Catalyst, reactor and process for the production of carbon dihydrocarbons

Abstract

The application relates to the technical field of methane oxidation coupling reaction, and discloses a catalyst, a reactor and a method for preparing carbon dihydrocarbon. The catalyst provided by the application has the advantages of high reaction activity, high methane conversion rate and high C2 hydrocarbon yield, and the one-way C2 hydrocarbon yield can be further improved by combining the preferred preparation method of the application. Under the preferred reaction process conditions of the application, the reactor of the application and the preferred reaction conditions of the application can achieve excellent reaction effects with the methane conversion rate and the C2 hydrocarbon selectivity both reaching more than 40%.

Description

Technical Field

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

[0002] Ethylene is a fundamental raw material in the petrochemical industry, and its output, production scale, and production technology are important indicators of a country's petrochemical level. With increasing global demand for ethylene, its capacity and output have continued to grow. Currently, ethylene is mainly produced from naphtha steam cracking. However, due to the reliance on naphtha as a primary source of petroleum processing, it is heavily influenced by petroleum economics and prices. Therefore, developing new routes for ethylene production from non-petroleum resources such as methane, expanding the sources of raw materials for ethylene production, and reducing dependence on petroleum resources is of significant academic and practical value.

[0003] Oxidative coupling of methane (OCM) is a technical route for activating methane under aerobic conditions to directly produce ethane and ethylene. The concept of OCM was first proposed by Keller et al. in 1982, nearly 40 years ago. Despite extensive research, there are still no successful industrial applications of OCM worldwide. The key to its application lies in achieving high single-pass yields of C2 hydrocarbons. However, the current catalysts and production methods still yield unsatisfactory C2 hydrocarbons, failing to meet the needs of industrial applications. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of unsatisfactory single-pass yield of C2 hydrocarbons in the existing technology of methane oxidative coupling reaction, and to provide a catalyst, reactor, and method for preparing C2 hydrocarbons. The catalyst provided by this invention has the advantages of high reactivity, high methane conversion rate, and high C2 hydrocarbon yield. Combined with the preferred preparation method of this invention, the single-pass yield of C2 hydrocarbons can be further improved.

[0005] To achieve the above objectives, the present invention provides a method for preparing a catalyst for the direct oxidation of methane to C2 hydrocarbons. The method includes mixing a cristobalite support, an active component precursor, a molding agent, and water to form a shaped plastic body, and then subjecting the shaped plastic body to a first drying and a first calcination in sequence to obtain the catalyst for the direct oxidation of methane to C2 hydrocarbons.

[0006] The active component precursor includes a tungsten precursor and / or a manganese precursor.

[0007] A second aspect of the present invention provides a catalyst for the direct oxidation of methane to C2 hydrocarbons, said catalyst being prepared according to the method described above;

[0008] Alternatively, the catalyst may comprise a quartz support and an active component supported on the quartz support, the active component being selected from W, Mn, and alkali metals.

[0009] A third aspect of the present invention provides a reactor for a methane oxidative coupling reaction, the reactor comprising a reactor cavity made of quartz and a catalyst and a packing agent filled in the cavity;

[0010] Wherein, the catalyst is the catalyst described above;

[0011] The particle size of the filler does not exceed 1 / 3 of the catalyst size.

[0012] A fourth aspect of the present invention provides a method for preparing C2 hydrocarbons, the method comprising introducing a reaction gas containing CH4 and O2 into a reactor to carry out a methane oxidative coupling reaction;

[0013] The reactor in question is the same as described above.

[0014] Through the above technical solution, the present invention can achieve the following beneficial effects:

[0015] (1) The catalyst provided by this invention is a molded catalyst, which can be directly applied to industrial production, avoiding the influence of the catalyst molding process on its catalytic effect. In addition, this catalyst has the advantages of high catalytic activity, high methane conversion rate, and high C2 hydrocarbon yield.

[0016] (2) The reactor provided by the present invention simultaneously fills the reactor cavity with catalyst and packing agent. The small particle size packing agent further fills the voids in the reactor cavity, reducing the adverse effects of free radical elimination reaction on the OCM reaction effect, and further improving the yield and selectivity of C2 hydrocarbons.

[0017] (3) The molding catalyst provided by the present invention, combined with the C2 hydrocarbon preparation method provided by the present invention, has the characteristics of clean production, cheap and readily available raw materials, low processing cost, simplified process, and easy to realize industrial production.

[0018] (4) The molding catalyst provided by this invention, combined with the C2 hydrocarbon preparation method provided by this invention, can achieve a high C2 hydrocarbon yield and has good catalytic stability. Small-scale tests have confirmed that, under the preferred reaction conditions, using the reactor of this invention and following the preferred reaction conditions of this invention, excellent reaction results with methane conversion and C2 hydrocarbon selectivity both exceeding 40% can be obtained. Detailed Implementation

[0019] 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.

[0020] In this invention, the terms "first" and "second" in "first drying," "second drying," "first roasting," and "second roasting" are only used to distinguish the drying and roasting operations in different steps in the description, and they do not limit the specific operation methods, sequences, etc.

[0021] In this invention, "C2 hydrocarbon" is an abbreviation for "carbon dihydrocarbon," and the two have the same meaning and can be used interchangeably.

[0022] The present invention provides a method for preparing a catalyst for the direct oxidation of methane to C2 hydrocarbons. The method includes mixing and molding a cristobalite support, an active component precursor, a molding agent and water to obtain a molded plastic body, and then subjecting the molded plastic body to a first drying and a first calcination in sequence to obtain the catalyst for the direct oxidation of methane to C2 hydrocarbons.

[0023] The active component precursor includes a tungsten precursor and / or a manganese precursor.

[0024] In the method provided by this invention, there are no particular limitations on the precursor of the active component. According to a preferred embodiment of the invention, the precursor of the active component is a water-soluble acid and / or a water-soluble salt of the active component, such as tungstate (salt), nitrate, etc. To avoid introducing impurities into the catalyst and affecting its catalytic performance / stability, the method provided by this invention does not use salts containing other elements, such as sulfates and chlorides of the active component, as precursors. According to a preferred embodiment of the invention, the precursor of the active component is selected from at least one of sodium tungstate, potassium tungstate, ammonium tungstate, and manganese nitrate.

[0025] In the method provided by this invention, there is no particular limitation on the amount of the active component precursor. To obtain an OCM-shaped catalyst with better catalytic activity (e.g., higher methane conversion, better C2 hydrocarbon selectivity), according to a preferred embodiment of this invention, the amount of tungsten precursor used is 5-25 parts by weight compared to 100 parts by weight of the support based on SiO2. Preferably, it is 5-20 parts by weight. More preferably, it is 7-12 parts by weight.

[0026] According to a preferred embodiment of the present invention, the amount of manganese precursor used is 5-30 parts by weight compared to 100 parts by weight of the carrier based on SiO2. Preferably, it is 5-28 parts by weight. More preferably, it is 8-15 parts by weight.

[0027] In this invention, there are no particular limitations on the forming agent. It can be any reagent that is added to the catalyst forming process in the preparation of OCM forming catalysts, and its specific type and amount can be adjusted according to the actual situation.

[0028] According to a preferred embodiment of the present invention, the molding agent is selected from self-extruding agents and / or binders.

[0029] Preferably, the extrusion aid is selected from guar gum powder and / or starch.

[0030] Preferably, the binder is selected from water glass. More preferably, it is water glass with a specific gravity of 1.35-1.45 and a modulus of 1.5-2.

[0031] According to a preferred embodiment of the present invention, the amount of molding agent used is 5-45 parts by weight compared to 100 parts by weight of carrier based on SiO2. The "amount of molding agent" refers to the total amount of all molding agents used (e.g., binders, extrusion aids, etc.).

[0032] Preferably, the amount of extrusion aid is 5-25 parts by weight compared to 100 parts by weight of carrier based on SiO2. More preferably, it is 5-20 parts by weight. More preferably, it is 8-12 parts by weight.

[0033] Preferably, the amount of binder is 5-20 parts by weight compared to 100 parts by weight of the carrier based on SiO2. More preferably, it is 5-18 parts by weight. More preferably, it is 8-10 parts by weight.

[0034] According to a preferred embodiment of the present invention, the total amount of water used is 120-180 parts by weight compared to 100 parts by weight of the carrier based on SiO2. "Total amount of water used" refers to the total amount of water used in the mixing process, including the water used to prepare the active component precursor solution, as well as the water added during the mixing process.

[0035] According to a preferred embodiment of the present invention, the molding method results in a molded plastic body with dimensions of 3-7 mm in diameter and 3-6 mm in length. Preferably, the aspect ratio of the molded plastic body is 1:1-2. For example, it can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2, or any intermediate value between any two of the above ratios.

[0036] In the method provided by this invention, the mixing can be carried out using any method existing in the art. To ensure uniform mixing of the raw materials and to make the viscosity of the plastic body obtained from the subsequent kneading process more conducive to extrusion into strips (molding), thereby making the molded plastic body more suitable for subsequent drying and calcination, and more conducive to forming a molding catalyst with better specific surface area, pore structure, and strength, preferably, the mixing process can be carried out by grinding, sieving, stirring, etc., followed by kneading of the mixed materials. Stirring is preferred; for example, mixing can be carried out under stirring conditions of 50-150 rpm. Furthermore, to obtain better kneading results, the kneading operation in this invention can be performed for 15-60 minutes.

[0037] In this invention, there are no particular limitations on the molding method. According to a preferred embodiment of the invention, the molding method is selected from extrusion molding and / or spray molding, with extrusion molding being preferred.

[0038] During their research, the inventors of this invention discovered that when preparing OCM molding catalysts by extrusion molding, using specific molding conditions not only makes it easier to extrude the plastic body into strips, but also enables the production of molding catalysts with better mechanical strength, specific surface area, and pore structure.

[0039] According to a preferred embodiment of the present invention, the molding conditions include: extrusion rate of 100-500 rpm, temperature of 10-30°C, and pressure of 10-30 MPa.

[0040] To further improve the strength of the shaped catalyst, according to a preferred embodiment of the present invention, the first drying method is selected from drying and / or vacuum drying, preferably carried out by step drying.

[0041] Preferably, the step-by-step drying method includes:

[0042] (1) Low temperature drying: temperature 20-40℃, time 2-6h;

[0043] (2) High temperature drying: temperature 100-160℃, time 4-10h.

[0044] According to a preferred embodiment of the present invention, the first calcination method includes: heating to 750-900°C at a heating rate of 4-10°C / min, and then calcining at that temperature for 6-10 hours.

[0045] According to a preferred embodiment of the present invention, the method further includes the step of preparing a quartz support: mixing SiO2 and sodium salt (in the presence of water) and then subjecting the mixture to a second drying and a second calcination.

[0046] Any SiO2 available in the art for the preparation of OCM catalysts (supports) is applicable to this invention. It can be a commercially available product or a product prepared using existing technology. Preferably, the SiO2 is SiO2 particles (e.g., amorphous spherical particles) with an average particle size of 0.05-0.18 mm. More preferably, it is 0.08-0.15 mm.

[0047] Preferably, the sodium salt is selected from sodium nitrate and / or sodium tungstate.

[0048] Preferably, the weight ratio of SiO2 to sodium salt is 10-50:1.

[0049] Preferably, the conditions for the second drying include: a temperature of 80-150°C and a time of 5-10 hours.

[0050] Preferably, the conditions for the second calcination include: heating to 800-900°C at a heating rate of 3-10°C / min, and then calcining at that temperature for 5-12 hours.

[0051] A second aspect of the present invention provides a catalyst for the direct oxidation of methane to C2 hydrocarbons, said catalyst being prepared according to the method described above;

[0052] Alternatively, the catalyst may comprise a quartz support and an active component supported on the quartz support, the active component being selected from W, Mn, and alkali metals.

[0053] Preferably, in the catalyst, the W content is 5-18.5% by weight, based on the weight of SiO2 in the cristobalite support. More preferably, it is 5.5-15% by weight. More preferably, it is 8-10% by weight.

[0054] Preferably, in the catalyst, based on the weight of SiO2 in the cristobalite support, the Mn content is 1-10% by weight. More preferably, it is 1.5-9% by weight. More preferably, it is 2-4% by weight.

[0055] Preferably, the alkali metal content in the catalyst is 0.5-5% by weight, based on the weight of SiO2 in the cristobalite support. More preferably, it is 0.8-4% by weight. More preferably, it is 1.5-3% by weight.

[0056] It should be noted that the W and alkali metal contents mentioned above refer to the total W and alkali metal contents supported on the cristobalite support and (possibly present) in the cristobalite support.

[0057] It should be noted that the W in the catalyst provided by the present invention can exist in the form of elemental W or tungstate (e.g., tungstic acid and / or tungstate) when exerting catalytic effect. It is written as W in the present invention only for the convenience of description and calculation of the content and ratio of active components.

[0058] Preferably, the catalyst has the following dimensions: diameter 3-7 mm, length 3-6 mm. More preferably, the aspect ratio of the catalyst is 1:1-2.

[0059] Preferably, the mechanical strength of the catalyst is not less than 20 N / particle. More preferably, it is 25-30 N / particle.

[0060] A third aspect of the present invention provides a reactor for a methane oxidative coupling reaction, the reactor comprising a reactor cavity made of quartz and a catalyst and a packing agent filled in the cavity;

[0061] Wherein, the catalyst is the catalyst described above;

[0062] The particle size of the filler does not exceed 1 / 3 of the catalyst size.

[0063] It should be noted that when the catalyst is a regular sphere, the catalyst size refers to its diameter; when the catalyst is not spherical, the catalyst size refers to its equivalent diameter. The equivalent diameter refers to the diameter of a non-spherical particle that has been converted into a spherical shape using an equivalent method, and this converted spherical diameter represents the particle size. Common equivalent methods include the equal volume method, the equal surface area method, the equal projected area method, and the equal projected perimeter method. This invention does not impose any particular restrictions on the specific choice of equivalent method; it can be selected according to the actual situation and needs.

[0064] It should be noted that the present invention does not impose any particular limitation on the shape of the filler; it can be any shape, such as spherical particles, circular flake particles, or amorphous particles. The present invention selects fillers suitable for loading into the reactor provided by the present invention by choosing a sieve that meets the above-mentioned particle size conditions according to the size of the catalyst.

[0065] According to a preferred embodiment of the present invention, the length-to-diameter ratio of the reactor cavity is 15-40, and the ratio of the inner diameter of the reactor cavity to the size of the catalyst is 5-8:1.

[0066] According to a preferred embodiment of the present invention, the particle size of the filler is 1 / 10 to 1 / 3 of the size of the catalyst.

[0067] Preferably, the filler is selected from α-Al₂O₃ with a particle size not exceeding 1 mm. That is, the α-Al₂O₃ can pass through a sieve of 18 mesh or larger.

[0068] More preferably, the filler is selected as α-Al2O3 with a particle size of 0.4-1 mm. That is, the α-Al2O3 can pass through an 18-mesh sieve, but cannot pass through a 50-mesh sieve.

[0069] Preferably, the weight ratio of catalyst to packing agent in the reactor cavity is 10-20:1.

[0070] A fourth aspect of the present invention provides a method for preparing C2 hydrocarbons, the method comprising introducing a reaction gas containing CH4 and O2 into a reactor to carry out a methane oxidative coupling reaction;

[0071] The reactor in question is the same as described above.

[0072] According to a preferred embodiment of the present invention, the volume ratio of CH4 to O2 is 2-6:1.

[0073] According to a preferred embodiment of the present invention, the conditions for the methane oxidative coupling reaction include: a reaction temperature of 750-850°C in the catalyst section and a gas hourly space velocity of 9000-15000 mL·g. -1 ·h -1 .

[0074] Preferably, the reaction time for the methane oxidative coupling reaction is 0.5-25 h, and more preferably 5-20 h.

[0075] 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.

[0076] In the following examples, SiO2 was purchased from Qingdao Ocean Chemical Plant and consisted of amorphous spherical particles with an average particle size of 0.1 ± 0.05 mm. Tianqing powder (soluble guar gum powder, loose powder) was purchased from Hubei Yuying Biotechnology Co., Ltd. Unless otherwise specified, all chemicals used in the other examples were purchased from reputable chemical reagent suppliers and were of chemical purity.

[0077] In the following examples, a twin-screw extruder (F-26 type) purchased from the South China University of Technology Science and Technology Industrial Plant was used to prepare the molding catalyst.

[0078] Example 1

[0079] (1) Preparation of quartz support: 6g sodium tungstate was added to 150g distilled water and completely dissolved. Then, 100g SiO2 was added and impregnated for 2 hours. The mixture was then dried at 120℃ for 6 hours. The dried product was placed in a muffle furnace and calcined at 850℃ for 10 hours in air at a heating rate of 5℃ / min to obtain support A1.

[0080] (2) Preparation of the molded plastic body:

[0081] (a) The carrier A1 was mixed with 8g sodium tungstate, 10g manganese nitrate, 10g water glass (specific gravity 1.35, modulus 1.5), 10g starch and 25g deionized water (stirred at 100rpm for 35min) to obtain the plastic body B1.

[0082] (b) Using an extruder, plastic body B1 is extruded through a perforated plate with a diameter of 4 mm, and extruded into a long solid cylinder at an extrusion rate of 100 rpm, a temperature of 30 °C, and a pressure of 15 MPa. The cylinder is then cut into granules with a length of 3 mm to obtain the molded plastic body C1.

[0083] (3) Preparation of the molding catalyst:

[0084] The molded plastic body C1 is dried:

[0085] (A) First drying: temperature 20℃, time 6h;

[0086] (B) Second drying: temperature 100℃, time 8h, to obtain the dried product.

[0087] The dried product was placed in a muffle furnace and calcined in air at a heating rate of 4 °C / min to 750 °C for 10 h. Molded catalyst-1 was obtained.

[0088] Methane oxidative coupling reaction: The catalytic reactor is a quartz tube with an inner diameter of 20 mm and a length of 800 mm. 10 g of molded catalyst-1 and 1 g of α-Al2O3 with a particle size of 0.4±0.05 mm (which can pass through a 35-mesh sieve but not a 50-mesh sieve) are mixed evenly and packed into the catalyst bed of the reaction tube.

[0089] A feed gas consisting of methane and oxygen (volume ratio 3:1) was mixed and introduced at the top of the reaction tube. The reaction pressure was the pressure generated by the feed gas itself (0.02 MPa). The reaction temperature in the catalyst section was controlled at 805 °C, and the gas hourly space velocity (GHSV) was 9000 mL·g⁻¹. -1 ·h -1 .

[0090] Example 2

[0091] (1) Preparation of quartz support: 3g sodium tungstate was added to 160g distilled water and completely dissolved. Then, 100g SiO2 was added and impregnated for 2 hours. The mixture was then dried at 120℃ for 6 hours. The dried product was placed in a muffle furnace and calcined at 850℃ for 10 hours in air at a heating rate of 5℃ / min to obtain support A2.

[0092] (2) Preparation of the molded plastic body:

[0093] (a) Mix carrier A2 with 6g sodium tungstate, 5g manganese nitrate, 5g water glass (specific gravity 1.4, modulus 1.8), 5g starch and 10g deionized water (stir at 60 rpm for 55 min) to obtain plastic body B2.

[0094] (b) Using an extruder, plastic body B2 is extruded through a perforated plate with a diameter of 5 mm, and extruded into a long solid cylinder at an extrusion rate of 200 rpm, a temperature of 10 °C, and a pressure of 15 MPa. The cylinder is then cut into granules with a length of 4 mm to obtain the molded plastic body C2.

[0095] (3) Preparation of the molding catalyst:

[0096] The molded plastic body C2 is dried:

[0097] (A) First drying: temperature 40℃, time 4h;

[0098] (B) Second drying: temperature 120℃, time 6h, to obtain dried product.

[0099] The dried product was placed in a muffle furnace and calcined at 850°C for 8 hours under air atmosphere at a heating rate of 5°C / min. Molded catalyst-2 was obtained.

[0100] Methane oxidative coupling reaction: The catalytic reactor is a quartz tube with an inner diameter of 25 mm and a length of 800 mm. 10 g of molded catalyst-2 and 0.7 g of α-Al2O3 with a particle size of 0.6 ± 0.05 mm (which can pass through a 25-mesh sieve but not a 35-mesh sieve) are mixed evenly and packed into the catalyst bed of the reaction tube.

[0101] A feed gas consisting of methane and oxygen (volume ratio 2.5:1) was mixed and introduced at the top of the reaction tube. The reaction pressure was the pressure generated by the feed gas itself (0.020 MPa). The reaction temperature in the catalyst section was controlled at 790 °C, and the gas hourly space velocity (GHSV) was 10000 mL·g⁻¹. -1 ·h -1 .

[0102] Example 3

[0103] (1) Preparation of cubic quartz: 9g sodium tungstate was added to 120g distilled water and completely dissolved. Then 100g SiO2 was added and impregnated for 2 hours. After drying at 120℃ for 6 hours, the dried product was placed in a muffle furnace and heated to 850℃ at a heating rate of 5℃ / min under air atmosphere. After calcination for 10 hours, A3 was obtained.

[0104] (2) Preparation of the molded plastic body:

[0105] (a) Mix carrier A3 with 15g sodium tungstate, 16g manganese nitrate, 18g water glass (specific gravity 1.45, modulus 2), 15g starch and 10g deionized water (stir at 120rpm for 45min) to obtain plastic body B3.

[0106] (b) Using an extruder, plastic body B3 is extruded through a perforated plate with a diameter of 3 mm, and extruded into a long solid cylinder at an extrusion rate of 300 rpm, a temperature of 20 °C, and a pressure of 15 MPa. The cylinder is then cut into granules with a length of 3 mm to obtain the molded plastic body C3.

[0107] (3) Preparation of the molding catalyst:

[0108] The molded plastic body C3 is dried:

[0109] (A) First drying: temperature 30℃, time 6h;

[0110] (B) Second drying: temperature 150℃, time 4h, to obtain dried product.

[0111] The dried product was placed in a muffle furnace and calcined in air at a heating rate of 6 °C / min to 880 °C for 10 h. Molded catalyst-3 was obtained.

[0112] Methane oxidative coupling reaction: The catalytic reactor is a quartz tube with an inner diameter of 20 mm and a length of 700 mm. 10 g of molded catalyst-3 and 0.5 g of α-Al2O3 with a particle size of 0.8 ± 0.05 mm (which can pass through a 20-mesh sieve but not a 24-mesh sieve) are mixed evenly and packed into the catalyst bed of the reaction tube.

[0113] A feed gas consisting of methane and oxygen (volume ratio 6:1) was mixed and introduced at the top of the reaction tube. The reaction pressure was the pressure generated by the feed itself (0.020 MPa). The reaction temperature in the catalyst section was controlled at 830 °C, and the gas hourly space velocity (GHSV) was 15000 mL·g⁻¹. -1 ·h -1 .

[0114] Example 4

[0115] (1) Preparation of quartz support: 3g sodium tungstate was added to 120g distilled water and completely dissolved. Then 100g SiO2 was added and impregnated for 2 hours. After drying at 120℃ for 6 hours, the dried product was placed in a muffle furnace and heated to 850℃ at a heating rate of 5℃ / min under air atmosphere. After calcination for 10 hours, support A4 was obtained.

[0116] (2) Preparation of the molded plastic body:

[0117] (a) The carrier A1 was mixed with 20g sodium tungstate, 28g manganese nitrate, 12g water glass (specific gravity 1.4, modulus 1.6), 18g guar gum powder and 10g deionized water (stirred at 100rpm for 35min) to obtain the plastic body B4.

[0118] (b) Using an extruder, plastic body B4 is extruded through a perforated plate with a diameter of 5 mm, and extruded into a long solid cylinder at an extrusion rate of 150 rpm, a temperature of 30 °C, and a pressure of 15 MPa. The cylinder is then cut into granules with a length of 3 mm to obtain the molded plastic body C4.

[0119] (3) Preparation of the molding catalyst:

[0120] The molded plastic body C4 is dried:

[0121] (A) First drying: temperature 20℃, time 6h;

[0122] (B) Second drying: temperature 120℃, time 8h, to obtain dried product.

[0123] The dried product was placed in a muffle furnace and calcined in air at a heating rate of 5 °C / min to 800 °C for 10 h. Molded catalyst-4 was obtained.

[0124] Methane oxidative coupling reaction: The catalytic reactor is a quartz tube with an inner diameter of 25 mm and a length of 900 mm. 10 g of molded catalyst-4 and 0.8 g of α-Al2O3 with a particle size of 0.9 ± 0.05 mm (which can pass through an 18-mesh sieve but not a 20-mesh sieve) are mixed evenly and packed into the catalyst bed of the reaction tube.

[0125] A feed gas consisting of methane and oxygen (volume ratio 4:1) was mixed and introduced at the top of the reaction tube. The reaction pressure was the pressure generated by the feed itself (0.020 MPa). The reaction temperature in the catalyst section was controlled at 810 °C, and the gas hourly space velocity (GHSV) was 12000 mL·g⁻¹. -1 ·h -1 .

[0126] Example 5

[0127] The method described in Example 1 was used, except that in step (a), the amount of starch used was 40 g, while the remaining steps and operations were the same as in Example 1. Molding catalyst-5 was obtained.

[0128] The methane oxidative coupling reaction was carried out using shaped catalyst-5, and the conditions and operations were the same as in Example 1.

[0129] Example 6

[0130] The method described in Example 1 was used, except that in step (b), the amount of water glass used was 40g, while the remaining steps and operations were the same as in Example 1. Molded catalyst-6 was obtained.

[0131] The methane oxidative coupling reaction was carried out using shaped catalyst-6, and the conditions and operations were the same as in Example 1.

[0132] Example 7

[0133] The methane oxidative coupling reaction was carried out using shaped catalyst-1 under the following conditions: the same catalytic reactor as in Example 1 was used, but only 10 g of shaped catalyst-1 was loaded, without α-Al₂O₃. All other conditions and operations were the same as in Example 1.

[0134] Example 8

[0135] The methane oxidative coupling reaction was carried out using shaped catalyst-1 under the following conditions: Using the same catalytic reactor as in Example 1, 10 g of shaped catalyst-1 was uniformly mixed with 1 g of α-Al₂O₃ with a particle size of 0.1 ± 0.05 mm (which can pass through a 120-mesh sieve but not a 170-mesh sieve) and packed into the catalyst bed of the reaction tube. All other conditions and operations were the same as in Example 1.

[0136] Example 9

[0137] The methane oxidative coupling reaction was carried out using shaped catalyst-1 under the following conditions: Using the same catalytic reactor as in Example 1, 10 g of shaped catalyst-1 was uniformly mixed with 1 g of α-Al₂O₃ with a particle size of 2 ± 0.05 mm (which can pass through an 8-mesh sieve but not a 12-mesh sieve) and packed into the catalyst bed of the reaction tube. All other conditions and operations were the same as in Example 1.

[0138] Example 10

[0139] The methane oxidative coupling reaction was carried out using shaped catalyst-1 under the following conditions: Using the same catalytic reactor as in Example 1, 10 g of shaped catalyst-1 was mixed with 3 g of α-Al₂O₃ with a particle size of 0.4 ± 0.05 mm (which can pass through a 35-mesh sieve but not a 50-mesh sieve) and uniformly packed into the catalyst bed of the reaction tube. All other conditions and operations were the same as in Example 1.

[0140] Example 11

[0141] The method described in Example 1 was used, except that the water glass used in step (a) had a specific gravity of 1.45 and a modulus of 2.8. All other conditions and operations were the same as in Example 1, and the shaped catalyst-7 was obtained.

[0142] The methane oxidative coupling reaction was carried out using shaped catalyst-7, and the conditions and operations were the same as in Example 1.

[0143] Example 12

[0144] The method described in Example 1 was used, except that manganese sulfate was used instead of manganese nitrate by an equal weight. All other conditions and operations were the same as in Example 1 to obtain shaped catalyst-8.

[0145] The methane oxidative coupling reaction was carried out using shaped catalyst-8, and the conditions and operations were the same as in Example 1.

[0146] Comparative Example 1

[0147] The method described in Example 1 was used, except that step (1) was omitted, and 100g of SiO2 was directly mixed with 14g of sodium tungstate, 10g of manganese nitrate, 10g of water glass, 10g of starch, and 175g of deionized water. All other steps and operations were the same as in Example 1. Molded catalyst-9 was obtained.

[0148] The methane oxidative coupling reaction was carried out using shaped catalyst-9, and the conditions and operations were the same as in Example 1.

[0149] Test Example 1

[0150] Ignoring trace impurities, the content of active components in the molded catalysts obtained in the above examples and comparative examples was calculated based on the amount of raw materials used. The mechanical strength of the molded catalysts obtained in the above examples and comparative examples was tested using a catalyst particle strength tester (50 particles were randomly selected for testing, and the average value was taken). Adsorption isotherm analysis was performed using a MICROMERITICS ASAP2020 fully automated adsorption analyzer, and the specific surface area of ​​the molded catalysts obtained in the above examples and comparative examples was calculated based on the isotherms. The results are detailed in Table 1. The content of the active component is defined as a percentage of the weight of SiO2 in the support.

[0151] Table 1

[0152]

[0153] *Catalyst-8 contains 3.39% by weight of S relative to the weight of SiO2 in the support.

[0154] Test Example 2

[0155] The components and contents of the reaction products collected from the above examples and comparative examples were analyzed using a gas chromatograph (Agilent 7890A). The methane conversion, C2 hydrocarbon selectivity, and CO content were calculated using the following formulas. XSelectivity and C2 hydrocarbon yield. Results are detailed in Table 2 (values ​​in the table are average values ​​over the steady-state reaction time).

[0156] Methane conversion rate = Amount of methane consumed in the reaction / Initial amount of methane × 100%

[0157] Ethylene selectivity = Amount of methane consumed to produce ethylene / Total methane consumption × 100%

[0158] Ethane selectivity = Amount of methane consumed to produce ethane / Total methane consumption × 100%

[0159] C2 hydrocarbon selectivity = ethane selectivity + ethylene selectivity

[0160] CO X (CO + CO2) selectivity = (Amount of methane consumed by the combined generation of CO and CO2) / (Total methane consumption) × 100%

[0161] C2 hydrocarbon yield = methane conversion rate × (ethane selectivity + ethylene selectivity)

[0162] Table 2

[0163]

[0164] The steady-state reaction time is determined by the catalyst’s reactivity (methane conversion and C2 hydrocarbon selectivity). When either the methane conversion or the C2 hydrocarbon selectivity continues to decrease (the decrease reaches or exceeds 5%), the reaction is stopped. The time between the start of the reaction and the stop of the reaction is the steady-state reaction time.

[0165] 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 method for preparing a catalyst for the direct oxidation of methane to C2 hydrocarbons, characterized in that, The method includes mixing and molding a cristobalite carrier, an active component precursor, a molding agent, and water to obtain a molded plastic body, and then subjecting the molded plastic body to a first drying and a first calcination in sequence to obtain the catalyst for the direct oxidation of methane to C2 hydrocarbons. The active component precursor includes a tungsten precursor and / or a manganese precursor; The molding agent is selected from binders, or extrusion aids and binders; The binder is selected from water glass with a specific gravity of 1.35-1.45 and a modulus of 1.5-2.

2. The method according to claim 1, wherein, The active component precursor is selected from at least one of sodium tungstate, potassium tungstate, ammonium tungstate, and manganese nitrate.

3. The method according to claim 1, wherein, The extrusion aid is selected from guar gum powder and / or starch.

4. The method according to claim 1, wherein, Compared to 100 parts by weight of the carrier based on SiO2, the amount of tungsten precursor used is 5-25 parts by weight; And / or, compared to 100 parts by weight of the carrier based on SiO2, the amount of manganese precursor is 5-30 parts by weight; And / or, the amount of molding agent is 5-45 parts by weight compared to 100 parts by weight of carrier based on SiO2. And / or, the total amount of water used is 120-180 parts by weight compared to 100 parts by weight of carrier based on SiO2.

5. The method according to claim 1, wherein, Compared to 100 parts by weight of the carrier based on SiO2, the amount of tungsten precursor used is 5-20 parts by weight. And / or, compared to 100 parts by weight of the carrier based on SiO2, the amount of manganese precursor is 5-28 parts by weight; And / or, the amount of extrusion aid used is 5-25 parts by weight compared to 100 parts by weight of carrier based on SiO2.

6. The method according to claim 1, wherein, Compared to 100 parts by weight of carrier based on SiO2, the amount of extrusion aid is 5-20 parts by weight. And / or, the amount of binder is 5-20 parts by weight compared to 100 parts by weight of carrier based on SiO2.

7. The method according to claim 1, wherein, Compared to 100 parts by weight of carrier based on SiO2, the amount of binder is 5-18 parts by weight.

8. The method according to claim 1, wherein, The molding method results in a molded plastic body with dimensions of 3-7 mm in diameter and 3-6 mm in length. And / or, the first drying method is selected from baking and / or vacuum drying; And / or, the first calcination method includes: heating to 750-900°C at a heating rate of 4-10°C / min, and then calcining at that temperature for 6-10 hours.

9. The method according to claim 8, wherein, The aspect ratio of the molded plastic body is 1:1-2.

10. The method according to claim 8, wherein, The first drying method is carried out in a step-by-step drying manner.

11. The method according to claim 10, wherein, The step-by-step drying method includes: (1) Low temperature drying: temperature 20-40℃, time 2-6h; (2) High temperature drying: temperature 100-160℃, time 4-10h.

12. The method according to claim 1, wherein, The method also includes the step of preparing a quartz support: mixing SiO2 and sodium salt and then subjecting it to a second drying and a second calcination.

13. The method according to claim 12, wherein, The average particle size of the SiO2 is 0.05-0.18 mm.

14. The method according to claim 12 or 13, wherein, The average particle size of the SiO2 is 0.08-0.15 mm.

15. The method according to claim 12, wherein, The sodium salt is selected from sodium nitrate and / or sodium tungstate.

16. The method according to claim 12, wherein, The weight ratio of SiO2 to sodium salt is 10-50:

1.

17. The method according to claim 12, wherein, The conditions for the second drying process include: a temperature of 80-150℃ and a time of 5-10 hours. And / or, the conditions for the second calcination include: heating to 800-900°C at a heating rate of 3-10°C / min, and then calcining at that temperature for 5-12 hours.

18. A molding catalyst for the direct oxidation of methane to C2 hydrocarbons, characterized in that, The catalyst is prepared according to the method described in any one of claims 1-17.

19. The molding catalyst according to claim 18, wherein, The catalyst comprises a quartz support and an active component supported on the quartz support, wherein the active component is selected from W, Mn and alkali metals; The catalyst has the following dimensions: diameter 3-7 mm, length 3-6 mm.

20. The molding catalyst according to claim 19, wherein, Based on the weight of SiO2 in the cristobalite support, the W content is 5-18.5% by weight. And / or, based on the weight of SiO2 in the cristobalite support, the Mn content is 1-10% by weight%. And / or, based on the weight of SiO2 in the cristobalite carrier, the alkali metal content is 0.5-5% by weight.

21. The molding catalyst according to claim 19, wherein, Based on the weight of SiO2 in the cristobalite support, the W content is 5.5-15% by weight. And / or, based on the weight of SiO2 in the cristobalite support, the Mn content is 1.5-9% by weight. And / or, based on the weight of SiO2 in the cristobalite carrier, the alkali metal content is 0.8-4% by weight.

22. The molding catalyst according to claim 18, wherein, The catalyst has an aspect ratio of 1:1-2.

23. A method for preparing C2 hydrocarbons, characterized in that, The method includes introducing a reaction gas containing CH4 and O2 into a reactor to carry out a methane oxidative coupling reaction; The reactor includes a reactor cavity made of quartz and a catalyst and packing material filled in the reactor cavity; Wherein, the catalyst is the catalyst according to any one of claims 18-22; the particle size of the filler does not exceed 1 / 3 of the catalyst size.

24. The method according to claim 23, wherein, The volume ratio of CH4 to O2 is 2-6:1; And / or, the conditions for the methane oxidative coupling reaction include: a reaction temperature of 750-850°C in the catalyst section and a gas hourly space velocity of 9000-15000 mL·g. -1 ·h -1 .

25. The method according to claim 23, wherein, The reaction time for the methane oxidative coupling reaction is 0.5-25 h.

26. The method of claim 25, wherein, The reaction time for the methane oxidative coupling reaction is 5-20 h.

27. The method according to claim 23, wherein, The reactor chamber has a length-to-diameter ratio of 15-40, and the ratio of the inner diameter of the reactor chamber to the size of the catalyst is 5-8:

1. And / or, the particle size of the filler is 1 / 10 to 1 / 3 of the size of the catalyst.

28. The method according to claim 23, wherein, The weight ratio of catalyst to packing material in the reactor cavity is 10-20:

1.

29. The method according to claim 23, wherein, The filler is selected from α-Al2O3 with a particle size not exceeding 1 mm.

30. The method according to claim 23, wherein, The filler is selected from α-Al2O3 with a particle size of 0.4-1 mm.

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