Catalyst for preparing propylene through propane dehydrogenation as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing propylene through propane dehydrogenation and a preparation method and application thereof, and belongs to the field of catalysis for preparing propylene through propane dehydrogenation. The preparation method comprises the following steps: mixing a template agent with water, adding precursors of an element B and an element C, then adding a silicon source, carrying out hydrothermal crystallization, washing, drying and roasting a product, and then mixing, stirring and roasting the product with a precursor of an element A; wherein the element A comprises at least one of Ru, Rh, Pd, Ir and Pt; the B element comprises at least one of B, Al, Ga and In; the C element comprises at least one of Li, Na, K, Rb and Cs; the catalyst comprises the following components in percentage by mass: 0.01-1% of an element A, 1-20% of an element B, 1-20% of an element C and the balance of an S-1 molecular sieve. The catalyst has the characteristics of high propane conversion rate, high product propylene selectivity, strong sintering resistance, good stability and the like. The preparation method of the catalyst is simple, raw materials are cheap and easy to obtain, and the catalyst has a good industrial prospect.

Description

Technical Field

[0001] This invention relates to the field of propane dehydrogenation to propylene catalysis, and more particularly to a catalyst for propane dehydrogenation to propylene, its preparation method, and its application. Background Technology

[0002] Propylene, as a key basic chemical raw material, has indispensable applications in many fields such as plastics, rubber, fibers, and pharmaceutical manufacturing. At present, about 10% of propylene is produced through propane dehydrogenation (PDH) technology. In particular, the shale gas revolution has brought a large amount of cheap propane, making PDH technology a highly anticipated development direction in the chemical industry.

[0003] The endothermic and high-temperature characteristics of the propane dehydrogenation to propylene reaction place stringent requirements on the catalyst. Existing catalysts, especially Pt-Sn or Cr-based catalysts supported on alumina, suffer from the following main problems: First, the active metal components are prone to sintering and agglomeration at high temperatures, leading to rapid catalyst deactivation; second, deep dehydrogenation and cracking side reactions easily occur on the catalyst surface, not only making it difficult to achieve propylene selectivity but also causing severe carbon deposition, resulting in a sharp decline in catalyst stability.

[0004] Therefore, the technical problem to be solved by the present invention is to provide a novel propane dehydrogenation catalyst and its preparation method, which aims to simultaneously achieve high activity, high propylene selectivity and excellent long-term stability of the catalyst, thereby overcoming the above-mentioned defects of the prior art. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems in the prior art and to provide a catalyst for the dehydrogenation of propane to propylene, its preparation method and application, which has the characteristics of high propane conversion, high propylene selectivity, strong anti-sintering ability and good stability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a catalyst for propane dehydrogenation to propylene includes the following steps:

[0008] 1) Mix the template agent with water to form a mixed solution;

[0009] 2) Add a precursor solution containing element B and a precursor solution containing element C to the mixed solution in step 1), then add a silicon source, stir evenly, and then perform hydrothermal crystallization; wash, dry and calcine the crystallized product to obtain CB@S-1;

[0010] 3) Mix the CB@S-1 obtained in step 2) with the precursor solution containing element A, and stir to form a suspension or paste;

[0011] 4) The suspension or paste obtained in step 3) is calcined, cooled, crushed, ground, and sieved to obtain the catalyst C-BA@S-1;

[0012] Wherein, element A includes at least one of Ru, Rh, Pd, Ir, and Pt; element B includes at least one of B, Al, Ga, and In; element C includes at least one of Li, Na, K, Rb, and Cs; by mass percentage, element A is 0.01% to 1%, element B is 1% to 20%, element C is 1% to 20%, and the balance is S-1 molecular sieve.

[0013] In step 1), the template agent is at least one of tetrapropylammonium hydroxide and tetraethylammonium hydroxide.

[0014] In step 2), the silicon source is selected from at least one of tetraethyl orthosilicate, silica sol, and silica.

[0015] In step 2), the hydrothermal crystallization temperature is 60~280℃ and the crystallization time is 24~120h.

[0016] In step 2), the calcination is carried out in air, nitrogen or an inert atmosphere, at a temperature of 270~650℃, and for a time of 1.5~5h.

[0017] In step 4), the calcination is carried out under nitrogen or an inert atmosphere, the calcination temperature is 200~1000℃, and the calcination time is 4~8h.

[0018] A propane dehydrogenation catalyst for propylene production is prepared using the method described in this invention.

[0019] The catalyst comprises elements A, B, C and S-1 molecular sieve, wherein by mass percentage, element A is 0.01% to 1%, element B is 1% to 20%, element C is 1% to 20%, and the balance is S-1 molecular sieve.

[0020] The application of the propane dehydrogenation to propylene catalyst in the propane dehydrogenation reaction.

[0021] The propane dehydrogenation reaction is carried out at a temperature of 350–650 °C, a pressure of 0.3–1.0 bar, and a weight hourly space velocity of 4–20 h⁻¹. -1 The reaction raw materials are propane or a mixture of propane and nitrogen, wherein the volume content of propane is not less than 45%.

[0022] Compared with existing technologies, the beneficial effects of the present invention are as follows: 1. The catalyst of the present invention confines active metal A and auxiliary elements B and C within the channels of an S-1 molecular sieve, forming a stable structure, inhibiting the sintering of active metal A, and significantly improving the catalyst's anti-sintering ability and stability. First, an S-1 molecular sieve containing elements B and C is prepared, which prevents the sintering of metal B during calcination. Subsequently, element A is further introduced, combining with B and C through impregnation and generating strong interactions, which can improve the dispersion of metal A, thereby enhancing the catalyst's activity.

[0023] 2. Using the catalyst and preparation method described in this invention, the active metals interact to highly disperse the components, which helps to improve catalytic activity; and the auxiliary metal C element modifies the active metal A component, adjusts its surface to a certain positive oxidation state, inhibits the reaction of propane undergoing deep dehydrogenation to generate carbon deposits, and improves propylene selectivity and catalyst stability.

[0024] 3. The catalyst support is S-1 molecular sieve with a crystal size of 40~100 nm. Its small size and short pores result in a short residence time for olefins, which can inhibit reactions such as oligomerization of olefin products and improve the selectivity of propylene.

[0025] 4. In the propane dehydrogenation reaction, the catalyst achieves a propane conversion rate close to the thermodynamic equilibrium conversion rate, a propylene selectivity of up to 98%, and good catalyst stability, with almost no change in catalytic performance after 500 hours of testing.

[0026] 5. The propane dehydrogenation to propylene catalyst provided by this invention has catalytic performance and catalyst stability that are far superior to those of existing industrial catalysts, and has potential for industrial application. Attached Figure Description

[0027] Figure 1 The image shows the XRD pattern of the K-InRh@S-1 catalyst prepared in Example 2 before the reaction.

[0028] Figure 2 The image shows an electron microscope image of the K-InRh@S-1 catalyst prepared in Example 2.

[0029] Figure 3 The graph shows the performance of the K-InRh@S-1 catalyst prepared in Example 2 after 500 h of reaction. Detailed Implementation

[0030] To make the technical problems, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] The catalyst preparation process described in this invention is as follows:

[0032] 1) Mix the template agent and deionized water, and stir until homogeneous to form a mixed solution; wherein the template agent is at least one of tetrapropylammonium hydroxide and tetraethylammonium hydroxide, the stirring time is 5 to 30 minutes, the temperature is 20 to 40℃; the mass ratio of template agent to water is 1:3.5 to 8;

[0033] 2) Add measured amounts of aqueous solutions of metal elements B and C to the mixed solution in step 1) and stir until homogeneous; wherein metal element B is selected from at least one inorganic salt and organic salt, and metal element C is selected from at least one oxide, hydroxide, inorganic salt, and organic salt; the mass concentration of the aqueous solution of metal element B is 0.01–10 mol / L, the concentration of the aqueous solution of metal element C is 0.05–10 mol / L, the stirring time is 2–30 h, and the temperature is 20–80 °C; the mass ratio of the aqueous solution of metal element B to the template agent is 1:2.5–6.5; the mass ratio of the aqueous solution of metal element C to the template agent is 1:50–150;

[0034] 3) Add a measured amount of silicon source solution to the mixed solution in step 2) and stir for a certain period of time; wherein the silicon source is at least one of tetraethyl orthosilicate, silica sol, and silica; the silicon source is SiO2, with a mass concentration of 2% to 40%, the stirring time is 2 to 30 hours, and the temperature is 20 to 50°C.

[0035] 4) The mixed solution obtained in step 3) is transferred to a hydrothermal synthesis reactor for hydrothermal crystallization to obtain a crystallized product. The obtained product is washed, dried, and calcined to obtain a molecular sieve containing B and C elements, denoted as CB@S-1. The hydrothermal crystallization temperature is 60–280℃, the crystallization time is 24–120 h, the drying temperature is 30–100℃, the calcination time is 1.5–5 h, the calcination temperature is 270–650℃, and the calcination atmosphere includes nitrogen, inert gas, or air.

[0036] 5) Weigh the molecular sieve CB@S-1 and the A metal element precursor solution obtained in step 4) in a certain proportion, place them in a beaker, and stir with a magnetic stirrer to make the liquid uniformly wet the solid particles to form a suspension or paste mixture; wherein the A metal element precursor solution is selected from at least one of inorganic salts and organic salts, the stirring temperature is 25~80℃, the stirring time is 1~6h, and the mass ratio of the A metal element precursor solution to the template agent is 1:200~650;

[0037] 6) Transfer the suspension from step 5) to a ceramic boat, place it in a tube furnace and calcine it under nitrogen. Finally, cool it to obtain a solid formed from the molten mixture. Crush, grind and sieve the solid to obtain a catalyst containing element A, denoted as C-BA@S-1 catalyst. The calcination temperature is 200~1000℃ and the calcination time is 4~8h.

[0038] This invention discloses a catalyst for the dehydrogenation of propane to propylene. The catalyst is used in the propane dehydrogenation reaction, wherein a molded catalyst is loaded into a reactor, and propane or a propane atmosphere containing nitrogen is introduced to carry out the propane dehydrogenation reaction. The reaction temperature is 350–650°C; the reactor is selected from at least one of a fixed bed, a fixed fluidized bed, a circulating fluidized bed, or a moving bed; the reaction pressure is 0.3–1.0 bar; and the weight hourly space velocity is 4–20 h⁻¹. -1 In the nitrogen-containing propane atmosphere, the volume content of propane is not less than 45%.

[0039] Example 1

[0040] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of gallium nitrate aqueous solution (1.0 mol / L), 1.532 mL of KOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and placed in a muffle furnace and calcined at 550 °C in air for 2 h to obtain a molecular sieve containing Ga and K. 1.0 g of molecular sieve containing Ga and K and 0.2597 mL of Rh precursor solution (the precursor solution is a mixed solution of rhodium trichloride hydrate and ethylenediamine monohydrate, with a Rh mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as K-GaRh@S-1 catalyst.

[0041] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0042] Example 2

[0043] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of indium nitrate aqueous solution (1.0 mol / L), 1.532 mL of KOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and calcined in a muffle furnace at 550 °C for 2 h in air to obtain a molecular sieve containing In and K. 1.0 g of molecular sieve containing In and K and 0.2597 mL of Rh precursor solution (the precursor solution is a mixed solution of rhodium trichloride hydrate and ethylenediamine monohydrate, with a Rh mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as K-InRh@S-1 catalyst.

[0044] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0045] Example 3

[0046] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 2.214 mL of aluminum nitrate aqueous solution (1.0 mol / L), 1.532 mL of KOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and calcined in a muffle furnace at 550 °C for 2 h in air to obtain a molecular sieve containing Al and K. 1.0 g of molecular sieve containing Al and K and 0.2597 mL of Rh precursor solution (the precursor solution is a mixed solution of rhodium trichloride hydrate and ethylenediamine monohydrate, with a Rh mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as K-AlRh@S-1 catalyst.

[0047] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0048] Example 4

[0049] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of indium nitrate aqueous solution (1.0 mol / L), 1.532 mL of KOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and calcined in a muffle furnace at 550 °C for 2 h in air to obtain a molecular sieve containing In and K. 1.0 g of molecular sieve containing In and K and 0.2597 mL of Pd precursor solution (the precursor solution is a mixed solution of palladium nitrate and ethylenediamine monohydrate, with a Pd mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as K-InPd@S-1 catalyst.

[0050] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0051] Example 5

[0052] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of indium nitrate aqueous solution (1.0 mol / L), 1.532 mL of NaOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and calcined in a muffle furnace at 550 °C for 2 h in air to obtain a molecular sieve containing In and Na. 1.0 g of molecular sieve containing In and Na and 0.2597 mL of Pd precursor solution (the precursor solution is a mixed solution of palladium nitrate and ethylenediamine monohydrate, with a Pd mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as Na-InPd@S-1 catalyst.

[0053] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0054] Example 6

[0055] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of indium nitrate aqueous solution (1.0 mol / L), 1.532 mL of NaOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and calcined in a muffle furnace at 550 °C for 2 h in air to obtain a molecular sieve containing In and Na. 1.0 g of molecular sieve containing In and Na and 0.2597 mL of Rh precursor solution (the precursor solution is a mixed solution of rhodium trichloride hydrate and ethylenediamine monohydrate, with a Rh mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as Na-InRh@S-1 catalyst.

[0056] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0057] Example 7

[0058] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of indium nitrate aqueous solution (1.0 mol / L), 1.532 mL of KOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and calcined in a muffle furnace at 550 °C for 2 h in air to obtain a molecular sieve containing In and K. 1.0 g of molecular sieve containing In and K and 0.2597 mL of Pt precursor solution (the precursor solution is a mixed solution of chloroplatinic acid and ethylenediamine monohydrate, with a Pt mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as K-InPt@S-1 catalyst.

[0059] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0060] Example 8

[0061] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of gallium nitrate aqueous solution (1.0 mol / L), 1.532 mL of KOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and placed in a muffle furnace and calcined at 550 °C in air for 2 h to obtain a molecular sieve containing Ga and K. 1.0 g of molecular sieve containing Ga and K and 0.2597 mL of Pt precursor solution (the precursor solution is a mixed solution of chloroplatinic acid and ethylenediamine monohydrate, with a Pt mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as K-GaPt@S-1 catalyst.

[0062] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0063] Comparative Example 1

[0064] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of indium nitrate aqueous solution (1.0 mol / L) and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially and stirred at 25 °C for 10 min. The mixture was placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and placed in a muffle furnace and calcined at 550 °C in air for 2 h to obtain an In-containing molecular sieve. 1.0 g of In-containing molecular sieve and 0.2597 mL of Rh precursor solution (the precursor solution is a mixed solution of rhodium trichloride hydrate and ethylenediamine monohydrate, with an Rh mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as InRh@S-1 catalyst.

[0065] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0066] Comparative Example 2

[0067] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.532 mL of KOH aqueous solution (0.15 mol / L) and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially and stirred at 25 °C for 10 min. The mixture was placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and calcined in a muffle furnace at 550 °C for 2 h in air to obtain a K-containing molecular sieve. 1.0 g of K-containing molecular sieve and 0.2597 mL of Rh precursor solution (the precursor solution is a mixed solution of rhodium trichloride hydrate and ethylenediamine monohydrate, with a Rh mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was transferred to a ceramic boat and calcined in a tube furnace at 650 °C for 6 h under a nitrogen atmosphere. The cooled solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as K-Rh@S-1 catalyst.

[0068] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0069] Comparative Example 3

[0070] 7.778 g of deionized water and 1.667 g of tetrapropylammonium hydroxide (50% by mass, containing 20% ​​methanol) were added to a 100 mL beaker and stirred at 25 °C for 10 min. Then, 1.742 mL of indium nitrate aqueous solution (1.0 mol / L), 1.532 mL of KOH aqueous solution (0.15 mol / L), and 3.47 g of tetraethyl orthosilicate solution (SiO2 content 28.4%) were added sequentially, and the mixture was stirred at 25 °C for 10 min. The mixture was then placed in a 100 mL hydrothermal reactor and crystallized in an oven at 180 °C for 72 h. After natural cooling, the solid-liquid mixture in the reactor was centrifuged and dried at 80 °C for 4 h. The solid was then ground and placed in a muffle furnace and calcined at 550 °C in air for 2 h to obtain a molecular sieve containing In and K. 1.0 g of molecular sieve containing In and K and 0.2597 mL of Rh precursor solution (the precursor solution is a mixed solution of rhodium trichloride hydrate and ethylenediamine monohydrate, with a Rh mass fraction of 0.0154 g / mL) were placed in a 50 mL beaker. Deionized water was added dropwise while magnetically stirring at 40 °C until the mixture became a suspension. The mixture was then stirred for another 4 h. The resulting suspension was dried in an oven at 100 °C. The dried solid was crushed, ground, and sieved to obtain a 30-60 mesh catalyst, denoted as K-In / Rh@S-1 catalyst.

[0071] 0.2 g of the above-mentioned catalyst (30-60 mesh) was packed into a fixed-bed quartz reaction tube under atmospheric pressure. Then, the reaction raw materials gas was introduced. The reaction gases were propane and nitrogen (propane flow rate was 13.6 mL / min, nitrogen flow rate was 13.6 mL / min), and the reaction temperature was 580℃. The performance of the catalyst is shown in Table 1.

[0072] Table 1

[0073]

[0074] Depend on Figure 1 It can be seen that the characteristic diffraction peaks of S-1 molecular sieve appear in the X-ray diffraction pattern of K-InRh@S-1 catalyst, indicating that S-1 molecular sieve was successfully synthesized; however, no diffraction signals of In, K or Rh metals appear in the spectrum, indicating that there are no agglomerated metal particles on the catalyst surface. This is because the amount of In, K and Rh metals added is small, and the metals are highly dispersed inside the molecular sieve with small particle size.

[0075] Figure 2 The image shows a scanning electron microscope (SEM) image of the K-InRh@S-1 catalyst. It can be seen that the crystal size of the molecular sieve is about 100 nm. In addition, there are no obvious metal particles on the outer surface of the molecular sieve, which suggests that most of the active metal has entered the interior of the molecular sieve.

[0076] Figure 3 The graph shows the long-term stability of the K-InRh@S-1 catalyst in Example 2 (where the red line represents the conversion rate and the blue line represents the selectivity). Within 500 hours, the catalyst can maintain a high propane conversion rate of 39.6% and the propylene selectivity of 98.1% remains almost unchanged, which shows that the performance of this catalyst is extremely stable.

Claims

1. A method for producing a catalyst for dehydrogenation of propane to propylene, characterized by, The method comprises the following steps: 1) mixing a template agent with water to form a mixed solution; 2) adding a B element-containing precursor solution and a C element-containing precursor solution to the mixed solution of step 1), and then adding a silicon source, and hydrothermally crystallizing after uniform stirring; washing, drying and calcining the crystallized product to obtain C-B@S-1; 3) mixing the C-B@S-1 obtained in step 2) with an A element-containing precursor solution to form a suspension or paste after stirring; 4) calcining the suspension or paste obtained in step 3), and obtaining the catalyst C-BA@S-1 after cooling, crushing, grinding and sieving; wherein the A element comprises at least one of Ru, Rh, Pd, Ir and Pt; the B element comprises at least one of B, Al, Ga and In; the C element comprises at least one of Li, Na, K, Rb and Cs; the A element accounts for 0.01% to 1% by mass, the B element accounts for 1% to 20% by mass, the C element accounts for 1% to 20% by mass, and the balance is S-1 molecular sieve.

2. The method for preparing a propane dehydrogenation catalyst to propylene as described in claim 1, characterized in that: In step 1), the template agent is at least one of tetrapropylammonium hydroxide and tetraethylammonium hydroxide.

3. The process for preparing a catalyst for dehydrogenation of propane to propylene according to claim 1, characterized in that: In step 2), the silicon source is at least one of tetraethyl orthosilicate, silica sol and white carbon black.

4. The process for preparing a catalyst for dehydrogenation of propane to propylene according to claim 1, characterized in that: In step 2), the hydrothermal crystallization temperature is 60-280°C, and the crystallization time is 24-120h.

5. The process for preparing a catalyst for dehydrogenation of propane to propylene according to claim 1, characterized by: In step 2), the calcination is performed in air, nitrogen or inert atmosphere, the calcination temperature is 270-650°C, and the calcination time is 1.5-5h.

6. The process for preparing a catalyst for dehydrogenation of propane to propylene according to claim 1, characterized in that: In step 4), the calcination is performed in nitrogen or inert atmosphere, the calcination temperature is 200-1000°C, and the calcination time is 4-8h.

7. A catalyst for the dehydrogenation of propane to propylene, characterized in that: The catalyst is prepared by the method of any one of claims 1-6.

8. A catalyst for the dehydrogenation of propane to propylene according to claim 7, characterized in that: The catalyst comprises the A element, the B element, the C element and the S-1 molecular sieve, the A element accounts for 0.01% to 1% by mass, the B element accounts for 1% to 20% by mass, the C element accounts for 1% to 20% by mass, and the balance is S-1 molecular sieve.

9. The use of the propane dehydrogenation to propylene catalyst of any one of claims 7-8 in a propane dehydrogenation reaction.

10. Use according to claim 9, wherein: The reaction temperature of the propane dehydrogenation reaction is 350-650°C; and the reaction raw material is propane or a mixture of propane and nitrogen, wherein the volume content of propane is not less than 45%.

Images