Modified composite metal oxide catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a modified composite metal oxide catalyst and a preparation method and application thereof. The modified CuFe-based metal oxide has compact Cu-Fe interface sites, adsorption and activation of CO2 and H2 can be effectively promoted, and a low-carbon alcohol intermediate is formed through a CO * intermediate, so that CO byproduct selectivity is reduced; besides, the eight-membered ring pore structure of the MAlPO-34 molecular sieve is beneficial to inhibiting generation of C5 + long chain hydrocarbon, and the moderate acid strength of the MAlPO-34 molecular sieve can inhibit excessive hydrogenation of olefin while promoting conversion of an alcohol intermediate into low-carbon olefin. The catalyst provided by the invention can greatly improve the CO2 conversion rate and the true selectivity and yield of low-carbon olefins, and can also significantly reduce the formation of CO by-products.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and specifically relates to a modified composite metal oxide catalyst and a preparation method and application thereof. Background Art

[0002] CO 2 As raw materials, green hydrogen produced from renewable energy can be used to produce light olefins through catalytic hydrogenation. This method effectively reduces CO 2 Emissions, opening up a new path for the preparation of low-carbon olefins.

[0003] CO 2 Hydrogenation to produce low-carbon olefins is divided into the Fischer-Tropsch synthesis route and the methanol intermediate route. 2 The conversion rate is high, reaching more than 20%, but due to the limitation of Anderson-Schultz-Flory rule, the selectivity of light olefins is low, and it is difficult to exceed 58%, and the final yield of light olefins is less than 20%. The distribution of hydrocarbon products in the methanol intermediate route is not restricted by ASF rule, which significantly improves the selectivity of light olefins in hydrocarbon products to 70-80%, but CO 2 The conversion rate is low, generally only 5-20%, and a large amount of CO by-product will be generated. The selectivity of CO by-product can reach 40-80%, resulting in a significant decrease in the actual selectivity and yield of light olefins, which are lower than 60% and 16% respectively. Summary of the invention

[0004] The purpose of the present invention is to provide a modified composite metal oxide catalyst and a preparation method and application thereof. The modified composite metal oxide catalyst CO 2 The conversion rate is high, and the real selectivity and yield of light olefins are high.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a modified composite metal oxide catalyst, comprising a modified CuFe-based composite metal oxide and an acidic molecular sieve; the modified CuFe-based composite metal oxide is xY-Cu a Fe b O c , wherein Y is an alkali metal; the acidic molecular sieve is an acidic MAlPO-34 molecular sieve, wherein M is one or both of silicon and germanium.

[0007] Preferably, the mass ratio of the modified CuFe-based composite metal oxide to the acidic molecular sieve is 1:0.2-3.

[0008] Preferably, the xY-Cu a Feb O c The ratio of a to b is 1:1 to 50; the xY-Cu a Fe b O c The value of c is based on the total valence of the modified CuFe-based composite metal oxide being zero; and x is 0.1 to 5.0 wt%.

[0009] Preferably, when M in the acidic MAlPO-34 molecular sieve contains silicon, the molar ratio of Si to Al in the acidic MAlPO-34 molecular sieve is 0.01 to 0.25:1; when M in the acidic MAlPO-34 molecular sieve contains germanium, the molar ratio of Ge to Al in the acidic MAlPO-34 molecular sieve is 0.01 to 0.25:1.

[0010] Preferably, the method for preparing the acidic MAlPO-34 molecular sieve comprises the following steps: mixing an aluminum source, a phosphorus source, a template, an M source and water for a hydrothermal reaction.

[0011] Preferably, the particle size of the modified composite metal oxide catalyst is 10 to 80 meshes.

[0012] The present invention also provides a method for preparing the modified composite metal oxide catalyst described in the above scheme, comprising the following steps:

[0013] Mixing a water-soluble metal salt, water and an organic complexing agent for complexing reaction and then calcining, wherein the water-soluble metal salt includes a water-soluble copper salt, a water-soluble iron salt and a water-soluble alkali metal salt to obtain a modified CuFe-based composite metal oxide;

[0014] The modified CuFe-based composite metal oxide is mixed with the acidic MAlPO-34 molecular sieve to obtain the modified composite metal oxide catalyst.

[0015] Preferably, the calcination temperature is 300-650° C., the heat preservation calcination time is 5-12 hours, and the calcination atmosphere is air.

[0016] Preferably, the temperature of the complex reaction is 50-90° C., and the insulation reaction time is 5-15 hours; the complex reaction is carried out under stirring conditions.

[0017] The present invention also provides the use of the modified composite metal oxide catalyst described in the above scheme or the modified composite metal oxide catalyst obtained by the preparation method described in the above scheme in the preparation of light olefins by hydrogenation of carbon dioxide.

[0018] The present invention provides a modified composite metal oxide catalyst. The present invention uses a modified CuFe-based metal oxide and an acidic MAlPO-34 molecular sieve as a co-catalyst for CO 2Hydrogenation to produce low-carbon olefins can significantly increase CO 2 The modified CuFe-based metal oxide of the present invention has a compact Cu-Fe interface site, which can effectively promote the conversion of CO and the true selectivity and yield of low-carbon olefins in the total product. 2 and H 2 adsorption and activation, and the formation of low-carbon alcohol intermediates through CO* intermediates, thereby reducing the selectivity of CO by-products; in addition, the eight-membered ring pore structure of MAlPO-34 molecular sieve is conducive to suppressing C 5+ The production of long-chain hydrocarbons, and its moderate acid strength can promote the conversion of alcohol intermediates into light olefins while inhibiting the excessive hydrogenation of olefins. The results of the examples show that the modified composite metal oxide catalyst of the present invention is suitable for CO 2 When hydrogenating to produce light olefins, CO 2 The conversion rate is 75.1%, the actual selectivity and yield of light olefins in the total product are 48.7% and 36.6% respectively, the selectivity of CO by-product is only 3.3%, and the stability of the catalyst is more than 200h.

[0019] The present invention also provides a method for preparing the modified composite metal oxide catalyst described in the above scheme. The preparation method provided by the present invention has simple steps, low cost, no secondary pollution, and is suitable for large-scale industrial production.

[0020] The present invention also provides the modified composite metal oxide catalyst described in the above scheme or the modified composite metal oxide catalyst obtained by the preparation method described in the above scheme in CO 2 The modified composite metal oxide catalyst provided by the present invention can significantly improve the CO 2 The conversion rate, the true selectivity and yield of light olefins in the total product can also significantly reduce the formation of CO by-products, while improving the stability of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The XRD spectrum of the modified CuFe-based composite metal oxide prepared in Example 1;

[0023] Figure 2 TEM image of the modified CuFe-based composite metal oxide prepared in Example 1;

[0024] Figure 3 The modified composite metal oxide catalyst prepared in Example 1 was used for CO 2 Reaction performance diagram of hydrogenation to produce light olefins;

[0025] Figure 4 The modified composite metal oxide catalyst prepared in Example 1 was used for CO 2 Graph showing the true selectivity and yield of light olefins produced by hydrogenation. DETAILED DESCRIPTION

[0026] The present invention provides a modified composite metal oxide catalyst, comprising a modified CuFe-based composite metal oxide and an acidic molecular sieve; the modified CuFe-based composite metal oxide is xY-Cu a Fe b O c , wherein Y is an alkali metal; the acidic molecular sieve is an acidic MAlPO-34 molecular sieve, wherein M is one or both of silicon and germanium.

[0027] In the present invention, the mass ratio of the modified CuFe-based composite metal oxide to the acidic molecular sieve is preferably 1:0.2-3, specifically 1:0.25, 1:0.5, 1:1, 1:1.5, 1:2 or 1:2.5.

[0028] In the present invention, the modified CuFe-based composite metal oxide is xY-Cu a Fe b O c (a, b, c are the molar ratios of Cu, Fe, and O, respectively, x is the mass loading of the alkali metal, a, b, c, and x satisfy xY-Cu a Fe b O c The overall chemical valence state of xY-Cu a Fe b O c The ratio of a to b is preferably 1:1 to 50, specifically 1:4, 1:5, 1:15, 1:25, 1:30, 1:40 or 1:45; the xY-Cu a Fe b O c The value of c is based on the total valence of the modified CuFe-based composite metal oxide being zero; the x is preferably 0.1-5.0wt%, specifically 0.5wt%, 1.0wt%, 2.0wt%, 3.0wt%, 4.0wt% or 4.5wt%.

[0029] In the present invention, the alkali metal preferably includes one or more of Li, Na, K and Cs.

[0030] In the present invention, the acidic molecular sieve is an acidic MAlPO-34 molecular sieve; the preparation method of the acidic MAlPO-34 molecular sieve preferably comprises the following steps: mixing an aluminum source, a phosphorus source, a template, an M source and water for a hydrothermal reaction.

[0031] In the present invention, the aluminum source is preferably pseudo-boehmite; the phosphorus source is preferably phosphoric acid; the template is preferably tetraethylammonium hydroxide; the M source includes one or more of a silicon source and a germanium source; the silicon source is preferably tetraethyl orthosilicate; and the germanium source is preferably germanium oxide.

[0032] In the present invention, the molar ratio of the aluminum source to the phosphorus source is preferably 1:0.8 to 1.2, specifically 1:0.8, 1:0.9, 1:1 or 1:1.2.

[0033] In the present invention, the molar ratio of the aluminum source to the template is preferably 1:0.5-2, specifically 1:0.75, 1:1 or 1:2.

[0034] In the present invention, the molar ratio of the aluminum source to the M source is preferably 1:0.01 to 0.25, specifically 1:0.02, 1:0.03, 1:0.05, 1:0.1, 1:0.15 or 1:0.2.

[0035] In the present invention, the molar ratio of the aluminum source to water is preferably 1:25 to 60, specifically 1:25, 1:35, 1:45 or 1:60.

[0036] In the present invention, the temperature of the hydrothermal reaction is preferably 170-220°C, specifically 170°C, 180°C, 200°C or 220°C, and the insulation reaction time is preferably 15-40h, specifically 15h, 20h, 25h, 30h, 35h or 40h.

[0037] In the present invention, when the M source contains a silicon source, the molar ratio of Si to Al in the acidic MAlPO-34 molecular sieve is preferably 0.01 to 0.25:1, specifically 0.02:1, 0.03:1, 0.05:1, 0.1:1, 0.15:1 or 0.2:1.

[0038] In the present invention, when the M source contains a germanium source, the molar ratio of Ge to Al in the acidic MAlPO-34 molecular sieve is preferably 0.01 to 0.25:1, specifically 0.02:1, 0.03:1, 0.05:1, 0.1:1, 0.15:1 or 0.2:1.

[0039] In the present invention, when M in the acidic MAlPO-34 molecular sieve contains silicon, the molar ratio of Si to Al in the acidic MAlPO-34 molecular sieve is preferably 0.01 to 0.25:1, specifically 0.01:1, 0.05:1, 0.1:1, 0.15:1, 0.2:1 or 0.25:1; when M in the acidic MAlPO-34 molecular sieve contains germanium, the molar ratio of Ge to Al in the acidic MAlPO-34 molecular sieve is preferably 0.01 to 0.25:1, specifically 0.01:1, 0.05:1, 0.1:1, 0.15:1, 0.2:1 or 0.25:1.

[0040] In the present invention, the particle size of the modified composite metal oxide catalyst is preferably 10 to 80 meshes, specifically 20 meshes, 40 meshes or 60 meshes.

[0041] The modified composite metal oxide catalyst provided by the present invention is used for CO 2 Hydrogenation to produce low-carbon olefins can significantly increase CO 2 The conversion rate, the true selectivity and yield of light olefins in the total product can also be significantly reduced, and the formation of CO by-products can be improved, and the stability of the catalyst can be improved.

[0042] The present invention also provides a method for preparing the modified composite metal oxide catalyst described in the above scheme, comprising the following steps:

[0043] Mixing a water-soluble metal salt, water and an organic complexing agent for complexing reaction and then calcining, wherein the water-soluble metal salt includes a water-soluble copper salt, a water-soluble iron salt and a water-soluble alkali metal salt to obtain a modified CuFe-based composite metal oxide;

[0044] The modified CuFe-based composite metal oxide is mixed with the acidic MAlPO-34 molecular sieve to obtain the modified composite metal oxide catalyst.

[0045] The present invention mixes a water-soluble metal salt, water and an organic complexing agent (referred to as the first mixing) for complexing reaction and then calcines to obtain a modified CuFe-based composite metal oxide. In the present invention, the water-soluble copper salt preferably includes one or more of copper nitrate, copper chloride and copper sulfate, more preferably copper nitrate; the water-soluble iron salt preferably includes one or more of iron nitrate, iron chloride and iron sulfate, more preferably iron nitrate; the water-soluble alkali metal salt preferably includes one or more of alkali metal nitrate, alkali metal chloride and alkali metal sulfate, more preferably alkali metal nitrate.

[0046] In the present invention, the water is preferably deionized water.

[0047] In the present invention, the first mixing is preferably: mixing a water-soluble metal salt and water to obtain a composite metal salt solution, and mixing the composite metal salt solution and an organic complexing agent.

[0048] In the present invention, the concentration of copper ions in the composite metal salt solution is preferably 0.002-0.1 mol / L, specifically 0.0025 mol / L, 0.003 mol / L, 0.007 mol / L, 0.01 mol / L, 0.03 mol / L, 0.05 mol / L or 0.08 mol / L, the concentration of iron ions is preferably 0.05-0.5 mol / L, specifically 0.07 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L or 0.4 mol / L, and the concentration of alkali metals is preferably 0.005-0.02 mol / L, specifically 0.008 mol / L, 0.01 mol / L, 0.015 mol / L or 0.02 mol / L.

[0049] In the present invention, the organic complexing agent preferably includes one or more of glucose, citric acid, salicylic acid and tartaric acid, and more preferably glucose.

[0050] In the present invention, the molar ratio of all metal ions (copper ions, iron ions and alkali metal ions) in the composite metal salt solution to the organic complexing agent is preferably 1:1 to 4, specifically 1:2 or 1:3. The present invention can effectively promote the complexation of metal ions with the organic complexing agent to form a colloidal solid precursor by using the above-mentioned amount of organic complexing agent.

[0051] In the present invention, the temperature of the complex reaction is preferably 50-90°C, specifically 60°C or 80°C, and the insulation reaction time is preferably 5-15h, specifically 6h, 8h, 10h or 12h; the complex reaction is preferably carried out under stirring conditions; and the stirring is preferably magnetic stirring.

[0052] In the present invention, after the complexation reaction, the obtained colloidal solid precursor is preferably dried; the drying temperature is preferably 60 to 120°C, specifically 80°C or 100°C, the heat preservation and drying time is preferably 3 to 15h, specifically 4h, 7h, 10h or 12h; the drying equipment is preferably an oven. The present invention obtains a solid precursor by drying.

[0053] In the present invention, the calcination temperature is preferably 300-650°C, specifically 350°C, 450°C, 550°C or 600°C, the heat preservation calcination time is preferably 5-12h, specifically 6h, 8h or 10h; the calcination atmosphere is preferably air; the calcination equipment is preferably a muffle furnace.

[0054] After obtaining the modified CuFe-based composite metal oxide, the present invention mixes the modified CuFe-based composite metal oxide with an acidic MAlPO-34 molecular sieve (referred to as the second mixing) to obtain the modified composite metal oxide catalyst. In the present invention, the mass ratio of the modified CuFe-based composite metal oxide to the acidic MAlPO-34 molecular sieve is preferably 1:0.2 to 3.0, specifically 1:0.25, 1:0.5, 1:1.0, 1:1.5, 1:2.0 or 1:2.5.

[0055] In the present invention, the second mixing is preferably mechanical grinding mixing.

[0056] In the present invention, the second mixing preferably further comprises tableting, crushing and screening the obtained product in sequence.

[0057] The preparation method provided by the invention has simple steps, no secondary pollution and is suitable for industrial production.

[0058] The present invention also provides the use of the modified composite metal oxide catalyst described in the above scheme or the modified composite metal oxide catalyst obtained by the preparation method described in the above scheme in the preparation of light olefins by hydrogenation of carbon dioxide.

[0059] In the present invention, the use of the modified composite metal oxide catalyst in the preparation of light olefins by hydrogenation of carbon dioxide preferably comprises the following steps:

[0060] The modified composite metal oxide catalyst was reduced and then introduced with H 2 -CO 2 The mixed gas is subjected to hydrogenation reaction to obtain light olefins.

[0061] In the present invention, the reduction temperature is preferably 300-600°C, specifically 350°C, 420°C or 500°C, the insulation reduction time is preferably 1-6h, specifically 2h or 4h; the reduction atmosphere is preferably hydrogen.

[0062] In the present invention, the H 2 -CO 2 H in the mixed gas 2 and CO 2 The volume ratio of is preferably 1 to 8:1, specifically 2:1, 3:1, 4:1, 5:1, 6:1 or 7:1.

[0063] In the present invention, the H 2 -CO 2The space velocity of the mixed gas is preferably 1000 to 10000 mL / (h·g), specifically 2000 mL / (h·g), 3000 mL / (h·g), 5000 mL / (h·g), 6000 mL / (h·g) or 8000 mL / (h·g).

[0064] In the present invention, the temperature of the hydrogenation reaction is preferably 260-400°C, specifically 300°C, 320°C, 340°C, 360°C or 380°C; the pressure is preferably 0.5-6MPa, specifically 1MPa, 2MPa, 3MPa, 4MPa or 5MPa; the insulation reaction time is preferably 10-300h, specifically 15h, 20h, 50h, 80h, 120h, 160h, 200h or 250h.

[0065] In order to further illustrate the present invention, the scheme of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be understood as limiting the protection scope of the present invention.

[0066] Example 1

[0067] 7.42 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 2.13 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-copper-iron composite metal salt solution; 152.08 g of glucose was added to the sodium-copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-copper-iron composite oxide solid precursor; the sodium-copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 3% Na-Cu 0.15 Fe 1 O 1.71 Composite metal oxides.

[0068] The 3% Na-Cu 0.15 Fe 1 O 1.71 The composite metal oxide and the acidic GeAlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide catalyst with a particle size of 20 to 40 mesh was obtained by tableting, crushing and sieving.

[0069] Example 2

[0070] 7.19 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 0.50 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-copper-iron composite metal salt solution; 141.41 g of glucose was added to the sodium-copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-copper-iron composite oxide solid precursor; the sodium-copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 1% Na-Cu 0.15 Fe 1 O 1.67 Composite metal oxides.

[0071] The 1% Na-Cu 0.15 Fe 1 O 1.67 The composite metal oxide and the acidic GeAlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide catalyst with a particle size of 20 to 40 mesh was obtained by tableting, crushing and sieving.

[0072] Example 3

[0073] 73.85 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 1.48 g of potassium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium copper iron composite metal salt solution; 145.79 g of glucose was added to the potassium copper iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a potassium copper iron composite oxide solid precursor; the potassium copper iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain a 3% K-Cu composite oxide. 0.15 Fe 1 O 1.69 Composite metal oxides.

[0074] The 3% K-Cu 0.15 Fe 1 O 1.69 The composite metal oxide and the acidic GeAlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide catalyst with a particle size of 20 to 40 mesh was obtained by tableting, crushing and sieving.

[0075] Example 4

[0076] 24.33 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 1.24 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-copper-iron composite metal salt solution; 133.59 g of glucose was added to the sodium-copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-copper-iron composite oxide solid precursor; the sodium-copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 2% Na-Cu 0.05 Fe 1 O 1.58 Composite metal oxides.

[0077] The 2% Na-Cu 0.05 Fe 1 O 1.58 The composite metal oxide and the acidic GeAlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide catalyst with a particle size of 20 to 40 mesh was obtained by tableting, crushing and sieving.

[0078] Example 5

[0079] 9.41 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 1.41 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-copper-iron composite metal salt solution; 151.93 g of glucose was added to the sodium-copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-copper-iron composite oxide solid precursor; the sodium-copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 2% Na-Cu 0.19 Fe 1 O 1.74 Composite metal oxides.

[0080] The 2% Na-Cu 0.19 Fe 1 O 1.74 The composite metal oxide and the acidic GeAlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide catalyst with a particle size of 20 to 40 mesh was obtained by tableting, crushing and sieving.

[0081] Example 6

[0082] 7.42 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 2.13 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-copper-iron composite metal salt solution; 152.08 g of glucose was added to the sodium-copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-copper-iron composite oxide solid precursor; the sodium-copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 3% Na-Cu 0.15 Fe 1 O 1.71 Composite metal oxides.

[0083] The 3% Na-Cu 0.15 Fe 1 O 1.71 The composite metal oxide and the acidic GeAlPO-34 molecular sieve (Ge / Al molar ratio of 0.02) were mechanically ground, and the mass ratio of the two components after mixing was 1:1, followed by tableting, crushing and sieving to obtain a modified composite metal oxide catalyst with a particle size of 20 to 40 mesh.

[0084] Comparative Example 1

[0085] 80.80 g of ferric nitrate nine hydrate and 1.89 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-iron composite metal salt solution; 135.1 g of glucose was added to the sodium-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-iron composite oxide solid precursor; the sodium-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 3% Na-Fe 1 O 1.55 Composite metal oxides.

[0086] The 3% Na-Fe 1 O 1.55 The composite metal oxide and the acidic GeAlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide was tableted, crushed and sieved to obtain a sodium iron composite metal oxide catalyst with a particle size of 20 to 40 meshes.

[0087] Comparative Example 2

[0088] 7.08 g of copper nitrate trihydrate and 80.80 g of ferric nitrate nonahydrate were dissolved in 1500 mL of deionized water, and stirred to obtain a copper-iron composite metal salt solution; 136.3 g of glucose was added to the copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a copper-iron composite oxide solid precursor; the copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain Cu 0.15 Fe 1 O 1.65 Composite metal oxides.

[0089] The Cu 0.15 Fe 1 O 1.65 The composite metal oxide and the acidic GeAlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide was tableted, crushed and sieved to obtain a copper-iron composite oxide catalyst with a particle size of 20 to 40 mesh.

[0090] Comparative Example 3

[0091] 7.42 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 2.13 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-copper-iron composite metal salt solution; 152.08 g of glucose was added to the sodium-copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-copper-iron composite oxide solid precursor; the sodium-copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 3% Na-Cu 0.15 Fe 1 O 1.71 Composite metal oxides.

[0092] The 3% Na-Cu 0.15 Fe 1 O 1.71 The composite metal oxide and the acidic H-RUB-13 molecular sieve (Si / Al molar ratio is 200) are mechanically ground, and the mass ratio of the two components after mixing is 1:1. Subsequently, the composite metal oxide is tableted, crushed and sieved to obtain a modified copper-iron-based composite oxide catalyst with a particle size of 20 to 40 mesh.

[0093] Comparative Example 4

[0094] 7.42 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 2.13 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-copper-iron composite metal salt solution; 152.08 g of glucose was added to the sodium-copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-copper-iron composite oxide solid precursor; the sodium-copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 3% Na-Cu 0.15 Fe 1 O 1.71 Composite metal oxides.

[0095] The 3% Na-Cu 0.15 Fe 1 O 1.71 The composite metal oxide and the acidic H-ZSM-5 molecular sieve (Si / Al molar ratio is 60) are mechanically ground, and the mass ratio of the two components after mixing is 1:1, followed by tableting, crushing and sieving to obtain a modified copper-iron-based composite oxide catalyst with a particle size of 20 to 40 meshes.

[0096] Comparative Example 5

[0097] 7.42 g of copper nitrate trihydrate, 80.80 g of ferric nitrate nonahydrate and 2.13 g of sodium nitrate were dissolved in 1500 mL of deionized water, and stirred to obtain a sodium-copper-iron composite metal salt solution; 152.08 g of glucose was added to the sodium-copper-iron composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a sodium-copper-iron composite oxide solid precursor; the sodium-copper-iron composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain 3% Na-Cu 0.15 Fe 1 O 1.71 Composite metal oxides.

[0098] The 3% Na-Cu 0.15 Fe 1 O 1.71 The composite metal oxide and the acidic H-ZSM-11 molecular sieve (Si / Al molar ratio of 40) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide was tableted, crushed and sieved to obtain a modified copper-iron-based composite oxide catalyst with a particle size of 20 to 40 meshes.

[0099] Comparative Example 6

[0100] 29.75 g of zinc nitrate hexahydrate and 85.86 g of zirconium nitrate pentahydrate were dissolved in 1500 mL of deionized water, and stirred to obtain a zinc-zirconium composite metal salt solution; 178.35 g of glucose was added to the zinc-zirconium composite metal salt solution, and a complexation reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a zinc-zirconium composite oxide solid precursor; the zinc-zirconium composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain Zn 1 Zr 2 O 5 Composite metal oxides.

[0101] The Zn 1 Zr 2 O 5 The composite metal oxide and the acidic Ge-AlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide was tableted, crushed and sieved to obtain a zinc-zirconium composite oxide catalyst with a particle size of 20 to 40 mesh.

[0102] Comparative Example 7

[0103] 29.75 g of zinc nitrate hexahydrate and 80.02 g of chromium nitrate nonahydrate were dissolved in 1500 mL of deionized water, and stirred to obtain a zinc-chromium composite metal salt solution; 178.35 g of glucose was added to the zinc-chromium composite metal salt solution, and a complex reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain a zinc-chromium composite oxide solid precursor; the zinc-chromium composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain Zn 1 Cr 2 O 4 Composite metal oxides.

[0104] The Zn 1 Cr 2 O 4 The composite metal oxide and the acidic Ge-AlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide was tableted, crushed and sieved to obtain a zinc-chromium composite oxide catalyst with a particle size of 20 to 40 mesh.

[0105] Comparative Example 8

[0106] 31.88 g of indium nitrate nine hydrate and 85.86 g of zirconium nitrate pentahydrate were dissolved in 1500 mL of deionized water, and stirred to obtain an indium zirconium composite metal salt solution; 178.35 g of glucose was added to the indium zirconium composite metal salt solution, and a complexation reaction was carried out at 80° C. with magnetic stirring, and a colloidal solid precursor was obtained after the reaction for 6 hours; the colloidal solid precursor was dried in an oven at 100° C. for 12 hours to obtain an indium zirconium composite oxide solid precursor; the indium zirconium composite oxide solid precursor was transferred to a muffle furnace, and calcined in an air atmosphere at 500° C. for 6 hours to obtain In 1 Zr 2 O 5.5 Composite metal oxides.

[0107] In 1 Zr 2 O 5.5 The composite metal oxide and the acidic Ge-AlPO-34 molecular sieve (Ge / Al molar ratio of 0.07) were mechanically ground, and the mass ratio of the two components after mixing was 1:1. Subsequently, the composite metal oxide was tableted, crushed and sieved to obtain an indium zirconium composite oxide catalyst with a particle size of 20 to 40 meshes.

[0108] Application Examples 1 to 16

[0109] The catalysts prepared in Examples 1 to 6 and Comparative Examples 1 to 8 were reduced in a hydrogen atmosphere at 400°C for 2 h, and then subjected to CO 2 Performance testing of hydrogenation to produce light olefins.

[0110] The reaction conditions of the catalysts in Examples 1 to 6 (Application Examples 1 to 6) are: reaction temperature 320°C, reaction pressure 4 MPa, H 2 With CO 2 The volume ratio is 3:1, and the space velocity is 3000mL / (h·g).

[0111] The reaction conditions of the catalyst in Example 1 (Application Example 7) are: reaction temperature 320°C, reaction pressure 2.5 MPa, H 2 With CO 2 The volume ratio is 6:1 and the space velocity is 3000mL / (h·g).

[0112] The reaction conditions of the catalyst in Example 1 (Application Example 8) are: reaction temperature 320°C, reaction pressure 2.5 MPa, H 2 With CO 2 The volume ratio is 4:1 and the space velocity is 3000mL / (h·g).

[0113] The reaction conditions of the catalysts in Comparative Examples 1 to 5 (Application Examples 9 to 13) are: reaction temperature 320°C, reaction pressure 4 MPa, H 2 With CO2 The volume ratio is 3:1, and the space velocity is 3000mL / (h·g).

[0114] The reaction conditions of the catalysts in Comparative Examples 6 to 8 (Application Examples 14 to 16) are: reaction temperature 320°C, reaction pressure 2.5 MPa, H 2 With CO 2 The volume ratio is 4:1 and the space velocity is 3000mL / (h·g).

[0115] Application Examples 1 to 16 Catalyst CO 2 The catalytic reaction results of hydrogenation to prepare light olefins are shown in Tables 1 and 2.

[0116] Table 1 CO of Application Examples 1 to 16 2 Catalytic results of hydrogenation to produce light olefins

[0117]

[0118] Table 2 CO of Application Examples 1 to 16 2 True light olefin selectivity and yield during hydrogenation

[0119]

[0120]

[0121] Note: In Table 1, C 2 ＝ -C 4 ＝ , represents the selectivity of light olefins (ethylene, propylene and butene) in hydrocarbons, C 2 0 -C 4 0 Indicates the selectivity of low-carbon alkanes (ethane, propane and butane) in hydrocarbons; C 5+ It indicates the selectivity of long-chain hydrocarbons with carbon number exceeding 5 in hydrocarbons, and oxygen-containing compounds indicate the selectivity of methanol, dimethyl ether and low-carbon alcohols in hydrocarbons. In Table 2, the true selectivity of low-carbon olefins refers to the selectivity of low-carbon olefins in all products (including hydrocarbons and CO).

[0122] It can be seen from Table 1 and Table 2 that the modified composite metal oxide catalyst provided by the present invention has excellent CO 2 Catalytic performance of hydrogenation to produce light olefins, CO 2The conversion rate can reach 75.1%, the selectivity of low-carbon olefins in hydrocarbons is 50.4%, and the selectivity of CO byproducts is only 3.3%; more importantly, the real selectivity of low-carbon olefins in the total product reaches 48.7%, and the yield of low-carbon olefins is as high as 36.6%; compared with comparative example 1, when there is no copper, the real selectivity of low-carbon olefins drops to 47.9%; compared with comparative example 2, when there is no alkali metal, the real selectivity of low-carbon olefins is only 3.1%; compared with comparative examples 3 to 5, the use of H-RUB-13 molecular sieve with the same octahedral ring pore can obtain a higher selectivity for low-carbon olefins, but a large amount of oxygen-containing compounds are generated at the same time, indicating that the acidity of H-RUB-13 molecular sieve is weak, which is not conducive to the conversion of alcohol intermediates into low-carbon olefins; and the use of H-ZSM-5 or H-ZSM-11 molecular sieves with larger ten-membered ring pores will result in the generation of a large amount of C 5+ Compared with Comparative Examples 6 to 8, the conventional zinc-zirconium, zinc-chromium or indium-zirconium composite metal oxide-acidic molecular sieve catalyst can significantly improve the selectivity of low-carbon olefins in hydrocarbons, but CO 2 The conversion rate is low and a large amount of CO by-product is generated at the same time, resulting in the real selectivity and yield of light olefins in the total product being only 14.9% to 24.3% and 1.78% to 2.77%.

[0123] Test Example 1

[0124] The XRD spectrum of the modified CuFe-based composite metal oxide prepared in Example 1 was analyzed, and the results were as follows: Figure 1 shown.

[0125] according to Figure 1 It can be seen that the modified CuFe-based composite metal oxide prepared in Example 1 has good crystallinity and presents a typical diffraction peak of iron oxide, but no diffraction peak of copper oxide appears, indicating that the copper material is highly dispersed.

[0126] Test Example 2

[0127] The modified CuFe-based composite metal oxide prepared in Example 1 was subjected to TEM test, and the results are as follows: Figure 2 shown.

[0128] according to Figure 2 It can be seen that the prepared modified CuFe-based composite metal oxide presents a nanoparticle stacking morphology.

[0129] Test Example 3

[0130] The modified composite metal oxide catalyst prepared in Example 1 was used for CO 2 Hydrogenation to prepare low carbon olefins (Application Example 7) was tested for reaction performance, and the results were as follows Figure 3 shown.

[0131] according to Figure 3 It can be seen that the modified composite metal oxide catalyst prepared by the present invention exhibits excellent CO 2 Hydrogenation to produce light olefins performance, CO 2 The conversion rate is above 70%, the selectivity of light olefins in hydrocarbon products is close to 50%, and the selectivity of CO by-products does not exceed 5%.

[0132] Test Example 4

[0133] The modified composite metal oxide catalyst prepared in Example 1 was used for CO 2 The true selectivity and yield of light olefins prepared by hydrogenation (Application Example 7) were tested, and the results were as follows Figure 4 shown.

[0134] according to Figure 4 It can be seen that among the total products (including hydrocarbons, oxygen-containing compounds and CO), the selectivity of light olefins exceeds 48%, and the yield of light olefins is above 36%.

[0135] It can be seen from the above examples that the modified composite metal oxide catalyst provided by the present invention is used to catalyze CO 2 Hydrogenation to produce low-carbon olefins can significantly increase CO 2 The conversion rate, the true selectivity and yield of light olefins in the total product can also be significantly reduced, and the formation of CO by-products can be improved, and the stability of the catalyst can be improved.

[0136] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A modified composite metal oxide catalyst, characterized in that: The invention comprises a modified CuFe-based composite metal oxide and an acidic molecular sieve; the modified CuFe-based composite metal oxide is xY-Cu a Fe b O c , wherein Y is an alkali metal; the acidic molecular sieve is an acidic MAlPO-34 molecular sieve, wherein M is one or both of silicon and germanium.

2. The modified composite metal oxide catalyst according to claim 1, characterized in that The mass ratio of the modified CuFe-based composite metal oxide to the acidic molecular sieve is 1:0.2-3.

3. The modified composite metal oxide catalyst according to claim 1 or 2, characterized in that The xY-Cu a Fe b O c The ratio of a to b is 1:1 to 50; the xY-Cu a Fe b O c The value of c is based on the total valence of the modified CuFe-based composite metal oxide being zero; and x is 0.1 to 5.0 wt%.

4. The modified composite metal oxide catalyst according to claim 1, characterized in that When M in the acidic MAlPO-34 molecular sieve contains silicon, the molar ratio of Si to Al in the acidic MAlPO-34 molecular sieve is 0.01 to 0.25:1; when M in the acidic MAlPO-34 molecular sieve contains germanium, the molar ratio of Ge to Al in the acidic MAlPO-34 molecular sieve is 0.01 to 0.25:

1.

5. The modified composite metal oxide catalyst according to claim 1 or 4, characterized in that: The preparation method of the acidic MAlPO-34 molecular sieve comprises the following steps: mixing an aluminum source, a phosphorus source, a template, an M source and water to carry out a hydrothermal reaction.

6. The modified composite metal oxide catalyst according to claim 1, characterized in that The particle size of the modified composite metal oxide catalyst is 10 to 80 meshes.

7. The method for preparing the modified composite metal oxide catalyst according to any one of claims 1 to 6, characterized in that: The following steps are involved: Mixing a water-soluble metal salt, water and an organic complexing agent for complexing reaction and then calcining, wherein the water-soluble metal salt includes a water-soluble copper salt, a water-soluble iron salt and a water-soluble alkali metal salt to obtain a modified CuFe-based composite metal oxide; The modified CuFe-based composite metal oxide is mixed with the acidic MAlPO-34 molecular sieve to obtain the modified composite metal oxide catalyst.

8. The preparation method according to claim 7, characterized in that: The calcination temperature is 300-650° C., the heat preservation calcination time is 5-12 hours, and the calcination atmosphere is air.

9. The preparation method according to claim 7 or 8, characterized in that: The temperature of the complex reaction is 50-90° C., and the heat preservation reaction time is 5-15 hours; the complex reaction is carried out under stirring conditions.

10. Use of the modified composite metal oxide catalyst according to any one of claims 1 to 6 or the modified composite metal oxide catalyst obtained by the preparation method according to any one of claims 7 to 9 in the preparation of light olefins by hydrogenation of carbon dioxide.

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