Catalyst for synthesizing low-carbon olefin through CO2 hydrogenation reaction as well as preparation and application of catalyst

Abstract

The invention discloses a catalyst for synthesizing low-carbon olefin through CO2 hydrogenation reaction as well as preparation and application of the catalyst. The catalyst comprises an active component A and a core-shell structure B (at) C, wherein the active component A is a metal oxide with catalytic activity for synthesizing low-carbon olefin through a CO2 hydrogenation reaction; in the core-shell structure B (at) C, B is an SAPO molecular sieve, and C is selected from one or more of B2O3, SiO2, Al2O3, TiO2, ZrO2, kaolin and montmorillonite. The catalyst is used for synthesizing low-carbon olefin through CO2 hydrogenation, and can obviously improve the CO2 conversion efficiency and reduce the CO selectivity.

Description

Technical Field

[0001] The present invention relates to a catalyst for preparing light olefins, in particular to a CO 2 Catalysts for synthesizing light olefins by hydrogenation reaction and their preparation and application. Background Art

[0002] Light olefins are the most important basic chemical raw materials. Starting from light olefins (C2=-C4=, ethylene, propylene and butene), a variety of chemical raw materials and products can be prepared, affecting all aspects of people's daily life. Carbon dioxide hydrogenation to light olefins can be achieved through direct and indirect routes. The direct route is generally considered to be the reduction of carbon dioxide to carbon monoxide through the reverse water gas shift reaction (RWGS), and carbon monoxide is then hydrogenated to produce light olefins through the Fischer-Tropsch synthesis reaction; while the indirect route is usually carried out in several different reactors, and the intermediate products of the reaction include synthesis gas and / or methanol. Another direct route is to couple the indirect route, where carbon dioxide is hydrogenated on the surface of metal oxides to form reaction intermediates, and the reaction intermediates then diffuse into the molecular sieve channels for conversion to form olefins. However, due to the high thermodynamic stability of carbon dioxide molecules, it is very challenging to make catalysts efficiently catalyze the hydrogenation of carbon dioxide to produce olefins. Therefore, although there have been many studies on the hydrogenation of carbon dioxide to produce light olefins, the conversion efficiency is still not high enough. Tsubaki et al. (catal.commun.2019,130,105759) used a bimetallic Fe / Co catalyst and achieved an olefin selectivity of 70.9% at a carbon dioxide conversion rate of 25.9%, but the byproducts of carbon monoxide and methane were still relatively high. The InZrO / SAPO-34 bifunctional catalyst developed by Professor Sun Yuhan of the Institute of Advanced Studies of the Chinese Academy of Sciences (ACS Catal.2018,8,571-578) can achieve 35% CO 2 The conversion rate and C2-C4 olefin selectivity are around 80%, but the CO selectivity is still very high.

[0003] In summary, the coupled catalyst system can achieve CO 2 Gas hydrogenation is used to directly convert low-carbon olefins. However, due to the limitations of the catalyst system, CO 2 The conversion rate is low, the olefin selectivity is not high, especially the CO selectivity is high. Therefore, a new high-performance coupled catalyst system is constructed to achieve CO 2 Efficient conversion by hydrogenation has far-reaching significance. Summary of the invention

[0004] Based on the defects of the prior art that the coupled catalyst system has low reaction activity, low selectivity of the target product and high selectivity of the by-product, the present invention provides a CO 2Catalyst for synthesizing low-carbon olefins by hydrogenation reaction and its preparation and application. The catalyst of the present invention is used for CO 2 When hydrogenating to produce light olefins, the carbon dioxide conversion efficiency can be significantly improved and the carbon monoxide selectivity can be reduced while maintaining the olefin selectivity.

[0005] In a first aspect, the present invention provides a CO 2 A catalyst for synthesizing light olefins by hydrogenation reaction, the catalyst comprising an active component A and a core-shell structure B@C, wherein the active component A is a catalyst for CO 2 Metal oxides with catalytic activity for synthesizing light olefins by hydrogenation reaction; in the core-shell structure B@C, B is SAPO molecular sieve, and C is selected from B 2 O 3 、SiO 2 、Al 2 O 3 、TiO 2 、ZrO 2 , kaolin, and montmorillonite.

[0006] In the above technical solution, the metal oxide is selected from InCr b Al y O x 、InAl b O x 、InCe b Al y O x 、InZr b Al y O x 、InMn b Al y O x 、InMn b Zr y O x 、InCo b Al y O x 、InFe b Al y O x or InZr b O x -InAl b O x One or more of, wherein b = 1 / 3 to 3 / 1, y = 1 / 100 to 1 / 5; preferably, the metal oxide is selected from InCr b Al y O x 、InAl b O x 、InCe b Al y Ox or InZr b Al y O x One or more of the above, wherein b=1 / 3 to 3 / 1, y=1 / 100 to 1 / 5, preferably b=1 / 3 to 1 / 1, y=1 / 100 to 1 / 10.

[0007] In the above technical solution, the SAPO molecular sieve is selected from one or more of SAPO-14, SAPO-17, SAPO-18, SAPO-34, SAPO-35, SAPO-42, SAPO-44, SAPO-47, and SAPO-56.

[0008] In the above technical solution, preferably, C is selected from B 2 O 3 、SiO 2 、Al 2 O 3 One or more of .

[0009] In the above technical solution, in the core-shell structure B@C, the weight ratio of B to C is 1000:1 to 2:1, preferably 100:1 to 5:1, and more preferably 50:1 to 10:1.

[0010] In the above technical solution, in the core-shell structure B@C, the molar ratio of silicon to aluminum in B is SiO 2 / Al 2 O 3 It is 0.001 to 0.60, preferably 0.01 to 0.40, and more preferably 0.05 to 0.20.

[0011] In the above technical solution, in the catalyst, the mass ratio of the active component A to the core-shell structure B@C is 1:8 to 8:1, preferably 1:3 to 3:1.

[0012] The second aspect of the present invention provides a method for preparing the above catalyst, comprising the following steps:

[0013] (1) mixing a phosphorus source, an aluminum source, a silicon source, a template and water to obtain a SAPO molecular sieve synthesis mixed gel, adding seed crystals, and subjecting the mixture to a hydrothermal crystallization treatment to obtain a B molecular sieve raw powder;

[0014] (2) mixing the C precursor with the B molecular sieve raw powder, and optionally subjecting it to hydrothermal treatment to obtain a core-shell structure B@C;

[0015] (3) The active component A is mixed with the core-shell structure B@C to obtain the catalyst.

[0016] In the above technical scheme, in the step (1), the phosphorus source is selected from one or more of phosphoric acid, phosphorous acid, phosphates and phosphorus oxides; the silicon source is selected from one or more of silica sol, silica gel, silicate, water glass and tetraethyl orthosilicate; the aluminum source is selected from one or more of pseudoboehmite, boehmite, aluminum sol, aluminum isopropoxide, tert-butyl aluminum, aluminate and activated alumina; and the template is selected from one or more of tetraethylammonium hydroxide, triethylamine, diethylamine, N,N-diisopropylethylamine, morpholine, cyclohexylamine, n-propylamine, isopropylamine, di-n-propylamine, diisopropylamine, tripropylamine, n-butylamine or isobutylamine.

[0017] In the above technical solution, the molar ratio of the mixed gel in step (1) is SiO 2 :Al 2 O 3 :P 2 O 5 :Template agent:H 2 O is (0.001~0.40):1:(0.85~1.25):(1.5~3.0):(20~100), the silicon source is SiO 2 The aluminum source is Al 2 O 3 Phosphorus source is P 2 O 5 count.

[0018] In the above technical solution, the seed crystal in step (1) is a solid powder of the molecular sieve corresponding to the core or a pre-crystallization mother liquor, and the proportion of alumina in the seed crystal to the aluminum source in step (1) calculated as alumina is 1.0wt% to 20wt%.

[0019] In the above technical solution, the crystallization condition in step (1) is 120-210° C. and the time is 12-72 hours. Stir or let stand.

[0020] In the above technical solution, conventional post-treatment steps such as separation, washing, drying and calcination can be adopted after crystallization in step (1), wherein the separation, washing, drying and calcination processes can adopt conventional methods, such as separation can be carried out by centrifugal separation, washing can be carried out by washing with deionized water, and drying can be carried out in an oven. For example, the drying conditions are: drying at 20-120°C for 2-24 hours; the calcination conditions are calcination at 420-650°C for 1-6 hours.

[0021] In the above technical solution, in step (2), the weight ratio of the B molecular sieve to the C precursor in terms of oxide is 1000:1 to 2:1, preferably 100:1 to 5:1, and more preferably 50:1 to 10:1.

[0022] In the above technical solution, in step (2), the C precursor can be a soluble compound, such as SiO2 The precursor can be one or more of silica sol, sodium silicate solution, and tetraethyl silicate; Al 2 O 3 The precursor can be one or more of aluminum sol, aluminum isopropoxide, and aluminum tert-butoxide; ZrO 2 The precursor can be zirconium nitrate, B 2 O 3 The precursor can be boric acid, TiO 2 The precursor may be tetrabutyl titanate. In step (2), the preparation method of the core-shell structure B@C may adopt a conventional coating method, such as a surface deposition method, a sol coating method, and the like.

[0023] In the above technical solution, the hydrothermal treatment conditions in step (2) are: standing and crystallizing at 120-210° C. for 12-72 hours.

[0024] In the above technical scheme, after the hydrothermal treatment in step (2), cooling, separation and drying are performed to obtain the core-shell structure B@C. The separation and drying are conventional operations in the art, for example, separation can be performed by centrifugal separation. The drying conditions are: drying at 20 to 120°C for 2 to 24 hours.

[0025] In the above technical solution, the metal oxide of the active component A in step (3) can be prepared by conventional methods, such as metal oxide InAl b O x or InCr b Al y O x The precursor of the metal oxide is prepared by precipitation in solution, separated, dried and then calcined to obtain the metal oxide; the metal oxide InZr b O x -InAl b O x InZr was first prepared by precipitation in solution. b O x and InAl b O x , and then prepared by physical mixing method.

[0026] In the above technical solution, the mixing in step (3) is conventional physical mixing.

[0027] A third aspect of the present invention provides a CO 2 Method for preparing light olefins by hydrogenation, CO 2 / H 2 The mixed gas contacts with the catalyst provided above to react and obtain a product containing light olefins.

[0028] In the above technical solution, the catalyst needs to be reduced before the reaction, and the reducing gas is hydrogen. The reduction conditions are as follows: the pressure is normal pressure, the temperature is 350-450°C, and the time is 1-5 hours.

[0029] In the above technical scheme, the reaction conditions are as follows: reaction temperature 320-500°C, reaction pressure 0.5-8MPa, CO 2 / H 2 The volumetric air velocity of the mixed gas is 1000~9600h -1 , CO 2 With H 2 The volume ratio is 1.0 to 5.0.

[0030] The inventors have found through research that the use of a catalyst comprising active component A and core-shell structure B@C for the carbon dioxide hydrogenation reaction to produce light olefins can significantly improve the carbon dioxide conversion efficiency, maintain high olefin selectivity, and reduce carbon monoxide selectivity. The catalyst preparation method of the present invention is simple, the raw materials are cheap and easy to obtain, and the preparation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The SAPO-34@Al obtained in Example 1 2 O 3 XRD pattern of core-shell structure;

[0032] Figure 2 The SAPO-34@Al obtained in Example 1 2 O 3 SEM image of the core-shell structure. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below by way of examples, but the protection scope of the present invention is not limited by the examples. In the present invention, wt% refers to mass fraction.

[0034] In the present invention, the test conditions of XRD and SEM are as follows:

[0035] XRD test conditions: The molecular sieve crystal phase analysis was performed using a Rigaku-Ultima X-ray diffractometer from Japan. CuKα radiation, wavelength λ = 0.15432nm. The X-ray diffraction pattern scanning range was 2θ5-50°, and the scanning speed was 10° / min.

[0036] SEM test conditions: Japan Hitachi S4800 field emission scanning electron microscope was used for testing.

[0037] In the present invention, the components after the reaction are separated and quantitatively analyzed by gas chromatography, CO 2 The calculation formula for conversion and C2-C4 olefin selectivity is:

[0038] CO 2 Conversion rate = (CO in synthesis gas raw material 2 Content-CO in reaction products 2 Content) / CO in synthesis gas raw material 2 Content × 100%, by volume;

[0039] CO selectivity = CO converted to CO 2 Mole / CO 2 Total moles converted × 100%;

[0040] C2-C4 olefin selectivity = CO converted to C2-C4 olefins 2 Mole number / (CO 2 Total moles converted - CO converted to CO 2 moles) × 100%.

[0041] [Example 1]

[0042] (1) InZr b Al y O x The mixed oxides were prepared as follows:

[0043] Weigh a certain amount of zirconium nitrate, indium nitrate and aluminum nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Al at 5 / 2.5 / 0.2, and stir until completely dissolved; weigh a certain amount of (NH 4 ) 2 CO 3 The solid was dissolved in water to prepare a 0.1 mol / L solution. The two aqueous solutions were simultaneously added dropwise to a beaker for co-precipitation. After precipitation, the solution was filtered, washed, dried at 100°C overnight, and calcined at 500°C for 4 hours.

[0044] (2) SAPO-34 molecular sieve was prepared according to the following steps:

[0045] Phosphoric acid, pseudoboehmite, silica sol, and triethylamine (TEA) are phosphorus source, aluminum source, silicon source, and template agent, respectively. The molar ratio of SiO 2 :Al 2 O 3 :P 2 O 5 :TEA:H 2O=0.10:1:0.95:3:50, after stirring at room temperature (25°C) for 1 hour, SAPO-34 molecular sieve was added as seed crystal (the alumina content in the seed crystal was 10.0wt% of the aluminum source in the feed in terms of alumina), stirred evenly, and then allowed to stand at 170°C for 24 hours for crystallization. The obtained solid was washed with deionized water until neutral, and the solid was separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-34 molecular sieve (SiO 2 / Al 2 O 3 The molar ratio is 0.10) powder.

[0046] (3) B@C: SAPO-34@Al 2 O 3 The core-shell structure was prepared as follows:

[0047] 2.5g aluminum sol (Al 2 O 3 20wt%) was dispersed in 18.0g water and stirred to disperse evenly; 9.5g of active component B molecular sieve was added to the above mixture and stirred evenly; the mixture was allowed to stand for crystallization at 120°C for 24h, cooled, centrifuged and dried to obtain SAPO-34@Al 2 O 3 Core-shell structure, its XRD pattern is as follows Figure 1 As shown in the SEM image Figure 2 as shown in .

[0048] (4) Catalyst preparation and reaction:

[0049] SAPO-34@Al 2 O 3 Core-shell structure powder and metal oxide InZr b Al y O x The catalyst is formed by physically mixing the raw materials in a mass ratio of 1:1, tableting and crushing to 20-40 meshes. The catalyst composition is shown in Table 1.

[0050] The catalyst was evaluated in a fixed bed microreactor. The reactor was a stainless steel reactor lined with a quartz tube. The catalyst was first reduced with pure hydrogen at atmospheric pressure and 400°C for 2 hours in the reactor, and then switched to a mixture of carbon dioxide and hydrogen (CO 2 :H 2 =1:1), at 400℃, 3.0MPa, 2000h -1 The reaction was carried out for 20 hours under the condition of space velocity, and the reaction product was monitored online by gas chromatography. The reaction results are shown in Table 2.

[0051] [Example 2]

[0052] (1) InZr b Al y O x The mixed oxides were prepared as follows:

[0053] Weigh a certain amount of zirconium nitrate, indium nitrate and aluminum nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Al at 4 / 3 / 0.2, and stir until completely dissolved; weigh a certain amount of (NH 4 ) 2 CO 3 The solid was dissolved in water to prepare a 0.1 mol / L solution. The two aqueous solutions were simultaneously added dropwise to a beaker for co-precipitation. After precipitation, the solution was filtered, washed, dried at 100°C overnight, and calcined at 500°C for 4 hours.

[0054] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0055] (3) B@C: SAPO-34@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0056] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0057] [Example 3]

[0058] (1) InZr b Al y O x The mixed oxides were prepared as follows:

[0059] Weigh a certain amount of zirconium nitrate, indium nitrate and aluminum nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Al at 1.5 / 3.5 / 0.1, and stir until completely dissolved; weigh a certain amount of (NH 4 ) 2 CO 3 The solid was dissolved in water to prepare a 0.1 mol / L mol / L solution. The two aqueous solutions were simultaneously added dropwise to a beaker for co-precipitation. After precipitation, the solution was filtered, washed, dried at 100°C overnight, and calcined at 500°C for 4 hours.

[0060] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0061] (3) B@C: SAPO-34@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0062] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0063] [Example 4]

[0064] (1) InZr b Al y O x The mixed oxides were prepared as follows:

[0065] Weigh a certain amount of zirconium nitrate, indium nitrate and aluminum nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Al at 2 / 4 / 0.2, and stir until completely dissolved; weigh a certain amount of (NH 4 ) 2 CO 3 The solid was dissolved in water to prepare a 0.1 mol / L solution. The two aqueous solutions were simultaneously added dropwise to a beaker for co-precipitation. After precipitation, the solution was filtered, washed, dried at 100°C overnight, and calcined at 500°C for 4 hours.

[0066] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0067] (3) B@C: SAPO-34@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0068] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0069] [Example 5]

[0070] (1) InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0071] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0072] (3) B@C: SAPO-34@SiO 2 The molecular sieves were prepared as follows:

[0073] 1.25 g silica sol (SiO 2 40% HAc content) was dispersed in 20g water and stirred to disperse evenly; 9.5g active component B molecular sieve was added to the above solution and stirred to mix evenly; a small amount of dilute acetic acid solution (HAc content 5%) was added to adjust the pH value of the mixed solution to 5-7; the mixed solution was allowed to stand at 120°C for crystallization for 24h, cooled, centrifuged and dried to obtain SAPO-34@SiO 2 Core-shell structure.

[0074] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0075] [Example 6]

[0076] (1) InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0077] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0078] (3) B@C: SAPO-34@B 2 O 3 The core-shell structure was prepared as follows:

[0079] 0.9 g of boric acid (H 3 BO 3 ) was dispersed in 20 g of water and stirred to disperse evenly; 9.5 g of active component SAPO-34 molecular sieve was added to the above solution and stirred to mix evenly; a small amount of dilute ammonia solution (NH 3 The mixture was placed at 120°C for crystallization for 24 hours, and then directly dried after cooling to obtain SAPO-34@B. 2 O 3 Core-shell structure.

[0080] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0081] [Example 7]

[0082] (1) InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0083] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0084] (3) B@C: SAPO-34@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0085] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0086] [Example 8]

[0087] (1) InZr b Al y Ox The mixed oxide was prepared according to [Example 2].

[0088] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0089] (3) B@C: SAPO-34@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0090] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0091] [Example 9]

[0092] (1) InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0093] (2) SAPO-18 molecular sieve is prepared according to the following process:

[0094] Phosphoric acid, aluminum isopropoxide, silica sol, and tetraethylammonium hydroxide (TEAOH) are phosphorus source, aluminum source, silicon source, and template agent, respectively. The molar ratio of SiO 2 :Al 2 O 3 :P 2 O 5 :TEA:H 2 O=0.10:1:2.0:4.0:50, stir at room temperature for 1 hour, then add SAPO-18 molecular sieve as seed (the alumina in the seed accounts for 10.0wt% of the aluminum source in the feed in terms of alumina), stir evenly, stand at 170°C for crystallization for 24h, wash the obtained solid with deionized water until neutral, separate the solid, dry, and calcine in a muffle furnace at 550°C for 6 hours to obtain SAPO-18 molecular sieve (SiO 2 / Al 2 O 3 The molar ratio is 0.10) powder.

[0095] (3) B@C: SAPO-18@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0096] 2.5g aluminum sol (Al 2 O 3 20wt%) was dispersed in 18.0g water and stirred to disperse evenly; 9.5g of active component B molecular sieve was added to the above mixed solution and stirred evenly; the mixed solution was allowed to stand for crystallization at 120°C for 24h, cooled, centrifuged and dried to obtain SAPO-18@Al2 O 3 Core-shell structure.

[0097] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0098] [Example 10]

[0099] (1) InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0100] (2) SAPO-17 molecular sieve is prepared according to the following process:

[0101] Phosphoric acid, aluminum isopropoxide, silica sol, and cyclohexylamine (CHA) are phosphorus source, aluminum source, silicon source, and template agent, respectively. The molar ratio of SiO 2 :Al 2 O 3 :P 2 O 5 :CHA:H 2 O=0.10:1:0.95.0:1.2:50, after stirring at room temperature for 1 hour, SAPO-17 molecular sieve was added as seed (the alumina content in the seed accounted for 10.0wt% of the total alumina in the feed), stirred evenly and then allowed to stand at 170°C for 24 hours for crystallization, the obtained solid was washed with deionized water until neutral, the solid was separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-17 molecular sieve (SiO 2 / Al 2 O 3 The molar ratio is 0.10) powder.

[0102] (3) B@C: SAPO-17@@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0103] 2.5g aluminum sol (Al 2 O 3 20wt%) was dispersed in 18.0g water and stirred to disperse evenly; 9.5g of active component B molecular sieve was added to the above mixture and stirred evenly; the mixture was allowed to stand for crystallization at 120°C for 24h, cooled, centrifuged and dried to obtain SAPO-17@Al 2 O 3 Core-shell structure.

[0104] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0105] [Example 11]

[0106] (1) InCr b Al y O x The mixed oxides were prepared as follows:

[0107] Weigh a certain amount of chromium nitrate, indium nitrate and aluminum nitrate solids and disperse them in water, keeping the molar ratio of In / Cr / Al at 4 / 3 / 0.2, and stir until completely dissolved; weigh a certain amount of (NH 4 ) 2 CO 3 The solid was dissolved in water to prepare a 0.1 mol / L solution. The two aqueous solutions were simultaneously added dropwise to a beaker for co-precipitation. After precipitation, the solution was filtered, washed, dried at 100°C overnight, and calcined at 500°C for 4 hours.

[0108] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0109] (3) B@C: SAPO-34@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0110] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0111] [Example 12]

[0112] (1)InCe b Al y O x The mixed oxides were prepared as follows:

[0113] Weigh a certain amount of cerium nitrate, indium nitrate and aluminum nitrate solids and disperse them in water, keeping the molar ratio of In / Ce / Al at 4 / 3 / 0.2, and stir until completely dissolved; weigh a certain amount of (NH 4 ) 2 CO 3 The solid was dissolved in water to prepare a 0.1 mol / L solution. The two aqueous solutions were simultaneously added dropwise to a beaker for co-precipitation. After precipitation, the solution was filtered, washed, dried at 100°C overnight, and calcined at 500°C for 4 hours.

[0114] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0115] (3) B@C: SAPO-34@Al 2 O 3 The core-shell structure was prepared according to [Example 1].

[0116] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0117] [Example 13]

[0118] (1) InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0119] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0120] (3) B@C: SAPO-34@TiO 2 The core-shell structure was prepared as follows:

[0121] 2.1 g of tetrabutyl titanate was dispersed in 20.0 g of tetrabutylammonium hydroxide solution, and the mixture was allowed to stand at 120 °C for 24 h for crystallization. 9.5 g of active component B molecular sieve was added to the crystallized mixture and stirred evenly. After cooling and centrifugation, SAPO-34@TiO 2 Core-shell structure.

[0122] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0123] [Comparative Example 1]

[0124] (1) InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0125] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0126] (3) Catalyst preparation and reaction:

[0127] SAPO-34 molecular sieve powder and metal oxide InZr b Al y O x The catalyst is formed by physically mixing the raw materials in a mass ratio of 1:1, tableting and crushing to 20-40 meshes. The catalyst composition is shown in Table 1.

[0128] The catalyst was evaluated in a fixed bed microreactor. The reactor was a stainless steel reactor lined with a quartz tube. The catalyst was first reduced with pure hydrogen at atmospheric pressure and 400°C for 2 hours in the reactor, and then switched to a mixture of carbon dioxide and hydrogen (CO 2 :H 2 =1:1), at 400℃, 3.0MPa, 2000h-1 The reaction was carried out for 20 hours under the condition of space velocity, and the reaction product was monitored online by gas chromatography. The reaction results are shown in Table 2.

[0129] [Comparative Example 2]

[0130] (1) InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0131] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0132] (3) B / C mixture: SAPO-34 / Al 2 O 3 The mixed oxides were prepared as follows:

[0133] 0.5g Al 2 O 3 The solid powder and 9.5 g SAPO-34 molecular sieve were placed in a ball mill and ground for 5 min. The resulting solid mixture was named SAPO-34 / Al 2 O 3 .

[0134] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 1. The reaction results are shown in Table 2.

[0135] [Comparative Example 3]

[0136] (1) Active component A: InZr b Al y O x The mixed oxide was prepared according to [Example 2].

[0137] (2) Catalyst preparation and reaction:

[0138] Alumina powder and metal oxide InZr b Al y O x The catalyst is formed by physically mixing the mixture in a mass ratio of 1:1, tableting and crushing the mixture into 20-40 meshes. The catalyst composition is shown in Table 1.

[0139] The catalyst was evaluated in a fixed bed microreactor. The reactor was a stainless steel reactor lined with a quartz tube. The catalyst was first reduced with pure hydrogen at atmospheric pressure and 400°C for 2 hours in the reactor, and then switched to a mixture of carbon dioxide and hydrogen (CO 2 :H 2 =1:1), at 400℃, 3.0MPa, 2000h -1The reaction was carried out for 20 hours under the condition of space velocity, and the reaction product was monitored online by gas chromatography. The reaction results are shown in Table 2.

[0140] Table 1

[0141]

[0142] Table 2

[0143]

[0144]

[0145] The above describes the specific implementation of the present invention in detail, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the various technical features being combined in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A catalyst for synthesizing light olefins by hydrogenation reaction of CO2, the catalyst comprising an active component A and a core-shell structure B@C, the active component A being a metal oxide having catalytic activity for synthesizing light olefins by hydrogenation reaction of CO2; in the core-shell structure B@C, B is a SAPO molecular sieve, and C is selected from one or more of B2O3, SiO2, Al2O3, TiO2, ZrO2, kaolin, and montmorillonite.

2. The catalyst according to claim 1, characterized in that The metal oxide is selected from InCr b Al y O x 、InAl b O x 、InCe b Al y O x 、InZr b Al y O x 、InMn b Al y O x 、InMn b Zr y O x 、InCo b Al y O x 、InFe b Al y O x or InZr b O x -InAl b O x One or more of, wherein b=1 / 3 to 3 / 1, y=1 / 100 to 1 / 5; Preferably, the metal oxide is selected from InCr b Al y O x 、InAl b O x 、InCe b Al y O x or InZr b Al y O x One or more of, wherein b=1 / 3 to 3 / 1, y=1 / 100 to 1 / 5, preferably b=1 / 3 to 1 / 1, y=1 / 100 to 1 / 10; And / or, C is selected from one or more of B2O3, SiO2, and Al2O3.

3. The catalyst according to claim 1, characterized in that The SAPO molecules are selected from one or more of SAPO-14, SAPO-17, SAPO-18, SAPO-34, SAPO-35, SAPO-42, SAPO-44, SAPO-47, and SAPO-56.

4. The catalyst according to claim 1, characterized in that In the core-shell structure B@C, the weight ratio of B to C is 1000:1 to 2:1, preferably 100:1 to 5:1, and more preferably 50:1 to 10:1; And / or, in the core-shell structure B@C, the silicon-aluminum molar ratio SiO2 / Al2O3 of B is 0.001 to 0.60, preferably 0.01 to 0.40, more preferably 0.05 to 0.20; And / or, in the catalyst, the mass ratio of active component A to core-shell structure B@C is 1:8 to 8:1, preferably 1:3 to 3:

1.

5. A method for preparing a catalyst according to any one of claims 1 to 4, comprising the following steps: (1) mixing a phosphorus source, an aluminum source, a silicon source, a template and water to obtain a SAPO molecular sieve synthesis mixed gel, adding seed crystals, and subjecting the mixture to a hydrothermal crystallization treatment to obtain a B molecular sieve raw powder; (2) mixing the C precursor with the B molecular sieve raw powder, and optionally subjecting it to hydrothermal treatment to obtain a core-shell structure B@C; (3) The active component A is mixed with the core-shell structure B@C to obtain the catalyst.

6. The catalyst according to claim 5, characterized in that In step (1), the phosphorus source is selected from one or more of phosphoric acid, phosphorous acid, phosphates and phosphorus oxides; the silicon source is selected from one or more of silica sol, silica gel, silicate, water glass and tetraethyl orthosilicate; the aluminum source is selected from one or more of pseudoboehmite, boehmite, aluminum sol, aluminum isopropoxide, tert-butyl aluminum, aluminate and activated alumina; the template is selected from one or more of tetraethylammonium hydroxide, triethylamine, diethylamine, N,N-diisopropylethylamine, morpholine, cyclohexylamine, n-propylamine, isopropylamine, di-n-propylamine, diisopropylamine, tripropylamine, n-butylamine or isobutylamine.

7. The preparation method according to claim 5, characterized in that: In step (1), the molar ratio of the mixed gel is SiO2:Al2O3:P2O5:template:H2O is (0.001-0.40):1:(0.85-1.25):(1.5-3.0):(20-100), the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the phosphorus source is calculated as P2O5; And / or, in step (1), the ratio of alumina in the seed crystal to the aluminum source in step (1) calculated as alumina is 1.0 wt% to 20 wt%.

8. The preparation method according to claim 5, characterized in that: The crystallization conditions in step (1) are: temperature of 120 to 210° C., time of 12 to 72 hours, stirring or standing; And / or, the hydrothermal treatment conditions in step (2) are: standing and crystallizing at 120-210° C. for 12-72 hours.

9. A method for preparing light olefins by hydrogenating CO2, comprising: The CO2 / H2 mixed gas is contacted with the catalyst described in any one of claims 1 to 4 to react to obtain a product containing light olefins.

10. The method according to claim 9, characterized in that The reaction conditions are as follows: reaction temperature 320-500°C, reaction pressure 0.5-8MPa, volumetric space velocity of the mixed gas 1000-9600h -1 , the volume ratio of CO to CO2 is 0.1~10.0, and the volume ratio of CO to H2 is 0.5~5.0.

Images