Process for the preparation of carbon dihydrocarbons, reactor and their use

Abstract

The present application relates to the technical field of methane oxidation coupling, and discloses a method for preparing carbon dihydrocarbon, a reactor and application thereof.The method provided by the present application comprises the following steps: introducing CH4, O2 and a manganese salt solution into a reactor to perform a methane oxidation coupling reaction.The method effectively improves the selectivity and yield of carbon dihydrocarbon in the methane oxidation coupling reaction, has the advantages of simplicity, easy operation and easy availability of raw materials, and has the potential for industrial application.Furthermore, the method provided by the present application has the effect of improving the selectivity and yield of carbon dihydrocarbon to different degrees for reactions catalyzed by various methane oxidation coupling catalysts, which indicates that the method has universality and wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of methane oxidative coupling technology, and more specifically, to a method for preparing C2 hydrocarbons, a reactor, and their applications. Background Technology

[0002] C2 hydrocarbons, especially ethylene, are crucial basic raw materials for the chemical industry. Currently, the main method for producing C2 hydrocarbons is petroleum cracking. However, petroleum resources are becoming increasingly scarce, and petroleum cracking processes cause serious environmental pollution. In recent years, seeking new C2 hydrocarbon production routes has become a key research focus in the chemical industry. Natural gas plays a vital role among the three major energy sources in modern industry, possessing advantages such as abundant reserves and being environmentally friendly. The main component of natural gas is methane; therefore, developing methods for producing C2 hydrocarbons via methane oxidative coupling is of great significance for the efficient and clean utilization of natural gas.

[0003] The methane oxidative coupling technology route was first proposed in 1982. However, due to the extreme difficulty in activating and directionally converting methane, no industrial-scale application equipment has yet been developed. Current research on the methane oxidative coupling reaction has revealed that the high activation energy of methane leads to high reaction temperatures. However, as the reaction time increases, the catalyst activity gradually decreases, further reducing the yield of C2 hydrocarbons. Therefore, there is an urgent need to develop methods and supporting production equipment to improve the yield of C2 hydrocarbons in the methane oxidative coupling reaction. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of unsatisfactory C2 hydrocarbon yields and difficulties in industrial application during the oxidative coupling of methane in existing technologies. This invention provides a method, reactor, and their applications for preparing C2 hydrocarbons. The method provided by this invention effectively improves the yield of C2 hydrocarbons in the oxidative coupling of methane by introducing a manganese salt solution as a co-feed with the reactant gas, laying the foundation for the industrial application of C2 hydrocarbon preparation via oxidative coupling of methane.

[0005] To achieve the above objectives, the present invention provides a method for preparing C2 hydrocarbons by oxidative coupling of methane, the method comprising: introducing CH4, O2 and a manganese salt solution into a reactor to carry out a methane oxidative coupling reaction.

[0006] A second aspect of the present invention provides a methane oxidative coupling reactor, the reactor comprising a reactor chamber and an inlet pipe, the inlet pipe being used to introduce a manganese salt solution into the reactor chamber, and its outlet being located above the catalyst bed in the reactor chamber.

[0007] The third aspect of the present invention provides the application of the method described in the first aspect, and / or the reactor described in the second aspect, in improving the yield of C2 hydrocarbons in the oxidative coupling reaction of methane.

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

[0009] (1) The method provided by the present invention can effectively improve the selectivity and yield of C2 hydrocarbons in the methane oxidative coupling reaction, and can operate stably for a long time, laying the 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 readily available, and it is universally applicable to the methane oxidative coupling reaction. It can be applied to the reaction catalyzed by various methane oxidative coupling catalysts, and it can significantly improve the selectivity and yield of C2 hydrocarbons.

[0011] (3) The device provided by the present invention has a simple structure and can be obtained by simple modification of the existing reactor. It has the advantages of low cost and easy availability. Detailed Implementation

[0012] 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.

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

[0014] The inventors of this invention have ingeniously discovered in their research that by adding a manganese salt solution (e.g., co-feeding with a reaction gas containing methane and oxygen) during the methane oxidative coupling reaction, the selectivity and yield of C2 hydrocarbons can be effectively improved.

[0015] Based on this, the first aspect of the present invention provides a method for preparing C2 hydrocarbons, the method comprising: introducing CH4, O2 and a manganese salt solution into a reactor to carry out a methane oxidative coupling reaction.

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

[0017] In this invention, there are no particular restrictions on the specific amount, concentration, or type of manganese salt solution used, as long as the selectivity and yield of C2 hydrocarbons in the methane oxidative coupling reaction are improved to a more ideal level.

[0018] According to some preferred embodiments of the present invention, the amount of manganese salt solution used is such that the weight ratio of manganese salt to CH4 introduced per unit time 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, the volume ratio of CH4 to 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 this invention, a solution prepared with a water-soluble manganese salt is preferably used. According to some preferred embodiments of the invention, the manganese salt is selected from manganese nitrate and / or manganese acetate.

[0022] The method provided by this invention can improve the selectivity and yield of C2 hydrocarbons in methane oxidative coupling reactions catalyzed by various catalysts. Therefore, the conditions applicable to methane oxidative coupling reactions of this invention are relatively broad, and can be determined according to the type of catalyst used and the applicable reaction conditions.

[0023] According to some preferred embodiments of the present invention, 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℃, preferably 750-850℃; and a space velocity of 5000-15000 mL / (g·h) for the reaction gas, wherein the reaction gas is methane and oxygen. The unit "mL / (g·h)" means the total amount (mL) of reaction gas (CH4+O2) passing through in 1 hour relative to 1 g of catalyst.

[0024] In the method provided by this invention, there are no particular limitations on the reaction pressure, nor is it necessary to adjust it specially; the pressure inherent to the raw materials is usually sufficient. Preferably, the pressure (gauge pressure) of the methane oxidative coupling reaction can be 0.001-0.02 MPa.

[0025] A second aspect of the present invention provides a methane oxidative coupling reactor, the reactor comprising a reactor chamber and an inlet pipe, the inlet pipe being used to introduce a manganese salt solution into the reactor chamber, and its outlet being located above the catalyst bed in the reactor chamber.

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

[0027] According to a preferred embodiment of the present invention, the inlet pipe is located at the center of the reactor cavity. That is, the inlet 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 inlet 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, the reactor cavity is filled with a packing agent at both ends of the catalyst, and preferably an inert material is used as the packing agent. "Inert material" refers to a substance that does not have reactivity in the methane oxidative coupling reaction, such as alumina, silica (e.g., quartz sand), etc.

[0031] This invention does not impose any particular limitations on the specific material and size of the reactor. Any reactor in the art that can be used for methane oxidative coupling reaction and has the aforementioned characteristics is within the scope of protection of this invention. For example, the reactor provided by this invention can be made of quartz, alumina, stainless steel, etc.

[0032] The third aspect of the present invention provides the application of the method described in the first aspect, and / or the reactor described in the second aspect, in improving the yield of C2 hydrocarbons in the oxidative coupling reaction of methane.

[0033] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments 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] Unless otherwise specified, all reagents used in the following examples are commercially available products purchased from legitimate chemical suppliers and are of analytical purity.

[0035] In the following embodiments, unless otherwise specified, the reactor used includes a quartz reaction chamber and a manganese salt solution inlet pipe 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 according to the following method:

[0037] According to the selection and content of active components in Table 1, the precursors of the active components (the precursor of W is ammonium tungstate, and the precursors of the other active components are their nitrates) were weighed and added to 25g of deionized water (50℃). The support was added, and the mixture was stirred for 2 hours. After drying at 120℃ for 24 hours, solid A was obtained, and then calcined at 750℃ for 6 hours to obtain the catalyst. The elemental composition of the catalyst was determined by X-ray fluorescence spectrometry, and the specific detection was 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 a relative content calculated based on 100g of support.

[0041] Example 1

[0042] The catalyst bed is filled with catalyst #1, with a bed height of 17 mm. The outlet of the inlet pipe is located above the catalyst bed, 20 mm from the top surface of the catalyst. During the reaction, a 2% (w / w) manganese nitrate solution is fed simultaneously with methane and oxygen through the inlet pipe. The reaction pressure is the pressure generated by the feed itself, i.e., 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 to manganese nitrate solution in the feed is 0.5:1; and the gas hourly space velocity (GHSV) for the reaction (based on methane and oxygen) is 10000 mL / (g·h).

[0043] Comparative Example 1

[0044] The reaction for the oxidative coupling of methane to produce C2 hydrocarbons was carried out according to the method of Example 1, except that manganese nitrate solution was not introduced into the inlet tube.

[0045] Example 2

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

[0047] Comparative Example 2

[0048] The reaction for the oxidative coupling of methane to produce C2 hydrocarbons was carried out according to the method of Example 2, except that manganese acetate solution was not introduced into the inlet tube.

[0049] Example 3

[0050] The catalyst bed is filled with catalyst #3, with a bed height of 15 mm. The outlet of the inlet pipe is located above the catalyst bed, 40 mm from the top surface of the catalyst. During the reaction, a 3% (w / w) manganese nitrate solution is fed simultaneously with methane and oxygen through the inlet pipe. The reaction pressure is the pressure generated by the feed itself, i.e., 0.015 MPa; the reaction temperature is 850 °C; the volume ratio of methane to oxygen is 5:1; the volume ratio of methane to manganese nitrate solution in the feed is 2:1; and the gas hourly space velocity (GHSV) is 12000 mL / (g·h) for the reaction (based on methane and oxygen).

[0051] Comparative Example 3

[0052] The reaction for the oxidative coupling of methane to produce C2 hydrocarbons was carried out according to the method of Example 3, except that manganese nitrate solution was not introduced into the inlet tube.

[0053] Example 4

[0054] The catalyst bed is filled with catalyst #4, with a bed height of 16 mm. The outlet of the inlet pipe is located above the catalyst bed, 35 mm from the top surface of the catalyst. During the reaction, a 5% (w / w) manganese nitrate solution is fed simultaneously with methane and oxygen through the inlet pipe. The reaction pressure is the pressure generated by the feed itself, i.e., 0.015 MPa; the reaction temperature is 830 °C; the volume ratio of methane to oxygen is 4:1; the volume ratio of methane to manganese nitrate solution in the feed is 1.5:1; and the gas hourly space velocity (GHSV) is 8000 mL / (g·h) based on methane and oxygen.

[0055] Comparative Example 4

[0056] The reaction for the oxidative coupling of methane to produce C2 hydrocarbons was carried out according to the method of Example 4, except that manganese nitrate solution was not introduced into the inlet tube.

[0057] Example 5

[0058] The reaction of oxidative coupling of methane to C2 hydrocarbons 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 reaction for the oxidative coupling of methane to C2 hydrocarbons 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 carried out the reaction of oxidative coupling of methane to C2 hydrocarbons according to the method of Example 1, except that the feed pipe of sodium tungstate solution was inserted 1 cm into the catalyst bed.

[0063] Example 8

[0064] The reaction for the oxidative coupling of methane to C2 hydrocarbons 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 Concentration of manganese nitrate solution (wt%) <![CDATA[Weight ratio of manganese nitrate to CH4]]> 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 reaction of oxidative coupling of methane to produce C2 hydrocarbons was carried out according to the method of Example 1, except that the volume ratio of manganese salt solution to methane was adjusted according to Table 3.

[0069] Table 3

[0070] serial number <![CDATA[Volume ratio of CH4 to manganese nitrate solution]]> <![CDATA[Weight ratio of manganese nitrate to CH4]]> 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 reaction of oxidative coupling of methane to C2 hydrocarbons was carried out according to the method of Example 1, except that the distance between the inlet pipe outlet and the catalyst bed was adjusted according to Table 4.

[0073] Table 4

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

[0075] Comparative Example 5

[0076] The reaction for the oxidative coupling of methane to produce C2 hydrocarbons was carried out according to the method of Example 1, except that the manganese nitrate solution was replaced with an equal amount of water.

[0077] Comparative Example 6

[0078] The reaction for the oxidative coupling of methane to C2 hydrocarbons was carried out according to the method of Example 1, except that manganese nitrate solution was not introduced into the feed pipe, but 4g of manganese nitrate particles were doped into the catalyst.

[0079] Test Example 1

[0080] The reaction products obtained after stabilization for 2 hours and 200 hours in the above examples and comparative examples were detected using a gas chromatograph (Agilent Technologies 7890A). The reaction products were analyzed using a dual-detection-channel, three-valve, four-column system, with the FID detector connected to an alumina column for analyzing CH4, C2H6, C2H4, C3H8, C3H6, and C4H. 10 C4H8, C n H m The TCD detector is mainly used to detect CO, CO2, N2, O2, and CH4. Then, the conversion rate of methane and CO are calculated using the following formula. x (CO+CO2) selectivity, C2 hydrocarbon selectivity and yield, the results are detailed in Table 5.

[0081] Methane conversion rate = Amount of methane consumed in the reaction / Initial amount of methane × 100%

[0082] Ethylene selectivity = Amount of methane consumed to produce ethylene / Total methane consumption × 100%

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

[0084] C2 hydrocarbon selectivity = ethane selectivity + ethylene selectivity

[0085] CO x Selectivity = Amount of methane consumed by both CO and CO2 generated / Total methane consumption × 100%

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

[0087] Table 5

[0088]

[0089] *Table 5 shows the methane conversion rate, C2 hydrocarbon selectivity, and CO2 conversion. x Selectivity refers to the data 2 hours after the reaction stabilizes.

[0090] 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 process for the production of a carbon dihydride, characterized by, The method comprises introducing CH4, O2 and a manganese salt solution into a reactor, the reactor cavity being filled with a catalyst, and performing a methane oxidative coupling reaction.

2. The method of claim 1, wherein, The manganese salt solution is introduced into the reactor by an introduction pipe, the distance between the outlet of the introduction pipe and the catalyst bed being 1-5 times the height of the catalyst bed.

3. The method of claim 2, wherein, The distance between the outlet of the introduction pipe and the catalyst bed is 1-3 times the height of the catalyst bed.

4. The method of claim 1, 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.

5. The method of claim 4, 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 1-150:

1.

6. The method of claim 1, wherein, The volume ratio of CH4 to the manganese salt solution is 0.5-4:

1. And / or, the concentration of the manganese salt solution is 0.5-8% by weight.

7. The method of claim 6, wherein, The volume ratio of CH4 to the manganese salt solution is 0.5-2:

1. And / or, the concentration of the manganese salt solution is 0.5-3% by weight.

8. The method of any one of claims 1-7, wherein, The manganese salt is selected from manganese nitrate and / or manganese acetate.

9. The method of claim 1, wherein, The conditions of the methane oxidative coupling reaction include: the volume ratio of CH4 to O2 is 2-10:1; the reaction temperature is 700-900℃; and the space time velocity of the reaction gas, calculated based on methane and oxygen, is 5000-15000 mL / (g·h).

10. The method of claim 9, wherein, The conditions of the methane oxidative coupling reaction include: the volume ratio of CH4 to O2 is 2-5:1; and the reaction temperature is 750-850℃.

11. Use of the method according to any one of claims 1-10 in improving the yield of carbon dihydrocarbons in a methane oxidative coupling reaction.

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