Additives and electrolytes for ethylene production

Abstract

Provided is an additive for ethylene production that can improve the selectivity of ethylene production in the electrochemical reaction of a carbon source containing at least one of carbon monoxide and carbon dioxide. The present invention provides an additive for producing ethylene from a carbon source containing at least one of carbon monoxide and carbon dioxide, which comprises a compound represented by formula (1): 1 represents a hydrogen atom, a halogen atom, an amino group which may have a substituent, a hydroxy group, a cyano group, a thiol group, an alkyl group which may have a substituent and has 1 to 10 carbon atoms, an alkoxy group which may have a substituent and has 1 to 10 carbon atoms, or an aryl group which may have a substituent and has 6 to 10 carbon atoms. TIFF0007812533000012.tif2824

Description

[Technical Field]

[0001] The present invention relates to an additive and an electrolyte for ethylene production. [Background technology]

[0002] The process of converting carbon dioxide through electrochemical reactions has attracted attention, and copper electrodes are known as electroreduction electrodes that exhibit relatively good selectivity for conversion to hydrocarbons. However, even when copper electrodes are used, the selectivity for hydrocarbons and the suppression of the competing reaction, hydrogen production, are not necessarily sufficient, and further improvements are desired (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-108575 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrochemical production of ethylene, which is important in the chemical industry, from carbon dioxide, the selectivity to ethylene during electrolysis of carbon dioxide using a copper electrode has not been sufficient. One aspect of the present invention aims to provide an additive for ethylene production that can improve the selectivity of ethylene production in the electrochemical reaction of a carbon source containing carbon dioxide. [Means for solving the problem]

[0005] Specific means for solving the above problems are as follows, and the present invention includes the following aspects.

[0006] [1] An additive for producing ethylene from a carbon source containing at least one of carbon monoxide and carbon dioxide, comprising a compound represented by the following formula (1) or a tautomer thereof:

[0007] [ka]

[0008] In general formula (1), R 1 represents a hydrogen atom, a halogen atom, an amino group which may have a substituent, a hydroxy group, a cyano group, a thiol group, an alkyl group which may have a substituent and has 1 to 10 carbon atoms, an alkoxy group which may have a substituent and has 1 to 10 carbon atoms, or an aryl group which may have a substituent and has 6 to 10 carbon atoms.

[0009] [2] R in Equation (1) 1 is a hydrogen atom, an amino group, a monoalkylamino group having 1 to 10 carbon atoms, a dialkylamino group having 1 to 10 carbon atoms, an alkylaminoalkyl group having 1 to 10 carbon atoms, or an aminoalkyl group having 1 to 10 carbon atoms.

[0010] [3] The additive for ethylene production according to [1] or [2], which is used for the electrolytic reduction reaction of the carbon source.

[0011] [4] An electrolytic solution comprising the additive for ethylene production according to any one of [1] to [3], an electrolyte, and a liquid medium. [Effects of the Invention]

[0012] According to one aspect of the present invention, an additive for ethylene production can be provided that can improve the selectivity of ethylene production in the electrochemical reaction of a carbon source containing at least one of carbon monoxide and carbon dioxide. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic perspective view showing an example of an electrochemical device in which an additive for ethylene production is used. [Figure 2] FIG. 1 is a diagram showing the relationship between the potential of the working electrode and the faradaic efficiency of each product. [Figure 3]FIG. 10 is a diagram showing the relationship between the potential of the working electrode and the partial current density of each product. [Figure 4] FIG. 1 is a diagram showing the relationship between additives and the Faraday efficiency of each product. [Figure 5] FIG. 1 is a graph showing the relationship between additives and ethylene selectivity. [Figure 6] FIG. 1 is a graph showing the relationship between additives and the faradaic efficiency of ethylene production. [Figure 7] FIG. 1 shows the relationship between additives and partial current density for ethylene production. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the present invention. The upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined from the numerical values ​​exemplified individually or as numerical ranges to form a suitable numerical range.

[0015] Additive for ethylene production The additive for ethylene production contains at least one substituted or unsubstituted 1,2,4-triazole compound represented by the following formula (1) or a tautomer thereof. The additive for ethylene production is used in a reaction for producing ethylene from a carbon source containing at least one of carbon monoxide and carbon dioxide, and can improve the selectivity of ethylene production.

[0016] [ka]

[0017] In formula (1), R 1represents a hydrogen atom, a halogen atom, an amino group which may have a substituent, a hydroxy group, a cyano group, a thiol group, an alkyl group which may have a substituent and has 1 to 10 carbon atoms, an alkoxy group which may have a substituent and has 1 to 10 carbon atoms, or an aryl group which may have a substituent and has 6 to 10 carbon atoms. The compound represented by formula (1) contained in the ethylene production additive may contain at least one of its tautomers.

[0018] R 1 The amino group represented by the formula (I) may have a substituent or may be unsubstituted. The substituent in the amino group may be a substituent formed from at least two atoms selected from the group consisting of hydrogen atoms, carbon atoms, nitrogen atoms, oxygen atoms, and sulfur atoms. The substituent may have a linear, branched, or cyclic structure, or a combination thereof.

[0019] When the substituent on the amino group is a group formed from hydrogen atoms and carbon atoms, the substituent can be an alkyl group. The alkyl group can have, for example, 1 to 10 carbon atoms. Specific examples of the alkyl group substituting the amino group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, a neo-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. The number of alkyl groups substituting the amino group can be one or two. When the number of alkyl groups substituting the amino group is two, the two alkyl groups can be the same or different.

[0020] When the substituent on the amino group is a group containing an atom other than a hydrogen atom and a carbon atom, examples of the substituent include an alkylamino group, a dialkylamino group, an amidino group, an amido group, a thioamide group, an acyl group such as an acetyl group, a methoxy group, an ethoxy group, a sulfamoyl group, an aziridinyl group, an azetinidyl group, a triazolyl group, an oxiranyl group, and an oxetanyl group.

[0021] R 1 The alkyl group represented by the formula (I) may be linear, branched, cyclic, or a combination thereof. The number of carbon atoms in the alkyl group may be, for example, 1 to 10. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, a neo-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.

[0022] R 1 The alkyl group represented by the formula (I) may have a substituent. Examples of the substituent include a halogen atom, an amino group which may have a substituent, a hydroxy group, an alkoxy group, a cyano group, a thiol group, an alkylthio group, an aziridinyl group, an azetinidyl group, a triazolyl group, an oxiranyl group, an oxetanyl group, a carboxyl group, and the like, and may be at least one selected from the group consisting of these. The alkyl group moieties of the amino group, alkoxy group, and alkylthio group which may have a substituent are as described above, and the same applies hereinafter. R 1 When the alkyl group represented by the formula (I) has a substituent, the number of substitutions in the alkyl group may be, for example, 1 to 5, and preferably 1 to 3. When the alkyl group has multiple substituents, the multiple substituents may be the same or different.

[0023] R 1 The alkyl group moiety in the alkoxy group represented by the formula (I) may be linear, branched, cyclic, or a combination thereof. The number of carbon atoms in the alkyl group may be preferably 1 to 10. Specific examples of the alkyl group moiety in the alkoxy group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, a neo-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.

[0024] R 1 The number of carbon atoms in the aryl group represented by the formula (I) may be, for example, 6 or 10, and preferably 6. Specific examples of the aryl group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0025] R 1 The aryl group represented by the formula (I) may have a substituent. Examples of the substituent include a halogen atom, an amino group which may have a substituent, a hydroxy group, a cyano group, a thiol group, an alkylthio group, an aziridinyl group, an azetinidyl group, a triazolyl group, an oxiranyl group, an oxetanyl group, a carboxyl group, and the like, and may be at least one selected from the group consisting of these. When the aryl group has a substituent, the number of substitutions in the aryl group may be, for example, 1 to 7, and preferably 1 to 5. When the aryl group has multiple substituents, the multiple substituents may be the same or different.

[0026] From the viewpoint of ethylene production efficiency, R 1 is preferably a hydrogen atom, an amino group (-NH), a monoalkylamino group having 1 to 10 carbon atoms, a dialkylamino group having an alkyl group having 1 to 10 carbon atoms, an alkylaminoalkyl group having 1 to 10 carbon atoms, or an aminoalkyl group having 1 to 10 carbon atoms, and more preferably a hydrogen atom, an amino group, a monoalkylamino group having 1 to 10 carbon atoms, or a dialkylamino group having an alkyl group having 1 to 10 carbon atoms.

[0027] The ethylene production additive may contain at least one compound represented by formula (1). The compound represented by formula (1) contained in the ethylene production additive may be one type alone or a mixture of two or more types. The content of the compound represented by formula (1) in the ethylene production additive may be, for example, 95% by mass or more, preferably 97% by mass or more, and may essentially consist of the compound represented by formula (1). Here, "substantially" means that unavoidable impurities are allowed, and specifically means that the content of compounds other than the compound represented by formula (1) is 5% by mass or less, preferably 3% by mass or less.

[0028] Additives for ethylene production may contain inorganic impurities. If the inorganic impurities include heavy metals with a carbon monoxide adsorption energy greater than that of copper, the metal impurities deposited on the copper catalyst may cause inactivation due to carbon monoxide adsorption, resulting in increased hydrogen generation and reduced ethylene selectivity. Furthermore, if the carbon monoxide adsorption capacity is smaller than that of copper, the amount of carbon monoxide, formic acid, etc. produced may increase.

[0029] The ethylene production additive is used in a reaction to produce ethylene from a carbon source containing at least one of carbon monoxide and carbon dioxide. The carbon source may contain at least one of carbon monoxide and carbon dioxide, and preferably at least carbon dioxide. The carbon source may further contain another carbon source other than carbon monoxide or carbon dioxide. Examples of other carbon sources include hydrocarbons such as methane remaining in the dry reforming process of natural gas (methane). Other examples include aldehydes, alcohols, synthetic fatty acids, and the like contained in gas recovered by oxosynthesis. The use of the ethylene production additive also makes it possible to use low-grade natural gas containing carbon dioxide as a carbon source. The carbon source may also be gaseous.

[0030] The reaction for producing ethylene from a carbon source using an ethylene-producing additive may include, for example, an electrolytic reduction reaction for producing ethylene from carbon dioxide by an electrochemical reaction. A copper electrode is known as an electrolytic reduction electrode (working electrode) that is selective for converting carbon dioxide to hydrocarbons. In an electrolytic reduction reaction using this copper electrode, the efficiency of ethylene production can be improved by adding an ethylene-producing additive to the electrolyte. The ethylene-producing additive can also be produced by hydrolysis or the like in the electrolyte system, as long as it does not inhibit the reaction.

[0031] Use of an ethylene production additive can improve the selectivity in the ethylene production reaction from a carbon source. Improved selectivity means an increase in the ethylene content in the product from the carbon source in the ethylene production reaction, which can be evaluated, for example, by the Faraday efficiency. Furthermore, the reaction activity in the ethylene production reaction from the carbon source can be improved. Improved reaction activity means an increase in the rate of the electrolytic reduction reaction, which can be evaluated, for example, by the current density in the electrolytic reaction. Furthermore, the additive can efficiently suppress oxidation corrosion of the copper electrode surface used in the electrolytic reduction electrode and the decrease in reaction activity associated with corrosion.

[0032] The reaction for producing ethylene from a carbon source in the presence of an ethylene-producing additive may include, for example, the following reaction. Positive electrode reaction: H2O → 1 / 2O2 + 2H + + 2e - Negative electrode reaction: (Intermediate) CO2+ 2H + + 2e - → CO + HO (Ethylene production reaction) 2CO2+ 12H + + 12e - → C2H4+ 4H2O (Side reactions: hydrogen, carbon) 2H + + 2e - → H2 CO2+ 4H + + 4e - → C + 2H2O (Side reaction: formic acid) CO2+ 2H + + 2e - → HCOOH (Side reactions: methane, methanol) CO2+ 8H + + 8e - → CH4+ 2H2O CO2+ 6H + + 6e - → CH3OH + HO (Side reaction: ethanol) 2CO2+ 12H + + 12e - → C2H5OH + 3H2O

[0033] The reaction of producing ethylene from a carbon source in the presence of an ethylene-producing additive can be carried out using an electrochemical device equipped with a working electrode and a counter electrode, using an electrolyte containing the ethylene-producing additive. The electrochemical device may have a configuration such as that shown in the schematic perspective view of FIG. 1.

[0034] 1 includes a working electrode chamber 22 equipped with a working electrode 10 and a reference electrode 14, a counter electrode chamber 24 equipped with a counter electrode 12, and a gas chamber 20. The working electrode chamber 22 and the counter electrode chamber 24 are separated by a diaphragm 32, and the gas chamber 20 and the working electrode chamber 22 are separated by a gas diffusion layer 30 equipped with a working electrode 10. An electrolyte containing an additive for ethylene production is supplied to the working electrode chamber 22 and the counter electrode chamber 24 from an electrolyte supply port 40, and recovered from an electrolyte recovery port 42.

[0035] The gas diffusion layer 30 has a structure in which a copper layer 52 is formed on a gas permeable layer 50, and the copper layer 52 functions as the working electrode 10. The copper layer 52 may be a layer containing only copper, or may be a layer containing copper and another metal as long as the effect of the electrolytic reduction reaction is not impaired. The counter electrode 12 may be, for example, a platinum electrode.

[0036] A carbon source containing carbon dioxide is supplied to the gas chamber 20 through a gas supply port 44, and the product is recovered through a gas discharge port 46. The carbon dioxide supplied to the gas chamber is reduced to ethylene on the working electrode and recovered in the gas chamber.

[0037] electrolyte The electrolytic solution contains the additive for ethylene production, an electrolyte, and a liquid medium. The electrolytic solution may contain a surfactant, if necessary. The electrolytic solution is used, for example, as an electrolytic solution in an electrolytic reduction reaction for producing ethylene from a carbon source containing at least one of carbon monoxide and carbon dioxide. By including the additive for ethylene production in the electrolytic solution, the efficiency of ethylene production from the carbon source can be improved.

[0038] The details of the additive for ethylene production contained in the electrolytic solution are as described above. The content of the additive for ethylene production in the electrolytic solution may be, for example, 1% by mass or more and 30% by mass or less, and preferably 5% by mass or more or 15% by mass or less.

[0039] The electrolyte may be a salt containing an alkali metal ion such as a sodium ion or potassium ion, or a cation such as an ammonium ion or guanidium ion. Examples of anions constituting the salt include hydroxide ions, bicarbonate ions, carbonate ions, nitrate ions, hydrogen sulfate ions, sulfate ions, dihydrogen phosphate ions, hydrogen phosphate ions, phosphate ions, formate ions, acetate ions, oxalate ions, tartrate ions, and citrate ions. Specific examples of the electrolyte include potassium bicarbonate, sodium bicarbonate, potassium carbonate, sodium carbonate, sodium sulfate, and potassium sulfate.

[0040] The content of the electrolyte in the electrolytic solution may be, for example, 0.1 mol / L or more and 10 mol / L or less, and preferably 0.5 mol / L or more or 2 mol / L or less. When the content of the electrolyte is equal to or less than the above upper limit, a decrease in the solubility of carbon dioxide is suppressed, and a decrease in ethylene selectivity is suppressed.

[0041] The liquid medium constituting the electrolytic solution may contain at least water as long as it can dissolve the ethylene-producing additive and the electrolyte. The liquid medium may further contain at least one water-soluble organic solvent in addition to water. Examples of the water-soluble organic solvent include alcohols such as methanol, carbonate esters such as ethylene carbonate, and glymes such as diethylene glycol. The water content in the liquid medium may be, for example, 50% by volume or more, preferably 90% by volume or more. Furthermore, the electrolytic solution may further contain at least one surfactant. There are no particular limitations on the surfactant as long as it can dissolve or disperse the ethylene-producing additive.

[0042] The pH of the electrolyte is not particularly limited, but may be, for example, 5.0 or more and 9.0 or less, and preferably 6.0 or more and 7.8 or less. The pH is measured at 25°C using a commonly used pH meter.

[0043] When the pH is equal to or higher than the lower limit and the proton concentration is relatively low, the side reaction of hydrogen generation tends to be easily suppressed, whereas when the pH is equal to or lower than the upper limit and the proton concentration is relatively high, carbon dioxide tends to be easily reduced.

[0044] The temperature of the electrolytic solution is not particularly limited, but may be, for example, a temperature during use of 0° C. or higher and 60° C. or lower, and preferably 10° C. or higher and 30° C. or lower. When the temperature is equal to or lower than the upper limit, the solubility of carbon dioxide in the electrolytic solution can be ensured, and the current efficiency tends to improve. [Example]

[0045] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0046] Example 1 Preparation of Electrolyte Solution E1 Potassium bicarbonate was dissolved in pure water to obtain a 1 mol / L aqueous potassium bicarbonate solution. 1,2,4-triazole, an additive for ethylene production, was dissolved in the obtained aqueous potassium bicarbonate solution to a concentration of 0.01 mass % to prepare an electrolyte solution E1.

[0047] Example 2 Preparation of Electrolyte Solution E2 An electrolyte solution E2 was prepared in the same manner as in Example 1, except that 3-amino-1,2,4-triazole (ATA) was used instead of 1,2,4-triazole.

[0048] Reference example 1 A 1 mol / L aqueous potassium bicarbonate solution containing no additives was used as the electrolyte C0.

[0049] Comparative Example 1 Preparation of Electrolyte Solution C1 An electrolyte solution C1 was prepared in the same manner as in Example 1, except that pyrrole was used instead of 1,2,4-triazole.

[0050] Comparative Example 2 Preparation of Electrolyte Solution C2 An electrolyte solution C2 was prepared in the same manner as in Example 1, except that imidazole was used instead of 1,2,4-triazole.

[0051] Comparative Example 3 Preparation of Electrolyte C3 An electrolyte solution C3 was prepared in the same manner as in Example 1, except that 1,2,3-triazole was used instead of 1,2,4-triazole.

[0052] Comparative Example 4 Preparation of Electrolyte Solution C4 An electrolyte solution C4 was prepared in the same manner as in Example 1, except that tetrazole was used instead of 1,2,4-triazole.

[0053] Comparative Example 5 Preparation of Electrolyte C5 An electrolyte solution C5 was prepared in the same manner as in Example 1, except that 3,5-diamino-1,2,4-triazole (DATA) was used instead of 1,2,4-triazole.

[0054] evaluation The evaluation was carried out using an electrochemical device as shown in Figure 1. A gas diffusion layer (MFK-A, manufactured by Mitsubishi Chemical Corporation) with 100 nm of copper deposited by sputtering was used as the working electrode. A platinum mesh was used as the counter electrode, and a reversible hydrogen electrode (RHE) was used as the reference electrode.

[0055] Rating 1 The gas chamber of the electrochemical device was filled with carbon dioxide, and the prepared electrolyte CO was flowed into the working and counter electrode chambers at a flow rate of 5 mL / min. A potentiogalvanostat (SP-50e; Biologic) was used to apply a predetermined potential to the working electrode, and the current density was evaluated. A 1 mL aliquot of the gas generated during electrolysis was then introduced into a gas chromatograph (GC2014; Shimadzu Corporation) to analyze the products. At the end of electrolysis under each condition, a 5 mL aliquot of the electrolyte was taken and the liquid-phase products were analyzed using a nuclear magnetic resonance spectrometer (ECZL-400; JEOL). The faradaic efficiency was estimated from the amount of product and the applied charge, and product selectivity was evaluated. The faradaic efficiency results for each product are shown in Table 1 and Figure 2. The partial current densities for each product are shown in Table 2 and Figure 3.

[0056] [Table 1]

[0057] The Faraday efficiency (FE) was calculated using the following formula. The potentials shown in Table 1 are the potentials (V) of the working electrode relative to the reference electrode (RHE). In the formula, n is the number of moles of the product, z is the electron equivalent involved in the electroreduction reaction, F is the Faraday constant, I is the current (A), and t is the time (seconds).

[0058]

number

[0059] As shown in Table 1 and Figure 2, an improvement in the faradaic efficiency of ethylene was observed when the potential of the working electrode relative to the reference electrode was set to -1.2 V or less. In particular, the faradaic efficiency of hydrogen was suppressed when the potential of the working electrode relative to the reference electrode was set to -1.5 V or less. Furthermore, the faradaic efficiencies of carbon monoxide and methane were almost constant, regardless of the potential of the working electrode relative to the reference electrode. These results show that current is used efficiently to generate ethylene when the potential of the working electrode relative to the reference electrode is set to -1.5 V or less.

[0060] [Table 2]

[0061] As shown in Table 2 and Figure 3, an increase in the partial current density of ethylene was observed when the potential of the working electrode relative to the reference electrode was set to -1.5 V or less. On the other hand, the partial current densities of hydrogen, carbon monoxide, and methane remained almost constant regardless of the potential of the working electrode relative to the reference electrode. These results show that the lower the potential applied to the working electrode, the greater the amount of ethylene produced per unit area.

[0062] Rating 2 The faradaic efficiency of each product was evaluated in the same manner as in Evaluation 1, except that the electrolyte solutions used were electrolyte solution E1 containing 1,2,4-triazole, electrolyte solution C2 containing imidazole, and electrolyte solution C0, which was a 1 mol / L aqueous potassium bicarbonate solution. The results are shown in Table 3 and Figure 4.

[0063] [Table 3]

[0064] As shown in Table 3 and Figure 4, adding imidazole to the electrolyte reduces the faradaic efficiency of ethylene and the faradaic efficiency of the C2 product, regardless of the potential of the working electrode relative to the reference electrode. On the other hand, adding 1,2,4-triazole to the electrolyte improves or nearly equals the faradaic efficiency of the C2 product, regardless of the potential of the working electrode relative to the reference electrode. These results suggest that imidazole is not an effective additive for ethylene production, but 1,2,4-triazole is.

[0065] Rating 3 The faradaic efficiency of each product was evaluated in the same manner as in Evaluation 1, except that the electrolytes used were electrolyte solution E1 containing 1,2,4-triazole, electrolyte solution C1 containing pyrrole, electrolyte solution C2 containing imidazole, electrolyte solution C3 containing 1,2,3-triazole, electrolyte solution C4 containing tetrazole, and electrolyte solution C0, a 1 mol / L aqueous potassium bicarbonate solution. The faradaic efficiency of ethylene was then divided by the sum of the faradaic efficiency of methane and the faradaic efficiency of carbon monoxide to calculate the ethylene selectivity. The results are shown in Table 4 and Figure 5.

[0066] [Table 4]

[0067] As shown in Table 4 and Figure 5, 1,2,4-triazole contributes to improving ethylene selectivity regardless of the potential of the working electrode relative to the reference electrode. On the other hand, pyrrole and tetrazole have almost no effect on improving ethylene selectivity regardless of the potential of the working electrode relative to the reference electrode. 1,2,3-triazole contributes to improving ethylene selectivity only when the potential of the working electrode relative to the reference electrode is set to -1.2 V, but has no effect on improving ethylene selectivity when the potential of the working electrode relative to the reference electrode is set to -1.5 V or less. Imidazole reduces ethylene selectivity regardless of the potential of the working electrode relative to the reference electrode. These results suggest that 1,2,4-triazole is the compound that contributes to improving ethylene selectivity.

[0068] Rating 4 The faradaic efficiency and partial current density of ethylene were evaluated in the same manner as in Evaluation 1, except that the electrolytes used were electrolyte solution E1 containing 1,2,4-triazole, electrolyte solution E2 containing 3-amino-1,2,4-triazole, electrolyte solution C5 containing 3,5-diamino-1,2,4-triazole, and electrolyte solution C0, a 1 mol / L aqueous potassium bicarbonate solution, and the potential of the working electrode was set to -2.1 V relative to the reference electrode. The results are shown in Table 5 and Figure 6.

[0069] [Table 5]

[0070] As shown in Table 5 and Figure 6, the use of 3-amino-1,2,4-triazole significantly improves the faradaic efficiency of ethylene compared to 1,2,4-triazole. On the other hand, the use of 3,5-diamino-1,2,4-triazole reduces the faradaic efficiency of ethylene. Furthermore, the use of 3-amino-1,2,4-triazole results in the greatest improvement in the partial current density of ethylene. On the other hand, the use of 1,2,4-triazole and 3,5-diamino-1,2,4-triazole results in a slight decrease in the partial current density of ethylene compared to the blank. These results indicate that 1,2,4-triazole and 3-amino-1,2,4-triazole are effective ethylene production catalysts. Furthermore, the use of 3-amino-1,2,4-triazole increases the amount of ethylene produced per unit area.

[0071] Rating 5 The electrolytes used were electrolyte solution E1 containing 1,2,4-triazole, electrolyte solution E2 containing 3-amino-1,2,4-triazole, electrolyte solution C5 containing 3,5-diamino-1,2,4-triazole, and electrolyte solution C0, which was a 1 mol / L aqueous potassium bicarbonate solution, and the effects on the working electrode were evaluated as follows.

[0072] The gas chamber of the electrochemical device was filled with carbon dioxide, and each electrolyte was flowed into the working electrode chamber and the counter electrode chamber at a flow rate of 5 mL / min. A voltage of -2.1 V was applied to the working electrode relative to the reference electrode using a potentiogalvanostat (SP-50e; Biologic, Inc.) for 0.5 hours, after which the working electrode was removed. The surface of the removed working electrode was visually observed and evaluated according to the following criteria. The results are shown in Table 6.

[0073] Evaluation criteria A: No discoloration was observed on the working electrode. B: Only the end of the working electrode was slightly discolored. C: The surface of the working electrode was partially oxidized and discolored. D: The entire surface of the working electrode was oxidized and discolored.

[0074] [Table 6]

[0075] As shown in Table 6, the triazole compounds of the examples exhibited an effect of inhibiting oxidation of the working electrode. By inhibiting oxidation corrosion of the working electrode, it is expected that the life of the working electrode will be extended. [Explanation of symbols]

[0076] 10 Working electrode 12 Opposites 14 Reference electrode 22 Working electrode chamber 30 Gas diffusion layer 100 Electrochemical Device

Claims

1. An additive for producing ethylene from a carbon source containing at least one of carbon monoxide and carbon dioxide, comprising a compound represented by the following formula (1): An additive for ethylene production that is added to an electrolyte used in the electrolytic reduction reaction of the carbon source. 【Chemistry 1】 (In general formula (1), R １ represents a hydrogen atom or an amino group.

2. An electrolytic solution comprising the additive for ethylene production according to claim 1, an electrolyte, and a liquid medium.

3. An electrolyte solution as described in claim 2, wherein the liquid medium contains at least water.

4. An electrolyte solution as described in claim 2, wherein the content of the ethylene-generating additive is 1 mass % or more and 30 mass % or less.

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