Method and system for concerted catalytic cracking of light alkane by coupling non-thermal plasma with molecular sieve

Abstract

The invention provides a method and a system for concerted catalytic cracking of light alkanes by coupling non-thermal plasmas with molecular sieves, and belongs to the field of chemical engineering. The invention aims to solve the problems of high temperature, high energy consumption, low olefin yield and the like in the current light alkane catalytic cracking reaction process. According to the method, a large number of high-energy active particles generated by the plasma are used for activating light alkane raw material molecules and promoting generation of free radicals, meanwhile, the excellent acid catalysis performance of the ZSM-5 molecular sieve is coupled, the reaction temperature is reduced, and the conversion rate of light alkane and the yield of low-carbon olefin (especially ethylene) are remarkably increased.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, and in particular to a new method and system for low-temperature, low-energy-consumption, and high-efficiency non-thermal plasma-coupled molecular sieve synergistic catalytic cracking of light alkanes. Background Art

[0002] The steam cracking process is currently the main method for industrial production of light olefins (such as ethylene and propylene). This process uses thermal cracking of alkane molecules to generate light olefins and a small amount of by-products under high temperature conditions (usually 800-900°C). However, such a high temperature makes the process energy-intensive. Steam cracking is one of the chemical processes with the highest energy consumption, and it also places stringent requirements on reactor materials and device design. In addition, under high temperature conditions, the cracking depth is difficult to accurately control, and a high proportion of by-products such as coke and aromatics are easily generated, which not only reduces the selectivity of the target product, but also aggravates the coking and deactivation of the cracking furnace. In order to solve these technical problems, scientists have been committed to developing more efficient and energy-saving cracking technologies as an alternative to traditional steam cracking.

[0003] Catalytic cracking technology, through the introduction of solid catalysts (such as HZSM-5 molecular sieves and metal oxides), enables efficient cracking of alkanes at relatively low temperatures (550-680°C). The acidic catalytic mechanism of this process is that the acidic sites on the catalyst surface effectively activate the alkane molecules, reducing the activation energy required for the reaction while promoting intermolecular reactions, thereby significantly reducing energy consumption. Furthermore, catalytic cracking offers significant advantages in regulating product distribution. For example, by adjusting the acid type and strength of the catalyst, the selectivity for light olefins can be effectively improved and the formation of byproducts can be reduced. However, catalytic cracking technology still faces several challenges in practical application. For example, although the operating temperature is lower than that of traditional processes, it is still relatively high, especially for light alkanes. Furthermore, the yield of light olefins under high-temperature conditions remains below the ideal level, limiting the economic viability of industrialization. Therefore, developing innovative, more efficient and stable cracking processes is an effective way to overcome these technical bottlenecks.

[0004] Plasma is a "fourth state of matter" composed of high-energy active particles such as high-energy electrons, ions, neutral molecules and free radicals. Plasma technology has received widespread attention in the field of catalysis in recent years. Its high-energy electrons and active particles can directly participate in chemical reactions, significantly increasing reaction rates and regulating reaction pathways. Currently, the research on plasma-involved catalytic processes mainly focuses on thermal plasma technology, such as rotating arc thermal plasma catalytic treatment of high-concentration VOC tail gas (CN110508109 A) and thermal plasma catalytic cracking of oil slurry (CN 113528173 A). Thermal plasma is characterized by high energy density, and the system temperature is usually around 1×10 3 ~2×104 K range, which is suitable for chemical processes that require extremely high reaction energy. In contrast, the temperature of non-thermal plasma is lower, and the system temperature is generally around 1×10 3 Although the temperature of electrons is within 1000 K, the temperature of electrons is much higher than that of ions and neutral molecules, showing a strong non-equilibrium state. This characteristic gives non-thermal plasma a unique advantage in reducing reaction temperature and energy consumption.

[0005] Light alkanes have relatively stable molecular structures and high C-C bond energies, and their cracking reactions present significant activation energy barriers. Effective conversion typically requires relatively high reaction temperatures, and catalytic cracking systems must maintain operating conditions above 550°C. Therefore, achieving low-temperature and efficient conversion of light alkanes has always been a major technical bottleneck in the fields of thermal and catalytic cracking. Based on this, non-thermal plasmas can excite high-energy electrons to promote free radical generation and induce carbon bond cleavage, thereby activating light alkanes. This approach is expected to enable catalytic cracking reactions at lower temperatures, showing broad prospects for constructing new, low-energy, highly selective, and green, controllable alkane cracking processes. Summary of the Invention

[0006] In response to the above problems, the present invention provides a new method and system for plasma-coupled molecular sieve synergistic catalytic cracking of light alkanes to solve technical problems such as high temperature, high energy consumption and low olefin yield in traditional catalytic cracking processes.

[0007] The principle of the present invention is to use plasma high-voltage discharge to generate high-energy active particles, which collide and bombard with raw gas molecules, causing excitation, dissociation and ionization, promoting the bond breaking and cracking of light alkane molecules and the occurrence of free radical reactions, reducing the reaction temperature, and at the same time combining the excellent acid catalytic properties of molecular sieves to achieve synergistic catalysis, thereby improving the catalytic cracking conversion rate of light alkanes and the yield of low-carbon olefins.

[0008] The present invention provides a method and system for the synergistic catalytic cracking of light alkanes using non-thermal plasma coupled molecular sieves, the technical solution of which is as follows:

[0009] A system for the coordinated catalytic cracking of light alkanes by non-thermal plasma coupled molecular sieves comprises a gas supply system, a plasma reaction system, a heating system, and a detection system.

[0010] The gas supply system includes a multi-component gas cylinder, which provides carrier gas for catalytic cracking reaction and atmosphere for plasma discharge.

[0011] The plasma reaction system includes a feedstock injection pump, a plasma reactor, a high-voltage plasma power supply, and a supporting voltage regulator and oscilloscope. Light alkane feedstock is pumped into the plasma reactor via a syringe pump. The plasma reactor utilizes a coaxial dual-dielectric barrier discharge (DBD) configuration. The reactor is constructed of insulating corundum. The high-voltage electrode is a metal cylinder positioned centrally within a coarse corundum tube, while the grounding electrode is a metal coaxial sleeve positioned externally. The high-voltage electrode is connected to the power supply, while the grounding electrode is grounded. The internal high-voltage electrode is placed within a thin corundum tube at the center of the coarse corundum tube. The ZSM-5 molecular sieve catalyst is placed between the thin corundum tube and the coarse corundum reactor, supported by a glass liner. The discharge region is a cavity extending from the inner wall of the coarse corundum reactor to the outer wall of the thin corundum tube. The reaction materials and carrier gas enter through the reactor's upper air inlet, while the reaction products exit through the lower air outlet. A thermocouple is inserted into the thin corundum tube at the reactor's lower end. To prevent discharge, the thermocouple is positioned 1 cm below the discharge region to measure the real-time reaction temperature.

[0012] The heating system includes an open, insulated tubular reactor and heating cables for the gas lines. The tubular reactor can provide heating from room temperature to 900°C. All gas lines are equipped with heating cables to maintain a constant temperature of 170°C, ensuring that the reaction products remain in a gaseous state.

[0013] The detection system includes a gas chromatograph, a mass spectrometer and an in-situ spectrometer. The reaction products are discharged from the lower end of the reactor and can enter the gas chromatograph or mass spectrometer for detection and analysis. An optical fiber is used to extend from the reactor window to the vicinity of the plasma reactor, and the monitored light signal is collected by a spectrometer connected to the optical fiber.

[0014] Preferably, the multi-component gas cylinders include nitrogen and argon, and each cylinder gas outlet is provided with a pressure gauge and a mass flow meter. The pressure gauge is used to monitor the carrier gas pressure, and the mass flow meter is used to control the flow of the carrier gas.

[0015] Preferably, the raw material injection pump is made of stainless steel, the syringe capacity is 10 μL to 60 mL, and the linear speed is 1 μm / min to 150 mm / min.

[0016] Preferably, the plasma generating power supply is a modulated pulse power supply with an adjustable frequency range of 5 to 20 kHz and an output voltage of 0 to 30 kV. The voltage regulator and oscilloscope monitor in real time and provide stable sinusoidal alternating current to the plasma reactor.

[0017] Preferably, the output power of the plasma reactor is 20 to 44 W.

[0018] Preferably, the high voltage electrode and the ground electrode are made of one of copper, stainless steel and platinum.

[0019] Preferably, the plasma reactor is a double-layer corundum tube, the thick corundum tube has a diameter of 10 mm and a length of 550 mm, and the thin corundum tube has a diameter of 3 mm and a length of 550 mm.

[0020] Preferably, the air inlet and air outlet joints at the upper and lower ends of the plasma reactor are made of insulating PEEK material.

[0021] Preferably, the catalyst is HZSM-5 molecular sieve, the upper and lower ends of the catalyst are fixed by quartz wool, the filler is between the double-layer corundum tubes, the particle size of the catalyst is 40-60 mesh, and the catalyst loading amount is 200 mg.

[0022] Preferably, the silicon-to-aluminum ratio of the HZSM-5 molecular sieve is one of 36, 85, and 200.

[0023] Preferably, the position of the catalyst bed is adjusted by the length of the glass liner. Optionally, the catalyst bed is adjusted to within or below the plasma discharge region.

[0024] Preferably, the catalytic cracking reaction temperature is 400-500°C.

[0025] Preferably, the light alkane feedstock is C5-C7 alkane.

[0026] Preferably, the in-situ optical emission spectrometer has a measurement range of 200 to 1100 nm, a slit width of 20 μm, and an exposure time of 2000 ms.

[0027] The beneficial effects of the non-thermal plasma coupled molecular sieve synergistic catalytic cracking method for light alkanes described in the present invention include:

[0028] 1. The present invention uses non-thermal plasma coupled with molecular sieves to catalyze the cracking of light alkanes. The high-energy active particles generated by plasma discharge have excitation, dissociation, and ionization effects on the alkane raw material molecules, promoting the bond breaking and cracking of the alkanes. At the same time, coupled with the acid catalysis of HZSM-5 molecular sieve, the conversion rate of alkanes and the yield of light olefins are greatly improved.

[0029] 2. The present invention uses non-thermal plasma coupled molecular sieves to catalytically crack light alkanes, achieving efficient directional conversion at a lower temperature, reducing reaction temperature and energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the non-thermal plasma coupled molecular sieve synergistic catalytic light alkane cracking system

[0031] In the attached figure:

[0032] 1. Raw material injection pump 2. Gas cylinder 3. Mass flow meter 4. Heat transmission cable

[0033] 5 High voltage electrode 6 Quartz wool 7 Ground electrode 8 HZSM-5 molecular sieve

[0034] 9 Tube furnace 10 PEEK interface 11 Thermocouple 12 Air inlet

[0035] 13 gas outlet 14 high voltage plasma power supply 15 thin corundum tube 16 thick corundum tube

[0036] 17 Glass liner 18 Oscilloscope 19 Voltage regulator 20 Mass spectrometer 21 Gas chromatograph

[0037] Figure 2 In situ optical emission spectra of n-hexane pyrolysis catalyzed by non-thermal plasma in nitrogen atmosphere

[0038] Figure 3 In situ optical emission spectra of n-hexane pyrolysis catalyzed by non-thermal plasma in argon atmosphere DETAILED DESCRIPTION

[0039] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings.

[0040] like Figure 1 As shown, the present invention provides a system for catalyzing the cracking of light alkanes by non-thermal plasma-coupled molecular sieves, including 1 raw material injection pump, 2 gas cylinders, 3 mass flowmeters, 4 heating cables, 5 high-voltage electrodes, 6 quartz wool, 7 ground electrodes, 8 HZSM-5 molecular sieves, 9 tubular furnaces, 10 PEEK interfaces, 11 thermocouples, 12 air inlets, 13 air outlets, 14 high-voltage plasma power supplies, 15 thin corundum tubes, 16 coarse corundum tubes, 17 glass liners, 18 oscilloscopes, 19 voltage regulators, 20 mass spectrometers, and 21 gas chromatographs.

[0041] Light alkane feedstock is pumped out via a syringe pump at a flow rate of 300 mg / h, with a carrier gas flow rate of 5 mL / min controlled by a mass flowmeter. After mixing with the carrier gas, the feedstock enters the plasma reactor through the inlet under heating conditions. After passing through the plasma discharge and catalyst coupling zone, cracking reactions occur, and gaseous products are discharged through the outlet and directly fed into a gas chromatograph or mass spectrometer for detection and analysis. The plasma reactor is housed in a tubular furnace that provides heating from room temperature to 900°C. The plasma reactor consists of a double-layered alumina tube. The high-voltage electrode is a metal wire located within the thin alumina tube, while the grounding electrode is a metal sheath located outside the coarse alumina tube. The catalyst is supported by a glass liner and placed between the outer and inner walls of the thin and coarse alumina tubes. The catalyst bed position can be adjusted by the height of the glass liner, and the catalyst is secured at the top and bottom with quartz wool. A thermocouple is inserted into the thin alumina tube at the lower end of the reactor. To prevent discharge, the thermocouple is placed 1 cm below the discharge zone to measure the real-time temperature during the reaction. Non-thermal plasma is generated by a high-voltage plasma power supply, and the plasma power is regulated and monitored by a voltage regulator and an oscilloscope.

[0042] In situ optical emission spectroscopy (OES) was used to detect the discharge process of the reaction in order to monitor the excited and ionized species (rotationally excited, vibrationally excited, and electronically excited molecules, ions, and free radicals) produced during the non-thermal plasma-coupled molecular sieve synergistic catalytic cracking of light alkanes, thereby studying the mechanism of non-thermal plasma-enhanced efficient directional cracking of light alkanes.

[0043] The HZSM-5 molecular sieve used in the examples and comparative examples of this application was purchased from commercial sources.

[0044] In the examples and comparative examples of the present application, n-hexane, n-pentane and n-heptane are used as raw materials for catalytic cracking of light alkanes.

[0045] [Example 1]

[0046] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was nitrogen, the non-thermal plasma power was 20W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0047] [Example 2]

[0048] The temperature of the catalytic cracking system was controlled at 450°C, the carrier gas was nitrogen, the non-thermal plasma power was 20W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0049] [Example 3]

[0050] The temperature of the catalytic cracking system was controlled at 500°C, the carrier gas was nitrogen, the non-thermal plasma power was 20W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0051] [Example 4]

[0052] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was nitrogen, the non-thermal plasma power was 30W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0053] [Example 5]

[0054] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was nitrogen, the non-thermal plasma power was 38W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0055] [Example 6]

[0056] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was nitrogen, the non-thermal plasma power was 44W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0057] [Example 7]

[0058] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was argon, the non-thermal plasma power was 44W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0059] [Example 8]

[0060] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was argon, the non-thermal plasma power was 44W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the catalytic cracking reaction of n-pentane were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0061] [Example 9]

[0062] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was argon, the non-thermal plasma power was 44W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-heptane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-pentane conversion rate and light olefin yield were calculated.

[0063] [Example 10]

[0064] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was nitrogen, and the non-thermal plasma power was 44W. Non-thermal plasma catalyzed n-hexane cracking reaction was carried out without loading the catalyst, and the discharge process of the non-thermal plasma was monitored by an in-situ emission spectrometer.

[0065] [Example 11]

[0066] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was argon, and the non-thermal plasma power was 44W. Non-thermal plasma catalyzed n-hexane cracking reaction was carried out without loading the catalyst, and the discharge process of the non-thermal plasma was monitored by an in-situ emission spectrometer.

[0067] [Comparative Example 1]

[0068] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was nitrogen, the non-thermal plasma power was 0W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0069] [Comparative Example 2]

[0070] The temperature of the catalytic cracking system was controlled at 450°C, the carrier gas was nitrogen, the non-thermal plasma power was 0 W, and the catalyst was placed in the plasma discharge region. The conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0071] [Comparative Example 3]

[0072] The temperature of the catalytic cracking system was controlled at 500°C, the carrier gas was nitrogen, the non-thermal plasma power was 0W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0073] [Comparative Example 4]

[0074] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was argon, the non-thermal plasma power was 44W, and the catalyst was placed outside and below the plasma discharge area. Gas chromatography was used to detect and analyze the conversion rate and olefin yield of the n-hexane catalytic cracking reaction, and the n-hexane conversion rate and light olefin yield were calculated.

[0075] [Comparative Example 5]

[0076] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was argon, the non-thermal plasma power was 0W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-hexane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-hexane conversion rate and light olefin yield were calculated.

[0077] [Comparative Example 6]

[0078] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was argon, the non-thermal plasma power was 0W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the catalytic cracking reaction of n-pentane were detected and analyzed by gas chromatography, and the n-pentane conversion rate and light olefin yield were calculated.

[0079] [Comparative Example 7]

[0080] The temperature of the catalytic cracking system was controlled at 400°C, the carrier gas was argon, the non-thermal plasma power was 0 W, the catalyst was placed in the plasma discharge region, and the conversion rate and olefin yield of the n-heptane catalytic cracking reaction were detected and analyzed by gas chromatography, and the n-heptane conversion rate and light olefin yield were calculated.

[0081] Table 1 Evaluation results of non-thermal plasma coupled molecular sieve synergistic catalytic cracking of light alkanes in Examples 1 to 9 and Comparative Examples 1 to 7

[0082]

[0083] From the evaluation results of the catalytic cracking performance of n-hexane of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be seen that at different temperatures, the catalytic cracking effect of n-hexane in the non-thermal plasma coupled HZSM-5 synergistic catalytic system is better than that in the traditional thermal catalytic system. The specific beneficial effects are reflected in the improvement of the n-hexane conversion rate and the increase in the yield of light olefin products.

[0084] From the evaluation results of n-hexane catalytic cracking of Example 1 and Examples 4 to 6 in Table 1, it can be seen that with the increase of plasma power, the catalytic cracking effect of n-hexane in the non-thermal plasma coupled HZSM-5 synergistic catalytic system shows a significant increasing trend. The specific beneficial effects are reflected in the significant improvement of n-hexane conversion rate and light olefin product yield, and the proportion of ethylene in the olefin product is significantly increased, indicating that the non-thermal plasma discharge power has a positive correlation with the cracking of alkanes.

[0085] From the evaluation results of the catalytic cracking of n-hexane in Example 6 and Comparative Example 4 in Table 1, it can be seen that the catalytic cracking effect of n-hexane is better when the catalyst bed is located in the discharge area than when the catalyst bed is located below the discharge area, and when the non-thermal plasma and HZSM-5 are in the same area, indicating that the synergistic catalytic effect is better when the non-thermal plasma is coupled with the catalyst.

[0086] From the evaluation results of the catalytic cracking performance of n-hexane in Example 6 and Comparative Example 5 in Table 1, it can be seen that the catalytic cracking effect of n-hexane in the non-thermal plasma coupled HZSM-5 synergistic catalytic system under argon atmosphere is better, indicating that optimizing the carrier gas type is one of the key factors in improving the conversion efficiency of light alkanes, and has important research and application value.

[0087] From the evaluation results of catalytic cracking of C5-C7 alkanes of Examples 7-9 and Comparative Examples 5-7 in Table 1, it can be seen that the introduction of non-thermal plasma under argon atmosphere can significantly improve the conversion rate of C5-C7 alkanes and the yield of light olefins.

[0088] Figure 2 and Figure 3 The in situ optical emission spectra measured in Example 10 and Example 11, respectively, detected the generation of CH·, C2·, and H· free radicals during the non-thermal plasma-catalyzed n-hexane cracking process under nitrogen and argon atmospheres, proving that non-thermal plasma can effectively stimulate the bond breaking and cracking of alkanes.

[0089] In summary, the method and system provided by the present invention for the synergistic catalytic cracking of light alkanes using non-thermal plasma coupled molecular sieves can achieve a n-hexane conversion rate and a light olefin yield at 400°C that are twice that of conventional thermal catalytic systems at the same temperature, indicating that the present invention has the advantages of achieving efficient catalytic cracking at lower temperatures, reducing energy consumption and increasing the yield of olefin products.

[0090] The above embodiments are merely preferred embodiments of the present invention and are used to illustrate the technical solutions of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and simple modifications, replacements, and improvements based on the embodiments of the present invention are all within the scope of protection of the present invention.

Claims

1. A method and system for the synergistic catalytic cracking of light alkanes by non-thermal plasma coupled molecular sieves, characterized in that: The system includes a gas supply system, a plasma coupled molecular sieve catalytic system, a heating system and a detection system; wherein, The gas supply system includes a multi-component gas cylinder, which provides carrier gas for the catalytic cracking reaction and a discharge atmosphere for the plasma; wherein the gas includes nitrogen and argon; The plasma-coupled molecular sieve catalytic system includes a raw material injection pump, a plasma reactor, a high-voltage plasma power supply, a matching voltage regulator and an oscilloscope; the light alkane raw material is pumped into the plasma reactor through a stainless steel raw material injection pump. The plasma reactor is a coaxial double-dielectric barrier discharge type. The reactor material is insulating corundum. The high-voltage electrode is a metal cylinder set in the center of the coarse corundum tube, and the grounding electrode is a metal coaxial sleeve set outside the coarse corundum tube. The high-voltage electrode is connected to the power supply, and the grounding electrode is grounded; the internal high-voltage electrode is placed in the fine corundum tube at the center of the coarse corundum tube, and the molecular sieve catalyst is placed between the fine corundum tube and the coarse corundum reactor, supported by a glass liner; the discharge area is a cavity from the inner wall of the coarse corundum reactor to the outer wall of the fine corundum tube; the reaction raw materials and carrier gas enter from the air inlet at the upper end of the reactor, and the reaction products are discharged from the air outlet at the lower end; the thermocouple is inserted into the fine corundum tube at the lower end of the reactor. To prevent the thermocouple from discharging, the thermocouple is set 1 cm below the discharge area to measure the real-time temperature of the reaction process; The heating system includes an open insulated tubular reactor and gas heating cables. The tubular reactor can provide heating from room temperature to 900°C. All gas paths are heated at a constant temperature of 170°C by heating cables to ensure that the reaction products are in gaseous state. The detection system includes a gas chromatograph, a mass spectrometer, and an in-situ optical emission spectrometer (OES). The reaction products are discharged from the lower end of the reactor and can enter the gas chromatograph or mass spectrometer for detection and analysis. The in-situ optical emission spectrometer is used to monitor the non-thermal plasma discharge process.

2. The system according to claim 1, wherein: A pressure gauge and a mass flow meter are installed at the gas outlet of each cylinder. The pressure gauge is used to monitor the carrier gas pressure, and the mass flow meter is used to control the flow of the carrier gas.

3. The system according to claim 1, wherein: The plasma generating power supply is a modulated pulse power supply with an adjustable frequency range of 5 to 20 KHz and an output voltage of 0 to 30 KV.

4. The system according to claim 1, wherein: The reactor is made of corundum; the high-voltage electrode and the grounding electrode are made of copper, stainless steel, or platinum; and the air inlet and the air outlet are made of insulating polyetheretherketone (PEEK).

5. The system according to claim 1, wherein: The molecular sieve catalyst is HZSM-5 catalyst, the particle size of the catalyst is 40-60 mesh, the catalyst filler is 200 mg, and is fixed by quartz wool.

6. A method for realizing non-thermal plasma coupled molecular sieve synergistic catalytic cracking of light alkanes using the system of claim 1, characterized in that: The high-energy active particles generated by the plasma reactor are used to excite light alkane raw material molecules and promote the generation of free radicals. At the same time, the HZSM-5 catalyst is coupled and combined with the catalytic effect of its acidic sites to achieve synergistic catalysis with the plasma, thereby improving the conversion rate of light alkanes and the yield of low-carbon olefins.

7. The method for synergistic catalytic cracking of light alkanes using non-thermal plasma coupled molecular sieves according to claim 6, characterized in that: The output power of the plasma catalytic reactor is 20 to 44W.

8. The method for synergistic catalytic cracking of light alkanes using non-thermal plasma coupled molecular sieves according to claim 6, characterized in that: The catalytic cracking reaction temperature is 400-500°C.

9. The method for synergistic catalytic cracking of light alkanes using non-thermal plasma coupled molecular sieves according to claim 6, characterized in that: The position of the catalyst bed is adjusted by the length of the glass liner. Optionally, the catalyst bed can be located in or below the plasma discharge region.

10. The method for synergistic catalytic cracking of light alkanes using non-thermal plasma coupled molecular sieves according to claim 6, characterized in that: Using C5-C7 alkanes as light alkane raw materials, the raw material conversion rate and low-carbon olefin yield obtained by the non-thermal plasma coupled molecular sieve catalytic light alkane cracking system are significantly better than those of the traditional thermal catalytic system.

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