A cobalt-based catalyst, its preparation method and application

Abstract

The present invention relates to a cobalt-based catalyst, a preparation method thereof and an application thereof. The present invention provides a catalyst, which comprises a carrier and an active component; the carrier is a pure silica molecular sieve substituted by non-active elements; the active elements in the active component include Co; wherein, Co is loaded in the carrier in a single-site structure; Co exists in the forms of Co—O—Si, Co—O—non-active element and Co—O; Co is connected to the carrier through Co—O—Si and Co—O—non-active element; the coordination number of Co—O is 3. The cobalt-based catalyst is prepared by a one-step hydrothermal synthesis strategy. The catalyst prepared by the present invention exhibits excellent catalytic activity and product propylene selectivity in the propane dehydrogenation reaction, far exceeding other Co-based catalysts of the same type, more than 10 times the activity of the currently reported most excellent supported Co-based catalyst, and even exceeding the active Pt catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a cobalt-based catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Propylene is one of the most important raw materials for daily production and daily necessities, and can be used to produce a variety of high-value-added commodities and chemicals. Traditional methods for obtaining propylene include naphtha cracking and fluid catalytic cracking of heavy oil, but they are limited by high energy consumption and low selectivity. Propane dehydrogenation (PDH), as a method for specifically producing propylene, has been increasingly popular in recent years. In addition, with the development of hydraulic fracturing technology, the extraction of a large amount of shale gas rich in propane has become easier, making the raw materials for propane dehydrogenation cheap and abundant.

[0003] At present, the propane dehydrogenation catalysts used in industry are mainly divided into platinum-based and chromium-based catalysts. Platinum-based catalysts have excellent propane dehydrogenation activity due to their unique affinity for C-H bonds, but they are prone to carbon deposition and sintering and deactivate. In addition, the high price is also a factor limiting the development of platinum-based catalysts. Chromium-based catalysts are inexpensive and have high catalytic Lewis acid activity, but they are extremely prone to triggering other side reactions, reducing the reaction selectivity while quickly deactivating themselves, resulting in frequent regeneration. In addition, chromium is a heavy metal, and its toxicity and environmental pollution cannot be ignored. Therefore, the development of inexpensive and highly active propane dehydrogenation catalysts is a hot topic in the current scientific research community and industrial community.

[0004] Cobalt-based catalysts are considered to be popular candidates to replace platinum-based catalysts due to their extremely high stability and anti-sintering performance. Al2O3, SiO2, etc. are the most common carriers for making cobalt species, but during the high-temperature conversion process of PDH, small-sized cobalt species will undergo severe sintering and rapidly reduce their activity.

[0005] Molecular sieves with ordered micropores and mesopores are considered to be ideal carriers for confining and anchoring metal nanoparticles. However, when using traditional impregnation methods to load metal particles on molecular sieves, generally large-sized metal particles will be produced and the dispersion is very poor. Recently, Liu Jian et al. encapsulated cobalt oxide clusters into the pores of pure silica molecular sieves by ligand stabilization method, showing good anti-sintering performance and good cyclic stability in propane dehydrogenation reaction. However, despite adding a relatively large amount of cobalt, the activity of the reaction is still very low.

[0006] At present, the propane dehydrogenation catalysts mainly have the following disadvantages: (1) high cost and easy carbon deposition and sintering (platinum-based catalysts); (2) many side reactions, frequent regeneration, and environmental pollution (chromium-based catalysts); (3) slow reaction rate and too low activity (cobalt-based catalysts).

[0007] Therefore, it is crucial and challenging to develop a molecular sieve-supported highly dispersed Co-based catalyst with high activity and stability. Summary of the Invention

[0008] Aiming at the key technical problems of the existing supported platinum-based metal catalysts, such as high cost, low activity and poor stability of the inactive catalysts in propane dehydrogenation reaction, the present invention provides a cobalt (Co)-based catalyst, its preparation method and application. Through a one-step hydrothermal synthesis strategy, the present invention constructs an inactive element-substituted molecular sieve encapsulated single-site Co-based catalytic material with a brand-new active site structure. The catalyst prepared by the present invention exhibits excellent catalytic activity and propane selectivity in propane dehydrogenation reaction, far exceeding the activity and propylene selectivity of other Co-based catalysts of the same type, more than 10 times the activity of the currently reported most excellent supported Co-based catalyst, and even exceeding the active Pt catalyst.

[0009] The present invention is realized by the following technical solutions:

[0010] The first object of the present invention is to provide a catalyst, which includes a carrier and an active component;

[0011] The carrier is an inactive element-substituted pure silica molecular sieve; the main component of the pure silica molecular sieve is SiO2.

[0012] The active element in the active component includes Co; wherein, Co is loaded in the carrier in a single-site structure;

[0013] Co exists in the catalyst in the forms of Co-O-Si, Co-O-inactive element and Co-O; wherein, Co is connected to the carrier through Co-O-Si and Co-O-inactive element; and isolated Co-O bonds also exist. The coordination number of Co-O is 3 and the valence is +2.

[0014] In an embodiment of the present invention, the loading amount of the active element in the catalyst is 0.1 wt% to 0.88 wt%; wherein, the loading amount refers to the mass percentage of the active metal element Co in the catalyst.

[0015] In an embodiment of the present invention, one or more of the following conditions are satisfied:

[0016] The pure silica molecular sieve in the inactive element-substituted pure silica molecular sieve is Silicalite-1 molecular sieve;

[0017] The inactive element includes Mo or W; the inactive element exists in the form of +6 valence Mo ions or W ions, and is connected to the Si atoms on the framework through oxygen atoms to form a single-site structure.

[0018] The inactive element is a non-noble metal element;

[0019] The molar ratio of the inactive element to the active element is x, where 0 < x ≤ 80:1.

[0020] Preferably, the catalyst has the following general formula:

[0021] Co x％ @yM-S-1 Formula I

[0022] where M is other elements; x ≤ 0.88; y ≤ 0.08; S-1 is pure silica molecular sieve; "@" means Co species are encapsulated inside the molecular sieve crystal.

[0023] Preferably, in Formula I, x is 0.1, 0.11, 0.2, 0.22, 0.4, 0.44, 0.8 or 0.88.

[0024] Preferably, in Formula I, y is 0.01, 0.02, 0.04, 0.06 or 0.08.

[0025] The second object of the present invention is to provide a method for preparing a catalyst, comprising the following steps:

[0026] (1) Mix a metal complex, a template agent, a silicon source and an inactive element source, and perform hydrothermal crystallization in water to obtain precursor I;

[0027] (2) Calcinate the precursor I obtained in step (1) in air, perform ion exchange by adding an ammonium salt, and then calcinate to obtain the catalyst.

[0028] In one embodiment of the present invention, in step (1), the metal complex is selected from one or more of [T(NH2CH2CH2NH2)3]Cl2, [T(NH2CH2CH2NH2)3](NO3)2, [T(NH2CH2CH2NH2)3](OAc)2, [T(NH2CH2CH2NH2)3]SO4, [T(NH2CH2CH2NHCH2HCH2NH2)3]Cl2, [T(NH2CH2CH2NHCH2HCH2NH2)3](NO3)2, [T(NH2CH2CH2NHCH2HCH2NH2)3](OAc)2, [T(NH2CH2CH2NHCH2HCH2NH2)3]SO4, [T-NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2]Cl2, [T-NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2](NO3)2, [T-NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2](OAc)2, [T-NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2]SO4, [T-NH2CH2CH2(NHCH2CH2)2NH2]Cl2, [T-NH2CH2CH2(NHCH2CH2)2NH2](NO3)2, [T-NH2CH2CH2(NHCH2CH2)2NH2](OAc)2, [T-NH2CH2CH2(NHCH2CH2)2NH2]SO4; wherein, T is the metal element in the metal complex; preferably, the T is an active element; more preferably, the T is Co.

[0029] Preferably, the method for preparing the metal complex comprises the following steps: adding the metal salt corresponding to T into a mixed solution of an organic amine ligand and water, and stirring to obtain the metal complex.

[0030] The stirring condition is stirring at 25 °C for 1 to 3 hours;

[0031] The volume ratio of the organic amine ligand to water is 0.1 to 0.3:1;

[0032] The metal salt is selected from cobalt chloride, cobalt nitrate, cobalt acetate or cobalt sulfate;

[0033] The organic amine ligand is selected from one or more of ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

[0034] In one embodiment of the present invention, in step (1), the template agent is selected from one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrabutylammonium hydroxide and tetrabutylphosphonium hydroxide;

[0035] The silicon source is selected from one or more of tetraethyl orthosilicate, fumed silica, silica sol, and sodium silicate; the SiO2 content in the silica sol = 40 wt%.

[0036] The non-active element source is selected from a molybdenum source or a tungsten source.

[0037] The molybdenum source is selected from one or more of sodium molybdate, ammonium molybdate, potassium molybdate, molybdenum ethylenediaminetetraacetate, and molybdenum pentachloride;

[0038] The tungsten source is selected from one or more of potassium tungstate, ammonium tungstate, sodium tungstate, and sodium phosphotungstate.

[0039] In one embodiment of the present invention, in step (1), one or more of the following conditions are satisfied:

[0040] The molar ratio of the template agent to the silicon source is 0.24 - 0.4:1;

[0041] The molar ratio of the metal complex to the silicon source is 0.001 - 0.008:1;

[0042] The molar ratio of the non-active element source to the silicon source is 0.01 - 0.08:1;

[0043] The molar ratio of the water to the silicon source is 20 - 40:1.

[0044] Among them, the molar number of the silicon source is calculated based on the molar number of SiO2; the molar number of the template agent is calculated based on the molar number of the template agent itself;

[0045] The molar number of the metal complex is calculated based on the molar number of the metal element; the molar number of the non-active element source is calculated based on the molar number of molybdenum element or tungsten element.

[0046] In one embodiment of the present invention, one or two of the following conditions are satisfied:

[0047] The conditions for hydrothermal crystallization are: isothermal crystallization at 80°C - 120°C for 8 hours - 48 hours;

[0048] The conditions for heating and calcination are: calcination at 500°C - 700°C for 4 hours - 8 hours.

[0049] The third object of the present invention is to provide a method for propane dehydrogenation, comprising the following steps: contacting a gas containing propane with a catalyst for reaction to carry out propane dehydrogenation;

[0050] The catalyst is the above-mentioned catalyst or the catalyst obtained by the above-mentioned preparation method.

[0051] In one embodiment of the present invention, one or more of the following conditions are satisfied:

[0052] The volume content of propane in the propane-containing gas is 25% to 100%.

[0053] The gas flow rate is 15 mL / min to 100 mL / min.

[0054] The propane-containing gas includes nitrogen and / or hydrogen.

[0055] The temperature of the reaction is 500°C to 600°C.

[0056] The pressure of the reaction is 0.1 MPa to 0.2 MPa.

[0057] The Co@Mo-S-1-IE catalyst synthesized in this application exhibits excellent catalytic activity and catalytic life in the propane dehydrogenation reaction. After reacting at 550°C for 72 h, the conversion rate of propane still remains above 20%, and the selectivity of propylene is as high as above 99%. In contrast, the Co 0.11％ @S-1 and Co 0.11％ / S-1 catalysts have propane conversion rates of only 2.1% and 1.5% throughout the reaction.

[0058] The Co@W-S-1-IE catalyst synthesized in this application exhibits excellent catalytic activity and catalytic life in the propane dehydrogenation reaction. After reacting at 550°C for 7 h, the conversion rate of propane still remains above 15%, and the selectivity of propylene is as high as 98%. In contrast, the Co 0.2％ @S-1 and Co 0.2％ / S-1 catalysts have propane conversion rates of only 6% and 2% throughout the reaction.

[0059] This application first introduces single-site Mo(VI) stabilized single-atom Co into the propane dehydrogenation reaction, greatly improving the catalytic activity and catalytic efficiency of cobalt. Without the introduction of additional hydrogen, the conversion rate at 600°C can reach above 35%, and the selectivity reaches above 97%. The conversion rate at 550°C can reach above 20%, and the selectivity exceeds 99%. During the 72-h on-line reaction process, the activity of the catalyst does not decrease significantly, and after being calcined and regenerated 5 times, the catalytic activity does not drop precipitously. The catalytic performance is far higher than all cobalt-based catalysts reported so far and has great application prospects in actual industrial production.

[0060] This application first introduces single-site W(VI) stabilized single-atom Co into the propane dehydrogenation reaction, greatly improving the catalytic activity and catalytic efficiency of cobalt. Without the introduction of additional hydrogen, the conversion rate at 550°C can reach above 15%, and the selectivity reaches 98%. The catalytic performance is excellent and has great application prospects in actual industrial production.

[0061] In this application, "inactive element substitution" means that a single +6-valent inactive element replaces the position of silicon in the original molecular sieve, is connected to other silicon atoms through oxygen bridge atoms, and is stabilized in the framework of the molecular sieve. There is no inactive element-inactive element bond (Mo-Mo bond or W-W bond) in the inactive nanoparticles or inactive element-O-inactive element bond (Mo-O-Mo bond or W-O-W bond) in the molybdenum oxide nanoparticles; "single atom" means that a single +2-valent Co ion is connected to a silicon atom or an inactive atom through an oxygen bridge atom, and there is no Co-Co bond in the traditional Co single substance or Co-O-Co bond in the cobalt oxide nanoparticles. The structural characteristics of the single site determine that it can be stably fixed in the framework or pores of the molecular sieve under high-temperature conditions, and a synergistic effect is formed between cobalt and the inactive element, improving the activity of propane dehydrogenation.

[0062] The above technical solutions of the present invention have the following advantages compared with the prior art:

[0063] 1) The catalyst provided by this application is a single-atom Co catalyst encapsulated by an inactive element-substituted pure-silica molecular sieve, which exhibits extremely excellent catalytic activity, propylene selectivity and stability in the propane dehydrogenation reaction.

[0064] 2) This application adopts a one-step synthesis strategy. Utilizing the confinement effect of the molecular sieve, by isomorphously substituting the atoms of the inactive element into the pure-silica molecular sieve, the dispersion degree of the Co species is significantly improved, presenting a single-atom distribution state. More importantly, the single-atom Co has a unique and novel structure. The coordination number of Co-O is 3, and the valence is +2. The Co atom is connected to the microporous molecular sieve support through Co-O-Si and Co-O-inactive element chemical bonds, and there are also isolated Co-O bonds. The above structure has excellent propane dehydrogenation activity, and the performance of the prepared catalyst in the propane dehydrogenation reaction is more than 10 times that of the currently reported most excellent supported Co-based catalyst activity, and even exceeds that of the active Pt catalyst.

[0065] 3) The catalyst preparation method described in this application patent is simple in operation and low in cost. The propane dehydrogenation performance of the catalyst is extremely excellent, and it has great practical application prospects. Description of the Drawings

[0066] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to the specific embodiments of the present invention and in combination with the drawings, where

[0067] Figure 1 is the XRD pattern of the catalyst prepared in Example 1, where Figure 1 -A is the XRD pattern of the catalyst with different cobalt contents and a fixed molybdenum content, Figure 1-B is the XRD pattern of catalysts with a fixed cobalt content and different molybdenum contents;

[0068] Figure 2 is (A, B)Co in Example 1 0.11％ STEM photograph of the @0.08Mo-S-1-IE catalyst in Example 1. The bright spots circled in the figure are single-atom molybdenum and cobalt on the framework;

[0069] Figure 3 is Co in Example 1 0.11％ Raman spectrum of @0.08Mo-S-1-IE;

[0070] Figure 4 is the solid UV spectrum of different catalysts in Example 1;

[0071] Figure 5 is the catalytic performance of the PDH reaction on different catalysts in Example 3; among them Figure 5 -A and Figure 5 -C are the propane conversions of different catalysts; Figure 5 -B and Figure 5 -D are the propylene selectivities of different catalysts;

[0072] Figure 6 is Co in Example 3 0.11％ Long-term stability test on the @0.08Mo-S-1-IE catalyst; among them Figure 6 -A is the propane conversion, Figure 6 -B is the propylene selectivity;

[0073] Figure 7 is the XRD pattern of the catalysts prepared in Example 2, among which Figure 7 -A is the XRD pattern of catalysts with a fixed tungsten content and different cobalt contents, Figure 7 -B is the XRD pattern of catalysts with a fixed cobalt content and different tungsten contents;

[0074] Figure 8 is the catalytic performance of the PDH reaction on different catalysts in Example 3; among them Figure 8 -A and Figure 8 -C are the propane conversions of different catalysts; Figure 8 -B and Figure 8 -D are the propylene selectivities of different catalysts;

[0075] Figure 9 is the catalytic performance of the PDH reaction on the Co 0.11％ @0.08Mo-S-1 catalyst without ion exchange in the comparative example: among them Figure 9 -A is the propane conversion; Figure 9 -B is the propylene selectivity. Detailed implementation mode

[0076] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments cited are not intended to limit the present invention.

[0077] Unless otherwise specified, the raw materials in the embodiments of the present application are all purchased through commercial channels. Among them, tetraethyl orthosilicate (TEOS), fumed silica, sodium silicate nonahydrate, tetrapropylammonium hydroxide solution (TPAOH, 25wt%), sodium molybdate dihydrate, potassium molybdate, cobalt chloride hexahydrate, ammonium molybdate tetrahydrate, molybdenum pentachloride, ammonium tungstate, sodium tungstate, potassium tungstate, sodium phosphotungstate, tetraethylenepentamine (TEPA), disodium ethylenediaminetetraacetate and ammonia water (25 - 28wt%) are all purchased from Shanghai Macklin Biochemical Technology Co., Ltd.; cobalt nitrate hexahydrate is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; diethylenetriamine (DETA) and anhydrous cobalt sulfate are purchased from Energy Chemical; cobalt acetate tetrahydrate is purchased from Aladdin (Shanghai) Chemical Technology Co., Ltd. (3A); ethylenediamine is purchased from Sinopharm Chemical Reagent Co., Ltd.; molybdenum pentachloride is purchased from Sigma-Aldrich; deionized water comes from the Direct-Q5 integrated water purification system (18.2MΩ·cm -1 )

[0078] Co 0.11％ / S-1, Co 0.11％ / Mo-S-1 and Co 0.2％ / W-S-1 are synthesized by the equal-volume impregnation method: First, take 1 g of Silicalite-1 molecular sieve, Mo-Silicalite-1 molecular sieve or W-Silicalite-1 molecular sieve calcined to remove the template agent, and add 0.3 mL of a pre-prepared Co(NO3)2 solution with a concentration of 0.062M - 0.113M under stirring. After stirring at 25°C for 3 hours, dry at 80°C for 6 hours. Then, in a pure hydrogen atmosphere at 50 mL / min, heat to 550°C in 2 hours, and then keep at 550°C for 0.5 hours for reduction to obtain Co 0.11％ / S-1, Co 0.11％ / Mo-S-1 catalyst or Co 0.2％ / W-S-1 catalyst.

[0079] Mo / Co 0.11％ @S-1 is synthesized by the excess impregnation method: First, take 1 g of Co calcined to remove the template agent 0.11％The @S-1 molecular sieve was added to 1.5 mL of a 1.5 mg / mL Na2MoO4 solution under stirring. After stirring at 25 °C for 1 h, the water was evaporated at 70 °C and then dried overnight in an 80 °C oven. Subsequently, it was heated to 550 °C in a muffle furnace over 4 hours and then maintained at 550 °C for 6 hours to obtain Mo / Co 0.11％ @S-1 catalyst.

[0080] W / Co 0.2％ @S-1 was synthesized by the method of excess impregnation. First, 1 g of Co from which the template agent had been calcined off 0.2％ The @S-1 molecular sieve was added to 1.5 mL of a 0.045 mg / mL Na2WO4 solution under stirring. After stirring at 25 °C for 1 h, the water was evaporated at 70 °C and then dried overnight in an 80 °C oven. Subsequently, it was heated to 550 °C in a muffle furnace over 4 hours and then maintained at 550 °C for 6 hours to obtain W / Co 0.2％ @S-1 catalyst.

[0081] In the above examples, Mo-S-1 represents Mo-Silicalite-1 molecular sieve, W-S-1 represents W-Silicalite-1 molecular sieve, and S-1 represents Silicalite-1 molecular sieve.

[0082] The analysis methods in the examples of this application are as follows:

[0083] STEM analysis was carried out using a JEOL JEM-ARM300F electron microscope.

[0084] XRD analysis was carried out using a Shimadzu XRD-6100 X-ray diffractometer with a Cu target under the given conditions.

[0085] Solid UV analysis was carried out using a Shimadzu UV3600 ultraviolet-visible-near-infrared spectrophotometer.

[0086] Raman spectroscopy analysis was carried out using a HORIBA LabRAM Soleil high-resolution, ultrasensitive, intelligent Raman imager.

[0087] The calculation methods for conversion rate and selectivity in the examples of this application are as follows:

[0088] In the examples of this application, the propane conversion rate and propylene selectivity were calculated as follows:

[0089]

[0090]

[0091] Among them, [CH4], [C2H4], [C2H6], [C3H6], and [C3H8] are the concentrations of CH4, C2H4, C2H6, C3H6, and C3H8 in the product, respectively.

[0092] Example 1

[0093] Co x％ The synthesis ratio of the @yMo-S-1 (x = 0 to 0.88, y = 0 to 0.08) catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(MoO3) = 1:0.28:40:A:B (fix A at 0.001, B / A = 20 / 1, 40 / 1, 60 / 1, 80 / 1; fix B at 0.08, B / A = 80 / 1, 40 / 1, 13 / 1, 10 / 1, B or A not added), and the specific synthesis steps are as follows:

[0094] 1) Mix 9.11 g of TPAOH solution with 21.85 g of deionized water, stir at 25 °C for 1 hour, and dilute.

[0095] 2) Add 0.77 g of sodium molybdate dihydrate to the solution obtained in step 1), and stir at 25 °C for 1 hour (or add 0.19 g, 0.39 g, 0.58 g, 0.77 g of sodium molybdate dihydrate respectively, corresponding to Mo / Co molar ratios of 20 / 1, 40 / 1, 60 / 1, 80 / 1).

[0096] 3) Dissolve 0.52 g of cobalt nitrate hexahydrate in 3 mL of deionized water, add 2 mL of ethylenediamine, stir for 3 hours, and make up to 10 mL to obtain a 0.18 M Co(NH2CH2CH2NH2)3(NO3)2 solution.

[0097] 4) Add the complex solution obtained in step 3) to the solution obtained in step 2), and the addition amounts are 0.25 mL, 0.5 mL, 1 mL, 2 mL respectively (corresponding to Mo / Co molar ratios of 80 / 1, 40 / 1 / , 13 / 1, 10 / 1), and continue to stir at 25 °C for 1 hour (or only add 0.25 mL, fixing the amount of cobalt).

[0098] 5) Add 8.32 g of TEOS to step 4), stir at 25 °C for 18 hours, and obtain a homogeneous mixture after complete hydrolysis of TEOS.

[0099] 6) Transfer the mixture solution obtained in step 5) to a stainless steel autoclave, then place the autoclave in an oven and crystallize at 90 °C for 48 hours; after the crystallization is completed, take out the autoclave, naturally cool it to room temperature, and then centrifuge the substances in the autoclave to separate out the solid product. Wash the solid product repeatedly with deionized water until it is neutral, and then dry it in an oven at 80 °C to obtain Cox％ @0.08 Mo-S-1 raw powder (or Co 0.11％ @y Mo-S-1 raw powder).

[0100] 7) Calcinate the 1 g sample Co x％ @0.08 Mo-S-1 (or Co 0.11％ @y Mo-S-1 raw powder) molecular sieve raw powder in a muffle furnace. Raise the temperature to 550 °C in 4 hours, then keep it at 550 °C for 6 h to obtain the calcined sample Co x％ @0.08 Mo-S-1-C (or Co 0.11％ @y Mo-S-1-C).

[0101] 8) Add the Co x％ @0.08 Mo-S-1-C obtained in step 7) to a 0.2 mol / L ammonium chloride solution and stir for 1 hour for ion exchange (the mass ratio of Co x％ @0.08 Mo-S-1-C to the ammonium chloride solution is 1:40). Centrifuge the ion-exchanged sample to separate the solid, then dry it in an oven at 60 °C - 90 °C, and then heat and calcine it in air. Raise the temperature to 550 °C in 4 hours, then keep it at 550 °C for 6 h to obtain the Co x％ @0.08 Mo-S-1-IE (ion exchange) sample (or Co 0.11％ @y Mo-S-1-IE).

[0102] 9) Repeat step 8) three times to obtain the Co x％ @0.08 Mo-S-1-IE catalyst, which are Co 0.11％ @0.08 Mo-S-1-IE catalyst, Co 0.22％ @0.08 Mo-S-1-IE catalyst, Co 0.44％ @0.08 Mo-S-1-IE catalyst, Co 0.88％ @0.08 Mo-S-1-IE catalyst, Co 0.11％ @0.02 Mo-S-1-IE catalyst, Co 0.11％ @0.04 Mo-S-1-IE catalyst, Co 0.11％ @0.06 Mo-S-1-IE catalyst, Co 0.11％ @S-1 catalyst, 0.08 Mo-S-1 catalyst.

[0103] Co x％ @y Mo-S-1-IE catalyst's XRD pattern is as Figure 1 shown. It can be seen from the figure that the catalysts prepared in Example 1 all maintain a complete MFI topological structure.

[0104] Co 0.11％ The STEM electron microscope images of the 0.08Mo-S-1-IE catalyst are as follows Figure 2 shown. It can be seen from the figure that Co and Mo are very evenly dispersed on the molecular sieve. At high resolution, it can be seen from the bright spots circled by the circles that Co and Mo are in a monodispersed state, and the metal size is less than 0.3 nm. Figure 3 For Co 0.11％ @0.08Mo-S-1, the Raman spectrum shows that in the sample Mo / Co 0.11％ @S-1 impregnated with Mo, a signal peak at 973 cm -1 can be seen, which belongs to clusters or nanoparticles of molybdenum oxide. However, for Co 0.11％ @0.08Mo-S-1, this signal peak is not seen, indicating that Mo is well dispersed on the molecular sieve and has even been embedded in the framework of the molecular sieve.

[0105] Figure 4 The following are the UV spectra of different samples. It can be seen from the figure that before ion exchange, Co 0.11％ @0.08Mo-S-1 has very obvious peaks of tetracoordinated Co 2+ (535 nm, 588 nm, 636 nm). After ion exchange, the intensities of these peaks decrease sharply, indicating that the interaction between Mo and Co becomes stronger after ion exchange.

[0106] Example 2

[0107] Co x％ @yW-S-1 (x = 0 - 0.8, y = 0 - 0.06) catalyst synthesis ratio: SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:20:A:B (fix A as 0.002, B / A = 5 / 1, 10 / 1, 20 / 1, 30 / 1; fix B as 0.04, B / A = 40 / 1, 20 / 1, 10 / 1, 7 / 1, 5 / 1, no B or no A added). The specific synthesis steps are as follows:

[0108] 1) Mix 8.32 g of TEOS solution with 7.808 g of TPAOH solution and stir for 1 hour at 25 °C for dilution;

[0109] 2) Dissolve 0.53 g of sodium tungstate in 8.49 g of deionized water and stir for 1 hour at 25 °C (or add 0.13 g, 0.26 g, 0.53 g, 0.79 g of sodium tungstate respectively, corresponding to W / Co molar ratios of 5 / 1, 10 / 1, 20 / 1, 30 / 1);

[0110] 3) Dissolve 0.52 g of cobalt nitrate hexahydrate in 3 mL of deionized water, add 2 mL of ethylenediamine, stir for 3 hours, and make up the volume to 10 mL to obtain a 0.18 M Co(NH2CH2CH2NH2)3(NO3)2 solution.

[0111] 4) Add the metal salt solution obtained in step 2) to the solution obtained in step 1), and continue to stir at 25 °C for 1 hour.

[0112] 5) Add the complex solution obtained in step 3) to the solution obtained in step 4) in amounts of 0.23 mL, 0.46 mL, 0.92 mL, 1.38 mL, 1.84 mL (corresponding to W / Co molar ratios of 40 / 1, 20 / 1, 10 / 1, 7 / 1, 5 / 1), stir at 25 °C for 18 hours, and obtain a homogeneous mixture after complete hydrolysis of TEOS.

[0113] 6) Transfer the solution obtained in step 5) to a stainless-steel autoclave, then place the autoclave in an oven and crystallize it at a constant temperature of 90 °C for 48 hours; after the crystallization is completed, take out the autoclave, naturally cool it to room temperature, and then centrifuge the substances in the autoclave to separate out the solid product. Wash the solid product repeatedly with deionized water until it is neutral, and then dry it in an oven at 80 °C to obtain Co x％ @0.04W-S-1 raw powder (or Co 0.2％ @yW-S-1 raw powder).

[0114] 7) Calcinate 1 g of the sample Co x％ @0.04W-S-1 (or Co 0.2％ @yW-S-1 raw powder) molecular sieve raw powder in a muffle furnace, raise the temperature to 550 °C in 4 hours, and then keep it at 550 °C for 6 h to obtain Co x％ @0.04W-S-1-C (or Co 0.2％ @yW-S-1-C) calcined sample.

[0115] 8) Add the Co x％ @0.04W-S-1 obtained in step 7) to 0.2 M ammonium chloride solution and stir for 1 hour for ion exchange (the mass ratio of Co x％ @0.04W-S-1-C to ammonium chloride solution is 1:40), centrifuge the ion-exchanged sample to separate out the solid, then dry it in an oven at 60 °C - 90 °C, and then heat and calcine it in air, raise the temperature to 550 °C in 4 hours, and then keep it at 550 °C for 6 h to obtain Co x％ @0.04W-S-11-IE (ion exchange) sample (or Co 0.2％ @yW-S-1-IE).

[0116] 9) Repeat step 8) three times to obtain Cox％ @0.04W-S-1-IE catalyst, respectively Co 0.1％ @0.04W-S-1-IE catalyst, Co 0.2％ @0.04W-S-1-IE catalyst, Co 0.4％ @0.04W-S-1-IE catalyst, Co 0.6％ @0.04W-S-1-IE catalyst, Co 0.8％ @0.04W-S-1-IE catalyst, Co 0.2％ @0.01W-S-1-IE catalyst, Co 0.2％ @0.02W-S-1-IE catalyst, Co 0.2％ @0.06W-S-1-IE catalyst, Co 0.2％ @S-1 catalyst, 0.04W-S-1 catalyst.

[0117] Co x％ @The XRD patterns of the yW-S-1-IE catalysts are as Figure 7 shown. It can be seen from the figure that the catalysts prepared in Example 2 all maintain a complete MFI topological structure.

[0118] Example 3

[0119] The propane dehydrogenation reaction of the catalyst was carried out in a quartz tube fixed-bed reactor with an inner diameter of 13 mm under a reaction pressure of 0.1 Mpa. Before the dehydrogenation reaction, 0.3 g of the catalyst (40 - 60 mesh) and 1.0 g of quartz sand were blended. Under a reaction temperature of 600 °C or 550 °C, it was reduced for 0.5 h under a pure H2 flow rate of 50 mL / min, and then a propane / nitrogen mixed gas with a propane volume fraction of 25% was added for the reaction. The flow rate of the mixed gas was 50 mL / min (C3H8 / N2 = 12.5 / 37.5 mL / min). Among them, Co x％ @The yMo-S-1-IE catalyst was the catalyst prepared in Example 1; Co x％ @The yW-S-1-IE catalyst was the catalyst prepared in Example 2.

[0120] Figure 5 The propane dehydrogenation reaction in Figure 5 -A and Figure 5 -C were the propane conversions of catalysts with different cobalt contents and different molybdenum contents at 600 °C; Figure 5 -B and Figure 5 -D were the propylene selectivities of catalysts with different cobalt contents and different molybdenum contents at 600 °C; Figure 6 -A and Figure 6 -B were at 550 °C, 4.5 h -1 under Co0.11％ Long-term stability test results of the PDH conversion of the 0.08Mo-S-1-IE catalyst. As can be seen from Figure 5 -A and Figure 5 -C, 0.08Mo-S-1 has almost no reactivity, and Co 0.11％ @S-1 also only has a propane conversion rate of 8.7%, and the propylene selectivity of both is less than 90%. However, the activity of Co 0.11％ @S-1 is higher than that of the impregnated Co 0.11％ / S-1 sample, indicating that reducing the size of Co helps to improve the reactivity.

[0121] After in-situ introducing Mo into the framework, an obvious synergistic effect occurs between Co and Mo. The initial propane conversion rate of Co 0.11％ @0.08Mo-S-1-IE reaches 39.5%, which is nearly 5 times higher than that of Co 0.11％ @S-1 (8.7%), and the propylene selectivity also reaches 97.2%, which is nearly 10 percentage points higher than that of Co 0.11％ @S-1 (87.5%). It is worth noting that in the low-temperature reaction at 550 °C, Co 0.11％ @0.08Mo-S-1-IE still maintains a propane conversion rate of more than 20%, while Co 0.11％ @S-1 only has a propane conversion rate of 2.1%, and the improvement is more than ten times, and its selectivity is even more than 99%, which can be comparable to traditional PtZn or PtSn catalysts. At 550 °C, in the 4.5h -1 long-term stability test, after 72 hours of on-line reaction, only 1% deactivation occurs, and the selectivity is above 99% throughout the process, and the propylene production rate reaches 30.59mol C3H6 g Co - 1 h -1 , exceeding the level of all reported cobalt-based propane dehydrogenation catalysts by an order of magnitude (see Table 1). (In the propane dehydrogenation process, except for the parameters involved in the table, other operations are the same as in Example 3)

[0122] Figure 8 The propane dehydrogenation reaction in Figure 8 -A and Figure 8 -B are the propane conversion rates of catalysts with different cobalt contents and different tungsten contents at 550 °C; Figure 8 -C and Figure 8 -D are the propylene selectivities of catalysts with different cobalt contents and different tungsten contents at 550 °C. As can be seen from Figure 8 -A and Figure 8 -B, 0.04W-S-1 has almost no reactivity, and Co0.2％ @The propane conversion rate of S-1 is only 2%, and the propylene selectivity of both is average. After in-situ introducing W on the framework, obvious synergistic effects occur between Co and W. Co 0.2％ @The initial propane conversion rate of 0.04W-S-1-IE reaches 18%, compared with Co 0.2％ @S-1(%), which is nearly 10 times higher, and the propylene selectivity also reaches an astonishing 98.5%. Compared with Co 0.2％ @S-1(96.5%), it is increased by nearly 2 percentage points, and the propylene production rate reaches 9.0 mol C3H6 g Co -1 h -1 , far exceeding all reported cobalt-based propane dehydrogenation catalysts (see Table 1). (In the propane dehydrogenation process, except for the parameters involved in the table, other operations are the same as in Example 3)

[0123] Table 1

[0124]

[0125] Among them, the citations in Table 1 are as follows:

[0126] Citation 1: W.Y. Wang, Y. Wu, T.Y. Liu, Y.F. Zhao, Y.T. Qu, R.O. Yang, Z.G. Xue, Z.Y. Wang, F.Y. Zhou, J.P. Long, Z.K. Yang, X. Han, Y. Lin, M. Chen, L.R. Zheng, H. Zhou, X.G. Lin, F. Wu, H.J. Wang, Y.H. Yang, Y.F. Li, Y.H. Dai and Y.E. Wu, Single Co Sites in Ordered SiO2 Channels for Boosting Nonoxidative Propane Dehydrogenation. ACS. Catal. 12, 2632 - 2638 (2022).

[0127] Citation 2: C. Chen, S. Zhang, Z. Wang and Z.-Y. Yuan, Ultrasmall Co confined in the silanols of dealuminated beta zeolite: A highly active and selective catalyst for direct dehydrogenation of propane to propylene, J Catal. 383, 77 - 87 (2020).

[0128] Citation 3: Y. Wang, Y. Suo, J.-T. Ren, Z. Wang and Z.-Y. Yuan, Spatially isolated cobalt oxide sites derived from MOFs for direct propane dehydrogenation, J Colloid Interf Sci. 594, 113 - 121 (2021).

[0129] Citation 4: S. Song, J. Li, Z. Wu, P. Zhang, Y. Sun, W. Song, Z. Li and J. Liu, In-Situ encapsulated subnanometric CoO clusters within silicalite-1 zeolite for efficient propane dehydrogenation, Aiche J. 68, e17451 (2021).

[0130] Citation 5: Z.P. Hu, G. Qin, J. Han, W. Zhang, N. Wang, Y. Zheng, Q. Jiang, T. Ji, Z.Y. Yuan, J. Xiao, Y. Wei and Z. Liu, Atomic Insight into the Local Structure and Microenvironment of Isolated Co-Motifs in MFI Zeolite Frameworks for Propane Dehydrogenation, J Am Chem Soc. 144, 12127 - 12137 (2022).

[0131] Citation 6: L. Wu, Z. Ren, Y. He, M. Yang, Y. Yu, Y. Liu, L. Tan and Y. Tang, Atomically Dispersed Co(2+) Sites Incorporated into a Silicalite-1 Zeolite Framework as a High-Performance and Coking-Resistant Catalyst for Propane Nonoxidative Dehydrogenation to Propylene, ACS Appl Mater Interfaces. 13, 48934 - 48948 (2021).

[0132] Citation 7: Y. Gao, L. Peng, J. Long, Y. Wu, Y. Dai and Y. Yang, Hydrogen pre–reduction determined Co–silica interaction and performance of cobalt catalysts for propane dehydrogenation, Micropor Mesopor Mat. 323, 111187 (2021).

[0133] Example 4

[0134] In this example, Co was synthesized using other raw materials 0.11％ The ratio of the @0.08Mo - S - 1 - IE catalyst was SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(MoO3) = 1:0.28:40:0.001:0.08, and the specific synthesis steps were as follows:

[0135] 1) Mix 9.11 g of TPAOH solution with 21.85 g of deionized water, stir at 25 °C for 1 hour, and dilute.

[0136] 2) Add 0.77 g of sodium molybdate dihydrate to the solution obtained in step 1), and stir at 25 °C for 1 hour.

[0137] 3) Dissolve 0.52 g of cobalt nitrate hexahydrate in 3 mL of deionized water, add 2 mL of ethylenediamine, stir for 3 hours, and make up the volume to 10 mL to obtain a 0.18 M Co(NH2CH2CH2NH2)3(NO3)2 solution.

[0138] 4) Add the complex solution obtained in step 3) to the solution obtained in step 2) in an amount of 0.25 mL, and continue to stir at 25 °C for 1 hour.

[0139] 5) Add 2.40 g of silica white, and stir at 25 °C for 2 hours to obtain a homogeneous mixture.

[0140] 6) Transfer the solution obtained in step 5) to a stainless-steel autoclave, then place the autoclave in an oven and crystallize at a constant temperature of 90 °C for 48 hours; after the crystallization is completed, take out the autoclave, naturally cool it to room temperature, and then centrifuge the substances in the autoclave to separate out the solid product. Wash the solid product repeatedly with deionized water until it is neutral, and then dry it in an oven at 80 °C to obtain Co 0.11％ @0.08Mo-S-1 raw powder.

[0141] 7) Calcinate 1 g of the sample Co 0.11％ @0.08Mo-S-1 molecular sieve raw powder in a muffle furnace, raise the temperature to 550 °C in 4 hours, and then hold at 550 °C for 6 h to obtain Co 0.11％ @0.08Mo-S-1-C calcined sample.

[0142] 8) Add the Co 0.11％ @0.08Mo-S-1-C obtained in step 7) to a 0.2 mol / L ammonium chloride solution and stir for 1 hour for ion exchange (the mass ratio of Co 0.11％ @0.08Mo-S-1-C to the ammonium chloride solution is 1:40), centrifuge the ion-exchanged sample to separate out the solid, then dry it in an oven at 60 - 90 °C, and then heat and calcine it in air, raise the temperature to 550 °C in 4 hours, and then hold at 550 °C for 6 h to obtain Co 0.11％ @0.08Mo-S-1-IE (ion exchange) sample.

[0143] 9) Repeat step 8) three times to obtain Co 0.11％ @0.08Mo-S-1-IE catalyst.

[0144] The synthesized Co 0.11％ @0.08Mo-S-1-IE catalyst is also carried out in a quartz tube fixed-bed reactor with an inner diameter of 13 mm under a reaction pressure of 0.1 Mpa. Before the dehydrogenation reaction, blend 0.3 g of the catalyst (40 - 60 mesh) and 1.0 g of quartz sand, and reduce it under a pure H2 flow rate of 50 mL / min at a reaction temperature of 525 °C for 0.5 h, and then add a propane / nitrogen mixed gas with a propane volume fraction of 25% for reaction. The flow rate of the mixed gas is 50 mL / min (C3H8 / N2 = 12.5 / 37.5 mL / min). The reaction space velocity is 4.5 h -1 。

[0145] Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE still has a propane conversion rate of 12.9%, and the propylene selectivity reaches 99.4%. The results show that under low-temperature conditions, Co 0.11％ @0.08Mo-S-1-IE still maintains a high propane conversion rate and propylene selectivity, and its performance is very excellent.

[0146] Example 5

[0147] In this example, the synthesis method of the Co 0.11％ @0.08Mo-S-1-IE catalyst is similar to that of Example 4, and the difference lies in:

[0148] In step 1), 9.11 g of TPAOH solution is mixed with 18.25 g of deionized water.

[0149] In step 5), 6.00 g of silica sol (40 wt%) is added and stirred at 25 °C for 2 hours.

[0150] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 4, and the difference lies in: reacting at a temperature of 575 °C.

[0151] Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE has an initial propane conversion rate of 26.1%, and the propylene selectivity reaches 98.3%. The results show that under the conditions of 575 °C, Co 0.11％ @0.08Mo-S-1-IE still maintains a high propane conversion rate and propylene selectivity, and its performance remains very stable.

[0152] Example 6

[0153] In this example, the synthesis method of the Co 0.11％ @0.08Mo-S-1-IE catalyst is similar to that of Example 4, and the difference lies in:

[0154] In step 1), 9.11 g of TPAOH solution is mixed with 21.49 g of deionized water.

[0155] In step 5), 11.37 g of sodium silicate nonahydrate is added and stirred at 25 °C for 2 hours.

[0156] In step 6), the constant-temperature crystallization temperature is 80 °C.

[0157] In step 7), the calcination conditions are: heating to 600 °C in 4 hours, and then holding at 600 °C for 6 h.

[0158] The conditions for heating and calcining in step 8) are as follows: the temperature is raised to 600 °C in 4 hours, and then held at 600 °C for 6 hours.

[0159] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 4, except that: a. The reaction is carried out at a temperature of 550 °C. b. The flow rate of the mixed gas is 16.6 mL / min (C3H8 / N2 = 4.1 / 12.5 mL / min), and the reaction space velocity is 1.5 h -1 .

[0160] Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE has an initial propane conversion rate of 32.1%, and the propylene selectivity reaches 98.1%. The results show that at 550 °C and a space velocity of 1.5 h -1 under the space velocity condition, Co 0.11％ @0.08Mo-S-1-IE exhibits a higher propane conversion rate and stability, and its performance is very excellent.

[0161] Example 7

[0162] In this example, the synthesis method of the Co 0.11％ @0.08Mo-S-1-IE catalyst is similar to that in Example 4, except that:

[0163] In step 3), 0.43 g of cobalt chloride hexahydrate is dissolved in 3 mL of deionized water.

[0164] In step 5), 8.32 g of tetraethyl orthosilicate is added and stirred at 25 °C for 18 hours.

[0165] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 4, except that: a. The reaction is carried out at a temperature of 550 °C. b. The flow rate of the mixed gas is 33.3 mL / min (C3H8 / N2 = 8.3 / 25 mL / min), and the reaction space velocity is 3 h -1 .

[0166] Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE has an initial propane conversion rate of 26.3%, and the propylene selectivity is higher than 98%. The results show that at 550 °C and a space velocity of 3 h -1 under the space velocity condition, Co 0.11％ @0.08Mo-S-1-IE still maintains a relatively high propane conversion rate and propylene selectivity, and its performance is very excellent.

[0167] Example 8

[0168] In this example, the synthesis method of the Co 0.11％ @0.08Mo-S-1-IE catalyst is similar to that in Example 4, except that:

[0169] In step 3), 0.28 g of cobalt sulfate is dissolved in 3 mL of deionized water.

[0170] In step 5), 8.32 g of tetraethyl orthosilicate is added and stirred at 25 °C for 18 hours.

[0171] The calcination conditions in the muffle furnace in step 7) are as follows: heating to 600 °C in 4 hours, and then holding at 600 °C for 6 h.

[0172] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 4, except that the reaction is carried out at a temperature of 550 °C.

[0173] Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE has an initial propane conversion rate higher than 18%, and the propylene selectivity reaches 99%. The results show that at 550 °C and a space velocity of 4.5 h -1 under the condition, Co 0.11％ @0.08Mo-S-1-IE undergoes an online reaction for 24 h without obvious deactivation, and the conversion rate increases.

[0174] Example 9

[0175] In this example, the synthesis method of the Co 0.11％ @0.08Mo-S-1-IE catalyst is similar to that in Example 4, except that:

[0176] In step 3), 0.45 g of cobalt acetate tetrahydrate is dissolved in 3 mL of deionized water.

[0177] In step 5), 8.32 g of tetraethyl orthosilicate is added and stirred at 25 °C for 18 hours.

[0178] The calcination conditions in the muffle furnace in step 7) are as follows: heating to 575 °C in 4 hours, and then holding at 575 °C for 6 h.

[0179] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 4, except that the reaction is carried out at a temperature of 550 °C.

[0180] Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE has an initial propane conversion rate exceeding 20%, and the propylene selectivity reaches more than 95%. The results show that at 550 °C and a space velocity of 4.5 h -1 under the condition, Co 0.11％ @0.08Mo-S-1-IE still does not show a cliff-like decrease in activity after 5 calcination-reduction cycles, indicating that its cycle stability is very good.

[0181] Example 10

[0182] In this example, Co 0.11％ The synthesis method of the @0.08Mo-S-1-IE catalyst is similar to that of Example 4, except that:

[0183] In step 2), 0.76 g of potassium molybdate is added to the solution obtained in step 1).

[0184] In step 3), 0.52 g of cobalt nitrate hexahydrate is dissolved in 3 mL of deionized water.

[0185] In step 5), 8.32 g of tetraethyl orthosilicate is added and stirred at 25 °C for 18 hours.

[0186] The conditions for constant-temperature crystallization in step 6) are: constant-temperature crystallization at 110 °C for 36 hours;

[0187] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 4, except that:

[0188] At a reaction temperature of 550 °C, it is reduced under a pure H2 flow of 50 mL / min for 0.5 h, and then a propane / nitrogen mixed gas with a propane volume fraction of 50% is added for reaction. The flow rate of the mixed gas is 25 mL / min (C3H8 / N2 = 12.5 / 12.5 mLmin -1 ).

[0189] Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE has an initial propane conversion rate of more than 15%, and the propylene selectivity reaches more than 95%. The results show that at 550 °C and a space velocity of 4.5 h -1 conditions, Co 0.11％ @0.08Mo-S-1-IE still has good activity in an atmosphere with a relatively high propane concentration.

[0190] Example 11

[0191] In this example, Co 0.11％ The synthesis method of the @0.08Mo-S-1-IE catalyst is similar to that of Example 4, except that:

[0192] The raw material ratio for synthesizing the Co 0.11％ @0.08Mo-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(MoO3) = 1:0.28:72:0.001:0.08.

[0193] In step (2), 0.56 g of ammonium molybdate tetrahydrate was added to a mixed solution of 10 mL of deionized water and 2 mL of ammonia water. After stirring for 30 min, 20 mL of 0.3 mol / L 2Na-EDTA solution was added. After stirring the mixed solution at 25 °C for 30 min, the solution obtained in step (1) was added, and the mixture was stirred at 25 °C for 1 hour.

[0194] In step (5), 8.32 g of tetraethyl orthosilicate was added and stirred at 25 °C for 18 hours.

[0195] The reaction conditions for propane dehydrogenation in this example were similar to those in Example 4, except that:

[0196] a. Before the dehydrogenation reaction, 0.1 g of the catalyst (40-60 mesh) and 1.2 g of quartz sand were blended and reacted at a temperature of 600 °C.

[0197] b. The flow rate of the mixed gas was 100 mL / min (C3H8 / N2 = 25 / 75 mL / min -1 ), and the reaction space velocity was 27 h -1 .

[0198] Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE, although only having an initial propane conversion rate of 9.8%, still had a propane conversion rate of 8.7% after 400 min of reaction, and the propylene selectivity reached 94%. The results showed that under the high space velocity conditions of 600 °C and 27 h -1 , Co 0.11％ @0.08Mo-S-1-IE still had high propylene selectivity and stability, and its performance was very excellent.

[0199] Example 12

[0200] In this example, the synthesis method of the Co 0.11％ @0.08Mo-S-1-IE catalyst was similar to that in Example 4, except that:

[0201] The raw material ratio for synthesizing the Co 0.11％ @0.08Mo-S-1-IE catalyst was SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NHCH2CH2NH2]2(NO3)2):B(MoO3) = 1:0.28:40:0.001:0.08.

[0202] In step (2), 0.76 g of potassium molybdate was added to the solution obtained in step (1).

[0203] In step 3), 0.52 g of cobalt nitrate hexahydrate was dissolved in 3 mL of deionized water, 2 mL of diethylenetriamine was added, and the mixture was stirred for 3 hours and then made up to 10 mL to obtain a 0.18 M solution of Co(NH2CH2CH2NHCH2CH2NH2)2(NO3)2.

[0204] In step 5), 8.32 g of tetraethyl orthosilicate was added and stirred at 25 °C for 18 hours.

[0205] In step 6), the conditions for isothermal crystallization were: isothermal crystallization at 120 °C for 36 hours.

[0206] In step 7), the conditions for calcination were: heating to 650 °C in 4 hours and holding at 650 °C for 6 h.

[0207] The reaction conditions for propane dehydrogenation in this example were similar to those in Example 4, except that:

[0208] a. Before the dehydrogenation reaction, 0.05 g of the catalyst (40 - 60 mesh) and 1.25 g of quartz sand were mixed and reacted at a temperature of 550 °C.

[0209] b. The flow rate of the mixed gas was 100 mL / min (C3H8 / N2 = 25 / 75 mL / min -1 ), and the reaction space velocity was 54 h -1 .

[0210] Under these reaction conditions, Co 0.11％ @0.08Mo - S - 1 - IE, although only having a propane conversion rate of 6.1%, still had an acrylene selectivity of over 90%. The results showed that under the space velocity conditions of 600 °C and 54 h -1 , Co 0.11％ @0.08Mo - S - 1 - IE still maintained a relatively high acrylene selectivity and its performance was still good.

[0211] Example 13

[0212] In this example, the synthesis method of the Co 0.11％ @0.08Mo - S - 1 - IE catalyst was similar to that in Example 4, except that: the raw material ratio for synthesizing the Co 0.11％ @0.08Mo - S - 1 - IE catalyst was SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2](NO3)2):B(MoO3) = 1:0.28:40:0.001:0.08.

[0213] In step 2), 0.76 g of potassium molybdate was added to the solution obtained in step 1) and stirred at 25 °C for 1 hour.

[0214] In step 3), 0.52 g of cobalt nitrate hexahydrate was dissolved in 3 mL of deionized water, 2 mL of tetraethylenepentamine was added, and the mixture was stirred for 3 hours and made up to 10 mL to obtain a 0.18 M solution of Co(NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2)(NO3)2.

[0215] In step 5), 8.32 g of tetraethyl orthosilicate was added and stirred at 25 °C for 18 hours.

[0216] The calcination conditions in step 7) were as follows: heating to 700 °C in 4 hours and then holding at 700 °C for 6 h.

[0217] The reaction conditions for propane dehydrogenation in this example were similar to those in Example 4, except that the reaction was carried out at a temperature of 550 °C. Under these reaction conditions, Co 0.11％ @0.08Mo-S-1-IE had an initial propane conversion rate of 20%, and the propylene selectivity reached 99.0%. The results showed that under the space velocity conditions of 550 °C and 4.5 h -1 Co 0.11％ @0.08Mo-S-1-IE had a high propylene conversion rate comparable to that of traditional active catalysts and excellent performance.

[0218] Example 14

[0219] In this example, the synthesis method of the Co 0.11％ @0.08Mo-S-1-IE catalyst was similar to that in Example 4, except that the raw material ratio for synthesizing the Co 0.11％ @0.08Mo-S-1-IE catalyst was SiO2:TPAOH:H2O:A([Co-NH2CH2CH2(NHCH2CH2)2NH2](NO3)2):B(MoO3) = 1:0.28:40:0.001:0.08.

[0220] In step 2), 0.87 g of molybdenum pentachloride was added to the solution obtained in step 1) and stirred at 25 °C for 1 hour.

[0221] In step 3), 0.52 g of cobalt nitrate hexahydrate was dissolved in 3 mL of deionized water, 2 mL of triethylenetetramine was added, and the mixture was stirred for 3 hours and made up to 10 mL to obtain a 0.18 M solution of [Co-NH2CH2CH2(NHCH2CH2)2NH2](NO3)2.

[0222] In step 5), 8.32 g of tetraethyl orthosilicate was added and stirred at 25 °C for 18 hours.

[0223] The calcination conditions in step 7) were as follows: heating to 700 °C in 4 hours and then holding at 700 °C for 6 h.

[0224] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 4, with the difference being that the reaction is carried out at a temperature of 550 °C.

[0225] Under these reaction conditions, the propane conversion rate of Co 0.11％ @0.08Mo-S-1-IE can reach 22%, and the propylene selectivity exceeds 99%. The results show that under the space velocity conditions of 550 °C and 4.5 h -1 Co 0.11％ @0.08Mo-S-1-IE has a high propylene conversion rate comparable to that of traditional active catalysts, and its performance is very excellent.

[0226] Example 15

[0227] In this example, other raw materials were used to synthesize Co 0.2％ @0.04W-S-1-IE catalyst with a ratio of SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:20:0.002:0.04. The specific synthesis steps are as follows:

[0228] 1) Mix 2.40 g of silica white with 7.808 g of TPAOH solution, and stir at 25 °C for 1 hour for dilution;

[0229] 2) Dissolve 0.53 g of sodium tungstate in 8.49 g of deionized water, and stir at 25 °C for 1 hour;

[0230] 3) Dissolve 0.52 g of cobalt nitrate hexahydrate in 3 mL of deionized water, add 2 mL of ethylenediamine, stir for 3 hours, and make up the volume to 10 mL to obtain a 0.18 M Co(NH2CH2CH2NH2)3(NO3)2 solution.

[0231] 4) Add the metal salt solution obtained in step 2) to the solution obtained in step 1), and continue to stir at 25 °C for 1 hour.

[0232] 5) Add the complex solution obtained in step 3) to the solution obtained in step 4), with an addition amount of 0.46 mL, stir at 25 °C for 18 hours, and obtain a homogeneous mixture after complete hydrolysis of TEOS.

[0233] 6) Transfer the solution obtained in step 5) to a stainless steel autoclave, then place the autoclave in an oven and crystallize at a constant temperature of 90 °C for 48 hours; after the crystallization is completed, take out the autoclave, naturally cool it to room temperature, then centrifuge the substances in the autoclave to separate the solid product, wash the solid product repeatedly with deionized water until it is neutral, and then dry it in an oven at 80 °C to obtain Co 0.2％ @0.04W-S-1 original powder.

[0234] 7) Add 1 g of the sample Co obtained in step 6) 0.2％ @0.04W-S-1 zeolite powder was calcined in a muffle furnace. The temperature was raised to 550 °C in 4 hours, and then held at 550 °C for 6 h to obtain Co 0.2％ @0.04W-S-1-C calcined sample.

[0235] 8) Add the Co obtained in step 7) 0.2％ @0.04W-S-1-C to 0.2 M ammonium chloride solution and stir for 1 hour for ion exchange (the mass ratio of Co 0.2％ @0.04W-S-1-C to ammonium chloride solution is 1:40). Centrifuge the ion-exchanged sample to separate the solid, then dry it in an oven at 60 °C - 90 °C, and then heat and calcine it in air. The temperature is raised to 550 °C in 4 hours, and then held at 550 °C for 6 h to obtain Co 0.2％ @0.04W-S-1-IE (ion exchange) sample.

[0236] 9) Repeat step 8) three times to obtain Co 0.2％ @0.04W-S-1-IE catalyst.

[0237] The synthesized Co 0.2％ @0.04W-S-1-IE catalyst was also carried out in a quartz tube fixed-bed reactor with an inner diameter of 13 mm under a reaction pressure of 0.1 Mpa. Before the dehydrogenation reaction, 0.3 g of the catalyst (40 - 60 mesh) and 1.0 g of quartz sand were blended. At a reaction temperature of 550 °C, it was reduced under a pure H2 flow of 50 mL / min for 0.5 h, and then a propane / nitrogen mixed gas with a propane volume fraction of 25% was added for the reaction. The flow rate of the mixed gas was 50 mL / min (C3H8 / N2 = 12.5 / 37.5 ml min -1 ), and the reaction space velocity was 4.5 h -1 .

[0238] The results show that under these reaction conditions, Co 0.2％ @0.04W-S-1-IE still has a propane conversion rate of 14.9%, and the propylene selectivity reaches 98.1%. Co 0.2％ @0.04W-S-1-IE still maintains a relatively high propane conversion rate and propylene selectivity, and its performance is very excellent.

[0239] Example 16

[0240] In this example, the synthesis method of the Co 0.2％ @0.04W-S-1-IE catalyst is similar to that in Example 15, and the difference is that the synthesis of Co 0.2％The raw material ratio of the @0.04W-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0241] In step 1), 6.00 g of silica sol (40 wt%) was mixed with 7.808 g of TPAOH solution.

[0242] Under the same reaction conditions as in Example 15, Co 0.2％ @0.04W-S-1-IE has an initial propane conversion rate of 16.3% and a propylene selectivity of 97.5%. The results show that under the condition of 550 °C, Co 0.2％ @0.04W-S-1-IE still maintains a relatively high propane conversion rate and propylene selectivity, and its performance is still very stable.

[0243] Example 17

[0244] In this example, Co 0.2％ The synthesis method of the @0.04W-S-1-IE catalyst is similar to that of Example 15, except that: the synthesis of Co 0.2％ The raw material ratio of the @0.04W-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0245] In step 1), 11.37 g of sodium silicate nonahydrate was mixed with 7.808 g of TPAOH solution.

[0246] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 15, except that: the flow rate of the mixed gas is 16.6 mL / min (C3H8 / N2 = 4.1 / 12.5 mLmin -1 ), and the reaction space velocity is 1.5 h -1 .

[0247] Under these reaction conditions, Co0.2%@0.04W-S-1-IE has an initial propane conversion rate of 20.3% and a propylene selectivity of 98.4%. The results show that under the conditions of 550 °C and a space velocity of 1.5 h -1 , Co 0.2％ @0.04W-S-1-IE shows a higher propane conversion rate and stability, and its performance is excellent.

[0248] Example 18

[0249] In this example, Co 0.2％The synthesis method of the @0.04W-S-1-IE catalyst is similar to that of Example 15, with the difference that: the synthesis of Co 0.2％ The ratio of the @0.04W-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0250] In step 1), 8.32 g of tetraethyl orthosilicate is mixed with 7.808 g of TPAOH solution.

[0251] Under the same reaction conditions as in Example 15, Co 0.2％ @0.04W-S-1-IE has an initial propane conversion rate of 17.8%, and the propylene selectivity is higher than 97.8%. The results show that at 550 °C and a space velocity of 4.5 h -1 under the conditions, Co 0.2％ @0.04W-S-1-IE still maintains a high propane conversion rate and propylene selectivity, and its performance is very excellent.

[0252] Example 19

[0253] In this example, Co 0.2％ The synthesis method of the @0.04W-S-1-IE catalyst is similar to that of Example 15, with the difference that: the synthesis of Co 0.2％ The raw material ratio of the @0.04W-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0254] In step 1), 8.32 g of tetraethyl orthosilicate is mixed with 7.808 g of TPAOH solution.

[0255] In step 3), 0.45 g of cobalt acetate tetrahydrate is dissolved in 3 mL of deionized water, 2 mL of ethylenediamine is added, and stirred for 3 hours, and the volume is fixed to 10 mL to obtain a 0.18 M Co(NH2CH2CH2NH2)3(CH3COOH)2 solution.

[0256] Under the same reaction conditions as in Example 15, Co 0.2％ The initial propane conversion rate of @0.04W-S-1-IE is higher than 13%, and the propylene selectivity reaches 96%. The results show that at 550 °C and a space velocity of 4.5 h -1 under the conditions, Co 0.2％ @0.04W-S-1-IE undergoes an on-line reaction for 12 h, without obvious deactivation, and the conversion rate increases.

[0257] Example 20

[0258] In this example, Co 0.2％ The synthesis method of the @0.04W-S-1-IE catalyst is similar to that of Example 15, except that: when synthesizing Co 0.2％ The raw material ratio of the @0.04W-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0259] In step 1), 8.32 g of tetraethyl orthosilicate is mixed with 7.808 g of TPAOH solution.

[0260] In step 3), 0.28 g of cobalt sulfate is dissolved in 3 mL of deionized water, 2 mL of ethylenediamine is added, and stirred for 3 hours, then made up to 10 mL to obtain a 0.18 M Co(NH2CH2CH2NH2)3SO4 solution.

[0261] Under the same reaction conditions as in Example 15, Co 0.2％ The @0.04W-S-1-IE has an initial propane conversion rate of over 16%, and the propylene selectivity reaches over 94%. The results show that under the space velocity conditions of 550 °C and 4.5 h -1 for Co 0.2％ The @0.04W-S-1-IE still does not show a cliff-like decrease in activity after 5 calcination-reduction cycles, indicating that its cycle stability is very good.

[0262] Example 21

[0263] In this example, Co 0.2％ The synthesis method of the @0.04W-S-1-IE catalyst is similar to that of Example 15, except that: when synthesizing Co 0.2％ The raw material ratio of the @0.04W-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0264] In step 1), 8.32 g of tetraethyl orthosilicate is mixed with 7.808 g of TPAOH solution.

[0265] In step 2), 0.59 g of potassium tungstate is dissolved in 8.49 g of deionized water.

[0266] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 15, except that:

[0267] The flow rate of the mixed gas is 25 mL / min (C3H8 / N2 = 12.5 / 12.5 mL / min -1 ).

[0268] Under these reaction conditions, Co 0.2％ @0.04W-S-1-IE has an initial propane conversion rate of over 12%, and the propylene selectivity reaches over 93%. The results show that at 550 °C and a space velocity of 4.5 h -1 under the space velocity condition, Co 0.2％ @0.04W-S-1-IE still has good activity in an atmosphere with a relatively high propane concentration.

[0269] Example 22

[0270] The synthesis method of the Co 0.2％ @0.04W-S-1-IE catalyst in this example is similar to that in Example 15, except that: the raw material ratio for synthesizing the Co 0.2％ @0.04W-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0271] In step 1), 8.32 g of tetraethyl orthosilicate is mixed with 7.808 g of TPAOH solution.

[0272] In step 2), 0.46 g of ammonium tungstate is dissolved in 8.49 g of deionized water.

[0273] The reaction conditions for propane dehydrogenation in this example are similar to those in Example 15, except that:[[]]

[0274] a. Before the dehydrogenation reaction, 0.1 g of the catalyst (40 - 60 mesh) and 1.2 g of quartz sand are blended and reduced under a pure H2 flow rate of 50 mL / min at a reaction temperature of 600 °C for 0.5 h.

[0275] b. The flow rate of the mixed gas is 100 mL / min (C3H8 / N2 = 25 / 75 mL / min -1 ), and the reaction space velocity is 27 h -1 .

[0276] Under these reaction conditions, the initial propane conversion rate of Co 0.2％ @0.04W-S-1-IE reaches 7.3%, and the propylene selectivity reaches 94%. The results show that at 600 °C and a high space velocity of 27 h -1 under the space velocity condition, Co 0.2％ @0.04W-S-1-IE still has a certain propylene selectivity and stability, and its performance is very excellent.

[0277] Example 23

[0278] In this example, Co 0.2％ @0.04W-S-1-IE catalyst was synthesized in a similar way to that in Example 15, with the difference that: when synthesizing Co 0.2％ @0.04W-S-1-IE catalyst, the raw material ratio was SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0279] In step 1), 8.32 g of tetraethyl orthosilicate was mixed with 7.808 g of TPAOH solution.

[0280] In step 2), 0.52 g of potassium tungstate was dissolved in 8.49 g of deionized water.

[0281] The reaction conditions for propane dehydrogenation in this example were similar to those in Example 15, with the difference that:

[0282] a. Before the dehydrogenation reaction, 0.05 g of the catalyst (40 - 60 mesh) was blended with 1.25 g of quartz sand;

[0283] b. The flow rate of the mixed gas was 100 mL / min (C3H8 / N2 = 25 / 75 mLmin -1 ), and the reaction space velocity was 54 h -1 .

[0284] Under the reaction conditions, the initial propane conversion rate of Co 0.2％ @0.04W-S-1-IE was 5.3%, but its propylene selectivity could still reach over 92%. The results showed that under the space velocity condition of 550 °C and 4.5 h -1 , Co 0.2％ @0.04W-S-1-IE still maintained a high propylene selectivity and had excellent performance.

[0285] Example 24

[0286] In this example, Co 0.2％ @0.04W-S-1-IE catalyst was synthesized in a similar way to that in Example 15, with the difference that: when synthesizing Co 0.2％ @0.04W-S-1-IE catalyst, the raw material ratio was SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0287] In step 1), 8.32 g of tetraethyl orthosilicate was mixed with 7.808 g of TPAOH solution.

[0288] In step 2), 0.52 g of potassium tungstate is dissolved in 8.49 g of deionized water.

[0289] In step 3), 0.52 g of cobalt nitrate hexahydrate is dissolved in 3 mL of deionized water, 2 mL of tetraethylenepentamine is added, and the mixture is stirred for 3 hours and then made up to 10 mL to obtain a 0.18 M solution of Co(NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2)(NO3)2.

[0290] Under the same reaction conditions as in Example 15, Co 0.2％ @0.04W-S-1-IE has an initial propane conversion of 16% and a propylene selectivity of 94.6%. The results show that at 550 °C and a space velocity of 4.5 h -1 under the conditions, Co 0.2％ @0.04W-S-1-IE exhibits excellent catalytic performance and propylene selectivity.

[0291] Example 25

[0292] In this example, the synthesis method of the Co 0.2％ @0.04W-S-1-IE catalyst is similar to that in Example 15, except that: the raw material ratio for synthesizing the Co 0.2％ @0.04W-S-1-IE catalyst is SiO2:TPAOH:H2O:A(Co[NH2CH2CH2NH2]3(NO3)2):B(WO3) = 1:0.24:40:0.002:0.04.

[0293] In step 1), 8.32 g of tetraethyl orthosilicate is mixed with 7.808 g of TPAOH solution.

[0294] In step 2), 0.52 g of potassium tungstate is dissolved in 8.49 g of deionized water.

[0295] In step 3), 0.52 g of cobalt nitrate hexahydrate is dissolved in 3 mL of deionized water, 2 mL of triethylenetetramine is added, and the mixture is stirred for 3 hours and then made up to 10 mL to obtain a 0.18 M solution of [Co-NH2CH2CH2(NHCH2CH2)2NH2](NO3)2.

[0296] Under the same reaction conditions as in Example 15, Co 0.2％ @0.04W-S-1-IE can achieve a propane conversion of 13% and a propylene selectivity of over 96%. The results show that at 550 °C and a space velocity of 4.5 h -1 under the conditions, Co 0.2％ @0.04W-S-1-IE has excellent performance.

[0297] Comparative example

[0298] The preparation method of the catalyst in this comparative example is similar to that of Example 4, the difference being that: in step 8), ammonium chloride solution was not used for ion exchange.

[0299] The reaction conditions for propane dehydrogenation in this comparative example are the same as those in Example 4. The propane conversion rate of the catalyst prepared in this comparative example is 1.0%, and the propylene selectivity is 80.7%, specifically as Figure 9 shown.

[0300] Obviously, the above examples are merely illustrations for clear explanation and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A catalyst, characterized in that, The catalyst includes a support and an active component; The support is a pure silica molecular sieve substituted by an inactive element; The active element in the active component includes Co; wherein, Co is loaded in the support in a single-site structure; The Co exists in the catalyst in the forms of Co-O-Si, Co-O-inactive element and Co-O; wherein, the Co is connected to the support through Co-O-Si and Co-O-inactive element; the coordination number of Co-O is 3; the valence is +2; The inactive element includes Mo or W, and exists in the form of +6-valent Mo ions or W ions; The pure silica molecular sieve in the pure silica molecular sieve substituted by the inactive element is a Silicalite-1 molecular sieve; The loading amount of the active element in the catalyst is 0.1 wt% to 0.88 wt%.

2. The catalyst according to claim 1, characterized in that, The molar ratio of the inactive element to the active element is x, where 0 < x ≤ 80:

1.

3. A method for preparing the catalyst according to claim 1 or 2, characterized in that, It includes the following steps: (1) Mix a metal complex, a template agent, a silicon source and an inactive element source, and perform hydrothermal crystallization in water to obtain precursor I; (2) Calcinate the precursor I obtained in step (1) in air, add an ammonium salt for ion exchange, and then calcinate to obtain the catalyst; In step (1), the metal complex is selected from one or more of [T(NH2CH2CH2NH2)3]Cl2, [T(NH2CH2CH2NH2)3](NO3)2, [T(NH2CH2CH2NH2)3](OAc)2, [T(NH2CH2CH2NH2)3]SO4, [T(NH2CH2CH2NHCH2HCH2NH2)3]Cl2, [T(NH2CH2CH2NHCH2HCH2NH2)3](NO3)2, [T(NH2CH2CH2NHCH2HCH2NH2)3](OAc)2, [T(NH2CH2CH2NHCH2HCH2NH2)3]SO4, [T-NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2]Cl2, [T-NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2](NO3)2, [T-NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2](OAc)2, [T-NH2CH2CH2NHCH2CH2NHCH2CH2NHCH2CH2NH2]SO4, [T-NH2CH2CH2(NHCH2CH2)2NH2]Cl2, [T-NH2CH2CH2(NHCH2CH2)2NH2](NO3)2, [T-NH2CH2CH2(NHCH2CH2)2NH2](OAc)2, [T-NH2CH2CH2(NHCH2CH2)2NH2]SO4; wherein, T is the metal element in the metal complex; the T is Co.

4. The preparation method according to claim 3, characterized in that, In step (1), the template agent is selected from one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrabutylammonium hydroxide, and tetrabutylphosphonium hydroxide; the silicon source is selected from one or more of tetraethyl orthosilicate, fumed silica, silica sol, and sodium silicate; the non-active element source is selected from a molybdenum source or a tungsten source; the molybdenum source is selected from one or more of sodium molybdate, ammonium molybdate, potassium molybdate, molybdenum ethylenediaminetetraacetate, and molybdenum pentachloride; the tungsten source is selected from one or more of potassium tungstate, ammonium tungstate, sodium tungstate, and sodium phosphotungstate.

5. The preparation method according to claim 3, characterized in that, In step (1), one or more of the following conditions are satisfied: the molar ratio of the template agent to the silicon source is 0.24 - 0.4:1; the molar ratio of the metal complex to the silicon source is 0.001 - 0.008:1; the molar ratio of the non-active element source to the silicon source is 0.01 - 0.08:1; the molar ratio of water to the silicon source is 20 - 40:

1.

6. The preparation method according to claim 3, characterized in that, One or two of the following conditions are satisfied: the conditions for hydrothermal crystallization are: isothermal crystallization at 80°C - 120°C for 8 hours - 48 hours; the conditions for heating and calcination are: calcination at 500°C - 700°C for 4 hours - 8 hours.

7. A method for propane dehydrogenation, characterized in that, It includes the following steps: contacting a gas containing propane with a catalyst for reaction to carry out propane dehydrogenation; the catalyst is the catalyst described in claim 1 or 2 or the catalyst obtained by the preparation method described in any one of claims 3 - 6.

8. The method according to claim 7, characterized in that, One or more of the following conditions are satisfied: the volume content of propane in the gas containing propane is 25% - 100%; the gas flow rate is 15 mL / min - 100 mL / min; the gas containing propane includes nitrogen and / or hydrogen; the reaction temperature is 500°C - 600°C; the reaction pressure is 0.1 MPa - 0.2 MPa.

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