Process for the oxidative coupling of methane to produce carbon dihydric hydrocarbons, reactor and use thereof

Abstract

The present application relates to the field of methane oxidation coupling technology, and discloses a method for preparing carbon dihydrocarbon by methane oxidation coupling, a reactor and application thereof.The method provided by the present application effectively improves the selectivity and yield of carbon dihydrocarbon in the methane oxidation coupling reaction by introducing a tungstate solution and co-feeding CH4 and O2.The method is simple and easy to implement, 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 in different degrees for reactions catalyzed by various methane oxidation coupling catalysts, is universal, and has wide application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of methane oxidation coupling technology, in particular, to a method for preparing carbon dihydrocarbon by methane oxidation coupling, a reactor and their applications. BACKGROUND

[0002] Natural gas is a kind of resource with rich reserves and green and clean, but the effective utilization rate of natural gas resource is not high at present. About 70-90% of the components in natural gas is methane. The energy consumption required for direct conversion of methane is low, and there are advantages such as short process flow and low cost. In the direct method, methane oxidation coupling reaction for preparing C2 hydrocarbon can provide high value chemical raw materials such as ethylene, which has been one of the hotspots widely studied and concerned by researchers.

[0003] Since the methane oxidation coupling route was first proposed in 1982, after more than 30 years, a large amount of work has been done by numerous scientists in improving the performance of catalysts. However, due to the great difficulty in activation and directional conversion of methane, so far, no industrial application device has been developed. As a gas with stable chemical properties, methane has a high activation energy, and even under aerobic conditions, it still needs a high temperature to participate in the coupling reaction, and the C2 hydrocarbon yield is still not ideal. Moreover, due to the high temperature of the methane oxidation coupling reaction, with the extension of the reaction time, the activity of the catalyst decreases, and the yield of C2 hydrocarbon further decreases. Therefore, it is urgent to develop a method and device that can improve the yield of C2 hydrocarbon in the methane oxidation coupling reaction. SUMMARY

[0004] The purpose of the present application is to overcome the problems in the prior art, such as the low yield of carbon dihydrocarbon in the preparation of carbon dihydrocarbon by methane oxidation coupling, and the difficulty in realizing industrial application, and to provide a method for preparing carbon dihydrocarbon by methane oxidation coupling, a reactor and their applications. The method provided by the present application effectively improves the yield of carbon dihydrocarbon in the methane oxidation coupling reaction by introducing a tungstate solution and reaction gas as a co-feed, which lays a foundation for the industrial application of methane oxidation coupling for preparing carbon dihydrocarbon.

[0005] In order to achieve the above-mentioned purpose, the present application provides a method for preparing carbon dihydrocarbon by methane oxidation coupling, which comprises: introducing CH4, O2 and a tungstate solution into a reactor to carry out a methane oxidation coupling reaction.

[0006] The second aspect of the present application provides a methane oxidation coupling reactor, which comprises a reactor cavity and an introduction pipe, the introduction pipe is used for introducing a tungstate solution into the reactor cavity, and the outlet of the introduction pipe is arranged above the catalyst bed layer in the reactor cavity.

[0007] The third aspect of the present application provides the method of the first aspect, and / or the application of the reactor of the second aspect in improving the yield of carbon dihydrocarbon in the methane oxidation coupling reaction.

[0008] By means of the technical scheme, the present application can achieve the following beneficial effects:

[0009] (1) The method provided by the present application can effectively improve the selectivity and yield of carbon dihydrocarbon in the methane oxidative coupling reaction, and can be stably operated 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 application is simple and easy to operate, and has universality in the methane oxidative coupling reaction, which can be applied to various methane oxidative coupling catalysts catalyzed reactions, and greatly improves the selectivity and yield of carbon dihydrocarbon.

[0011] (3) The device provided by the present application has simple structure, which can be obtained by simple modification of the existing reactor, and has the advantages of low cost and easy to obtain. DETAILED DESCRIPTION

[0012] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the present application. The endpoints of the ranges and any numerical values are to be understood as approximations. The ranges and values are to be understood to encompass values approximating the value.

[0013] In the present application, "carbon dihydrocarbon" and "C2 hydrocarbon" have the same meaning and can be used interchangeably. It refers to ethane and / or ethylene.

[0014] The inventors of the present application ingeniously found in the research that by adding tungstate solution (for example, co-feeding with reaction gas containing methane and oxygen) in the process of methane oxidative coupling reaction, the selectivity and yield of carbon dihydrocarbon can be effectively improved.

[0015] Based on this, the present application provides a method for preparing carbon dihydrocarbon by methane oxidative coupling, which comprises: introducing CH4, O2 and tungstate solution into a reactor to carry out methane oxidative coupling reaction.

[0016] According to the preferred embodiments of the present application, the tungstate 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 1-4 times the height of the catalyst bed. The distance between the outlet of the introduction pipe and the catalyst bed refers to the distance between the outlet of the introduction pipe and the top surface of the catalyst after the reactor is filled with the catalyst, and the height of the catalyst bed refers to the height of the catalyst filled in the reactor. For example, the distance between the outlet of the introduction pipe and the catalyst bed can be 16-64 mm, i.e. the distance between the plane where the outlet of the introduction pipe is located and the upper surface of the catalyst bed after the reactor is filled with the catalyst can be 16-64 mm, with respect to a catalyst bed with a filling height of 16 mm.

[0017] In the present application, the specific amount of the tungstate solution, the concentration and the type of the tungstate solution are not particularly limited, as long as the selectivity and yield of the carbon dihydrocarbon in the methane oxidative coupling reaction can be improved to a relatively ideal level.

[0018] According to some preferred embodiments of the present application, the amount of the tungstate solution is such that the weight ratio of tungstate to CH4 introduced per unit time is 3-100:1, preferably 3-50:1. For example, the weight ratio of tungstate to CH4 introduced per unit time can be 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, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, 100:1, or any intermediate ratio within the range formed by any two of the above ratios.

[0019] According to the preferred embodiments of the present application, the volume ratio of CH4 to the tungstate solution is 0.2-3:1, preferably 0.5-2:1.

[0020] According to the preferred embodiments of the present application, the concentration of the tungstate solution is 0.5-5 wt%, preferably 0.5-2 wt%.

[0021] In the method provided by the present application, a solution prepared by using a water-soluble tungstate is preferably used. According to some preferred embodiments of the present application, the tungstate is selected from sodium tungstate and / or potassium tungstate.

[0022] The method provided by the present application can be used in methane oxidative coupling reactions catalyzed by various catalysts to improve the selectivity and yield of carbon dihydrocarbon, and thus the present application can be applied to a wide range of conditions of methane oxidative coupling reactions, which can be determined according to the type of the catalyst used and the reaction conditions suitable for the catalyst.

[0023] According to some preferred embodiments of the present application, the conditions of the methane oxidative coupling reaction include: the volume ratio of CH4 and O2 is 2-10:1, preferably 2-5:1; the reaction temperature is 700-900℃, preferably 700-830℃; the space-time velocity of the reaction gas (CH4+O2) is 5000-25000 mL / (g·h).

[0024] In the method provided by the present application, the pressure of the reaction is not particularly limited and does not need to be adjusted intentionally, and the pressure of the raw materials can be used generally. 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 application provides a methane oxidative coupling reactor, which comprises a reactor cavity and an introduction pipe for introducing a tungstate 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 preferred embodiments of the present application, the distance between the outlet of the introduction pipe and the catalyst bed is 1-4 times the height of the catalyst bed.

[0027] According to preferred embodiments of the present application, the introduction pipe is arranged at the central position 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 preferred embodiments of the present application, the ratio of the inner diameters of the reactor cavity and the introduction pipe is 4-10:1.

[0029] According to preferred embodiments of the present application, the reactor cavity is filled with catalyst.

[0030] Preferably, the reactor cavity is filled with a packing material at both ends of the catalyst, and the packing material is preferably an inert material. The "inert material" refers to a substance that has no reaction activity in the methane oxidative coupling reaction, such as alumina, silica (e.g., quartz sand), etc.

[0031] The present application does not have particular limitations on the specific material and size of the reactor, and any reactor that can be used for the methane oxidative coupling reaction in the art and has the aforementioned characteristics belongs to the content protected by the present application. For example, the reactor provided by the present application can be a quartz material.

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

[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] The catalysts used in the following examples were prepared according to the following method:

[0036] 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.

[0037] Table 1

[0038]

[0039] Note: The content of each active component in the catalyst is a relative content calculated based on 100g of support.

[0040] In the following embodiments, unless otherwise specified, the reactor used includes a quartz reaction chamber and an inlet pipe inserted along the center (central axis) of the reaction chamber. The inlet pipe has an outer diameter of 3 mm and a thickness of 0.9 mm. The quartz reaction chamber has an inner diameter of 10 mm, a length of 530 mm, a thickness of 1.5 mm, a catalyst loading of 0.4 g, and a layer height of 16 mm.

[0041] Example 1

[0042] The catalyst bed is filled with catalyst #1. 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 1% (w / w) sodium tungstate 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., 0.02 MPa; the reaction temperature is 800 °C; the volume ratio of methane to oxygen is 2:1; the volume ratio of methane to sodium tungstate solution in the feed is 1:1; and the gas hourly space velocity (GHSV) is 10000 mL / (g·h) for the reaction, calculated as methane and oxygen.

[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 sodium tungstate solution was not introduced into the inlet tube.

[0045] Example 2

[0046] The catalyst bed is filled with catalyst #2. 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% potassium tungstate 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., 0.02 MPa, the reaction temperature is 780℃, the volume ratio of methane to oxygen is 2.5:1, the volume ratio of methane to potassium tungstate solution in the feed is 0.6:1, 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 potassium tungstate solution was not introduced into the inlet tube.

[0049] Example 3

[0050] The catalyst bed is filled with catalyst #3. 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) sodium tungstate 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., 0.02 MPa; the reaction temperature is 830 °C; the volume ratio of methane to oxygen is 3:1; the volume ratio of methane to sodium tungstate solution in the feed is 2:1; and the gas hourly space velocity (GHSV) for the reaction (based on methane and oxygen) is 12000 mL / (g·h).

[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 sodium tungstate solution was not introduced into the inlet tube.

[0053] Example 4

[0054] The catalyst bed was filled with catalyst #4. The outlet of the inlet pipe was located above the catalyst bed, 50 mm from the top surface of the catalyst. During the reaction, a 5% (w / w) potassium tungstate solution was fed simultaneously with methane and oxygen through the inlet pipe. The reaction pressure was the pressure generated by the feedstock itself, i.e., 0.02 MPa; the reaction temperature was 810 °C; the volume ratio of methane to oxygen was 4:1; the volume ratio of methane to potassium tungstate solution in the feed was 1.5:1; and the gas hourly space velocity (GHSV) for the reaction, calculated as methane and oxygen, was 8000 mL / (g·h).

[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 potassium tungstate solution was not introduced into the inlet tube.

[0057] Example 5

[0058] 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 sodium tungstate solution was 15% by weight.

[0059] Example 6

[0060] 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 methane to sodium tungstate solution was 8:1.

[0061] Example 7

[0062] The reaction for the oxidative coupling of methane to C2 hydrocarbons was carried out according to the method of Example 1, except that the feed pipe of the sodium tungstate solution was inserted 1 cm into the catalyst bed.

[0063] Example 8

[0064] 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 concentration of the tungstate solution was adjusted according to Table 2.

[0065] Table 2

[0066] No. Sodium tungstate solution concentration (wt%) The weight ratio of sodium tungstate to CH4 8-1 0.5 7:1 8-2 1.5 21.1:1 8-3 2 28.2:1 8-4 3 42.3:1 8-5 5 70.4:1 8-6 0.3 4.2:1

[0067] Example 9

[0068] 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 tungstate solution to methane was adjusted according to Table 3.

[0069] Table 3

[0070] No. volume ratio of CH4 to sodium tungstate solution The weight ratio of sodium tungstate to CH4 9-1 0.1:1 140.8:1 9-2 0.2:1 70.4:1 9-3 0.5:1 28.2:1 9-4 3:1 4.7:1 9-5 5:1 2.8:1

[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] No. Distance from inlet of introduction tube to catalyst bed (mm) 10-1 10 10-2 30 10-3 64 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 sodium tungstate solution was replaced with an equal amount of water.

[0077] Comparative Example 6

[0078] The reaction of oxidative coupling of methane to C2 hydrocarbons was carried out according to the method of Example 1, except that sodium tungstate solution was not introduced into the feed pipe, but 2.5g of sodium tungstate particles were doped into the catalyst.

[0079] Test Example 1

[0080] The reaction products obtained after stabilization for 2 h and 200 h in the above examples and comparative examples were detected using a gas chromatograph (Agilent, 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. The conversion rate of methane, COx selectivity, C2 hydrocarbon selectivity, and yield were calculated using the following formulas, and 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] C2 hydrocarbon yield = methane conversion rate × (ethane selectivity + ethylene selectivity)

[0086] CO x (CO + CO2) selectivity = (Amount of methane consumed by the combined generation of CO and CO2) / (Total methane consumption) × 100%

[0087] Table 5

[0088]

[0089] *Table 5 shows the methane conversion, 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 oxidative coupling of methane to produce a carbon dihydrocarbon, characterized in that, The method comprises introducing CH4, O2 and a tungstate solution into a reactor, the reactor cavity being filled with a catalyst, and carrying out a methane oxidative coupling reaction.

2. The method of claim 1, wherein, The tungstate solution is introduced into the reactor through an introduction pipe, the distance between the outlet of the introduction pipe and the catalyst bed being 1-4 times the height of the catalyst bed.

3. The method of claim 1, wherein, The amount of the tungstate solution is such that the weight ratio of tungstate to CH4 introduced per unit time is 3-100:

1.

4. The method of claim 3, wherein, The amount of the tungstate solution is such that the weight ratio of tungstate to CH4 introduced per unit time is 3-50:

1.

5. The method of claim 1, wherein, The volume ratio of CH4 to the tungstate solution is 0.2-3:

1. And / or, the concentration of the tungstate solution is 0.5-5% by weight.

6. The method of claim 5, wherein, The volume ratio of CH4 to the tungstate solution is 0.5-2:

1. And / or, the concentration of the tungstate solution is 0.5-2% by weight.

7. The method of any of claims 1-6, wherein, The tungstate is selected from sodium tungstate and / or potassium tungstate.

8. 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 5000-25000 mL / (g·h).

9. The method of claim 8, 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 700-830℃.

10. Use of the method according to any one of claims 1-9 in improving the carbon dihydrocarbon yield of a methane oxidative coupling reaction.

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