Method for producing hydrocarbon compound

Abstract

Provided is a method for producing a hydrocarbon compound, which is characterized in that carbon dioxide and methane are irradiated with plasma in the presence of a solid catalyst wherein two or more metals are supported by a carrier. The method makes it possible to produce various hydrocarbon compounds with a high conversion rate of methane or carbon dioxide by using an inexpensive catalyst having a long life when producing a hydrocarbon compound by utilizing a technique of methane dry reforming that utilizes plasma.

Description

Process for producing hydrocarbon compounds

[0001] The present invention relates to a process for producing hydrocarbon compounds from carbon dioxide and methane by dry reforming methane technology.

[0002] In recent years, against the background of carbon dioxide emission regulations from the perspective of carbon neutrality, initiatives (CCS) for separating and recovering carbon dioxide in exhaust gas and burying it underground have been progressing. However, there are problems that there are few suitable sites for burying carbon dioxide, and the cost of transporting and storing carbon dioxide overseas is extremely high (Non-Patent Document 1).

[0003] Therefore, means for effectively utilizing the recovered CO ２ is required. As methods for producing such chemical products, there are known reverse water gas shift reaction (H ２ +CO ２ →H ２ O+CO) using a catalyst and endotherm, and dry reforming of methane (DRM) (CH ４ +CO ２ →2H ２ +2CO) using a catalyst and plasma.

[0004] Generally, dry reforming of methane produces carbon monoxide and hydrogen as described above, but hydrocarbons can also be produced by changing the reaction conditions.

[0005] As a technology for producing such hydrocarbons, dry reforming methane technology using plasma is known, for example, a technology using cobalt-supported silica (Non-Patent Document 2) and a technology using a noble metal-supported alumina catalyst (Non-Patent Document 3) are known.

[0006] However, in the technology of Non-Patent Document 2, when CH ４ / CO ２ =2, the conversion rates are 45% / 33%, and large amounts of alcohols and CO are produced, so the yield of the target hydrocarbon is low, and there is no description of catalyst life. Further, in the technology of Non-Patent Document 3, when CH ４ / CO ２ =1, a conversion rate of 33% / 22% is achieved, and C1-C5 hydrocarbons are produced, but with an inexpensive Cu-supported alumina catalyst, CO ２The conversion rate is low and needs to be improved, and there are also issues with catalyst costs.

[0007] Ministry of Economy, Trade and Industry website (CCS Project Cost and Implementation Scheme Study Working Group, 3rd CCS Project Cost and Implementation Scheme Study Working Group Meeting (held October 31, 2022), Document 3 (https: / / www.meti.go.jp / shingikai / energy_environment / ccs_choki_roadmap / jisshi_kento / pdf / 003_04_00.pdf)) Appl. Catal. B, 2020, 261, 118228.chem. Eng. J., 2020, 397, 125519.

[0008] Therefore, the present invention aims to provide a technology for producing hydrocarbon compounds using plasma-based dry reforming methane technology that is inexpensive, less prone to performance degradation, has a high conversion rate of methane or carbon dioxide, and can produce various hydrocarbon compounds, with the aim of commercializing such technology.

[0009] As a result of diligent research to solve the above problems, the inventors of this invention have found that the above problems can be improved by irradiating a solid catalyst in which two or more types of metals are supported on a carrier with plasma.

[0010] In other words, the present invention is as follows: [1] A method for producing a hydrocarbon compound, characterized by irradiating carbon dioxide and methane with plasma in the presence of a solid catalyst on which two or more metals are supported on a carrier. [2] The method for producing a hydrocarbon compound according to [1], wherein the hydrocarbon compound is an alipid hydrocarbon compound having 2 to 6 carbon atoms. [3] The method for producing a hydrocarbon compound according to [1] or [2], wherein at least one of the metals is cobalt. [4] The method for producing a hydrocarbon compound according to any one of [1] to [3], wherein at least one of the metals is a basic metal. [5] The method for producing a hydrocarbon compound according to [4], wherein the basic metal is one or more selected from elements of groups I to III. [6] The method for producing a hydrocarbon compound according to any one of [1] to [5], wherein the carrier is a metal oxide. [7] The method for producing a hydrocarbon compound according to [6], wherein the metal oxide is one or more selected from alumina, silica, titania, zirconia, and ceria.

[0011] The present invention provides a method for producing hydrocarbon compounds that uses an inexpensive and long-lasting catalyst, has a high conversion rate of methane or carbon dioxide, and can produce a variety of hydrocarbon compounds.

[0012] This figure shows a plasma-based dry reforming methane apparatus used in the examples.

[0013] The present invention provides a method for producing hydrocarbon compounds (hereinafter referred to as "the present invention method"), characterized by irradiating carbon dioxide and methane with plasma in the presence of a solid catalyst in which two or more metals are supported on a carrier.

[0014] The metals used in a solid catalyst in which two or more of the above-mentioned metals are supported on a carrier may be a combination of two or more metals listed in the periodic table, but it is preferable that at least one of the metals is selected from group IX elements. Among such group IX elements, cobalt is preferred. Furthermore, it is preferable that at least one of the metals is selected from basic metals, and it is more preferable that the basic metal is selected from group I to III elements. Among group I to III elements, it is preferable that one or more be selected from potassium, calcium, and lanthanum.

[0015] In a solid catalyst in which two or more of the above-mentioned metals are supported on a carrier, it is preferable to combine one or more elements selected from group IX and one or more elements selected from basic metals, more preferably to combine cobalt with one or more elements selected from group I to III, even more preferably to combine cobalt with one or more elements selected from potassium, calcium, and lanthanum, and particularly preferably to combine cobalt with calcium.

[0016] The molar ratio of the two types of metals described above is not particularly limited, but for example, when combining one or more elements selected from group IX and one or more elements selected from basic metals, the ratio of one or more elements selected from basic metals to the amount of molars of group IX is 0.01 to 10, preferably 0.05 to 5. Also, when combining cobalt with one or more elements selected from group I to III, the ratio of one or more elements selected from group I to III to the amount of cobalt is 0.01 to 10, preferably 0.05 to 5. Furthermore, when combining cobalt with one or more elements selected from potassium, calcium, and lanthanum, the ratio of one or more elements selected from potassium, calcium, and lanthanum to the amount of cobalt is 0.01 to 10, preferably 0.05 to 5, more preferably 0.05 to 0.2.

[0017] The support used in a solid catalyst in which two or more of the above-mentioned metals are supported on a support is not particularly limited as long as it can support the above-mentioned metals, but examples include metal oxides and clay. Among these supports, metal oxides are preferred. As metal oxides, for example, one or more selected from alumina, silica, titania, zirconia, and ceria are preferred, with alumina being more preferred.

[0018] The shape of the carrier is not particularly limited and can be spherical, plate-shaped, porous, granular, etc. The size of the carrier is also not particularly limited; for example, if it is granular, the average particle diameter is 300 to 2000 μm, preferably 500 to 1000 μm. This average particle diameter is measured by laser diffraction scattering.

[0019] The method for supporting the two or more metals on the carrier is not particularly limited, and for example, impregnation, coprecipitation, ion exchange, equilibrium adsorption, etc., may be used. After supporting the metals on the carrier, drying, molding, firing, etc., may be performed as appropriate to achieve an average particle size of 300 to 2000 μm, preferably 500 to 1000 μm. When molding, a carrier material with an average particle size smaller than the above range may be used, for example, one with an average particle size of 5 to 100 μm, preferably 10 to 50 μm.

[0020] The amount of metal supported on the above carrier is not particularly limited, but for example, the total amount of the two types of metal is 0.01 to 100% by mass (hereinafter simply referred to as "%"), preferably 0.1 to 10%.

[0021] The following are preferred embodiments of the solid catalyst used in the manufacturing method of the present invention, in which two or more metals are supported on a carrier: Metals: Cobalt and calcium (0.05 to 0.2 parts calcium per 1 part cobalt, and 0.1 to 10% of the total amount of metal relative to the carrier) Carrier: Alumina (alumina with an average particle size of 10 to 50 μm is used as the carrier material, the above metals are supported on it, and then it is molded to form granules with an average particle size of 500 to 1000 μm)

[0022] In the present invention's manufacturing method, carbon dioxide and methane are irradiated with plasma in the presence of the solid catalyst. Plasma irradiation can be performed using a commonly used plasma-based dry reforming methane apparatus. Specifically, carbon dioxide, methane, and optionally an inert gas such as argon are introduced into a reaction furnace made of quartz or the like, and a plasma, preferably a non-equilibrium plasma, and more preferably a non-equilibrium plasma by dielectric barrier discharge, is generated using a plasma generator. The method of installing the solid catalyst in the reaction furnace is not particularly limited; for example, the solid catalyst can be sandwiched between quartz cotton, or placed in a quartz container. The installation position of the solid catalyst should be such that it is present in the plasma while the plasma is being generated. The amount of solid catalyst used in the present invention's manufacturing method is not particularly limited as long as it is packed so that it can efficiently contact the gas flowing through the reaction pathway, for example, 1 cm３ The solid catalyst should be packed in such a way that it amounts to approximately 0.5 to 1.5 g relative to the reaction field volume.

[0023] The amount of carbon dioxide and methane introduced into the reactor is not particularly limited, but the total flow rate should be 100 to 300 mL / min, preferably 150 to 250 mL / min. The ratio of carbon dioxide to methane is also not particularly limited, but 0.5 to 1.5:0.5 to 1.5 is preferred, and 1:1 is more preferred. When introducing an inert gas, 40 to 60%, preferably 50%, of the above total flow rate should be the inert gas.

[0024] The pressure of the reactor may be atmospheric pressure. The plasma generator is not particularly limited as long as it is a device that can generate plasma at atmospheric pressure, for example, one equipped with a high-voltage electrode, ground electrode, high-voltage probe, current transformer, oscilloscope, etc. The applied voltage for generating the plasma is not particularly limited, but for example, it is 10 to 20 kV, preferably 12 to 16 kV, and more preferably 14 kV. The power supply frequency for generating the plasma is also not particularly limited, but it is 10 to 14 kHz, preferably 11 to 13 kHz, and more preferably 12 kHz. The reactor may also be further connected to a cooling trap, pump, gas chromatograph, quadrupole mass spectrometer, or an analytical device such as a spectrometer may be installed externally.

[0025] The hydrocarbon compounds produced can be analyzed using analytical instruments such as gas chromatography connected to the above-mentioned reactor. Furthermore, this analysis allows for the calculation of methane and carbon dioxide conversion rates, hydrogen / carbon monoxide ratios, etc.

[0026] Furthermore, the state of the plasma can be analyzed using analytical devices such as spectrometers installed outside the reactor.

[0027] In the manufacturing method of the present invention, the plasma irradiation time (reaction time) is not particularly limited, but for example, it is 5 minutes or more, preferably 5 to 300 minutes, and more preferably 10 to 200 minutes. In the manufacturing method of the present invention, it is always necessary to irradiate with plasma when carrying out the reaction. In the manufacturing method of the present invention, even when the reaction is carried out under such long plasma irradiation, there is little carbide formation on the solid catalyst surface and the catalytic activity does not easily decrease. The carbide (carbon mass) deposited on the solid catalyst surface can be measured with a thermomass spectrometer (TG).

[0028] In the manufacturing method of the present invention, it is preferable to introduce hydrogen to generate a plasma before introducing methane and carbon dioxide into the reaction furnace, and to perform a reduction treatment with hydrogen plasma for 10 to 120 minutes, preferably 40 to 80 minutes.

[0029] The present invention method described above can produce hydrocarbon compounds from carbon dioxide and methane. The hydrocarbon compounds produced by the present invention method are not particularly limited and include, for example, aliphatic hydrocarbon compounds, alcohols, aldehydes, carboxylic acids, and other oxygen-containing hydrocarbon compounds. Alkaline hydrocarbon compounds include alkanes, alkenes, and alkynes. Among aliphatic hydrocarbon compounds, aliphatic hydrocarbon compounds having 2 to 6 carbon atoms are preferred, preferably aliphatic hydrocarbon compounds having 2 to 5 carbon atoms, more preferably aliphatic hydrocarbon compounds having 2 to 4 carbon atoms, and particularly preferably aliphatic hydrocarbon compounds having 2 to 3 carbon atoms. Specifically, aliphatic hydrocarbon compounds having 2 to 3 carbon atoms include ethylene, ethane, propylene, and propane. Alcohols include ethanol and propanol. Carboxylic acids include formic acid and acetic acid. Aldehydes include acetaldehyde.

[0030] The present invention will be described in detail below with reference to examples of the present invention, but the present invention is not limited in any way to these examples.

[0031] Example 1 Production of hydrocarbon compounds: Hydrocarbon compounds were produced from methane and hydrogen using the dry reforming methane apparatus 1 shown in Figure 1. The test conditions are as shown in Table 1. First, H ２Gas 2 was introduced into a reactor 4 (outer diameter 12 mm, inner diameter 10 mm, length 200 mm) through a mass flow meter 3, and non-equilibrium hydrogen plasma was generated for 1 hour to perform reduction treatment. Thereafter, Ar, CH ４ , CO ２ gases were each introduced into the reactor 4 through a mass flow meter 3. In the center of the reactor 4, 3.5 g of the solid catalyst described in Table 2 (which corresponds to the amount relative to a reaction field volume of 3.57 cm ３ ) was placed in advance by sandwiching it between quartz wool. After gas introduction, voltage was applied to a copper high-voltage electrode 11 to generate non-equilibrium plasma. The gas after reaction was passed through a cooling trap 13, then analyzed with a gas chromatograph (GC-TCD) 15 through a soap film flow meter 14. The conversion rate of CH ４ , the CO content, and the hydrocarbon compound content after 10 minutes and 200 minutes of reaction are values calculated from the values measured by the gas chromatograph, and are shown in Table 3. In Table 3, the reduction rate of conversion rate is the percentage reduction of the methane conversion rate after 200 minutes relative to the methane conversion rate after 10 minutes.

[0032]

[0033]

[0034] <Preparation of Solid Catalyst> In catalyst preparation, a powdery catalyst support (Al2O 3、 Strem Chemicals, Inc., product number 13-2525, average particle diameter 19 to 23 µm (600 to 850 mesh)) was loaded with a metal precursor by a wet impregnation method. A metal precursor typified by nitrates was used as the metal precursor. When two types of metal species were used, these metals were impregnated simultaneously. After impregnation, the product was dried at 120°C for 2 hours, adjusted to the specified particle diameter shown in Table 1 by pressure molding, and then calcined at 500°C for 3 hours to obtain a granular catalyst.

[0035]

[0036] From the above results, all solid catalysts prepared by supporting two types of metals on alumina exhibit lower CH ４exhibits a high conversion rate or a low reduction rate of conversion rate, which is excellent, and it has been found that various aliphatic hydrocarbon compounds (ethylene, ethane, propylene, propane) can be produced with long catalyst life. Among solid catalysts in which two types of metals are supported on alumina, when 1% of Co and Ca and 1% of Co and La are used, the reduction rate of conversion rate is particularly lower than that of a catalyst using Co alone, and it has been found that various aliphatic hydrocarbon compounds can be produced with long catalyst life. Furthermore, from the viewpoint of catalyst deterioration, it has been found that the case of using 1% Co and Ca is most preferable. It should be noted that, simultaneously with the production of the above aliphatic hydrocarbon compounds, the production of ethanol, propanol, formic acid, acetic acid and the like has been confirmed even in a trace amount, so it has also been found that not only aliphatic hydrocarbon compounds but also oxygen-containing hydrocarbon compounds such as alcohols and carboxylic acids can be produced. In addition, after completion of the reaction, the amount of deposited carbide on the surface of the solid catalyst in which two types of metals are supported on alumina was reduced compared to that of alumina alone or alumina supporting Co alone.

[0037] Example 2 Preparation of hydrocarbon compounds: Using the same apparatus and conditions as in Example 1, hydrocarbon compounds were produced from methane and hydrogen in the same manner except that the solid catalyst shown in Table 4 was used. The solid catalyst was prepared in the same manner as in Example 1. Various measurements were also carried out in the same manner as in Example 1. The results are shown in Table 5.

[0038]

[0039]

[0040] From the above results, in the solid catalyst in which two types of metals are supported on alumina, when the amount of the metal combined with Co is increased, in all cases, even after 200 hours of reaction, the CH ４It was found that the solid catalyst exhibited a high conversion rate or a low rate of decrease in the conversion rate, making it excellent for producing various aliphatic hydrocarbon compounds (ethylene, ethane, propylene, propane) with a long lifespan. In particular, when Co and 3% K were used as the solid catalyst, the rate of decrease in the conversion rate was especially low compared to Co alone, and it was found that various aliphatic hydrocarbon compounds could be produced with a long lifespan. Furthermore, since trace amounts of ethanol, propanol, formic acid, and acetic acid were also confirmed simultaneously with the production of the above aliphatic hydrocarbon compounds, it was found that not only aliphatic hydrocarbon compounds but also oxygen-containing hydrocarbon compounds such as alcohols and carboxylic acids could be produced. In addition, after the reaction was completed, the amount of deposited carbide on the surface of these solid catalysts was reduced compared to alumina alone or alumina supported with Co.

[0041] The present invention provides a method for producing hydrocarbon compounds that can be used to produce various hydrocarbon compounds from carbon resources other than fossil fuels.

[0042] 1. Dry reforming methane apparatus 2. Gas 3. Mass flow meter (MFC) 4. Reactor 5. Catalyst 6. Spectrometer 7. Plasma supplement 8. Oscilloscope 9. Current transformer 10. Ground electrode 11. High voltage electrode (HV electrode) 12. High voltage probe (HV probe) 13. Cooling trap 14. Soap film meter 15. Gas chromatograph (GC-TCD)

Claims

1. A method for producing hydrocarbon compounds, characterized by irradiating carbon dioxide and methane with plasma in the presence of a solid catalyst in which two or more metals are supported on a carrier.

2. The method for producing a hydrocarbon compound according to claim 1, wherein the hydrocarbon compound is an alipid hydrocarbon compound having 2 to 6 carbon atoms.

3. A method for producing a hydrocarbon compound according to claim 1, wherein at least one of the metals is cobalt.

4. A method for producing a hydrocarbon compound according to claim 1, wherein at least one of the metals is a basic metal.

5. The method for producing a hydrocarbon compound according to claim 4, wherein the basic metal is one or more selected from elements of groups I to III.

6. A method for producing a hydrocarbon compound according to claim 1, wherein the carrier is a metal oxide.

7. A method for producing a hydrocarbon compound according to claim 6, wherein the metal oxide is one or more selected from alumina, silica, titania, zirconia, and ceria.

Images