbon monoxide, carbon dioxide and hydrogen.

[0054] The present application also provides a method for preparing aromatic hydrocarbons, which comprises: contacting and reacting synthesis gas with the bifunctional catalyst as described above to obtain aromatic hydrocarbons.

[0055] In some embodiments, the bifunctional catalyst needs to be pretreated before being contacted with synthesis gas.

[0056] In some embodiments, the pretreatment is specifically heat treatment under H2 atmosphere; H2 pretreatment produces active sites - oxygen vacancies, but argon pretreatment (removes water and organic matter adsorbed on the catalyst, etc.) can also be used, because the reducing components (such as H2, CO, etc.) in the raw material gas can also be used to reduce part of the oxides to generate oxygen vacancies.

[0057] In some embodiments, the heat treatment temperature is 300-400°C, and can also be 300-350°C, 350-400°C, 320-380°C, 340-360°C, and can also be 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C or 400°C.

[0058] In some embodiments, the heat treatment time is 1-4h, and can also be 1-2h, 2-3h, 3-4h, 1-3h, 2-4h, and can also be 1h, 2h, 3h or 4h.

[0059] In some embodiments, the synthesis gas is synthesis gas containing carbon monoxide and hydrogen, or synthesis gas containing carbon monoxide, carbon dioxide and hydrogen.

[0060] In some embodiments, the synthesis gas contains carbon monoxide and hydrogen.

[0061] In certain embodiments, the molar ratio of carbon monoxide and hydrogen is 0.5-5:1, also 0.5-2:1, also 2-3:1, also 3-4:1, also 4-5:1, also 0.5-1.5:1; also 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1.

[0062] In certain embodiments, the mass hourly space velocity of the reaction is 300-2000 mL g cat -1 h -1 , also 300-500 mL g cat -1 h -1 , also 500-1000 mL g cat -1 h -1 , also 1000-1500 mL g cat -1 h -1 , also 1500-2000 mL g cat -1 h -1 , also 300-1000 mL g cat -1 h -1 , also 300, 400, 500, 500, 600, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700 or 1800 mL g cat -1 h -1 .

[0063] In certain embodiments, the pressure of the reaction is 1-5 MPa; also 1-2 MPa; also 2-3 MPa; also 3-4 MPa; also 4-5 MPa, also 1-3 MPa; also 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 MPa.

[0064] In certain embodiments, the temperature of the reaction is 300-400 °C; also 320-380 °C, also 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C or 400 °C.

[0065] Advantages:

[0066] The present application provides a preparation of indium-doped high-entropy nanocomposite metal oxide and its application in synthesis gas to aromatic hydrocarbon. In the present application, the indium oxide in the composite metal oxide has high CO hydrogenation and reverse water gas shift (RWGS) reaction activity, which not only improves the activity of the oxide in converting CO to oxygen-containing intermediates, but also optimizes the product distribution, effectively reduces the selectivity of CO2 in the product, and has high aromatic hydrocarbon selectivity.

[0067] In addition, due to the easy migration characteristics of indium elements, the active metal components in the catalyst prepared by the conventional methods in the art, such as coprecipitation, reverse coprecipitation, impregnation, sol-gel method, flame spray pyrolysis, atomization spray pyrolysis and solid phase sintering method, are easy to migrate, and the prepared oxide has a large particle size, which is not conducive to the exertion of catalytic activity; the present application uses high-boiling organic solvent to rapidly and simply prepare indium-doped high-entropy nanometer oxide by high-temperature decomposition of metal precursors, and the indium-doped high-entropy nanometer oxide can be used as a catalyst to form a bifunctional catalyst with a molecular sieve to catalyze the conversion of synthesis gas to aromatic hydrocarbon, and the indium-doped high-entropy catalyst has a stable structure, effectively inhibits the migration of metal to the molecular sieve, and greatly improves the stability of the synthesis gas to aromatic hydrocarbon reaction of the bifunctional catalyst; and overcomes the defects of high selectivity of byproduct CO2 and easy migration of active metal components in the prior art catalyst for catalyzing the conversion of synthesis gas to aromatic hydrocarbon. BRIEF DESCRIPTION OF DRAWINGS

[0068] Figure 1 XRD diffraction pattern of the composite oxide powder in Example 1.

[0069] Figure 2 SEM image of the composite oxide powder in Example 1. DETAILED DESCRIPTION

[0070] The following describes the embodiments of the present application by specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the specification.

[0071] Before further describing the specific embodiments of the present application, it should be understood that the scope of protection of the present application is not limited to the following specific embodiments; it should also be understood that the terms used in the embodiments of the present application are for describing the specific embodiments and are not intended to limit the scope of protection of the present application. The test methods in the following examples are not specified, and are usually carried out under conventional conditions, or under the conditions recommended by the manufacturers.

[0072] When the embodiments give a numerical range, it should be understood that, unless otherwise specified by the present application, both the end points of each numerical range and any number between the two end points can be selected. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, devices, materials used in the embodiments, any method, device and material of the prior art similar or equivalent to the method, device and material described in the embodiments of the present application can also be used to implement the present application according to the mastery of the prior art by those skilled in the art and the description of the present application.

[0073] The sources of the raw materials in the following embodiments are as follows:

[0074] Analytically pure indium acetate, iron acetylacetone, aluminum acetylacetone, chromium acetylacetone and zinc acetylacetone were purchased from Shanghai Reagent Co., Ltd. ZSM-5 molecular sieve (SiO2 / Al2O3=50) was purchased from Shanghai Fuyu New Material Technology Co., Ltd.

[0075] The room temperature described in the present application is the conventional understanding of room temperature in the art, generally referring to 10-30℃.

[0076] Example 1

[0077] 0.29g (1mmol) of indium acetate, 0.18g (0.5mmol) of iron acetylacetone, 0.32g (1mmol) of aluminum acetylacetone, 0.71g (2mmol) of chromium acetylacetone, and 0.26g (1mmol) of zinc acetylacetone were mixed and dissolved in 50mL of oleylamine, heated to 80℃ and stirred for 30min, and then the reaction system was heated to 250℃ and stirred for 2h. After the reaction was completed, the temperature was cooled to room temperature, 50mL of ethanol was added to produce a precipitate, the precipitate was collected by centrifugation (8000r / min, 5min), and then washed with ethanol several times and dried in a 100℃ oven for 12h to obtain indium-doped high-entropy nano-oxide powder (the average grain size was about 5nm).

[0078] The indium-doped high-entropy nano-oxide and hydrogen-type ZSM-5 molecular sieve powder were physically ground and mixed according to a mass ratio of 1:1, tablet granulation was performed, and after crushing and sieving, a 40-60 mesh bifunctional catalyst was obtained.

[0079] Example 2

[0080] 0.15 g (0.5 mmol) of indium acetate, 0.18 g (0.5 mmol) of iron acetylacetonate, 0.32 g (1 mmol) of aluminum acetylacetonate, 0.71 g (2 mmol) of chromium acetylacetonate, and 0.26 g (1 mmol) of zinc acetylacetonate were mixed and dissolved in 50 mL of oleylamine, heated and stirred at 80°C for 30 min, and then the reaction system was heated and stirred at 250°C for 2 h after being warmed to reflux. After the reaction was completed, the reaction system was cooled to room temperature, 50 mL of ethanol was added, and the mixture was stirred for 10 min to produce a precipitate. The precipitate was collected by centrifugation (8000 r / min, 5 min), washed with ethanol, and dried in a 100°C oven for 12 h to obtain indium-doped high-entropy nanocomposite oxide powder (the average grain size was about 5 nm).

[0081] The indium-doped high-entropy nanocomposite oxide and hydrogen-type ZSM-5 molecular sieve powder were mixed in a mass ratio of 1:1, tableted and granulated, crushed and sieved to 40-60 mesh to obtain a bifunctional catalyst.

[0082] Example 3

[0083] 0.15 g (0.5 mmol) of indium acetate, 0.18 g (0.5 mmol) of iron acetylacetonate, 0.32 g (1 mmol) of aluminum acetylacetonate, 0.71 g (2 mmol) of chromium acetylacetonate, and 0.26 g (1 mmol) of zinc acetylacetonate were mixed and dissolved in 50 mL of oleylamine, heated and stirred at 80°C for 30 min, and then the reaction system was heated and stirred at 250°C for 2 h after being warmed to reflux. After the reaction was completed, the reaction system was cooled to room temperature, 50 mL of ethanol was added, and the mixture was stirred for 10 min to produce a precipitate. The precipitate was collected by centrifugation (8000 r / min, 5 min), washed with ethanol, and dried in a 100°C oven for 12 h to obtain indium-doped high-entropy nanocomposite oxide powder (the average grain size was about 5 nm).

[0084] The indium-doped high-entropy nanocomposite oxide and hydrogen-type ZSM-5 molecular sieve powder were mixed in a mass ratio of 1:1, tableted and granulated, crushed and sieved to 40-60 mesh to obtain a bifunctional catalyst.

[0085] Comparative Example 1

[0086] The 0.18 g (0.5 mmol) of iron acetylacetonate, 0.32 g (1 mmol) of aluminum acetylacetonate, 0.71 g (2 mmol) of chromium acetylacetonate, and 0.26 g (1 mmol) of zinc acetylacetonate were mixed and dissolved in 50 mL of oleylamine, heated and stirred at 80°C for 30 min, and then the reaction system was heated and stirred at 250°C for 2 h after being warmed to reflux. After the reaction was completed, the reaction system was cooled to room temperature, 50 mL of ethanol was added, and the mixture was stirred for 10 min to produce a precipitate. The precipitate was collected by centrifugation (8000 r / min, 5 min), washed with ethanol several times, and then dried in a 100°C oven overnight to obtain an indium-free doped nanometer composite oxide powder (the average size of the crystal grains was about 5 nm).

[0087] The above indium-doped nanometer oxide and hydrogen-type ZSM-5 molecular sieve powder were mixed in a mass ratio of 1:1, tableted and granulated, crushed and sieved to obtain a bifunctional catalyst with a particle size of 40-60 mesh.

[0088] Comparative Example 2

[0089] The 0.29 g (1 mmol) of indium acetate, 0.32 g (1 mmol) of aluminum acetylacetonate, 0.71 g (2 mmol) of chromium acetylacetonate, and 0.26 g (1 mmol) of zinc acetylacetonate were mixed and dissolved in 50 mL of oleylamine, heated and stirred at 80°C for 30 min, and then the reaction system was heated and stirred at 250°C for 2 h after being warmed to reflux. After the reaction was completed, the reaction system was cooled to room temperature, 50 mL of ethanol was added, and the mixture was stirred for 10 min to produce a precipitate. The precipitate was collected by centrifugation (8000 r / min, 5 min), washed with ethanol several times, and then dried in a 100°C oven for 12 h to obtain an indium-doped nanometer composite oxide powder (the average size of the crystal grains was about 5 nm) without iron.

[0090] The above indium-doped nanometer oxide and hydrogen-type ZSM-5 molecular sieve powder were mixed in a mass ratio of 1:1, tableted and granulated, crushed and sieved to obtain a bifunctional catalyst with a particle size of 40-60 mesh.

[0091] Comparative Example 3

[0092] 0.29 g (1 mmol) of indium acetate, 0.18 g (0.5 mmol) of iron acetylacetonate, 0.71 g (2 mmol) of chromium acetylacetonate, and 0.26 g (1 mmol) of zinc acetylacetonate were mixed and dissolved in 50 mL of oleylamine, heated to 80°C and stirred for 30 min, and then the reaction system was heated to 250°C and stirred for 2 h after being refluxed. After the reaction was completed, the system was cooled to room temperature, 50 mL of ethanol was added, and the mixture was stirred uniformly. After standing for 10 min, a precipitate was generated, which was collected by centrifugation (8000 r / min, 5 min), washed with ethanol several times, and then dried in a 100°C oven for 12 h to obtain indium-doped nano-oxide powder (the average size of the crystal grains was about 5 nm) without aluminum.

[0093] The indium-doped nano-oxide and hydrogen-type ZSM-5 molecular sieve powder were mixed in a mass ratio of 1:1 by physical grinding, tabletting and granulation, crushed and sieved to obtain a bifunctional catalyst with a particle size of 40-60 mesh.

[0094] Example 1

[0095] 1. The composite oxide obtained in Example 1 was subjected to X-ray diffraction (XRD) analysis to detect whether the composite oxide was in a crystalline state, and the specific steps were as follows:

[0096] A Rigatku Ultima IV X-ray diffractometer was used to study the crystallization and crystal phase properties of the oxide sample. The tube voltage was set to 40 kV, the tube current was set to 40 mA, and the "Cu Kα X-ray" was selected as the X-ray diffractometer equipment ray source. The tube voltage was set to 40 kV, the tube current was set to 40 mA, and the "Cu Kα X-ray" was selected as the X-ray diffractometer equipment ray source. The 2θ range was 5-90°, and the scanning step was 2°. The crystal phase data of the oxide was collected.

[0097] The results are shown in Figure 1 It can be seen that the XRD pattern of the composite oxide has diffraction peaks with different diffraction intensities, which is a crystalline state, not amorphous.

[0098] 2. The composite oxide powder obtained in Example 1 was subjected to transmission electron microscopy (TEM) characterization (the instrument model was Tecnai G2 S-Twin, and the working voltage was 200 kV), and the results are shown in Figure 2 .

[0099] The X-ray diffraction (XRD) analysis pattern of the composite oxide obtained in Example 1 is shown in Figure 1The average size of the crystal grains was calculated using the Jade software (for analyzing XRD patterns) by the Scherrer formula:

[0100] Scherrer formula: D = Kλ / (βcosθ), K is a constant;

[0101] D is the average thickness of the crystal grains perpendicular to the crystal face direction, λ is the X-ray wavelength; β is the half-height width of the diffraction peak; and θ is the diffraction angle. In the above formula, the value of the constant K is related to the definition of β. When β is the half-height width, K is 0.89; and when β is the integral width, K is 1.0.

[0102] The average size of the composite oxide calculated based on the Scherrer formula is about 5 nm, specifically 5-7 nm.

[0103] Example 2

[0104] The bifunctional catalysts obtained in Examples 1-3 and Comparative Examples 1-3 were tested, and the testing method was as follows:

[0105] 1 g of the catalyst (40-60 mesh) was loaded in a fixed bed reactor, and the catalyst was pretreated at 350°C under H2 atmosphere for 1-4 h before the raw material gas was introduced. The raw material gas was a synthesis gas (a mixture of CO, H2 and N2, wherein N2 was an internal standard, and the corresponding volume contents of CO, H2 and N2 were 48%, 48% and 4%, respectively), the reaction temperature was 350°C, the reaction pressure was 2 MPa, and the mass space velocity (under standard conditions) was 600 mL / g cat / h.

[0106] The tail gas flowed through a pipeline for heat preservation and was transported to a gas chromatograph in a gaseous state for online analysis. The chromatograph was equipped with a thermal conductivity detector and a packed chromatographic column, and a hydrogen flame ionization detector (FID) and a capillary column, wherein the former was used to detect H2, N2, CO and CO2, and the latter was used to detect the composition of hydrocarbon products. The CO conversion rate was calculated with N2 as an internal standard, and the distribution of hydrocarbon products was calculated in terms of carbon moles; the results are shown in Table 1.

[0107] Table 1

[0108]

[0109]

[0110] Notes, in Table 1:

[0111] 1) The reaction temperature refers to the reaction temperature of the catalyst when the catalyst catalyzes the raw material gas during the application of the catalyst.

[0112] 2) The conversion rate of CO (CO conv.%) is the ratio of the volume of CO reacted to the total volume of CO introduced.

[0113] 3) The CO2 selectivity (CO2 Sel.%) data are calculated based on all reaction products.

[0114] CO2 Sel.%=CO2 outlet / (CO inlet -CO outlet )*100%, of which CO2 outlet The volume of CO2 in the reaction tail gas is given by CO. inlet and CO outlet These represent the volume of CO reacted and the volume of CO introduced, respectively.

[0115] 4) Selectivity of hydrocarbon products (excluding CO2) (C n H m Sel. = 100% - CO2 sel.).

[0116] 5) The selectivity of CH4 (CH4 Sel.%) data is CH4 Sel.% = CH4 outlet / C n H m *100 is calculated, where CH4 outlet C represents the number of carbon moles in CH4 in the reaction tail gas. n H m It refers to the total amount of all hydrocarbons in the reactants, including methane, aromatics, and other hydrocarbons.

[0117] 6) Aromatic selectivity (aromatic Sel.%) data are based on the obtained hydrocarbon products, expressed as follows: Aromatic Sel.% = Aromatic outlet / C n H m Calculations show that aromatic hydrocarbons outlet C represents the total number of carbon moles of aromatic products in the reaction tail gas. n H m It refers to the total amount of all hydrocarbons in the reactants, including methane, aromatics, and other hydrocarbons.

[0118] 7) Selectivity of other products (Other Sel.%) refers to the selectivity of products from hydrocarbons other than methane and aromatics (including C2-C5 hydrocarbons or non-aromatic hydrocarbons larger than C5); Other Sel.% = Other outlet / C n H m Calculations show that the others outlet C represents the total number of carbon moles in the other products of the reaction tail gas. n H mTotal amount of all hydrocarbons in the reactants, including methane, aromatics, and other hydrocarbons.

[0119] The selectivity data of aromatics and other products are calculated based on the obtained hydrocarbon products, excluding oxygen-containing gas products such as CO2.

[0120] 8) Deactivation rate (% / d): The average decrease in CO conversion rate within the first 5 days of the reaction.

[0121] In summary, compared with Comparative Examples 1-3, the bifunctional catalysts of Examples 1-3 have a lower selectivity of by-product CO2 (less than 30%) and a significantly lower deactivation rate under the same reaction conditions (350°C, 2 MPa, and 600 mL / g cat / h) with a high reaction efficiency.

[0122] The above examples are only illustrative of the principles and effects of the present application, and are not intended to limit the present application. Any person skilled in the art can modify or change the above examples without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present application should be covered by the claims of the present application.

Claims

1. Use of a catalyst for the production of aromatic hydrocarbons from a synthesis gas as a feedstock, characterized in that, The catalyst comprises a composite metal oxide and a silicon-aluminum molecular sieve; raw materials of the composite metal oxide comprise a chromium salt, an indium salt, an iron salt, a zinc salt, and an aluminum salt; and the composite metal oxide is a high-entropy nanocomposite metal oxide. The molar ratio of chromium, indium, iron, zinc, and aluminum in the chromium salt, the indium salt, the iron salt, the zinc salt, and the aluminum salt is 1:0.1-1:0.1-1:0.1-1:0.1-1.

2. Use according to claim 1, characterized in that, The chromium salt comprises at least one of chromium acetate and chromium acetylacetone; and / or, The indium salt comprises at least one of indium acetate and indium acetylacetone; and / or, The iron salt comprises at least one of iron acetate and iron acetylacetone; and / or, The zinc salt comprises at least one of zinc acetate and zinc acetylacetone; and / or, The aluminum salt comprises at least one of aluminum acetate and aluminum acetylacetone; and / or, The molar ratio of the chromium salt, the indium salt, the iron salt, the zinc salt, and the aluminum salt is 1:0.1-1:0.1-1:0.1-1:0.1-1.

3. Use according to claim 1, characterized in that, The average grain size of the composite metal oxide is 5-7 nm; and / or, the composite metal oxide is in a crystalline state.

4. Use according to claim 1, characterized in that, The preparation method of the composite metal oxide comprises the following steps: S1: uniformly mixing the indium salt, the iron salt, the aluminum salt, the chromium salt, the zinc salt, and a high-boiling organic solvent, and refluxing to obtain a reaction product; S2: obtaining the composite metal oxide by precipitating, washing, and drying the reaction product.

5. Use according to claim 4, characterized in that, The high-boiling organic solvent is one or more of oleic acid, oleylamine, octadecanol, and octadecene; And / or, the amount of the high-boiling organic solvent is 1 g of the chromium salt per 5-100 mL of the high-boiling organic solvent; And / or, the temperature of the stirring is 70-90°C; and / or, the time of the stirring is 20-40 min; And / or, the temperature of the refluxing is 150-400°C; And / or, the time of the refluxing is 1-3 h; And / or, the specific steps of precipitating and washing the reaction product comprise: adding a washing agent to the reaction product to generate a precipitate, and then collecting the precipitate after centrifugation and / or washing of the precipitate using the washing agent.

6. Use according to claim 5, characterized in that, The washing agent comprises one or more of ethanol, ethylene glycol, methanol, and acetone; And / or, the centrifugation and / or washing comprises one or more times of centrifugation and / or washing; And / or, the speed of each centrifugation is 6000-10000 r / min; and / or, the time of each centrifugation is 4-15 min.

7. Use according to claim 1, characterized in that, The mass ratio of the composite metal oxide to the silicon-aluminum molecular sieve is 0.25-3:

1.

8. Use according to claim 1, characterized in that, The silicon-aluminum ratio of the silicon-aluminum molecular sieve is 20-500.

9. Use according to claim 7, characterized in that, The silicon-aluminum molecular sieve is a hydrogen-type silicon-aluminum molecular sieve.

10. Use according to claim 9, characterized in that, The molecular sieve is HZSM-5.

11. Use according to claim 1, characterized in that, The preparation method of the catalyst comprises mixing the composite metal oxide with the silicon-aluminum molecular sieve.

12. Use according to claim 11, characterized in that, The mixing further comprises a step of passing through a 40-60 mesh sieve.

13. Use according to claim 1, characterized in that, The synthesis gas is a synthesis gas containing carbon monoxide and hydrogen, or a synthesis gas containing carbon monoxide, carbon dioxide, and hydrogen.

14. Use according to claim 13, characterized in that, The synthesis gas comprises carbon monoxide and hydrogen.

15. Use according to claim 14, characterized in that, The molar ratio of carbon monoxide to hydrogen is 0.5-5:

1.

16. Use according to claim 1, characterized in that, The method for preparing the aromatic hydrocarbon comprises: contacting and reacting the synthesis gas with a catalyst to obtain the aromatic hydrocarbon.

17. Use according to claim 16, characterized in that, The catalyst needs to be heat-treated under H2 or argon atmosphere before being contacted with the synthesis gas; and / or the mass space velocity of the reaction is 300-2000 mL / g cat / h; And / or, the reaction pressure is 1-5 MPa; And / or, the reaction temperature is 300-400 ℃.

18. Use according to claim 17, characterized in that, The heat-treatment temperature is 300-400 ℃; and / or, the heat-treatment time is 1-4 h.

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