Method for producing c2 compounds

Abstract

To provide a method for producing at least one C2 compound selected from the group consisting of acetaldehyde and ethanol by reacting carbon dioxide and methane in a gas phase under the application of a voltage to a catalyst.SOLUTION: While an electric current is applied to a catalyst in which rhodium (Rh) is supported on a semiconductor carrier having a band gap of 2 to 6 eV, carbon dioxide and methane are reacted in the gas phase in the presence of the catalyst at a reaction temperature of 80 to 400°C.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for producing at least one C2 compound selected from the group consisting of acetaldehyde and ethanol. [Background technology]

[0002] Efforts regarding carbon dioxide capture and utilization, a type of greenhouse gas, have been attracting attention. There is also a need to develop effective ways to use methane, which is known to be a greenhouse gas like carbon dioxide, instead of using it as fuel. One of these effective ways to use it is to convert it into useful chemicals. However, since both carbon dioxide and methane are typical inert molecules, it is not easy to convert them using conventional catalytic technology. In recent years, electric field catalytic technology, which is characterized by applying a voltage to a catalyst to cause a reaction of inert molecules, has been developed as a method of converting inert molecules.

[0003] For example, Patent Document 1 describes an electric field applied catalytic reaction device that reacts a raw material gas consisting of methane contained in coke oven gas and carbon dioxide contained in steelworks by-product gas to produce carbon monoxide and hydrogen gas.

[0004] In Non-Patent Document 1, La 2 O 3 and ZrO 2 It is described that carbon monoxide, hydrogen, ethane and ethylene can be produced from carbon dioxide and methane by applying a voltage to the catalyst of this system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-206453 A [Non-patent literature]

[0006] [Non-Patent Document 1] Kazumasa Oshima et al., “Oxidative coupling of methane using carbon dioxide in an electric field over La-ZrO2 catalyst at low external temperature”, Fuel, 2013, vol. 107, pp. 879-881 Summary of the Invention [Problem to be solved by the invention]

[0007] There are no known electric field catalysts capable of synthesizing oxygen-containing organic compounds such as acetaldehyde and ethanol from carbon dioxide and methane.

[0008] The present disclosure provides a method for producing at least one C2 compound selected from the group consisting of acetaldehyde and ethanol by reacting carbon dioxide and methane in a gas phase by applying a voltage to a catalyst, and a catalyst used in the method. [Means for solving the problem]

[0009] The present inventors discovered that in a reaction between carbon dioxide and methane, acetaldehyde and ethanol are produced by applying a voltage under heating conditions to a catalyst in which rhodium (Rh) is supported on a semiconductor carrier, and thus completed the present invention.

[0010] That is, the contents of this disclosure relate to the following [1] to [8].

[0011] [1] A method for producing at least one C2 compound selected from the group consisting of acetaldehyde and ethanol, comprising the steps of: passing an electric current through a catalyst in which rhodium (Rh) is supported on a semiconductor carrier having a band gap of 2 to 6 eV; and reacting carbon dioxide and methane in the presence of the catalyst in a gas phase at a reaction temperature of 80 to 400°C. [2] The semiconductor support is CeO 2 , ZrO 2 , and TiO 2 The manufacturing method according to [1], comprising at least one selected from the group consisting of: [3] The method according to [1] or [2], wherein the amount of Rh supported in the catalyst is 0.05 to 10 parts by mass per 100 parts by mass of the semiconductor support. [4] The reaction is 0.02 to 250 W / g Rh+半導体担体 The manufacturing method according to any one of [1] to [3], wherein the voltage is applied so that [5] The method according to any one of [1] to [4], wherein the reaction temperature is 100 to 300° C. [6] The method according to any one of [1] to [5], wherein the space velocity of the reaction is 1,000 to 50,000 / h. [7] The molar ratio of carbon dioxide to methane in the reaction (CO 2 / CH 4 The method according to any one of [1] to [6], wherein the ratio of the total amount of the polymer to the total amount of the polymer is 0.05 to 20. [8] An electric field catalyst in which rhodium (Rh) is supported on a semiconductor support having a band gap of 2 to 6 eV, and which is used in the production of at least one C2 compound selected from the group consisting of acetaldehyde and ethanol using carbon dioxide and methane as raw materials. Effect of the Invention

[0012] According to the present invention, it is possible to provide a method for producing acetaldehyde and ethanol by proceeding with a reaction between carbon dioxide and methane by applying a voltage to a catalyst, and a catalyst used in the method. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of an apparatus used for the reaction of carbon dioxide and methane in Examples 1 to 8 and Comparative Examples 1 to 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments of the present invention will be described, but it should be understood that the present invention is not limited to these embodiments, and various applications are possible within the spirit and scope of the present invention. In this disclosure, when "~" is used to describe a numerical range, the numerical values ​​at both ends are the upper and lower limits, respectively, and are included in the numerical range.

[0015] (Catalyst for use in the reaction of carbon dioxide and methane and its manufacturing method) The reaction between carbon dioxide and methane uses an electric field catalyst in which Rh (rhodium) is supported on a semiconductor carrier.

[0016] In the present disclosure, the semiconductor carrier refers to a semiconductor carrier having a band gap of 2 to 6 eV. If the band gap is less than 2 eV, the resistance is too small to obtain an appropriate amount of power, and if it exceeds 6 eV, it is difficult to apply voltage due to the effects of discharge, etc., which is not preferable.

[0017] The semiconductor carrier is not particularly limited as long as it has a band gap of 2 to 6 eV, but it is preferable that the semiconductor carrier contains a metal oxide. 2 (3.3 eV), ZrO 2 (5.0 eV), TiO 2 (3.2 eV), Cu 2 It is preferable that the material contains at least one selected from the group consisting of CeO (2.1 eV) and ZnO (3.4 eV). 2 , ZrO 2 , and TiO 2 It is more preferable that the semiconductor carrier contains at least one selected from the group consisting of: The value in parentheses after the metal oxide is the band gap. The band gap value of the semiconductor carrier is measured by a conventionally known method such as a spectroscopic method.

[0018] The method for producing the semiconductor carrier is not particularly limited, and a commercially available carrier may be used as the semiconductor carrier.

[0019] The amount of Rh supported is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 1.0 parts by mass or more, preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 3.0 parts by mass or less, relative to 100 parts by mass of the semiconductor carrier. Any combination of these lower limit values ​​and upper limit values ​​may be used. For example, the amount of Rh supported is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 7 parts by mass, and even more preferably 1.0 to 3.0 parts by mass, relative to 100 parts by mass of the semiconductor carrier. When the amount of Rh supported is 0.05 parts by mass or more, the activity per unit catalyst mass or volume can be increased. When the amount of Rh supported is 10 parts by mass or less, the decrease in catalytic activity due to aggregation of Rh can be suppressed.

[0020] In one embodiment, the method for supporting Rh on a semiconductor carrier includes, in this order, a step of absorbing (impregnating) an aqueous solution of a Rh salt into the semiconductor carrier (impregnation step), a step of drying, a step of calcining, and a step of reducing. Other steps (e.g., an air drying step, a step of transferring from an impregnation device to a drying device, etc.) may be included between each step.

[0021] The Rh salt used in the impregnation step is not particularly limited, and for example, commercially available rhodium chloride trihydrate, pentaamminechlororhodium dichloride, rhodium nitrate, or a combination thereof can be used. The concentration of the Rh salt in the aqueous solution is determined from the volume of the aqueous Rh salt solution used in the impregnation step and the amount of Rh to be supported on the semiconductor carrier.

[0022] The conditions for the drying step are not particularly limited, but drying can generally be performed in air for 1 to 24 hours at 100 to 150° C. A commercially available dryer can be used for the drying treatment.

[0023] The conditions for the calcination step are not particularly limited, but calcination can generally be performed under air circulation for 0.5 to 12 hours at 400 to 600° C. For the calcination treatment, a commercially available calcination device such as a muffle furnace can be used.

[0024] The reduction step is carried out by applying hydrogen gas or a mixture of hydrogen gas and an inert gas (nitrogen gas, helium, etc.) to a catalyst precursor in which Rh salt is supported on a carrier at a space velocity (SV H2 The reduction step can be carried out by heating the gas at 300 to 600° C. for 1 to 5 hours while passing the gas through the reaction vessel at a flow rate of 4,000 to 16,000 / h. The reduction step is preferably carried out immediately before the reaction of carbon dioxide with methane in the reaction vessel.

[0025] (Production method of C2 compound) At least one C2 compound selected from the group consisting of acetaldehyde and ethanol is produced by reacting carbon dioxide and methane in the gas phase under heating conditions in the presence of a catalyst to which a voltage is applied and a current is passed.

[0026] This reaction is believed to proceed through the dry reforming reaction of carbon dioxide and methane (equation (1)), the formation reaction of acetaldehyde from carbon monoxide and hydrogen gas produced by the dry reforming reaction (equation (2)), and the formation reaction of ethanol (equation (3)). Therefore, it is necessary to set reaction conditions under which both the reaction of equation (1) and the reactions of equations (2) and (3) proceed.

[0027] CH 4 +CO 2 → 2CO+2H 2 (1) 2CO+3H 2 → CH 3 CH0 +H 2 O (2) 2CO+4H 2 → C 2 H 5 OH +H 2 O (3)

[0028] However, not all of the carbon monoxide and hydrogen gas produced in reaction (1) are always consumed in the reaction (2) or (3). Therefore, unreacted carbon monoxide or hydrogen gas that was produced in reaction (1) but did not react in reaction (2) or (3) may be discharged from the reactor. In addition, the reaction of reaction (2) or reaction (3) may consume the H produced in reaction (1). 2 More H 2 Therefore, the proportion of unreacted carbon monoxide exhausted from the reactor is greater than the proportion of unreacted hydrogen gas.

[0029] The reaction temperature is 80 to 400°C. The reaction temperature is preferably 100°C or higher, more preferably 150°C or higher, preferably 300°C or lower, and more preferably 270°C or lower. Any combination of these lower limit values ​​and upper limit values ​​may be used. For example, the reaction temperature is preferably 100 to 300°C, more preferably 150 to 270°C. A temperature below 80°C is not preferred because a sufficient current cannot be passed through the catalyst. A temperature above 400°C is not preferred because side reactions are promoted or aggregation of Rh species progresses. Without being bound by any theory, it is believed that by placing the electric field catalyst in a high-temperature environment, protons (H + ) is generated, and the resulting protons are thought to form the conductive paths necessary for catalyst activation.

[0030] The reaction pressure is preferably 0 to 5 MPaG (gauge pressure), more preferably 0.2 to 3 MPaG (gauge pressure), and even more preferably 0.5 to 1.5 MPaG (gauge pressure). If the reaction pressure is 0 to 5 MPaG (gauge pressure), side reactions are unlikely to proceed and the catalyst is highly stable, so that the reaction between carbon dioxide and methane can proceed efficiently.

[0031] The space velocity (gas flow rate (mL / h) / catalyst volume (mL)=1 / h) of the gas containing the reactant gas supplied to the reactor is preferably 1000 / h or more, more preferably 1500 / h or more, even more preferably 2000 / h or more, preferably 50000 / h or less, more preferably 30000 / h or less, and even more preferably 15000 / h or less. Any combination of these lower limit values ​​and upper limit values ​​may be used. For example, the space velocity of the gas containing the reactant gas is preferably 1000 to 50000 / h, more preferably 1500 to 30000 / h, and even more preferably 2000 to 15000 / h. If the space velocity is 1000 to 50000 / h, the time for the reactant gas to contact the catalyst can be sufficiently secured, and the reaction between carbon dioxide and methane can be efficiently promoted. The reaction between carbon dioxide and methane can be promoted without any problem even if an inert gas such as nitrogen or helium is simultaneously circulated.

[0032] (Reactant gas) The form of the reaction raw material gases carbon dioxide and methane is not particularly limited, and commercially available gases can be used. A mixed gas of the reaction raw material gas and an inert gas such as nitrogen gas or argon may be used for the reaction. In this case, it is preferable to set the ratio of the volume of the inert gas to the total volume of carbon dioxide and methane (volume of inert gas / volume of (carbon dioxide + methane)) to 0.9 or less from the viewpoint of efficient progress of the reaction.

[0033] The molar ratio of raw materials in the above reaction, i.e., the molar ratio of carbon dioxide and methane (CO 2 / CH 4 The raw material molar ratio is preferably 0.05 or more, more preferably 0.1 or more, even more preferably 0.5 or more, and preferably 20 or less, more preferably 8 or less, and even more preferably 4 or less. Any combination of these lower limit values ​​and upper limit values ​​may be used. For example, the raw material molar ratio is preferably 0.05 to 20, more preferably 0.1 to 8, and even more preferably 0.5 to 4. When the raw material molar ratio is 0.05 to 20, the reaction between carbon dioxide and methane can be efficiently promoted, and the reaction of carbon dioxide or methane alone can be prevented.

[0034] (Reaction Apparatus) The carbon dioxide and methane reaction apparatus includes a reaction tube for containing a catalyst and contacting the catalyst with carbon dioxide and methane, and a means for generating an electric field in the catalyst layer. A schematic diagram of a reaction apparatus used for the reaction of carbon dioxide and methane is shown in FIG. 1. FIG. 1 shows an example of a reaction apparatus for carbon dioxide and methane, and the structure of the reaction apparatus that can be used is not limited to this. In FIG. 1, the carbon dioxide and methane reaction apparatus 1 includes two electrodes 4 and 5 spaced apart from each other inside a reaction tube 3, and a catalyst is filled between the electrodes to form a catalyst layer 2. The two electrodes 4 and 5 include a high-voltage side electrode 4 to which a voltage is applied from a power source 6, and a ground side electrode 5 that is grounded. The electrodes 4 and 5 are formed of a metal mesh such as stainless steel to hold the catalyst and to pass the reaction raw material gas. The reaction tube 3 is formed of a non-conductive material to avoid conduction between the electrodes. The reaction apparatus 1 includes a heating means such as a heater 7 for heating the catalyst layer 2 and maintaining a predetermined reaction temperature.

[0035] The reaction tube 3 is generally made of a material that is non-conductive and does not affect the reaction between carbon dioxide and methane. A preferred material for the reaction tube 3 is, for example, quartz. The shape of the reaction tube 3 may be a shape other than a cylindrical shape as shown in FIG. 1. The size of the reaction tube 3 may be appropriately set depending on the required processing amount, and is not particularly limited. Various conditions such as the sizes of the high voltage side electrode 4 and the ground side electrode 5 and the amount of the catalyst layer 2 in the reaction tube 3 may be appropriately set depending on the size of the reaction tube 3, and are not particularly limited.

[0036] In the carbon dioxide and methane reactor 1, carbon dioxide and methane are supplied downward from the top of the reaction tube 3. At this time, a voltage is applied from a power source 6 between a high-voltage side electrode 4 and a ground side electrode 5, which are separated from each other, to generate an electric field, and a current is passed through the electrode, so that the reactant gas can be brought into contact with the catalyst layer 2 in the electric field. The applied voltage is preferably adjusted so that the power (W) applied to the catalyst layer 2 is 0.02 W or more and 250 W or less per gram of catalyst (total mass of supported Rh and semiconductor carrier). In other words, the applied voltage is preferably 0.02 W / gRh+半導体担体 More preferably, 0.1 W / g or more Rh+半導体担体 More preferably, 0.5 W / g Rh+半導体担体 More than 250W / g, preferably 250W / g Rh+半導体担体 Less than or equal to 150 W / g Rh+半導体担体 Less than 30W / g, more preferably Rh+半導体担体 For example, the voltage is preferably applied at 0.02 to 250 W / g. Rh+半導体担体 , more preferably 0.1 to 150 W / g Rh+半導体担体 , and more preferably 0.5 to 30 W / g Rh+半導体担体 The range is 0.02 to 250 W / g. Rh+半導体担体 If so, a voltage can be applied to the catalyst with a moderate amount of power, and the reaction between carbon dioxide and methane can be effectively promoted. EXAMPLES

[0037] 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.

[0038] (Preparation of Catalyst Precursor A) 3.6 g of an aqueous solution containing 0.255 g of rhodium chloride trihydrate was added to a commercially available CeO 2 Carrier (BET specific surface area: 93 m 2 The mixture was then dropped into 10 g of 100% sucrose (1.0 g / g) at room temperature. After kneading for 5 minutes, the mixture was dried at 120°C for 5 hours using a dryer. The mixture was then pulverized in an agate mortar for 5 minutes and calcined in air at 500°C for 3 hours using a muffle furnace. The resulting powder was sized to a mesh size of 300 to 500 μm to obtain catalyst precursor A.

[0039] (Preparation of Catalyst Precursor B) Catalyst precursor B is a commercially available ZrO 2 Reference catalyst provided by the Catalysis Society: JRC-ZRO-7 (BET specific surface area: 101 m 2 The catalyst precursor was prepared in the same manner as catalyst precursor A, except that the amount of the catalyst precursor was 10 g ( / g).

[0040] (Preparation of Catalyst Precursor C) Catalyst precursor C was prepared by using commercially available TiO 2 Sigma-Aldrich P-25 (BET specific surface area: 54 m 2 The catalyst precursor was prepared in the same manner as catalyst precursor A, except that the amount of the catalyst precursor was 10 g ( / g).

[0041] (Preparation of Catalyst Precursors D and E) Catalyst precursors D and E were prepared in the same manner as catalyst precursor A, except that the amount of rhodium chloride trihydrate added was changed so that the amount of Rh supported was as shown in Table 1.

[0042] (Preparation of Catalyst Precursor F) Catalyst Precursor F was prepared in the same manner as Catalyst Precursor A, except that 0.380 g of copper nitrate trihydrate was used instead of rhodium chloride trihydrate.

[0043] (Preparation of Catalyst Precursor G) Catalyst Precursor G was prepared in the same manner as Catalyst Precursor A, except that 0.455 g of zinc nitrate hexahydrate was used instead of rhodium chloride trihydrate.

[0044] (Preparation of catalyst precursor H) Catalyst precursor H was prepared in the same manner as catalyst precursor A, except that 0.157 g of silver nitrate was used instead of rhodium chloride trihydrate.

[0045] (Preparation of Catalyst Precursor I) Catalyst precursor I was prepared in the same manner as catalyst precursor A, except that 0.198 g of tetraammineplatinum nitrate was used instead of rhodium chloride trihydrate.

[0046] (Preparation of catalyst precursor J) Catalyst precursor J was prepared in the same manner as catalyst precursor A, except that 0.209 g of tetrachloroauric acid tetrahydrate was used instead of rhodium chloride trihydrate.

[0047] (Preparation of catalyst precursor K) Catalyst precursor K was prepared in the same manner as catalyst precursor B, except that 0.455 g of zinc nitrate hexahydrate was used instead of rhodium chloride trihydrate.

[0048] (Preparation of Catalyst Precursor L) The catalyst precursor L was prepared by using commercially available SiO 2 Fuji Silysia Chemical's CALiACT G-10 (BET specific surface area: 300 m 2 The catalyst precursor was prepared in the same manner as catalyst precursor A, except that the amount of the catalyst precursor was 10 g ( / g).

[0049] (Preparation of Catalyst Precursor M) The catalyst precursor M was prepared by using a commercially available Al 2 O 3 Sumitomo Chemical Co., Ltd. KHS-24 (BET specific surface area: 153 m 2 The catalyst precursor was prepared in the same manner as catalyst precursor A, except that the amount of the catalyst precursor was 10 g ( / g).

[0050] (Reaction of carbon dioxide and methane) The reaction between carbon dioxide and methane was carried out using a reaction apparatus 1 shown in FIG. 1. A cylindrical quartz reaction vessel with an outer diameter of 20 mm, an inner diameter of 9 mm, and a length of 260 mm was used as the reaction tube 3. 0.38 mL of the granulated catalyst precursor was filled on the ground side electrode 5 made of stainless steel mesh provided in the reaction tube 3, and the high voltage side electrode 4 made of stainless steel mesh was brought into contact with the upper part of the catalyst precursor to form a catalyst layer 2. The thickness of the catalyst layer 2 was 6 mm. A stainless steel rod with a diameter of 3.2 mm was used as the conductive wire connecting the high voltage side electrode 4 and the power source 6, and the conductive wire connecting the ground side electrode 5 and the earth. The high voltage side electrode 4 was electrically connected to the power source 6 (DC high voltage power source: HAR-10N30 manufactured by Matsusada Precision Co., Ltd.).

[0051] In the reactor 1, 3 NL / h of hydrogen gas and 12 NL / h of nitrogen gas were supplied from the top of the reaction tube 3, and the heater temperature was adjusted so that the temperature of the catalyst layer 2 was 450° C., and the gas was allowed to flow for 1 hour to reduce the catalyst precursor with hydrogen gas and convert it into each catalyst metal, thereby carrying out a reduction step. The temperature of the catalyst layer was measured by placing a thermocouple below the catalyst layer 2.

[0052] In the reactor 1, the reaction raw material gas (carbon dioxide gas and methane gas) was supplied from the top of the reaction vessel 3, the pressure in the reaction tube 3 was increased from normal pressure to 0.8 MPaG (gauge pressure), and the temperature of the catalyst layer 2 was increased to 180°C by the heater. Then, a current was passed from the power source 6 between the high-voltage side electrode 4 and the ground side electrode 5 to generate an electric field in the catalyst layer 2, thereby causing a reaction between carbon dioxide and methane. The supply amount of carbon dioxide gas was 0.57 NL / h, the supply amount of methane gas was also 0.57 NL / h (raw material molar ratio: 1.0), and the space velocity was 3000 / h. The current was passed at a constant value determined in each example shown in Table 1, and the temperature of the heater was adjusted so that the temperature of the catalyst layer 2 was the temperature shown in Table 1. At this time, the corresponding voltage was measured by the power source 5.

[0053] The reaction product gas discharged from the bottom of the reaction tube 3 was collected using a trap tube containing 70 g of pure water, and the products contained in the liquid product collected in the pure water and the gas product after passing through the trap tube were analyzed by gas chromatography.

[0054] (Method of Analyzing Liquid Products) 1. Acetaldehyde and ethanol 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 that had collected the liquid product, and 0.5 μL of this was injected into a gas chromatography analyzer and analyzed under the following conditions. Gas chromatograph: Agilent Technology 7890A Column: DB-WAX manufactured by Agilent Technology Co., Ltd. (length 30 m, inner diameter 0.32 mm, film thickness 0.5 μm) Carrier gas: Helium (split ratio: 11.8, column flow rate 3 mL / min) Temperature conditions: the detector temperature was 200°C, the vaporizer temperature was 220°C, and the column temperature was raised from 60°C to 200°C at a heating rate of 10°C / min and held at 200°C for 1 min. Detector: FID

[0055] (Method of Analyzing Gas Products) 1. Acetaldehyde and ethanol Using the absolute calibration curve method, 0.5 mL of the gas components were sampled and the entire amount was injected into a gas chromatography apparatus for analysis. The gas chromatography conditions were the same as those for the analysis of the liquid product described above.

[0056] 2. Hydrogen Using the absolute calibration curve method, 40 mL of gas components were collected and the entire amount was passed through a 1 mL gas sampler attached to a gas chromatography analyzer, and analysis was performed under the following conditions. Gas chromatograph: Agilent Technology 7890A Column: Agilent Technology 8Ft Molecular Sieve 5A 60 / 80 mesh (length 2.4m, inner diameter 2mm) Carrier gas: Nitrogen gas (split ratio: 80, column flow rate 2 mL / min) Temperature conditions: The temperature of the detector and vaporizer was set to 250°C, and the column temperature was kept at 50°C for 7 minutes from the start of the analysis, then it was heated to 75°C at a heating rate of 10°C / min and kept at 75°C for 1 minute, then it was heated to 145°C at a heating rate of 20°C / min and kept at 145°C for 3 minutes. Detector:TCD

[0057] 3. Carbon monoxide The gas sample was introduced into the gas chromatography apparatus in the same manner as in the hydrogen analysis described above. The gas chromatography analysis was carried out under the following conditions. Gas chromatograph: Agilent Technology 7890A Column: 6 Ft HayeSep Q 80 / 100 mesh, in Nickel (length 1.8 m, inner diameter 2 mm) manufactured by Agilent Technology Co., Ltd. and 8 Ft Molecular Sieve 5A 60 / 80 mesh (length 2.4 m, inner diameter 2 mm) manufactured by Agilent Technology Co., Ltd. Carrier gas: Helium (split ratio: 80, column flow rate 2 mL / min) Temperature conditions: The same as in the hydrogen analysis above. Detector:TCD

[0058] From the above analytical 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) / [catalyst (supported metal + support) volume (L) × reaction time (h)]

[0059] <Example 1> 0.38 mL of catalyst precursor A was filled into the reaction tube 3, and the reduction step was carried out, followed by the reaction of carbon dioxide with methane. After the reaction was carried out for 5 hours, the liquid product collected in the pure water and the gas product after passing through the trap tube were analyzed, and the space-time yields of carbon monoxide, hydrogen, acetaldehyde, and ethanol were calculated. The reaction conditions and results are shown in Table 1. Note that a volume change occurs when the catalytic metal salt is reduced to the catalytic metal, but since the mass of the catalytic metal is about 1 part by mass per 100 parts by mass of the support, which does not change in volume during the reduction step, the volume change was ignored to calculate the STY.

[0060] <Example 2> The reaction between carbon dioxide and methane was carried out in the same manner as in Example 1, except that the current was set to 10.0 mA, and the analysis was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0061] <Example 3> The reaction of carbon dioxide and methane was carried out in the same manner as in Example 1, except that the catalyst layer temperature was set to 250° C., and analysis was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0062] <Example 4> A reaction between carbon dioxide and methane was carried out in the same manner as in Example 1, except that catalyst precursor B was packed instead of catalyst precursor A, and analysis was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0063] <Example 5> The reaction of carbon dioxide and methane was carried out in the same manner as in Example 4 except that the catalyst layer temperature was set to 250° C., and analysis was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0064] <Examples 6 to 8> Carbon dioxide and methane were reacted and analyzed in the same manner as in Example 1, except that catalyst precursors C to E were packed instead of catalyst precursor A. The results are shown in Table 1.

[0065] <Comparative Example 1> The reaction between carbon dioxide and methane was carried out in the same manner as in Example 1, except that no voltage was applied, and the analysis was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0066] <Comparative Examples 2 to 6> Carbon dioxide and methane were reacted and analyzed in the same manner as in Example 1, except that catalyst precursors F to J were filled instead of catalyst precursor A and the current was set as shown in Table 1. The results are shown in Table 1.

[0067] <Comparative Example 7> Except for packing catalyst precursor K instead of catalyst precursor A and setting the catalyst layer temperature to 300° C., the reaction of carbon dioxide and methane was carried out in the same manner as in Example 1, and analysis was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0068] <Comparative Examples 8 to 9> Carbon dioxide and methane were reacted and analyzed in the same manner as in Example 1, except that catalyst precursors L and M were packed instead of catalyst precursor A. The results are shown in Table 1. Although a voltage of 0.30 kV was applied to the electrodes, no current flowed through the catalyst layer in either comparative example.

[0069] As shown in Table 1, when Example 1 is compared with Comparative Example 1, it is found that acetaldehyde and ethanol were produced by applying a voltage.

[0070] Moreover, it is clear from Examples 4 and 6 that acetaldehyde and ethanol were produced in the catalysts in which Rh was supported on various semiconductor supports.

[0071] From Examples 7 and 8, it can be seen that acetaldehyde and ethanol were produced even when using catalysts with different amounts of Rh supported.

[0072] In addition, it is clear from Examples 2 to 3 and Example 5 that acetaldehyde and ethanol were produced even under different conditions of temperature or current.

[0073] On the other hand, it is clear from Comparative Examples 2 to 7 that acetaldehyde and ethanol are not produced in the catalysts supporting metal species other than Rh.

[0074] Moreover, from Comparative Examples 8 and 9, it is seen that in a catalyst in which Rh is supported on a support having a band gap exceeding 6 eV, no current flows and the power required for producing acetaldehyde and ethanol cannot be supplied.

[0075] [Table 1] [Industrial Applicability]

[0076] INDUSTRIAL APPLICABILITY The present invention is a novel technology capable of producing acetaldehyde and ethanol from carbon dioxide and methane using an electric field catalyst, and is industrially useful. [Explanation of symbols]

[0077] 1: Carbon dioxide and methane reactor 2: Catalyst layer 3: Reaction tube 4: High voltage electrode 5: Ground electrode 6: Power supply 7: Heater

Claims

1. A method for producing at least one C2 compound selected from the group consisting of acetaldehyde and ethanol, the method comprising: passing an electric current through a catalyst in which rhodium (Rh) is supported on a semiconductor carrier having a band gap of 2 to 6 eV; and reacting carbon dioxide and methane in a gas phase in the presence of the catalyst at a reaction temperature of 80 to 400°C.

2. The semiconductor support is CeO ２ , ZrO ２ , and TiO ２ The method according to claim 1, further comprising at least one selected from the group consisting of:

3. 3. The method according to claim 1, wherein the amount of Rh supported in the catalyst is 0.05 to 10 parts by mass with respect to 100 parts by mass of the semiconductor support.

4. The reaction is performed at a rate of 0.02 to 250 W / g Ｒｈ＋半導体担体 The method according to claim 1 or 2, wherein the method is carried out by applying a voltage so that

5. The process according to claim 1 or 2, wherein the reaction temperature is 100 to 300° C.

6. The method according to claim 1 or 2, wherein the space velocity of the reaction is 1,000 to 50,000 / h.

7. The molar ratio of carbon dioxide to methane in the reaction (CO ２ / CH ４ The method according to claim 1 or 2, wherein the ratio is 0.05 to 20.

8. The electric field catalyst is used for producing at least one C2 compound selected from the group consisting of acetaldehyde and ethanol using carbon dioxide and methane as raw materials, and is formed by supporting rhodium (Rh) on a semiconductor support having a band gap of 2 to 6 eV.

Images