A catalyst for in-situ catalytic preparation of methanol from methane, its preparation method and application

Abstract

The present invention discloses a catalyst for in-situ catalytic preparation of methanol from methane, its preparation method and application, including the steps: Step 1, mixing a metal precursor solution with a carbon source or a nitrogen source, and carrying out a sealed hydrothermal synthesis reaction to obtain a MOF containing at least two valence state metals; Step 2, adding a reducing agent solution to a noble metal precursor solution, and carrying out a reduction reaction to obtain a noble metal nanoparticle solution; Step 3, dispersing the MOF obtained in Step 1 in the noble metal nanoparticle solution, and drying to remove the solvent to obtain the catalyst. In the present invention, noble metals are dispersed and loaded onto a metal-organic framework by a hydrothermal synthesis-liquid phase reduction deposition method, realizing the coupling process of in-situ synthesis, efficient decomposition of an oxidant and methane oxidation. A MOF material is formed by bridging carbon, nitrogen or oxygen with a transition metal in a mixed valence state. Applying it to the preparation of methanol from methane can not only reduce the reaction cost, but also obtain high methane catalytic activity and methanol selectivity.

Description

Technical Field

[0001] The present invention relates to the field of catalytic technology, and particularly relates to a catalyst for in-situ catalytic preparation of methanol from methane, a preparation method thereof, and an application thereof. Background Art

[0002] Methane is the main component of natural gas and is a cheap resource with huge reserves. However, directly burning it as a fuel or discharging it into the environment will lead to energy consumption and environmental problems. Therefore, upgrading methane to the oxygenated compound methanol with high added value is an effective way to achieve a sustainable chemical industry. Hydrogen peroxide, as an environmentally friendly oxidant, can activate methane to produce methanol under mild conditions. However, the industrial price of hydrogen peroxide is more expensive than methanol. Using H2 and O2 to in-situ produce hydrogen peroxide to oxidize methane is an effective way. Therefore, designing a high-performance catalyst for coupling in-situ hydrogen peroxide generation and hydrogen peroxide decomposition to activate methane is a hot spot and a difficult point in research.

[0003] Noble metals Au, Ag, and Pd are considered to be active metals for in-situ synthesis of hydrogen peroxide from H2 and O2. Smaller metal particle sizes (1-3 nm) and high metal particle dispersion are important factors for improving the hydrogen peroxide generation efficiency (Journal of Catalysis, 2017, 349, 30-40). In addition, transition metal organic framework materials containing mixed valence states can improve the efficiency of hydrogen peroxide decomposition through rapid redox cycling due to the presence of redox pairs (J. Am. Chem. Soc. 2018, 140, 12469-12475), and thus efficiently activate methane.

[0004] CN117299199A discloses a catalyst for methane oxidative conversion to methanol. The catalyst contains a molecular sieve support and an active metal element supported on the molecular sieve support, and the active metal is Au. The preparation process of this catalyst is simple, the preparation is highly repeatable, and the catalyst has high stability and can be reused multiple times. The invention also discloses a method for methane oxidative conversion to methanol, which uses carbon monoxide, oxygen, and water to in-situ generate hydrogen peroxide, and then reacts with methane to achieve one-step direct oxidation to methanol. Carbon monoxide is easy to obtain and has a low price, and its explosion limit range is narrower than that of hydrogen, improving the operation safety; and the route of the present invention has excellent methane conversion rate and methanol selectivity and has certain industrial application prospects.

[0005] Therefore, highly dispersing noble metal nanoparticles on an organic framework material with a transition metal redox pair to prepare a catalyst that can efficiently generate, decompose H2O2, and activate methane is the focus of the reaction research. Summary of the Invention

[0006] In view of the problems in the existing partial oxidation of methane to methanol, such as high cost of oxidants, low utilization efficiency of oxidants, and poor catalytic efficiency of catalysts, the present invention provides a preparation method of a catalyst for in-situ catalytic methane preparation of methanol. This catalyst can in-situ synthesize hydrogen peroxide as an oxidant and rapidly decompose hydrogen peroxide, thereby efficiently activating methane and having high catalytic activity.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A preparation method of a catalyst for in-situ catalytic methane preparation of methanol, comprising the steps:

[0009] Step 1, mixing a metal precursor solution with a carbon source or a nitrogen source, and performing a sealed hydrothermal synthesis reaction to obtain a MOF containing at least two valence state metals;

[0010] Step 2, adding a reducing agent solution to a noble metal precursor solution, and performing a reduction reaction to obtain a noble metal nanoparticle solution;

[0011] Step 3, dispersing the MOF obtained in Step 1 in the noble metal nanoparticle solution, and drying to remove the solvent to obtain the catalyst.

[0012] In the present invention, the noble metal is dispersed and loaded onto the metal-organic framework with a redox pair through a hydrothermal synthesis-liquid phase reduction deposition method, realizing the coupling process of in-situ synthesis, efficient decomposition of the oxidant, and methane oxidation. A MOF material is formed by bridging a mixed valence transition metal through carbon, nitrogen, or oxygen, and then the noble metal is loaded. This catalyst can in-situ synthesize hydrogen peroxide as an oxidant, and then the transition metal redox pair rapidly decomposes hydrogen peroxide, thereby efficiently activating methane. When this catalyst is applied to the preparation of methanol from methane, not only can the reaction cost be reduced, but also high methane catalytic activity and methanol selectivity can be obtained.

[0013] The metal precursor includes one or a combination of two or more of halide salts, nitrates, or other complex salts of iron, cobalt, or copper;

[0014] The carbon source includes benzoic acid and / or terephthalic acid; the nitrogen source includes one or a combination of two or more of urea, melamine, or dicyandiamide; the above nitrogen source and carbon source can both form a MOF in which a mixed valence transition metal is bridged through carbon, nitrogen, or oxygen.

[0015] The noble metal precursor includes one or a combination of two or more of halide salts, nitrates, or other complex salts of platinum, gold, or silver; further preferably, such as hexachloroplatinic acid, potassium chloroplatinate, palladium nitrate, palladium chloride, etc. and their hydrates.

[0016] The reducing agent includes one or a combination of two or more of ascorbic acid, sodium borohydride, hydrazine hydrate, sodium citrate, ethylene glycol, and ammonium formate. Sodium borohydride is preferred. It is relatively stable to water and oxygen in the air, easy to operate and process, and can also be widely applied to industrial scale.

[0017] In Step 1, the hydrothermal synthesis reaction temperature is 140 - 200 °C, and the reaction time is 4 - 24 h. Too high or too low temperature and time will affect the purity and crystallinity of the generated MOF. Preferably, the hydrothermal synthesis reaction temperature is 150 - 180 °C, and the reaction time is 10 - 20 h; more preferably, the hydrothermal synthesis reaction temperature is 170 - 180 °C, and the reaction time is 10 - 15 h;

[0018] In the MOF containing at least two valence state metals, the molar ratio of different valence state metals is 1:10 - 10:1. Preferably, the molar ratio of different valence state metals is 1:2 - 5:1, and more preferably 1:2 - 2:1.

[0019] Preferably, in the MOF, it is iron or copper with different valence states, such as Fe 3+ 、Fe 2+ 、Cu 2+ 。

[0020] In Step 1, the molar ratio of the metal precursor to the nitrogen source or carbon source is 1:5 - 5:1.

[0021] The mass ratio of the reducing agent to the noble metal precursor is 1 - 100:1. Too low mass ratio will cause the noble metal not to be completely reduced to nanoparticles, and too high will increase the size of the noble metal particles; the reduction reaction temperature is 0 - 60 °C, preferably 0 - 40 °C, more preferably 5 - 30 °C. Too high reduction temperature will increase the size of the noble metal particles and is not conducive to catalytic activity. The time is 5 - 30 min. Too long time will increase the size of the noble metal particles.

[0022] In Step 3, the mass of the noble metal in the noble metal nanoparticle solution is 0.5 - 3 wt% of the mass of the MOF. Preferably 0.5 - 1 wt%, reducing the noble metal loading is beneficial to reducing the catalyst preparation cost.

[0023] The present invention also provides the catalyst prepared by the described preparation method.

[0024] The present invention also provides the application of the described catalyst in the catalytic preparation of methanol from methane.

[0025] Preferably, in the reaction process of preparing methanol, the reaction temperature is: 25 - 90 °C; the reaction time is: 0.5 - 2 h; the oxygen pressure is: 0.3 - 0.8 MPa; the hydrogen pressure is: 0.8 - 1.5 MPa; the methane pressure is: 1.5 - 3 MPa; the mass ratio of the catalyst to the methane mass is: 1:5 - 1:50.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) By means of a simple hydrothermal synthesis-liquid phase reduction deposition method, the present invention disperses and loads noble metals onto a metal-organic framework having a redox pair, realizing the coupling process of in-situ synthesis, efficient decomposition of an oxidant, and methane oxidation. The catalyst exhibits excellent catalytic performance in the reaction of partial oxidation of methane to methanol.

[0028] (2) Through a simple catalyst preparation process, the present invention couples the two processes of in-situ generation of an oxidant and methane oxidation, reducing the reaction cost, facilitating the industrial promotion of the catalyst, and having a simple and easy-to-operate catalyst preparation process, simple and easily available raw materials, and potential for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 XRD patterns of the Fe 3+ -Fe 2+ -MOF material and the prepared Pd / Fe 3+ -Fe 2+ -MOF catalyst in Example 2.

[0030] Figure 2 TEM image of the prepared Pd / Fe 3+ -Fe 2+ -MOF catalyst in Example 2.

[0031] Figure 3 XPS spectrum of Pd in the prepared Pd / Fe 3+ -Fe 2+ -MOF catalyst in Example 2.

[0032] Figure 4 Mössbauer spectrum of Fe in the prepared Pd / Fe 3+ -Fe 2+ -MOF catalyst in Example 2.

[0033] Figure 5 Performance evaluation diagrams of the reaction of partial oxidation of methane to methanol in Examples 1-4 and Comparative Examples 1-3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Those skilled in the art, on the basis of understanding the technical solutions of the present invention, make modifications or equivalent replacements without departing from the spirit and scope of the technical solutions of the present invention, which should all be covered within the protection scope of the present invention.

[0035] The raw materials used in the following specific embodiments are all purchased from the market.

[0036] Example 1 Fe 3+ -Fe 2+ -MOF supported 1 wt% Pd catalyst

[0037] (1) Disperse 2 mol of ferric chloride in 20 mL of formamide, then add 2 g of dicyandiamide to the above solution to form a mixed solution. Transfer the mixed solution to a hydrothermal reactor and hydrothermally react at 150 °C for 18 h to obtain Fe 3+ -Fe 2+ -MOF material; after ferric chloride and dicyandiamide are put into the hydrothermal reactor and react therein, a MOF structure mixed with Fe connected by cyanide groups will be formed through crystal nucleation and growth. There is a redox balance between divalent iron and trivalent iron to maintain the structural stability. Under this synthesis condition, Fe 2+ and Fe 3+ is obtained, and the molar ratio of Fe 3+ :Fe 2+ is 4:1.

[0038] (2) Prepare a 40 mL solution of 2.5 mg of the noble metal precursor Pd(NO3)2·2H2O. Prepare a fresh NaBH4 solution with the mass ratio of the reducing agent NaBH4 to the noble metal precursor being 28:1 and slowly add it dropwise thereto at one time. Continue to stir at room temperature for 0.5 h to obtain a solution containing Pd nanoparticles;

[0039] (3) Add 100 mg of Fe 3+ -Fe 2+ -MOF material to the above solution of Pd nanoparticles. The mass of Pd metal is 1 wt% of the MOF material. Continue to stir for 0.5 h, and then dry the solution in a rotary evaporator to obtain the catalyst of Pd supported on Fe 3+ -Fe 2+ -MOF, denoted as Pd / Fe 3+ -Fe 2+ -MOF.

[0040] Example 2 Fe 3+ -Fe 2+ -MOF supported 1 wt% Pd catalyst

[0041] (1) Disperse 2 mol of ferric chloride in 20 mL of formamide, then add 2 g of dicyandiamide to the above solution to form a mixed solution. Transfer the mixed solution to a hydrothermal reactor and hydrothermally react at 180 °C for 12 h to obtain Fe 3+ -Fe 2+ -MOF material; after verification, it is not theoretically Fe2+ The more, the better. Among the experimental conditions explored so far, Fe is obtained by hydrothermal treatment at 180 °C for 12 h 3 + :Fe 2+ The molar ratio of 1:2 is the best. Because the Fenton reaction (H2O2 decomposition) requires Fe 3+ , Fe 2+ to participate simultaneously, thus continuously forming a reaction cycle.

[0042] Fe 2+ + H2O2 → Fe 3+ + OH - + ·OH

[0043] Fe 3+ + H2O2 → Fe 2+ + H + + ·OH

[0044] (2) Prepare a 40 mL solution of 2.5 mg of the noble metal precursor Pd(NO3)2·2H2O. Prepare a fresh NaBH4 solution with a mass ratio of the reducing agent NaBH4 to the noble metal precursor of 28:1 and slowly add it dropwise all at once. Continue stirring at room temperature for 0.5 h to obtain a solution containing Pd nanoparticles;

[0045] (3) Add 100 mg of the Fe 3+ -Fe 2+ -MOF material to the above solution of Pd nanoparticles. The mass of Pd metal is 1 wt% of the MOF material. Continue stirring for 0.5 h, and then dry the solution in a rotary evaporator to obtain a catalyst of Pd loaded on the Fe 3+ -Fe 2+ -MOF material, denoted as Pd / Fe 3+ -Fe 2+ -MOF.

[0046] The main difference from Example 1 is the different synthesis temperature and time. At a higher temperature, the oxidation rate of Fe 2+ may increase, and a shorter reaction time may result in the ratio of Fe 2+ and Fe 3+ not reaching equilibrium, while a longer reaction time may increase the ratio of Fe 2+ oxidized to Fe 3+ . The best synthesis conditions were screened out by optimizing the synthesis conditions, and Example 2 was obtained.

[0047] Figure 1 For the Fe 3+ -Fe 2+ -MOF material and the prepared Pd / Fe 3+ -Fe2+ - XRD pattern of the MOF catalyst. It can be seen that the MOF material was successfully synthesized. In addition, there are no diffraction peaks of Pd nanoparticles, indicating that the Pd nanoparticles have a small particle size and high dispersion.

[0048] Figure 2 For the Pd / Fe prepared in Example 2 3+ -Fe 2+ - TEM image of the MOF catalyst. It can be seen that Pd nanoparticles are effectively loaded on the MOF material.

[0049] Figure 3 For the Pd / Fe prepared in Example 2 3+ -Fe 2+ - XPS spectrum of Pd in the MOF catalyst. It can be seen that the Pd nanoparticles are in the 0 valence state.

[0050] Figure 4 For the Pd / Fe prepared in Example 2 3+ -Fe 2+ - Mössbauer spectrum of Fe in the MOF catalyst. It can be seen that the 3+ and Fe 2+ molar ratio is 1:2.

[0051] Example 3 Fe 3+ -Cu 2+ - MOF-supported 1 wt% Pd catalyst

[0052] (1) Disperse 1 mol of ferric chloride and 1 mol of copper chloride in 20 mL of deionized water. Then add 2 g of dicyandiamide to the above solution to form a mixed solution. Transfer the mixed solution to a hydrothermal autoclave and hydrothermal react at 180 °C for 12 h to obtain the Fe 3+ -Cu 2+ - MOF material; the actual molar ratio of iron and copper ions in the product is 1:1, which is consistent with the molar ratio of the input raw materials ferric chloride and copper chloride.

[0053] (2) Prepare a 40 mL solution of 2.5 mg of the noble metal precursor Pd(NO3)2·2H2O. Prepare a fresh NaBH4 solution with a mass ratio of the reducing agent NaBH4 to the noble metal precursor of 28:1 and slowly add it dropwise all at once. Continue to stir at room temperature for 0.5 h to obtain a solution containing Pd nanoparticles;

[0054] (3) Add 100 mg of the Fe 3+ -Cu 2+ - MOF material to the above solution of Pd nanoparticles. The mass of Pd metal is 1 wt% of the MOF material. Continue to stir for 0.5 h, and then dry the solution in a rotary evaporator to obtain the Fe 3+ -Cu 2+- Pd catalyst supported on MOF material, denoted as Pd / Fe 3+ - Cu 2+ - MOF.

[0055] Example 4 Fe 3+ - Fe 2+ - 1 wt% Au catalyst supported on MOF

[0056] (1) Disperse 2 mol of ferric chloride in 20 mL of formamide, then add 2 g of urea to the above solution to form a mixed solution. Transfer the mixed solution to a hydrothermal autoclave and hydrothermally react at 180 °C for 12 h to obtain Fe 3+ - Fe 2+ - MOF material;

[0057] (2) Prepare a 40 mL solution of 1.5 mg of the noble metal precursor AuCl3, and prepare a fresh NaBH4 solution with a mass ratio of the reducing agent NaBH4 to the noble metal precursor of 28:1 and slowly add it dropwise all at once. Continue to stir at room temperature for 0.5 h to obtain a solution containing Au nanoparticles;

[0058] (3) Add 100 mg of Fe 3+ - Fe 2+ - MOF material to the above Au solution. The mass of Au metal is 1 wt% of the MOF material. Continue to stir for 0.5 h, and then dry the solution in a rotary evaporator to obtain Fe 3+ - Fe 2+ - Au catalyst supported on MOF material, denoted as Au / Fe 3+ - Fe 2+ - MOF.

[0059] Comparative Example 1 Fe supported on PCN 3+ Catalyst

[0060] (1) Dissolve 3 mg of ferric chloride in water, add 97 mg of PCN (polymeric carbon nitride) support to the ferric chloride solution, and stir for 0.5 h;

[0061] (2) Dry the above solution in a rotary evaporator, grind the obtained solid, and calcine it in a muffle furnace at 500 °C for 5 h to obtain the Fe2O3 / PCN catalyst.

[0062] Comparative Example 2 Pd catalyst supported on PCN

[0063] (1) Prepare a 40 mL solution of 2.5 mg of the noble metal precursor Pd(NO3)2·2H2O, and prepare a fresh NaBH4 solution with a mass ratio of the reducing agent NaBH4 to the noble metal precursor of 28:1 and slowly add it dropwise all at once. Continue to stir at room temperature for 0.5 h to obtain a solution containing Pd nanoparticles;

[0064] (2) Add 100 mg of the PCN support to the above Pd solution, and continue stirring for 0.5 h. The mass of Pd metal is 1 wt% of the PCN material. Subsequently, dry the solution in a rotary evaporator to obtain the Pd-loaded catalyst on the PCN material, denoted as Pd / PCN.

[0065] Comparative Example 3 Fe 3+ -MOF-supported 1 wt% Pd catalyst

[0066] (1) Disperse 2 mol of ferric chloride in 20 mL of deionized water. Subsequently, add 2 g of terephthalic acid to the above solution to form a mixed solution. Transfer the mixed solution to a hydrothermal autoclave and hydrothermally react at 150 °C for 18 h to obtain Fe 3+ -MOF material;

[0067] (2) Prepare a 40 mL solution of 2.5 mg of the noble metal precursor Pd(NO3)2·2H2O. Prepare a fresh NaBH4 solution with a mass ratio of reducing agent NaBH4 to noble metal precursor of 28:1 and slowly add it dropwise all at once. Continue stirring at room temperature for 0.5 h to obtain a solution containing Pd nanoparticles;

[0068] (3) Add 100 mg of Fe 3+ -MOF material to the above Pd nanoparticle solution. The mass of Pd metal is 1 wt% of the MOF material. Continue stirring for 0.5 h. Subsequently, dry the solution in a rotary evaporator to obtain the Pd-loaded catalyst on the Fe 3+ -MOF material, denoted as Pd / Fe 3+ -MOF.

[0069] Performance evaluation of the catalyst

[0070] Perform the performance evaluation of the catalysts prepared in the examples and comparative examples for the partial oxidation of methane to methanol. The reaction is carried out in a high-pressure autoclave reactor.

[0071] Application Example 1

[0072] Step 1, Weigh 10 mg of the catalysts of Examples 1-4 and Comparative Examples 1-3, fill them in the quartz liner of the autoclave reactor, and then add 40 mL of water to the liner and tighten the autoclave reactor;

[0073] Step 2, Subsequently, introduce O2 to displace the air in the reactor, introduce 0.3 MPa - O2, 0.8 MPa - H2, and 1.5 MPa - CH4, set the reaction temperature to 50 °C, and the reaction time to 0.5 h.

[0074] Step 3: After the reaction is completed, place the reaction kettle in an ice-water bath. After the reaction temperature drops to room temperature, centrifuge the reacted liquid, take the supernatant for liquid nuclear magnetic analysis, and calculate the product yield and methanol selectivity by the external standard method. Table 1 and Figure 5 are the comparative data of the reaction performance of partial oxidation of methane to methanol for Examples 1-4 and Comparative Examples 1-3.

[0075] Table 1 Performance evaluation results of catalytic partial oxidation of methane to methanol for Examples 1-4 and Comparative Examples 1-3

[0076]

[0077] From Figure 5 and Table 1, it can be seen that the performance is optimal when the molar ratio of Fe 3+ and Fe 2+ is 1:2. The reason for the performance improvement of Example 2 compared with Example 1 is that by optimizing the synthesis conditions of the catalyst, the optimal molar ratio of Fe 3+ and Fe 2+ is formed. The redox pair between Fe 3+ and Fe 2+ cycles continuously, improving the efficiency of H2O2 decomposition into ·OH, thereby enhancing the activation of methane and promoting the formation of methanol. The performance of Example 3 is average because the coupling of Fe with other metals is not as efficient as the redox pair of Fe 3+ and Fe 2+ in decomposing H2O2. The performance of Example 4 is average because Au, as the active metal for in-situ synthesis of H2O2 from H2 and O2, produces less H2O2 than Pd. However, overall, they are far better than Comparative Examples 1-3.

Claims

1. A method for preparing a catalyst for catalyzing the preparation of methanol from methane, characterized in that, Including the steps: Step 1: Mix a metal precursor solution with a carbon source or a nitrogen source, and seal for a hydrothermal synthesis reaction at 140 - 200 °C for 4 - 24 h to obtain a MOF containing at least two-valence-state metals; Step 2: Add a reducing agent solution to a noble metal precursor solution, and obtain a noble metal nanoparticle solution through a reduction reaction; Step 3: Disperse the MOF obtained in Step 1 in the noble metal nanoparticle solution, and dry to remove the solvent to obtain the catalyst; The metal precursor includes one or a combination of two or more of halide salts, nitrates, or other complex salts of iron, cobalt, or copper; The carbon source includes benzoic acid and / or terephthalic acid; The nitrogen source includes one or a combination of two or more of urea, melamine, or dicyandiamide; The noble metal precursor includes one or a combination of two or more of halide salts, nitrates, or other complex salts of platinum, gold, or silver.

2. The preparation method of the catalyst for catalytically preparing methanol from methane according to claim 1, wherein The reducing agent includes one or a combination of two or more of ascorbic acid, sodium borohydride, hydrazine hydrate, sodium citrate, ethylene glycol, ammonium formate.

3. The preparation method of the catalyst for catalytically preparing methanol from methane according to claim 1, characterized in that, In the MOF containing at least two-valence-state metals, the molar ratio of different-valence-state metals is 1:10 - 10:

1.

4. The preparation method of the catalyst for catalytically preparing methanol from methane according to claim 1, characterized in that, In Step 1, the molar ratio of the metal precursor to the nitrogen source or the carbon source is 1:5 - 5:

1.

5. The preparation method of the catalyst for catalytically preparing methanol from methane according to claim 1, characterized in that, The mass ratio of the reducing agent to the noble metal precursor is 1 - 100:1; the reduction reaction temperature is 0 - 60 °C, and the time is 5 - 30 min.

6. The preparation method of the catalyst for catalytically preparing methanol from methane according to claim 1, characterized in that, In Step 3, the mass of the noble metal in the noble metal nanoparticle solution is 0.5 - 3 wt% of the mass of the MOF.

7. The catalyst prepared by the preparation method according to any one of claims 1 - 6.

8. The application of the catalyst according to claim 7 in catalytically preparing methanol from methane.

9. The application according to claim 8, wherein During the reaction process of preparing methanol, the reaction temperature is: 25 - 90 °C; the reaction time is: 0.5 - 2 h; the oxygen pressure is: 0.3 - 0.8 MPa; the hydrogen pressure is: 0.8 - 1.5 MPa; the methane pressure is: 1.5 - 3 MPa; the mass ratio of the catalyst to the methane is: 1:5 - 1:50.

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