A method for the production of acetic acid by low-temperature oxidation carbonylation of methane
The oxidative carbonylation of methane to acetic acid using the IrCu/ND@G catalyst at low temperatures solves the problems of high energy consumption and easy catalyst deactivation, achieving efficient acetic acid production and showing good prospects for industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-11-29
- Publication Date
- 2026-05-29
AI Technical Summary
The existing technology for converting methane to acetic acid has problems such as high energy consumption, easy catalyst deactivation, and low selectivity. In particular, when methane is used directly for acetic acid synthesis, the energy utilization efficiency is low and the catalyst is difficult to reuse.
Using an IrCu/ND@G catalyst, Ir and Cu bimetallic atoms were prepared on a graphene-coated nanodiamond support via an impregnation method. Acetic acid was then prepared by a low-temperature oxidative carbonylation reaction in which CH4, CO, and O2 reacted in an aqueous solvent at a temperature of 120-200℃ and a pressure of 2-5 MPa.
At 150 °C, the acetic acid yield reached 230.32 mmol/g metal, and the selectivity of the carbon-containing product in the liquid phase reached 100%. The reaction conditions were mild, and the acetic acid yield and selectivity were high.
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Figure CN122102883A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of chemistry and chemical engineering, and more particularly to a method for producing acetic acid by low-temperature oxidative carbonylation of methane. Background Technology
[0002] Methane, as a promising green energy source, is one of the raw materials for synthesizing high-value-added chemicals such as methanol and acetic acid. From a chemical synthesis perspective, methane can be directly activated to convert into oxygen-containing products. However, the high dissociation energy of the first CH bond in methane makes this goal difficult, while activating subsequent CH bonds is relatively easy. This makes selectively activating methane without over-oxidation a challenge. In industry, methane is typically converted under high temperature and pressure, with the main processes including methane steam or drying reforming, partial oxidation, and oxidative coupling. However, these processes inevitably come with some side effects, one being catalyst deactivation due to coke formation, and the other being low overall efficiency due to the large energy input.
[0003] Acetic acid is a crucial intermediate in the chemical industry, with a global demand of 650 metric tons per year. The current industrial synthesis of acetic acid utilizes the Cativa process, which employs carbon monoxide and hydrogen produced from methane decomposition—a steam reforming (SMR) process. Methanol synthesized using this method is used as a precursor, and [Ir(CO)₂I₂]⁻ is used as a catalyst to accelerate the carbonylation of methanol, yielding a large quantity of acetic acid. However, in this process, methane is not directly used for acetic acid synthesis, resulting in low energy efficiency. Secondly, there is the issue of catalyst lifespan. Ir, as a scarce and precious metal, is difficult to reuse due to the homogeneity of the catalyst.
[0004] Thermal catalysis can be considered a potential method for the conversion of methane to acetic acid. Previous studies have shown that the thermal conversion of methane requires an application temperature above 80 °C to achieve methane oxidation (Z. Liang, T. Li, M. Kim, A. Asthagiri and J. F. Low-temperature activation of methane on the IrO2(110) surface. Weaver Science, 2017, 356(6335):299-303). However, this process suffers from high energy consumption and low product selectivity, resulting in low efficiency. Therefore, developing a new, highly efficient thermal catalytic method for methane is crucial. Summary of the Invention
[0005] The present invention aims to provide a method for the low-temperature oxidative carbonylation of methane to produce acetic acid, which exhibits high CH3COOH yield and selectivity, and at a low reaction temperature.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows:
[0007] This invention provides a method for producing acetic acid by low-temperature oxidative carbonylation of methane. Water is used as a solvent, and a mixture of CH4, CO, O2, and Ar gases is introduced into a reaction apparatus. Under the action of a catalyst, CH4, CO, and O2 react to produce acetic acid. The catalyst has the chemical formula IrCu / ND@G and is composed of an active component and a carbon support. The active component consists of Ir and Cu, both of which are atomically dispersed on the surface of the carbon support, which is graphene-coated nanodiamond.
[0008] Furthermore, in the above technical solution, the catalyst is prepared by an impregnation method, and the preparation method specifically includes the following steps:
[0009] (1) The nanodiamond raw material is treated in an inert atmosphere at 900-1100℃ for 3-8 hours to obtain nanodiamond / graphene carrier.
[0010] (2) Add chloroiridic acid solution and cuprous chloride solution to the solvent, add the graphene-coated nanodiamond carrier obtained in step (1) and disperse it evenly. Stir for 12-24 hours under open conditions, then keep it warm under vacuum for 10-24 hours at a temperature of 60-150℃. After cooling to room temperature, the catalyst precursor is obtained.
[0011] (3) The catalyst precursor obtained in step (2) is treated in a mixed atmosphere of oxygen and inert gas at 200-400℃ for 1-3h to obtain IrCu / ND@G.
[0012] Furthermore, in the above technical solution, the reaction pressure is 2-5 MPa.
[0013] Furthermore, in the above technical solution, the volume percentage of CH4 is 10-23.3%, the volume percentage of CO is 30-43.3%, and the balance is a mixture of O2 and Ar. The total volume percentage of CH4, CO, and the mixture of O2 and Ar is 100%, preferably 16.7% CH4, 36.6% CO, and 46.7% O2 and Ar mixture.
[0014] Furthermore, in the above technical solution, the volume percentage of oxygen in the O2 and Ar mixture is 7%.
[0015] Furthermore, in the above technical solution, the reaction temperature is 120-200℃, the reaction time is 1-15h, preferably the reaction temperature is 150-180℃, and most preferably the reaction temperature is 150℃ and the reaction time is 10h.
[0016] Furthermore, in the above technical solution, the reaction device is a high-pressure reaction vessel.
[0017] Furthermore, in the above technical solution, the reaction is carried out under stirring at a speed of 200-1000 r / min, preferably 550 r / min.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0019] (1) Under the action of the reaction catalyst of this invention, Ir and Cu bimetallic atoms are used as active sites for the reaction, and defect-rich graphene-encapsulated nanodiamonds are used as supports. The defect sites on the graphene can effectively confine the IrCu biatoms, enabling oxygen and carbon monoxide to convert methane into acetic acid and methanol in one step through two independent pathways. The acetic acid yield reaches 230.32 mmol / g. metal At 150℃, the selectivity of carbon-containing products in the liquid phase reaches 100%.
[0020] (2) The reaction conditions of this invention are mild, exhibiting high acetic acid yield and selectivity, and have good prospects for industrial application. Attached Figure Description
[0021] Figure 1 HAADF-STEM image of 0.2IrCu / ND@G;
[0022] Figure 2 The reaction performance was evaluated for different CH4 contents.
[0023] Figure 3 The reaction performance was evaluated for different CO contents.
[0024] Figure 4 The reaction performance at different reaction temperatures;
[0025] Figure 5 The reactivity of different carbon supports. Detailed Implementation
[0026] The catalyst for the low-temperature oxidative carbonylation of methane to acetic acid and its preparation method provided by the present invention are described in further detail below. However, the scope of the claims of the present invention is not limited to these embodiments. At the same time, the embodiments only provide some conditions for achieving this purpose, but do not mean that these conditions must be met to achieve this purpose.
[0027] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.
[0028] The preparation method of the IrCu / ND@G catalyst in the following examples is as follows:
[0029] Step 1: Treat the nanodiamond raw material at 1100℃ for 4 hours in an inert atmosphere to obtain nanodiamond / graphene (ND@G) carrier;
[0030] Step 2: Add 5 ml of ethanol to a 25 ml beaker. Calculate the amount of chloroiridium acid solution needed based on an Ir loading of 0.2 wt% and weigh it into the beaker. Calculate the amount of cuprous chloride solution needed based on a Cu loading of 0.4 wt% and weigh it into the beaker. Place the ND@G support into the beaker and sonicate for 2 min to disperse it evenly. Stir with a magnetic stirrer under open conditions for 24 h. Then keep it at a vacuum temperature of 60 °C for 24 h. After cooling to room temperature, the catalyst precursor is obtained.
[0031] (3) The catalyst precursor was treated at 300°C for 1.5 h in a mixed atmosphere of oxygen and helium with an oxygen volume fraction of 20% to obtain the IrCu bimetallic atom catalyst, denoted as 0.2IrCu / ND@G.
[0032] The IrCu / ND, IrCu@G, and IrCu / CNTs catalysts were prepared using the same method as described above, except that nanodiamond, graphene (Aladdin G302114), and carbon nanotubes (Aladdin C121257) were used as supports to prepare 0.2IrCu / ND, 0.2IrCu@G, and 0.2IrCu / CNTs, respectively. The loading of Ir was 0.2wt% and the loading of Cu was 0.4wt% in all cases.
[0033] Example 1
[0034] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 36.6% CO, 46.7% O₂, and Ar by volume percentage was introduced, maintaining a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 150 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 2 middle.
[0035] Example 2
[0036] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, the reactor was introduced with 10% CH₄, 36.6% CO, and 53.4% O₂ and Ar by volume, respectively. The total pressure was 3 MPa, the heating rate was 60 °C / min, and the temperature was raised to 150 °C and maintained for 10 h with stirring at 550 rpm. The products were analyzed by NMR and chromatography. Specific reaction performance details are listed below. Figure 2 middle.
[0037] Example 3
[0038] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, the reactor was purged with a mixture of 23.3% CH₄, 36.6% CO, and 40.1% O₂ and Ar by volume, respectively. The total pressure was 3 MPa, the heating rate was 60 °C / min, the temperature was raised to 150 °C, and maintained for 10 h with stirring at 550 rpm. The products were analyzed by NMR and chromatography. Specific reaction performance details are listed below. Figure 2 middle.
[0039] Example 4
[0040] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, the reactor was introduced with a mixture of 16.7% CH₄, 30% CO, and 53.3% O₂ and Ar by volume, respectively. The total pressure was 3 MPa, the heating rate was 60 °C / min, the temperature was raised to 150 °C, and maintained for 10 h with stirring at 550 rpm. The products were analyzed by NMR and chromatography. Specific reaction performance details are listed below. Figure 3 middle.
[0041] Example 5
[0042] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, the reactor was introduced with 16.7% CH₄, 43.3% CO, and 40% O₂ and Ar by volume, respectively. The total pressure was 3 MPa, the heating rate was 60 °C / min, and the temperature was raised to 150 °C and maintained for 10 h with stirring at 550 rpm. The products were analyzed by NMR and chromatography. Specific reaction performance details are listed below. Figure 3 middle.
[0043] Example 6
[0044] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 50% CO, 33.3% O₂, and Ar by volume fraction was introduced. The total pressure was 3 MPa, and the heating rate was 60 °C / min. The temperature was raised to 150 °C and held for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 3 middle.
[0045] Example 7
[0046] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 36.6% CO, 46.7% O₂, and Ar by volume percentage was introduced, maintaining a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 120 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 4 middle.
[0047] Example 8
[0048] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 36.6% CO, 46.7% O₂, and Ar by volume percentage was introduced, maintaining a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 180 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 4 middle.
[0049] Example 9
[0050] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). A mixture of CH₄, CO, and O₂ and Ar gases (O₂ 7% by volume, Ar as the equilibrium gas) was introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 36.6% CO, 46.7% O₂ and Ar gases (by volume percentage) was introduced, with a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 200 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 4 middle.
[0051] Comparative Example 1
[0052] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, the reactor was introduced with 3.3% CH₄ and 36.7% CO, and 60% O₂ and Ar by volume, respectively. The total pressure was 3 MPa, the heating rate was 60 °C / min, and the temperature was raised to 150 °C and maintained for 10 h with stirring at 550 rpm. The products were analyzed by NMR and chromatography. Specific reaction performance details are listed below. Figure 2 middle.
[0053] Comparative Example 2
[0054] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). A mixture of CH₄, CO, and O₂ and Ar gases (O₂ 7% by volume, Ar as the equilibrium gas) was introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 30% CH₄, 36.7% CO, and 33.3% O₂ and Ar gases (by volume percentage) was introduced, maintaining a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 150 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 2 middle.
[0055] Comparative Example 3
[0056] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). A mixture of CH₄, CO, and O₂ and Ar gases (7% O₂ by volume, Ar as the equilibrium gas) was introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 23.3% CO, 60% O₂, and Ar by volume was introduced, with a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 150 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 3 middle.
[0057] Comparative Example 4
[0058] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / ND catalyst (Ir 0.2 wt%, Cu 0.4 wt%). A mixture of CH₄, CO, O₂, and Ar (7% O₂ by volume, Ar as the equilibrium gas) was introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 46.7% CO, and 36.6% O₂ and Ar was introduced, maintaining a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 150 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 5 middle.
[0059] Comparative Example 5
[0060] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu / CNTs catalyst (Ir 0.2 wt%, Cu 0.4 wt%). CH₄, CO, and a mixture of O₂ and Ar (7% O₂ by volume, Ar as the equilibrium gas) were introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 36.6% CO, 46.7% O₂, and Ar was introduced, maintaining a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 150 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 5 middle.
[0061] Comparative Example 6
[0062] A high-pressure reactor apparatus was used, comprising a reactor body, a reactor lid, and a reactor liner. The lid was fitted with a gas delivery pipe and a thermocouple sheath. 10 ml of H₂O was added as the reaction solution, along with 15 mg of IrCu@G catalyst (Ir 0.2 wt%, Cu 0.4 wt%). A mixture of CH₄, CO, O₂, and Ar (7% O₂ by volume, Ar as the equilibrium gas) was introduced into the high-pressure reactor. The system was first purged three times with the O₂ and Ar mixture to remove air. Subsequently, a mixture of 16.7% CH₄, 36.7% CO, and 46.6% O₂ and Ar was introduced, maintaining a total pressure of 3 MPa. The heating rate was 60 °C / min, reaching 150 °C and holding for 10 h with stirring at 550 rpm. The products were analyzed using NMR and chromatographic methods. Specific reaction performance details are listed below. Figure 5 middle.
[0063] The above examples are for reference only. Any technical solutions that are similar to or derived from the concept of this patent are within the scope of protection of this invention.
Claims
1. A method for producing acetic acid by low-temperature oxidative carbonylation of methane, characterized in that: Using water as a solvent, CH4, CO, and a mixture of O2 and Ar are introduced into the reaction apparatus, and acetic acid is prepared by reacting CH4, CO and O2 under the action of a catalyst. The catalyst has the chemical formula IrCu / ND@G and is composed of an active component and a carbon support. The active component is Ir and Cu, both of which are atomically dispersed on the surface of the carbon support, which is graphene-coated nanodiamond.
2. The method according to claim 1, characterized in that: The reaction pressure is 2-5 MPa.
3. The method according to claim 1, characterized in that: The volume percentage of CH4 is 10-23.3%, the volume percentage of CO is 30-43.3%, and the balance is a mixture of O2 and Ar. The total volume percentage of CH4, CO, and the mixture of O2 and Ar is 100%.
4. The method according to claim 1, characterized in that: The volume percentage of oxygen in the O2 and Ar mixture is 7%.
5. The method according to claim 1, characterized in that: The reaction temperature is 120-200℃, and the reaction time is 1-15h.
6. The method according to claim 1, characterized in that: The reaction temperature is 150-180℃.
7. The method according to claim 1, characterized in that: The reaction device is a high-pressure reactor.