Method and reactor for preparing C2 hydrocarbon and application of method and reactor

Abstract

The invention relates to the technical field of oxidative coupling of methane, and discloses a method and a reactor for preparing C2 hydrocarbon and application of the method and the reactor. The method provided by the invention comprises the following steps: introducing CH4, O2 and a manganese salt solution into a reactor, and carrying out methane oxidative coupling reaction. The method effectively improves the selectivity and yield of C2 hydrocarbon in the oxidative coupling reaction of methane, has the advantages of simplicity, easiness in implementation, easily available raw materials and the like, and has industrial application potential. Moreover, the method provided by the invention has the effect of improving the selectivity and the yield of the carbon dihydrocarbon to different extents for reactions catalyzed by various different methane oxidative coupling catalysts, so that the method has the advantages of universality and wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of methane oxidative coupling, and in particular to a method for preparing carbon dihydrocarbons, a reactor and applications thereof. Background Art

[0002] C2H2O, especially ethylene, is a very important basic raw material for the chemical industry. The main method for producing C2H2O is currently oil cracking. However, oil resources are becoming scarce year by year, and the oil cracking process has serious environmental pollution and other problems. In recent years, seeking new C2H2O production routes has become a research focus in the chemical industry. Natural gas occupies a very important position among the three major energy sources in modern industry, and has the advantages of abundant reserves and green and clean. The main component of natural gas is methane, so the development of a method for preparing C2H2O by oxidative coupling of methane is of great significance for the efficient and clean use of natural gas.

[0003] The methane oxidative coupling technology route was first proposed in 1982. However, due to the great difficulty in the activation and directional conversion of methane, no industrial application equipment has been developed so far. In the current research on the methane oxidative coupling reaction, researchers have found that due to the high activation energy of methane, the temperature of the methane oxidative coupling reaction is high. However, as the reaction time increases, the activity of the catalyst gradually decreases, which further reduces the yield of carbon dihydrocarbons. Therefore, it is urgent to develop methods and supporting production equipment that can improve the yield of carbon dihydrocarbons in the methane oxidative coupling reaction. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems in the prior art that the yield of carbon dihydrocarbons is not ideal and it is difficult to achieve industrial application when preparing carbon dihydrocarbons by oxidative coupling of methane, and to provide a method for preparing carbon dihydrocarbons, a reactor and their applications. The method provided by the present invention effectively improves the yield of carbon dihydrocarbons in the oxidative coupling reaction of methane by introducing a manganese salt solution and co-feeding the reaction gas, laying a foundation for the industrial application of preparing carbon dihydrocarbons by oxidative coupling of methane.

[0005] In order to achieve the above object, the present invention provides a method for preparing carbon dihydrocarbons by oxidative coupling of methane, the method comprising: 4 , O 2 And the manganese salt solution is introduced into the reactor to carry out the methane oxidative coupling reaction.

[0006] The second aspect of the present invention provides a methane oxidative coupling reactor, which includes a reactor cavity and an introduction pipe, wherein the introduction pipe is used to introduce a manganese salt solution into the reactor cavity, and the outlet of the introduction pipe is arranged above the catalyst bed in the reactor cavity.

[0007] The third aspect of the present invention provides the use of the method described in the first aspect and / or the reactor described in the second aspect in improving the yield of carbon dihydrocarbons in the oxidative coupling reaction of methane.

[0008] Through the above technical solution, the present invention can at least achieve the following beneficial effects:

[0009] (1) The method provided by the present invention can effectively improve the selectivity and yield of carbon dihydrocarbons in the methane oxidative coupling reaction, and can operate stably for a long time, laying a foundation for the industrial application of the methane oxidative coupling reaction.

[0010] (2) The method provided by the present invention is simple and easy to implement, the raw materials are easily available, and it is universal in the methane oxidative coupling reaction. It can be applied to reactions catalyzed by various methane oxidative coupling catalysts and has a significant improvement in the selectivity and yield of dihydrocarbons.

[0011] (3) The device provided by the present invention has a simple structure and can be obtained by simply modifying an existing reactor. It has the advantages of low cost and easy availability. DETAILED DESCRIPTION

[0012] 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.

[0013] In the present invention, "C2 hydrocarbons" and "C2 hydrocarbons" have the same meaning and can be used interchangeably. They refer to ethane and / or ethylene.

[0014] The inventors of the present invention cleverly discovered in their research that by adding a manganese salt solution (for example, co-feeding with a reaction gas containing methane and oxygen) during the methane oxidative coupling reaction, the selectivity and yield of carbon dihydrocarbons can be effectively improved.

[0015] Based on this, the first aspect of the present invention provides a method for preparing carbon dihydrocarbons, the method comprising: 4 , O 2 And the manganese salt solution is introduced into the reactor to carry out the methane oxidative coupling reaction.

[0016] According to a preferred embodiment of the present invention, the manganese salt solution is introduced into the reactor by an introduction tube, and the distance between the outlet of the introduction tube and the catalyst bed is 1-5 times, preferably 1-3 times, the height of the catalyst bed. "The distance between the outlet of the introduction tube and the catalyst bed" refers to the distance between the outlet of the introduction tube and the top plane after the catalyst is loaded in the reactor cavity, and "the height of the catalyst bed" refers to the loading height of the catalyst in the reactor cavity. For example, relative to a catalyst bed with a loading height of 16 mm, the distance between the outlet of the introduction tube and the catalyst bed can be 16-80 mm, that is, the distance between the plane where the outlet of the introduction tube is located and the upper surface of the bed after the catalyst is loaded can be 16-80 mm.

[0017] In the present invention, there is no particular limitation on the specific amount of the manganese salt solution, the concentration of the manganese salt solution, the type of the manganese salt solution, etc., as long as the selectivity and yield of carbon dihydrocarbons in the methane oxidative coupling reaction can be improved to a relatively ideal level.

[0018] According to some preferred embodiments of the present invention, the amount of the manganese salt solution is such that the manganese salt introduced per unit time and CH 4 The weight ratio of the present invention is 1-230:1, preferably 1-150:1. For example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 5:1, 8:1, 10:1, 12:1, 15:1, 18:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 110:1, 120:1, 130:1, 140:1, 150:1, 180:1, 200:1, 230:1, or any intermediate ratio within the range formed by any two of the above ratios.

[0019] According to a preferred embodiment of the present invention, wherein the CH 4 The volume ratio of the manganese salt solution is 0.5-4:1, preferably 0.5-2:1.

[0020] According to a preferred embodiment of the present invention, the concentration of the manganese salt solution is 0.5-8% by weight, preferably 0.5-3% by weight.

[0021] In the method provided by the present invention, a solution prepared by a water-soluble manganese salt is preferably used. According to some preferred embodiments of the present invention, the manganese salt is selected from manganese nitrate and / or manganese acetate.

[0022] When the method provided by the present invention is used for methane oxidative coupling reactions catalyzed by various catalysts, the selectivity and yield of dihydrocarbons can be improved. Therefore, the conditions for methane oxidative coupling reactions to which the present invention can be applied are relatively broad and can be specifically determined according to the type of catalyst used and its applicable reaction conditions.

[0023] According to some preferred embodiments of the present invention, the conditions for the methane oxidative coupling reaction include: CH 4 and O 2 The volume ratio of is 2-10:1, preferably 2-5:1; the reaction temperature is 700-900℃, preferably 750-850℃; the hourly space velocity of the reaction gas is 5000-15000mL / (g·h), and the reaction gas is methane and oxygen. The unit "mL / (g·h)" means the reaction gas (CH 4 +O 2 ) in total (mL).

[0024] In the method provided by the present invention, there is no particular limitation on the reaction pressure, and no special adjustment is required, and the pressure of the raw materials can usually be used. Preferably, the pressure (gauge pressure) of the methane oxidative coupling reaction can be 0.001-0.02 MPa.

[0025] The second aspect of the present invention provides a methane oxidative coupling reactor, which includes a reactor cavity and an introduction pipe, wherein the introduction pipe is used to introduce a manganese salt solution into the reactor cavity, and the outlet of the introduction pipe is arranged above the catalyst bed in the reactor cavity.

[0026] According to a preferred embodiment of the present invention, the distance between the outlet of the introduction pipe and the catalyst bed is 1-5 times, preferably 1-3 times, the height of the catalyst bed.

[0027] According to a preferred embodiment of the present invention, the introduction pipe is located at the center of the reactor cavity, that is, the introduction pipe is inserted into the reactor cavity along the central axis of the reactor cavity.

[0028] According to a preferred embodiment of the present invention, the ratio of the inner diameter of the reactor cavity to the inner diameter of the introduction pipe is 4-10:1.

[0029] According to a preferred embodiment of the present invention, the reactor cavity is filled with a catalyst.

[0030] Preferably, fillers are loaded at both ends of the catalyst in the reactor cavity, preferably inert materials are used as fillers. "Inert materials" refer to substances that are not reactive in the methane oxidative coupling reaction, such as alumina, silicon dioxide (such as quartz sand), etc.

[0031] The present invention has no particular restrictions on the specific material and size of the reactor, and any reactor in the art that can be used for methane oxidative coupling reaction and has the above characteristics belongs to the content protected by the present invention. For example, the reactor provided by the present invention can be made of quartz, alumina, stainless steel, etc.

[0032] The third aspect of the present invention provides the use of the method described in the first aspect and / or the reactor described in the second aspect in improving the yield of carbon dihydrocarbons in the oxidative coupling reaction of methane.

[0033] The present invention will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0034] In the following examples, unless otherwise specified, all reagents used were commercial products purchased from regular chemical suppliers and were of analytical grade.

[0035] In the following embodiments, unless otherwise specified, the reactor used includes a quartz reaction chamber and a manganese salt solution introduction tube inserted along the center of the reaction chamber, with an outer diameter of 3 mm and a thickness of 0.9 mm. The inner diameter of the quartz reaction chamber is 10 mm, the length is 530 mm, the thickness of the reaction chamber is 1.5 mm, and the catalyst loading in the reaction chamber is 0.4 g.

[0036] The catalysts used in the following examples were prepared as follows:

[0037] According to the selection and content of the active components in Table 1, the precursor of the active component (the precursor of W is ammonium tungstate, and the precursors of the other active components are all nitrates thereof) is weighed and added to 25g of deionized water (50°C), and the carrier is added, stirred for 2 hours, dried at 120°C for 24 hours, and solid A is obtained, and then calcined at 750°C for 6 hours to obtain a catalyst. The elemental composition of the catalyst is determined by X-ray fluorescence method, and the specific detection is carried out in accordance with GB / T 30905-2014.

[0038] Table 1

[0039]

[0040] Note: The content of each active component in the catalyst is the relative content calculated based on 100g of carrier.

[0041] Example 1

[0042] The catalyst bed is filled with 1# catalyst, and the bed height is 17 mm. The outlet of the introduction pipe is located above the catalyst bed, 20 mm away from the upper surface of the catalyst filled in the catalyst bed. During the reaction, a manganese nitrate solution with a concentration of 2% by weight is fed synchronously with methane and oxygen through the introduction pipe. The reaction pressure is the pressure generated by the raw material itself, that is, 0.015 MPa, the reaction temperature is 810°C, the volume ratio of methane to oxygen is 2.2:1, the volume ratio of methane fed to manganese nitrate solution is 0.5:1, and the reaction gas hourly space velocity based on methane and oxygen is 10000 mL / (g·h).

[0043] Comparative Example 1

[0044] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that no manganese nitrate solution was introduced into the introduction tube.

[0045] Example 2

[0046] The catalyst bed is filled with 2# catalyst, and the bed height is 16mm. The outlet of the introduction pipe is located above the catalyst bed, 30mm away from the upper surface of the catalyst filled in the catalyst bed. During the reaction, a manganese acetate solution with a concentration of 0.5% by weight is fed synchronously with methane and oxygen through the introduction pipe. The reaction pressure is the pressure generated by the raw material itself, that is, 0.015MPa, the reaction temperature is 750°C, the volume ratio of methane to oxygen is 3:1, the volume ratio of methane fed to manganese acetate solution is 4:1, and the reaction gas hourly space velocity based on methane and oxygen is 15000mL / (g·h).

[0047] Comparative Example 2

[0048] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 2, except that the manganese acetate solution was not introduced into the introduction tube.

[0049] Example 3

[0050] The catalyst bed is filled with 3# catalyst, and the bed height is 15mm. The outlet of the introduction pipe is located above the catalyst bed, 40mm away from the upper surface of the catalyst filled in the catalyst bed. During the reaction, a manganese nitrate solution with a concentration of 3% by weight is fed synchronously with methane and oxygen through the introduction pipe. The reaction pressure is the pressure generated by the raw material itself, that is, 0.015MPa, the reaction temperature is 850°C, the volume ratio of methane to oxygen is 5:1, the volume ratio of methane fed to manganese nitrate solution is 2:1, and the reaction gas hourly space velocity based on methane and oxygen is 12000mL / (g·h).

[0051] Comparative Example 3

[0052] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 3, except that no manganese nitrate solution was introduced into the introduction tube.

[0053] Example 4

[0054] The catalyst bed is filled with 4# catalyst, and the bed height is 16mm. The outlet of the introduction pipe is located above the catalyst bed, 35mm away from the upper surface of the catalyst filled in the catalyst bed. During the reaction, a manganese nitrate solution with a concentration of 5% by weight is fed synchronously with methane and oxygen through the introduction pipe. The reaction pressure is the pressure generated by the raw material itself, that is, 0.015MPa, the reaction temperature is 830°C, the volume ratio of methane to oxygen is 4:1, the volume ratio of methane fed to manganese nitrate solution is 1.5:1, and the reaction gas hourly space velocity based on methane and oxygen is 8000mL / (g·h).

[0055] Comparative Example 4

[0056] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 4, except that no manganese nitrate solution was introduced into the introduction tube.

[0057] Example 5

[0058] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that the volume ratio of methane to manganese nitrate solution was 10:1.

[0059] Example 6

[0060] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that the concentration of the manganese nitrate solution was 20% by weight.

[0061] Example 7

[0062] Comparative Example 7 The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that the feed pipe of the sodium tungstate solution was inserted into the catalyst bed at a depth of 1 cm.

[0063] Example 8

[0064] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that the concentration of the manganese salt solution was adjusted according to Table 2.

[0065] Table 2

[0066] serial number Manganese nitrate solution concentration (weight %) <![CDATA[The weight ratio of manganese nitrate to CH 4 > 8-1 0.5 14.1:1 8-2 3 84.5:1 8-3 5 140.8:1 8-4 8 225.4:1 8-5 8.5 239.4:1 8-6 0.3 8.5:1

[0067] Example 9

[0068] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that the volume ratio of the manganese salt solution to methane was adjusted according to Table 3.

[0069] Table 3

[0070] serial number <![CDATA[CH 4 Volume ratio of manganese nitrate solution]]> <![CDATA[Manganese nitrate and CH 4 weight ratio]]> 9-1 0.2:1 140.8:1 9-2 1:1 28.2:1 9-3 2:1 14.1:1 9-4 3:1 9.4:1 9-5 4.5:1 6.3:1

[0071] Example 10

[0072] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that the distance between the outlet of the introduction pipe and the catalyst bed was adjusted according to Table 4.

[0073] Table 4

[0074] serial number Distance between inlet pipe outlet and catalyst bed (mm) 10-1 5 10-2 50 10-3 85 10-4 100

[0075] Comparative Example 5

[0076] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that the manganese nitrate solution was replaced by an equal amount of water.

[0077] Comparative Example 6

[0078] The oxidative coupling reaction of methane to produce dihydrocarbons was carried out according to the method of Example 1, except that no manganese nitrate solution was introduced into the feed pipe, but 4 g of manganese nitrate particles were doped into the catalyst.

[0079] Test Example 1

[0080] The components of the reaction products obtained after 2h and 200h of stable reaction in the above examples and comparative examples were detected using a gas chromatograph model 7890A produced by Agilent. The reaction products were measured using a dual detection channel three-valve four-column system, in which the FID detector was connected to an alumina column to analyze CH 4 , C 2 H 6 , C 2 H 4 , C 3 H 8 , C 3 H 6 , C 4 H 10 , C 4 H 8 , C n H m The TCD detector is mainly used to detect CO, CO 2 、N 2 , O 2 , CH 4 Then the following formula is used to calculate the conversion rate of methane and CO x (CO+CO 2 ) selectivity, selectivity and yield of carbon dihydrocarbons. The results are shown in Table 5.

[0081] Methane conversion rate = amount of methane consumed by the reaction / initial amount of methane × 100%

[0082] Ethylene selectivity = amount of methane consumed by the generated ethylene / total methane consumption × 100%

[0083] Ethane selectivity = amount of methane consumed to produce ethane / total methane consumption × 100%

[0084] C2 selectivity = ethane selectivity + ethylene selectivity

[0085] CO x Selectivity = CO and CO produced 2 Total amount of methane consumed / total methane consumption × 100%

[0086] C2 hydrocarbon yield = methane conversion × (ethane selectivity + ethylene selectivity)

[0087] Table 5

[0088]

[0089] * In Table 5, methane conversion, C2 hydrocarbon selectivity and CO x Selectivity refers to the corresponding data after the reaction stabilizes for 2 h.

[0090] 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 method for preparing carbon dihydrocarbons, characterized in that: The method comprises: introducing CH4, O2 and a manganese salt solution into a reactor to carry out a methane oxidative coupling reaction.

2. The method according to claim 1, wherein: The manganese salt solution is introduced into the reactor through an introduction pipe, and the distance between the outlet of the introduction pipe and the catalyst bed is 1-5 times, preferably 1-3 times, the height of the catalyst bed.

3. The method according to claim 1 or 2, wherein: The amount of the manganese salt solution is such that the weight ratio of the manganese salt to CH4 introduced per unit time is 1-230:1, preferably 1-150:

1.

4. The method according to any one of claims 1 to 3, wherein: The volume ratio of CH4 to manganese salt solution is 0.5-4:1, preferably 0.5-2:1; And / or, the concentration of the manganese salt solution is 0.5-8 wt %, preferably 0.5-3 wt %.

5. The method according to any one of claims 1 to 4, wherein: The manganese salt is selected from manganese nitrate and / or manganese acetate.

6. The method according to claim 1, wherein: The conditions for the methane oxidative coupling reaction include: a volume ratio of CH4 to O2 of 2-10:1, preferably 2-5:1; a reaction temperature of 700-900°C, preferably 750-850°C; an hourly space velocity of the reaction gas of 5000-15000 mL / (g·h), the reaction gas being calculated as methane and oxygen.

7. A methane oxidative coupling reactor, characterized in that: The reactor comprises a reactor cavity and an introduction pipe, wherein the introduction pipe is used to introduce a manganese salt solution into the reactor cavity, and an outlet of the introduction pipe is arranged above a catalyst bed in the reactor cavity.

8. The reactor according to claim 7, wherein The distance between the outlet of the introduction pipe and the catalyst bed is 1-5 times the height of the catalyst bed; And / or, the introduction pipe is located in the center of the reactor cavity; And / or, the ratio of the inner diameter of the reactor cavity to the inner diameter of the introduction pipe is 4-10:

1.

9. The reactor according to claim 7, wherein The reactor cavity is filled with a catalyst; Preferably, in the reactor cavity, fillers are loaded at both ends of the catalyst, and preferably inert materials are used as the fillers.

10. Use of the method according to any one of claims 1 to 6, and / or the reactor according to any one of claims 7 to 9 in improving the yield of dihydrocarbons in the oxidative coupling reaction of methane.

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