Platinum-based molecular sieve catalyst for propane dehydrogenation as well as preparation method and application of platinum-based molecular sieve catalyst

Abstract

The invention discloses a platinum-based molecular sieve catalyst for propane dehydrogenation and a preparation method and application thereof. The method comprises the following steps: uniformly mixing a silicon source, a metal salt complex, alkali metal salt, a template agent and water, and removing ethanol; then, crystallizing the solution through a micro-channel reactor to obtain the platinum-based molecular sieve catalyst; the platinum-based molecular sieve catalyst provided by the invention is used in a propane dehydrogenation reaction, and the catalyst has good propane conversion rate and propylene selectivity; the method is realized through the micro-channel reactor, is safe, short in reaction time and stable and reliable in process, the whole reaction process is simple in procedure operation, the reaction process is controllable, and continuous production of the platinum-based molecular sieve catalyst is realized.

Description

Technical Field

[0001] The present invention relates to the field of petrochemical industry. Specifically, it relates to a platinum-based molecular sieve catalyst for propane dehydrogenation, and the present invention also relates to a preparation method and application of the catalyst. Background Art

[0002] Propylene is one of the most important basic chemical raw materials, and can be used to synthesize polypropylene, propylene oxide, propylene glycol, polyurethane, polyols, etc. In recent years, the large-scale and successful exploitation of natural gas and shale gas has promoted the development of industrial technologies for catalytic selective direct dehydrogenation of propane to propylene. Compared with other propylene production methods, the propane dehydrogenation method has outstanding advantages such as ultra-high propylene selectivity, no by-products, low cost, and rich production. Platinum-based catalysts have better carbon-hydrogen bond activation ability compared with chromium-based catalysts, and are more environmentally friendly. Platinum-based and chromium-based catalysts have been widely used in industrial production. In the process of producing propylene, the direct dehydrogenation of propane using chromium-based or platinum-based catalysts has become a very promising means to meet the growing demand for propylene.

[0003] The commonly used preparation methods for platinum-based molecular sieve catalysts are as follows:

[0004] 1. Post-synthesis method: Molecular sieves are usually synthesized by template-assisted hydrothermal crystallization. After removing the template by high-temperature calcination, the metal is introduced into the pores / cages of the molecular sieve by post-synthesis methods (ion exchange method, impregnation method, etc.) to obtain a platinum-based molecular sieve catalyst.

[0005] 2. In-situ synthesis method: The silicon source, template, metal species, etc. of the molecular sieve are directly constructed into a platinum-based catalyst supported on the molecular sieve by one-step hydrothermal method.

[0006] However, both of the above two preparation methods require a large amount of time, and the preparation process cannot be continuous. Based on this, a method for preparing a platinum-based molecular sieve catalyst with a short preparation time, stable and reliable process, simple operation, and continuous preparation is developed, hoping to solve the deficiencies in the prior art. Summary of the Invention

[0007] In order to overcome the deficiencies of the prior art, the present invention provides a preparation method of a platinum-based molecular sieve catalyst, which prepares the platinum-based molecular sieve catalyst through a microchannel reactor. This method has the characteristics of safety, short preparation time, stable and reliable process, simple operation, and continuity. At the same time, the catalyst has good propane conversion rate and propylene selectivity.

[0008] Therefore, the first technical solution provided by the present invention is as follows:

[0009] A preparation method of a platinum-based molecular sieve catalyst for propane dehydrogenation, successively comprising the following steps:

[0010] (1) Stir the platinum-based complex and aqueous tetrapropylammonium hydroxide evenly to obtain a mixed solution A;

[0011] (2) Add two kinds of promoter metal complexes, alkali metal, and tetraethyl orthosilicate to the mixed solution A in step (1), stir at room temperature for 0.5 - 2 h, and then raise the temperature to 60 - 100 °C and stir for 1 - 2 h to obtain a mixed solution B;

[0012] (3) Inject the mixed solution B in step (2) into a microchannel reactor through a feed pump, and crystallize in the capillary of the microchannel reactor at 150 - 170 °C to obtain a suspension;

[0013] (4) After the reaction is completed, centrifuge, dry, and calcine the suspension in step (1) at high temperature to obtain a platinum-based molecular sieve catalyst.

[0014] A preparation method of a platinum-based molecular sieve catalyst for propane dehydrogenation, successively including the following steps:

[0015] (1) Add a platinum salt to an aqueous solution of a ligand, stir until clear to obtain a platinum-based complex;

[0016] The molar ratio of the platinum salt to the ligand is 1:2

[0017] (2) Add a first promoter metal salt to water, then add a ligand and stir for 10 - 50 min for complexation to obtain a first promoter metal complex;

[0018] The molar ratio of the first promoter metal salt to the ligand is 1:1

[0019] (3) Add a second promoter metal salt to water, then add a ligand and stir for 10 - 50 min for complexation to obtain a second promoter metal complex;

[0020] The molar ratio of the second promoter metal salt to the ligand is 1:1

[0021] (4) Add a tetrapropylammonium hydroxide solution to water, and then add the platinum-based complex prepared in step (1), and stir for 20 - 40 min;

[0022] (5) Add the first promoter metal complex prepared in step (2) and the second promoter metal complex prepared in step (3), an alkali metal salt to the solution in step (4), and finally add tetraethyl orthosilicate, stir at room temperature for 1 h, and stir at 80 °C for 100 min to obtain a solution;

[0023] The molar ratio of tetrapropylammonium hydroxide, alkali metal salt, and tetraethyl orthosilicate is = 0.4:0.02:1

[0024] (6) Pump the solution in step (5) into the microchannel reactor through a feed pump, and crystallize it in the capillary of the microchannel reactor at 150 - 170 °C to obtain a suspension;

[0025] (7) After the reaction is completed, centrifuge, dry, and calcine the suspension in step (6) successively to obtain a platinum-based molecular sieve catalyst.

[0026] Further, in the above method for preparing a platinum-based molecular sieve catalyst, it is characterized in that the platinum salt in step (1) is one of platinum dichloride, chloroplatinic acid, tetraammineplatinum nitrate, and platinum nitrate.

[0027] Further, in the above method for preparing a platinum-based molecular sieve catalyst, it is characterized in that the aqueous solution of the ligand in step (1) has a volume concentration of 5% - 15%, and the ligand is one of ammonia water, diethylenetriamine, sodium ethylenediaminetetraacetate, tetraethylenepentamine, and ethylenediamine.

[0028] Further, in the above method for preparing a platinum-based molecular sieve catalyst, it is characterized in that the first promoter metal salt in step (2) is one of copper salt, zinc salt, tin salt, gallium salt, indium salt, manganese salt, cobalt salt, and iron salt; the second promoter metal salt in step (3) is one of copper salt, zinc salt, tin salt, gallium salt, indium salt, manganese salt, cobalt salt, and iron salt, and is different from the first promoter salt.

[0029] Further, in the above method for preparing a platinum-based molecular sieve catalyst, it is characterized in that the alkali metal in step (5) is one of potassium, sodium, lithium, and rubidium.

[0030] Further, in the above method for preparing a platinum-based molecular sieve catalyst, it is characterized in that the flow rate of the feed pump in step (6) is controlled at 0.7 - 1.5 mL / min, the residence time is 24 - 32 min, and the pressure during the process is 0.5 - 1 MPa.

[0031] Further, in the above method for preparing a platinum-based molecular sieve catalyst, it is characterized in that the centrifugation parameters in step (7) are 8000 r / min and the time is 2 - 4 min; the washing condition is washing with deionized water 3 - 5 times; the drying temperature is 60 °C and the time is 6 - 10 h, and the calcination temperature is 600 °C and the time is 6 h.

[0032] The second technical solution provided by the present invention is catalyzed by the platinum-based molecular sieve catalyst prepared by the above method.

[0033] The method for using this catalyst to catalyze propane dehydrogenation involves loading a platinum-based molecular sieve catalyst into a quartz glass reaction tube with an inner diameter of 7 mm, introducing hydrogen and nitrogen with a volume ratio of 1:19, then heating to 500 - 600 °C for 1 - 2 hours for reduction treatment, and then introducing propane and nitrogen with a volume ratio of 1:3 for reaction for 1 - 20 hours.

[0034] The platinum-based molecular sieve catalyst provided by the present invention is applied in the field of high-temperature thermal catalysis. The catalyst has a certain catalytic efficacy for light alkanes.

[0035] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:

[0036] (1) The technical solution provided by the present invention prepares a platinum-based molecular sieve catalyst through a microchannel reactor. This method is safe, has a short preparation time, stable and reliable process, simple operation, and can be continuously produced. At the same time, the catalyst has good propane conversion and propylene selectivity.

[0037] (2) The catalyst prepared by the microchannel has a low platinum loading, effectively reducing the preparation cost of the catalyst. Prepared by a one-step method, the catalyst preparation process is simple and has good industrial application prospects.

[0038] (3) The platinum-based molecular sieve catalyst prepared by the microchannel has a large specific surface area, which is beneficial to improving the catalyst activity and enhancing the catalytic performance. Description of the Drawings

[0039] Figure 1 It is the XRD diagram of the platinum-based molecular sieve catalyst;

[0040] Figure 2 It is the SEM diagram of the 0.2Pt0.5Cu0.3InK@S-1 catalyst;

[0041] Figure 3 It is the propane dehydrogenation activity diagram of the platinum-based molecular sieve catalyst; Detailed Embodiments

[0042] The following further illustrates the present invention with reference to the embodiments, but the protection scope of the present invention is not limited to the scope represented by the embodiments.

[0043] Embodiment 1

[0044] A method for preparing a platinum-based molecular sieve catalyst for propane dehydrogenation provided in this embodiment successively includes the following steps:

[0045] (1) Add 0.0098 g of platinum nitrate to 5 mL of an aqueous solution containing 0.04 mL of ethylenediamine, stir until clear to obtain a platinum-based complex;

[0046] (2) Add 0.057 g of copper nitrate trihydrate to 2.5 mL of an aqueous solution containing 0.05 mL of disodium ethylenediaminetetraacetate dihydrate, and stir for 30 min;

[0047] (3) Add 0.0157 g of indium nitrate tetrahydrate to 2.5 mL of an aqueous solution containing 0.02 mL of disodium ethylenediaminetetraacetate dihydrate, and stir for 30 min;

[0048] (4) Add 9.9 g of tetrapropylammonium hydroxide (40 wt% aqueous solution) to 15.5 mL of water, add the platinum complex prepared in step (1), and stir at 600 rpm for half an hour;

[0049] (5) Add the promoter metal complex prepared in step (2) and step (3) and 74 mg of potassium chloride to the solution in step (4), and finally add 10.425 g of tetraethyl orthosilicate, stir at room temperature for 1 h, and stir at 80 °C for 100 min;

[0050] (6) Pump the solution in step (5) into a microchannel reactor at a flow rate of 0.785 mL / min, with a residence time of 30 min, and crystallize in a capillary at 150 °C to obtain a suspension;

[0051] (7) After the reaction is completed, centrifuge the suspension in step (6) with centrifugation parameters of 8000 r / min for 4 min, wash 3 times with deionized water, and finally dry in a blast dryer at 60 °C for 6 h, and calcine in an air atmosphere at 600 °C for 6 h. The obtained sample is denoted as 0.2Pt0.5Cu0.2InK@S-1. The XRD pattern of this catalyst is shown in Figure 1 .

[0052] Example 2

[0053] A method for preparing a platinum-based molecular sieve catalyst for propane dehydrogenation provided in this example successively includes the following steps:

[0054] (1) Add 0.0098 g of platinum nitrate to 5 mL of an aqueous solution containing 0.04 mL of ethylenediamine, and stir until clear to obtain a platinum-based complex;

[0055] (2) Add 0.057 g of copper nitrate trihydrate to 2.5 mL of an aqueous solution containing 0.05 mL of disodium ethylenediaminetetraacetate dihydrate, and stir for 30 min;

[0056] (3) Add 0.0236 g of indium nitrate tetrahydrate to 2.5 mL of an aqueous solution containing 0.03 mL of disodium ethylenediaminetetraacetate dihydrate, and stir for 30 min;

[0057] (4) Add 9.9 g of tetrapropylammonium hydroxide (40 wt% aqueous solution) to 15.5 mL of water, add the platinum complex prepared in step (1), and stir for half an hour at 600 rpm;

[0058] (5) Add the promoter metal complex prepared in step (2) and step (3) and 74 mg of potassium chloride to the solution in step (4), and finally add 10.425 g of tetraethyl orthosilicate, stir at room temperature for 1 h, and stir at 80 °C for 100 min;

[0059] (6) Pump the solution in step (5) into a microchannel reactor at a flow rate of 0.785 mL / min, with a residence time of 30 min, and crystallize in the capillary at 150 °C to obtain a suspension;

[0060] (7) After the reaction is completed, centrifuge the suspension in step (6) with a centrifuge parameter of 8000 r / min for 4 min, wash it 3 times with deionized water, and finally dry it in a blast dryer at 60 °C for 6 h, and calcine it at 600 °C in an air atmosphere for 6 h. The obtained sample is denoted as 0.2Pt0.5Cu0.3InK@S-1. The XRD pattern of this catalyst is referred to Figure 1 , and the SEM image is referred to Figure 2 .

[0061] Example 3

[0062] A method for preparing a platinum-based molecular sieve catalyst for propane dehydrogenation provided in this example comprises the following steps in sequence:

[0063] (1) Add 0.0098 g of platinum nitrate to 5 mL of aqueous solution containing 0.04 mL of ethylenediamine, and stir until it becomes clear to obtain a platinum-based complex;

[0064] (2) Add 0.057 g of copper nitrate trihydrate to 2.5 mL of aqueous solution containing 0.05 mL of disodium ethylenediaminetetraacetate dihydrate, and stir for 30 min;

[0065] (3) Add 0.0315 g of indium nitrate tetrahydrate to 2.5 mL of aqueous solution containing 0.04 mL of disodium ethylenediaminetetraacetate dihydrate, and stir for 30 min;

[0066] (4) Add 9.9 g of tetrapropylammonium hydroxide (40 wt% aqueous solution) to 15.5 mL of water, add the platinum complex prepared in step (1), and stir for half an hour at 600 rpm;

[0067] (5) Add the promoter metal complex prepared in step (2) and step (3) and 74 mg of potassium chloride to the solution in step (4), and finally add 10.425 g of tetraethyl orthosilicate, stir at room temperature for 1 h, and stir at 80 °C for 100 min;

[0068] (6) The solution in step (5) was pumped into a microchannel reactor at a flow rate of 0.785 mL / min, with a residence time of 30 min, and crystallized in a capillary at 150 °C to obtain a suspension;

[0069] (7) After the reaction was completed, the suspension in step (6) was centrifuged with centrifugation parameters of 8000 r / min for 4 min, washed 3 times with deionized water, and finally dried in a blast dryer at 60 °C for 6 h and calcined at 600 °C in an air atmosphere for 6 h. The obtained sample was denoted as 0.2Pt0.5Cu0.4InK@S-1. The XRD pattern of this catalyst is shown in Figure 1 .

[0070] Comparative Example 1

[0071] A method for preparing a platinum-based molecular sieve catalyst for propane dehydrogenation provided in this example includes the following steps in sequence:

[0072] (1) 0.0098 g of platinum nitrate was added to 5 mL of an aqueous solution containing 0.04 mL of ethylenediamine and stirred until clear to obtain a platinum-based complex;

[0073] (2) 9.9 g of tetrapropylammonium hydroxide (40 wt% aqueous solution) was added to 20.5 mL of water, and the platinum complex prepared in step (1) was added, and stirred at 600 rpm for half an hour;

[0074] (3) 74 mg of potassium chloride was added to the solution in step (2), and finally 10.425 g of tetraethyl orthosilicate was added, and stirred at room temperature for 1 h and at 80 °C for 100 min;

[0075] (4) The solution in step (3) was pumped into a microchannel reactor at a flow rate of 0.785 mL / min, with a residence time of 30 min, and crystallized in a capillary at 150 °C to obtain a suspension;

[0076] (5) After the reaction was completed, the suspension in step (4) was centrifuged with centrifugation parameters of 8000 r / min for 4 min, washed 3 times with deionized water, and finally dried in a blast dryer at 60 °C for 6 h and calcined at 600 °C in an air atmosphere for 6 h. The obtained sample was denoted as 0.2PtK@S-1. The XRD pattern of this catalyst is shown in Figure 1 .

[0077] Comparative Example 2

[0078] A method for preparing a platinum-based molecular sieve catalyst for propane dehydrogenation provided in this example includes the following steps in sequence: (1) 0.0098 g of platinum nitrate was added to 5 mL of an aqueous solution containing 0.04 mL of ethylenediamine and stirred until clear to obtain a platinum-based complex;

[0079] (2) 0.057 g of copper nitrate trihydrate was added to 5 mL of an aqueous solution containing 0.05 mL of disodium ethylenediaminetetraacetate dihydrate, and the mixture was stirred for 30 min;

[0080] (3) 9.9 g of tetrapropylammonium hydroxide (40 wt% aqueous solution) was added to 15.5 mL of water, and the platinum complex prepared in step (1) was added. The mixture was stirred at 600 rpm for half an hour;

[0081] (4) The promoter metal complex prepared in step (2) and 74 mg of potassium chloride were added to the solution in step (3). Finally, 10.425 g of tetraethyl orthosilicate was added, and the mixture was stirred at room temperature for 1 h and at 80 °C for 100 min;

[0082] (5) The solution in step (4) was pumped into a microchannel reactor at a flow rate of 0.785 mL / min, with a residence time of 30 min. Crystallization occurred in the capillary at 150 °C to obtain a suspension;

[0083] (6) After the reaction was completed, the suspension in step (5) was centrifuged at 8000 rpm for 4 min, washed 3 times with deionized water, and finally dried in a blast dryer at 60 °C for 6 h and calcined at 600 °C in an air atmosphere for 6 h. The obtained sample was designated as 0.2Pt0.5CuK@S-1. The XRD pattern of this catalyst is shown in Figure 1 .

[0084] Comparative Example 3

[0085] A method for preparing a platinum-based molecular sieve catalyst for propane dehydrogenation provided in this example comprises the following steps in sequence: (1) 0.0098 g of platinum nitrate was added to 5 mL of an aqueous solution containing 0.04 mL of ethylenediamine, and the mixture was stirred until clear to obtain a platinum complex;

[0086] (2) 0.0236 g of indium nitrate tetrahydrate was added to 5 mL of an aqueous solution containing 0.03 mL of disodium ethylenediaminetetraacetate dihydrate, and the mixture was stirred for 30 min;

[0087] (3) 9.9 g of tetrapropylammonium hydroxide (40 wt% aqueous solution) was added to 15.5 mL of water, and the platinum complex prepared in step (1) was added. The mixture was stirred at 600 rpm for half an hour;

[0088] (4) The promoter metal complex prepared in step (2) and 74 mg of potassium chloride were added to the solution in step (3). Finally, 10.425 g of tetraethyl orthosilicate was added, and the mixture was stirred at room temperature for 1 h and at 80 °C for 100 min;

[0089] (5) Pump the solution in step (4) into the microchannel reactor at a flow rate of 0.785 mL / min, with a residence time of 30 min, and crystallize in the capillary at 150 °C to obtain a suspension;

[0090] (6) After the reaction is completed, centrifuge the suspension in step (5) with centrifugation parameters of 8000 r / min for 4 min, wash it 3 times with deionized water, and finally dry it in a blast dryer at 60 °C for 6 h, and calcine it at 600 °C in an air atmosphere for 6 h. The obtained sample is denoted as 0.2Pt0.3InK@S-1. The XRD pattern of this catalyst is referred to Figure 1 .

[0091] Comparative Example 4

[0092] A preparation method of a platinum-based molecular sieve catalyst for propane dehydrogenation provided in this example successively includes the following steps:

[0093] Add 15.5 g of deionized water to the 50 mL PTFE reactor liner containing 9.9 g of tetrapropylammonium hydroxide (40 wt% aqueous solution), and then stir at 600 rpm for 30 minutes; (2) Dropwise add 10.425 g of tetraethyl orthosilicate solution and continue stirring for 1 h until complete hydrolysis; (3) Place the 50 mL PTFE reactor into a stainless steel reactor and crystallize statically at 170 °C for 3 days. (4) Centrifuge the solid in step (3) with centrifugation parameters of 8000 r / min for 4 min, wash it 3 times with deionized water, and finally dry it in a blast dryer at 60 °C for 6 h, and calcine it at 600 °C in an air atmosphere for 6 h. The obtained sample is denoted as S-1; (5) Add 0.0098 g of platinum nitrate to 5 mL of aqueous solution containing 0.04 mL of ethylenediamine and stir until clear to obtain a platinum-based complex; (6) Add 0.057 g of copper nitrate trihydrate and 0.0236 g of indium nitrate tetrahydrate to 10 mL of aqueous solution containing 0.08 mL of disodium ethylenediaminetetraacetate dihydrate and stir for 30 min; (7) Mix the solutions prepared in steps (5) and (6) and add 3 g of S-1 molecular sieve and stir for 6 h; (8) Dry it overnight at 70 °C and calcine it at 600 °C in an air atmosphere for 6 h. The obtained sample is denoted as 0.2Pt0.5Cu0.3InK / S-1. The XRD pattern of this catalyst is referred to Figure 1 .

[0094] It can be seen through Figure 2 that the prepared catalyst has typical MFI structure characteristic peaks (PDF#45-0737). After introducing platinum, metal promoters, and alkali metals, the intensity of the characteristic peaks does not decrease significantly, confirming that introducing metal species into the all-silica molecular sieve does not affect the crystallization process of the molecular sieve. No peaks belonging to metal species or their oxides are found in the XRD pattern, confirming that the metal species are well distributed in the molecular sieve.

[0095] pass Figure 3 It can be seen that the prepared 0.2Pt0.5Cu0.3InK@S-1 catalyst has uniform particle size and almost no metal oxides or metal particles on the surface, indicating that the metal species are not simply loaded on the outer surface of the all-silicon molecular sieve, but are encapsulated in the zeolite micropores, fixed in the zeolite mesopores, or the metal species are introduced into the all-silicon zeolite framework, thereby making the catalyst activity and stability even better.

[0096] Application Example 1

[0097] The platinum-based molecular sieve catalyst 0.2Pt0.5Cu0.2InK@S-1 prepared in Example 1 was applied to propane dehydrogenation reaction, and the specific method was as follows:

[0098] Weigh 200 mg of the catalyst 0.2Pt0.5Cu0.2InK@S-1 prepared in Example 1 and mix it with 200 mg of quartz sand and place it in a quartz tube supporting the fixed bed. -1 The reaction was carried out under the conditions of , and the gas after the reaction was monitored in real time by gas chromatography to analyze the propane conversion rate, propylene selectivity and deactivation rate. The specific data are shown in Table 2. Figure 1 Performance diagram for propane dehydrogenation.

[0099] Catalyst activity is expressed in terms of propane conversion, propylene selectivity and deactivation rate.

[0100] and the inactivation rate are calculated as follows

[0101]

[0102] A i Represents the relative content of substance i at the outlet; Con intial and Con fianal represent the conversion rates measured at the beginning and end of the experiment, t represents the reaction time (h), k d is the inactivation rate constant (h -1 )

[0103] Application Examples 2-3

[0104] Application Examples 2 to 3 provide the catalysts prepared in Examples 2 to 3 for use in propane dehydrogenation reactions. The specific methods, steps, and parameters are the same as those in Application Example 1. The difference lies in the specific types of catalysts used. For details, see Table 2.

[0105] Comparative Application Examples 1 to 4

[0106] Comparative Application Examples 1 to 4 provide the application of the catalysts prepared in Application Examples 1 to 3 to the propane dehydrogenation reaction. The specific methods, steps, parameters are the same as those in Application Example 1, and the difference lies in the specific types of catalysts used. See Table 1 for details.

[0107] Table 1

[0108] Application Example Catalyst Used Catalyst Dosage (mg) Reaction Temperature Space Velocity Application Example 1 0.2Pt0.5Cu0.2InK@S-1 200 550℃ <![CDATA[2.7h -1 > Application Example 2 0.2Pt0.5Cu0.3InK@S-1 200 550℃ <![CDATA[2.7h -1 > Application Example 3 0.2Pt0.5Cu0.4InK@S-1 200 550℃ <![CDATA[2.7h -1 > Comparative Application Example 1 0.2PtK@S-1 200 550℃ <![CDATA[2.7h -1 > Comparative Application Example 2 0.2Pt0.5CuK@S-1 200 550℃ <![CDATA[2.7h -1 > Comparative Application Example 3 0.2Pt0.3InK@S-1 200 550℃ <![CDATA[2.7h -1 > Comparative Application Example 4 0.2Pt0.5Cu0.3InK / S-1 200 550℃ <![CDATA[2.7h -1 >

[0109] Table 2

[0110] Application Example Catalyst Conversion Rate / % Selectivity / % <![CDATA[Deactivation rate / h -1 > Application Example 1 0.2Pt0.5Cu0.2InK@S-1 60.02～39.34 95.39～97.24 0.04 Application Example 2 0.2Pt0.5Cu0.3InK@S-1 51.79～47.15 97.18～97.68 0.0089 Application Example 3 0.2Pt0.5Cu0.4InK@S-1 63.28～38.43 93.54～97.1l 0.025 Comparative Application Example 1 0.2PtK@S-1 19.18～3.5 90.93～74.24 0.0894 Comparative Application Example 2 0.2Pt0.5CuK@S-1 48.8～13.56 94.42～93.46 0.0859 Comparative Application Example 3 0.2Pt0.3InK@S-1 49.33～43.27 96.98～97.42 0.0116 Comparative Application Example 4 0.2Pt0.5Cu0.3InK / S-1 26.74～8.95 94.99～85.81 0.0625

[0111] From Table 2 and Figure 3 it can be seen that the catalyst 0.2Pt0.5Cu0.2InK@S-1 in Application Example 1 exhibits a relatively high conversion rate and selectivity range (60.02% - 39.34% and 95.39% - 97.24%), and at the same time, the deactivation rate is relatively low

[0112] (0.04 h -1 ). In contrast, the catalyst 0.2PtK@S-1 in Comparative Application Example 1 has a lower conversion rate and selectivity range (19.18% - 3.5% and 90.93% - 74.24%), and a higher deactivation rate (0.0894 h -1 ). This indicates that the catalyst combination containing copper and indium elements can significantly improve the conversion rate and selectivity of the propane dehydrogenation reaction and reduce the deactivation rate of the catalyst.

[0113] Similarly, the catalysts in Application Examples 2 to 3 also exhibit catalytic performance superior to that of the corresponding comparative application examples. Especially the catalyst 0.2Pt0.5Cu0.3InK@S-1 in Application Example 2, although its conversion rate and selectivity range are slightly lower than those in Application Example 1, its deactivation rate is even lower (0.0089 h -1 ), showing better stability. The catalyst in Comparative Application Example 4, on the other hand, exhibits a lower conversion rate and selectivity and a higher deactivation rate. This indicates that compared with the catalysts prepared by the impregnation method, the catalysts prepared by the in-situ microchannel method can significantly improve the conversion rate and selectivity of the propane dehydrogenation reaction and reduce the deactivation rate of the catalyst.

[0114] In summary, by comparing the catalytic performance of Comparative Application Examples 1 to 3 with that of Application Examples 1 to 4, it can be concluded that the platinum-based molecular sieve catalyst of the present invention has excellent catalytic performance for the propane dehydrogenation reaction. In particular, the catalyst combination containing specific proportions of platinum, copper, indium, and potassium elements can significantly improve the conversion rate and selectivity of the reaction and reduce the deactivation rate of the catalyst. This provides strong technical support for the industrial application of the propane dehydrogenation reaction.

Claims

1. A method for preparing a platinum-based molecular sieve catalyst for propane dehydrogenation, characterized in that: The steps are as follows: (1) stirring a platinum complex and a tetrapropylammonium hydroxide aqueous solution to obtain a mixed solution; (2) adding two different auxiliary metal complexes, alkali metals and tetraethyl orthosilicate to the mixed solution of step (1), stirring at room temperature for 0.5 to 2 hours, and then heating to 60 to 100° C. and stirring for 1 to 2 hours to obtain a mixed solution B; (3) injecting the mixed solution B in step (2) into the microchannel reactor through a feed pump, and crystallizing at 150-170° C. in the capillary of the microchannel reactor to obtain a suspension; (4) After the reaction is completed, the suspension in step (1) is centrifuged, dried, and calcined at high temperature to obtain a platinum-based molecular sieve catalyst.

2. The method for preparing a platinum-based molecular sieve catalyst for propane dehydrogenation according to claim 1, characterized in that: The steps are as follows: (1) adding a platinum salt to an aqueous solution of a ligand and stirring until the solution is clear to obtain a platinum-based complex; The molar ratio of the platinum salt to the ligand is 1:2 (2) adding the first auxiliary metal salt to water, and then adding the ligand and stirring for 10 to 50 minutes for complexation to obtain the first auxiliary metal complex; The molar ratio of the first auxiliary metal salt to the ligand is 1:1; (3) adding the second auxiliary metal salt to water, and then adding the ligand and stirring for 10 to 50 minutes for complexation to obtain the second auxiliary metal complex; The molar ratio of the second auxiliary metal salt to the ligand is 1:1; (4) adding tetrapropylammonium hydroxide into water, and then adding the platinum complex prepared in step (1), and stirring for 20 to 40 minutes; (5) adding the first auxiliary metal complex prepared in step (2) and the second auxiliary metal complex prepared in step (3) and an alkali metal salt to the solution in step (4), and finally adding tetraethyl orthosilicate, stirring at room temperature for 1 hour and stirring at 80° C. for 100 minutes to obtain a solution; The molar ratio of tetrapropylammonium hydroxide, alkali metal salt and tetraethyl orthosilicate is 0.4:0.02:1; (6) pumping the solution in step (5) into the microchannel reactor through a feed pump, and crystallizing at 150-170° C. in the capillary of the microchannel reactor to obtain a suspension; (7) After the reaction is completed, the suspension in step (6) is centrifuged, dried, and calcined at high temperature in sequence to obtain a platinum-based molecular sieve catalyst.

3. The method for preparing a platinum-based molecular sieve catalyst according to claim 2, characterized in that: The platinum salt described in step (1) is one of platinum dichloride, chloroplatinic acid, tetraammine platinum nitrate and platinum nitrate.

4. The method for preparing a platinum-based molecular sieve catalyst according to claim 2, characterized in that: The ligand aqueous solution in step (1) has a volume concentration of 5% to 15%; the ligand is one of ammonia water, diethylenetriamine, sodium salt of ethylenediaminetetraacetic acid, tetraethylenepentamine, and ethylenediamine.

5. The method for preparing a platinum-based molecular sieve catalyst according to claim 2, characterized in that: The first auxiliary metal salt described in step (2) is one of copper salt, zinc salt, tin salt, gallium salt, indium salt, manganese salt, cobalt salt, and iron salt; the second auxiliary metal salt described in step (3) is one of copper salt, zinc salt, tin salt, gallium salt, indium salt, manganese salt, cobalt salt, and iron salt, and is different from the first auxiliary metal salt; the alkali metal described in step (5) is one of potassium, sodium, lithium, and rubidium.

6. The method for preparing a platinum-based molecular sieve catalyst according to claim 2, characterized in that: The flow rate of the feed pump in step (6) is controlled at 0.7-1.5 mL / min, the residence time is 24-32 min, and the pressure during the process is 0.5-1 MPa.

7. The method for preparing a platinum-based molecular sieve catalyst according to claim 2, characterized in that: In step (7), the centrifugal parameters are 8000 r / min and the time is 2 to 4 min; the washing conditions are 3 to 5 times of deionized water washing; the drying temperature is 60° C. and the time is 6 to 10 h; and the calcination temperature is 500 to 700° C. and the time is 4 to 8 h.

8. A platinum-based molecular sieve catalyst, characterized in that: The method according to claim 1 or 2 is used to prepare the product.

9. The platinum-based molecular sieve catalyst according to claim 8 is used to catalyze the reaction of propane dehydrogenation.

10. A method for dehydrogenating propane, characterized in that: The platinum-based molecular sieve catalyst described in claim 9 is loaded into a quartz glass reaction tube with an inner diameter, hydrogen and nitrogen are introduced in a volume ratio of 1:19, and then the temperature is raised to 500-600°C for reduction treatment for 1-2 hours, and then propane and nitrogen are introduced in a volume ratio of 1:3 for reaction.

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