Method for producing oxygen-containing compound having two carbon atoms

Abstract

Provided is a method for producing at least one type of oxygen-containing compound having two carbon atoms which is selected from the group consisting of acetic acid, acetaldehyde, and ethanol with high efficiency by using carbon dioxide and methane as raw materials. The production method includes: a first reaction step for producing an intermediate gas containing carbon monoxide and hydrogen gas by reacting carbon dioxide with methane in a gas phase; and a second reaction step for producing an oxygen-containing compound having two carbon atoms in a gas phase from the intermediate gas using a catalyst having Rh carried thereon.

Description

Method for producing oxygen-containing compounds with 2 carbon atoms

[0001] This disclosure relates to a method for producing at least one oxygen-containing compound having two carbon atoms, selected from the group consisting of acetic acid, acetaldehyde, and ethanol, using carbon dioxide and methane as raw materials.

[0002] Efforts related to CCU (Carbon Dioxide Capture and Utilization), a technology for capturing and effectively utilizing carbon dioxide, a type of greenhouse gas, are attracting attention. Similarly, there is a need to develop effective utilization methods for methane, another greenhouse gas known to exist, as an alternative to its use as fuel. One possible method for the effective utilization of carbon dioxide and methane is conversion into useful chemicals. However, since both carbon dioxide and methane are typical inert molecules, conversion into useful chemicals using conventional catalyst technology is not easy.

[0003] Non-patent document 1 proposes a method using a zeolite catalyst to synthesize acetic acid, one of the oxygen-containing compounds with two carbon atoms, using carbon dioxide and methane as raw materials. In this document, a method is investigated in which a mixed gas of carbon dioxide and methane is reacted with a catalyst in which zinc is supported at 1 mmol / g on a zeolite, and the formation of acetic acid adsorbed species on the catalyst surface is observed by solid NMR measurement. Non-patent document 2 states that the equilibrium conversion rate of the reaction to synthesize acetic acid using carbon dioxide and methane as raw materials is 10 at 0.1 MPa. －９ It has been shown that the yield is on the order of moles. Patent Document 1 has confirmed that by using metal species elements such as Zn and Ni as modifiers for the zeolite catalyst and optimizing their content, acetic acid can be produced from carbon dioxide and methane in an amount on the order of nmols.

[0004] Patent Document 2 reports a method for producing synthesis gas (carbon monoxide and hydrogen gas) from carbon dioxide and lower hydrocarbons, and then using it to synthesize methanol. The methanol synthesized in this method is used to produce acetic acid or methyl methacrylate, and a manufacturing process integrating these steps is presented. Patent Document 3 reports a method for synthesizing acetic acid via methanol from synthesis gas produced by the partial oxidation of natural gas.

[0005] As catalysts for the reaction that produces synthesis gas containing carbon monoxide and hydrogen from a raw material gas containing carbon dioxide and methane, a catalyst in which nickel is supported on an alumina-containing support (Patent Document 4) and a catalyst in which at least one of rhodium and ruthenium is supported on a magnesium oxide support (Patent Document 5) have been proposed.

[0006] Japanese Patent Publication No. 2017-12950, ​​Japanese Patent Publication No. 2013-103909, Japanese Patent Publication No. 2017-124975, U.S. Patent No. 9,259,712, Japanese Patent Publication No. 2017-217629

[0007] J. Am. Chem. Soc. (2013), 135, 13567 ACS Catal. (2021), 11, 3384

[0008] Non-patent document 1 detects trace amounts of acetic acid adsorbed on the catalyst surface, but the yield is extremely low. As shown in non-patent document 2, the equilibrium conversion rate of the reaction to synthesize acetic acid using carbon dioxide and methane as raw materials is 10 at 0.1 MPa. －９ The yield is on the order of moles, making industrialization of this reaction extremely difficult. Although Patent Document 1 shows an improved yield compared to Non-Patent Document 1, the yield is still on the order of nmols, and further improvements are needed for industrial production of acetic acid. In addition, Patent Document 1 employs a reaction method in which carbon dioxide and methane, the raw materials, are alternately circulated through a reaction tube packed with a solid catalyst. Therefore, in order to ensure a certain yield, it is necessary to switch gases in a relatively short time, resulting in poor production efficiency from an industrial standpoint.

[0009] Patent documents 2 and 3 propose acetic acid production processes using natural gas as a raw material, but both consist of a three-stage reaction process in which synthesis gas is produced in the first reaction step, methanol is produced in the second reaction step, and acetic acid is produced in the third reaction step. As the number of reaction steps increases, the energy cost required for acetic acid production increases, so from an industrialization perspective, a process with fewer steps is desirable.

[0010] This disclosure provides a method for efficiently producing at least one oxygen-containing compound having two carbon atoms, selected from the group consisting of acetic acid, acetaldehyde, and ethanol, using carbon dioxide and methane as raw materials.

[0011] As a result of diligent research, the inventors have discovered that by combining a first reaction step of reacting carbon dioxide and methane to produce an intermediate gas containing carbon monoxide and hydrogen gas, and a second reaction step of producing a target product from the intermediate gas using a catalyst on which Rh is supported, at least one oxygen-containing compound with two carbon atoms selected from the group consisting of acetic acid, acetaldehyde, and ethanol can be efficiently produced, thus completing the present invention.

[0012] In other words, the contents of this disclosure relate to the following [1] to [6]. [1] A method for producing an oxygen-containing compound having two carbon atoms, comprising: a first reaction step of producing an intermediate gas containing carbon monoxide and hydrogen gas by reacting carbon dioxide and methane in the gas phase; and a second reaction step of producing a carbon-2 oxygen-containing compound having two carbon atoms from the intermediate gas in the gas phase using a catalyst supported with Rh, wherein the carbon-2 oxygen-containing compound having two carbon atoms is at least one selected from the group consisting of acetic acid, acetaldehyde, and ethanol. [2] The method for producing the product according to [1], wherein a refinery gas containing hydrogen gas is used as the methane raw material. [3] The method for producing the product according to [1] or [2], wherein the reaction temperature of the second reaction step is 100 to 400°C. [4] The method for producing the product according to any one of [1] to [3], wherein the reaction pressure of the second reaction step is 0.1 to 1.5 MPaG. [5] The manufacturing method according to any one of [1] to [4], wherein in the first reaction step, a catalyst is used in which at least one metal selected from Ni, Rh, and Ru is supported on a metal oxide support. [6] The manufacturing method according to any one of [1] to [5], wherein at least one selected from unreacted carbon dioxide, unreacted methane, carbon monoxide produced by the reaction, and hydrogen gas produced by the reaction is supplied to the first reaction step as a recycled raw material.

[0013] According to this disclosure, it is possible to provide an efficient method for producing at least one oxygen-containing compound having two carbon atoms, selected from the group consisting of acetic acid, acetaldehyde, and ethanol.

[0014] This is an example of a manufacturing process flow diagram for a method of producing an oxygen-containing compound with 2 carbon atoms according to one embodiment.

[0015] The embodiments of the present invention will be described below, but it should be understood that the present invention is not limited to these forms, and that various applications are possible within its spirit and scope of implementation. In this disclosure, when "~" is used for a numerical range, the numbers at both ends are the upper and lower limits, respectively, and are included in the numerical range. If multiple upper or lower limits are listed, a numerical range can be created from all combinations of upper and lower limits. Similarly, if multiple numerical ranges are listed, separate numerical ranges can be created by individually selecting and combining upper and lower limits from those numerical ranges.

[0016] (First reaction step: Production of intermediate gas) The first reaction step is a process to obtain an intermediate gas containing carbon monoxide and hydrogen gas from carbon dioxide and methane by a gas-phase reaction. As the reaction means, known methods can be used, but it is preferable to produce the intermediate gas mainly by the dry reforming reaction shown in the reaction formula (1) below.

[0017] The forms of carbon dioxide and methane used as raw materials are not particularly limited, and commercially available gases can be used. Unreacted carbon dioxide and methane can also be recovered and used as recycled raw materials. Refinery gas may be used as the methane raw material. Refinery gas refers to the mixed gas produced in the petroleum refining process and contains at least methane gas and hydrogen gas. In this case, a reaction in which carbon monoxide is produced from carbon dioxide by the reverse water-gas shift reaction shown in reaction equation (2) consumes hydrogen and proceeds in part. Furthermore, the water produced by reaction equation (2) reacts with methane by the steam reforming reaction shown in reaction equation (3), so that some of the methane is converted into carbon monoxide and hydrogen gas. To control the composition of the intermediate gas, water may be added to the raw materials so that some of the methane is converted into carbon monoxide and hydrogen gas by the steam reforming reaction shown in reaction equation (3).

[0018] CO ２ + CH ４ → 2CO + 2H ２ ... (1) CO ２ + H ２→ CO + H ２ O ・・・(2) H ２ O + CH ４ → CO + 3H ２ ・・・(3)

[0019] The dry reforming reaction proceeds at 700 to 900 °C using a catalyst, but at a high temperature exceeding 1000 °C, the reaction proceeds thermally even without a catalyst. From the perspective of energy conservation, the use of a catalyst is desirable. As the catalyst, a catalyst in which a metal is supported on a metal oxide carrier is preferable. Examples of the metal oxide carrier include silica, alumina, and magnesium oxide. Examples of the supported metal include at least one metal selected from Ni (nickel), Rh (rhodium), and Ru (ruthenium). Examples of such a catalyst include a catalyst in which nickel is supported on a carrier containing alumina described in Patent Document 4, and a catalyst in which at least one of rhodium and ruthenium is supported on a magnesium oxide carrier described in Patent Document 5.

[0020] The intermediate gas obtained in the first reaction step may contain at least one selected from carbon dioxide and methane, which are unreacted raw materials, in addition to carbon monoxide and hydrogen gas, which are reaction products. The intermediate gas may contain an inert gas such as nitrogen gas or argon gas. The unreacted raw material gas contained in the intermediate gas may be fed to the second reaction step without separation. In this case, from the perspective of reaction efficiency, the ratio of the total volume of the unreacted raw material gas (CO ２ and CH ４ ) to the total volume of the product gas (CO and H ２ ) (volume of unreacted raw material gas / volume of product gas) is preferably 0.9 or less, and the lower the better. At least one selected from unreacted carbon dioxide, unreacted methane, carbon monoxide generated by the reaction, and hydrogen gas generated by the reaction may be supplied as a recycled raw material to the first reaction step. The unreacted raw material gas may be purified and separated and recycled to the first reaction step. Examples of the purification and separation method include gas absorption, membrane separation, and cryogenic separation.

[0021] The reaction conditions in the first reaction step are not particularly limited. The reaction temperature is preferably 400 to 1200°C. In this disclosure, the reaction temperature refers to the temperature downstream of the catalyst layer, near the center of the channel cross-section during the reaction. The reaction temperature is more preferably 500°C or higher, and even more preferably 600°C or higher. The reaction temperature is more preferably 1100°C or lower, and even more preferably 1000°C or lower. Any combination of these lower and upper limits is acceptable.

[0022] The reaction pressure in the first reaction step is preferably 0 to 10 MPaG (gauge pressure). More preferably, the reaction pressure is 0.05 MPaG or higher, and even more preferably 0.1 MPaG or higher. More preferably, the reaction pressure is 8 MPaG or lower, and even more preferably 5 MPaG or lower. Any combination of these lower and upper limits is acceptable.

[0023] The space velocity SV (gas flow rate (mL / h) / catalyst volume (mL) = 1 / h) of the gas supplied to the reactor in the first reaction step, on a standard-state basis, is preferably 1000 / h or more, more preferably 1500 / h or more, and even more preferably 2000 / h or more. The space velocity is preferably 50000 / h or less, more preferably 30000 / h or less, and even more preferably 15000 / h or less. Any combination of these lower and upper limits is acceptable.

[0024] (Second reaction step: Production of a 2-carbon oxygen-containing compound from an intermediate gas) The second reaction step is a process for producing a 2-carbon oxygen-containing compound from an intermediate gas containing carbon monoxide and hydrogen gas. The 2-carbon oxygen-containing compound is at least one compound selected from the group consisting of acetic acid, acetaldehyde, and ethanol. The second reaction step uses a gas-phase reaction with a rhodium-supported catalyst.

[0025] In the second reaction step, oxygen-containing compounds with two carbon atoms are mainly produced by the reactions shown in the following reaction equations (4) to (6): 2CO + 2H ２ → CH ３ COOH...(4) 2CO + 3H ２ → CH ３CHO + H ２ O ··· (5) 2CO + 4H ２ → CH ３ CH ２ OH + H ２ O ··· (6)

[0026] (Catalyst and its manufacturing method) In the second reaction step, a catalyst supported with Rh (rhodium) is used.

[0027] The supported amount of Rh (metallic rhodium) is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, still more preferably 1.0 parts by mass or more, preferably 10 parts by mass or less, more preferably 7 parts by mass or less, still more preferably 5.0 parts by mass or less, with respect to 100 parts by mass of the carrier. Any combination of these lower limit values and upper limit values may be used. For example, the supported amount of Rh is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 7 parts by mass, still more preferably 1.0 to 5.0 parts by mass, with respect to 100 parts by mass of the carrier. When the supported amount of Rh is 0.05 parts by mass or more, the activity per unit catalyst mass or volume can be increased. When the supported amount of Rh is 10 parts by mass or less, a decrease in catalyst activity due to aggregation of Rh can be suppressed.

[0028] The carrier is not particularly limited, but is preferably a metal oxide. Examples of the metal oxide include zeolite, silica, alumina, silica-alumina, diatomaceous earth, montmorillonite, titania, ceria, molybdenum trioxide, vanadium pentoxide, and tungsten oxide, and zeolite, silica, and silica-alumina are preferred.

[0029] The manufacturing method of the carrier is not particularly limited. A commercially available carrier can also be used as the carrier.

[0030] The method for supporting Rh on the carrier is not particularly limited, but for example, methods such as impregnation, ion exchange, and coprecipitation can be used, and the supporting method can be selected according to the carrier. These supporting steps can be combined with steps such as a drying step, a firing step, a reduction step, and an alkali treatment step, and other steps may be included between each step. Examples of other steps include an air drying step, a transfer step from an impregnation apparatus to a drying apparatus, and a washing step.

[0031] As a preferable method for producing the catalyst supported with Rh, for example, there is a method of impregnating a carrier with a solution of a Rh salt as a Rh precursor (also referred to as an impregnation solution), or supporting rhodium ions on the carrier by ion exchange using the impregnation solution, followed by a drying step, a firing step, and a reduction step to obtain a catalyst in which Rh is supported on the carrier. Further, an alkali treatment step may be performed after the reduction step, and the firing step and the reduction step may be performed again. By performing the alkali treatment step, the catalytic activity can be improved.

[0032] The Rh salt used for the support is not particularly limited, and for example, rhodium chloride trihydrate, pentaamminechlororhodium dichloride, rhodium nitrate, or a combination thereof can be used. The concentration of the Rh salt in the impregnation solution is determined from the volume of the impregnation solution and the amount of Rh to be supported on the carrier.

[0033] The conditions of the drying step are not particularly limited, but generally, it can be dried in air at room temperature (23 °C) to 150 °C, or 100 to 150 °C for 1 to 24 hours. A commercially available dryer can be used for the drying treatment.

[0034] The conditions of the firing step are not particularly limited, but generally, it can be fired under air circulation at 400 to 600 °C for 0.5 to 12 hours. A commercially available firing apparatus such as a muffler furnace can be used for the firing treatment. In the firing step, the Rh salt becomes an oxide.

[0035] The reduction step is to pass hydrogen gas or a mixed gas of hydrogen gas and an inert gas through a catalyst precursor supported with Rh oxide, and heat it at 300 to 600 °C for 1 to 5 hours while flowing the gas with a space velocity (SV Ｈ２ ) of hydrogen gas of 4000 to 16000 / h. Examples of the inert gas include nitrogen gas and helium. The reduction step is preferably performed immediately before the reaction in the reaction vessel.

[0036] The alkaline treatment step can be carried out, for example, by contacting the catalyst with an alkaline aqueous solution. The pH of the alkaline aqueous solution is, for example, 8 to 12. After the alkaline treatment step, a washing step may be performed. In the washing step, the catalyst can be washed with water or the like.

[0037] In the second reaction step, the reaction temperature is preferably 100 to 400°C. More preferably, the reaction temperature is 150°C or higher, and even more preferably 200°C or higher. More preferably, the reaction temperature is 350°C or lower, and even more preferably 300°C or lower. Any combination of these lower and upper limits is acceptable. For example, the reaction temperature is preferably 150 to 350°C, and more preferably 200 to 300°C.

[0038] In the second reaction step, the reaction pressure is preferably 0.1 to 1.5 MPaG (gauge pressure). More preferably, the reaction pressure is 0.2 MPaG or higher, and even more preferably 0.5 MPaG or higher. More preferably, the reaction pressure is 1.2 MPaG or lower, and even more preferably 1 MPaG or lower. Any combination of these lower and upper limits is acceptable. For example, the reaction pressure is preferably 0.2 to 1.2 MPaG, and more preferably 0.5 to 1 MPaG.

[0039] The space velocity SV (gas flow rate (mL / h) / catalyst volume (mL) = 1 / h) of the intermediate gas supplied to the reactor in the second reaction step, converted to standard conditions, is preferably 1,000 to 50,000 / h, more preferably 5,000 to 20,000 / h, and even more preferably 10,000 to 20,000 / h. If the space velocity is 1,000 to 50,000 / h, sufficient time is ensured for the reaction raw material gases, carbon monoxide and hydrogen gas, to come into contact with the catalyst in the second reaction step, allowing the reaction between carbon monoxide and hydrogen gas to proceed efficiently. The reaction between carbon monoxide and hydrogen gas can proceed without problems even if unreacted gases from the first reaction step, such as carbon dioxide and methane, and inert gases such as nitrogen and helium, are simultaneously flowed through the gas. Note that the space velocity in the second reaction step is a value calculated based on the intermediate gas containing carbon monoxide, hydrogen gas, and optionally any unreacted gases and inert gases from the first reaction step.

[0040] The molar ratio of carbon monoxide to hydrogen gas in the intermediate gas during the second reaction step (CO / H ２ The molar ratio of carbon monoxide to hydrogen gas (CO / H) is preferably 0.05 or higher, more preferably 0.1 or higher, and even more preferably 0.5 or higher. ２ The molar ratio of carbon monoxide to hydrogen gas (CO / H) is preferably 20 or less, more preferably 8 or less, and even more preferably 4 or less. Any combination of these lower and upper limits is acceptable. For example, the molar ratio of carbon monoxide to hydrogen gas (CO / H) ２ The molar ratio of carbon monoxide to hydrogen gas (CO / H) is preferably 0.05 to 20, more preferably 0.1 to 8, and even more preferably 0.5 to 4. ２ When the ratio is between 0.05 and 20, the reaction for efficiently synthesizing oxygen-containing compounds from the intermediate gas can proceed.

[0041] The unreacted gas from the second reaction step can be supplied to the first reaction step as a recycled material. The unreacted gas from the second reaction step may contain unreacted carbon dioxide and methane, as well as carbon monoxide and hydrogen gas produced in the first reaction step. These may be purified and separated, and desired components may be selectively recycled.

[0042] (Manufacturing Process) Referring to Figure 1, an exemplary process flow of a method for producing a carbon-2 oxygen-containing compound according to one embodiment will be described. Figure 1 is an example of a manufacturing process flow diagram. In Figure 1, the reaction raw material gas 0 containing carbon dioxide and methane is supplied to the preheater 1. The reaction raw material gas preheated in the preheater 1 is supplied to the first reactor 2, where an intermediate gas containing carbon monoxide and hydrogen gas is produced. The produced intermediate gas is supplied to the second reactor 4 via the cooler 3, where a carbon-2 oxygen-containing compound is produced. The reaction product gas exiting the second reactor 4 is separated in the gas-liquid separator 5 into a crude product 6 containing at least one selected from the group consisting of acetic acid, acetaldehyde, and ethanol, and a gas component containing unreacted gas 9 from the second reaction step. The unreacted gas 9 from the second reaction step is supplied to the preheater 1 and cooler 3 via the gas scrubbing tower 7 and can be reused in the first and second reaction steps. The unreacted gas 8 from the first reaction step is supplied to the preheater 1 and can be reused in the first reaction step. However, the present invention is not limited in any way by the flow shown in Figure 1. As shown in the process flow of Figure 1, the unreacted gas 9 from the second reaction step can be supplied as a recycled material to at least one selected from the first and second reaction steps. The unreacted gas 9 from the second reaction step may contain components such as carbon dioxide, methane, carbon monoxide, and hydrogen. These may be purified and separated by methods such as gas absorption, membrane separation, and cryogenic separation. For example, carbon dioxide and methane from the purified and separated unreacted gas 9 from the second reaction step can be selectively recycled to the first reaction step, and carbon monoxide and hydrogen to the second reaction step. By-products from other manufacturing processes can also be used as raw materials. There are no restrictions on the sources of raw materials for the first and second reaction steps.

[0043] The present invention will be further described with reference to the following examples and comparative examples, but the present invention is not limited to these examples.

[0044] (Preparation of catalyst precursor A for the second reaction step) 2.0 g of NaY-type zeolite (HSZ-320NAA) manufactured by Tosoh Corporation was suspended in 1.8 L of ultrapure water. An aqueous solution of 0.353 g of pentaamminechlororhodium(III) dichloride dissolved in 0.1 L of ultrapure water was added dropwise to the suspension, and the mixture was stirred at room temperature for 24 hours to perform ion exchange. After recovering the ion-exchanged powder by filtration, it was washed three times with 0.6 L of ultrapure water. After air-drying the washed powder, it was calcined in a muffle furnace at 500°C under an air stream for 2 hours. The calcined powder was reduced at 450°C under a hydrogen stream for 2 hours. The reduced powder was added to 1 L of an aqueous solution adjusted to pH = 11 using sodium hydroxide, and stirred for 24 hours. After recovering the alkali-treated powder by filtration, it was washed twice with 0.6 L of ultrapure water. Due to the alkali treatment and washing, the Na in the catalyst was reduced. ＋ The content decreased. The washed powder was calcined in a muffle furnace at 500°C in air for 2 hours. The resulting powder was granulated to a mesh size of 300-500 μm to obtain catalyst precursor A. The Rh loading amount was confirmed to be 4.1% by mass using ICP-OES.

[0045] A reduction process was carried out in which catalyst precursor A was reduced with hydrogen gas to metallic rhodium by supplying 3 NL / h and nitrogen gas to 12 NL / h to a stainless steel reaction tube with an inner diameter of 10 mm filled with catalyst precursor A, and the heater temperature was adjusted to reach a catalyst layer temperature of 400°C, and the mixture was passed through for 1 hour, thereby producing catalyst A in which metallic rhodium is supported on a zeolite.

[0046] (Reaction of the second reaction step using simulated gas) The first reaction step is a step to obtain an intermediate gas containing carbon monoxide and hydrogen gas from carbon dioxide and methane, and known methods described in Patent Documents 4 and 5 can be used. Therefore, assuming the intermediate gas composition obtained at a certain reaction progress by the dry reforming reaction of carbon dioxide and methane, the reaction evaluation of the second reaction step was carried out using a simulated gas adjusted to a certain composition according to the reaction progress. Specifically, the above-mentioned simulated gas was supplied as an intermediate gas to a reactor filled with catalyst A obtained by reducing catalyst precursor A, the pressure was increased to 0.8 MPaG (gauge pressure), and after raising the temperature of the catalyst layer to 250°C with a heater, the reaction of the intermediate gas was carried out. The space velocity of the intermediate gas was set to 15000 / h.

[0047] The resulting reaction product gas was collected using a trap tube containing 70 g of pure water. The liquid product collected in the pure water and the gas product after passing through the trap tube were analyzed by gas chromatography.

[0048] (Analysis method for liquid products) 1. Acetic acid, acetaldehyde, ethanol, ethyl acetate, and other oxygen-containing compounds (methanol, methyl acetate, propionaldehyde, and dimethyl ether) Using the internal standard method, 0.1 g of 1,4-dioxane was added as an internal standard to 10 g of the solution in the trap tube from which the liquid products were collected. 0.5 μL of this solution was injected into a gas chromatography analyzer and analyzed under the following conditions. Gas chromatography analyzer: Agilent Technology Co., Ltd. 7890A Column: Agilent Technology Co., Ltd. DB-WAX (length 30m, inner diameter 0.32mm, film thickness 0.5μm) Carrier gas: Helium (split ratio: 11.8, column flow rate 3mL / min) Temperature conditions: Detector temperature 200°C, vaporization chamber temperature 220°C, column temperature raised from 60°C to 200°C at a heating rate of 10°C / min, and held at 200°C for 1min. Detector: FID

[0049] (Analysis Method for Gas Products) 1. Acetic acid, acetaldehyde, ethanol, ethyl acetate, and other oxygen-containing compounds (methanol, methyl acetate, propionaldehyde, and dimethyl ether) Using the absolute calibration curve method, 0.5 mL of the gas component was collected and the entire volume was injected into a gas chromatograph for analysis. The gas chromatography conditions were the same as those for the analysis of the liquid products described above.

[0050] 2. Hydrocarbons (methane, ethane, ethylene, propylene, n-butane, iso-butane, 1-butene, trans-2-butene, cis-2-butene, and iso-butene) Using the absolute calibration curve method, 40 mL of gaseous components were collected and the entire volume was passed through a 1 mL gas sampler attached to a gas chromatography analyzer. Analysis was performed under the following conditions: Gas chromatography analyzer: 7890A manufactured by Agilent Technology Co., Ltd. Column: DB-1 manufactured by Agilent Technology Co., Ltd. (length 2.0 m, inner diameter 0.32 mm) and HP-PLOT Al manufactured by Agilent Technology Co., Ltd. ２ O ３ Column S (length 25 m, inner diameter 0.32 mm) Carrier gas: Helium (split ratio: 80, column flow rate 2 mL / min) Temperature conditions: The temperature of the detector and vaporization chamber was set to 250°C. The column temperature was maintained at 50°C for 7 minutes from the start of analysis, then increased to 75°C at a heating rate of 10°C / min, and held at 75°C for 1 min. Then increased to 145°C at a heating rate of 20°C / min, and held at 145°C for 3 min. Detector: FID

[0051] Based on the above analysis results, the space-time yield (STY) of each product was calculated. The calculation method is as follows: Product STY (g / L·h) = Amount of product produced (g) / [Volume of catalyst (supported metal + carrier) (L) × Reaction time (h)]

[0052] (Example 1) 1 mL of catalyst precursor A was packed into a reaction tube, and catalyst A was prepared by reducing catalyst precursor A using the method described above. Then, the second reaction step was carried out using a simulated gas as an intermediate gas. Conversion rate of the dry reforming reaction in the first reaction step = 15%, CO / H ２Assuming a ratio of 1, the supply rates of intermediate gases were set to 5.5 NL / h for carbon dioxide, 5.5 NL / h for methane, 2.0 NL / h for carbon monoxide, and 2.0 NL / h for hydrogen. The space velocity SV of the intermediate gases was 15000 / h. After the reaction was carried out for 6 hours, the liquid products collected in pure water and the gas products after passing through the trap pipe were analyzed, and the space-time yields of acetic acid, acetaldehyde, and ethanol were calculated. The reaction conditions and results are shown in Table 1. Although a volume change occurs when the catalyst metal salt is reduced to the catalyst metal, the mass of the catalyst metal is approximately 4 parts by mass per 100 parts by mass of the carrier, which does not change volume in the reduction step, so the volume change was ignored when calculating the space-time yield.

[0053] (Example 2) Conversion rate of the dry reforming reaction in the first reaction step = 33%, CO / H ２ Assuming a ratio of 1, the reaction was carried out in the same manner as in Example 1, except that the supply rates of intermediate gases were set to 3.8 NL / h for carbon dioxide, 3.8 NL / h for methane, 3.7 NL / h for carbon monoxide, and 3.7 NL / h for hydrogen. Analysis was performed using the same method as in Example 1. The space velocity SV of the intermediate gas was 15000 / h. The reaction conditions and results are shown in Table 1.

[0054] (Example 3) Conversion rate of the dry reforming reaction in the first reaction step = 100%, CO / H ２ Assuming a ratio of 1, the reaction was carried out in the same manner as in Example 1, except that the supply rates of the intermediate gases were set to 7.5 NL / h for carbon monoxide and 7.5 NL / h for hydrogen gas. Analysis was performed using the same method as in Example 1. The space velocity SV of the intermediate gas was 15000 / h. The reaction conditions and results are shown in Table 1.

[0055] (Comparative Example 1) Assuming that the first reaction step was not performed and the second reaction step was performed using carbon dioxide gas and methane gas as raw materials, the reaction was carried out in the same manner as in Example 1, except that the supply rates of the raw material gases were set to 7.5 NL / h for carbon dioxide gas and 7.5 NL / h for methane gas, and the analysis was performed using the same method as in Example 1. The reaction conditions and results are shown in Table 1.

[0056] As shown in Table 1, comparing Examples 1-3 with Comparative Example 1, it can be seen that acetic acid, acetaldehyde, and ethanol were produced in the Examples. This shows that acetic acid, acetaldehyde, and ethanol can be obtained by using carbon dioxide and methane as raw material gases and going through a process that combines the first and second reaction steps. Note that the selectivity in Table 1 is a value calculated based on the number of carbon atoms in the product.

[0057]

[0058] The manufacturing method disclosed herein is a novel method that can efficiently produce at least one oxygen-containing compound having two carbon atoms, selected from the group consisting of acetic acid, acetaldehyde, and ethanol, using carbon dioxide and methane as raw materials, and is industrially useful.

[0059] 0: Reactant gas 1: Preheater 2: First reactor 3: Cooler 4: Second reactor 5: Gas-liquid separator 6: Crude products (acetic acid, acetaldehyde, and ethanol) 7: Gas scrubbing tower 8: Unreacted gas from the first reaction step 9: Unreacted gas from the second reaction step

Claims

1. A method for producing an oxygen-containing compound having two carbon atoms, comprising: a first reaction step of producing an intermediate gas containing carbon monoxide and hydrogen gas by reacting carbon dioxide and methane in the gas phase; and a second reaction step of producing a carbon-2 oxygen-containing compound having two carbon atoms from the intermediate gas in the gas phase using a catalyst supported with Rh, wherein the carbon-2 oxygen-containing compound having two carbon atoms is at least one selected from the group consisting of acetic acid, acetaldehyde, and ethanol.

2. The manufacturing method according to claim 1, wherein a refinery gas containing hydrogen gas is used as a methane raw material.

3. The manufacturing method according to claim 1 or 2, wherein the reaction temperature of the second reaction step is 100 to 400°C.

4. The manufacturing method according to claim 1 or 2, wherein the reaction pressure of the second reaction step is 0.1 to 1.5 MPaG.

5. The manufacturing method according to claim 1 or 2, wherein in the first reaction step, a catalyst is used in which at least one metal selected from Ni, Rh, and Ru is supported on a metal oxide support.

6. The manufacturing method according to claim 1 or 2, wherein at least one selected from unreacted carbon dioxide, unreacted methane, carbon monoxide produced by the reaction, and hydrogen gas produced by the reaction is supplied to the first reaction step as a recycled material.

Images