Microwave catalytic dehydrogenation method

Abstract

This invention relates to the field of catalytic dehydrogenation, specifically to a microwave catalytic dehydrogenation method. Under microwave irradiation, alkanes are contacted with a microwave dehydrogenation catalyst to catalytically dehydrogenate low-carbon olefins. The catalyst is composed of n layers of vertically stacked columns with a honeycomb structure, where n ≥ 4, and the pore density of each honeycomb structure column is 3-23 pores / cm². 2 In this method, the through-holes of any two adjacent honeycomb structures are staggered. The microwave catalytic dehydrogenation method provided by the invention catalyzes the dehydrogenation reaction through microwave radiation, and also provides the necessary energy for the dehydrogenation reaction from within the reaction system, effectively reducing reaction energy consumption. The production process is efficient and clean, and can significantly improve the yield of low-carbon olefins compared with traditional steam thermal cracking methods.

Description

Technical Field

[0001] This invention relates to the field of catalytic dehydrogenation, and more specifically to a microwave catalytic dehydrogenation method. Background Technology

[0002] For a long time, my country has used naphtha to produce low-carbon olefins. With the increasing scale of petrochemical production facilities, the processing capacity of a single oil refining unit in my country has exceeded 10 million tons per year, while the ethylene production capacity of its supporting ethylene units has reached 800,000 to 1.2 million tons per year. However, with the dwindling petrochemical resources, the production cost of the crude oil-based petrochemical industry has been increasing year by year. Against this backdrop, the development of a wider range of low-carbon olefin feedstock resources has attracted widespread attention from chemical companies worldwide. With the application of gas recovery technologies in oil and gas fields, refineries, and chemical plants, more and more saturated low-carbon alkanes, including methane, ethane, propane, n-butane, and isobutane, are being recovered and enriched for use in the production of low-carbon olefins. The dehydrogenation reaction of saturated alkanes is a strongly endothermic process. Traditional steam cracking involves huge energy and material consumption, placing extremely high demands on the high-temperature resistance and creep resistance of the furnace body, furnace chamber, and furnace tubes. Therefore, reducing the production cost and energy consumption of low-carbon olefins, and finding a greener, more convenient, and more efficient production method, is beneficial for further expanding the scope of low-carbon alkane resource exploration and utilization.

[0003] Microwaves are a type of electromagnetic wave. When molecules in a substance are exposed to microwave radiation, locally charged dipole molecules will vibrate rapidly in the rapidly changing electromagnetic field of the microwave. The collisions and friction between molecules can raise the temperature of the substance itself, making it a highly efficient and clean heating energy source.

[0004] Many organic reactants cannot directly and significantly absorb microwave energy. However, by focusing high-intensity continuous or pulsed microwave radiation onto certain specific solid catalyst beds, the microwaves can excite the active sites in the catalyst to generate energy. This energy can catalyze dehydrogenation reactions and also provide the necessary energy for the dehydrogenation reaction from within the reaction system. To efficiently utilize microwave energy for the catalytic dehydrogenation of alkanes, it is necessary to find more suitable catalysts. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high production cost, high energy and material consumption, and low production efficiency in the production of olefins from saturated alkanes in the prior art, and to provide a microwave catalytic dehydrogenation method and its application in the preparation of low-carbon olefins.

[0006] To achieve the above objectives, the present invention provides a microwave catalytic dehydrogenation method, wherein, under microwave irradiation, alkanes are contacted with a microwave dehydrogenation catalyst to catalytically dehydrogenate and prepare low-carbon olefins.

[0007] The catalyst is composed of n layers of honeycomb-structured pillars stacked vertically, where n ≥ 4, and the pore density of each honeycomb-structured pillar layer is 3-23 pores / cm². 2 ;

[0008] In this structure, the through-holes of any two adjacent honeycomb layers are staggered with each other.

[0009] The microwave catalytic dehydrogenation method provided by this invention uses microwave radiation to catalyze the dehydrogenation reaction and provide the necessary energy for the dehydrogenation reaction from within the reaction system, effectively reducing reaction energy consumption and making the production process efficient and clean.

[0010] The microwave catalytic dehydrogenation method for preparing low-carbon olefins provided by this invention can significantly improve the yield of low-carbon olefins compared with the traditional steam thermal cracking method. Attached Figure Description

[0011] Figure 1 This is a schematic diagram showing the layer-by-layer disassembly of the catalyst microstructure in Example 1;

[0012] Figure 2 This is a schematic diagram of the pore offset structure of the upper and lower honeycomb structures of the catalyst in Example 1, as observed from the top of the catalyst. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] In this invention, unless otherwise stated, the term "height direction" in the specification refers to the direction of extension of the central axis of the column of the catalyst, "top of the catalyst" refers to the two end faces of the column perpendicular to the central axis of the column, and directional terms such as "upper" and "lower" refer to the relative positions along the height direction.

[0015] This invention provides a microwave catalytic dehydrogenation method, comprising: contacting an alkane with a microwave dehydrogenation catalyst under microwave irradiation to catalytically dehydrogenate and prepare low-carbon olefins;

[0016] The catalyst is composed of n layers of honeycomb-structured pillars stacked vertically, where n ≥ 4, and the pore density of each honeycomb-structured pillar layer is 3-23 pores / cm². 2 ;

[0017] In this structure, the through-holes of any two adjacent honeycomb layers are staggered with each other.

[0018] According to the present invention, the microwave dehydrogenation catalyst is formed by stacking n layers of honeycomb-structured pillars vertically. The through-pores of any two adjacent honeycomb structures are staggered to form a tortuous microchannel. This increases the catalyst porosity while providing more active sites through the staggered pore walls of the honeycomb structures. For example, it has the following characteristics: Figure 1 The catalyst with the microstructure shown is composed of six layers of honeycomb-structured pillars stacked vertically, with each layer having a pore density of 14-15 pores / cm². 2 Starting from the bottom, the center of each hole in the upper layer is offset relative to the center of the hole in the lower layer along the side length. For example, the hole offset of the upper and lower honeycomb structures visible from the top is as follows: Figure 2 As shown, by focusing high-intensity continuous or pulsed microwave radiation onto the bed of a microwave dehydrogenation catalyst, the microwaves can excite the active sites in the catalyst to generate energy. On the one hand, this catalyzes the dehydrogenation reaction, and on the other hand, it can provide the energy required for the dehydrogenation reaction from within the reaction system, further improving the olefin yield of alkane dehydrogenation to produce low-carbon olefins.

[0019] According to a preferred embodiment of the present invention, the number of layers n of the honeycomb structure column in the catalyst is 4-12, preferably 6-10. Under the above preferred conditions, it is beneficial to improve the contact efficiency between the catalyst and the material.

[0020] According to the present invention, the pores of the honeycomb structure pillars in the catalyst can be selected as any opening shape. Preferably, the pores of the honeycomb structure pillars are selected from one or more of circular, equilateral triangular, square, and regular hexagonal pores. In the above preferred cases, a larger specific surface area can be obtained through the pore wall structure, further increasing the active sites of the catalyst in microwave catalytic reaction.

[0021] According to the present invention, the offset direction of the pores in any two adjacent honeycomb structure columns in the catalyst is not specifically limited, as long as the above-mentioned structural requirements are met. In a preferred embodiment of the present invention, in the catalyst, the offset direction of the pores in the lower layer of the honeycomb structure columns can be the same as or different from the offset direction of the pores in the upper layer; for example, when the offset directions are the same, a stepped pore structure can be formed, and when the offset directions are different, an interlaced pore structure can be formed. Preferably, in any two adjacent honeycomb structures, the center of the through-hole in the lower honeycomb structure is offset along the side length or diameter direction of the through-hole relative to the center of the corresponding through-hole in the upper honeycomb structure.

[0022] According to a preferred embodiment of the present invention, in the catalyst, the offset of the center of the through-hole of the honeycomb structure is 0.1-0.9 times the side length or diameter of the hole, preferably 0.1-0.5 times, and more preferably 0.1, 0.125, 0.25, 0.33, or 0.5 times.

[0023] According to the present invention, the size of the catalyst can be controlled according to the specific catalytic reaction requirements, for example, it can be packed as a monolithic catalyst or packed with small-sized catalyst particles. When packed as small-sized catalyst particles, the diameter of the catalyst is preferably 5-10 mm and the height is 5-10 mm; more preferably, the diameter of the catalyst is 6-8 mm and the height is 6-8 mm. In the above preferred cases, it is beneficial to increase the porosity and specific surface area of ​​the overall catalytic system, which is further beneficial to reduce the reactor pressure drop and increase the reaction space velocity.

[0024] In this invention, the selection range for the catalyst composition is relatively wide, as long as it has the characteristic of efficiently converting microwave radiation energy into heat energy under microwave irradiation. Preferably, the catalyst contains at least one of carbon, silicon carbide, and an alloy, as well as a supported metal; more preferably, it contains carbon and / or silicon carbide and a supported metal. Preferably, the supported metal is selected from at least one of Group VB, VIII, and IB elements; more preferably, it contains at least one of vanadium, niobium, tantalum, iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, platinum, copper, silver, and gold; and more preferably, it contains at least one of platinum, gold, palladium, silver, copper, nickel, and vanadium.

[0025] According to a preferred embodiment of the present invention, based on the total amount of catalyst, the content of the supported metal is 0.1-10% by mass, preferably 0.1-5% by mass; the catalyst may also contain carbon, silicon carbide, and alloys in a content of 90-99.9% by mass, preferably 95-99.9% by mass.

[0026] According to a preferred embodiment of the present invention, the catalyst can be formed using 3D printing technology. A three-dimensional object is modeled using computer-aided design and modeling software, and the model is decomposed into an STL format document that can be built layer by layer. This document is provided to a 3D printer to form the desired three-dimensional object layer by layer using liquid or powdered building materials. Preferably, the 3D printing process is selective laser sintering or fused deposition modeling.

[0027] This invention does not impose any particular limitations on the parameters and conditions for 3D printing, as long as the above-mentioned catalyst can be formed, any conditions known in the art can be used. According to a preferred embodiment of the present invention, the 3D printing conditions include: a printing temperature of 150-1700℃ and a printing speed of 10-200mm / s.

[0028] For example, when the catalyst contains carbon and a supported metal, the preparation method of the catalyst includes: 3D printing a printing base to obtain a support framework; carbonizing the support framework under an inert atmosphere; and impregnating the support framework with a solution D containing an active metal to obtain a supported catalyst. Preferably, the printing base material is selected from at least one of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), nylon, polycarbonate (PC), polyurethane (PU), polytetrafluoroethylene (PTFF), polyethylene terephthalate (PET), and polylactic acid (PLA); preferably, the inert atmosphere is selected from one of vacuum, nitrogen, or argon atmosphere; wherein the vacuum degree under the vacuum atmosphere is less than 150 Pa; preferably, the carbonization conditions include: calcination at 120-300℃ for 1-5 h, followed by calcination at 500-3000℃ for 5-15 h; preferably, the molar concentration of the metal in the solution D is 0.1-10%, preferably 0.1-5%.

[0029] For example, when the catalyst comprises silicon carbide and a supported metal, the preparation method of the catalyst includes: impregnating silicon carbide powder with a solution D containing an active metal; drying the metal-loaded silicon carbide powder under an inert atmosphere to obtain supported silicon carbide powder; and printing the supported silicon carbide powder using 3D printing technology. Preferably, the molar concentration of the active metal in the solution D is 0.1-10%, more preferably 0.1-5%; preferably, the drying conditions include: a drying temperature of 150-300℃, more preferably 150-200℃; the inert atmosphere is selected from vacuum, nitrogen, or argon atmospheres; wherein the vacuum degree under the vacuum atmosphere is less than 150 Pa.

[0030] According to the present invention, the reaction raw materials for the alkane dehydrogenation reaction are subject to a wide range of requirements. Preferably, the alkane is selected from at least one of C1-C8 alkanes, and more preferably at least one of methane, ethane, propane, n-butane and isobutane.

[0031] According to a preferred embodiment of the present invention, the low-carbon olefin includes at least one selected from ethylene, propylene, 1-butene, 2-butene, and isobutene.

[0032] According to a preferred embodiment of the present invention, the conditions for the catalytic dehydrogenation reaction include: the microwave irradiation frequency is 0.5-30 GHz, preferably 0.9-22 GHz, and more preferably 0.9-2.5 GHz.

[0033] Too low a frequency of microwave irradiation may affect energy conversion efficiency, while too high a frequency will lead to a decrease in penetration. Under the above-mentioned preferred irradiation conditions, it is beneficial to promote the dehydrogenation reaction.

[0034] According to a preferred embodiment of the present invention, the conditions for the catalytic dehydrogenation reaction include: a reaction pressure of 0.1-1.0 MPa, preferably 0.1-0.5 MPa; a reaction temperature of 450-800°C, preferably 500-700°C; and a gas hourly space velocity (GHSV) of alkane of 5000-20000 h⁻¹. -1 Preferably 10000-15000h -1 Under the aforementioned preferred conditions, the reaction process can be scaled up.

[0035] According to a preferred embodiment of the present invention, the microwave irradiation is either continuous microwave irradiation or pulsed microwave irradiation, preferably continuous microwave irradiation. Using the above-mentioned preferred microwave irradiation method is beneficial for improving the selectivity of the dehydrogenation reaction.

[0036] According to a preferred embodiment of the present invention, the conditions for pulsed microwave irradiation are: pulse frequency of 1-10Hz, preferably 2-5Hz; and duty cycle of 0.1-1. Duty cycle is the output quantity for controlling microwave energy. Those skilled in the art will understand that when the duty cycle is 0.1, microwaves are present for 10% of the time, and no microwave radiation occurs at other times.

[0037] The present invention will be described in detail below through embodiments.

[0038] Example 1

[0039] The 3D structure of the catalyst was modeled using SolidWorks software. The catalyst has a diameter of 6 mm, a length of 6 mm, and is cut into 6 layers along the height direction, with a layer height of 1 mm. Each layer has four 2 mm diameter holes. Starting from the bottom, the center of each hole in the upper layer is offset by 1.66 mm relative to the center of the hole in the lower layer along any diameter direction. The microstructure of the catalyst layer by layer is shown below. Figure 1 As shown. The 3D model is converted into an STL format file for layer stacking using the export module in the software. The obtained STL model file is then provided to the MakerBot Replicator R2 fused deposition modeling 3D printer. Polypropylene filament is added to the material cylinder of the 3D printer, and the printing temperature is set to 185℃ and the printing speed is 60mm / s to print catalyst carrier particles.

[0040] The printed catalyst support particles were placed in a quartz tube in a quartz boat. Dry nitrogen gas was introduced to replace the air in the tube for 30 minutes. The quartz tube was then evacuated to a vacuum of 1 mmHg using a vacuum pump. The quartz tube was heated to 145°C and maintained for 3 hours. After the catalyst support in the quartz boat turned black, the heating temperature was increased to 750°C and maintained for 12 hours until the catalyst support was completely carbonized.

[0041] The fully carbonized catalyst support was placed in a 0.2% platinum chloride solution and stirred for 30 min. After filtration, the metal-loaded catalyst was placed in a quartz boat with a sealed quartz tube at both ends. Dry nitrogen gas was introduced into the quartz tube to replace the air in the tube. The quartz tube was heated to 450°C. After the temperature stabilized, high-purity hydrogen gas was introduced for 15 min, followed by the introduction of dry nitrogen gas to replace the air in the tube. The tube was then cooled to room temperature to obtain the activated carbon-based catalyst S1, which has a platinum content of 0.3% by mass and a carbon content of 99.7% by mass.

[0042] Measure 10 mL of catalyst S1 using a graduated cylinder and fill it into a quartz tube with an inner diameter of 20 mm, a wall thickness of 6 mm, and a length of 500 mm. Fill the middle section of the quartz tube with catalyst particles, and insert 5 mm diameter Al2O3 ceramic rings into both ends. Fix the filled quartz tube in the microwave radiation cavity of a microwave reactor, and control the flow rate of high-purity nitrogen gas to 10000 h⁻¹. -1 Turn on the microwave radiation source and adjust the microwave frequency to 2.45 GHz to bring the catalyst temperature to 630°C. After the system stabilizes for 30 minutes, introduce ethane gas at a gas space velocity of 10,000 h⁻¹. -1 The reaction pressure was 0.4 MPa. After 20 minutes, the tail gas was introduced into an Agilent 7890 gas chromatograph to analyze the composition of the gas after the reaction, and to calculate the conversion rate of low-carbon alkanes, the selectivity of low-carbon olefins and the yield. The results are shown in Table 1.

[0043] Example 2

[0044] The 3D structure of the catalyst was modeled using SolidWorks software. The catalyst was 6mm in diameter and 6mm in length, cut into 6 layers along the height direction, with a layer height of 1mm. Each layer had four regular hexagonal holes with a side length of 2mm. Starting from the bottom, the center of the hole in the upper layer was offset by 0.33mm relative to the center of the hole in the lower layer along any side. The constructed 3D model was converted into an STL format file of layer stacking using the software's export module. The obtained STL model file was provided to an EOSINT P760 selective laser sintering 3D printer. Nylon powder was added to the material cylinder of the 3D printer, and the printing temperature was set to 265℃ and the printing speed to 150mm / s to print the catalyst carrier particles.

[0045] The printed catalyst support particles were placed in a quartz tube in a quartz boat. Dry nitrogen gas was introduced to replace the air in the tube for 30 minutes. The quartz tube was then evacuated to a vacuum of 1 mmHg using a vacuum pump. The quartz tube was heated to 250°C and maintained for 3 hours. After the catalyst support in the quartz boat turned black, the heating temperature was increased to 1500°C and maintained for 12 hours until the catalyst support was completely carbonized.

[0046] Ammonium metavanadate with a molar concentration of 3% was dissolved in oxalic acid. The fully carbonized catalyst support was placed in the solution and stirred for 30 min. The catalyst loaded with metal was obtained by filtration and placed in a quartz boat with a quartz tube sealed at both ends. Dry air was passed through the quartz tube and the quartz tube was heated to 560°C to activate the catalyst for 60 min. The catalyst was then cooled to room temperature to obtain the activated carbon-based catalyst S2, which has a vanadium content of 1% by mass and a carbon content of 99% by mass.

[0047] Measure 10 mL of catalyst S2 using a graduated cylinder and fill it into a quartz tube with an inner diameter of 20 mm, a wall thickness of 6 mm, and a length of 500 mm. Fill the middle section of the quartz tube with catalyst S2, and insert Al2O3 ceramic rings with a particle size of 5 mm into both ends. Fix the filled quartz tube in the microwave radiation cavity of a microwave reactor, and control the flow rate of high-purity nitrogen gas to 10000 h⁻¹. -1 Turn on the microwave radiation source and adjust the microwave frequency to 0.915 GHz to bring the catalyst temperature to 630°C. After the system stabilizes for 30 minutes, propane gas is introduced at a gas hourly space velocity of 10,000 h⁻¹. -1 The reaction pressure was 0.3 MPa. After 20 minutes, the tail gas was introduced into an Agilent 7890 gas chromatograph to analyze the composition of the gas after the reaction, and to calculate the conversion rate of low-carbon alkanes, the selectivity of low-carbon olefins and the yield. The results are shown in Table 1.

[0048] Example 3

[0049] The method is the same as in Example 1, except that the microwave irradiation conditions are as follows: microwave frequency 2.45 GHz, pulsed microwave irradiation source with pulse frequency of 3 Hz and duty cycle of 0.5, catalyst temperature maintained at 550°C, and after the system stabilizes for 30 minutes, ethane gas is introduced at a gas space velocity of 10000 h⁻¹. -1 The reaction pressure was 0.4 MPa. After 20 minutes, the tail gas was introduced into an Agilent 7890 gas chromatograph to analyze the composition of the gas after the reaction, and to calculate the conversion rate of low-carbon alkanes, the selectivity of low-carbon olefins and the yield. The results are shown in Table 1.

[0050] Comparative Example 1

[0051] In a traditional steam pyrolysis evaluation apparatus, the radiant section tube is 1000 mm long and is heated by heating wires. Three heating and temperature monitoring points are distributed along the tube length, and the temperature of the heating points is controlled by a DCS (Distributed Control System). Upon startup, the furnace temperature is initially raised to 200°C, and distilled water is introduced at a flow rate of 108 g / h. After the distilled water is completely vaporized in the preheating section, the furnace temperature is gradually increased to the preset temperature and stabilized for 30 minutes. Then, ethane gas is introduced at a flow rate of 207 g / h, and the water-to-oil ratio is stably controlled at 0.4. The temperature of the three sections of the radiant section furnace tube is controlled at 860°C. After 20 minutes, the tail gas is introduced into an Agilent 7890 gas chromatograph to analyze the composition of the gas after the reaction, and to calculate the conversion rate of low-carbon alkanes, the selectivity of low-carbon olefins, and the yield.

[0052] Comparative Example 2

[0053] The method is the same as in Comparative Example 1, except that propane gas is used instead of ethane gas.

[0054] Table 1

[0055]

[0056] *Ethylene + Propylene

[0057] Examples 1 and Comparative Example 1, using ethane as a raw material, were prepared to obtain low-carbon olefin yields via microwave-assisted catalysis and steam thermal cracking, respectively. Data comparison showed that the olefin selectivity and olefin yield of Example 1 were significantly higher than those of Comparative Example 1. Examples 2 and Comparative Example 2, using propane as a raw material, were prepared to obtain low-carbon olefin yields via microwave-assisted catalysis and steam thermal cracking, respectively. Example 2 yielded a single propylene product, while Comparative Example 2 yielded multiple products, primarily ethylene and propylene. The results of Example 2 were significantly better than the sum of the ethylene and propylene products obtained in Comparative Example 2.

[0058] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A microwave-catalyzed dehydrogenation method, characterized in that, Under microwave irradiation, alkanes are contacted with a microwave dehydrogenation catalyst to catalytically dehydrogenate and prepare low-carbon olefins; the low-carbon olefins are selected from at least one of ethylene, propylene, 1-butene, 2-butene and isobutene. The catalyst is composed of n layers of honeycomb-structured pillars stacked vertically, where n ≥ 4, and the pore density of each honeycomb-structured pillar layer is 3-23 pores / cm². 2 The catalyst has a diameter of 5-10 mm and a height of 5-10 mm. In any two adjacent honeycomb structure columns, the center of the through hole in the lower column is offset relative to the center of the corresponding through hole in the upper column along the side length or diameter of the through hole, and the offset is 0.5-0.9 times the side length or diameter of the through hole. The catalyst comprises at least one of carbon, silicon carbide, and an alloy, as well as a supported metal; The load metal is selected from at least one of platinum, gold, palladium, and silver; Based on the total amount of catalyst, the content of the supported metal is 0.5-10% by mass. The microwave irradiation is continuous microwave irradiation; the conditions for the catalytic dehydrogenation reaction include: a reaction pressure of 0.1-0.5 MPa; a reaction temperature of 630-700 °C; and a alkane volume hourly space velocity of 10000-15000 h⁻¹. -1 .

2. The method according to claim 1, wherein, The catalyst has 4-12 layers of honeycomb-structured pillars.

3. The method according to claim 2, wherein, The catalyst has 6-10 layers of honeycomb-structured pillars.

4. The method according to claim 1, wherein, The holes in the columns of the honeycomb structure are selected from one or more of the following: circular, equilateral triangular, square, and regular hexagonal holes.

5. The method according to claim 1, wherein, The catalyst has a diameter of 6-8 mm and a height of 6-8 mm.

6. The method according to claim 1, wherein, The alkane is selected from at least one of methane, ethane, propane, n-butane, and isobutane.

7. The method according to any one of claims 1-6, wherein, The conditions for the catalytic dehydrogenation reaction include a microwave irradiation frequency of 0.5-30 GHz.

8. The method according to claim 7, wherein, The conditions for the catalytic dehydrogenation reaction include a microwave irradiation frequency of 0.9-22 GHz.

9. The method according to claim 8, wherein, The conditions for the catalytic dehydrogenation reaction include a microwave irradiation frequency of 0.9-2.5 GHz.

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