Composite oxide catalyst, method for producing the same, and use thereof

Abstract

The present application relates to the technical field of catalyst, in particular to a kind of composite oxide catalyst and its preparation method and use.The raw material of the composite oxide catalyst includes Fe-based catalyst, CuZr-based catalyst and first carrier;With the total mass of the raw material of the composite oxide catalyst as benchmark, the content of the Fe-based catalyst is 20wt%-80wt%, the content of the CuZr-based catalyst is 15wt%-79wt%, and the content of the first carrier is 1wt%-5wt%.Fe-based catalyst and CuZr-based catalyst in the composite oxide catalyst of the present application synergistically make the catalyst show high activity in the reaction of preparing ethanol by carbon dioxide hydrogenation, and also show high ethanol selectivity under the condition of high conversion rate, can obtain high-purity single ethanol product, can greatly reduce the cost of separation, improve economic benefit, and have broad market application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a composite oxide catalyst and a preparation method and use thereof. BACKGROUND

[0002] With the growing demand for energy and resources with social development, fossil energy such as coal, natural gas, oil is being consumed and a large amount of carbon dioxide is released into the air, thereby causing a series of natural and social problems.

[0003] By catalyzing carbon dioxide hydrogenation, carbon dioxide can be converted into chemicals with high added value, such as methanol, ethanol, urea, carbonate, etc. At the current market price, the price of methanol is 2525 yuan / ton, and the price of ethanol is 5950 yuan / ton. Obviously, ethanol has higher value than methanol. In the prior art, there are mainly three methods for industrial preparation of ethanol: ① hydration method; ② biological fermentation method; ③ direct catalysis of synthesis gas (CO+H2). The hydration method and the biological fermentation method have relatively high cost and more side reactions, and the direct catalysis of synthesis gas can effectively utilize coal resources, but still has problems such as more side reactions, low product selectivity, etc. Carbon dioxide hydrogenation reaction needs more hydrogen, and C-C coupling is more difficult to occur in the surface reaction process than synthesis gas, and it is easier to generate low-carbon products and oxygen-containing products, which can effectively improve the ethanol yield, and as a new method for preparing ethanol has great potential.

[0004] The current focus of carbon dioxide hydrogenation to prepare ethanol is to develop catalysts with high activity, high selectivity and good stability. Based on the literature reported, the catalysts for syngas to ethanol can be divided into the following three categories: ① noble metal catalysts, mainly Rh-based, Pd-based and Au-based catalysts, etc. Noble metals are usually supported on carriers with oxygen vacancies to compensate for the poor ability of noble metals to activate carbon dioxide. Typical patents include CN202110440016.4, CN201910424660.5, CN201811355101.5 and CN201610990095.5, and typical literature includes Angew Chem Int Ed, 63, 2024, e20246761; Angew Chem Int Ed, 61, 2022, e202210991. However, due to the high price of noble metals, the preparation cost of the catalyst is too high, and the metal content of the supported catalyst is low. Although the selectivity of ethanol can reach nearly 100%, the conversion rate is low, which is not conducive to large-scale production. ② Modified Cu-based catalysts: The synthesis of ethanol includes the activation, dissociation of carbon dioxide and the coupling of surface carbon species. The modified Cu-based catalysts can strengthen carbon-carbon coupling by adding alkali metals or other metals, which can change the product from methanol to ethanol. Typical patents include CN202111180718.X. However, the alcohol distribution of the modified Cu-based catalyst is still relatively wide, making it difficult to obtain high-purity ethanol. ③ Modified Co and Fe-based catalysts: By adjusting the additives and active phases, catalysts with high activity and high ethanol selectivity can be obtained. Typical patents include CN201810137781.7, and typical literature includes Angew Chem Int Ed, 135, 2023, e202311786; Angew Chem Int Ed, 57, 2018, 6104. However, the proportion of ethanol in the alcohol produced by the modified Co or Fe-based catalyst is often difficult to exceed 80%.

[0005] Currently, Fe-based non-noble metal catalysts also exhibit good performance in carbon dioxide hydrogenation to prepare ethanol, and due to the low price, large reserves and easy availability of active component metal Fe, as well as high catalytic activity, it is considered to be an ethanol catalyst with industrial prospects. However, like other non-noble metal catalysts, the Fe-based catalyst has low ethanol selectivity and low yield. How to improve the activity and selectivity of carbon dioxide hydrogenation to prepare ethanol through rational design of Fe-based catalysts is a major challenge at present. SUMMARY

[0006] In view of the above-mentioned disadvantages of the prior art, the present application aims to provide a composite oxide catalyst, a preparation method and use thereof. The composite oxide catalyst of the present application has a synergistic effect of Fe-based catalyst and CuZr-based catalyst, so that the catalyst exhibits high activity in the synthesis reaction of ethanol, high ethanol selectivity under high conversion rate, and high-purity single ethanol product, which greatly reduces the cost of separation and improves economic benefits.

[0007] To achieve the above-mentioned objects and other related objects, the first aspect of the present application provides a composite oxide catalyst.

[0008] The raw materials of the composite oxide catalyst include Fe-based catalyst, CuZr-based catalyst and a first carrier; the content of the Fe-based catalyst is 20-80wt%, the content of the CuZr-based catalyst is 15-79wt%, and the content of the first carrier is 1-5wt%, based on the total mass of the raw materials of the composite oxide catalyst.

[0009] The content of the Fe-based catalyst can be 20-24wt%, 24-35wt%, 35-40wt%, 40-48wt%, 48-50wt%, 50-55wt%, 55-67wt%, 67-75wt%, or 75-80wt%.

[0010] The content of the CuZr-based catalyst can be 15-20wt%, 20-23.6wt%, 23.6-30wt%, 30-41wt%, 41-49wt%, 49-50wt%, 50-55wt%, 55-62wt%, 62-70wt%, or 70-79wt%.

[0011] The content of the first carrier can be 1-2wt%, 2-3wt%, 3-4wt%, or 4-5wt%.

[0012] Preferably, the content of the Fe-based catalyst is 24-75wt%.

[0013] Preferably, the content of the CuZr-based catalyst is 23.6-62wt%.

[0014] Preferably, the first carrier is selected from one or more of SiO2, TiO2, and Al2O3.

[0015] More preferably, the first carrier is selected from one or more of fumed SiO2, fumed Al2O3, fumed TiO2, liquid silica sol, TiO2 aerosol, and Al2O3 aerosol.

[0016] Preferably, the Fe-based catalyst comprises Fe oxide and other oxides, the content of the Fe oxide is 15wt% to 75wt% and the content of the other oxides is 25wt% to 85wt% based on the mass of the Fe-based catalyst, the other oxides comprise a first metal oxide, the first metal is selected from one or more of alkali metal, alkaline earth metal, transition metal, rare earth metal and Group IIIA metal.

[0017] The content of the Fe oxide can be 15wt% to 15.8wt%, 15.8wt% to 25wt%, 25wt% to 30.5wt%, 30.5wt% to 37.6wt%, 37.6wt% to 48wt%, 48wt% to 55wt%, 55wt% to 65wt%, 65wt% to 75wt%.

[0018] The content of the other oxides can be 25wt% to 29wt%, 29wt% to 41wt%, 41wt% to 51.2wt%, 51.2wt% to 62.4wt%, 62.4wt% to 69.5wt%, 69.5wt% to 75wt%, 75wt% to 84.2wt%, 84.2wt% to 85wt%.

[0019] More preferably, the content of the Fe oxide is 15.8wt% to 71wt%.

[0020] More preferably, the content of the other oxides is 29wt% to 84.2wt%.

[0021] More preferably, the Fe oxide is Fe3O4.

[0022] More preferably, the other oxides further comprise a second carrier, the second carrier is selected from one or more of SiO2, TiO2, Al2O3.

[0023] More preferably, the alkaline earth metal is selected from one or more of Mg, Ca and Ba.

[0024] More preferably, the transition metal is selected from one or more of Mn, Co, Zr, Cu and Zn.

[0025] More preferably, the rare earth metal is selected from one or both of La and Ce.

[0026] More preferably, and / or, the Group IIIA metal is selected from one or both of Al and In.

[0027] Preferably, the CuZr-based catalyst comprises CuZr oxide and a second metal oxide, the content of the CuZr oxide is 20wt% to 85wt% and the content of the second metal oxide is 15wt% to 80wt% based on the mass of the CuZr-based catalyst, and the second metal is selected from one or more of Zn, Al, Mg and Mn.

[0028] The content of the CuZr oxide can be 20wt% to 30wt%, 30wt% to 36wt%, 36wt% to 45wt%, 45wt% to 55wt%, 55wt% to 61.4wt%, 61.4wt% to 67.9wt%, 67.9wt% to 75wt%, 75wt% to 81wt%, 81wt% to 85wt%.

[0029] The content of the second metal oxide can be 15wt% to 19wt%, 19wt% to 25wt%, 25wt% to 32.1wt%, 32.1wt% to 38.6wt%, 38.6wt% to 45wt%, 45wt% to 55wt%, 55wt% to 64wt%, 64wt% to 70wt%, 70wt% to 80wt%.

[0030] More preferably, the content of the CuZr oxide is 20.2wt% to 81wt%.

[0031] More preferably, the content of the second metal oxide is 19wt% to 79.8wt%,

[0032] More preferably, the molar ratio of Cu to Zr in the CuZr oxide is (5 to 20):1. The molar ratio of Cu to Zr in the CuZr oxide can be (5 to 6):1, (6 to 10):1, (10 to 15):1, (15 to 20):1.

[0033] Further, the molar ratio of Cu to Zr in the CuZr oxide is (6 to 20):1.

[0034] The second aspect of the present application discloses a preparation method of the composite oxide catalyst as above, which comprises the following steps:

[0035] a1) mixing the first carrier, the Fe-based catalyst and the CuZr-based catalyst to obtain a solid mixture;

[0036] a2) calcining the solid mixture to obtain the composite oxide catalyst.

[0037] Preferably, in the step a2), the temperature of the calcination is 200-500℃. For example, the temperature of the calcination can be 200-250℃, 250-300℃, 300-350℃, 350-400℃, 400-450℃, 450-500℃.

[0038] Preferably, in the step a2), the time of the calcination is 2h-10h. For example, the time of the calcination can be 2-3h, 3-4h, 4-5h, 5-6h, 6-7h, 7-8h, 8-9h, 9-10h.

[0039] Preferably, the method for preparing the Fe-based catalyst comprises:

[0040] b1) dissolving the Fe oxide and the soluble salt of the first metal oxide except alkali metal in water to obtain solution B;

[0041] b2) dissolving a precipitant in water to obtain solution C;

[0042] b3) simultaneously dropping the solution B and the solution C into water for co-precipitation until no more precipitate is produced;

[0043] b4) after the co-precipitation, aging is performed to obtain solution D;

[0044] b5) performing solid-liquid separation on the solution D, washing and drying the solid product obtained by the solid-liquid separation, and calcining to obtain the Fe-based catalyst without alkali metal.

[0045] More preferably, in the step b3), the mother liquor further disperses a second carrier.

[0046] More preferably, after the step b5), impregnation is further included, the solution for the impregnation is an aqueous solution of the soluble salt of the alkali metal, after the impregnation, the operation of the step b5) is repeated, and the concentration of the aqueous solution of the soluble salt of the alkali metal is 0.1-5mol / L.

[0047] More preferably, in the step b1), the molar concentration of the solution B is 0.1-5mol / L. For example, the molar concentration of the solution B can be 0.1-0.5mol / L, 0.5-1mol / L, 1-2mol / L, 2-3mol / L, 3-4mol / L, 4-5mol / L.

[0048] More preferably, in the step b1), the soluble salt is selected from one or more of chloride, nitrate, sulfate, carbonate or acetate.

[0049] More preferably, in the step b2), the concentration of the solution C is 0.1-5 mol / L. For example, the molar concentration of the solution C can be 0.1-0.2 mol / L, 0.2-1 mol / L, 1-2 mol / L, 2-3 mol / L, 3-4 mol / L, 4-5 mol / L.

[0050] More preferably, in the step b2), the precipitant is one or more selected from Na2CO3, K2CO3, (NH4)2CO3, NaOH, KOH and NH3·H2O.

[0051] More preferably, in the step b3), the mother liquor is water.

[0052] More preferably, in the step b3), the temperature of the co-precipitation is 30-100℃. For example, the temperature of the co-precipitation can be 30-40℃, 40-50℃, 50-60℃, 60-70℃, 70-80℃, 80-100℃.

[0053] More preferably, in the step b3), the pH of the mother liquor during the co-precipitation is 7-12. For example, the pH of the mother liquor during the co-precipitation can be 7-7.5, 7.5-8.5, 8.5-9.5, 9.5-10, 10-11, 11-12.

[0054] Further, in the step b3), the solution B and the solution C are dropped into water in a parallel flow manner, and the dropping speed is controlled so that the pH of the mother liquor during the co-precipitation is maintained at 7-12.

[0055] More preferably, in the step b4), the temperature of the aging is 30-100℃. For example, the temperature of the aging can be 30-40℃, 40-50℃, 50-60℃, 60-70℃, 70-80℃, 80-100℃.

[0056] More preferably, in the step b4), the time of the aging is 2-48 h. For example, the time of the aging can be 2-4 h, 4-10 h, 10-12 h, 12-18 h, 18-24 h, 24-30 h, 30-36 h, 36-42 h, 42-48 h.

[0057] More preferably, in the step b5), the temperature of the drying is 100-150℃. For example, the temperature of the drying can be 100-110℃, 110-120℃, 120-130℃, 130-140℃, 140-150℃.

[0058] More preferably, in the step b5), the drying time is 6-24h. The drying time can be 6-12h, 12-18h, 18-24h.

[0059] More preferably, in the step b5), the calcination temperature is 300-600℃. The calcination temperature can be 300-350℃, 350-400℃, 400-450℃, 450-500℃, 500-550℃, 550-600℃.

[0060] More preferably, in the step b5), the calcination time is 2h-24h. The calcination time can be 2-4h, 4-8h, 8-10h, 10-12h, 12-18h, 18-24h.

[0061] Preferably, the preparation method of the CuZr-based catalyst comprises the following steps:

[0062] c1) dissolving the CuZr oxide and the soluble salt of the second metal oxide in water to obtain a solution E;

[0063] c2) dissolving a precipitant in water to obtain a solution F;

[0064] c3) simultaneously dropping the solution F and the solution E into a mother liquor for co-precipitation until no more precipitate is produced;

[0065] c4) after the co-precipitation, aging is performed to obtain a solution G;

[0066] c5) performing solid-liquid separation, washing, drying and calcination on the obtained solid product to obtain the CuZr-based catalyst.

[0067] More preferably, in the step c1), the molar concentration of the solution E is 0.1-5mol / L. The molar concentration of the solution E can be 0.1-0.5mol / L, 0.5-1mol / L, 1-2mol / L, 2-3mol / L, 3-4mol / L, 4-5mol / L.

[0068] More preferably, in the step c1), the soluble salt is selected from one or more of chloride, nitrate, sulfate, carbonate or acetate.

[0069] More preferably, in the step c2), the concentration of the solution E is 0.1-5mol / L. The molar concentration of the solution F can be 0.1-0.2mol / L, 0.2-1mol / L, 1-2mol / L, 2-3mol / L, 3-4mol / L, 4-5mol / L.

[0070] More preferably, in the step c2), the precipitant is selected from one or more of Na2CO3, K2CO3, (NH4)2CO3, NaOH, KOH and NH3H2O.

[0071] More preferably, in the step c3), the mother liquor is water.

[0072] More preferably, in the step c3), the temperature of the co-precipitation is 30-100°C. For example, the temperature of the co-precipitation can be 30-40°C, 40-50°C, 50-60°C, 60-70°C, 70-80°C, 80-100°C.

[0073] More preferably, in the step c3), the pH of the mother liquor during the co-precipitation is 7-12. For example, the pH of the mother liquor during the co-precipitation can be 7-7.5, 7.5-8.5, 8.5-9.5, 9.5-10, 10-11, 11-12.

[0074] Further, in the step c3), the solution E and the solution F are dropped into water in a co-current manner, and the dropping speed is controlled so that the pH of the mother liquor during the co-precipitation is maintained at 7-12.

[0075] More preferably, in the step c4), the temperature of the aging is 30-100°C. For example, the temperature of the aging can be 30-40°C, 40-50°C, 50-60°C, 60-70°C, 70-80°C, 80-100°C.

[0076] More preferably, in the step c4), the time of the aging is 2-48h. For example, the time of the aging can be 2-4h, 4-10h, 10-12h, 12-18h, 18-24h, 24-30h, 30-36h, 36-42h, 42-48h.

[0077] More preferably, in the step c5), the temperature of the drying is 100-150°C. For example, the temperature of the drying can be 100-110°C, 110-120°C, 120-130°C, 130-140°C, 140-150°C.

[0078] More preferably, in the step c5), the time of the drying is 6-24h. For example, the time of the drying can be 6-12h, 12-18h, 18-24h.

[0079] More preferably, in the step c5), the temperature of the calcination is 300-600°C. For example, the temperature of the calcination can be 300-350°C, 350-400°C, 400-450°C, 450-500°C, 500-550°C, 550-600°C.

[0080] More preferably, in step c5), the roasting time is 2h to 24h. For example, the roasting time can be 2h to 4h, 4h to 8h, 8h to 10h, 10h to 12h, 12h to 18h, or 18h to 24h.

[0081] The third aspect of this application discloses the use of the above-mentioned composite oxide catalyst in the preparation of ethanol by carbon dioxide hydrogenation. Before using the composite oxide catalyst in the preparation of ethanol by carbon dioxide hydrogenation, the catalyst is first subjected to reduction treatment and carbonization treatment in sequence.

[0082] More preferably, the gas used in the reduction process is selected from one or more of H2, CO, syngas, and inert gases.

[0083] More preferably, the temperature of the reduction treatment is 200–500°C. For example, the temperature of the reduction treatment can be 200–250°C, 250–300°C, 300–350°C, 350–400°C, 400–450°C, or 450–500°C.

[0084] More preferably, the reduction treatment time is 2 to 48 hours. For example, the reduction treatment time can be 2 to 4 hours, 4 to 10 hours, 10 to 12 hours, 12 to 18 hours, 18 to 24 hours, 24 to 30 hours, 30 to 36 hours, 36 to 42 hours, or 42 to 48 hours.

[0085] More preferably, the space velocity of the reduction treatment is 1000-30000 h⁻¹. -1 The space velocity for the reduction process described above can be 1000 h⁻¹. -1 ~2000h -1 2000h -1 ~6000h -1 6000h -1 ~8000h -1 8000h -1 ~10000h -1 10000h -1 ~20000h -1 20000h -1 ~30000h -1 .

[0086] More preferably, the gas used in the carbonization process is selected from one or more of CO, syngas, and inert gases.

[0087] More preferably, the space velocity for the carbonization process is 1000 to 30000 h⁻¹. For example, the space velocity for the carbonization process can be 1000 h⁻¹. -1 ~2000h -1, 2000h -1 , 6000h -1 , 6000h -1 , 8000h -1 , 8000h -1 , 10000h -1 , 10000h -1 , 20000h -1 , 20000h -1 , 30000h -1 .

[0088] More preferably, the temperature of the carbonization treatment is 200-400℃. For example, the temperature of the carbonization treatment can be 200-250℃, 250-300℃, 300-350℃, 350-400℃.

[0089] More preferably, the time of the carbonization treatment is 5-48h. For example, the time of the carbonization treatment can be 5-10h, 10-12h, 12-18h, 18-24h, 24-30h, 30-36h, 36-42h, 42-48h.

[0090] The fourth aspect of the present application discloses a method for preparing ethanol by using the composite oxide catalyst as described above, wherein carbon dioxide and hydrogen gas are reacted to prepare ethanol under the catalysis of the composite oxide catalyst.

[0091] Preferably, the volume ratio of H2 to CO2 is (0.5-5):1. For example, the volume ratio of H2 to CO2 in the gas can be (0.5-1):1, (1-2):1, (2-3):1, (3-4):1, (4-5):1.

[0092] More preferably, the volume ratio of H2 to CO2 is (2-5):1.

[0093] Preferably, the composite oxide catalyst is crushed into tablets and then loaded into a fixed bed reactor for reaction.

[0094] More preferably, the temperature of the reaction is 200-400℃. For example, the temperature of the reaction can be 200-260℃, 260-300℃, 300-350℃, 350-400℃.

[0095] More preferably, the space velocity of the reaction is 1000-20000h -1 . For example, the space velocity of the reaction can be 1000-2000h -1 , 2000-3000h -1 , 3000-6000h -1 , 3000-6000h -1, 6000 ~ 10000 h -1 , 10000 ~ 15000 h -1 , 15000 ~ 20000 h -1 .

[0096] More preferably, the pressure of the reaction is 2 ~ 10 MPa. For example, the pressure of the reaction can be 2 ~ 3 MPa, 3 ~ 4 MPa, 4 ~ 5 MPa, 5 ~ 6 MPa, 6 ~ 7 MPa, 7 ~ 8 MPa, 8 ~ 9 MPa, 9 ~ 10 MPa.

[0097] Compared with the prior art, the present application has the following beneficial effects:

[0098] (1) The Fe-based catalyst and CuZr-based catalyst in the composite oxide catalyst described in the present application synergistically act so that the catalyst exhibits high activity in the ethanol synthesis reaction, and also exhibits high ethanol selectivity under the condition of high conversion rate, so that a single ethanol product with high purity can be obtained, the cost of separation can be greatly reduced, and economic benefits can be improved.

[0099] (2) The composite oxide catalyst described in the present application has good preparation repeatability, the raw materials of the composite oxide catalyst described in the present application have low price, the preparation method is simple and easy to control, and the same quality and performance products can be easily prepared repeatedly, thereby meeting the needs of industrial large-scale stable production, and effectively avoiding the problem that the preparation method of the traditional catalyst is too complex, is not easy to reproduce, and thus the stability of the quality of the catalyst cannot be effectively controlled.

[0100] (3) The composite oxide catalyst described in the present application has good performance repeatability, and the composite oxide catalyst described in the present application can be continuously used for a long time to obtain the same good catalytic effect, thereby reducing the time and labor and material cost required for replacing the catalyst in the continuous large-scale production in industry. DETAILED DESCRIPTION

[0101] The embodiments of the present application are described below 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 description.

[0102] 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, but not for limiting the scope of protection of the present application. The test methods in the following examples are not specified, and are usually carried out according to the conventional conditions, or according to the conditions recommended by the manufacturers.

[0103] When the embodiments give numerical ranges, it is understood that, unless the present invention indicates otherwise, each numerical range's two endpoints, and any number between the two endpoints, can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by one of ordinary skill in the art. Except in the examples, or where otherwise explicitly indicated, 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 belongs. Unless otherwise specified, any method, device, material or apparatus similar or equivalent to those described herein can be used in the practice of the present invention.

[0104] The reaction results of the catalysts described in the embodiments of the present application are obtained by the following methods:

[0105] 1) The types and contents of various components contained in the products are analyzed using a gas chromatograph (Agilent 8860);

[0106] 2) The CO2 conversion rate is calculated according to the number of carbon atoms, and the calculation formula is as follows:

[0107]

[0108] wherein CO2 inlet and CO2 outlet respectively represent the number of moles of CO2 into / out of the reaction system.

[0109] 3) The carbon monoxide selectivity calculation formula is:

[0110]

[0111] wherein CO outle represents the number of moles of CO out of the reaction tube.

[0112] 4) The methanol, ethanol and C 3+ alcohol selectivity calculation formula (3) is shown, and the C 3+ alcohol is an alcohol with a number of carbon atoms greater than or equal to 3.

[0113]

[0114] wherein, S i refers to the selectivity of a certain type of alcohol product i (i = methanol, ethanol, propanol), N i refers to the molar amount of a certain type of alcohol product i, and n i refers to the number of carbons of a certain type of alcohol product i (for example, n = 1 for methanol, n = 2 for ethanol, n = 3 for propanol, and so on).

[0115] The content of each oxide in the Fe-based catalyst and the CuZr-based catalyst in the following examples of the present application is obtained by calculating the amount of each raw material component used in the preparation method according to the theoretical conversion, and each oxide in the present application is calculated in the form of the most stable oxide.

[0116] In the Fe-based catalyst, the Fe oxide is Fe3O4, and the other oxides can be Co3O4, MnO2, MgO, CuO, ZnO, ZrO2, In2O3, BaO, La2O3, CeO2, TiO2, and SiO2.

[0117] In the CuZr-based catalyst, the CuZr oxide is CuO and ZrO2, and the second metal oxide can be MnO2, MgO, ZnO, and Al2O3.

[0118] The preparation method of the composite oxide catalyst in the present application comprises the following steps:

[0119] a1) dispersing the first carrier, the Fe-based catalyst, and the CuZr-based catalyst in water or an organic solvent;

[0120] a2) removing the liquid in the solution A to obtain a solid mixture;

[0121] a3) drying and calcining the solid mixture to obtain the composite oxide catalyst.

[0122] For the two raw materials of the Fe-based catalyst and the CuZr-based catalyst used in the present application, as long as they meet the following requirements: the content of the Fe oxide is 15wt% to 75wt% based on the mass of the Fe-based catalyst, and the content of the other oxides is 25wt% to 85wt%; the content of the CuZr oxide is 20wt% to 85wt% based on the mass of the CuZr-based catalyst, and the content of the second metal oxide is 15wt% to 80wt%.

[0123] In the following specific examples, the present application provides six specific Fe-based catalysts and their preparation methods. The Fe-based catalysts include A1, A2, A3, A4, A5, and A6, and the preparation methods of A1, A2, A3, A4, A5, and A6 are as follows, respectively.

[0124] In one preparation method of the A1, the following steps are included: 0.1 mol Fe(NO3)3·9H2O, 0.2 mol Co(NO3)2·6H2O, 0.5 mol Mg(NO3)2·6H2O are mixed to form a salt solution with a concentration of 5 mol / L, NaOH and Na2CO3 are mixed in a ratio of 1:2 to form a precipitant solution with a concentration of 0.2 mol / L, 5 g TiO2 carrier is added to a beaker containing 200 mL deionized water, and heated to 100°C under stirring. The mixed salt solution and the precipitant aqueous solution are added dropwise into the beaker at 100°C in a parallel flow manner to perform a precipitation reaction until no more precipitate is produced, the pH is controlled at about 12, and after the addition is completed, the solution is aged at 100°C for 2 h, and then centrifuged, washed, and dried at 120°C. The solid product is calcined at 600°C for 5 h to obtain the Fe-based catalyst A1. In the calcined A1, the content of Fe oxide is 15.8 wt% based on the mass of the A1, and the content of other oxides is 84.2 wt%.

[0125] In one preparation method of the A2, the following steps are included: 0.5 mol Fe(NO3)3·9H2O, 0.1 mol Mn(NO3)2·4H2O, 0.1 mol Cu(NO3)2·3H2O are mixed to form a salt solution with a concentration of 0.5 mol / L, NH3·H2O is mixed to form a precipitant solution with a concentration of 5 mol / L, and the above solutions are heated to 30°C. The mixed salt solution and the precipitant aqueous solution are added dropwise into a beaker at 30°C in a parallel flow manner to perform a precipitation reaction until no more precipitate is produced, the pH is controlled at about 7.5, and after the addition is completed, the solution is aged at 30°C for 48 h, and then centrifuged, washed, and dried at 120°C. The solid product is calcined at 300°C for 24 h to obtain the Fe-based catalyst without alkali metal. 5 g of the calcined Fe-based catalyst without alkali metal is impregnated with an equal volume of KNO3 0.1 g to load the K salt, and then dried at 120°C for 24 h and calcined at 300°C for 24 h to obtain the Fe-based catalyst A2. In the calcined A2, the content of Fe oxide is 71 wt% based on the mass of the A2, and the content of other oxides is 29 wt%.

[0126] In one preparation method of the A3, the following steps are included: 0.2 mol Fe(N03)3-9H20, 0.2 mol Co(N03)2-6H20, 0.1 mol Zn(N03)3-6H20, 0.05 mol In(N03)3are mixed to form a salt solution with a concentration of 3 mol / L, KOH and K2CO3 are mixed to form a precipitant solution with a concentration of 3 mol / L at a ratio of 1:2, and the above solutions are heated to 60°C. The mixed salt solution and the precipitant aqueous solution are added dropwise into a beaker at 60°C in a parallel flow manner to perform a precipitation reaction until no precipitate is generated, the pH is controlled at about 9.5, and after the dropping is completed, the solution is aged at 60°C for 4 h, followed by centrifugation, washing, and drying at 120°C. The solid product is calcined at 500°C for 10 h to obtain the Fe-based catalyst A3. In the calcined A3, the content of Fe oxide is 37.6 wt% and the content of other oxides is 62.4 wt% based on the mass of the A3.

[0127] In one preparation method of the A4, the following steps are included: 0.2 mol Fe(N03)3-9H20, 0.1 mol Co(N03)2-6H20, 0.1 mol Zn(N03)3-6H20 are mixed to form a salt solution with a concentration of 1 mol / L, NaOH and Na2CO3 are mixed to form a precipitant solution with a concentration of 2 mol / L at a ratio of 1:2, and the above solutions are heated to 80°C. The mixed salt solution and the precipitant aqueous solution are added dropwise into a beaker at 80°C in a parallel flow manner to perform a precipitation reaction until no precipitate is generated, the pH is controlled at about 9.5, and after the dropping is completed, the solution is aged at 80°C for 2 h, followed by centrifugation, washing, and drying at 120°C. The solid product is calcined at 350°C for 5 h to obtain the Fe-based catalyst A4. In the calcined A4, the content of Fe oxide is 48.8 wt% and the content of other oxides is 51.2 wt% based on the mass of the A4.

[0128] In one method of preparing the A5, the following steps are included: 0.3 mol Fe(N03)3-9H20, 0.3 mol Co(N03)2-6H20, 0.1 mol Zr(N03)4-5H20 and 0.05 mol La(N03)3are compounded into a salt solution with a concentration of 3 mol / L, (NH4)2C03is compounded into a precipitant solution with a concentration of 5 mol / L, and the above solutions are heated to 60°C. 5 g of Si02carrier is added to a beaker containing 50 mL of deionized water and heated to 60°C under stirring. The above mixed salt solution and the precipitant aqueous solution are dropped into the beaker at 60°C in a parallel flow manner to carry out a precipitation reaction until no more precipitate is produced, the pH is controlled at about 10, and after the dropping is completed, the solution is aged at 60°C for 24 h, followed by centrifugation, washing, and drying at 120°C. The above solid product is calcined at 400°C for 8 h to obtain an Fe-based catalyst without alkali metal. 5 g of the Fe-based catalyst without alkali metal after calcination is impregnated with an equal volume of Na2C03, 0.1 g of Na salt is loaded in an equal volume, followed by drying at 120°C for 24 h and calcination at 400°C for 4 h to obtain the Fe-based catalyst A5. In the calcined A5, the content of Fe oxide is 30.5 wt% and the content of other oxides is 69.5 wt% based on the mass of the A5.

[0129] In one method of preparing the A6, the following steps are included: 0.5 mol Fe(N03)3-9H20, 0.1 mol Co(N03)2-6H20, 0.01 mol Ba(N03)2and 0.1 mol Ce(N03)3-6H20 are compounded into a salt solution with a concentration of 2 mol / L, NaOH and Na2C03are compounded into a precipitant solution with a concentration of 2 mol / L at a ratio of 1:2, and the above solutions are heated to 80°C. The above mixed salt solution and the precipitant aqueous solution are dropped into a beaker at 60°C in a parallel flow manner to carry out a precipitation reaction until no more precipitate is produced, the pH is controlled at about 8.5, and after the dropping is completed, the solution is aged at 80°C for 10 h, followed by centrifugation, washing, and drying at 120°C. The above solid product is calcined at 500°C for 8 h to obtain an Fe-based catalyst without alkali metal. 5 g of the Fe-based catalyst without alkali metal after calcination is impregnated with an equal volume of CsN03, 0.1 g of Cs salt is loaded in an equal volume, followed by drying at 120°C for 24 h and calcination at 400°C for 4 h to obtain the Fe-based catalyst A6. In the calcined A6, the content of Fe oxide is 59 wt% and the content of other oxides is 41 wt% based on the mass of the A6.

[0130] In the following examples, the present application provides four specific CuZr-based catalysts and their preparation methods. The CuZr-based catalysts include B1, B2, B3 and B4, and their preparation methods are as follows.

[0131] In one of the preparation methods of B1, the following steps are included: 2 mol Cu(NO3)2·3H2O, 0.1 mol Zr(NO3)4·5H2O, 0.5 mol Zn(NO3)2·6H2O are mixed to form a mixed solution with a total metal concentration of 0.5 mol / L, and KOH and K2CO3 are dissolved in a certain amount of deionized water to form an alkali solution with a concentration of 0.5 mol / L. The mother liquor is added in a beaker, the dropping temperature is adjusted to 30°C, and the dropping pH is controlled at 10. The two solutions are co-precipitated in the stirred mother liquor in a parallel flow manner until no more precipitate is produced. After the dropping is completed, the aging is carried out at 30°C for 48 h, and then the centrifugation and washing are performed. The catalyst is dried in an oven at 150°C for 36 h, and then transferred to a muffle furnace for programmed heating to 600°C for 2 h. After the calcination is completed, the catalyst B1 is obtained. The CuZr oxide content is 81 wt% and the second metal oxide content is 19 wt% based on the mass of the B1.

[0132] In one of the preparation methods of B2, the following steps are included: 0.1 mol Cu(NO3)3·3H2O, 0.007 mol Zr(NO3)4·5H2O, 0.4 mol Mn(NO3)2·4H2O are mixed to form a mixed solution with a total metal concentration of 5 mol / L, and (NH4)2CO3 is dissolved in a certain amount of deionized water to form an alkali solution with a concentration of 5 mol / L. The mother liquor is added in a beaker, the dropping temperature is adjusted to 65°C, and the dropping pH is controlled at 12. The two solutions are co-precipitated in the stirred mother liquor in a parallel flow manner until no more precipitate is produced. After the dropping is completed, the aging is carried out at 65°C for 15 h, and then the centrifugation and washing are performed. The catalyst is dried in an oven at 100°C for 12 h, and then transferred to a muffle furnace for programmed heating to 450°C for 4 h. After the calcination is completed, the catalyst B2 is obtained. The CuZr oxide content is 20.2 wt% and the second metal oxide content is 79.8 wt% based on the mass of the B2.

[0133] In one preparation method of the B3, the following steps are included: 0.6 mol Cu(NO3)3·3H2O, 0.06 mol Zr(NO3)4·5H2O, 0.3 mol Zn(NO3)2·6H2O, and 0.1 mol Al(NO3)3·9H2O are mixed to form a mixed solution with a total metal concentration of 2 mol / L, NaOH and Na2CO3 are dissolved in deionized water to form a solution with a concentration of 2 mol / L, the two solutions are added to a beaker containing deionized water, the pH is controlled at about 9 at 80°C until no more precipitate is produced, the obtained product is washed by filtration with deionized water, and the obtained product is dried at 100°C. Finally, the dried product is calcined in a muffle furnace at 550°C for 8 h to obtain the catalyst B3. The CuZr oxide content is 65.25 wt% and the second metal oxide content is 34.75 wt% based on the mass of the B3.

[0134] In one preparation method of the B4, the following steps are included: 0.6 mol CuCl2·2H2O, 0.1 mol Zr(NO3)4·5H2O, 0.2 mol Mg(NO3)2·6H2O, and 0.2 mol Al(NO3)3·9H2O are mixed to form a mixed solution with a total metal concentration of 1 mol / L, KOH and K2CO3 are dissolved in a certain amount of deionized water to form an alkali solution with a concentration of 1 mol / L. The mother liquor is added to a beaker, the temperature for dropwise addition is adjusted to 65°C, the pH for dropwise addition is controlled at about 10, and the two solutions are co-precipitated in the stirred mother liquor in a parallel flow manner until no more precipitate is produced. After the dropwise addition is completed, the product is aged at 65°C for 15 h, is washed by centrifugation, is dried in an oven at 100°C for 12 h, is then transferred to a muffle furnace, and is calcined at a programmed temperature of 300°C for 24 h. The catalyst B4 is obtained after the calcination. The CuZr oxide content is 67.9 wt% and the second metal oxide content is 32.1 wt% based on the mass of the B4.

[0135] In one specific embodiment, the composite oxide catalyst is crushed into tablets and is loaded into a fixed bed reactor for reaction.

[0136] It should be noted that the amount of the composite oxide catalyst can be adjusted according to the catalytically effective amount of the specific catalyst, the reaction conditions, the convenience and economy of actual operation, and the stability of long-term operation.

[0137] Example 1

[0138] This embodiment provides a composite oxide catalyst, the raw materials of which include an Fe-based catalyst, a CuZr-based catalyst, and a first support. Based on the total mass of the raw materials of the composite oxide catalyst, the content of the Fe-based catalyst is 75 wt%, the content of the CuZr-based catalyst is 24 wt%, and the content of the first support is 1 wt%. The Fe-based catalyst is Al; the CuZr-based catalyst is B1; and the first support is SiO2.

[0139] This embodiment also provides a method for preparing a composite oxide catalyst, the method comprising the following steps:

[0140] 1) Add 250 mL of ethanol to a beaker, add 0.1 g of gaseous SiO2 to the beaker while stirring continuously, stir thoroughly at room temperature for 30 min, add 7.5 g of Al, continue stirring for 30 min, and finally add 2.4 g of B1 and stir for 2 h to form solution A;

[0141] 2) The ethanol in solution A was removed by rotary evaporation at 80°C to obtain a solid mixture;

[0142] 3) The solid mixture was dried at 120°C for 12 h and then calcined at 250°C for 10 h to obtain the composite oxide catalyst.

[0143] This embodiment also provides the use of a composite oxide catalyst in the hydrogenation of carbon dioxide to produce ethanol.

[0144] The composite oxide catalyst described in this embodiment is pressed into tablets and crushed to 40-60 mesh. 1.0 g of the crushed composite oxide catalyst is mixed evenly with 3.0 g of quartz sand of the same mesh size and then loaded into a fixed-bed reactor for reduction and carbonization treatment. Pure H2 is used as the reducing gas, and the reduction space velocity is 30,000 h⁻¹. -1 The reduction temperature was 500℃, and the reduction time was 2 hours. After the reduction process was completed, the temperature was lowered to 200℃, and then the synthesis gas with an H2 / CO ratio of 1 was switched to a concentration of 30,000 h⁻¹. -1 Carbonization was carried out at a space velocity of 48 h. After carbonization, the temperature was lowered to 80 °C, and a reaction gas with an H2 / CO2 ratio of 3 was introduced to purge for 30 min. Then, the back pressure of the same reaction gas was increased to 8.0 MPa, the reaction temperature was adjusted to 260 °C, and the reaction space velocity was 2000 h⁻¹. -1 The reaction was initiated. After the reaction was completed, the types and contents of various components in the product were analyzed using gas chromatography (Agilent 8860), and the conversion rate and selectivity of the reaction were calculated accordingly. The specific results are shown in Table 1.

[0145] Example 2

[0146] The embodiment provides a composite oxide catalyst, raw materials of the composite oxide catalyst comprising an Fe-based catalyst, a CuZr-based catalyst and a first carrier. The content of the Fe-based catalyst is 40% by weight, the content of the CuZr-based catalyst is 55% by weight, and the content of the first carrier is 5% by weight, based on the total mass of the raw materials of the composite oxide catalyst. The Fe-based catalyst is A2; the CuZr-based catalyst is B2; and the first carrier is Al2O3.

[0147] The embodiment also provides a preparation method of the composite oxide catalyst, the preparation method comprising the following steps:

[0148] 1) 250 mL of methanol is added into a beaker, 0.5 g of fumed Al2O3 is added into the beaker under continuous stirring, after being fully stirred at room temperature for 30 min, 4.0 g of A2 is added, and stirring is continued for 30 min, and finally 5.5 g of B2 is added, and stirring is performed for 1 h to form a solution A;

[0149] 2) The methanol in the solution A is removed by rotary evaporation at 100 DEG C to obtain a solid mixture;

[0150] 3) The solid mixture is dried at 120 DEG C for 12 h, and then calcined at 400 DEG C for 5 h to obtain the composite oxide catalyst.

[0151] The composite oxide catalyst is pressed into a tablet and broken to 40-60 mesh, 1.0 g of the broken composite oxide catalyst is mixed with 3.0 g of quartz sand of the same mesh, and then the mixture is uniformly mixed and filled into a fixed bed reactor to perform reduction treatment and carbonization treatment. The reduction gas is a mixed gas of H2 and N2, the volume content of H2 in the mixed gas is 10%, the reduction space velocity is 2000 h-1, the reduction temperature is 300 DEG C, and the reduction time is 24 h. After the reduction process is completed, the temperature is increased to 320 DEG C, the mixed gas of CO and Ar with a volume ratio of 1:1 is switched in, the space velocity of carbonization is 3000 h-1, and the carbonization is performed for 24 h. After the carbonization is completed, the temperature is decreased to 100 DEG C, the reaction gas of H2 / CO2=3 is switched in for 30 min, then the same reaction gas is used for back pressure to 8.0 MPa, the reaction temperature is adjusted to 320 DEG C, the reaction space velocity is 20000 h-1, and the reaction is started. After the reaction is completed, the types and contents of various components contained in the product are analyzed by using a gas chromatograph (Agilent 8860), and the conversion rate and the selectivity of the reaction are calculated accordingly, and the specific results are shown in Table 1. -1 -1 -1

[0152] Example 3

[0153] ​​​The embodiment provides a composite oxide catalyst, raw materials of the composite oxide catalyst comprising an Fe-based catalyst, a CuZr-based catalyst and a first carrier. The content of the Fe-based catalyst is 48% by weight, the content of the CuZr-based catalyst is 49.9% by weight, and the content of the first carrier is 2.1% by weight, based on the total mass of the raw materials of the composite oxide catalyst. The Fe-based catalyst is A3; the CuZr-based catalyst is B3; and the first carrier is SiO2.

[0154] The embodiment also provides a preparation method of the composite oxide catalyst, the preparation method comprising the following steps:

[0155] 1) 0.6 g of liquid silica sol (SiO2 content: 35% by weight) is added into a beaker with 250 mL of ethanol under constant stirring, after being fully stirred at room temperature for 30 min, 4.8 g of A3 is added, and stirring is continued for 30 min, and finally 4.99 g of B3 is added, and stirring is continued for 2 h to form a solution A;

[0156] 2) ethanol in the solution A is removed by rotary evaporation at 80 DEG C to obtain a solid mixture;

[0157] 3) the solid mixture is dried at 120 DEG C for 12 h, and then calcined at 500 DEG C for 2 h to obtain the composite oxide catalyst.

[0158] The embodiment also provides a use of the composite oxide catalyst in preparation of ethanol by carbon dioxide hydrogenation.

[0159] The composite oxide catalyst is pressed into a tablet and broken into 40-60 mesh, 1.0 g of the broken composite oxide catalyst is taken, 3.0 g of quartz sand of the same mesh size is added, and the mixture is uniformly mixed and then loaded into a fixed bed reactor for reduction treatment and carbonization treatment. Pure H2 is used as the reduction gas, the reduction space velocity is 10000 h-1, the reduction temperature is 400 DEG C, and the reduction time is 6 h. After the reduction process is completed, the temperature is reduced to 320 DEG C, and then the mixed gas with a volume ratio of synthesis gas to Ar being 1:1 is switched in, the H2 / CO in the synthesis gas is 1, the carbonization is performed at a space velocity of 10000 h-1 for 48 h, the temperature is reduced to 100 DEG C, the reaction gas of H2 / CO2=3 is switched in for purging for 30 min, then the same reaction gas is used for back pressure to 6.0 MPa, the reaction temperature is adjusted to 320 DEG C, and the reaction space velocity is 6000 h-1, and the reaction is started. After the reaction is completed, the types and contents of various components contained in the product are analyzed by using a gas chromatograph (Agilent 8860), and the conversion rate and the selectivity of the reaction are calculated accordingly, and the specific results are shown in Table 1. -1 -1 -1

[0160] Embodiment 4 ​​​

[0161] The embodiment provides a composite oxide catalyst, raw materials of the composite oxide catalyst comprising an Fe-based catalyst, a CuZr-based catalyst and a first carrier. The content of the Fe-based catalyst is 67% by weight, the content of the CuZr-based catalyst is 30% by weight, and the content of the first carrier is 3% by weight, based on the total mass of the raw materials of the composite oxide catalyst. The Fe-based catalyst is A4; the CuZr-based catalyst is B4; and the first carrier is TiO2.

[0162] The embodiment also provides a preparation method of the composite oxide catalyst, the preparation method comprising the following steps:

[0163] 1) 250 mL of acetone is added into a beaker, 0.3 g of TiO2 aerosol is added into the beaker under continuous stirring, 6.7 g of A4 is added after the beaker is stirred sufficiently at room temperature for 30 min, the stirring is continued for 30 min, finally, 3.0 g of B4 is added, and the stirring is continued for 5 h to form a solution A;

[0164] 2) acetone in the solution A is removed by rotary evaporation at 80°C to obtain a solid mixture;

[0165] 3) the solid mixture is dried at 120°C for 12 h, and then calcined at 450°C for 4 h to obtain the composite oxide catalyst.

[0166] The composite oxide catalyst is pressed into a tablet and broken into 40-60 mesh, 1.0 g of the broken composite oxide catalyst is mixed with 3.0 g of quartz sand of the same mesh, and then the mixture is uniformly filled into a fixed bed reactor to perform reduction treatment and carbonization treatment. The reduction gas is a mixed gas of CO and N2, the volume content of CO in the mixed gas is 10%, the reduction space velocity is 20000h-1, the reduction temperature is 300°C, and the reduction time is 12 h. After the reduction process is completed, the mixed gas of synthesis gas and Ar with a volume ratio of 1:1 is switched in, the H2 / CO in the synthesis gas is 1, the carbonization is performed at a space velocity of 20000h-1 for 24 h, the temperature is reduced to 100°C, the reaction gas of H2 / CO2=1 is switched in for 30 min, then the same reaction gas is used to back pressure to 4.0 MPa, the reaction temperature is adjusted to 340°C, the reaction space velocity is 10000h-1, and the reaction is started. After the reaction is completed, the types and contents of various components contained in the product are analyzed by using a gas chromatograph (Agilent 8860), and the conversion rate and the selectivity of the reaction are calculated accordingly, and the specific results are shown in Table 1. -1 -1 -1

[0167] Embodiment 5

[0168] ​​​This embodiment provides a composite oxide catalyst, the raw materials of which include an Fe-based catalyst, a CuZr-based catalyst, and a first support. Based on the total mass of the raw materials for the composite oxide catalyst, the Fe-based catalyst content is 75 wt%, the CuZr-based catalyst content is 23.6 wt%, and the first support content is 1.4 wt%. The Fe-based catalyst is A5; the CuZr-based catalyst is B3; and the first support is SiO2.

[0169] This embodiment also provides a method for preparing a composite oxide catalyst, the method comprising the following steps:

[0170] 1) Add 250 mL of ethanol to a beaker, and add 0.4 g of liquid silica sol (SiO2 content 35 wt%) to the beaker while stirring continuously. After stirring thoroughly at room temperature for 30 min, add 7.5 g of A5 and continue stirring for 30 min. Finally, add 2.36 g of B3 and stir for 5 h to form solution A.

[0171] 2) The ethanol in solution A was removed by rotary evaporation at 80°C to obtain a solid mixture;

[0172] 3) The solid mixture was dried at 120°C for 12 h and then calcined at 350°C for 10 h to obtain the composite oxide catalyst.

[0173] The composite oxide catalyst described in this embodiment is pressed into tablets and crushed to 40-60 mesh. 1.0 g of the crushed composite oxide catalyst is mixed evenly with 3.0 g of quartz sand of the same mesh size and then loaded into a fixed-bed reactor for reduction and carbonization treatment. Pure H2 is used as the reducing gas, and the reduction space velocity is 8000 h⁻¹. -1 The reduction temperature is 400℃, and the reduction time is 5 hours. After the reduction process is complete, the system switches to syngas, where the H2 / CO ratio is 1, and the reaction proceeds at a rate of 8000 h⁻¹. -1 Carbonization was carried out at a space velocity of 1000 h⁻¹ for 24 h. After carbonization, the temperature was lowered to 220 °C, and a reaction gas with an H₂ / CO₂ ratio of 5 was introduced to purge for 30 min. Then, the back pressure of the same reaction gas was adjusted to 10.0 MPa, the reaction temperature was adjusted to 260 °C, and the reaction space velocity was 1000 h⁻¹. -1 The reaction was initiated. After the reaction was completed, the types and contents of various components in the product were analyzed using gas chromatography (Agilent 8860), and the conversion rate and selectivity of the reaction were calculated accordingly. The specific results are shown in Table 1.

[0174] Example 6

[0175] The embodiment provides a composite oxide catalyst, raw materials of the composite oxide catalyst comprising an Fe-based catalyst, a CuZr-based catalyst and a first carrier. The content of the Fe-based catalyst is 50% by weight, the content of the CuZr-based catalyst is 49% by weight, and the content of the first carrier is 1% by weight, based on the total mass of the raw materials of the composite oxide catalyst. The Fe-based catalyst is A6; the CuZr-based catalyst is B1; and the first carrier is SiO2.

[0176] The embodiment also provides a preparation method of the composite oxide catalyst, the preparation method comprising the following steps:

[0177] 1) 250 mL of water is added into a beaker, 0.1 g of fumed SiO2 is added into the beaker under continuous stirring, after being fully stirred at room temperature for 30 min, 5.0 g of A6 is added, and stirring is continued for 30 min, and finally 4.9 g of B2 is added, and stirring is continued for 5 h to form a solution A;

[0178] 2) water in the solution A is removed by rotary evaporation at 80 DEG C to obtain a solid mixture;

[0179] 3) the solid mixture is dried at 120 DEG C for 12 h, and then calcined at 400 DEG C for 5 h to obtain the composite oxide catalyst.

[0180] The composite oxide catalyst is pressed into a tablet and broken into 40-60 mesh, 1.0 g of the broken composite oxide catalyst is mixed with 3.0 g of quartz sand of the same mesh, and then the mixture is uniformly mixed and filled into a fixed bed reactor to perform reduction treatment and carbonization treatment. The reduction gas is a mixed gas of H2 and N2, the volume content of H2 in the mixed gas is 50%, the reduction space velocity is 6000 h-1, the reduction temperature is 350 DEG C, and the reduction time is 8 h. After the reduction process is completed, the temperature is adjusted to 280 DEG C, a mixed gas with a CO / Ar volume ratio of 1:9 is switched in, carbonization is performed at a space velocity of 6000 h-1 for 24 h, after the carbonization is completed, the temperature is adjusted to 280 DEG C, a reaction gas with H2 / CO2=3 is switched in for purging for 30 min, then the same reaction gas is used to back pressure to 5.0 MPa, and reaction is started at a space velocity of 6000 h-1. After the reaction is completed, the types and contents of various components contained in the product are analyzed by using a gas chromatograph (Agilent 8860), and the conversion rate and the selectivity of the reaction are calculated accordingly, and the specific results are shown in Table 1. -1 -1 -1

[0181] Example 7

[0182] ​​​The embodiment provides a composite oxide catalyst, raw materials of the composite oxide catalyst comprising an Fe-based catalyst, a CuZr-based catalyst and a first carrier. The content of the Fe-based catalyst is 35 wt%, the content of the CuZr-based catalyst is 62 wt%, and the content of the first carrier is 3 wt% based on the total mass of the raw materials of the composite oxide catalyst. The Fe-based catalyst is A4; the CuZr-based catalyst is B2; and the first carrier is TiO2.

[0183] The embodiment also provides a preparation method of the composite oxide catalyst, the preparation method comprising the following steps:

[0184] 1) 250 mL of water is added into a beaker, 0.3 g of fumed TiO2 is added into the beaker under continuous stirring, after being fully stirred at room temperature for 30 min, 3.5 g of A4 is added, and stirring is continued for 30 min, and finally, 6.2 g of B2 is added, and stirring is continued for 5 h to form a solution A;

[0185] 2) water in the solution A is removed by rotary evaporation at 80 DEG C to obtain a solid mixture;

[0186] 3) the solid mixture is dried at 120 DEG C for 12 h, and then calcined at 400 DEG C for 4 h to obtain the composite oxide catalyst.

[0187] The composite oxide catalyst is pressed into a tablet and broken to 40-60 mesh, 1.0 g of the broken composite oxide catalyst is mixed with 3.0 g of quartz sand of the same mesh, and then the mixture is uniformly mixed and filled into a fixed bed reactor to perform reduction treatment and carbonization treatment. The reduction gas is a mixed gas of H2 and N2, the volume content of H2 in the mixed gas is 50%, the reduction space velocity is 10000 h-1, the reduction temperature is 250 DEG C, and the reduction time is 32 h. After the reduction process is completed, the synthesis gas is switched to, the volume ratio of H2 to CO in the synthesis gas is 1, the carbonization space velocity is 10000 h-1, and the carbonization time is 48 h. After the carbonization is completed, the reaction gas with a volume ratio of H2 to CO2 of 2 is switched in for purging for 30 min, then the same reaction gas is used to back pressure to 6.0 MPa, the reaction temperature is adjusted to 320 DEG C, the reaction space velocity is 3000 h-1, and the reaction is started. After the reaction is completed, the types and contents of various components contained in the product are analyzed by using a gas chromatograph (Agilent 8860), and the conversion rate and the selectivity of the reaction are calculated accordingly, and the specific results are shown in Table 1. -1 -1 -1

[0188] Embodiment 8

[0189] ​​​The embodiment provides a composite oxide catalyst, raw materials of the composite oxide catalyst comprising an Fe-based catalyst, a CuZr-based catalyst and a first carrier. The content of the Fe-based catalyst is 55 wt%, the content of the CuZr-based catalyst is 41 wt%, and the content of the first carrier is 4 wt% based on the total mass of the raw materials of the composite oxide catalyst. The Fe-based catalyst is A4; the CuZr-based catalyst is B3; and the first carrier is SiO2.

[0190] The embodiment also provides a preparation method of the composite oxide catalyst, the preparation method comprising the following steps:

[0191] 1) 250 mL of water is added into a beaker, 0.4 g of fumed SiO2 is added into the beaker under continuous stirring, after being fully stirred at room temperature for 30 min, 5.5 g of A4 catalyst is added, and stirring is continued for 30 min, and finally, 4.1 g of B3 is added, and stirring is continued for 5 h to form a solution A;

[0192] 2) water in the solution A is removed by rotary evaporation at 80 DEG C to obtain a solid mixture;

[0193] 3) the solid mixture is dried at 120 DEG C for 12 h, and then calcined at 400 DEG C for 4 h to obtain the composite oxide catalyst.

[0194] The composite oxide catalyst is pressed into a tablet and broken to 40-60 mesh, 1.0 g of the broken composite oxide catalyst is mixed with 3.0 g of quartz sand of the same mesh, and then the mixture is uniformly mixed and filled into a fixed bed reactor to perform reduction treatment and carbonization treatment. The reduction gas is H2, the reduction space velocity is 8000 h-1, the reduction temperature is 350 DEG C, and the reduction time is 12 h. After the reduction process is completed, the synthesis gas is switched to, the synthesis gas is H2 / CO = 0.2, the carbonization space velocity is 8000 h-1, and the carbonization time is 48 h. After the carbonization is completed, the temperature is lowered to 280 DEG C, the reaction gas of H2 / CO2 = 3 is switched in for 30 min, then the same reaction gas is back-flushed to 8.0 MPa, the reaction temperature is adjusted to 300 DEG C, the reaction space velocity is 6000 h-1, and the reaction is started. After the reaction is completed, the types and contents of various components contained in the product are analyzed by using a gas chromatograph (Agilent 8860), and the conversion rate and the selectivity of the reaction are calculated accordingly, and the specific results are shown in Table 1. -1 -1 -1

[0195] Comparative Example 1

[0196] ​​​Catalyst A1 was tableted and crushed to 40-60 mesh. 1.0 g of the crushed catalyst A1 was mixed thoroughly with 3.0 g of quartz sand of the same mesh size and then loaded into a fixed-bed reactor for reduction and carbonization treatment. Pure H2 was used as the reducing gas, and the reduction space velocity was 10000 h⁻¹. -1 The reduction temperature was 400℃, and the reduction time was 2 hours. After the reduction process was completed, the temperature was lowered to 200℃, and then the synthesis gas with H2 / CO = 1 was switched to a concentration of 10,000 h⁻¹. -1 Carbonization was carried out at a space velocity of 48 h. After carbonization, the temperature was lowered to 80 °C, and a reaction gas with an H2 / CO2 ratio of 3 was introduced to purge for 30 min. Then, the back pressure of the same reaction gas was increased to 8.0 MPa, the reaction temperature was adjusted to 320 °C, and the reaction space velocity was 6000 h⁻¹. -1 The reaction was initiated. After the reaction was completed, the types and contents of various components in the product were analyzed using gas chromatography (Agilent 8860), and the conversion rate and selectivity of the reaction were calculated accordingly. The specific results are shown in Table 1.

[0197] Comparative Example 2

[0198] Catalyst B3 was compressed into tablets and crushed to 40-60 mesh. 1.0 g of the crushed catalyst B3 was mixed thoroughly with 3.0 g of quartz sand of the same mesh size and then loaded into a fixed-bed reactor for reduction and carbonization treatment. Pure H2 was used as the reducing gas, and the reduction space velocity was 10000 h⁻¹. -1 The reduction temperature was 400℃, and the reduction time was 2 hours. After the reduction process was completed, the temperature was lowered to 200℃, and then the synthesis gas with H2 / CO = 1 was switched to a concentration of 10,000 h⁻¹. -1 Carbonization was carried out at a space velocity of 48 h. After carbonization, the temperature was lowered to 80 °C, and a reaction gas with an H2 / CO2 ratio of 3 was introduced to purge for 30 min. Then, the back pressure of the same reaction gas was increased to 8.0 MPa, the reaction temperature was adjusted to 320 °C, and the reaction space velocity was 6000 h⁻¹. -1 The reaction was initiated. After the reaction was completed, the types and contents of various components in the product were analyzed using gas chromatography (Agilent 8860), and the conversion rate and selectivity of the reaction were calculated accordingly. The specific results are shown in Table 1.

[0199] Table 1. Catalytic reaction results of the examples.

[0200]

[0201] As shown in Table 1, the composite oxide catalyst described in this application exhibits high activity and high ethanol selectivity in the reaction of carbon dioxide hydrogenation to ethanol. Under certain synthesis conditions, the ethanol selectivity of the composite oxide catalyst described in the examples of this application exceeds 85%, which is far superior to the catalytic effects of the single Fe-based catalyst or the single CuZr-based catalyst in Comparative Examples 1 and 2.

[0202] In summary, the composite oxide catalyst of the present application has the characteristics of simple preparation, low cost, easy repetition and good stability; the composite oxide catalyst can be used for carbon dioxide hydrogenation to prepare ethanol and exhibits excellent catalytic performance; under the condition of higher single-pass CO2 conversion rate, higher ethanol selectivity is achieved, for example, when the single-pass CO2 conversion rate is 80.2%, the ethanol selectivity can reach 93.9%.

[0203] The present application effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0204] The above examples only illustrate the principles and effects of the present application, and are not used 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 completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A composite oxide catalyst characterized by comprising: The raw material of the composite oxide catalyst comprises a Fe-based catalyst, a CuZr-based catalyst and a first carrier; The content of the Fe-based catalyst is 20wt%-80wt% and the content of the CuZr-based catalyst is 15wt%-79wt% based on the total mass of the raw material of the composite oxide catalyst, and the content of the first carrier is 1wt%-5wt%; The Fe-based catalyst comprises Fe oxide and other oxides, the content of the Fe oxide is 15wt%-75wt% and the content of the other oxides is 25wt%-85wt% based on the mass of the Fe-based catalyst, and the other oxides comprise a first metal oxide, the first metal is selected from one or more of alkali metal, alkaline earth metal, transition metal, rare earth metal and Group IIIA metal; The CuZr-based catalyst comprises CuZr oxide and second metal oxide, the content of the CuZr oxide is 20wt%-85wt% and the content of the second metal oxide is 15wt%-80wt% based on the mass of the CuZr-based catalyst, and the second metal is selected from one or more of Zn, Al, Mg and Mn; The first carrier is selected from one or more of SiO2, TiO2 and Al2O3; The other oxides further comprise a second carrier, and the second carrier is selected from one or more of SiO2, TiO2 and Al2O3; The alkali metal is selected from one or more of Li, Na, K, Rb and Cs; The alkaline earth metal is selected from one or more of Mg, Ca and Ba; The transition metal is selected from one or more of Mn, Co, Zr, Cu and Zn; The rare earth metal is selected from one or both of La and Ce; The Group IIIA metal is selected from one or both of Al and In.

2. The composite oxide catalyst according to claim 1, characterized by The preparation method of the Fe-based catalyst comprises: b1) dissolving soluble salts of the Fe oxide and the first metal oxide except alkali metal in water to obtain solution B; b2) dissolving a precipitant in water to obtain solution C; b3) simultaneously dropping the solution B and the solution C into a mother liquor for co-precipitation until no more precipitate is produced; b4) after the co-precipitation, aging is performed to obtain solution D; b5) performing solid-liquid separation on the solution D, washing, drying and calcining the solid product obtained by the solid-liquid separation to obtain the Fe-based catalyst; And / or, the preparation method of the CuZr-based catalyst comprises the following steps: c1) dissolving soluble salts of the CuZr oxide and the second metal oxide in water to obtain solution E; c2) dissolving a precipitant in water to obtain solution F; c3) simultaneously dropping the solution F and the solution E into a mother liquor for co-precipitation until no more precipitate is produced; c4) after the co-precipitation, aging is performed to obtain solution G; c5) performing solid-liquid separation, washing, drying and calcining the solid product obtained by the solid-liquid separation to obtain the CuZr-based catalyst; And / or, the molar ratio of Cu to Zr in the CuZr oxide is (5-20):

1.

3. The composite oxide catalyst according to claim 2, characterized by In the step b3), the mother liquor also disperses the second carrier; And / or, in the step b1), the molar concentration of the solution B is 0.1-5 mol / L; And / or, in the step b2), the concentration of the solution C is 0.1-5 mol / L; And / or, in the step b2), the precipitant is selected from one or more of Na2CO3, K2CO3, (NH4)2CO3, NaOH, KOH and NH3·H2O; And / or, in the step b3), the temperature of the co-precipitation is 30-100℃; And / or, in the step b3), the mother liquor is water; And / or, in the step b3), the pH of the mother liquor in the co-precipitation process is 7-12; And / or, in the step b4), the temperature of the aging is 30-100℃; And / or, in the step b4), the time of the aging is 2-48h; And / or, in the step b5), the temperature of the calcination is 300-600℃; And / or, in the step b5), the time of the calcination is 2-24h. And / or, after the step b5), there is further impregnation, the solution of the impregnation is an aqueous solution of a soluble salt of the alkali metal, after the impregnation, the operation of the step b5) is repeated, and the concentration of the aqueous solution of the soluble salt of the alkali metal is 0.1-5 mol / L; And / or, in the step c1), the molar concentration of the solution E is 0.1-5 mol / L; And / or, in the step c2), the concentration of the solution F is 0.1-5 mol / L; And / or, in the step c2), the precipitant is selected from one or more of Na2CO3, K2CO3, (NH4)2CO3, NaOH, KOH and NH3·H2O; And / or, in the step c3), the mother liquor is water; And / or, in the step c3), the temperature of the co-precipitation is 30-100℃; And / or, in the step c3), the pH of the mother liquor in the co-precipitation process is 7-12; And / or, in the step c4), the temperature of the aging is 30-100℃; And / or, in the step c4), the time of the aging is 2-48h; And / or, in the step c5), the temperature of the calcination is 300-600℃; And / or, in the step c5), the time of the calcination is 2-24h.

4. The method for producing a composite oxide catalyst according to any one of claims 1 to 3, characterized by, The preparation method comprises the following steps: a1) mixing the first carrier, the Fe-based catalyst and the CuZr-based catalyst to obtain a solid mixture; a2) calcining the solid mixture to obtain the composite oxide catalyst.

5. The production method according to claim 4, characterized by, In the step a2), the temperature of the calcination is 200-500℃; and / or, in the step a2), the time of the calcination is 2-10h.

6. Use of the composite oxide catalyst according to any one of claims 1 to 3 for the production of ethanol by hydrogenation of carbon dioxide, characterized in that, Before the composite oxide catalyst is used for preparing ethanol by carbon dioxide hydrogenation, the catalyst is subjected to reduction treatment and carbonization treatment in sequence.

7. Use according to claim 6, characterized in that, The gas used in the reduction treatment is selected from one or more of H2, CO, synthesis gas and inert gas; and / or, the temperature of the reduction treatment is 200-500℃; and / or, the time of the reduction treatment is 2-48h; And / or, the space velocity of the reduction treatment is 1000 to 30000 h -1 ; and / or, the gas used in the carbonization treatment is selected from one or more of CO, synthesis gas and inert gas; And / or, the carbonization treatment has a space velocity of 1000 to 30000 h -1 ; and / or, the temperature of the carbonization treatment is 200-400℃; and / or, the time of the carbonization treatment is 5-48h.

8. A method for producing ethanol using the composite oxide catalyst according to any one of claims 1 to 3, characterized by, CO2 reacts with H2 under the catalysis of the composite oxide catalyst to produce ethanol.

9. The method of claim 8, wherein, The volume ratio of H2 to CO2 is (0.5-5):1; and / or, the temperature of the reaction is 200-400℃; and / or the space velocity of the reaction is 1000 to 20000 h -1 ; and / or, the pressure of the reaction is 3-10MPa.

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