Lanthanum oxide with methane oxidative coupling function and preparation method and application thereof

Abstract

The invention relates to the technical field of methane oxidative coupling, and discloses lanthanum oxide with a methane oxidative coupling function and a preparation method and application thereof, the pore diameter of the lanthanum oxide is in bimodal distribution, the first most probable pore diameter is 20-50 angstroms, and the second most probable pore diameter is 50-1000 angstroms. The preparation method of lanthanum oxide comprises the steps that a solid material and alkali liquor are mixed to obtain a mixed material, then the mixed material is subjected to solid-liquid separation to obtain a solid-phase product, the solid-phase product is roasted, and the solid material comprises lanthanum salt. When the lanthanum oxide is used for the oxidative coupling reaction of methane, the selectivity of hydrocarbon with two or more carbon atoms can be remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of methane oxidative coupling, and in particular to lanthanum oxide with methane oxidative coupling function, and a preparation method and application thereof. Background Art

[0002] Natural gas is an energy source that has received much attention in recent years due to the development of new development methods. Shale gas deposits are distributed all over the world, mainly in Asia, Europe, North America and Latin America, with China and Argentina being the countries with the largest reserves of natural gas. Therefore, the reaction of converting methane and natural gas into ethylene ethane through the oxidative coupling of methane (OCM) is of great importance. The OCM reaction was first reported by Keller and Bahsin in 1982. Their work showed that this reaction is more thermodynamically favorable than direct methane conversion. The OCM reaction produces methyl radicals through the oxidative dehydrogenation of methane molecules, which couple with each other to form ethane and ethylene. In the 1990s, despite the great efforts of scientists to work on the OCM reaction, the yields that should be achieved for acceptable industrial applications were still not achieved. However, some progress has been made in the study of the reaction mechanism and activity, and methane dehydrogenation and methyl radical coupling are considered to be the basic reaction steps. As mentioned above, in the past few years, the research interest in the OCM reaction has further increased, and catalysts with higher activity and selectivity have been continuously discovered. It is worth noting that the OCM reaction is a highly exothermic reaction, and hot spots are easily generated in the reactor. If the selectivity of the product is high enough, the strong exotherm of the reaction process can be effectively reduced. Rare earth oxides and their composite catalysts with alkaline earth metals have high catalytic activity and selectivity for methane oxidative coupling reaction, and also show good stability at high temperatures. CN109663587A prepares a nanoflower-like lanthanum oxide catalyst. The document Structure Sensitivity of La2O2CO3 Catalysts in theOxidative Coupling of Methane, ACS Catal. 2015, 5, 1663-1674 reports that different preparation methods have different methane oxidative coupling reaction performances. In order to further improve the catalytic performance of lanthanum oxide catalysts, the present invention prepares lanthanum oxide catalysts, and applies the catalysts to methane oxidative coupling reaction and achieves unexpected results. Summary of the invention

[0003] The purpose of the present invention is to improve the selectivity of carbon two and above hydrocarbons, and to provide a lanthanum oxide with methane oxidative coupling function and a preparation method and application thereof.

[0004] In order to achieve the above object, the first aspect of the present invention provides a lanthanum oxide with methane oxidative coupling function, wherein the pore size of the lanthanum oxide is bimodal, the first most probable pore size is 20-50 angstroms, and the second most probable pore size is 50-1000 angstroms.

[0005] The second aspect of the present invention provides a method for preparing lanthanum oxide with methane oxidative coupling function, the method comprising: mixing a solid material with an alkali solution to obtain a mixed material, then performing solid-liquid separation on the mixed material to obtain a solid phase product, and roasting the solid phase product, wherein the solid material comprises a lanthanum salt.

[0006] The third aspect of the present invention provides lanthanum oxide prepared by the method described above.

[0007] A fourth aspect of the present invention provides an application of the lanthanum oxide described above in the oxidative coupling reaction of methane to produce C2 and higher hydrocarbons.

[0008] A fifth aspect of the present invention provides a method for preparing hydrocarbons having two or more carbon atoms from methane, the method comprising: contacting and reacting methane with the above-mentioned lanthanum oxide in the presence of oxygen and under the conditions of methane oxidative coupling reaction;

[0009] Alternatively, lanthanum oxide is prepared according to the method described above, and then methane is contacted with the obtained lanthanum oxide in the presence of oxygen and under the conditions of methane oxidative coupling reaction.

[0010] The present invention prepares lanthanum oxide with bimodal pore size distribution by mixing solid materials of lanthanum salt with alkali solution. When the lanthanum oxide is used in methane oxidative coupling reaction, the selectivity of C2 and above hydrocarbons can be significantly improved.

[0011] Preferably, a mixed solid material of lanthanum salt and doping element compound is mixed with an alkali solution to prepare lanthanum oxide with a bimodal pore size distribution, which can further improve the selectivity of C2 and above hydrocarbons.

[0012] Preferably, the lanthanum oxide prepared by the present invention has a columnar structure, and more preferably, has a specific ratio of column length to column width, which can further improve the selectivity of C2 and above hydrocarbons. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a scanning electron microscope image of lanthanum oxide prepared in Example 1;

[0014] Figure 2 is a pore size distribution diagram of lanthanum oxide prepared in Example 1;

[0015] Figure 3 is a scanning electron microscope image of lanthanum oxide prepared in Comparative Example 1;

[0016] Figure 4This is the pore size distribution diagram of lanthanum oxide prepared in Comparative Example 1. DETAILED DESCRIPTION

[0017] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0018] The first aspect of the present invention provides a lanthanum oxide having a methane oxidative coupling function, wherein the pore size of the lanthanum oxide is bimodal, the first most probable pore size is 20-50 angstroms, and the second most probable pore size is 50-1000 angstroms.

[0019] In the present invention, It is a unit of length, 10 angstroms = 1 nm.

[0020] In the present invention, the first most probable pore size can be 20 angstroms, 25 angstroms, 30 angstroms, 35 angstroms, 40 angstroms, 45 angstroms, 50 angstroms, and a range consisting of any two of the above points. The second most probable pore size can be 50 angstroms, 100 angstroms, 200 angstroms, 300 angstroms, 400 angstroms, 450 angstroms, 490 angstroms, 495 angstroms, 500 angstroms, 505 angstroms, 510 angstroms, 550 angstroms, 600 angstroms, 700 angstroms, 800 angstroms, 900 angstroms, 1000 angstroms, and a range consisting of any two of the above points.

[0021] According to the present invention, preferably, the percentage of the pore volume of pores with a pore diameter in the range of 20-50 angstroms in the lanthanum oxide to the total pore volume is 1-5% (for example, 1%, 2%, 3%, 4%, 5%, and the range composed of any two of the above points), preferably 1-4%.

[0022] According to the present invention, preferably, the pore size of the lanthanum oxide is bimodal, the first most probable pore size is 20-35 angstroms, and the second most probable pore size is 400-600 angstroms. When the first most probable pore size and the second most probable pore size are within the above preferred range, the selectivity of C2 and above hydrocarbons can be further improved.

[0023] According to the present invention, preferably, the lanthanum oxide is columnar, and the column length is 0.1-1 μm (for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, and a range formed by any two of the above points); more preferably, the column length is 0.1-0.6 μm; further preferably, the column length is 0.4-0.6 μm.

[0024] According to the present invention, preferably, the lanthanum oxide is columnar, and the column width is 10-120nm (for example, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, and a range consisting of any two of the above points); more preferably, the column width is 30-100nm.

[0025] According to the present invention, preferably, the ratio of column length to column width is 5-30:1 (for example, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, 25:1, 30:1, and the range formed by any two of the above points); more preferably, the ratio of column length to column width is 5-20:1.

[0026] According to the present invention, preferably, the specific surface area of ​​the lanthanum oxide is 30-80 m 2 / g, more preferably 45-50m 2 / g.

[0027] According to the present invention, preferably, the pore volume of the lanthanum oxide is 0.2-0.6 cm 3 / g, more preferably, 0.25-0.3cm 3 / g.

[0028] According to the present invention, preferably, the average pore size of the lanthanum oxide is 200-270 angstroms, more preferably 240-250 angstroms. It is a unit of length, 10 angstroms = 1 nm.

[0029] According to the present invention, preferably, the lanthanum oxide further contains a doping element, and the doping element includes at least one of barium, strontium, magnesium and iron.

[0030] According to the present invention, preferably, the molar ratio of lanthanum element to doping element in the lanthanum oxide is 1:0.01-0.9 (for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, and the range of any two of the above points), more preferably 1:0.3-0.7. In the present invention, the molar ratio of lanthanum element to doping element in lanthanum oxide is calculated according to the feed amount.

[0031] The second aspect of the present invention provides a method for preparing lanthanum oxide with methane oxidative coupling function, the method comprising: mixing a solid material with an alkali solution to obtain a mixed material, then performing solid-liquid separation on the mixed material to obtain a solid phase product, and roasting the solid phase product, wherein the solid material comprises a lanthanum salt.

[0032] The inventors of the present invention unexpectedly discovered that lanthanum oxide with a bimodal pore size distribution can be prepared by mixing a lanthanum salt in a solid form with an alkaline solution for reaction, and the lanthanum oxide can significantly improve the selectivity of C2 and above hydrocarbons when used in methane oxidative coupling.

[0033] According to the present invention, preferably, the lanthanum salt includes at least one of lanthanum nitrate, lanthanum acetate and lanthanum chloride.

[0034] According to the present invention, preferably, the solid material further comprises a substance containing a doping element; more preferably, the substance containing a doping element comprises at least one of barium nitrate, strontium nitrate, magnesium nitrate and iron nitrate.

[0035] According to the present invention, preferably, the molar ratio of the lanthanum salt to the substance containing the doping element is 1:0.01-0.9.

[0036] According to the present invention, preferably, the alkaline solution is a solution of an alkali metal hydroxide, more preferably a potassium hydroxide solution and / or a sodium hydroxide solution.

[0037] In the present invention, the solvent in the alkali solution is usually water, and the alkali solution is usually an aqueous solution of alkali metal sodium hydroxide. According to the present invention, preferably, the concentration of the alkali solution is 1-3 mol / L, more preferably 2-3 mol / L.

[0038] According to the present invention, preferably, the weight ratio of the lanthanum salt to the alkali solution is 1:2-120, more preferably 1:10-100, and further preferably 1:50-100. The weight ratio of the lanthanum salt to the alkali solution can be 1:2, 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, and a range consisting of any two of the above.

[0039] According to the present invention, in order to further improve the selectivity of C2 and above hydrocarbons, preferably, the solid-liquid separation method includes: after the mixed material is allowed to stand for a first time, the upper clear liquid is removed, water is added, and then a second standing is performed, and then a solid phase product is obtained by centrifugal separation.

[0040] According to the present invention, preferably, the first standing time is 10-100 hours.

[0041] According to the present invention, preferably, the second standing time is 12-24 hours.

[0042] According to the present invention, preferably, the first standing and the second standing are each independently carried out at 5-80°C (for example, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 40°C, 50°C, 60°C, 80°C, and a range consisting of any two of the above points); more preferably, the first standing and the second standing are each independently carried out at 5-20°C.

[0043] According to the present invention, preferably, the weight ratio of water to lanthanum salt is 40-100:1, for example, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, and a range consisting of any two of the above. More preferably, the weight ratio of water to lanthanum salt is 50-95:1.

[0044] According to the present invention, preferably, the method further comprises a drying step before calcination, and the drying conditions include: a temperature of 80-120° C. and a time of 12-24 hours.

[0045] According to the present invention, preferably, the calcination conditions include: a temperature of 700-800°C and a time of 2-10h; more preferably, the temperature is increased to the calcination temperature at a heating rate of 2-5°C / min.

[0046] The third aspect of the present invention provides lanthanum oxide prepared by the method described above.

[0047] A fourth aspect of the present invention provides the use of the above-mentioned lanthanum oxide in the oxidative coupling reaction of methane to produce C2 and higher hydrocarbons.

[0048] A fifth aspect of the present invention provides a method for preparing hydrocarbons having two or more carbon atoms from methane, characterized in that the method comprises: in the presence of oxygen and under the conditions of methane oxidative coupling reaction, contacting methane with the above-mentioned lanthanum oxide for reaction;

[0049] Alternatively, lanthanum oxide is prepared according to the method described above, and then methane is contacted with the obtained lanthanum oxide in the presence of oxygen and under the conditions of methane oxidative coupling reaction.

[0050] According to the present invention, preferably, the molar ratio of the methane to the oxygen (referred to as the alkoxygen ratio) is 2-10:1.

[0051] According to the present invention, preferably, the temperature of the contact reaction is 700-850°C.

[0052] According to the present invention, preferably, the space velocity of methane is 5000-150000 mL / (g·h).

[0053] According to a particularly preferred embodiment of the present invention, the preparation method of lanthanum oxide comprises: weighing 6-6.5g of lanthanum nitrate hexahydrate and 1.1-1.2g of barium nitrate, adding 280-300g of sodium hydroxide aqueous solution (2.5-3mol / L), quickly stirring evenly, standing at 8-12°C for 90-100h, pouring out the supernatant, adding 280-300g of deionized water, stirring evenly and standing at 8-12°C for 20-24h, washing with water and ethanol with a centrifuge, keeping at 110-120°C for 10-12h, and then heating to 740-750°C at 2-2.5°C / min in an air atmosphere and keeping for 2-2.5h to prepare a lanthanum oxide catalyst.

[0054] The present invention will be described in detail below by way of examples. In the following examples,

[0055] The room temperature is 25°C.

[0056] The calculation method of methane conversion rate is as follows:

[0057] Methane conversion rate = amount of methane consumed in the reaction / initial amount of methane × 100%.

[0058] The ethylene selectivity is calculated as follows:

[0059] Ethylene selectivity = amount of methane consumed by produced ethylene / total methane consumption x 100%.

[0060] The ethane selectivity is calculated as follows:

[0061] Ethane selectivity = amount of methane consumed by produced ethane / total methane consumption x 100%.

[0062] The selectivity of C2 and above hydrocarbons includes the sum of ethylene, ethane, propylene, propane and higher carbon hydrocarbons.

[0063] Example 1

[0064] Weigh 6g of lanthanum nitrate hexahydrate and 1.2g of barium nitrate, add 300g of sodium hydroxide aqueous solution (3mol / L), stir quickly and evenly, let stand at 10°C for 100h, pour off the supernatant, add 300g of deionized water, stir evenly and let stand at 10°C for 24h, wash and separate with a centrifuge, wash three times with water, wash once with ethanol, place in an oven, 120°C, keep for 12h, then move to a muffle furnace, heat to 750°C at 2°C / min in an air atmosphere, and keep for 2h. Lanthanum oxide catalyst A1 is prepared.

[0065] The scanning electron microscope (SEM) and pore size distribution diagram of lanthanum oxide catalyst A1 are shown in Figure 2. Figure 1 and Figure 2 As shown by Figure 1It can be seen that lanthanum oxide is columnar and has a short and thick columnar structure with uniform length and height. Figure 2 It can be seen that the pore size of lanthanum oxide is bimodal, and the pore size of most pores is distributed in the range of 100-1000 angstroms.

[0066] Example 2

[0067] Weigh 3.5g of lanthanum nitrate hexahydrate and 1.1g of strontium nitrate, add 350g of sodium hydroxide aqueous solution (2mol / L), stir quickly and evenly, let stand at 15°C for 50h, pour off the supernatant, add 325g of deionized water, stir evenly and let stand at 15°C for 12h, wash and separate with a centrifuge, wash three times with water, wash once with ethanol, place in an oven, 120°C, keep for 12h, then move to a muffle furnace, heat to 700°C at 2°C / min in an air atmosphere, and keep for 5h. Lanthanum oxide catalyst A2 is prepared.

[0068] Example 3

[0069] Weigh 2.5g of lanthanum nitrate hexahydrate and 1g of strontium nitrate, add 100g of sodium hydroxide aqueous solution (1mol / L), stir quickly and evenly, let stand at 5°C for 10h, pour off the supernatant, add 100g of deionized water, stir evenly and let stand at 5°C for 24h, wash and separate with a centrifuge, wash three times with water and once with ethanol, place in an oven at 120°C, keep for 12h, then move to a muffle furnace, heat to 800°C at 5°C / min in an air atmosphere, and keep for 2h. Lanthanum oxide catalyst A3 is prepared.

[0070] Example 4

[0071] The method of Example 1 was followed, except that barium nitrate was replaced by an equal molar amount of iron nitrate.

[0072] Example 5

[0073] The method of Example 1 was followed, except that the amount of barium nitrate used was 0.1 g.

[0074] Example 6

[0075] The method of Example 1 was followed, except that the barium nitrate was replaced with an equal molar amount of lanthanum nitrate hexahydrate.

[0076] Example 7

[0077] The method of Example 1 was followed, except that the standing temperature was 60°C.

[0078] Comparative Example 1

[0079] Weigh 3.5g of lanthanum nitrate hexahydrate and 1.1g of strontium nitrate, add 350g of deionized water, add sodium hydroxide aqueous solution (2mol / L) dropwise, adjust the end point pH value to 11, stir evenly and let stand at room temperature for 12h, wash and separate with a centrifuge, wash three times with water, wash once with ethanol, place in an oven, 120°C, keep for 12h, then move to a muffle furnace, heat to 700°C at 2°C / min in an air atmosphere, and keep for 5h. Lanthanum oxide catalyst D1 is prepared.

[0080] The scanning electron microscope (SEM) and pore size distribution diagram of lanthanum oxide catalyst D1 are shown in Figure 2. Figure 3 and Figure 4 As shown by Figure 3 It can be seen that the prepared lanthanum oxide is rod-shaped and has relatively poor length uniformity. Figure 4 It can be seen that the pore size is unimodal.

[0081] Test Example 1

[0082] The shape and size, specific surface area, pore volume, average pore diameter, most probable pore diameter and other results of the above lanthanum oxide catalyst are shown in Table 1.

[0083] The shape of the lanthanum oxide catalyst is determined by scanning electron microscopy. The test method for the size of the lanthanum oxide catalyst is as follows: 5-10 samples in the field of view are selected, and the column length and column width are measured using the measuring instrument provided by the scanning electron microscope, and then the average column length and column width of the 5-10 samples in the field of view are calculated as the column length and column width data of the samples, and the ratio of the column length to the column width is calculated based on the average column length and average column width of the samples.

[0084] The test method for the specific surface area, pore volume, average pore size and most probable pore size of the lanthanum oxide catalyst is as follows: weigh a certain mass of sample and put it into a sample tube, put the sample tube into the instrument degassing station, degassing treatment, the degassing condition is 350 degrees for 4 hours, and after natural cooling to room temperature, the sample tube is put into the instrument analysis station for analysis, and the nitrogen adsorption and desorption isotherm is fully analyzed at liquid nitrogen temperature. The specific surface area of ​​the sample is calculated by the BET (Brunauer, Emmett, Teller) method, and the pore volume and average pore size of the sample are calculated by the BJH (Barret, Joyner, Halenda) method according to the desorption (adsorption) branch.

[0085] Table 1

[0086]

[0087] Note: “V 20-50 / V 总 The term “percentage” refers to the percentage of the pore volume occupied by pores with a pore diameter range of 20-50 angstroms to the total pore volume.

[0088] Test Example 2

[0089] After the catalyst tablets were sieved through 40-60 mesh, 100 mg was weighed and loaded into a quartz tube fixed bed reactor with an inner diameter of 4 mm, and methane and oxygen were introduced, with a methane space velocity of 140000 mL / (g·h), an alkoxy ratio of 8, and a reaction temperature of 750°C. The product composition was detected online by Agilent gas chromatography, and the results are shown in Table 2.

[0090] Table 2

[0091]

[0092]

[0093] It can be seen from the results in Table 2 that the lanthanum oxide prepared by the method of the present invention has a high selectivity for C2 and above hydrocarbons. Particularly preferably, the lanthanum oxide prepared by the method of Examples 1-2 of the present invention can further improve the selectivity for C2 and above hydrocarbons.

[0094] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A lanthanum oxide having methane oxidative coupling function, characterized in that: The pore size of the lanthanum oxide is bimodal, with a first most probable pore size of 20-50 angstroms and a second most probable pore size of 50-1000 angstroms.

2. The lanthanum oxide according to claim 1, wherein The percentage of the pore volume of the pores with a pore diameter of 20-50 angstroms in the lanthanum oxide to the total pore volume is 1-5%, preferably 1-4%; And / or, the pore size of the lanthanum oxide is bimodal, with a first most probable pore size of 20-35 angstroms and a second most probable pore size of 400-600 angstroms; And / or, the lanthanum oxide is columnar, with a column length of 0.1-1 μm, a column width of 10-120 nm, and a ratio of column length to column width of 5-30:1; preferably, the column length is 0.1-0.6 μm, the column width is 30-100 nm; the ratio of column length to column width is 5-20:1; And / or, the specific surface area of ​​the lanthanum oxide is 30-80m 2 / g, pore volume is 0.2-0.6cm 3 / g, and the average pore size is 200-270 angstroms.

3. The lanthanum oxide according to claim 1, wherein The lanthanum oxide further contains a doping element, and the doping element includes at least one of barium, strontium, magnesium and iron; Preferably, the molar ratio of lanthanum element to doping element in the lanthanum oxide is 1:0.01-0.

9.

4. A method for preparing lanthanum oxide having methane oxidative coupling function, characterized in that: The method comprises: mixing a solid material with an alkaline solution to obtain a mixed material, performing solid-liquid separation on the mixed material to obtain a solid phase product, and roasting the solid phase product, wherein the solid material comprises a lanthanum salt.

5. The method according to claim 4, wherein: The lanthanum salt comprises at least one of lanthanum nitrate, lanthanum acetate and lanthanum chloride; And / or, the solid material further comprises a substance containing a doping element; preferably, the substance containing a doping element comprises at least one of barium nitrate, strontium nitrate, magnesium nitrate and iron nitrate; And / or, the molar ratio of the lanthanum salt to the substance containing the doping element is 1:0.01-0.

9.

6. The method according to claim 4, wherein: The alkali solution is potassium hydroxide solution and / or sodium hydroxide solution; And / or, the concentration of the alkali solution is 1-3 mol / L; And / or, the weight ratio of the lanthanum salt to the alkali solution is 1:2-120, preferably 1:10-100.

7. The method according to claim 4, wherein: The solid-liquid separation method includes: the mixed material is first allowed to stand, the upper clear liquid is removed, water is added, and then the mixed material is allowed to stand for a second time, and then centrifugally separated to obtain a solid phase product; Preferably, the first standing time is 10-100h; Preferably, the second standing time is 12-24h; Preferably, the first standing and the second standing are each independently performed at 5-80°C; Preferably, the weight ratio of water to lanthanum salt is 40-100:

1.

8. The method according to claim 4, wherein: The method further comprises a drying step before calcination, wherein the drying conditions include: a temperature of 80-120° C. and a time of 12-24 hours; And / or, the calcination conditions include: a temperature of 700-800° C. and a time of 2-10 h; preferably, the temperature is increased to the calcination temperature at a heating rate of 2-5° C. / min.

9. Lanthanum oxide prepared by the method described in any one of claims 4 to 8.

10. Use of the lanthanum oxide described in any one of claims 1 to 3 and 9 in the oxidative coupling reaction of methane to produce C2 and higher hydrocarbons.

11. A method for preparing hydrocarbons with carbon content of two or more carbon atoms from methane, characterized in that: The method comprises: in the presence of oxygen and under the conditions of methane oxidative coupling reaction, contacting methane with the lanthanum oxide described in any one of claims 1 to 3 and 9 for reaction; Alternatively, lanthanum oxide is prepared according to the method according to any one of claims 4 to 8, and then methane is contacted with the obtained lanthanum oxide to react in the presence of oxygen and under the conditions of methane oxidative coupling reaction.

12. The method according to claim 11, wherein: The molar ratio of the methane to the oxygen is 2-10:1; And / or, the temperature of the contact reaction is 700-850°C; And / or, the space velocity of methane is 5000-150000 mL / (g·h).

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