WO2018062952A1 - Complex process for reducing carbon dioxide and producing formic acid and potassium sulfate, and apparatus for said complex process - Google Patents

Abstract

The present application relates to a complex process for reducing carbon dioxide and producing formic acid and potassium sulfate and to an apparatus for said complex process.

Description

Combined process of carbon dioxide reduction and formic acid and potassium sulfate production, and apparatus for the combined process

The present application relates to a combined process of carbon dioxide reduction and formic acid and potassium sulfate production, and to an apparatus for the combined process.

Formic acid can be used for leather treatment, rubber coagulant, dyeing aid, hair dye, leather tanning, medicine, epoxy plasticizer, plating, disinfectant, fragrance, electroplating, dyeing and textile industry, organic raw materials, and inorganic / organic compound manufacturing. It is a compound used in the field. It is used 20,000 tons annually in Korea, and is mainly used in the process of producing leather products, and is produced in BASF, Kemira, and China, and consumes about 700,000 tons annually.

Conventional formic acid production methods include sodium formate technology, methyl formate hydrolysis technology, and polyhydric alcohol process by-products developed by BASF, Germany. Many of the existing formic acid production processes are hydrolysed by synthesizing methyl formate from methanol and carbon monoxide as well as complex processes, and are synthesized under high temperature and high pressure conditions of 80 ℃ and 40 atm. There is a problem that the process must be high and continuous. In addition, since there is a need for the continuous supply of harmful carbon monoxide, a large amount of water is required for hydrolysis has a problem of wastewater treatment after use.

On the other hand, potassium sulfate can be used as a potassium fertilizer in crops in which chlorinated fertilizer cannot be used, and can be combined with various fertilizers because it has almost no smell. When the potassium sulfate is used as a fertilizer, the fertilizer effect appears quickly, and is known as a basic fertilizer together with ammonium sulfate and phosphoric acid peroxide. In addition, the potassium sulfate can be used as a raw material of potassium alum, potassium bromide or pharmaceuticals for use other than the fertilizer, and is used in the world more than 4 million tons per year.

To the production process, the existing sulfate, potassium sulfate was added to the potassium chloride is heated at high temperature to determine a metathesis from hydrochloric acid and a method of creating a potassium sulfate, Kai nitro, or key ISERE seat aqueous solution was added to potassium chloride to (MgSO ₄ and H ₂ O) The method of making it precipitate, and the method of adding sulfuric acid to aqueous potassium chloride solution, making potassium hydrogen sulfate, crystallizing by adding equivalent potassium chloride, and recrystallizing in aqueous solution, etc. are mentioned. About 50% of the process for producing potassium sulfate is a method of adding sulfuric acid to potassium chloride and heating at high temperature (600 ° C. to 700 ° C.), which is a Mannheim process for producing potassium sulfate. Since the Mannheim process uses a lot of energy, the production cost is high, and only a small process is possible.

The present inventors electrochemically reduce carbon dioxide to obtain a high concentration of formic acid (potassium formate, HCOOK), and then, when the formic acid is converted to formic acid, the separation and acidification process is performed effectively, high purity formic acid and potassium sulfate It was found that it can be obtained at the same time. The new process is environmentally friendly and consumes less energy than existing processes for commercially producing formic acid. In this regard, US patent US 08562811 discloses a process for producing formic acid as an electrochemical process of carbon dioxide.

The present application provides a combined process of carbon dioxide reduction and formic acid and potassium sulfate production, and an apparatus for the combined process.

However, the problem to be solved by the present invention is not limited to the above-mentioned problem, another task that is not mentioned will be clearly understood by those skilled in the art from the following description.

A first aspect of the present application, the first reactor for producing a formate by electrochemical reduction of carbon dioxide in an electrolyte containing potassium sulfate; A concentrator connected to the first reactor and concentrating an electrolyte solution containing the formate and potassium sulfate prepared in the first reactor to a solid containing formate and potassium sulfate; A second reactor connected to the concentrator, for adding sulfuric acid to the solid containing formate and potassium sulfate obtained in the concentrator to prepare a solution containing formic acid and potassium sulfate solids; And a separator connected to the second reactor and including a separator for separating the solution containing the formic acid and the potassium sulfate solid prepared in the second reactor into a formic acid-containing solution and potassium sulfate solid, respectively. And an apparatus for a complex process of preparing potassium sulfate.

According to a second aspect of the present invention, a formate is obtained by electrochemical reduction of carbon dioxide in an electrolyte solution containing potassium sulfate in a first reactor, and the electrolyte solution including the formate and potassium sulfate obtained from the first reactor is obtained. Transferred to a concentrator, concentrated to a solid containing formate and potassium sulfate, and the solid containing formate and potassium sulfate separated in the concentrator was transferred into a second reactor to add sulfuric acid to add formic acid and potassium sulfate solid Obtaining a solution comprising, and transferring the solution comprising the formic acid and potassium sulfate solids obtained in the second reactor to a separator to separate the formic acid-containing solution and the potassium sulfate solid, respectively; Provided is a complex process for preparing formic acid and potassium sulfate.

According to one embodiment of the present invention, a complex process of producing formate by reduction of carbon dioxide, which is a greenhouse gas, and converting the formate into formic acid and potassium sulfate, promotes reduction of carbon dioxide, which is a greenhouse gas, and proceeds in an aqueous solution. Because of the process, it is environmentally friendly and can reduce energy costs compared to the energy costs of the formic acid production process and the potassium sulfate production process.

According to one embodiment of the present application, the conventional formic acid manufacturing process is a high temperature process using CO and H ₂ generated on the basis of petrochemical, whereas the complex process of the present application is an environmentally friendly and greenhouse gas gas at room temperature using CO ₂ It is a process to reduce.

Since the complex process is performed in two steps, the reaction may be terminated in one step to obtain only formate, and the reaction may be performed up to two steps to obtain formic acid and potassium sulfate. According to one embodiment of the present application, the obtained formic acid and potassium sulfate are very useful because of their high purity.

1 is a schematic view showing a complex process of carbon dioxide reduction and formic acid and potassium sulfate production in one embodiment of the present application.

Figure 2, in one embodiment of the present application, is a process chart showing a combined process of carbon dioxide reduction and formic acid and potassium sulfate production.

3 is, in one embodiment of the present application, a first reactor system for electrochemical CO ₂ conversion.

4 is a photograph showing a metal hydroxide supply chamber in a first reactor in one embodiment of the present application.

5 is K ₂ SO ₄ in the CO ₂ conversion of the first reactor, in one embodiment of the present application The material balance of the system.

FIG. 6 shows electrolysis of CO ₂ by amalgam coated foamed copper electrodes in a first reactor with 0.5 MK ₂ SO ₄ , in one embodiment of the present disclosure.

FIG. 7 shows long-term electrolysis of CO ₂ in a first reactor (0.5 MK ₂ SO ₄ ) with a pH feedback system, in one embodiment of the present disclosure.

8 is a graph showing a result of dissolving formic acid in a solvent using formic acid as a solvent and performing acidification with sulfuric acid in one example of the present application.

FIG. 9 illustrates the formic acid production process and energy consumption of each of Examples and Comparative Examples in Examples and Comparative Examples.

10 shows a process for preparing potassium sulfate and the process conditions of each of Examples and Comparative Examples of the present application.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present disclosure. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted for simplicity of explanation, and like reference numerals designate like parts throughout the specification.

Throughout this specification, when a portion is "connected" to another portion, this includes not only "directly connected" but also "electrically connected" with another element in between. do.

Throughout this specification, when a member is located “on” another member, this includes not only when one member is in contact with another member but also when another member exists between the two members.

Throughout this specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding the other components unless specifically stated otherwise. As used throughout this specification, the terms "about", "substantially" and the like are used at, or in the sense of, numerical values when a manufacturing and material tolerance inherent in the stated meanings is indicated, Accurate or absolute figures are used to assist in the prevention of unfair use by unscrupulous infringers. As used throughout this specification, the term "step to" or "step of" does not mean "step for."

Throughout this specification, the term “combination of these” included in the expression of the makushi form means one or more mixtures or combinations selected from the group consisting of the constituents described in the expression of the makushi form, wherein the constituents It means to include one or more selected from the group consisting of.

A first aspect of the present application, the first reactor for producing a formate by electrochemical reduction of carbon dioxide in an electrolyte containing potassium sulfate; A concentrator connected to the first reactor and concentrating an electrolyte solution containing the formate and potassium sulfate prepared in the first reactor to a solid containing formate and potassium sulfate; A second reactor connected to the concentrator, for adding sulfuric acid to the solid containing formate and potassium sulfate obtained in the concentrator to prepare a solution containing formic acid and potassium sulfate solids; And a separator connected to the second reactor, the separator comprising separating the solution containing the formic acid and the potassium sulfate solid prepared in the second reactor into a formic acid-containing solution and potassium sulfate solid, respectively. Provided is a device for a complex process of preparing potassium.

According to a second aspect of the present invention, a formate is obtained by electrochemical reduction of carbon dioxide in an electrolyte solution containing potassium sulfate in a first reactor, and the electrolyte solution including the formate and potassium sulfate obtained from the first reactor is obtained. Transferred to a concentrator and concentrated to separate the formate and potassium sulfate solids respectively, and the solid containing formate and potassium sulfate obtained in the concentrator was transferred into a second reactor to add sulfuric acid to include formic acid and potassium sulfate solids. Carbon dioxide reduction and formic acid, comprising separating the solution comprising the formic acid and potassium sulfate solids obtained in the second reactor into a separator and separating the formic acid-containing solution and the potassium sulfate solid, respectively; Provided is a complex process of preparing potassium sulfate.

In one embodiment of the present application, with reference to Figures 1 and 2 will be described for the combined process and the combined process of the carbon dioxide reduction and formic acid and potassium sulfate production, first the electricity of the carbon dioxide in the first reactor (100) High concentration of formate can be obtained through chemical reduction reaction. The first reactor 100 will be described in detail. The first reactor includes an electrolyte containing potassium sulfate, a cathode, an anode, and a membrane separating the cathode and the anode. The first reactor system is connected to the reduction electrode unit to reduce the electrode portion injection line 160 for supplying carbon dioxide and a solution of the reduction electrode portion to the reduction electrode portion and the reduction to collect the materials supplied to the reduction electrode portion A first chamber 150 connected to an electrode collection line 170, an anode electrode injection line 210 connected to the anode electrode to supply an anode electrode solution to the anode electrode, and an anode electrode And a second chamber 200 connected to the anode portion collection line 220 for collecting the prepared solution. In the first reactor 100, an electrolytic solution containing the formate and potassium sulfate is obtained through an electrochemical reduction reaction of carbon dioxide, and the electrolyte solution including the formate and potassium sulfate is obtained by using a concentrator injection line 250. According to the concentrator 300. The electrolytic solution containing the formate and potassium sulfate is concentrated in the concentrator 300 to obtain a solid containing potassium formate and potassium sulfate, and the solid containing the formate and potassium sulfate is in the second reactor injection line ( Along the 320 is injected into the second reactor 350. The second reactor (350) system includes a third chamber (400) for injecting sulfuric acid into the second reactor (350) by sulfuric acid injection line (410), the formate injected from the concentrator (300) And a solid containing potassium sulfate may react with the sulfuric acid in the second reactor 350 to obtain a solution containing formic acid and potassium sulfate solids. The solution containing formic acid and potassium sulfate is injected into the separator 450 along the separator injection line 420, and the solution containing the formic acid and potassium sulfate solid in the separator 450 contains a formic acid-containing solution and potassium sulfate. Each separated into solids, and the separated potassium sulfate solids are collected along the second potassium sulfate collection line 460, and the separated formic acid-containing solution is collected along the formic acid collection line 470, respectively.

In one embodiment of the present application, the concentration may be performed by distillation, but is not limited thereto.

In one embodiment of the present application, the purity of each of the formic acid and the potassium sulfate may be at least about 85% high purity independently of each other. For example, the purity of each of the formic acid and the potassium sulfate is independently about 85% to about 99.9%, about 86% to about 99.9%, about 87% to about 99.9%, about 88% to about 99.9%, about 89 % To about 99.9%, about 90% to about 99.9%, about 91% to about 99.9%, about 92% to about 99.9%, about 93% to about 99.9%, about 94% to about 99.9%, about 95% to About 99.9%, about 96% to about 99.9%, about 97% to about 99.9%, about 98% to about 99.9%, about 99% to about 99.9%, about 99.1% to about 99.9%, about 99.2% to about 99.9 %, About 99.3% to about 99.9%, about 99.4% to about 99.9%, about 99.5% to about 99.9%, about 99.6% to about 99.9%, about 99.7% to about 99.9%, about 99.8% to about 99.9%, About 85% to about 99.8%, about 85% to about 99.7%, about 85% to about 99.6%, about 85% to about 99.5%, about 85% to about 99.4%, about 85% to about 99.3%, about 85 % To about 99.2%, about 85% to about 99.1%, about 85% to about 99%, about 85% to about 98%, about 85% to about 97%, about 85% to About 96%, about 85% to about 95%, about 85% to about 94%, about 85% to about 93%, about 85% to about 92%, about 85% to about 91%, about 85% to about 90 %, About 85% to about 89%, about 85% to about 88%, about 85% to about 87%, or about 85% to about 86%.

In one embodiment of the present application, the first reactor is an electrochemical reduction reactor of carbon dioxide comprising an electrolyte solution containing potassium sulfate, an anode portion and a reducing electrode portion, supplying carbon dioxide to the cathode portion, the anode A metal hydroxide is continuously supplied to the part, and a voltage or a current is applied to the cathode and the anode to reduce the carbon dioxide so that the formate is continuously obtained.

In one embodiment of the present application, the electrolytic solution included in the cathode electrode solution and the anode electrode solution comprises a selected from the group consisting of K ₂ SO ₄ , KHCO ₃ , KCl, KOH, and combinations thereof It may be, but is not limited thereto. In one embodiment of the present application, when KHCO ₃ is used as the electrolyte, KCl may be used as an auxiliary electrolyte to increase conductivity, but is not limited thereto. For example, when KHCO ₃ and KCl are used as the electrolyte, carbon dioxide can be converted for a long time with stable current efficiency. However, when electrolysis is performed for a long time, Cl ^- ions are transferred to the anode, and chlorine (Cl ₂ ) is formed. May occur. The generation of chlorine may cause problems such as metal corrosion or tube melting.

In one embodiment of the present application, when using only KHCO ₃ as the electrolyte, the efficiency may be reduced by about 10% because the conductivity is reduced. In one embodiment of the present application, when using K ₂ SO ₄ as the electrolyte, the efficiency is increased by about 5% to about 10% than when using KHCO ₃ and KCl as the electrolyte, since chlorine does not occur, corrosion Problems can be solved. However, when K ₂ SO ₄ is used to obtain a formate of about 0.5 M or more, the K ₂ SO ₄ may precipitate. Because of this, K ₂ SO ₄ is precipitated inside the glass frit to supply the CO ₂ gas, CO ₂ is not properly supplied or the solution may not circulate due to the crystal. In one embodiment of the present application, by using K ₂ SO ₄ of 0.5 M or less can solve the problem of precipitation of K ₂ SO ₄ , but is not limited thereto.

In one embodiment of the present application, the metal hydroxide may include a hydroxide of an alkali metal, but is not limited thereto.

In one embodiment of the present disclosure, the metal hydroxide may include, but is not limited to, one selected from the group consisting of KOH, NaOH, LiOH, and combinations thereof.

In one embodiment of the present application, the concentration of the formate may be about 5% or more, but is not limited thereto. For example, the concentration of the formate is about 5% to about 30%, about 10% to about 30%, about 15% to about 30%, about 20% to about 30%, about 25% to about 30%, about 5% to about 25%, about 5% to about 20%, about 5% to about 15%, or about 5% to about 10%, but is not limited thereto.

In one embodiment of the present application, by continuously supplying the metal hydroxide to the anode portion, a high concentration of formate of about 0.5 M or more may be continuously obtained by reduction of carbon dioxide, but is not limited thereto.

In one embodiment of the present application, when formate is produced at a certain concentration or more during prolonged electrolysis, the voltage may change rapidly, which may be due to the sharp change in the pH of the electrode part solution. The sharp change in pH is due to the breakage of the buffer solution of the cathode solution as the hydrogen ions generated in the anode solution are excessively supplied to the cathode solution through the separator. Therefore, when the metal hydroxide is continuously added to the anode portion solution, neutralizing the generated hydrogen ions to maintain the pH and voltage of the anode portion solution to adjust the amount of excess hydrogen ion For a long time, electrolysis can be made possible. In addition, as the metal hydroxide is continuously supplied, the metal cation of the metal hydroxide is also continuously supplied. As a result, a high concentration of formate of about 0.5 M or more can be obtained continuously for a long time.

In one embodiment of the present application, the current density by applying a voltage to the cathode electrode portion and the anode portion may be about 350 mA / cm ² or less, but is not limited thereto. For example, the current density is about 2 mA / cm ² to about 350 mA / cm ² , about 2 mA / cm ² to about 300 mA / cm ² , about 2 mA / cm ² to about 250 mA / cm ² , about 2 mA / cm ² to about 200 mA / cm ² , about 2 mA / cm ² to about 150 mA / cm ² , about 2 mA / cm ² to about 100 mA / cm ² , about 2 mA / cm ² to about 50 mA / cm ² , about 2 mA / cm ² to about 10 mA / cm ² , about 10 mA / cm ² to about 350 mA / cm ² , about 50 mA / cm ² to about 350 mA / cm ² , about 100 mA / cm ² to about 350 mA / cm ² , about 150 mA / cm ² to about 350 mA / cm ² , about 200 mA / cm ² to about 350 mA / cm ² , about 250 mA / cm ² to about 350 mA / cm ² , or about 300 mA / cm ² to about 350 mA / cm ² , but is not limited thereto.

In one embodiment of the present application, the cathode portion may include tin, mercury, lead, indium, or amalgam electrode, but is not limited thereto.

In one embodiment of the present application, the amalgam electrode is a mixture, composite, or alloy containing Hg on the surface of the base electrode and a metal selected from the group consisting of Ag, In, Sn, Pb, Cu, and combinations thereof It may be to include that formed, but is not limited thereto.

In one embodiment of the present application, the amalgam electrode may be to include a dental amalgam, but is not limited thereto. The dental amalgam can provide a safe amalgam electrode that can ignore the toxicity caused by mercury.

In one embodiment of the present disclosure, the amalgam electrode has about 35 parts by weight to about 55 parts by weight of Hg, about 14 parts by weight to about 34 parts by weight of Ag, about 7 parts by weight to about 17 parts by weight of Sn, and about 4 parts by weight To about 24 parts by weight of Cu, but is not limited thereto.

In one embodiment of the present application, the base electrode may be one having a porous, plate-like, rod-shaped, or foam type, but is not limited thereto. For example, the substrate electrode having porosity may include a granular assembly, a porous electrode by surface treatment, or a mesh metal electrode, but is not limited thereto.

In one embodiment of the present disclosure, the base electrode may include, but is not limited to, a group selected from the group consisting of copper, tin, nickel, carbon, free carbon, silver, gold, and combinations thereof.

In one embodiment of the present application, the amalgam electrode may be formed using an amalgamator or by electroplating, but is not limited thereto.

In one embodiment of the present disclosure, the amount of sulfuric acid added to the formate-containing solution may be about 40 parts by weight to about 75 parts by weight based on 100 parts by weight of the formate-containing solution, but is not limited thereto. . For example, the amount of sulfuric acid added to the formate-containing solution is about 40 parts by weight to about 75 parts by weight, about 45 parts by weight to about 75 parts by weight, about 100 parts by weight of the formate-containing solution. 50 parts by weight to about 75 parts by weight, about 55 parts by weight to about 75 parts by weight, about 60 parts to about 75 parts by weight, about 65 parts by weight to about 75 parts by weight, about 70 parts by weight to about 75 parts by weight, about 40 parts by weight to about 70 parts by weight, about 40 parts by weight to about 65 parts by weight, about 40 parts by weight to about 60 parts by weight, about 40 parts by weight to about 55 parts by weight, about 40 parts by weight to about 50 parts by weight, or About 40 parts by weight to about 45 parts by weight, but is not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are only provided to help understanding of the present application, and the contents of the present application are not limited to the following Examples.

[ Example ]

<High concentration of carbon dioxide using electrochemical reduction method and apparatus Formate  Manufacture

Referring to FIGS. 1 and 2 showing the combined process of carbon dioxide reduction and formic acid and potassium sulfate production, first, electrochemical conversion of carbon dioxide using a flow cell (first reactor) for the production of high concentration of formate. The experiment was performed. Amalgam coated rod electrode, amalgam coated foam electrode, or amalgam coated plate electrode were used as working electrodes, and a titanium mesh DSA electrode coated with IrOx was used as a counter electrode. A constant current was applied and the voltage at both ends was measured. The cathode electrode solution was supplied to the cathode electrode portion, the anode electrode solution was supplied to the anode electrode portion, and the shape of the carbon dioxide conversion system (first reactor system) used is shown in FIG. 3.

In general, there is a problem that the efficiency is lowered because the pH of the anode and the cathode portion is continuously changed during electrolysis for a long time. In order to solve the above problems, in this embodiment, 5 M potassium hydroxide (KOH) solution is continuously added to the anode portion (FIG. 4) to maintain a constant pH of the anode portion electrolyte. It was confirmed that the pH is constantly maintained. When potassium sulfate was used as the electrolyte, the ion balance form of the electrolyte in the carbon dioxide conversion system is shown in FIG. 5. Experiments using the potassium sulfate electrolyte showed an efficiency of 80% to 90% (Fig. 6). If you use a too low concentration of K ₂ SO _4, because the concentration of ions decreases the conductivity increases, the cell voltage becomes lower relatively, as well as wake appeared phenomenon that efficiency is low, and a solution of K ⁺ ion concentration is low, ions are both It was also confirmed that the pH and voltage suddenly changed when consumed.

For electrolysis, constant potentiometers (EG & G, 273A) and constant current devices (KS RnD, CO ₂ _ 10A) were used. In this case, a working electrode was used as a foam electrode (3 cm x 3 cm, 0.5 cm thick), and the electrolyte volume was used in a variety of 100 mL to 1,000 mL, but mainly 100 mL to 200 mL. The electrolyte of the anode portion and the electrolyte of the cathode portion were separated and separated by a Nafion ^® 117 membrane. Ultra high purity carbon dioxide (purity 99.99%) was continuously supplied to the electrolyte of the cathode by using glass-frit, and ultra high purity argon (purity 99.99%) was supplied to the electrolyte of the anode, or gas was supplied. Electrolysis was performed without injection. The pump for circulating the solution used a diaphragm pump and a peristaltic pump. The product, formate, was quantitatively analyzed by liquid chromatography.

<Preparation of high purity formic acid and potassium sulfate>

Since the high concentration formate (1.6 M) obtained by electrochemical reduction of carbon dioxide using potassium sulfate as an electrolyte in Example 1 is dissolved in the potassium sulfate (0.2 M) solution, the formate is concentrated by concentration. Separated. In the potassium sulfate solution, the solubility of the formate is 3,400 g / L, the solubility of the potassium sulfate is 120 g / L, and when a high concentration of formate is dissolved in the potassium sulfate solution as in Example 1, Since the solubility of the potassium sulfate was further reduced, the formate could be easily separated into a liquid and the potassium sulfate could be separated into a solid by concentration. In the actual process, it was designed to use a multi-efficiency evaporator, but in this example, the solid formate was obtained by evaporating the potassium sulfate solution in which the high concentration of formate was dissolved in order to conduct experiments at the laboratory level. Thereafter, the formate was dissolved in formic acid, and sulfuric acid was added in an equivalent ratio to prepare a mixed solution containing formic acid and potassium sulfate. The reaction formula of the formate and sulfuric acid can be represented as in Scheme 1 below.

<Scheme 1>

2HCOOK + H ₂ SO ₄ 2HCOOH + K ₂ SO ₄

For the acid treatment experiment, Metrohm's 888 series titration was used, and sulfuric acid was used as a 95% purity solution of trielectric chemistry. 8 is a graph showing the results of the acidification reaction with sulfuric acid by dissolving formate in the solvent using formic acid as a solvent. As shown in the graph of FIG. 8, it was confirmed that the reaction proceeded stably. The mixed solution including the formic acid and potassium sulfate obtained through the reaction was distilled to separate the potassium sulfate as a solid and the formic acid as a liquid. The obtained formic acid was 98%, the potassium sulfate was obtained as a purity of 97%, respectively, the result requested by the Korea Institute of Chemical Convergence Testing in order to confirm the purity of the formic acid (purity: 98.2 %) Could be obtained. In addition, the purity of the potassium sulfate was requested by the Korea Chemical Research Institute Chemical Analysis Center to obtain the results shown in Table 2. The analysis of Table 2 was performed using Metrohm Ion Chromatograph C, and the analytical sample 1 contained 97.92% SO ₄ ^2- in terms of SO ₄ ^2- theoretical content of 55.17% in 100% K ₂ SO ₄ . , Sample 2 was confirmed to contain 97.86% SO ₄ ^2- .

Test Items	unit	Sample classification	Result	Test Methods
HCOOH	%	-	98.2	KS M 8260: 2015

Analysis item / sample name	HCOO - Content (%, w / w)	SO 4 2- content (%, w / w)
K 2 SO 4 Sample 1-1	-	52.41
K 2 SO 4 Sample 1-2	-	52.17
K 2 SO 4 Sample 1-3	-	57.49
K 2 SO 4 Sample 1 Average	-	54.02
K 2 SO 4 Sample 2-1	3.97	58.3
K 2 SO 4 Sample 2-2	2.85	54.24
K 2 SO 4 Sample 2-3	3.14	49.42
K 2 SO 4 Sample 2 Average	3.32	53.99

Increasing Current Density Using Electrodes

Electrolysis at a current density of 10 mAcm ^-2 using a rod-shaped amalgam electrode comprising 45% mercury, 24% tin, 17% silver, and 14% copper resulted in about -1.9 V (vs. Ag / AgCl) was maintained at a voltage of 70% or more for 10 hours or more. As a result, it was confirmed that the electrolysis is stably possible with the amalgam electrode, and the electrolysis was performed at a constant voltage of about -1.9 V using an amalgam coated foam electrode, indicating that the efficiency was about 80% over 10 hours. In the case of amalgam-coated foam electrodes, electrolysis proceeded at a current density of 30 mA · cm ⁻² , and it was confirmed that electrolysis was possible at a higher current density than that of the rod type.

As a method for increasing the current density, it was confirmed whether the current density can be increased by increasing the thickness of the amalgam-coated foam electrode having the same apparent area. As a result, the amalgam electrode coated on the 5 mm thick foam base electrode has a current density of 100 mAcm ^{-2 or} higher, and the amalgam electrode coated on the 10 mm thick foam base electrode 150 mA cm ^-2. As described above, and in the case of the amalgam electrode coated on the 20 mm-thick foam-type base electrode, the current efficiency was decreased when 200 mA · cm ^{−2 or} more. The current density until such a rapid decrease in efficiency was defined as the 'limiting current density'. As a result of the experiment, it was confirmed that it is possible to increase the current density by increasing the electrode thickness, but it was observed that the increase amount gradually decreased without linearly increasing the current density. This confirms that there is a limit to increasing the current density by simply increasing the thickness.

As another method to increase the current density, it was confirmed that the current density was increased by increasing the porosity of the amalgam-coated foam electrode having the same thickness and apparent area to increase the actual surface area. Experimental results For the electrode 20 ppi (pores per inch) previously used to increase the current density more than 100 mA · cm ^-2, while a phenomenon of decreasing the efficiency appeared, and 30 ppi for electrode is 350 mA · cm ^- When increased to ² or more, it was confirmed that the efficiency decreased. For this reason, it was confirmed that as the porosity increases, the surface becomes dense and the limit current density of the electrode can be increased by increasing the actual surface area in the same apparent area.

<High concentration Formate  Get>

Electrochemical reduction of carbon dioxide was carried out using the experimental method and apparatus presented in this example. In addition, the effect of maintaining the pH of the anode portion and the formation of high concentration of formate in the cathode portion by continuously adding potassium hydroxide (KOH) to the anode portion was confirmed.

As a result, when KOH was not continuously added to the anode under the same conditions, the voltage and pH changed drastically after 5 hours and the conversion efficiency from the cathode to the formate decreased to 40% after 8 hours. In the case where KOH was continuously added to the electrode, the voltage and pH were kept constant even after the electrolysis over 10 hours, and the conversion efficiency to the formate in the reduction electrode was also maintained without falling.

FIG. 7 is a graph obtained by prolonged electrolysis by continuously adding KOH to an anode part in the present embodiment. When KOH was continuously supplied to the anode for 34 hours and then electrolyzed for more than 34 hours, the pH and potential remained stable, and it was confirmed that more than 1 M of formate was produced with a current efficiency of 80% or more at the cathode. When the electrolysis was performed for a longer period, it was confirmed that the current efficiency was maintained at 80% or more even for about 2 M of the formate.

<Comparison of energy consumption between the existing formic acid production process and the new complex process of the present application>

In order to compare the energy consumption between the conventional formic acid production process and the new complex process of the present application (FIG. 9), energy consumption according to each unit process was estimated to convert the energy reduction amount according to the existing formic acid production process and the present embodiment. In the case of the existing process, the amount of energy used in the process was calculated using the Swiss EcoInvent LCI DB (http://www.ecoinvent.org), and the carbon monoxide to prepare methyl formate was generated from crude oil. It was calculated based on the production from heavy oil (Ecoinvent), and the methanol generated during MF hydrolysis was calculated assuming 100% reuse through total recycling. In this example, all energy used in the electrochemical process, concentration, acidification, and refining process was ignored, ignoring the generation of value-added by-products at each stage, and the basis for the calculation was based on laboratory test results and Aspen Plus Simulation. Calculated by As a result of the calculation, the existing process was 13.1 MWh / ton FA, and the present example was 11.9 Mwh / ton, and the energy saving effect of about 1.2 MWh / ton (about 10%) was confirmed.

<Comparison of the process conditions of the existing potassium sulfate manufacturing process and the new complex process of the present application>

In order to compare the energy consumption of the existing potassium sulfate manufacturing process and the new complex process of the present application (FIG. 10), the energy consumption of each unit process was estimated to convert the energy saving amount according to the existing potassium sulfate manufacturing process and the development process. In the case of the existing process, the reaction proceeds at a high temperature (Mannheim furnace: 550 ° C.), but in the present embodiment, since the reaction proceeds at room temperature and atmospheric pressure, it was found to be superior to the existing process in terms of economy and stability. In addition, in the present embodiment, formic acid is produced through electrochemical conversion, and formic acid and potassium sulfate are prepared by sulfation of the formate, and formic acid is produced in high purity through evaporation under reduced pressure. Produced and did not cost extra to produce potassium sulfate.

The above description of the present application is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above description, and it should be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present application.

[Description of the code]

100: first reactor

150: first chamber

160: cathode injection line

170: collecting electrode line

200: second chamber

210: anode line injection line

220: anode line collection line

250: thickener injection line

300: thickener

310: first potassium sulfate collection line

320: second reactor injection line

350: second reactor

400: third chamber

410 sulfuric acid injection line

420: separator injection line

450: separator

460: second potassium sulfate collection line

470: formic acid collection line

Claims (14)

1. A first reactor for preparing formate by electrochemical reduction of carbon dioxide in an electrolyte solution containing potassium sulfate;

   A concentrator connected to the first reactor and concentrating an electrolyte solution containing the formate and potassium sulfate prepared in the first reactor to a solid containing formate and potassium sulfate;

   A second reactor connected to the concentrator, for adding sulfuric acid to the solid containing formate and potassium sulfate obtained in the concentrator to prepare a solution containing formic acid and potassium sulfate solids; And

   A separator connected to the second reactor and separating the solution containing the formic acid and the potassium sulfate solid prepared in the second reactor into a formic acid-containing solution and potassium sulfate solid, respectively

   Comprising a device for a complex process of carbon dioxide reduction and formic acid and potassium sulfate production.
2. The method of claim 1,

   Wherein the purity of each of the formic acid and the potassium sulfate is at least 85% high purity, a combined process for producing carbon dioxide reduction and formic acid and potassium sulfate.
3. The method of claim 1,

   The concentration of the formate is at least 5%, the composite process apparatus of carbon dioxide reduction and formic acid and potassium sulfate production.
4. The method of claim 1,

   The first reactor is an electrochemical reduction reactor of carbon dioxide including an electrolyte solution containing a potassium sulfate solution, an anode portion and a cathode portion,

   Supplying carbon dioxide to the cathode, continuously supplying a metal hydroxide to the anode, and applying a voltage or current to the cathode and the anode to reduce the carbon dioxide to continuously obtain formate Become,

   Combined process equipment for carbon dioxide reduction and formic acid and potassium sulfate production.
5. The method of claim 4, wherein

   Wherein the metal hydroxide comprises a hydroxide selected from the group consisting of KOH, NaOH, LiOH, and combinations thereof, the apparatus for a complex process of carbon dioxide reduction and formic acid and potassium sulfate production.
6. The method of claim 4, wherein

   The cathode portion comprises an amalgam electrode comprising a mixture, a composite, or an alloy including Hg and a metal selected from the group consisting of Ag, In, Sn, Pb, Cu, and combinations thereof formed on the surface of the base electrode. Comprising, the apparatus for a composite process of carbon dioxide reduction and formic acid and potassium sulfate production.
7. The method of claim 6,

   Wherein the substrate electrode comprises a porous substrate, plate-like substrate, rod-shaped substrate, or foam (foam) substrate, the apparatus for a composite process of carbon dioxide reduction and formic acid and potassium sulfate production.
8. Formate is obtained by electrochemical reduction of carbon dioxide in an electrolyte solution containing potassium sulfate in a first reactor,

   An electrolytic solution containing the formate and potassium sulfate obtained from the first reactor is transferred to a concentrator and concentrated to a solid containing formate and potassium sulfate,

   Transferring the solid containing formate and potassium sulfate obtained in the concentrator into a second reactor to add sulfuric acid to obtain a solution comprising formic acid and potassium sulfate solids, and

   Separating the solution comprising the formic acid and potassium sulfate solids obtained in the second reactor into a separator and separating the formic acid-containing solution and the potassium sulfate solid, respectively.

   Comprising a composite process of carbon dioxide reduction and formic acid and potassium sulfate production.
9. The method of claim 8,

   Wherein the purity of each of the formic acid and the potassium sulfate is independently of each other high purity of 85% or more, the combined process of carbon dioxide reduction and formic acid and potassium sulfate production.
10. The method of claim 8,

    The concentration of the formate is 5% or more, a complex process of carbon dioxide reduction and formic acid and potassium sulfate production.
11. The method of claim 8,

    The first reactor is an electrochemical reduction reactor of carbon dioxide including an electrolyte solution containing a potassium sulfate solution, an anode portion and a cathode portion,

    Supplying carbon dioxide to the cathode, continuously supplying a metal hydroxide to the anode, and applying a voltage or current to the cathode and the anode to reduce the carbon dioxide to continuously obtain formate Become,

    Combined process of carbon dioxide reduction and formic acid and potassium sulfate production.
12. The method of claim 11,

    Wherein the metal hydroxide comprises a hydroxide selected from the group consisting of KOH, NaOH, LiOH, and combinations thereof, a composite process of carbon dioxide reduction and formic acid and potassium sulfate production.
13. The method of claim 11,

    The cathode portion comprises an amalgam electrode comprising a mixture, a composite, or an alloy including Hg and a metal selected from the group consisting of Ag, In, Sn, Pb, Cu, and combinations thereof formed on the surface of the base electrode. That is, a composite process of carbon dioxide reduction and formic acid and potassium sulfate production.
14. The method of claim 13,

    Wherein the base electrode comprises a porous substrate, plate-like substrate, rod-shaped substrate, or foam (foam) substrate, carbon dioxide reduction and formic acid and potassium sulfate composite process.

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