Catalyst for preparing low-carbon olefin by hydrogenating CO-CO2 mixed gas as well as preparation and application of catalyst

Abstract

The invention discloses a catalyst for preparing low-carbon olefin through direct hydrogenation of CO-CO2 mixed gas as well as preparation and application of the catalyst. The catalyst comprises a metal oxide and a modified SAPO molecular sieve, wherein the metal oxide has catalytic activity on preparation of low-carbon olefin by direct hydrogenation of a CO-CO2 mixed gas; the modified SAPO molecular sieve is an SAPO coated AlPO core-shell molecular sieve. When the catalyst disclosed by the invention is used for preparing low-carbon olefin through direct hydrogenation of CO-CO2 mixed gas, olefin selectivity is maintained, and meanwhile, the catalyst has relatively high CO conversion rate and relatively low CO2 selectivity.

Description

Technical Field

[0001] The present invention relates to a catalyst for preparing light olefins, and in particular to a catalyst for preparing light olefins by hydrogenating a CO-CO2 mixed gas, and the preparation and application of the catalyst. Background Art

[0002] Olefins are the most important basic chemical raw materials. From low-carbon olefins (C2=-C4=, i.e. ethylene, propylene and butene), a variety of chemical raw materials and products can be prepared, affecting all aspects of people's daily lives. With the rapid development of the economy and the progress of society, the demand for olefin raw materials is increasing. The traditional route for producing olefins mainly relies on petroleum resources, but due to the limitation of raw material sources, it is urgent to develop non-petroleum route technologies.

[0003] Through the coal chemical process, a route for producing olefins from coal can be opened up. Through the water-gas conversion technology, coal resources can be converted into carbon monoxide, water, carbon dioxide and hydrogen. Among them, carbon monoxide hydrogenation (synthesis gas) is an important platform for C1 conversion. Through the Fischer-Tropsch synthesis process (Science, 2012, 335, 835) or the coupled conversion process (Science, 2016, 351, 1065), synthesis gas can be directly converted to produce low-carbon olefins. However, during the synthesis gas conversion process, a large amount of carbon dioxide will be generated. Carbon dioxide can be directly separated and discharged, but it will lead to an increase in the amount of carbon dioxide emitted into the atmosphere, which will aggravate the greenhouse effect on the one hand and cause a huge waste of carbon resources on the other. The separated and enriched carbon dioxide can be effectively utilized through chemical conversion. For example, Professor Wang Ye of Xiamen University (ACS Catal. 2020, 10, 8303–8314) achieved a CO2 conversion rate of 13% and a selectivity of 86% for C2-C4 olefins in organic compounds at 370°C by coupling ZnGa2O4 metal oxide with SAPO-34 molecular sieve to form a bifunctional catalyst.

[0004] Although the technology of hydrogenating carbon monoxide and carbon dioxide to produce olefins has received extensive attention and research, the technology of hydrogenating carbon monoxide-carbon dioxide mixture has been rarely studied. This is mainly because carbon dioxide is a by-product of carbon monoxide hydrogenation. Too high a concentration of carbon dioxide will greatly reduce the efficiency of carbon monoxide hydrogenation and poor catalyst conversion performance.

[0005] In summary, it is of far-reaching significance to develop catalysts with high conversion efficiency for CO-CO2 mixed gas hydrogenation technology and realize efficient conversion of CO-CO2 mixed gas hydrogenation. Summary of the invention

[0006] Based on the defects of the coupled catalyst system in the prior art, such as low reaction activity, low target product selectivity and high by-product selectivity, the present invention provides a catalyst for hydrogenating a CO-CO2 mixed gas to produce light olefins, and its preparation and application. When the catalyst is used for the hydrogenation of a CO-CO2 mixed gas to produce light olefins, it can significantly improve the carbon monoxide conversion efficiency and reduce the carbon dioxide selectivity while maintaining the olefin selectivity.

[0007] The first aspect of the present invention provides a catalyst for direct hydrogenation of a CO-CO2 mixed gas to produce light olefins, comprising a metal oxide and a modified SAPO molecular sieve; the metal oxide is a metal oxide having catalytic activity for direct hydrogenation of a CO-CO2 mixed gas to produce light olefins; the modified SAPO molecular sieve is a SAPO@AlPO core-shell molecular sieve.

[0008] In the above technical solution, the metal oxide is selected from InZr b Cr y O x 、ZnZr b Cr y O x 、InZr b Al y O x 、InCr b Ce y O x 、ZnZr b Al y O x 、InZr b ZnCr b O x 、InCe b ZnCr b O x 、InZr b O x -InCr b O x 、InAl b O x -InCr b O x 、InCe b O x -ZnCr b O x 、MnAl b O x -InCr b O x 、MnZr b O x -InCr b O x 、CoAlb O x -InCr b O x and FeAl b O x -InCr b O x One or more of, wherein b = 1 / 4 to 3 / 1, y = 1 / 4 to 3 / 1; preferably, the metal oxide is preferably selected from InZr b Cr y O x 、ZnZr b Cr y O x 、InZr b ZnCr b O x 、InCe b ZnCr b O x and InZr b O x -InCr b O x One or more of the following, wherein b=1 / 4 to 3 / 1, y=1 / 4 to 3 / 1.

[0009] In the above technical solution, the metal oxide is selected from InZr b Cr y O x 、ZnZr b Cr y O x 、InZr b Al y O x 、InCr b Ce y O x 、ZnZr b Al y O x 、InZr b ZnCr b O x 、InCe b ZnCr b O x 、InZr b O x -InCr b O x 、InAl b O x -InCr b O x 、InCe b O x -ZnCrb O x 、MnAl b O x -InCr b O x 、MnZr b O x -InCr b O x 、CoAl b O x -InCr b O x and FeAl b O x -InCr b O x When there are multiple types of metal oxides, b in different types of metal oxides may be the same or different, y in different types of metal oxides may be the same or different, and x in different types of metal oxides may be the same or different.

[0010] In the above technical scheme, the SAPO@AlPO core-shell molecular sieve comprises a SAPO molecular sieve core and an AlPO molecular sieve shell, wherein 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; the AlPO molecular sieve is selected from one or more of AlPO-14, AlPO-17, AlPO-18, AlPO-34, AlPO-35, AlPO-42, AlPO-44, AlPO-47, and AlPO-56.

[0011] In the above technical solution, the weight ratio of the SAPO molecular sieve core to the AlPO molecular sieve shell in the modified SAPO molecular sieve is 1000:1-2:1, preferably 100:1-5:1, more preferably 50:1-10:1, and even more preferably 80:1-15:1.

[0012] In the above technical solution, the silicon-aluminum molar ratio SiO2 / Al2O3 of the SAPO molecular sieve core in the modified SAPO molecular sieve is 0.001-0.60, preferably 0.01-0.40, and more preferably 0.05-0.20; the mass ratio of metal oxide to molecular sieve in the metal oxide-molecular sieve composite is 1:8-8:1, preferably 1:3-3:1.

[0013] The second aspect of the present invention provides a method for preparing the above catalyst, comprising the following steps:

[0014] (1) mixing a phosphorus source, an aluminum source, a silicon source, a template agent and water uniformly to obtain a SAPO molecular sieve synthesis mixed gel;

[0015] (2) adding molecular sieve seed crystals to the mixed gel and subjecting it to hydrothermal crystallization treatment to obtain SAPO molecular sieve raw powder;

[0016] (3) mixing a phosphorus source, an aluminum source, a template agent and water uniformly to obtain an AlPO molecular sieve synthesis mixed gel;

[0017] (4) adding the prepared SAPO molecular sieve to the AlPO mixed gel and performing a hydrothermal crystallization treatment to obtain SAPO@AlPO molecular sieve raw powder;

[0018] (5) Mixing the metal oxide and the SAPO@AlPO core-shell structure molecular sieve to obtain the catalyst.

[0019] 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 pseudo-boehmite, boehmite, aluminum sol, aluminum isopropoxide, tert-butyl aluminum, aluminate, activated alumina; and the template agent 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.

[0020] In the above technical scheme, the molar ratio of the mixed gel in step (1) is SiO2:Al2O3:P2O5:template:H2O is 0.001-0.40:1:0.85-1.25:1.5-3.0:20-100, wherein the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the phosphorus source is calculated as P2O5.

[0021] In the above technical scheme, in step (2), molecular sieve seeds are added to the mixed gel, wherein the seeds are solid powder or pre-crystallized mother liquor of the molecular sieve corresponding to the core, and the proportion of alumina in the seeds to the aluminum source in step (1) is 1.0wt% to 20wt% calculated as alumina.

[0022] In the above technical solution, the crystallization conditions in step (2) and step (4) are independently selected from: temperature of 120 to 210° C., time of 12 to 72 hours, stirring or standing.

[0023] In the above technical solution, after crystallization in step (2) and step (4), conventional post-treatment steps such as separation, washing, drying and calcination can be adopted, 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 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 1-5 hours.

[0024] In the above technical scheme, the molar ratio of the mixed gel in step (3) is Al2O3:P2O5:template:H2O is 1:0.85~1.25:1.5~3.0:20~100, wherein the aluminum source is calculated as Al2O3 and the phosphorus source is calculated as P2O5.

[0025] In the above technical solution, the metal oxide in step (5) can be prepared by conventional methods, such as metal oxide InZr b Cr y O x or InZr b ZnCr b 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 -InCr b O x InZr was first prepared by precipitation in solution. b O x and InCr b O x , and then prepared by physical mixing method.

[0026] The third aspect of the present invention provides a method for directly hydrogenating a CO-CO2 mixed gas to produce light olefins, wherein the CO / CO2 / H2 mixed gas is contacted with the above-provided catalyst to react to obtain a product containing light olefins.

[0027] 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.

[0028] In the above technical scheme, the reaction conditions are as follows: reaction temperature 320-500°C, reaction pressure 0.5-8MPa, volume 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.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The inventor has found through research that when a catalyst comprising a metal oxide having catalytic activity for direct hydrogenation of CO-CO2 mixed gas to produce light olefins and a modified SAPO molecular sieve is used for direct hydrogenation of CO-CO2 mixed gas to produce light olefins, the carbon monoxide conversion rate can be significantly improved, and the olefin selectivity can be maintained at a high level while the carbon dioxide selectivity can be reduced. The catalyst preparation method of the present invention is simple, the raw materials are cheap and readily available, and the preparation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the XRD pattern of the SAPO-34@AlPO-18 molecular sieve obtained in Example 1;

[0032] Figure 2 is a SEM image of the SAPO-34@AlPO-18 molecular sieve obtained in Example 1;

[0033] Figure 3 This is the silicon element distribution diagram of the SAPO-34@AlPO-18 molecular sieve obtained in Example 1. DETAILED DESCRIPTION

[0034] 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.

[0035] In the present invention, the test conditions of XRD and SEM are as follows:

[0036] 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.

[0037] SEM test conditions: Japan Hitachi S4800 field emission scanning electron microscope was used for testing.

[0038] In the present invention, the distribution of silicon element in the molecular sieve is tested by photoelectron spectroscopy.

[0039] In the present invention, the components after the reaction are separated and quantitatively analyzed by gas chromatography, and the calculation formula of CO conversion rate and C2-C4 olefin selectivity is:

[0040] CO conversion rate = (CO content in raw material - CO content in reaction product) / CO content in raw material × 100%, by volume;

[0041] CO2 selectivity generated by CO conversion = moles of CO converted to CO2 / total moles of CO converted × 100%;

[0042] C2-C4 olefin selectivity = moles of CO converted to C2-C4 olefins / (total moles of CO converted - moles of CO converted to CO2) x 100%.

[0043] [Example 1]

[0044] (1) InZr b Cr y O x The mixed oxides were prepared as follows:

[0045] Weigh a certain amount of zirconium nitrate, chromium nitrate and indium nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Cr at 4 / 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation, filter and wash after precipitation, dry at 100°C overnight, and calcine at 500°C for 4h.

[0046] (2) SAPO-34 molecular sieve was prepared according to the following steps:

[0047] Phosphoric acid, pseudo-boehmite, silica sol, and triethylamine (TEA) are used as phosphorus source, aluminum source, silicon source, and template agent, respectively, with a molar ratio of SiO2:Al2O3:P2O5:TEA:H2O=0.10:1:0.95:3:50. After stirring at room temperature (25°C) for 1 hour, SAPO-34 molecular sieve is added as a seed (the ratio of alumina in the seed to the aluminum source in the feed is 10.0wt% in terms of alumina), stirred evenly, and then allowed to stand at 170°C for crystallization for 24 hours. The obtained solid is washed with deionized water until neutral, separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-34 molecular sieve powder. The obtained molecular sieve has a silicon-aluminum molar ratio SiO2 / Al2O3 of 0.10.

[0048] (3) SAPO-34@AlPO-18 core-shell molecular sieve was prepared according to the following steps:

[0049] Phosphoric acid, aluminum isopropoxide, and tetraethylammonium hydroxide (TEAOH) are used as phosphorus source, aluminum source, and template agent, respectively, with a molar ratio of Al2O3:P2O5:TEAOH:H2O=1.0:2.0:4.0:50. Stir evenly at room temperature (25°C), add SAPO-34 molecular sieve powder to the above gel, continue stirring for 1 hour, and then stand at 170°C for crystallization for 24 hours. Separate the solid, dry it, and calcine it at 550°C in a muffle furnace for 6 hours to obtain SAPO-34@AlPO-18 core-shell molecular sieve powder. The XRD pattern of the obtained SAPO-34@AlPO-18 core-shell molecular sieve powder is as follows Figure 1 As shown in; the obtained SAPO-34@AlPO-18 core-shell molecular sieve powder SEM Figure 2 The silicon element distribution diagram of the obtained SAPO-34@AlPO-18 core-shell molecular sieve powder is shown in Figure 3 as shown in .

[0050] (4) Catalyst preparation and reaction:

[0051] SAPO-34@AlPO-18 core-shell molecular sieve powder and metal oxide InZr b Cr y O x The metal oxide-molecular sieve bifunctional catalyst is formed by physically mixing in a mass ratio of 1:1, tableting and crushing to 20-40 mesh. The catalyst composition is shown in Table 1.

[0052] 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, then switched to a mixture of carbon monoxide / carbon dioxide and hydrogen (CO:CO2:H2=3:1:3) at 390°C, 4.0MPa, 5000h. -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.

[0053] [Example 2]

[0054] (1) InZr b Cr y O x The mixed oxides were prepared as follows:

[0055] Weigh a certain amount of zirconium nitrate, chromium nitrate and indium nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Cr at 3 / 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation, filter and wash after precipitation, dry at 100°C overnight, and calcine at 500°C for 4 hours.

[0056] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0057] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0058] (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.

[0059] [Example 3]

[0060] (1) InZr b Cr y O x The mixed oxides were prepared as follows:

[0061] Weigh a certain amount of zirconium nitrate, chromium nitrate and indium nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Cr at 2 / 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation, filter and wash after precipitation, dry at 100°C overnight, and calcine at 500°C for 4 hours.

[0062] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0063] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0064] (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.

[0065] [Example 4]

[0066] (1) InZr b Cr y O x The mixed oxides were prepared as follows:

[0067] Weigh a certain amount of zirconium nitrate, chromium nitrate and indium nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Cr at 1 / 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation, filter and wash after precipitation, dry at 100°C overnight, and calcine at 500°C for 4 hours.

[0068] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0069] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0070] (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.

[0071] [Example 5]

[0072] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0073] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0074] (3) SAPO-34@AlPO-17 molecular sieve was prepared according to the following steps:

[0075] Phosphoric acid, aluminum isopropoxide and cyclohexylamine (CHA) are used as phosphorus source, aluminum source and template respectively, with a molar ratio of Al2O3:P2O5:CHA:H2O=1.0:1.0:1.2:50. The mixture is stirred evenly at room temperature. SAPO-34 molecular sieve powder is added to the above gel. After stirring for 1 hour, the mixture is allowed to stand and crystallize at 170°C for 24 hours. The solid is separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-34@AlPO-17 core-shell molecular sieve powder.

[0076] (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.

[0077] [Example 6]

[0078] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0079] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0080] (3) SAPO-34@AlPO-34 molecular sieve was prepared according to the following steps:

[0081] Phosphoric acid, aluminum isopropoxide and triethylamine (TEA) were used as phosphorus source, aluminum source and template respectively, with a molar ratio of Al2O3:P2O5:TEA:H2O=1.0:1.0:3.0:50. The mixture was stirred evenly at room temperature. SAPO-34 molecular sieve powder was added to the above gel. After stirring for 1 hour, the mixture was allowed to stand and crystallize at 170°C for 24 hours. The solid was separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-34@AlPO-34 core-shell molecular sieve powder.

[0082] (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.

[0083] [Example 7]

[0084] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0085] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0086] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0087] (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.

[0088] [Example 8]

[0089] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0090] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0091] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0092] (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.

[0093] [Example 9]

[0094] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0095] (2) SAPO-18 molecular sieve is prepared according to the following process:

[0096] Phosphoric acid, aluminum isopropoxide, silica sol and tetraethylammonium hydroxide (TEAOH) are used as phosphorus source, aluminum source, silicon source and template respectively, with a molar ratio of SiO2:Al2O3:P2O5:TEA:H2O=0.10:1:2.0:4.0:50. After stirring at room temperature for 1 hour, SAPO-18 molecular sieve is added as seed (the ratio of alumina in the seed to the aluminum source in the feed as alumina is 10.0wt%). After stirring evenly, the mixture is allowed to stand at 170°C for crystallization for 24 hours. The obtained solid is washed with deionized water until neutral, the solid is separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-34 molecular sieve powder.

[0097] (3) SAPO-18@AlPO-18 core-shell molecular sieve was prepared according to the following steps:

[0098] Phosphoric acid, aluminum isopropoxide and tetraethylammonium hydroxide (TEAOH) are used as phosphorus source, aluminum source and template respectively, with a molar ratio of Al2O3:P2O5:TEAOH:H2O=1.0:2.0:4.0:50. The mixture is stirred evenly at room temperature. SAPO-34 molecular sieve powder is added to the above gel. After stirring for 1 hour, the mixture is allowed to stand and crystallize at 170°C for 24 hours. The solid is separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-18@AlPO-18 core-shell molecular sieve powder.

[0099] (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.

[0100] [Example 10]

[0101] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0102] (2) SAPO-17 molecular sieve is prepared according to the following process:

[0103] Phosphoric acid, aluminum isopropoxide, silica sol and cyclohexylamine (CHA) are used as phosphorus source, aluminum source, silicon source and template respectively, with a molar ratio of SiO2:Al2O3:P2O5:CHA:H2O=0.10:1:0.95.0:1.2:50. After stirring at room temperature for 1 hour, SAPO-17 molecular sieve is added as seed (the ratio of alumina in the seed to the aluminum source in the feed as alumina is 10.0wt%), and after stirring evenly, the mixture is allowed to stand at 170°C for crystallization for 24 hours. The obtained solid is washed with deionized water until neutral, the solid is separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-17 molecular sieve powder.

[0104] (3) SAPO-17@AlPO-18 core-shell molecular sieve was prepared according to the following steps:

[0105] Phosphoric acid, aluminum isopropoxide and tetraethylammonium hydroxide (TEAOH) are used as phosphorus source, aluminum source and template respectively, with a molar ratio of Al2O3:P2O5:TEAOH:H2O=1.0:2.0:4.0:50. The mixture is stirred evenly at room temperature. The SAPO-17 molecular sieve powder is added to the above gel. After stirring for 1 hour, the mixture is allowed to stand and crystallize at 170°C for 24 hours. The solid is separated, dried, and calcined in a muffle furnace at 550°C for 6 hours to obtain SAPO-17@AlPO-18 core-shell molecular sieve powder.

[0106] (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.

[0107] [Example 11]

[0108] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0109] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0110] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0111] (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.

[0112] [Example 12]

[0113] (1) InZr b ZnCr b O x The mixed oxides were prepared as follows:

[0114] Weigh a certain amount of indium nitrate, zirconium nitrate, zinc nitrate and chromium nitrate solids and disperse them in water, keeping the molar ratio of In / Zr / Zn / Cr at 1 / 1 / 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation, filter and wash after precipitation, dry at 100°C overnight, and calcine at 500°C for 4 hours.

[0115] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0116] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0117] (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.

[0118] [Example 13]

[0119] (1)InCe b ZnCr b O x The mixed oxides were prepared as follows:

[0120] Weigh a certain amount of indium nitrate, cerium nitrate, zinc nitrate and chromium nitrate solids and disperse them in water, keeping the molar ratio of In / Ce / Zn / Cr at 1 / 1 / 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation, filter and wash after precipitation, dry at 100°C overnight, and calcine at 500°C for 4 hours.

[0121] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0122] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0123] (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.

[0124] [Example 14]

[0125] (1)InZrO x -InCrO x The mixed oxide was prepared as follows.

[0126] Preparation of InZrO x Mixed oxides: Weigh a certain amount of zirconium nitrate and indium nitrate solids and disperse them in water, keeping the In / Zr molar ratio at 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation, filter and wash after precipitation, dry at 100°C overnight, and calcine at 500°C for 4 hours.

[0127] Preparation of InCrO xMixed oxides: Weigh a certain amount of indium nitrate and chromium nitrate solids and disperse them in water, keeping the In / Cr molar ratio at 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation, filter and wash after precipitation, dry at 100°C overnight, and calcine at 500°C for 4 hours.

[0128] InZrO x Mixed oxides and InCrO x The mixed oxides were physically mixed, maintaining an In / Zr / Cr molar ratio of 2 / 1 / 1 in the final mixture.

[0129] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0130] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0131] (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.

[0132] [Comparative Example 1]

[0133] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0134] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0135] (3) Catalyst preparation and reaction:

[0136] SAPO-34 molecular sieve powder and InZr b Cr y O x The mixed oxides are physically mixed in a mass ratio of 1:1, tableted and crushed to 20-40 meshes to form a metal oxide-molecular sieve bifunctional catalyst. The catalyst composition is shown in Table 3.

[0137] (4) The catalytic reaction was carried out according to [Example 1]. The catalyst composition is shown in Table 3. The reaction results are shown in Table 2.

[0138] [Comparative Example 2]

[0139] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0140] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0141] (3) AlPO-18 molecular sieve was prepared according to [Example 1].

[0142] 0.25 g AlPO-18 molecular sieve solid powder was dispersed in 20 g water and stirred to disperse evenly; 9.75 g SAPO-34 molecular sieve was added to the above solution and stirred to mix evenly; after centrifugation, AlPO-18 and SAPO-34 blended molecular sieves were obtained, named SAPO-34 / AlPO-18.

[0143] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 3. The reaction results are shown in Table 2.

[0144] [Comparative Example 3]

[0145] (1)InZrO x The mixed oxides were prepared according to the following steps:

[0146] Weigh a certain amount of zirconium nitrate and indium nitrate solids and disperse them in water, keeping the In / Zr molar ratio of 1 / 1, and stir until completely dissolved; weigh a certain amount of (NH4)2CO3 solid and dissolve it in water to prepare a 0.1 mol / L solution. Add the two aqueous solutions to the beaker at the same time for co-precipitation. After precipitation, filter and wash, dry at 100°C overnight, and calcine at 500°C for 4 hours.

[0147] (2) SAPO-34 molecular sieve was prepared according to [Example 1].

[0148] (3) SAPO-34@AlPO-18 molecular sieve was prepared according to [Example 1].

[0149] (4) Catalyst preparation and reaction were carried out according to [Example 1]. The catalyst composition is shown in Table 3. The reaction results are shown in Table 2.

[0150] [Comparative Example 4]

[0151] (1) InZr b Cr y O x The mixed oxide was prepared according to [Example 3].

[0152] (2) AlPO-18 molecular sieve was prepared according to [Example 1].

[0153] (3) Catalyst preparation and reaction:

[0154] AlPO-18 molecular sieve powder and InZr b Cr y O xThe mixed oxides are physically mixed in a mass ratio of 1:1, tableted and crushed to 20-40 meshes to form a metal oxide-molecular sieve bifunctional catalyst. The catalyst composition is shown in Table 3.

[0155] (4) The catalytic reaction was carried out according to [Example 1]. The catalyst composition is shown in Table 3. The reaction results are shown in Table 2.

[0156] Table 1

[0157]

[0158] Table 2

[0159] CO conversion rate / % <![CDATA[CO2 selectivity / %]]> C2-C4 olefin selectivity / % Example 1 44.3 36.2 82.2 Example 2 42.4 35.7 83.0 Example 3 45.9 31.2 82.7 Example 4 42.4 34.5 83.4 Example 5 42.5 35.0 85.8 Example 6 42.8 34.2 85.4 Example 7 43.7 33.7 85.0 Example 8 43.0 34.1 83.8 Example 9 42.7 33.9 85.1 Example 10 40.7 33.1 85.3 Embodiment 11 40.3 33.1 86.2 Example 12 39.1 35.7 81.2 Example 13 37.9 36.7 80.9 Embodiment 14 40.9 32.7 81.9 Comparative Example 1 30.4 46.7 81.0 Comparative Example 2 29.2 47.5 82.5 Comparative Example 3 35.2 47.5 75.1 Comparative Example 4 17.6 46.9 70.3

[0160] 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 direct hydrogenation of a CO-CO2 mixed gas to produce light olefins, comprising a metal oxide and a modified SAPO molecular sieve; the metal oxide is a metal oxide having catalytic activity for direct hydrogenation of a CO-CO2 mixed gas to produce light olefins; the modified SAPO molecular sieve is a SAPO@AlPO core-shell molecular sieve.

2. The catalyst according to claim 1, characterized in that: The metal oxide is selected from InZr b Cr y O x 、ZnZr b Cr y O x 、InZr b Al y O x 、InCr b Ce y O x 、ZnZr b Al y O x 、InZr b ZnCr b O x 、InCe b ZnCr b O x 、InZr b O x -InCr b O x 、InAl b O x -InCr b O x 、InCe b O x -ZnCr b O x 、MnAl b O x -InCr b O x 、MnZr b O x -InCr b O x 、CoAl b O x -InCr b O x and FeAl b O x -InCr b O x One or more of, wherein b = 1 / 4 to 3 / 1, y = 1 / 4 to 3 / 1; preferably, the metal oxide is selected from InZr b Cr y O x 、ZnZr b Cr y O x 、InZr b ZnCr b O x 、InCe b ZnCr b O x and InZr b O x -InCr b O x One or more of the following, wherein b=1 / 4 to 3 / 1, y=1 / 4 to 3 / 1.

3. The catalyst according to claim 1, characterized in that: The SAPO@AlPO core-shell molecular sieve, wherein 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; the AlPO molecular sieve is selected from one or more of AlPO-14, AlPO-17, AlPO-18, AlPO-34, AlPO-35, AlPO-42, AlPO-44, AlPO-47, and AlPO-56.

4. The catalyst according to claim 1, characterized in that: In the modified SAPO molecular sieve, the weight ratio of the SAPO molecular sieve core to the AlPO molecular sieve shell is 1000:1 to 2:1, preferably 100:1 to 5:1, more preferably 50:1 to 10:1, and even more preferably 80:1 to 15:

1.

5. The catalyst according to claim 1, characterized in that: In the modified SAPO molecular sieve, the silicon-aluminum molar ratio SiO2 / Al2O3 of the SAPO molecular sieve core is 0.001 to 0.60, preferably 0.01 to 0.40, and more preferably 0.05 to 0.20; And / or, the mass ratio of the metal oxide to the modified SAPO molecular sieve is 1:8 to 8:1, preferably 1:3 to 3:

1.

6. A method for preparing a catalyst according to any one of claims 1 to 5, comprising the following steps: (1) mixing a phosphorus source, an aluminum source, a silicon source, a template agent and water uniformly to obtain a SAPO molecular sieve synthesis mixed gel; (2) adding molecular sieve seed crystals to the mixed gel obtained in step (1), and subjecting the mixture to hydrothermal crystallization to obtain SAPO molecular sieve raw powder; (3) mixing a phosphorus source, an aluminum source, a template agent and water uniformly to obtain an AlPO molecular sieve synthesis mixed gel; (4) adding the SAPO molecular sieve raw powder obtained in step (2) to the AlPO molecular sieve synthetic mixed gel obtained in step (3) to perform hydrothermal crystallization treatment to obtain SAPO@AlPO molecular sieve raw powder; (5) Mixing the metal oxide with the SAPO@AlPO molecular sieve raw powder obtained in step (4) to obtain the catalyst.

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

8. The preparation method according to claim 6, characterized in that: In step (1), the molar ratio of the mixed gel SiO2:Al2O3:P2O5:template:H2O is 0.001-0.40:1:0.85-1.25:1.5-3.0:20-100, wherein 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 (2), molecular sieve seed crystals are added to the mixed gel, wherein the ratio of alumina in the seed crystals to the aluminum source in step (1) is 1.0 wt% to 20 wt% calculated as alumina; And / or, in step (3), the molar ratio of the mixed gel Al2O3:P2O5:template:H2O is 1:0.85-1.25:1.5-3.0:20-100, wherein the aluminum source is calculated as Al2O3 and the phosphorus source is calculated as P2O5.

9. The preparation method according to claim 6, characterized in that: The crystallization conditions in steps (2) and (4) are independently selected from: temperature of 120 to 210° C., time of 12 to 72 hours, stirring or standing.

10. A method for directly hydrogenating a CO / CO2 mixed gas to produce light olefins, comprising: The CO / CO2 / H2 mixed gas is contacted with the catalyst described in any one of claims 1 to 5 to react to obtain a product containing light olefins.

11. The method according to claim 10, 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.

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