Low-temperature plasma-assisted high-entropy oxide catalyst, preparation method and application

Abstract

The application discloses a low-temperature plasma assisted high-entropy oxide catalyst, a preparation method and application. The catalyst comprises a high-entropy spinel phase and a ceria fluorite phase, and the high-entropy spinel phase contains at least one metal element of iron, nickel, chromium, manganese, cobalt, magnesium or zinc. The preparation method comprises the steps of mixing metal salts, solvothermal treatment, separation and washing, drying and calcination in an oxygen-containing atmosphere. When hydrogen is prepared, pyrolysis is first performed on organic waste, and then the pyrolysis product and water vapor are introduced into a dielectric barrier discharge region filled with the catalyst to perform plasma catalytic reforming. The application can promote the breaking of C-C bonds and C-O bonds in the organic matter, improve the hydrogen production, and realize the resource utilization of the organic waste.

Description

Technical Field

[0001] This invention relates to the fields of organic waste resource utilization, hydrogen production, low-temperature plasma catalysis, and high-entropy oxide catalytic materials, specifically to a low-temperature plasma-assisted high-entropy oxide catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen has a high energy density, making it suitable as a clean energy carrier and an important raw material for the synthesis of ammonia, methanol, and various chemical products. Currently, industrial hydrogen production still largely relies on the thermochemical conversion of fossil fuels such as natural gas and coal, typically requiring high reaction temperatures and resulting in significant energy consumption and carbon emissions. Therefore, developing hydrogen production technologies based on renewable or waste carbon-containing raw materials with relatively mild reaction conditions has become an important research direction in the fields of organic waste resource utilization and low-carbon energy production.

[0003] Organic waste such as kitchen waste oil and waste animal and vegetable oils mainly contain triglycerides, free fatty acids, and their degradation products, and are characterized by high organic matter content, high calorific value, and wide availability. Existing technologies typically employ pyrolysis, gasification, or catalytic reforming to convert this type of organic waste. Specifically, under heating conditions, organic waste can be decomposed into gaseous hydrocarbons, oxygenated organic matter, tar, and other volatile components, which are then converted into hydrogen-containing syngas through steam reforming, pyrolysis, and water-gas shift reactions.

[0004] However, organic waste such as kitchen waste oil has a complex composition, and its pyrolysis products typically include long-chain hydrocarbons, short-chain hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, and other oxygen-containing organic compounds, involving the activation and breaking of various chemical bonds such as C-C bonds, C-H bonds, and C-O bonds. Therefore, traditional thermocatalytic reforming processes often require high reaction temperatures and are prone to problems such as condensation of heavy components, carbon deposition, and sintering of catalyst active components, which in turn lead to reactor blockage, catalyst deactivation, and a decrease in hydrogen yield.

[0005] Low-temperature plasma, especially dielectric barrier discharge plasma, can generate high-energy electrons, free radicals, ions, and excited-state molecules under ambient or near-ambient pressure. These active species can promote the activation of organic molecules and the breaking of chemical bonds, thus enabling some reactions that originally required higher temperatures to occur at relatively lower external heating temperatures. Therefore, using low-temperature plasma for the reforming of organic waste pyrolysis products to produce hydrogen is beneficial in reducing dependence on high-temperature reaction conditions.

[0006] However, when using low-temperature plasma alone to treat pyrolysis products of organic waste, the reaction pathway is relatively complex, easily generating methane and other low-carbon hydrocarbon byproducts. Furthermore, the plasma input energy may not be fully utilized for the target reforming reaction. To improve hydrogen yield and syngas selectivity, existing research typically places the catalyst within or downstream of the plasma reaction region, allowing the plasma active species and catalyst surface active sites to interact.

[0007] Traditional single-metal or few-component metal oxide catalysts have a relatively limited number of active sites, which may make it difficult to simultaneously promote the adsorption, activation, and conversion of multiple intermediate products when treating complex organic waste pyrolysis products. In addition, some metal catalysts are prone to carbon deposition, agglomeration, or sintering during the reaction, thus affecting catalytic stability.

[0008] Therefore, it is necessary to provide a new organic waste hydrogen production technology by constructing a catalyst with active sites and combining it with a dielectric barrier discharge plasma reaction system to improve the activation and reforming capacity of complex organic waste pyrolysis products, reduce insufficiently converted hydrocarbon products, and obtain a high yield of hydrogen-rich syngas at a relatively low external heating temperature. Summary of the Invention

[0009] This invention aims to solve the technical problems in existing organic waste pyrolysis reforming hydrogen production processes, such as high reaction temperature, complex composition of pyrolysis volatiles, limited types of catalyst active sites, easy carbon deposition, and the need to improve hydrogen yield. It provides a catalyst and a method for producing hydrogen from organic waste through low-temperature plasma-assisted high-entropy oxide catalytic reforming.

[0010] This invention constructs a biphase high-entropy oxide catalyst comprising a high-entropy spinel phase and a cerium dioxide fluorite phase, and places this catalyst within a dielectric barrier discharge plasma generation region. This allows the volatile components generated from the pyrolysis of organic waste to undergo cracking, reforming, and water-gas shift reactions under the combined action of water vapor, plasma active species, and catalyst active sites. This increases hydrogen production, promotes the deep conversion of hydrocarbon intermediates, and reduces the dependence of the organic waste catalytic reforming process on high-temperature reaction conditions.

[0011] According to a first aspect of the present invention, a low-temperature plasma-assisted high-entropy oxide catalyst is provided, characterized in that it comprises a high-entropy spinel phase and a fluorite-type cerium dioxide phase; wherein the high-entropy spinel phase contains iron, nickel, chromium, manganese and metal M, wherein metal M is selected from cobalt, magnesium and zinc.

[0012] Preferably, the metal M is cobalt; iron, cobalt, nickel, chromium and manganese are in equimolar amounts in the metal raw materials for preparing the high-entropy spinel phase.

[0013] Preferably, the high-entropy spinel phase and the fluorite-type cerium dioxide phase coexist in the same catalyst particle and contact each other to form a phase interface; the X-ray diffraction pattern of the low-temperature plasma-assisted high-entropy oxide catalyst simultaneously has characteristic diffraction peaks of both the spinel phase and the fluorite-type cerium dioxide phase, and its Raman spectrum simultaneously has characteristic peaks of both the spinel phase and the fluorite-type cerium dioxide phase.

[0014] According to a second aspect of the present invention, a method for preparing the low-temperature plasma-assisted high-entropy oxide catalyst is provided, comprising the following steps: adding a metal salt of cerium, iron, nickel, chromium, manganese and metal M to a mixed solvent containing isopropanol and glycerol to obtain a metal salt mixture; subjecting the metal salt mixture to solvothermal treatment to obtain a catalyst precursor; separating, washing and drying the catalyst precursor; and calcining the dried catalyst precursor in an oxygen-containing atmosphere to form the high-entropy spinel phase and the fluorite-type cerium dioxide phase.

[0015] Preferably, the metal salts are selected from one of the nitrates, chlorides, sulfates, and acetates of the corresponding metals; the molar ratio of cerium, iron, nickel, chromium, manganese, and metal M is 1:1:1:1:1:1; the volume ratio of isopropanol to glycerol is 5:1; the solvothermal treatment is performed at a temperature of 180°C for 16 hours; and the calcination is performed at a temperature of 1000°C for 2 hours.

[0016] According to a third aspect of the present invention, a method for producing hydrogen from organic waste by low-temperature plasma-assisted catalytic reforming is provided, comprising the following steps: pyrolyzing the organic waste to obtain pyrolysis products; introducing the pyrolysis products into a dielectric barrier discharge plasma reaction region, wherein the low-temperature plasma-assisted high-entropy oxide catalyst is disposed in the dielectric barrier discharge plasma reaction region; and performing low-temperature plasma-assisted catalytic reforming on the pyrolysis products in the presence of the low-temperature plasma-assisted high-entropy oxide catalyst to obtain hydrogen-containing gas.

[0017] Preferably, the organic waste is organic waste containing triglycerides and / or free fatty acids, selected from waste cooking oil, waste edible oil, waste animal and vegetable oils and combinations thereof; the pyrolysis products and water vapor are introduced together into the dielectric barrier discharge plasma reaction region for water vapor reforming; the plasma discharge power is 5-100W, and the external heating temperature of the dielectric barrier discharge plasma reaction region is 0-600℃.

[0018] Preferably, the feed flow rate of the organic waste is 0.05–10 mL / min, the amount of the low-temperature plasma-assisted high-entropy oxide catalyst is 0.5–10 g, the feed flow rate of water is 0.05–10 mL / min, and the flow rate of the protective gas is 10–500 mL / min; the protective gas is nitrogen, argon, or a combination thereof.

[0019] According to a fourth aspect of the present invention, a dielectric barrier discharge plasma reactor for low-temperature plasma-assisted catalytic reforming of organic waste to produce hydrogen is provided, comprising a quartz reaction tube, a pyrolysis region, a plasma catalytic region, an inner electrode, an outer electrode, quartz wool, and the aforementioned low-temperature plasma-assisted high-entropy oxide catalyst; the pyrolysis region and the plasma catalytic region are arranged sequentially along the material flow direction, the plasma catalytic region is a coaxial cylindrical dielectric barrier discharge structure, the inner electrode is disposed inside the quartz reaction tube, the outer electrode is disposed outside the quartz reaction tube, a discharge gap is formed between the inner electrode and the inner wall of the quartz reaction tube, and the quartz wool and the aforementioned low-temperature plasma-assisted high-entropy oxide catalyst are disposed in the discharge gap.

[0020] Preferably, the wall thickness of the quartz reaction tube is 2-4 mm, the radial width of the discharge gap is 0.5-3.5 mm, and the fiber diameter of the quartz wool is 3-5 μm; the inner electrode is a rod-shaped high-voltage electrode, and the outer electrode is a mesh-shaped grounding electrode covering the outer wall of the quartz reaction tube.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects.

[0022] First, this invention employs a biphase high-entropy oxide catalyst comprising a high-entropy spinel phase and a cerium dioxide fluorite phase. The high-entropy spinel phase contains multiple metallic elements, providing various types of metal active sites, and generates lattice distortion and electronic structure modulation through multi-component composition; the cerium dioxide fluorite phase provides oxygen vacancies and oxygen migration channels. The interface formed by the contact between the two crystal phases is beneficial for improving the adsorption, activation, and conversion capabilities of organic waste pyrolysis products.

[0023] Second, the present invention places the biphase high-entropy oxide catalyst directly in the discharge region of the dielectric barrier discharge plasma, so that the high-energy electrons, free radicals, ions and excited-state particles generated by the plasma work together with the active sites of the catalyst, which is beneficial to promoting the breaking of C-C bonds, C-H bonds and C-O bonds in the pyrolysis volatiles and the steam reforming reaction, thereby increasing the yield of hydrogen and carbon monoxide.

[0024] Third, the two-phase high-entropy oxide catalyst of this invention exhibits superior catalytic performance under plasma-assisted conditions compared to using either a high-entropy spinel catalyst or a cerium dioxide catalyst alone. When using a combination of the two-phase high-entropy oxide catalyst and plasma, the hydrogen yield reaches 77.27%. The results are higher than those obtained by using plasma alone, plasma with a single high-entropy spinel catalyst, and plasma with a single cerium dioxide catalyst. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 The two-phase high-entropy oxide catalyst HESO-F prepared in Example 1, the high-entropy spinel catalyst Co-HESO prepared in Comparative Example 1, and the cerium dioxide catalyst prepared in Comparative Example 2 are described. The X-ray diffraction pattern.

[0027] Figure 2 The two-phase high-entropy oxide catalyst HESO-F prepared in Example 1, the high-entropy spinel catalyst Co-HESO prepared in Comparative Example 1, and the cerium dioxide catalyst prepared in Comparative Example 2 are described. The Raman spectrum.

[0028] Figure 3 The images show scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDX-X) elemental distribution maps of the biphase high-entropy oxide catalyst HESO-F prepared in Example 1. The elemental distribution maps show the distribution of iron, cobalt, nickel, chromium, manganese, cerium, and oxygen in the catalyst particles.

[0029] Figure 4 The images show a high-resolution transmission electron microscope (TEM) image and a fast Fourier transform (FFT) image of a selected region of the biphase high-entropy oxide catalyst HESO-F prepared in Example 1. FFT1 and FFT2 are used to characterize the crystal structures of the cerium dioxide fluorite phase and the high-entropy spinel phase in the catalyst, respectively.

[0030] Figure 5 This is a schematic diagram of the two-stage dielectric barrier discharge plasma catalytic reforming reaction device used in this invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to embodiments, comparative examples, and test examples. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Without departing from the concept of the present invention, those skilled in the art can make conventional adjustments to the types of raw materials, equipment specifications, process parameters, and testing conditions.

[0032] The term "high-entropy spinel" as used in this article "Two-phase low-temperature plasma-assisted catalyst" refers to a catalyst that simultaneously contains a multimetallic spinel crystal phase composed of Fe, Co, Ni, Cr, and Mn, as well as a fluorite-type phase. The two crystal phases are in contact with each other at the micrometer or nanometer scale.

[0033] The term "low-temperature plasma" as used in this article refers to non-thermal equilibrium plasma generated through dielectric barrier discharge.

[0034] I. Raw Materials and Reagents

[0035] The six metal precursors used in Example 1 are shown in the table below.

[0036]

[0037] II. Catalyst Preparation

[0038] Example 1: Fe-Co-Ni-Cr-Mn high-entropy spinel / Preparation of two-phase low-temperature plasma-assisted catalyst HESO-F

[0039] Weigh out 0.008 mol of each The six metal salts were added to a mixed solvent consisting of 200 mL isopropanol and 40 mL glycerol. The mixture was stirred at 800 rpm for 30 min to obtain a homogeneous solution.

[0040] The mixed solution was transferred to a solvothermal reactor lined with polytetrafluoroethylene. After sealing, it was treated at 180°C for 16 h. After treatment, it was cooled to room temperature. The resulting mixture was centrifuged at 10,000 rpm for 10 min, the supernatant was discarded, and the solid was collected. The solid was washed three times with anhydrous ethanol.

[0041] The washed solid was dried in an oven at 80°C for 4 h. The dried precursor was placed in a quartz boat and then placed in a high-temperature tube furnace. Under a dry air atmosphere at a flow rate of 100 mL / min, the temperature was increased to 1000°C at a rate of 1°C / min and held for 2 h. Then, it was allowed to cool naturally to room temperature under continuous dry air circulation. This sample was named HESO-F.

[0042] In this embodiment, the molar ratio of the six metal precursors is Ce:Fe:Co:Ni:Mn:Cr=1:1:1:1:1:1.

[0043] Comparative Example 1: Preparation of Ce-free high-entropy spinel catalyst Co-HESO

[0044] The catalyst was prepared according to the method of Example 1, except that no additives were used. ,the remaining The feed amount for each catalyst was 0.008 mol. After undergoing the same solvothermal, centrifugal, washing, drying, and calcination treatments, a high-entropy spinel catalyst was obtained, named Co-HESO.

[0045] Comparative Example 2 Catalyst preparation

[0046] The catalyst was prepared according to the method of Example 1, the only difference being that only 0.008 mol of [a specific ingredient] was added. F2g, without the addition of metal salts of Fe, Co, Ni, Mn, and Cr. After undergoing the same solvothermal, centrifugal, washing, drying, and calcination treatments, the following was obtained: catalyst.

[0047] III. Low-Temperature Plasma-Assisted Reforming Device

[0048] Example 4: Two-stage pyrolysis-dielectric barrier discharge catalytic reforming device

[0049] The reactor body is a straight quartz reaction tube with a length of 700 mm, an outer diameter of 25 mm, an inner diameter of 18 mm, and a quartz tube wall thickness of 3.5 mm.

[0050] The upstream region of the quartz reaction tube constitutes the pyrolysis zone, which is used to pyrolyze kitchen waste oil to produce volatile products.

[0051] The downstream region of the quartz reaction tube constitutes the dielectric barrier discharge plasma generation region. A 300 mm long, 15 mm outer diameter stainless steel rod is coaxially inserted into the quartz reaction tube and serves as the inner electrode. The outer wall of the quartz tube is covered with a 70 mm long stainless steel mesh, which serves as the outer electrode and is grounded. A discharge gap with a radial width of 1.5 mm is formed between the outer surface of the inner electrode and the inner wall of the quartz tube.

[0052] The catalyst is filled within the discharge gap, and the catalyst bed corresponds axially to the external electrode. The quartz wool fibers have a diameter of 3–5 μm, and the quartz wool is used to immobilize the catalyst by mixing it with the catalyst.

[0053] The pyrolysis zone and the plasma catalysis zone are heated independently by two tube furnaces. DBD plasma is generated using a sinusoidal AC high-voltage power supply with a peak-to-peak voltage of up to 30 kV and a frequency of 10 kHz.

[0054] The reaction products are discharged from the downstream of the reaction tube. After separation of the liquid products and water, the gas enters the online gas chromatograph or gas bag.

[0055] IV. Low-Temperature Plasma-Assisted Catalytic Reforming for Hydrogen Production

[0056] Example 5: Hydrogen production from kitchen waste oil coupled with HESO-F catalyst and low-temperature plasma

[0057] Weigh 0.5 g of the HESO-F catalyst prepared in Example 1, fill it into the discharge gap of the plasma generation region, and fix it with quartz wool.

[0058] Connect the gas and liquid pipelines and perform an airtightness check on the system. As a protective gas and carrier gas, it is introduced into the reactor at a flow rate of 200 mL / min to remove air from the system.

[0059] exist Under continuous flow conditions, the downstream plasma catalytic region is heated to 500°C at a heating rate of 15°C / min.

[0060] The upstream pyrolysis zone was heated to 550℃ at a heating rate of 15℃ / min.

[0061] Waste cooking oil is continuously fed into the pyrolysis zone at a flow rate of 0.05 mL / min; at the same time, ultrapure water is fed into the inlet of the second reaction zone at a flow rate of 0.09 mL / min.

[0062] Turn on the AC high-voltage power supply to ignite and maintain the DBD plasma. The actual discharge power is 60 W and the frequency is 10 kHz.

[0063] The reaction start time was defined as the moment when waste cooking oil and water were introduced and the plasma was activated. The reaction lasted for 30 minutes, and the outlet gas was sampled every 5 minutes.

[0064] Determined according to the aforementioned gas chromatography method. CO , and Hydrocarbon products.

[0065] Comparative Example 3: Only low-temperature plasma was used, without a catalyst.

[0066] Except that the discharge gap was not filled with catalyst, the reaction was carried out according to the method of Example 5.

[0067] Comparative Example 4: Using HESO-F catalyst but without turning on the plasma.

[0068] The method of Example 5 was followed, in which 0.5 g of HESO-F catalyst was loaded and subjected to pyrolysis and steam reforming, except that the high-voltage power supply was not turned on and no plasma was generated.

[0069] Comparative Example 5: Co-HESO catalyst coupled with low-temperature plasma

[0070] The HESO-F catalyst in Example 5 was replaced with 0.5 g of the Co-HESO catalyst prepared in Comparative Example 1, while the other reaction conditions remained the same.

[0071] Comparative Example 6 Catalyst coupling with low-temperature plasma

[0072] The HESO-F catalyst in Example 5 was replaced with 0.5 g of the catalyst prepared in Comparative Example 2. Catalyst, with all other reaction conditions remaining the same.

[0073] V. Catalyst Structure Characterization Results

[0074] Test Case 1 XRD Analysis

[0075] HESO-F prepared in Example 1, Co-HESO prepared in Comparative Example 1, and HESO prepared in Comparative Example 2 were compared. XRD testing was performed, and the results are as follows: Figure 1 As shown.

[0076] HESO-F samples simultaneously exhibited spinel and fluorite crystal phases. The diffraction peaks correspond to the crystal phases. Co-HESO mainly exhibits diffraction peaks for the spinel crystal phase. The diffraction peaks are mainly those of the fluorite phase. Within the instrument's detection limit, no diffraction peaks clearly attributable to other impurity phases were observed in HESO-F, indicating that the prepared sample contains at least a spinel phase and a fluorite phase. Mutually.

[0077] Figure 1 The standard card used in this application is: Fluorite type. [PDF#00-043-1002, cubic Fm-3m]; spinel phase [PDF#00-010-0325, cubic Fd-3m]. The mass fractions of the two phases in HESO-F are 26.02 wt% and 73.98 wt%, respectively.

[0078] Test Case 2 Raman Analysis

[0079] Raman tests were performed on the three catalysts mentioned above, and the results are as follows: Figure 2 As shown. HESO-F sample in Nearby display Characteristic peaks, in Defect-related peaks are shown nearby, and in and Nearby, spinel-related vibrational peaks are observed. Co-HESO and Each exhibits characteristic peaks corresponding to its single main crystalline phase.

[0080] The Raman and XRD results corroborate each other, indicating that both spinel-related structures and fluorite-type structures exist simultaneously in HESO-F. structure.

[0081] Test Example 3: SEM-EDS Analysis

[0082] HESO-F SEM-EDS results are as follows Figure 3 As shown in the image, the SEM image shows that the sample consists of approximately spherical particles with an average particle size of 1.5 μm and a particle size distribution range of 0.5–3.0 μm.

[0083] The EDS surface distribution plots show that Fe, Co, Ni, Cr, Mn, Ce, and O are all distributed within the granular regions, and no significant large-scale agglomeration was observed at the tested spatial resolution. The EDS atomic percentages of each element are 6.55%, 6.62%, 6.53%, 7.13%, 6.25%, 5.50%, and 61.41%, respectively.

[0084] Test Example 4: HRTEM and FFT Analysis

[0085] HESO-F HRTEM and FFT results are as follows Figure 4 As shown in the HRTEM image, two adjacent crystal regions can be observed. Fast Fourier Transform was performed on regions FFT1 and FFT2, respectively.

[0086] The FFT1 region shows the [(200)] crystal plane, with the zone axis being [

[011] ], belonging to the [fluorite type]. [Phase]; The FFT2 region shows the [(313)] crystal plane, with the zone axis being [[1-11]], belonging to the [spinel phase].

[0087] The two crystalline regions are adjacent at the nanoscale, indicating the presence of a spinel phase and The phases form a contact interface.

[0088] VI. Results of Catalytic Reforming Performance

[0089] Test Example 5: Gas Product Yields of Each System

[0090] The reaction was carried out according to Example 5 and Comparative Examples 3-6. The gaseous product data are shown in the table below.

[0091] Table 1. Yields of reaction products using catalysts from the examples and comparative examples (unit: ...) )

[0092]

[0093] The data in the table show that, under HESO-F coupled with plasma, the H2 yield is 77.27%, which is approximately 3.07 times that of the plasma-only system and approximately 1.42 times that of the Co-HESO / plasma system. The yield of CO in the HESO-F / plasma system was approximately 2.15 times that of the other groups. The CO yield in the HESO-F / plasma system was also higher than that of the other groups.

[0094] Meanwhile, in the HESO-F / plasma system Hydrocarbon yields were lower than those using plasma alone, Co-HESO / plasma, and The plasma system indicates that it is beneficial for promoting further cracking and reforming of heavier hydrocarbons or oxygen-containing volatile components.

[0095] Based on the structural characterization results, the HESO-F prepared in Example 1 simultaneously exhibits high-entropy spinel-related crystal phases and fluorite-type phases. The two crystalline phases exhibit relatively uniform distribution of Fe, Co, Ni, Cr, Mn, Ce, and O at the particle scale. HRTEM and FFT results further indicate that the two crystalline phases form contact regions at the nanoscale. Based on catalytic data, HESO-F coupled with dielectric barrier discharge plasma... The CO yield is higher than that of plasma alone, HESO-F is plasma-free, Co-HESO is coupled with plasma, and The system coupled with plasma and reduced Product yield.

[0096] Figure 5 This is a schematic diagram of the two-stage dielectric barrier discharge plasma catalytic reforming reaction device used in this invention. Figure 5 In the diagram, 1 is a quartz reaction tube, 2 is a pyrolysis zone, 3 is an inner electrode, 4 is quartz wool, 5 is a two-phase high-entropy oxide catalyst, and 6 is an outer electrode. Among these, the inner electrode 3 is a high-voltage electrode, the outer electrode 6 is a grounding electrode, and the quartz wool 4 and the two-phase high-entropy oxide catalyst 5 are disposed in the discharge gap formed between the inner electrode 3 and the inner wall of the quartz reaction tube 1.

[0097] The above embodiments are merely preferred embodiments of the present invention. For those skilled in the art, appropriate adjustments or equivalent substitutions can be made to the types of raw materials, test parameters, data processing methods, and activity grading methods without departing from the principles of the present invention; all such adjustments or substitutions should be considered to fall within the protection scope of the present invention.

Claims

1. A low-temperature plasma-assisted high-entropy oxide catalyst, characterized in that, It includes a high-entropy spinel phase and a fluorite-type cerium dioxide phase; the high-entropy spinel phase contains iron, nickel, chromium, manganese and metal M, wherein metal M is selected from cobalt, magnesium and zinc.

2. The low-temperature plasma-assisted high-entropy oxide catalyst according to claim 1, characterized in that, The metal M is cobalt; iron, cobalt, nickel, chromium and manganese are in equimolar amounts in the metal raw materials used to prepare the high-entropy spinel phase.

3. The low-temperature plasma-assisted high-entropy oxide catalyst according to claim 1 or 2, characterized in that, The high-entropy spinel phase and the fluorite-type cerium dioxide phase coexist in the same catalyst particle and contact each other to form a phase interface; the X-ray diffraction pattern of the low-temperature plasma-assisted high-entropy oxide catalyst has characteristic diffraction peaks of both the spinel phase and the fluorite-type cerium dioxide phase, and its Raman spectrum also has characteristic peaks of both the spinel phase and the fluorite-type cerium dioxide phase.

4. A method for preparing a low-temperature plasma-assisted high-entropy oxide catalyst according to any one of claims 1 to 3, characterized in that, The process includes the following steps: adding metal salts of cerium, iron, nickel, chromium, manganese, and metal M to a mixed solvent containing isopropanol and glycerol to obtain a metal salt mixture; and subjecting the metal salt mixture to solvothermal treatment to obtain a catalyst precursor. The catalyst precursor is separated, washed, and dried; The dried catalyst precursor is calcined in an oxygen-containing atmosphere to form the high-entropy spinel phase and the fluorite-type cerium dioxide phase.

5. The preparation method according to claim 4, characterized in that, The metal salts are selected from one of the nitrates, chlorides, sulfates, and acetates of the corresponding metals; the molar ratio of cerium, iron, nickel, chromium, manganese, and metal M is 1:1:1:1:1:1, and the volume ratio of isopropanol to glycerol is 5:1; the solvothermal treatment is performed at a temperature of 180°C for 16 hours, and the calcination is performed at a temperature of 1000°C for 2 hours.

6. A method for producing hydrogen from organic waste through low-temperature plasma-assisted catalytic reforming, characterized in that, The method includes the following steps: pyrolyzing organic waste to obtain pyrolysis products; introducing the pyrolysis products into a dielectric barrier discharge plasma reaction region, wherein the dielectric barrier discharge plasma reaction region is provided with a low-temperature plasma-assisted high-entropy oxide catalyst as described in any one of claims 1 to 3; and performing low-temperature plasma-assisted catalytic reforming on the pyrolysis products in the presence of the low-temperature plasma-assisted high-entropy oxide catalyst to obtain hydrogen-containing gas.

7. The method according to claim 6, characterized in that, The organic waste is organic waste containing triglycerides and / or free fatty acids, selected from kitchen waste oil, waste cooking oil, waste animal and vegetable oils and combinations thereof; the pyrolysis products and water vapor are introduced together into the dielectric barrier discharge plasma reaction region for water vapor reforming; the plasma discharge power is 5-100W, and the external heating temperature of the dielectric barrier discharge plasma reaction region is 0-600℃.

8. The method according to claim 6 or 7, characterized in that, The feed flow rate of the organic waste is 0.05–10 mL / min, the amount of the low-temperature plasma-assisted high-entropy oxide catalyst is 0.5–10 g, the feed flow rate of water is 0.05–10 mL / min, and the flow rate of the protective gas is 10–500 mL / min; the protective gas is nitrogen, argon, or a combination thereof.

9. A dielectric barrier discharge plasma reactor for low-temperature plasma-assisted catalytic reforming of organic waste to produce hydrogen, characterized in that, The device comprises a quartz reaction tube, a pyrolysis region, a plasma catalytic region, an inner electrode, an outer electrode, quartz wool, and a low-temperature plasma-assisted high-entropy oxide catalyst as described in any one of claims 1 to 3; the pyrolysis region and the plasma catalytic region are arranged sequentially along the material flow direction, the plasma catalytic region is a coaxial cylindrical dielectric barrier discharge structure, the inner electrode is disposed inside the quartz reaction tube, the outer electrode is disposed outside the quartz reaction tube, a discharge gap is formed between the inner electrode and the inner wall of the quartz reaction tube, and the quartz wool and the low-temperature plasma-assisted high-entropy oxide catalyst are disposed in the discharge gap.

10. The dielectric barrier discharge plasma reaction apparatus according to claim 9, characterized in that, The quartz reaction tube has a wall thickness of 2-4 mm, the discharge gap has a radial width of 0.5-3.5 mm, and the quartz wool has a fiber diameter of 3-5 μm. The inner electrode is a rod-shaped high-voltage electrode, and the outer electrode is a mesh-shaped grounding electrode covering the outer wall of the quartz reaction tube.

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