Methane oxidation coupling core-shell boron-based catalyst, preparation method and application thereof

Abstract

The application discloses a methane oxidation coupling core-shell boron-based catalyst, which has a core-shell structure, wherein B2O3, which is an active component, is used as a shell, and a metal oxide additive MO supported by a carrier Z is used as a core x The chemical general formula of the core can be expressed as MO x / Z@B2O3; wherein the metal oxide additive MO x is composed of one or a combination of CoO x or NiO x ; the weight ratio of B2O3 in the catalyst composition is 0-50 wt%, the weight ratio of MO x is 0-10 wt%, and the rest is the carrier Z. The preparation method of the catalyst for catalyzing methane oxidation coupling provided by the application has the advantages of cheap raw materials, mild reaction conditions and easy operation. The method provided by the application first uses a cheap and easily available boron-based catalyst to realize the methane selective oxidation coupling reaction, has high C2 selectivity and low CO2 selectivity, and provides a new type of catalyst for designing the efficient and directional conversion of methane into high-value-added C 2+ hydrocarbon compounds, and has industrial application potential.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst application, and particularly relates to a catalyst for selective preparation of C 2+ Boron-based catalysts for hydrocarbons, methods of making and using the same. BACKGROUND

[0002] With the increasing global energy demand, there is an increasing demand for efficient conversion and utilization of clean carbon resources such as natural gas. Methane is the main component of natural gas, but due to its high C-H bond energy and weak polarity, efficient activation and conversion of methane has been one of the important challenges in the field of catalysis. At present, the chemical conversion of methane can be divided into indirect conversion and direct conversion. The indirect conversion route is commonly used in industry, that is, methane is converted into synthesis gas (H2+CO) through steam reforming reaction, and then used to produce methanol and hydrocarbon fuels by Fischer-Tropsch synthesis; however, this method has the disadvantages of long route, high energy consumption and excessive carbon dioxide emission. In contrast, direct conversion of methane has obvious advantages such as short reaction path and mild reaction conditions, and therefore has attracted more and more attention from researchers. The reported direct conversion routes of methane mainly include the following: (1) pyrolysis and aromatization; (2) oxidative and non-oxidative coupling to prepare C 2+ hydrocarbons; (3) partial oxidation to prepare C1 oxygen-containing products such as formaldehyde and methanol (Pierre, Schwac, Xiu L, et al. Direct conversion of methane to value-added chemicals over heterogeneous catalysts: challenges and prospects [J]. Chemical Reviews, 2017, 117(13): 8497-8520; Lunsford J. The catalytic oxidation coupling of methane [J]. Angewandte Chemie international Edition, 1995, 34(9): 970-980; Tai W, Baltrusaitis J. CH4 conversion to value added products: Potential, limitations and extensions of a single step heterogeneous catalysis [J]. Applied Catalysis B-Environmental, 2016, 198: 525-547).

[0003] Ethylene is a basic raw material for the chemical industry, and its derivatives account for more than 75% of all petrochemical products. The production capacity of ethylene is an important indicator of the development level of a country's oil and chemical industry. Keller et al. first reported various metal oxide catalysts for the oxidative coupling of methane to C2 hydrocarbons in 1982 (Keller G, Bhasin M. Synthesis of ethylene via oxidative coupling of methane: I. Determination of active catalysts [J]. Journal of Catalysis, 1982, 73(1): 9-19). In the following decades, researchers have prepared and tested thousands of catalysts for the oxidative coupling of methane to olefins, but the yield of C2 hydrocarbons still cannot reach the industrial requirement of 30%. The catalysts reported in previous studies are mostly metal-based catalysts, such as MnO x -Na2WO4 / SiO2and Li / MgO catalysts, but such catalysts usually require high temperature (> 800℃) for the oxidative coupling of methane, which easily leads to the generation of excessive oxidation product CO2. Recent reports show that non-metallic boron-based catalysts can achieve selective oxidation of methane to formaldehyde at lower temperatures, and have excellent resistance to deep oxidation, thus attracting more and more attention (Tian J, Tan J, Zhang Z, et al. Direct conversion of methane to formaldehyde and CO on B2O3 catalysts [J]. Nature Communications, 2020, 11(1): 5693; Han P, Yan R, Wei Y, et al. Mechanistic insights into radical-induced selective oxidation of methane over nonmetallic boron nitride catalysts [J]. Journal of the American Chemical Society, 2023, 145(19): 10564-10575.). However, the regulation of the selectivity of boron-based catalysts for the oxidative coupling of methane, especially the preparation of C 2+ products, is still a difficult problem. Therefore, the development of new boron-based catalysts for the oxidative coupling of methane has great potential application value. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application aims to provide a kind of for catalyzing methane oxidation coupling selectively preparing C 2+ Core-shell type non-metallic boron oxide catalyst for hydrocarbon and its preparation method and application. In order to achieve the above purpose, the solution of the present application is:

[0005] A kind of methane oxidation coupling core-shell type boron-based catalyst, the catalyst has core-shell structure, active component B2O3 is outer shell, metal oxide additive MO x For inner core, its chemical general formula can be expressed as MO x / Z@B2O3;Wherein, metal oxide additive MO x It is one or a combination of two of CoO x Or NiO x ; The weight ratio of B2O3 in the catalyst composition is 0-50wt%, the weight ratio of MO x 0-10wt%, the rest is carrier Z.

[0006] Preferably, the carrier Z is made of one or a combination of BN, SiO2, TiO2, Al2O3, ZnO, MgO, ZrO2, CeO2, GaO2, InO2 or molecular sieve.

[0007] A kind of preparation method of methane oxidation coupling core-shell type boron-based catalyst, the specific steps are as follows:

[0008] (1) metal oxide additive loading: the metal precursor salt is dissolved in solvent, then the carrier is stirred, the obtained mixture is heated and evaporated, the obtained solid is dried and calcined to obtain MO x / Z precursor;

[0009] (2) metal oxide additive activation: the MO x / Z precursor prepared in step (1) is added to an organic solvent for solvothermal reaction, the collected solid is washed and dried, and then calcined to obtain activated MO x / Z precursor;

[0010] (3) active component B2O3 coating: the activated MO x / Z precursor prepared in step (2) is added to boric acid solution for stirring, the obtained mixture is heated and evaporated, and the obtained solid is dried and calcined.

[0011] Preferably, the metal precursor salt in step (1) is one or a combination of cobalt chloride, cobalt oxalate, cobalt sulfate, cobalt nitrate, cobalt acetate, nickel nitrate, nickel sulfate, nickel chloride, nickel sulfamate or nickel bromide.

[0012] Preferably, the solvent in step (1) is one or a combination of water, ethanol and acetone.

[0013] Preferably, the solvothermal reaction condition in step (2) is: the reaction atmosphere is inert atmosphere, the reaction temperature is 100-300℃, the reaction pressure is 0.1-3 MPa, and the reaction time is 1-24 h.

[0014] Preferably, the calcination condition is: the calcination atmosphere is air, the calcination temperature is 300-800℃, and the calcination time is 1-10 h.

[0015] The aforementioned catalyst is applied in the preparation of C2 hydrocarbon compounds by catalyzing methane oxidative coupling reaction, and specifically comprises the following steps: 2+ The aforementioned catalyst is applied in the preparation of C2 hydrocarbon compounds by catalyzing methane oxidative coupling reaction, and specifically comprises the following steps:

[0016] The methane oxidative coupling core-shell boron-based catalyst MO x The methane oxidative coupling core-shell boron-based catalyst MO

[0017] Preferably, the activation time is 0.5-3 h, and the activation temperature is 400-800℃.

[0018] Preferably, the continuous flow reactor is selected from one of a fixed bed reactor or a moving bed reactor.

[0019] The design principle of the present application is as follows:

[0020] The mechanism of the methane oxidative coupling reaction provided by the present application is as follows: the B2O3 active site on the methane oxidative coupling core-shell boron-based catalyst can adsorb oxygen to form active oxygen species, and the formed active oxygen species attacks the C-H bond of methane to cause the C-H bond to break. In the process of methane C-H bond breaking, part of the methyl radical intermediates (CH3·) formed by the broken bond can be captured by the active site, so that surface C-C bond coupling occurs to form C2 products. In addition, due to the low melting point of B2O3, it is in a flowing molten state under the reaction conditions, and the exposed metal oxide promoter sites can further assist the C-H bond breaking of methane to generate methyl radicals and make them couple to generate C2 products in the high-temperature gas phase, thereby further improving the conversion rate of the methane oxidative coupling reaction and the selectivity of the products.

[0021] Compared with the existing catalyst for catalytic methane oxidative coupling and the preparation method thereof, the present application has the following advantages:

[0022] (1) The method for catalytic methane oxidative coupling provided by the present application successfully realizes the directional conversion of methane into coupled C 2+ products at a lower temperature (650 DEG C) and a smaller amount of catalyst (100 mg).

[0023] (2) The preparation method of the catalyst for catalytic methane oxidative coupling provided by the present application has the advantages of inexpensive raw materials, mild reaction conditions and easy operation.

[0024] (3) The core-shell type boron-based catalyst provided by the present application has high C2 selectivity, low CO2 selectivity and meets the needs of green and sustainable development when applied to the catalytic methane oxidative coupling reaction, which provides a new type of catalyst for the design of efficient directional conversion of methane into high-value C 2+ hydrocarbon compounds, and has industrial application potential. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The X-ray diffraction (XRD) pattern of the 5wt%CoO x / γ-Al2O3@B2O3 catalyst provided by the present application is shown in the following figure:

[0026] Figure 2 The figure showing the change of C2 product selectivity of the 5wt%CoO x / γ-Al2O3@B2O3 catalyst and the B2O3 / γ-Al2O3 catalyst provided by the present application under different methane conversion rates is shown in the following figure: DETAILED DESCRIPTION

[0027] The present application will be further described in detail below in combination with the examples. It should also be understood that the following examples are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application. The specific mass, reaction time and temperature, process parameters and the like in the examples are only one example in the appropriate range, and some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application all belong to the protection scope of the present application. The specific technology or condition not specified in the examples is the technology or condition described in the literature in the art or according to the product instruction. The reagent or instrument not specified by the manufacturer can be a conventional product that can be purchased in the market.

[0028] Example 1

[0029] The specific preparation steps of the catalyst for catalytic methane oxidative coupling to prepare C 2+ hydrocarbons are as follows:

[0030] (1) Loading of metal oxide promoter: 0.492 g of cobalt nitrate hexahydrate was dissolved in 20 mL of deionized water, and then 2.0 g of γ-Al2O3 support was added. The resulting mixture was continuously stirred for 1 h and then evaporated in a water bath at 70 °C. The resulting solid was further dried in a vacuum at 80 °C for 8 h and then calcined in a muffle furnace at 500 °C for 4 h under an air atmosphere to obtain a 5wt%CoO x / γ-Al2O3 precursor;

[0031] (2) Activation of metal oxide promoter: 2.0 g of the 5wt%CoO x / γ-Al2O3 precursor prepared in step (1) was placed in a reaction kettle, and then 4 g of 1-octanol was added. Subsequently, the reaction kettle was sealed after being filled with 1 MPa of N2, and a solvothermal reaction was performed at 250 °C for 2 h. The resulting solvothermal reaction product was centrifuged, and the obtained solid was washed three times with 50 mL of acetone and 50 mL of ethanol, respectively. The washed solid was dried in a vacuum at 80 °C for 8 h and then calcined in a muffle furnace at 400 °C for 2 h under an air atmosphere to obtain an activated 5wt%CoO x / γ-Al2O3 precursor;

[0032] (3) Coating of active component B2O3: 0.533 g of boric acid was dissolved in 10 mL of deionized water under ultrasonic irradiation at room temperature for 5 min to obtain a boric acid solution. The boric acid solution was added to 1.0 g of the activated 5wt%CoO x / γ-Al2O3 precursor prepared in step (2), and the resulting mixture was continuously stirred for 1 h and then evaporated in a water bath at 60 °C. The resulting solid was further dried in a vacuum at 60 °C for 8 h and then calcined in a muffle furnace at 600 °C for 5 h under an air atmosphere to obtain a 5wt%CoO x / γ-Al2O3@B2O3 catalyst. The XRD characterization results of the obtained 5wt%CoO x / γ-Al2O3@B2O3 catalyst are shown in Figure 1 .

[0033] It can be seen from Figure 1 that the obtained 5wt%CoO x / γ-Al2O3@B2O3 catalyst formed obvious diffraction peaks at 14.5° and 27.9°, which are attributed to B2O3, and no characteristic diffraction peaks of CoO x were observed; this indicates that the particle size of the metal oxide CoO x is small and well dispersed.

[0034] The evaluation steps of the catalyst are as follows:

[0035] 100 mg 5wt%CoO x The B2O3 / γ-Al2O3@CoO catalyst was loaded into a fixed bed reactor, and after passing a mixed gas composed of N2and O2in a volume ratio of 1:1, it was heated and activated to 650°C at a heating rate of 7°C / min for 2 h. Then the raw material gas composed of CH4and O2was passed to carry out the catalytic methane oxidative coupling reaction; wherein the reaction temperature was 650°C, the heating rate was 7°C / min, the total flow rate of the reaction gas was 30 mL / min, the partial pressure of CH4was 32 kPa, the partial pressure of O2was 32 kPa, and the total pressure of the reaction was normal pressure (101.3 kPa). The final product was analyzed by a gas chromatograph, and the evaluation results are shown in Table 2 and Figure 2 .

[0036] Example 2

[0037] The preparation method of the catalyst for catalyzing methane oxidative coupling to prepare C 2+ The preparation steps of the hydrocarbon catalyst are as follows:

[0038] Boric acid was dissolved in 10 mL of deionized water at room temperature for 5 min to prepare a boric acid solution, and 1.0 g of a γ-Al2O3 carrier was added to the boric acid solution. The mixture was continuously stirred for 1 h and then evaporated to dryness in a water bath at 60°C. The obtained solid was further dried under vacuum at 60°C for 8 h and then placed in a muffle furnace and calcined at 600°C in an air atmosphere for 5 h to obtain a B2O3 / γ-Al2O3 catalyst.

[0039] The evaluation steps of the catalyst were referred to Example 1, except that the B2O3 / γ-Al2O3@CoO catalyst was replaced by the B2O3 / γ-Al2O3 catalyst; and the total flow rate of the reaction gas was changed to 45 mL / min. The reaction results are shown in Table 1. x The evaluation steps of the catalyst were referred to Example 1, except that the B2O3 / γ-Al2O3@CoO catalyst was replaced by the B2O3 / γ-Al2O3 catalyst; and the total flow rate of the reaction gas was changed to 45 mL / min. The reaction results are shown in Table 1.

[0040] Example 3

[0041] The preparation method of the catalyst for catalyzing methane oxidative coupling to prepare C 2+ The preparation method of the catalyst for catalyzing methane oxidative coupling to prepare C

[0042] The evaluation steps of the catalyst were referred to Example 1, except that the B2O3 / γ-Al2O3@CoO catalyst was replaced by the B2O3 / ZrO2 catalyst; and the total flow rate of the reaction gas was changed to 10 mL / min. The reaction results are shown in Table 1. x The evaluation steps of the catalyst were referred to Example 1, except that the B2O3 / γ-Al2O3@CoO catalyst was replaced by the B2O3 / ZrO2 catalyst; and the total flow rate of the reaction gas was changed to 10 mL / min. The reaction results are shown in Table 1.

[0043] Example 4

[0044] C2 hydrocarbons from methane by oxidative coupling 2+ The preparation method of the hydrocarbon catalyst was reference to Example 2, except that the γ-Al2O3 carrier was replaced by a ZnO carrier, and the amount of the ZnO carrier was 1.0 g, to obtain a catalyst B2O3 / ZnO.

[0045] The evaluation steps of the catalyst were reference to Example 1, except that the 5wt% CoO x / γ-Al2O3@B2O3 catalyst was replaced by a B2O3 / ZnO catalyst; and the total flow rate of the reaction gas was changed to 10 mL / min; and the reaction results are shown in Table 1.

[0046] Example 5

[0047] C2 hydrocarbons from methane by oxidative coupling 2+ The preparation method of the hydrocarbon catalyst was reference to Example 2, except that the γ-Al2O3 carrier was replaced by a SiO2 carrier, and the amount of the SiO2 carrier was 1.0 g, to obtain a catalyst B2O3 / SiO2.

[0048] The evaluation steps of the catalyst were reference to Example 1, except that the 5wt% CoO x / γ-Al2O3@B2O3 catalyst was replaced by a B2O3 / SiO2 catalyst; and the total flow rate of the reaction gas was changed to 10 mL / min; and the reaction results are shown in Table 1.

[0049] Example 6

[0050] C2 hydrocarbons from methane by oxidative coupling 2+ The preparation method of the hydrocarbon catalyst was reference to Example 2, except that the γ-Al2O3 carrier was replaced by a TiO2 carrier, and the amount of the TiO2 carrier was 1.0 g, to obtain a catalyst B2O3 / TiO2.

[0051] The evaluation steps of the catalyst were reference to Example 1, except that the 5wt% CoO x / γ-Al2O3@B2O3 catalyst was replaced by a B2O3 / TiO2 catalyst; and the total flow rate of the reaction gas was changed to 10 mL / min; and the reaction results are shown in Table 1.

[0052] Table 1 Influence of the carrier on the selectivity of the boron oxide catalyst in the methane coupling reaction

[0053]

[0054] As can be seen from Table 1, under the conditions of 650 ℃ and near 2% methane conversion, the sum of C2 and CO product selectivity of methane oxidative coupling reaction on the supported boron catalyst reaches nearly 95%, and the selectivity of deep oxidation product CO2 is less than 5%. Among them, when the carrier is γ-Al2O3, the C2 selectivity of the catalyst can be as high as 34.5%.

[0055] Example 7

[0056] Catalyst for catalyzing methane oxidative coupling to prepare C 2+ hydrocarbons was prepared similarly to Example 1, except that in step (1), the amount of cobalt nitrate hexahydrate was changed to 0.492 g, and the remaining conditions were the same, to obtain the catalyst 5wt%NiO x / γ-Al2O3@B2O3.

[0057] The evaluation of the catalyst was carried out according to Example 1, except that the 5wt%CoO x / γ-Al2O3@B2O3 catalyst was replaced by the 5wt%NiO x / γ-Al2O3@B2O3 catalyst; the reaction results are shown in Table 2.

[0058] Table 2 Influence of metal oxide additives on the performance of boron-based catalysts in methane coupling reaction

[0059]

[0060] As can be seen from Table 2 and Figure 2 , under the conditions of 650 ℃ and near 3% methane conversion, the coupling C2 product selectivity of the B2O3 / γ-Al2O3 catalyst after adding metal oxide additives is obviously improved. By comparing the addition of metal oxides NiO x and CoO x in Table 1, it can be found that the addition of CoO x brings higher C2 selectivity improvement, and the C2 selectivity is increased from 34.5% of B2O3 / γ-Al2O3 to 52.3% of 5wt%CoO x / γ-Al2O3@B2O3.

[0061] Example 8

[0062] Catalyst for catalyzing methane oxidative coupling to prepare C 2+ hydrocarbons was prepared similarly to Example 1, except that in step (1), the amount of cobalt nitrate hexahydrate was changed to 0.492 g, and the remaining conditions were the same, to obtain the catalyst 5wt%NiO x / γ-Al2O3@B2O3.

[0063] The catalyst evaluation procedure was similar to Example 1, except that the 5 wt% CoO x / γ-Al2O3@B2O3 catalyst was replaced by 1 wt% CoO x / γ-Al2O3@B2O3 catalyst; the total flow rate of the reaction gas was changed to 15 mL / min; the reaction results are shown in Table 3.

[0064] Example 9

[0065] For catalyzing the oxidative coupling of methane to prepare C 2+ The hydrocarbon catalyst was prepared in a similar manner to Example 1, except that the amount of cobalt nitrate hexahydrate in step (1) was changed to 0.246 g, and the other conditions were the same, and the catalyst 2.5 wt% CoO x / γ-Al2O3@B2O3 was prepared.

[0066] The catalyst evaluation procedure was similar to Example 1, except that the 5 wt% CoO x / γ-Al2O3@B2O3 catalyst was replaced by 2.5 wt% CoO x / γ-Al2O3@B2O3 catalyst; the total flow rate of the reaction gas was changed to 15 mL / min; the reaction results are shown in Table 3.

[0067] Example 10

[0068] For catalyzing the oxidative coupling of methane to prepare C 2+ The hydrocarbon catalyst was prepared in a similar manner to Example 1, except that the amount of cobalt nitrate hexahydrate in step (1) was changed to 0.984 g, and the other conditions were the same, and the catalyst 10 wt% CoO x / γ-Al2O3@B2O3 was prepared.

[0069] The catalyst evaluation procedure was similar to Example 1, except that the 5 wt% CoO x / γ-Al2O3@B2O3 catalyst was replaced by 10 wt% CoO x / γ-Al2O3@B2O3 catalyst; the total flow rate of the reaction gas was changed to 45 mL / min; the reaction results are shown in Table 3.

[0070] Table 3 Effect of the loading amount of the additive on the performance of the boron oxide catalyst in the methane coupling reaction

[0071]

[0072] As can be seen from Table 3, the product selectivity of the catalytic methane oxidative coupling reaction is different for catalysts with different metal oxide loadings at 650 °C and near 3% methane conversion. When the loading is 5 wt%, the sum of the selectivity of C2and CO products on the catalyst is more than 95% (CO:C2≈1:1), and the selectivity of deep oxidation product CO2is less than 5%.

Claims

1. A core-shell boron-based catalyst for methane oxidative coupling, characterized in that: The catalyst has a core-shell structure, with the active component B2O3 as the shell and the metal oxide additive MO supported by the carrier Z. x As the core, its chemical formula can be expressed as MO x / Z@B2O3; among them, metal oxide additive MO x By CoO x or NiO x One or a combination of two.

2. The core-shell boron-based catalyst for methane oxidative coupling according to claim 1, wherein The carrier Z is composed of one or a combination of BN, SiO2, TiO2, Al2O3, ZnO, MgO, ZrO2, CeO2, GaO2, InO2 or molecular sieves.

3. A method for preparing a core-shell boron-based catalyst for methane oxidative coupling according to claim 1, characterized in that: The specific steps are as follows: (1) Loading of metal oxide additives: dissolve the metal precursor salt in a solvent, then add the carrier and stir, heat and evaporate the resulting mixture, dry the resulting solid and then calcine it to obtain MO x / Z precursor; (2) Activation of metal oxide additives: Activate the MO prepared in step (1) x The / Z precursor is added to an organic solvent for solvothermal reaction, and the collected solid is washed and dried and then calcined to obtain activated MO x / Z precursor; (3) Coating of active component B2O3: The activated MO prepared in step (2) x The precursor is added to a boric acid solution and stirred, the resulting mixture is heated and evaporated to dryness, and the resulting solid is dried and then calcined.

4. The method for preparing a core-shell boron-based catalyst for methane oxidative coupling according to claim 3, wherein: The metal precursor salt described in step (1) is composed of one or a combination of cobalt chloride, cobalt oxalate, cobalt sulfate, cobalt nitrate, cobalt acetate, nickel nitrate, nickel sulfate, nickel chloride, nickel sulfamate or nickel bromide.

5. The method for preparing a core-shell boron-based catalyst for methane oxidative coupling according to claim 3, wherein: The solvent in step (1) is composed of one or more of water, ethanol or acetone.

6. The method for preparing a core-shell boron-based catalyst for methane oxidative coupling according to claim 3, wherein: The solvent thermal reaction conditions described in step (2) are: the reaction atmosphere is an inert atmosphere, the reaction temperature is 100-300°C, the reaction pressure is 0.1-3 MPa, and the reaction time is 1-24 h.

7. The method for preparing a core-shell boron-based catalyst for methane oxidative coupling according to claim 3, wherein: The calcination conditions are as follows: the calcination atmosphere is air, the calcination temperature is 300-800° C., and the calcination time is 1-10 hours.

8. A core-shell boron-based catalyst for methane oxidative coupling according to any one of claims 1 to 2 or a catalyst prepared by the preparation method according to any one of claims 3 to 7 in catalyzing the methane oxidative coupling reaction to prepare C 2+ Application in hydrocarbon compounds, characterized in that, The specific steps include: The oxidative coupling of methane with a core-shell boron-based catalyst MO x / Z@B2O3 is loaded into a continuous flow reaction device, heated, activated in an oxygen-containing atmosphere, and then raw methane and oxygen are introduced to carry out a methane oxidative coupling catalytic reaction; wherein, the reaction temperature is 400-800°C, the heating rate is 5-10°C / min, the total flow rate of the reaction gas is 10-100 mL / min, the partial pressure of CH4 is 10-80 kPa, the partial pressure of O2 is 10-80 kPa, and the total reaction pressure is atmospheric pressure.

9. The methane oxidative coupling core-shell boron-based catalyst according to claim 8 is used to catalyze the methane oxidative coupling reaction to prepare C 2+ Application in hydrocarbon compounds, characterized in that, The activation time is 0.5 to 3 hours, and the activation temperature is 400 to 800°C.

10. The methane oxidative coupling core-shell boron-based catalyst according to claim 8 is used to catalyze the methane oxidative coupling reaction to prepare C 2+ Application in hydrocarbon compounds, characterized in that, The continuous flow reaction device is selected from a fixed bed reactor or a moving bed reactor.

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