Methane oxidation coupling catalyst, method for preparing the same, and method for preparing ethane and ethylene from methane

Abstract

This invention relates to the field of methane oxidative coupling technology, and discloses a methane oxidative coupling catalyst, its preparation method, and a method for preparing ethane and ethylene from methane. The catalyst comprises lanthanum oxycarbonate and a modifying agent supported on lanthanum oxycarbonate; wherein the lanthanum oxycarbonate exists in the form of rod-shaped particles, the length of which is 30-500 nm, the diameter of which is 5-50 nm, and the specific surface area of ​​which is 50-100 m². 2 / g; the modifying agent is a modified element oxide, and the modifying element is selected from one or more of Cs, Ce, Fe, B, Zn, Cd, and Ni; in the catalyst, the molar ratio of lanthanum to the modifying element is 1-100:1. The methane oxidative coupling catalyst provided by this invention has high activity in the methane oxidative coupling reaction under reaction conditions of 450-650℃, and the selectivity of ethylene and ethane in the product is good, showing good application prospects.

Description

Technical Field

[0001] This invention relates to the field of catalysts, specifically to a methane oxidative coupling catalyst, a method for preparing the same, and a method for preparing ethane and ethylene from methane. Background Technology

[0002] Methane oxidative coupling is an exothermic reaction, and the main products are ethylene, ethane and water. This technology has the characteristics of good atom economy and environmental friendliness. Since Keller and Bhasin published their paper in 1982, it has been a focus of attention in the fields of catalysis, chemical industry and oil and gas.

[0003] Lanthanum oxycarbonate is currently a commonly used catalyst for the oxidative coupling reaction of methane. Lanthanum oxycarbonate exhibits various nanostructures, such as rod-shaped, plate-shaped, flower-shaped, and spherical. Studies have shown that rod-shaped lanthanum oxycarbonate possesses good low-temperature activity; however, it has a relatively small specific surface area, fewer active sites, and uneven promoter distribution, requiring further improvement. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of small specific surface area of ​​rod-shaped lanthanum oxycarbonate, and to provide a methane oxidative coupling catalyst, its preparation method, and a method for preparing ethane and ethylene from methane.

[0005] To achieve the above objectives, a first aspect of the present invention provides a methane oxidative coupling catalyst, the catalyst comprising lanthanum oxycarbonate and a modifying agent supported on lanthanum oxycarbonate; wherein the lanthanum oxycarbonate exists in the form of rod-shaped particles, the rod-shaped particles having a length of 30-500 nm, a diameter of 5-50 nm, and a specific surface area of ​​50-100 m². 2 / g; the modifying agent is a modified element oxide, and the modifying element is selected from one or more of Cs, Ce, Fe, B, Zn, Cd, and Ni; in the catalyst, the molar ratio of lanthanum to the modifying element is 1-100:1.

[0006] A second aspect of the present invention provides a method for preparing a methane oxidative coupling catalyst, the method comprising the following steps:

[0007] (1) Add the alkaline solution to a solution containing soluble lanthanum salt and react under ultrasonic conditions to obtain a mixture containing precipitate; wherein the ultrasonication is performed at room temperature and the ultrasonication operation conditions include first ultrasonication at 20-30 kHz for 1-5 h, then ultrasonication at 40-60 kHz for 1-5 h, and then ultrasonication at 80-120 kHz for 0.5-2 h.

[0008] (2) Under normal pressure, the mixture containing the precipitate is aged at 25-75°C to obtain lanthanum hydroxide;

[0009] (3) The lanthanum hydroxide is mixed with a solution containing a modified auxiliary agent precursor and then impregnated to obtain an impregnated product; wherein the modified auxiliary agent precursor is selected from one or more soluble compounds containing Cs, Ce, Fe, B, Zn, Cd and Ni elements;

[0010] (4) The impregnated product is calcined at 400-600°C to obtain the methane oxidative coupling catalyst.

[0011] A third aspect of the present invention provides a method for preparing ethane and ethylene from methane, the method comprising: in the presence of an oxygen-containing gas, contacting methane with the methane oxidative coupling catalyst described in the first aspect of the present invention or the catalyst prepared by the preparation method described in the second aspect of the present invention to carry out a methane oxidative coupling reaction, thereby obtaining ethane and ethylene.

[0012] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0013] 1) The methane oxidative coupling catalyst provided by the present invention has high methane oxidative coupling reaction activity under reaction conditions of 450-650℃, and the selectivity of ethylene and ethane in the product is good.

[0014] 2) The preparation method of the methane oxidative coupling catalyst provided by the present invention, with the combined action of frequency conversion ultrasonic treatment and low concentration of alkaline solution, helps to obtain slender rod-shaped lanthanum oxycarbonate, which can further improve the specific surface area of ​​rod-shaped lanthanum oxycarbonate.

[0015] 3) The method for preparing the methane oxidative coupling catalyst provided by the present invention can be aged under normal pressure by frequency conversion ultrasonic treatment and the addition of modifying agents to obtain a catalyst with high catalytic activity and good selectivity. This eliminates the step of hydrothermal reaction in a hydrothermal reactor, which can reduce the preparation cost and has good application prospects. Attached Figure Description

[0016] Figure 1 This is a scanning electron microscope image of lanthanum hydroxide prepared in Example 1 of the present invention.

[0017] Figure 2 This is a scanning electron microscope image of the methane oxidative coupling catalyst A-1 prepared in Example 1 of the present invention. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] A first aspect of the present invention provides a methane oxidative coupling catalyst, the catalyst comprising lanthanum oxycarbonate and a modifying agent supported on lanthanum oxycarbonate; wherein the lanthanum oxycarbonate exists in the form of rod-shaped particles, the rod-shaped particles having a length of 30-500 nm, a diameter of 5-50 nm, and a specific surface area of ​​50-100 m². 2 / g; the modifying agent is a modified element oxide, and the modifying element is selected from one or more of Cs, Ce, Fe, B, Zn, Cd, and Ni; in the catalyst, the molar ratio of lanthanum to the modifying element is 1-100:1.

[0020] In a preferred embodiment, the length of the rod-shaped particle refers to the straight-line distance between the two longest endpoints of the lanthanum oxycarbonate rod-shaped particle, which can be determined by measuring the scale of a scanning electron microscope. Since the dimensions of the rod-shaped particles remain essentially unchanged before and after loading the modifying agent, the length and diameter of the lanthanum oxycarbonate rod-shaped particles in this invention are the length and diameter of the catalyst particles after loading the modifying agent. The length of the rod-shaped particles in this invention can be any value between 30-400 nm, for example, 30 nm, 40 nm, 50 nm, 80 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm, 225 nm, 250 nm, 275 nm, 300 nm, 325 nm, 350 nm, 375 nm, 400 nm, 450 nm, 500 nm, and any value within any two of the above values, preferably 200-350 nm, and more preferably 300-350 nm.

[0021] In a preferred embodiment, the diameter of the rod-shaped particles can be any value between 5 and 50 nm, for example, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 33 nm, 35 nm, 37 nm, 40 nm, 45 nm, 50 nm, and any value within the range formed by any two of the above values, preferably 10-30 nm, and more preferably 10-25 nm.

[0022] In a preferred embodiment, the specific surface area of ​​the rod-shaped particles can be 50-100 m². 2 Any value between / g, for example, 50m 2 / g、52m 2 / g、54m 2 / g、56m 2 / g、58m 2 / g、60m 2 / g、62m 2 / g、64m 2 / g、66m 2 / g、68m 2 / g、70m 2 / g、72m 2 / g、74m 2 / g、76m 2 / g、78m 2 / g、80m 2 / g、85m 2 / g、90m 2 / g、95m 2 / g, 100m 2 / g, and any value within the range formed by any two of the above values, preferably 55-85m. 2 / g, further preferably 70-80m 2 / g.

[0023] In this invention, since the specific surface area of ​​the rod-shaped lanthanum oxycarbonate particles remains essentially unchanged before and after loading the modified additive, the specific surface area of ​​the rod-shaped particles in this invention is the same as the specific surface area of ​​the catalyst particles after loading the modified additive.

[0024] In a preferred embodiment, the modifying element is selected from one or more of Cs, Ce, Fe, and Ni, and more preferably Cs and / or Ce.

[0025] In a preferred embodiment, the molar ratio of lanthanum to the modifying element in the catalyst can be any ratio between 1 and 100:1, such as 1:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, 100:1, and any two of the above ratios forming a range, preferably 10-60:1.

[0026] The methane oxidative coupling catalyst provided by this invention exhibits high activity in the methane oxidative coupling reaction under reaction conditions of 450-650℃, and the selectivity of ethylene ethane in the product is good.

[0027] A second aspect of the present invention provides a method for preparing a methane oxidative coupling catalyst, the method comprising the following steps:

[0028] (1) Add the alkaline solution to a solution containing soluble lanthanum salt and react under ultrasonic conditions to obtain a mixture containing precipitate; wherein the ultrasonication is carried out at room temperature, and the ultrasonication operation conditions include first ultrasonication at 20-30 kHz for 1-5 h, then ultrasonication at 40-60 kHz for 1-5 h; and then ultrasonication at 80-120 kHz for 0.5-2 h.

[0029] (2) Under normal pressure, the mixture containing the precipitate is aged at 25-75°C to obtain lanthanum hydroxide;

[0030] (3) The lanthanum hydroxide is mixed with a solution containing a modified auxiliary agent precursor and then impregnated to obtain an impregnated product; wherein the modified auxiliary agent precursor is selected from one or more soluble compounds containing Cs, Ce, Fe, B, Zn, Cd and Ni elements.

[0031] (4) The impregnated product is calcined at 400-600°C to obtain the methane oxidative coupling catalyst.

[0032] The inventors of this invention have discovered through research that, compared to commercially available lanthanum hydroxide, the method described in this invention can produce slender, rod-shaped lanthanum hydroxide particles. Variable frequency ultrasonic treatment can increase the specific surface area of ​​the rod-shaped lanthanum hydroxide. By adding modifying agents to the rod-shaped lanthanum hydroxide, a methane oxidative coupling catalyst capable of maintaining high activity at low temperatures can be prepared.

[0033] In step (1):

[0034] In a preferred embodiment, the alkaline solution is an aqueous solution of an alkali, wherein the alkali in the alkaline solution is selected from sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide.

[0035] In a preferred embodiment, the concentration of alkali in the alkaline solution is 5-12% by weight, more preferably 10-12% by weight. The inventors of this invention have discovered that using a low-concentration alkaline solution helps to obtain slender rod-shaped lanthanum oxycarbonate, which can further increase the specific surface area of ​​the rod-shaped lanthanum oxycarbonate.

[0036] In a preferred embodiment, the present invention does not specifically limit the soluble lanthanum salt, and commonly used soluble lanthanum salts in the art can be used in the present invention. For example, the soluble lanthanum salt may include, but is not limited to, lanthanum acetate, lanthanum chlorate, and lanthanum nitrate.

[0037] In a preferred embodiment, the concentration of lanthanum in the solution containing the soluble lanthanum salt is 0.05-10% by weight, more preferably 0.1-5% by weight.

[0038] In a preferred embodiment, the mass ratio of the alkaline solution to the solution containing the soluble lanthanum salt is 1:5-20, more preferably 1:10-15.

[0039] In a preferred embodiment, the present invention does not impose any particular limitation on the method of adding the alkaline solution to the solution containing soluble lanthanum salt; it can be added all at once, in batches, or dropwise, but is preferably added all at once.

[0040] In a preferred embodiment, the ultrasound is performed at room temperature. The ultrasound operating conditions include first ultrasound at 26-28 kHz for 2-3 hours, then ultrasound at 45-50 kHz for 2-3 hours, followed by ultrasound at 90-110 kHz for 1.5-2 hours. The present invention does not specifically limit the room temperature, which can be 15-35°C.

[0041] In this invention, the inventors discovered through research that increasing the frequency difference between the three-stage variable frequency ultrasonic waves can further promote the reaction between low-concentration alkaline solution and lanthanum salt, thereby increasing the specific surface area of ​​the resulting lanthanum oxycarbonate.

[0042] In step (2):

[0043] In a preferred embodiment, the present invention does not specifically limit atmospheric pressure, but can be understood in the conventional sense, that is, atmospheric pressure is equal to the gas pressure generated by the atmosphere in which we live normally.

[0044] In a preferred embodiment, the mixture containing the precipitate is aged at 30-50°C. In this invention, to avoid solvent loss, reflux can be performed during the aging process.

[0045] In a preferred embodiment, the aging time is 10-25 hours, preferably 12-20 hours. In this invention, after aging, solid-liquid separation, washing, and drying are performed sequentially to obtain lanthanum hydroxide. Compared with commercially available nano-lanthanum hydroxide, this invention, by controlling the alkali concentration, using three-stage variable frequency ultrasound, and atmospheric pressure aging treatment, can prepare slender rod-shaped lanthanum hydroxide, which helps to increase the specific surface area of ​​the methane oxidative coupling catalyst and improve its catalytic activity.

[0046] In step (3):

[0047] In a preferred embodiment, the present invention does not specifically limit the soluble compounds containing Cs, Ce, Fe, B, Zn, Cd, and Ni elements. The modified auxiliary agent precursor is further preferably selected from one or more soluble compounds containing Cs, Ce, Fe, and Ni elements, and more preferably from soluble compounds containing Ce and / or Cs.

[0048] In a preferred embodiment, the concentration of the modified additive precursor in the solution containing the modified additive precursor is 0.5-10% by weight, preferably 1-5% by weight.

[0049] In a preferred embodiment, the molar ratio of lanthanum hydroxide to the solution containing the modified additive precursor is 1-100:1, preferably 10-60:1, based on the lanthanum element in lanthanum hydroxide and the modified element in the modified additive precursor.

[0050] In a preferred embodiment, the impregnation conditions include: an impregnation temperature of 20-80°C, preferably 35-50°C; and an impregnation time of 10-30 hours, preferably 18-24 hours.

[0051] In a preferred embodiment, after impregnation, the mixture containing lanthanum hydroxide and a modified precursor is directly dried to obtain the impregnated product.

[0052] In this invention, material loss during the impregnation process can be ignored; that is, the amount of material fed during the impregnation process is the elemental content in the prepared catalyst.

[0053] In step (4):

[0054] In a preferred embodiment, the impregnation product is calcined at 440-550°C to obtain the methane oxidative coupling catalyst.

[0055] In a preferred embodiment, the roasting time is 1-8 hours, more preferably 2-4 hours.

[0056] In a preferred embodiment, the burning is carried out in a carbon dioxide and / or air atmosphere.

[0057] The method for preparing the methane oxidative coupling catalyst provided in this invention eliminates the need for hydrothermal reaction under high pressure, allowing for the production of a highly catalytically active methane oxidative coupling catalyst under normal pressure. This reduces the preparation conditions for the methane oxidative coupling catalyst and makes it suitable for industrial application.

[0058] A third aspect of the present invention provides a method for preparing ethane and ethylene from methane, the method comprising: in the presence of an oxygen-containing gas, contacting methane with the methane oxidative coupling catalyst described in the first aspect of the present invention or the catalyst prepared by the preparation method described in the second aspect of the present invention to carry out a methane oxidative coupling reaction, thereby obtaining ethane and ethylene.

[0059] In a preferred embodiment, the conditions for the methane oxidative coupling reaction include: under normal pressure, the reaction temperature is 450-650℃, preferably 450-550℃; the molar ratio of methane to oxygen is 1-15:1, preferably 2-8:1; and the methane space velocity is 20000-200000 mL / g·h, preferably 40000-150000 mL / g·h.

[0060] Generally, the methane conversion activity and ethylene-ethane selectivity of methane oxidative coupling catalysts increase with increasing reaction temperature. The methane oxidative coupling catalyst provided in this invention can achieve very high methane conversion activity and ethylene-ethane selectivity at a low temperature of 450°C. Therefore, while considering both reaction temperature and catalyst activity, the preferred reaction temperature in this invention is 450-550°C.

[0061] The present invention will be described in detail below through embodiments.

[0062] The method for calculating methane conversion rate is as follows:

[0063] Methane conversion rate = Amount of methane consumed in the reaction / Initial amount of methane × 100%.

[0064] The method for calculating ethylene selectivity is as follows:

[0065] Ethylene selectivity = Amount of methane consumed to produce ethylene / Total methane consumption × 100%.

[0066] The method for calculating ethane selectivity is as follows:

[0067] Ethane selectivity = Amount of methane consumed to produce ethane / Total methane consumption × 100%.

[0068] The method for calculating the yield of C2 hydrocarbons is as follows:

[0069] C2 hydrocarbon yield = methane conversion rate × (ethane selectivity + ethylene selectivity).

[0070] Example 1

[0071] (1) Accurately weigh 5g of lanthanum nitrate hexahydrate, dissolve it in 155g of deionized water, and obtain a solution containing lanthanum nitrate (lanthanum element concentration is 1% by weight) after complete dissolution; add 12.5g of sodium hydroxide solution (sodium hydroxide concentration is 10% by weight) to the above solution containing lanthanum nitrate, and sonicate at 28kHz for 1h at room temperature, then sonicate at 45kHz for 2h; then sonicate at 100kHz for 2h to obtain a mixed solution containing precipitate;

[0072] (2) Under normal pressure, the above mixture was aged at 30°C for 20 hours, then cooled to room temperature and centrifuged. The solid obtained after centrifugation was first washed with deionized water until the pH of the washing solution was neutral, then washed once with ethanol, and then dried to obtain lanthanum hydroxide.

[0073] (3) Mix 2g of the above lanthanum hydroxide with 4.8g of cerium nitrate solution (cerium nitrate concentration is 1.6% by weight), impregnate at 40°C for 20h, and then dry to obtain the impregnated product;

[0074] (4) The above impregnation product was calcined in a carbon dioxide atmosphere at 500°C for 3 hours to obtain methane oxidative coupling catalyst A-1, whose composition and size parameters are shown in Table 1.

[0075] Example 2

[0076] (1) Accurately weigh 6g of lanthanum acetate monohydrate, dissolve it in 180g of deionized water, and obtain a solution containing lanthanum acetate (lanthanum element concentration is 1.34 wt%) after complete dissolution; add 15g of sodium hydroxide solution (sodium hydroxide concentration is 12 wt%) to the above solution containing lanthanum acetate, sonicate at 28kHz for 2h, then sonicate at 45kHz for 2h; then sonicate at 100kHz for 1h to obtain a mixed solution containing precipitate;

[0077] (2) Under normal pressure, the above mixture was aged at 45°C for 20 hours, then cooled to room temperature and centrifuged. The solid obtained after centrifugation was first washed with deionized water until the pH value of the washing solution was neutral, then washed once with ethanol, and then dried to obtain lanthanum hydroxide.

[0078] (3) Mix 1.93g of the above lanthanum hydroxide with 5g of cesium nitrate solution (the concentration of cesium nitrate is 3% by weight), impregnate at 35°C for 20h, and then dry to obtain the impregnated product;

[0079] (4) The above impregnated product was calcined in air atmosphere at 440°C for 2 hours to obtain methane oxidative coupling catalyst A-2, the composition and size parameters of which are shown in Table 1.

[0080] Example 3

[0081] (1) Accurately weigh 5g of lanthanum nitrate hexahydrate, dissolve it in 250g of deionized water, and obtain a solution containing lanthanum nitrate (lanthanum element concentration is 6% by weight) after complete dissolution; add 19.2g of sodium hydroxide solution (sodium hydroxide concentration is 8% by weight) to the above solution containing lanthanum nitrate, sonicate at 28kHz for 3h, then sonicate at 45kHz for 4h; then sonicate at 100kHz for 0.5h to obtain a mixed solution containing precipitate;

[0082] (2) Under normal pressure, the above mixture was aged at 70°C for 12 hours, then cooled to room temperature and centrifuged. The solid obtained after centrifugation was first washed with deionized water until the pH value of the washing solution was neutral, then washed once with ethanol, and then dried to obtain lanthanum hydroxide.

[0083] (3) Mix 1g of the above lanthanum hydroxide with 2.5g of nickel nitrate solution (the concentration of nickel nitrate is 3% by weight), impregnate at 50°C for 20h, and then dry to obtain the impregnated product;

[0084] (4) The above impregnated product was calcined in air atmosphere at 550°C for 2 hours to obtain methane oxidative coupling catalyst A-3, whose composition and size parameters are shown in Table 1.

[0085] Example 4

[0086] (1) Accurately weigh 12.3 g of lanthanum acetate monohydrate, dissolve it in 140 g of deionized water, and obtain a solution containing lanthanum acetate (lanthanum element concentration is 3.3 wt%) after complete dissolution; add 12.23 g of sodium hydroxide solution (sodium hydroxide concentration is 10 wt%) to the above solution containing lanthanum acetate, sonicate at 28 kHz for 5 h, then sonicate at 45 kHz for 4 h; then sonicate at 100 kHz for 1 h to obtain a mixed solution containing precipitate;

[0087] (2) Under normal pressure, the above mixture was aged at 65°C for 12 hours, then cooled to room temperature and centrifuged. The solid obtained after centrifugation was first washed with deionized water until the pH value of the washing solution was neutral, then washed once with ethanol, and then dried to obtain lanthanum hydroxide.

[0088] (3) Mix 1.2g of the above lanthanum hydroxide with 3g of ferric nitrate solution (ferric nitrate concentration is 5% by weight), impregnate at 50°C for 20h, and then dry to obtain the impregnated product;

[0089] (4) The above impregnated product was calcined in air atmosphere at 550°C for 2 hours to obtain methane oxidative coupling catalyst A-4, whose composition and size parameters are shown in Table 1.

[0090] Comparative Example 1

[0091] Similar to Example 1, except that the ultrasonic treatment in step (1) was omitted, and methane oxidative coupling catalyst D-1 was obtained, the composition and size parameters of which are shown in Table 1.

[0092] Comparative Example 2

[0093] Similar to Example 1, except that the ultrasonic treatment in step (1) was to sonicate at 28 kHz for 5 h to obtain methane oxidative coupling catalyst D-2, the composition and size parameters of which are shown in Table 1.

[0094] Comparative Example 3

[0095] Similar to Example 1, except that in step (4), the calcination temperature is 700°C, and methane oxidative coupling catalyst D-3 is obtained, the composition and size parameters of which are shown in Table 1.

[0096] Table 1

[0097]

[0098]

[0099] The component content in the methane oxidative coupling catalyst was calculated based on the feed amount. The length and diameter of lanthanum oxycarbonate were measured using a scanning electron microscope (SEM) scale. A total of seven samples were measured, and the average value was taken as the test result. The specific surface area was characterized using N2 physical adsorption-desorption characterization. The specific operation was as follows: the pore structure of the sample was characterized using an ASAP-2420 N2 physical adsorption-desorption instrument. 0.05g of sample was vacuum-treated at 300℃ for 3-4 hours. Finally, the product was placed under liquid nitrogen cryogenic (-200℃) conditions for nitrogen adsorption-desorption testing. The specific surface area was calculated using the BET equation.

[0100] in, Figure 1 This is a scanning electron microscope image of the lanthanum hydroxide prepared in Example 1 of this invention. Figure 2 This is a scanning electron microscope (SEM) image of the methane oxidative coupling catalyst A-1 prepared in Example 1 of this invention. Figure 1 and Figure 2 It is known that the preparation method of this invention can yield well-formed, elongated rod-shaped lanthanum hydroxide and rod-shaped methane oxidative coupling catalyst.

[0101] Test Example 1

[0102] The catalysts prepared in Examples 1-4 and Comparative Examples 1-3 were compressed into sheets and crushed through a 40-60 mesh sieve. 0.1 g of each sheet was placed into a fixed-bed quartz tube reactor and subjected to methane oxidative coupling reaction under normal pressure. The reaction conditions and results are shown in Table 2.

[0103] Table 2

[0104]

[0105]

[0106] As shown in Table 2, the methane oxidative coupling catalyst prepared in this invention exhibits high catalytic activity at a low temperature of 450℃, making it suitable for industrial application.

[0107] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A methane oxidation coupling catalyst characterized by, The catalyst comprises lanthanum oxide carbonate and a modified auxiliary agent supported on the lanthanum oxide carbonate; wherein the lanthanum oxide carbonate exists in the form of rod-shaped particles, the length of the rod-shaped particles is 200-500 nm, the diameter is 5-50 nm, and the specific surface area is 50-100 m² / g; the modified auxiliary agent is a modified element oxide, and the modified element is selected from one or more of Cs, Ce, Fe, and Ni; in the catalyst, the molar ratio of lanthanum element to modified element is 1-100:1; The preparation method of the methane oxidative coupling catalyst comprises the following steps: (1) adding an alkali solution into a solution containing a soluble lanthanum salt, and performing a reaction under ultrasonic conditions to obtain a mixed solution containing precipitates; wherein the ultrasonic operation is performed at room temperature, and the ultrasonic operation conditions include first ultrasonic operation at 20-30 kHz for 1-5 h, then ultrasonic operation at 40-60 kHz for 1-5 h, and finally ultrasonic operation at 80-120 kHz for 0.5-2 h; (2) aging the mixed solution containing the precipitates at 25-75 °C under normal pressure to obtain lanthanum hydroxide; (3) mixing the lanthanum hydroxide with a solution containing a modified auxiliary agent precursor, and then performing impregnation to obtain an impregnated product; wherein the modified auxiliary agent precursor is selected from one or more of soluble compounds containing Cs, Ce, Fe, and Ni elements; (4) calcining the impregnated product at 400-600 °C to obtain the methane oxidative coupling catalyst.

2. The catalyst of claim 1, wherein, The length of the rod-shaped particles is 200-350 nm, the diameter is 10-30 nm, and the specific surface area is 55-85 m² / g.

3. The catalyst of claim 1, wherein, The molar ratio of lanthanum element to modified element is 10-60:

1.

4. A process for the preparation of a methane oxidation coupling catalyst as claimed in any one of claims 1 to 3, characterized in that The method comprises the following steps: (1) adding an alkali solution into a solution containing a soluble lanthanum salt, and performing a reaction under ultrasonic conditions to obtain a mixed solution containing precipitates; wherein the ultrasonic operation is performed at room temperature, and the ultrasonic operation conditions include first ultrasonic operation at 20-30 kHz for 1-5 h, then ultrasonic operation at 40-60 kHz for 1-5 h, and finally ultrasonic operation at 80-120 kHz for 0.5-2 h; (2) aging the mixed solution containing the precipitates at 25-75 °C under normal pressure to obtain lanthanum hydroxide; (3) mixing the lanthanum hydroxide with a solution containing a modified auxiliary agent precursor, and then performing impregnation to obtain an impregnated product; wherein the modified auxiliary agent precursor is selected from one or more of soluble compounds containing Cs, Ce, Fe, and Ni elements; the molar ratio of the lanthanum hydroxide to the solution containing the modified auxiliary agent precursor is 1-100:1, calculated based on the lanthanum element in the lanthanum hydroxide and the modified element in the modified auxiliary agent precursor; (4) calcining the impregnated product at 400-600 °C to obtain the methane oxidative coupling catalyst.

5. The production method according to claim 4, wherein In step (1), the alkali solution is an aqueous alkali solution, and the alkali in the alkali solution is selected from sodium hydroxide and / or potassium hydroxide.

6. The production method according to claim 4, wherein The alkali in the alkali solution is sodium hydroxide.

7. The production method according to claim 4, wherein The concentration of the alkali in the alkali solution is 5-12 wt%.

8. The production method according to claim 4, wherein The concentration of the alkali in the alkali solution is 10-12 wt%.

9. The production method according to claim 4, wherein, The concentration of lanthanum in the solution containing the soluble lanthanum salt is 0.05-10% by weight.

10. The production method according to claim 4, wherein, The concentration of lanthanum in the solution containing the soluble lanthanum salt is 0.1-5% by weight.

11. The production method according to claim 4, wherein The mass ratio of the lye to the solution containing the soluble lanthanum salt is 1:5-20.

12. The production method according to claim 4, wherein, The mass ratio of the lye to the solution containing the soluble lanthanum salt is 1:10-15.

13. The production method according to claim 4, wherein, The ultrasonic operation is carried out at room temperature, and the operation conditions of the ultrasonic operation include first ultrasonic operation at 26-28 kHz for 2-3 h, then ultrasonic operation at 45-50 kHz for 2-3 h, and further ultrasonic operation at 90-110 kHz for 1.5-2 h.

14. The production method according to claim 4, wherein, In step (2), the mixed solution is aged at 30-50℃.

15. The production method according to claim 4, wherein, The aging time is 10-25 h.

16. The method of making according to claim 4, wherein, The aging time is 12-20 h.

17. The method of making according to claim 4, wherein, In step (3), the molar ratio of lanthanum hydroxide to the solution containing the modification aid precursor is 10-60:1, wherein the lanthanum is in the lanthanum hydroxide, and the modification element is in the modification aid precursor.

18. The method of making according to claim 4, wherein, The operation conditions of the impregnation include: the impregnation temperature is 20-80℃; and the impregnation time is 10-30 h.

19. The method of making according to claim 4, wherein, The impregnation temperature is 35-50℃.

20. The method of manufacturing according to claim 4, wherein, The impregnation time is 18-24 h.

21. The method of manufacturing according to claim 4, wherein, In step (4), the impregnation product is calcined at 440-550℃ to obtain the methane oxidative coupling catalyst.

22. The method of manufacturing according to claim 4, wherein, The calcination time of the calcination is 1-8 h.

23. The method of manufacturing according to claim 4, wherein, The calcination time of the calcination is 2-4 h.

24. A process for the production of ethane and ethylene from methane, characterized in that, The method comprises: contacting methane with the methane oxidative coupling catalyst in the presence of an oxygen-containing gas to carry out a methane oxidative coupling reaction, so as to obtain ethane and ethylene, wherein the methane oxidative coupling catalyst is prepared by the preparation method in any one of claims 1-3 or any one of claims 4-23.

25. The method of claim 24, wherein, The conditions of the methane oxidative coupling reaction include: the reaction temperature is 450-650℃; the molar ratio of methane to oxygen is 1-15:1; and the methane space velocity is 20000-200000 mL / g·h.

26. The method of claim 24, wherein, The reaction temperature is 450-550℃.

27. The method of claim 24, wherein, The molar ratio of methane to oxygen is 2-8:

1.

28. The method of claim 24, wherein, The methane space velocity is 40000-150000 mL / g·h.

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