JP7638933B2 - Electrolyzer - Google Patents

Description

The present invention relates to an electrolytic cell, and more specifically, but not limited to, an electrolytic cell that can be suitably used to produce an aqueous solution of quaternary ammonium hydroxide using an aqueous solution of a quaternary ammonium salt as a raw material.

The following Patent Documents 1 to 4 disclose a method for producing a quaternary ammonium hydroxide aqueous solution using a quaternary ammonium salt aqueous solution as a raw material. To carry out such a production method, an electrolytic cell is used that includes a cathode frame, a cathode plate fixed to the inner surface of the cathode frame, an anode frame, and an anode plate fixed to the inner surface of the anode frame. At least one cation exchange membrane is disposed between the cathode plate and the anode plate, a cathode chamber is defined between the cathode frame and the cation exchange membrane, and an anode chamber is defined between the anode frame and the cation exchange membrane. A cathode side fluid supply passage for supplying a cathode side fluid to the cathode chamber, a cathode side fluid discharge passage for discharging the cathode side fluid from the cathode chamber, an anode side fluid supply passage for supplying an anode side fluid to the anode chamber, and an anode side fluid discharge passage for discharging the anode side fluid from the anode chamber are disposed. More specifically, the cathode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings spaced apart in the width direction and a plurality of lower flow paths extending from a plurality of lower openings spaced apart in the width direction, one of the upper flow paths and the lower flow paths configuring the cathode side fluid discharge path and the other of the upper flow paths and the lower flow paths configuring the cathode side fluid supply path. Similarly, the anode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings spaced apart in the width direction and a plurality of lower flow paths extending from a plurality of lower openings spaced apart in the width direction, one of the upper flow paths and the lower flow paths configuring the anode side fluid discharge path and the other of the upper flow paths and the lower flow paths configuring the anode side fluid supply path. A cathode side fluid, i.e., a quaternary ammonium hydroxide aqueous solution, is circulated through the cathode side fluid supply channel, the cathode chamber, and the cathode side fluid discharge channel, and an anode side fluid, i.e., a quaternary ammonium salt aqueous solution, is circulated through the anode side fluid supply channel, the anode chamber, and the anode side fluid discharge channel.

JP 62-142792 Publication Special Publication No. 8-16274 Special Publication No. 8-19539 JP 2009-13477 A

Thus, in the electrolytic cell as described above, the effective flow path cross-sectional area of the cathode side fluid supply path and the effective flow path cross-sectional area of the cathode side fluid discharge path are set to be substantially the same, and the effective flow path cross-sectional area of the anode side fluid supply path and the effective flow path cross-sectional area of the anode side fluid discharge path are set to be substantially the same. In particular, in an electrolytic cell having the configuration proposed by the present inventors in Japanese Patent Application No. 2022-33651 (i.e., an electrolytic cell having an upper end portion of a cathode plate formed with at least one upper through-opening that matches with the upper opening of a cathode frame, a lower end portion of a cathode plate formed with at least one lower through-opening that matches with the lower opening of the cathode frame, an upper end portion of an anode plate formed with at least one upper through-opening that matches with the upper opening of the anode frame, and a lower end portion of an anode plate formed with at least one lower through-opening that matches with the lower opening of the anode frame, and the upper and lower through-openings formed in the cathode plate and the upper and lower through-openings formed in the anode plate define the effective flow path cross-sectional area of the fluid flow path), the effective flow path area is set to a minimum necessary to achieve maximum electric field efficiency. However, as a result of extensive research and experimentation into the operation of the electrolytic cell, the inventors have recognized that gas is generated in the cathode chamber and anode chamber due to electrolysis, and that in addition to the cathode side fluid and anode side fluid, the generated gas also flows in the cathode side fluid discharge channel and anode side fluid discharge channel, resulting in an increased flow rate in the cathode side fluid discharge channel and anode side fluid discharge channel compared to the cathode side fluid supply channel and anode side fluid supply channel, generating back pressure, which in turn increases the electrolysis voltage and tends to hinder stable operation of the electrolytic cell.

The present invention was made in consideration of the above facts, and its main technical objective is to provide a new and improved electrolytic cell that avoids an increase in electrolysis voltage and ensures stable operation of the electrolytic cell.

In light of the above facts recognized by the inventors, the inventors have found that the above main technical object can be achieved by making the effective flow path cross-sectional area CD of the cathode side fluid discharge channel larger than the effective flow path cross-sectional area CS of the cathode side fluid supply channel, and by making the effective flow path cross-sectional area AD of the anode side fluid discharge channel larger than the effective flow path cross-sectional area AS of the anode side fluid supply channel.

That is, according to the present invention, an electrolytic cell that achieves the above-mentioned main technical object is
an anode frame having an anode plate fixed to its inner surface; an ion exchange membrane disposed between the cathode frame and the anode frame; a cathode side fluid supply passage for supplying a cathode side fluid to a cathode chamber defined between the cathode frame and the ion exchange membrane; a cathode side fluid discharge passage for discharging the cathode side fluid from the cathode chamber; an anode side fluid supply passage for supplying an anode side fluid to an anode chamber defined between the anode frame and the ion exchange membrane; and an anode side fluid discharge passage for discharging the anode side fluid from the anode chamber,
an effective flow path cross-sectional area CD of the cathode side fluid discharge path is larger than an effective flow path cross-sectional area CS of the cathode side fluid supply path, and an effective flow path cross-sectional area AD of the anode side fluid discharge path is larger than an effective flow path cross-sectional area AS of the anode side fluid supply path;
An electrolytic cell is provided.

The effective flow path cross-sectional area CD is 1.1 to 3.0 times the effective flow path cross-sectional area CS (CD = 1.1 to 3.0CS), and the effective flow path cross-sectional area AD is 1.1 to 3.0 times the effective flow path cross-sectional area AS (AD = 1.1 to 3.0AS). In particular, it is preferable that the effective flow path cross-sectional area CD is 1.5 to 2.5 times the effective flow path cross-sectional area CS (CD = 1.5 to 2.5CS), and the effective flow path cross-sectional area AD is 1.5 to 2.5 times the effective flow path cross-sectional area AS (AD = 1.5 to 2.5AS).

In a preferred embodiment,
the cathode frame is provided with at least one upper flow passage extending from an upper opening located at an upper end of the inner surface and at least one lower flow passage extending from a lower opening located at a lower end of the inner surface;
the anode frame is provided with at least one upper flow passage extending from an upper opening located at an upper end of the inner surface and at least one lower flow passage extending from a lower opening located at a lower end of the inner surface;
the cathode plate extends continuously from above the upper opening of the cathode frame to below the lower opening of the cathode frame,
At least one upper through-opening is formed in an upper end of the cathode plate, the upper through-opening being aligned with the upper opening of the cathode frame, and at least one lower through-opening is formed in a lower end of the cathode plate, the lower through-opening being aligned with the lower opening of the cathode frame;
the anode plate extends continuously from above the upper opening of the anode frame to below the lower opening of the anode frame,
At least one upper through-opening is formed in an upper end of the anode plate, the upper through-opening being aligned with the upper opening of the anode frame, and at least one lower through-opening is formed in a lower end of the anode plate, the lower through-opening being aligned with the lower opening of the anode frame;
the upper through-opening of the cathode plate and the upper flow path of the cathode frame constitute one of the cathode side fluid discharge path and the cathode side fluid supply path, and the lower through-opening of the cathode plate and the lower flow path of the cathode frame constitute the other of the cathode side fluid discharge path and the cathode side fluid supply path,
The upper through opening of the anode plate and the upper flow path of the anode frame constitute one of the anode side fluid discharge path and the anode side fluid supply path, and the lower through opening of the anode plate and the lower flow path of the anode frame constitute the other of the anode side fluid discharge path and the anode side fluid supply path.

Preferably, the cathode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings arranged at an upper end of the inner surface at intervals in the width direction, and a plurality of lower flow paths extending from a plurality of lower openings arranged at a lower end of the inner surface at intervals in the width direction,
the anode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings arranged at an upper end of the inner surface at intervals in the width direction, and a plurality of lower flow paths extending from a plurality of lower openings arranged at a lower end of the inner surface at intervals in the width direction,
a plurality of upper through-openings are formed at an upper end of the cathode plate, each of which is aligned with one of the plurality of upper openings of the cathode frame; and a plurality of lower through-openings are formed at a lower end of the cathode plate, each of which is aligned with one of the plurality of lower openings of the cathode frame;
a plurality of upper through-openings are formed at an upper end of the anode plate, each of which is aligned with one of the plurality of upper openings of the anode frame; and a plurality of lower through-openings are formed at a lower end of the anode plate, each of which is aligned with one of the plurality of lower openings of the anode frame;
the number of the upper through openings of the cathode plate and the upper flow paths of the cathode frame or the lower through openings of the cathode plate and the lower flow paths of the cathode frame constituting the cathode side fluid discharge path is greater than the number of the lower through openings of the cathode plate and the lower flow paths of the cathode frame or the upper through openings of the cathode plate and the upper flow paths of the cathode frame constituting the cathode side fluid supply path,
The number of the upper through openings of the anode plate and the upper flow paths of the anode frame, or the lower through openings of the anode plate and the lower flow paths of the anode frame, which constitute the anode side fluid discharge path, is greater than the number of the lower through openings of the anode plate and the lower flow paths of the anode frame, or the upper through openings of the anode plate and the upper flow paths of the anode frame, which constitute the anode side fluid supply path.

Advantageously, the upper and lower openings of the cathode frame and the upper and lower openings of the cathode plate have a circular cross-sectional shape, and the upper and lower openings of the anode frame and the upper and lower openings of the anode plate have a circular cross-sectional shape. The cathode plate and the anode plate are preferably constructed from rectangular plates.

In a preferred embodiment of the present invention, at least one cation exchange membrane is disposed between the cathode plate and the anode plate in the electrolytic cell as described above, and an aqueous solution of quaternary ammonium hydroxide is produced using an aqueous solution of a quaternary ammonium salt as a raw material using such an electrolytic cell.

In the electrolytic cell of the present invention, the effective flow path cross-sectional area CD of the cathode side fluid discharge channel is larger than the effective flow path cross-sectional area CS of the cathode side fluid supply channel, and the effective flow path cross-sectional area AD of the anode side fluid discharge channel is larger than the effective flow path cross-sectional area AS of the anode side fluid supply channel. Therefore, as will be clearly understood from the examples described later, an increase in electrolysis voltage is avoided and stable operation of the electrolytic cell is ensured.

1 is a simplified cross-sectional view of a preferred embodiment of an electrolytic cell constructed in accordance with the present invention; 2 is a simplified cross-sectional view taken along line II-II in FIG. 1, showing a cathode frame and a cathode plate in the electrolytic cell shown in FIG. 1; 2 is a partially enlarged cross-sectional view showing an upper opening of a cathode frame, an upper through opening formed in a cathode plate, and an upper communication opening formed in a gasket in the electrolytic cell shown in FIG. 1 . 3 is a simplified cross-sectional view similar to that of FIG. 2, showing a cathode frame and a cathode plate in a modified electrolytic cell constructed in accordance with the present invention; FIG.

The present invention will now be described in further detail with reference to the accompanying drawings, which show a preferred embodiment of an electrolytic cell constructed in accordance with the present invention.

1 and 2, the illustrated electrolytic cell constructed according to the present invention includes a hollow rectangular parallelepiped housing 2 constituted by a cathode frame 4 (FIG. 1), an anode frame 6 (FIG. 1), a cathode side upper wall member 8, an anode side upper wall member 10, a cathode side lower wall member 12, an anode side lower wall member 14, a cathode side front wall member 16 (FIG. 2), an anode side front wall member (not shown), a cathode side rear wall member 18 (FIG. 2), and an anode side rear wall member (not shown). The cathode frame 4, the anode frame 6, the cathode side front wall member 16, the anode side front wall member, the cathode side rear wall member 18, and the anode side rear wall member extend substantially vertically, and the cathode side upper wall member 8, the anode side upper wall member 10, the cathode side lower wall member 12, and the anode side lower wall member 14 extend substantially horizontally. The base end surface (the right end surface in Fig. 1 ) of the cathode side upper wall member 8 is connected to the inner upper edge portion of the cathode frame 4 by an appropriate connecting means such as a fastening screw or an adhesive, and the base end surface (the right end surface in Fig. 1 ) of the cathode side lower wall member 12 is connected to the inner lower edge portion of the cathode frame 4 by an appropriate connecting means. Similarly, the base end surface (the left end surface in Fig. 1 ) of the anode side upper wall member 10 is connected to the inner upper edge portion of the anode frame 6 by an appropriate connecting means, and the base end surface (the left end surface in Fig. 1 ) of the anode side lower wall member 14 is connected to the inner lower edge portion of the anode frame 6 by an appropriate connecting means. The cathode side front wall member 16 is connected to the front surface of the cathode frame 4, and the anode side front wall member is connected to the front surface of the anode frame 6 by an appropriate connecting means, while the cathode side rear wall member 18 is connected to the rear surface of the cathode frame 4, and the anode side rear wall member is connected to the rear surface of the anode frame 6 by an appropriate connecting means. Instead of connecting the cathode side and anode side upper wall members 8 and 10, the lower wall members 12 and 14, and the front wall member 16 and the rear wall member 18 to the cathode frame 4 or the anode frame 6 as described above, these wall members can be formed integrally in advance and connected to the cathode frame 4 or the anode frame 6. Furthermore, the wall portions can be formed integrally with the cathode frame 4 or the anode frame 6. Furthermore, when the upper wall members 8 and 10, the lower wall members 12 and 14, and the front wall member 16 and the rear wall member 18 are integrally formed, they can also be fixed to the cathode frame 4 or the anode frame 6 via a sealing member interposed therebetween. As the sealing member, an extension portion of a gasket 38 described later can be used by extending the gasket 38 from a size corresponding to the cathode plate 32 or the anode plate 56 to a size corresponding to the cathode frame 4 or the anode frame 6. The cathode frame 4, the anode frame 6, the cathode side upper wall member 8, the anode side upper wall member 10, the cathode side lower wall member 12, the anode side lower wall member 14, the cathode side front wall member 16, the anode side front wall member, the cathode side rear wall member 18 and the anode side rear wall member may be in the form of a solid block or plate except for the openings and flow paths described later, and can be formed from an appropriate synthetic resin such as an olefin-based resin such as polypropylene and polyethylene, a vinyl chloride-based resin, and a fluorine-based resin. An appropriate sealing member (not shown) such as a gasket can be interposed between the interconnected portions of the cathode frame 4, the anode frame 6, the cathode side upper wall member 8, the anode side upper wall member 10, the cathode side lower wall member 12, the anode side lower wall member 14, the cathode side front wall member 16, the anode side front wall member, the cathode side rear wall member 18, and the anode side rear wall member .

Continuing the explanation with reference to Figure 3 along with Figures 1 and 2, a plurality of (six in the illustrated case) upper openings 20 (one of which is shown by a dashed line and one of which is shown by a solid line in Figures 1 and 3, respectively) are formed at equal intervals in the width direction (the direction perpendicular to the paper surface in Figure 1, and the left-right direction in Figure 2) at the upper end of the inner surface (the left side surface in Figure 1) of the cathode frame 4, and a plurality of (six in the illustrated case) upper flow paths 22 (one of which is shown by a dashed line and one of which is shown by a solid line in Figures 1 and 3, respectively) are formed in the cathode frame 4, extending substantially horizontally from each of the upper openings 20 and penetrating the cathode frame 4. Similarly, a plurality of (three in the illustrated case) lower openings 24 (one of which is shown by a broken line in FIG. 1 ) are formed at equal intervals in the width direction (the direction perpendicular to the paper surface in FIG. 1 , the left-right direction in FIG. 2 ) at the lower end of the inner surface (the left side surface in FIG. 1 ), and a plurality of (three in the illustrated case) lower flow paths 26 (one of which is shown by a broken line in FIG. 1 ) are formed in the cathode frame 4, extending substantially horizontally from each of the lower openings 24 through the cathode frame 4. The upper opening 20 and the lower opening 24 may be circular, and the cross-sectional shape of the upper flow path 22 and the cross-sectional shape of the lower flow path 26 may be circular matching the circular shapes of the upper opening 20 and the lower opening 24. The upstream flow path 22 and the downstream flow path 26 are connected by an outer flow path (not shown) arranged on the outside of the housing 2, and the outer flow path 31 (part of which is shown in FIG. 2) is also provided with a circulation pump, a product storage tank, and multiple valve members for flow control (the outer flow path and the components arranged therein as described above are well known to those skilled in the art, so a detailed description of these will be omitted in this specification).

A cathode plate 32 is fixed to the inner surface of the cathode frame 4. In the illustrated embodiment, the cathode plate 32 extends continuously from above the upper opening 20 formed in the cathode frame 4 to below the lower opening 24 formed in the cathode frame 4. The cathode plate 32 is a rectangular plate made of a suitable conductive metal such as nickel, and its upper end surface abuts or is close to the inner surface (i.e., the lower surface) of the cathode side upper wall member 8, its lower end surface abuts or is close to the inner surface (i.e., the upper surface) of the cathode side lower wall member 12, its front side surface abuts or is close to the inner surface (i.e., the rear surface) of the front wall member 16, and its rear side surface abuts or is close to the inner surface (i.e., the front surface) of the rear wall member 18. The cathode plate 32 can be conveniently fixed to the cathode frame 4 by, for example, screwing fastening screws (not shown) through the cathode plate 32 into the cathode frame 4 at the four corners of the cathode plate 32. A plurality of (six in the illustrated example) upper through-openings 34 are formed at the upper end of the cathode plate 32 at equal intervals in the width direction (direction perpendicular to the paper surface in FIG. 1, left-right direction in FIG. 2), and a plurality of (three in the illustrated example) lower through-openings 36 are formed at the lower end of the cathode plate 32 at equal intervals in the width direction (direction perpendicular to the paper surface in FIG. 1, left-right direction in FIG. 2) (the upper through-openings 34 and the lower through-openings 36 will be further mentioned later). Each of the upper through-openings 34 formed in the cathode plate 32 is positioned so as to be aligned with each of the upper openings 20 formed in the upper end of the cathode frame 4. In the illustrated embodiment, each of the upper through-openings 34 has the same shape (hence circular) and dimensions as each of the upper openings 20. Similarly, it is important that each of the lower through-openings 36 formed in the cathode plate 32 is positioned so as to be aligned with each of the lower openings 24 formed in the lower end of the cathode frame 4. In the illustrated embodiment, each of the lower through openings 36 is of the same shape (hence circular) and size as each of the lower openings 24. Preferably, the upper through openings 34 (and upper openings 20) are located proximate the upper ends of the cathode plates 32, and the lower through openings 36 (and lower openings 24) are located proximate the lower ends of the cathode plates 32.

Continuing the explanation with reference to FIG. 1 and FIG. 3, it is preferable that a gasket 38 is interposed between the cathode frame 4 and the cathode plate 32. The gasket 38 can stably fix the cathode plate 32 to the cathode frame 4, and can also prevent corrosion due to the penetration of liquid into the interface between the cathode frame 4 and the cathode plate 32. This gasket 38 may be a rectangular plate having substantially the same dimensions as the cathode plate 32 (as described above, the gasket 38 can also be made to a size corresponding to the cathode frame 4), and can be made of a suitable elastomer, for example, silicone rubber, ethylene propylene rubber, chloroprene rubber, soft polyvinyl chloride, butyl rubber, butadiene rubber, or fluororubber. When the gasket 38 is interposed between the cathode frame 4 and the cathode plate 32, fastening screws (not shown) can be screwed into the cathode frame 4 at the four corners of the cathode plate 32 through the gasket 38 together with the cathode plate 32. At the upper end of the gasket 38, a plurality of (six in the illustrated example) upper communication openings 40 are formed which communicate with each of the upper through openings 34 formed in the cathode plate 32 and each of the upper openings 20 formed in the cathode frame 4, and at the lower end of the gasket 38, a plurality of (three in the illustrated example) lower communication openings 42 are formed which communicate with each of the lower through openings 36 formed in the cathode plate 32 and each of the lower openings 24 formed in the cathode frame 4. As can be clearly understood by referring to FIG. 3, the upper communication openings 40 and the lower communication openings 42 formed in the gasket 38 are formed in a plurality of (three in the illustrated example) lower communication openings 42 which communicate with each of the lower through openings 36 formed in the cathode plate 32 and each of the lower openings 24 formed in the cathode frame 4. It is desirable that the upper and lower communication openings 40 and 42 formed in the gasket 38 are larger than the upper and upper openings 34 and 20 and the lower and lower openings 36 and 24. If the upper and lower communication openings 40 and 42 formed in the gasket 38 are substantially the same size as the upper and upper openings 34 and 20 and the lower and lower openings 36 and 24, the gasket 38 will expand somewhat during continuous operation of the electrolytic cell, causing the upper and lower communication openings 40 and 42 to shrink and be displaced, which will tend to cause the communication between the upper and upper openings 34 and 20 and the communication between the lower and lower openings 36 and 24 to become insufficient or to be damaged. The opening 42 may be circular and have a diameter greater by a predetermined length than the diameters of the upper through opening 34 and the upper opening 20 and the lower through opening 36 and the lower opening 24. The upper communication opening 40 and the lower communication opening 42 do not necessarily have to be concentric with the upper through opening 34 and the upper opening 20 and the lower through opening 36 and the lower opening 24, but may be eccentric. The diameters of the upper communication opening 40 and the lower communication opening 42 and the degree of eccentricity with respect to the upper through opening 34 and the upper opening 20 and the lower through opening 36 and the lower opening 24 are experimentally set based on the expansion and displacement of the gasket 38 due to the continuous operation of the electrolytic cell. The larger the upper communication opening 40 and the lower communication opening 42 formed in the gasket 38 are, the less likely the communication will be insufficient or damaged. However, as described below, the area of the back surface of the cathode plate 32 that comes into contact with the liquid increases, which causes electrolytic corrosion and corrosion, and increases the amount of electrode metal mixed into the liquid. For this reason, the preferred sizes of the upper communication opening 40 and the lower communication opening 42 formed in the gasket 38 are +30 mm or less, preferably +20 mm or less, and more preferably +10 mm or less, of the upper through opening 34 and the upper opening 20, and the lower through opening 36 and the lower opening 24. Furthermore, if a material that does not easily expand is used for the gasket 38, the possibility of the communication being insufficient or damaged is reduced even if the size of the upper communication opening 40 and the lower communication opening 42 is close to the size of the upper through opening 34 and the upper opening 20, and the lower through opening 36 and the lower opening 24. Therefore, the material used for the gasket 38 preferably has a linear expansion coefficient of 3×10 ⁻⁴ (1/° C.) or less, more preferably 1.5×10 ⁻⁴ (1/° C.) or less, and most preferably 1×10 ⁻⁴ (1/° C.) or less.

In the illustrated embodiment, the anode frame 6 is substantially the same as the cathode frame 4 described above. More specifically, the cathode frame 4 and the anode frame 6 are symmetrical with respect to a virtual plane extending perpendicular to the paper surface in FIG. 1. Therefore, the anode frame 6 is provided with an upper opening 44, an upper flow passage 46, a lower opening 48, and a lower flow passage 50. To avoid duplication, detailed descriptions of the upper opening 44, the upper flow passage 46, the lower opening 48, and the lower flow passage 50 are omitted. The upper flow passage 46 and the lower flow passage 50 are connected by an outer flow passage (not shown) disposed outside the housing 2, and the outer flow passage is also provided with a circulation pump, a raw material storage tank, and a plurality of valve members for flow control (the outer flow passage and the above-mentioned components disposed therein are well known to those skilled in the art, and detailed descriptions thereof are omitted in this specification).

An anode plate 56 is fixed to the inner surface of the anode frame 6. In the illustrated embodiment, the anode plate 56 is substantially the same as the cathode plate 32, except that it is made of a suitable conductive metal suitable for an anode, for example titanium plated with indium oxide. More specifically, the cathode plate 32 and the anode plate 56 are symmetrical with respect to a virtual plane extending perpendicular to the paper surface in FIG. 1. Therefore, the anode plate 56 has a rectangular shape that extends continuously from above the upper opening 44 formed in the anode frame 6 to below the lower opening 48 formed in the anode frame 6. The anode plate 56 is formed with an upper through opening 58 and a lower through opening 60 that are aligned with the upper opening 44 and the lower opening 48 formed in the anode frame 6, respectively. To avoid duplication, a detailed description of the anode plate 56 is omitted.

In the illustrated embodiment, a gasket 62 is also interposed between the anode frame 6 and the anode plate 56. This gasket 62 is also substantially the same as the gasket 38 interposed between the cathode frame 4 and the cathode plate 32. More specifically, the gasket 38 and the gasket 62 are symmetrical with respect to a virtual plane extending perpendicular to the paper surface in FIG. 1. Therefore, the gasket 62 is formed with an upper communication opening 64 that communicates the upper opening 44 formed in the anode frame 6 with the upper through-opening 58 formed in the anode plate 56, as well as a lower communication opening 66 that communicates the lower opening 48 formed in the anode frame 6 with the lower through-opening 60 formed in the anode plate 56. To avoid duplication of explanation, detailed explanation of the gasket 62 and the upper communication opening 64 and the lower communication opening 66 will be omitted.

1, in the illustrated embodiment, a cation exchange membrane 68 is disposed between the cathode plate 32 and the anode plate 56. The cation exchange membrane 68, which may be of a known form, has a rectangular plate shape, with its upper edge held between the cathode side upper wall member 8 and the anode side upper wall member 10, its lower edge held between the cathode side lower wall member 12 and the anode side lower wall member 14, the front side edges of the cathode frame 4 and the anode frame 6 held between the cathode side front wall member 16 and the anode side front wall member, and the rear side edges of the cathode frame 4 and the anode frame 6 held between the cathode side rear wall member 18 and the anode side rear wall member. Appropriate seal members (not shown) can be interposed between the cation exchange membrane 68 and each of the cathode side upper wall member 8 and the anode side upper wall member 10, the cathode side lower wall member 12 and the anode side lower wall member 14, the cathode side front wall member 16 and the anode side front wall member, and the cathode side rear wall member 18 and the anode side rear wall member .

In the electrolytic cell as described above, a cathode chamber or product chamber 70 is defined between the cathode plate 32 and the cation exchange membrane 68, and an anode chamber, i.e., a raw material chamber 72, is defined between the anode plate 56 and the cation exchange membrane 68. Initially, a diluted aqueous solution of quaternary ammonium hydroxide (or pure water) is circulated through the product chamber 70, more specifically, through one of the lower flow path 26 and the upper flow path 22 formed in the cathode frame 4, and flows out of the product chamber 70 through the other. At the same time, an aqueous solution of quaternary ammonium salt is circulated through the raw material chamber 72, more specifically, through one of the lower flow path 50 and the upper flow path 46 formed in the anode frame 6, and flows out through the other. An electrolytic voltage is applied between the cathode plate 32 and the anode plate 56. Thus, the concentration of the aqueous solution of quaternary ammonium hydroxide circulating through the product chamber 70 is gradually increased. Such electrolytic action is well known to those skilled in the art, so a detailed description thereof is omitted in this specification. In the illustrated embodiment of the electrolytic cell constructed according to the present invention, the cathode plate 32 and the anode plate 56 each extend continuously from above the upper openings 20 and 44 formed in the cathode frame 4 and the anode frame 6 to below the lower openings 24 and 48. The cathode plate 32 and the anode plate 56 each have upper through openings 34 and 58 and lower through openings 36 and 60 that match the upper openings 20 and 44 and the lower openings 24 and 48. Therefore, the cathode plate 32 and the anode plate 56 extend over almost the entire inner surface of the cathode frame 4 and the anode frame 6, respectively. Therefore, the relative current-carrying area of the cathode plate 32 and the anode plate 56 with respect to the size of the electrolytic cell is large, and thus electrolysis is performed with improved electrolysis efficiency.

In an electrolytic cell constructed according to the present invention, it is important that the effective flow cross-sectional area CD of the cathode-side fluid discharge channel is larger than the effective flow cross-sectional area CS of the cathode-side fluid supply channel, and similarly, the effective flow cross-sectional area AD of the anode-side fluid discharge channel is larger than the effective flow cross-sectional area AS of the anode-side fluid supply channel. The term "effective flow cross-sectional area" means the minimum cross-sectional area in the channel. In the illustrated embodiment, the effective flow cross-sectional area CD of the cathode-side fluid discharge channel is determined by the six upper through-openings 34 formed in the cathode plate 32, as well as the upper communication opening 40 continuing to the upper through-openings 34, the upper opening 20, the upper flow channel 22, and a part of the outer flow channel 31, and the cross-sectional areas of the upper communication openings 34, the upper opening 20, the upper flow channel 22, and a part of the outer flow channel 31 are equal to or larger than the cross-sectional area of the upper through-opening 34, and therefore the effective flow cross-sectional area CD of the cathode-side fluid discharge channel is determined by the total cross-sectional area of the six upper through-openings 34. Further, the effective flow path cross-sectional area CS of the cathode side fluid supply path is determined by the three lower through-openings 36 formed in the cathode plate 32 as well as the lower communication opening 42, the lower opening 24, the lower flow path 26, and a part of the outer flow path 31 continuing to the lower through-openings 36, and the cross-sectional areas of the lower communication opening 42, the lower opening 24, the lower flow path 26, and the part of the outer flow path 31 are equal to or larger than the cross-sectional area of the lower through-opening 36, and therefore the effective flow path cross-sectional area CS of the cathode side fluid supply path is determined by the total cross-sectional area of the three lower through-openings 36. In particular, from the viewpoint of suppressing an increase in back pressure due to the discharged fluid, it is preferable that the cross-sectional area of the part of the outer flow path 31 is larger than the cross-sectional areas of the upper through-opening 34 to the lower through-opening 36. Specifically, the cross-sectional area of the part of the outer flow path 31 is preferably 1.0 times or more, more preferably 1.5 times or more, of the cross-sectional areas of the upper through-opening 34 to the lower through-opening 36. The cross-sectional area of a portion of the outer flow passage 31 relative to the upper through opening 34 to the lower through opening 36 is appropriately determined taking into consideration the effective flow passage cross-sectional area and the supply amount of fluid.

In the illustrated embodiment, as described above, six upper through-openings 34 are formed at equal intervals in the width direction (direction perpendicular to the paper surface in FIG. 1, left-right direction in FIG. 2), whereas three lower through-openings 36 are formed at equal intervals in the width direction (direction perpendicular to the paper surface in FIG. 1, left-right direction in FIG. 2), and the cross-sectional areas of the six upper through-openings 34 and the three lower through- openings 36 are all the same. Therefore, the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is twice the effective flow path cross-sectional area CS of the cathode-side fluid supply path. As will be understood from the examples described later, the effective flow path cross-sectional area CD of the cathode-side fluid discharge path is preferably 1.1 to 3.0 times (CD = 1.1 to 3.0CS), particularly 1.5 to 2.5 times (CD = 1.5 to 2.5CS), the effective flow path cross-sectional area CS of the cathode-side fluid supply path.

The cross-sectional areas of the upper through-opening 34 and the lower through-opening 36 formed in the cathode plate 32 are desirably set to the minimum necessary to achieve maximum electric field efficiency. However, as a result of extensive research and repeated experiments by the inventors of the present invention on the operation of the electrolytic cell, gas is generated in the cathode chamber or product chamber 70 due to electrolysis, and the generated gas flows in the cathode-side fluid discharge channel in addition to the cathode-side fluid. Therefore, if the effective flow path cross-sectional area CD of the cathode-side fluid discharge channel is set to be the same as the effective flow path cross-sectional area CS of the cathode-side fluid supply channel, the flow rate in the cathode-side fluid discharge channel is increased compared to the cathode-side fluid supply channel, generating back pressure, which tends to increase the electrolysis voltage and hinder stable operation of the electrolytic cell. However, in the electrolytic cell constructed according to the present invention, the effective flow path cross-sectional area CD of the cathode-side fluid discharge channel is set to be larger than the effective flow path cross-sectional area CS of the cathode-side fluid supply channel, so that an increase in the electrolysis voltage is avoided and stable operation of the electrolytic cell is ensured, as will be clearly understood from the examples described below.

In the embodiment illustrated in FIGS. 1 to 3 as described above, the number of the upper through openings 34 (six) is made greater than the number of the lower through openings 36 (three) to make the effective flow path cross-sectional area CD of the cathode-side fluid discharge channel greater than the effective flow path cross-sectional area CS of the cathode-side fluid supply channel; however, if desired, the numbers of the upper through openings 34 and the lower through openings 36 may be made the same and the cross-sectional area of each of the upper through openings 34 may be set greater than the cross-sectional area of each of the lower through openings 36 to make the effective flow path cross-sectional area CD of the cathode-side fluid discharge channel greater than the effective flow path cross-sectional area CS of the cathode-side fluid supply channel. In the modification shown in Fig. 4, three upper through openings 34 are formed at the upper end of the cathode plate 32 at equal intervals in the width direction (left-right direction in Fig. 4) (thus, three upper communication openings 40, three upper openings 20, and three upper flow passages 22 are also formed), and three lower through openings 36 are formed at the lower end of the cathode plate 32 at equal intervals in the width direction (left-right direction in Fig. 4), and the cross-sectional area of each of the upper through openings 34 is set to be twice that of each of the lower through openings 36. However, according to the experience of the present inventors, the discharge flow tends to be smoother when the number of the upper through openings 34 is greater than the number of the lower through openings 36, rather than when the cross-sectional area of each of the upper through openings 34 is set to be larger than the cross-sectional area of each of the lower through openings 36.

In the above-described embodiment and modified example, a plurality of upper through openings 34 and lower through openings 36 are formed at equal intervals in the width direction in the cathode plate 32, but if desired, a single upper through opening and a single lower through opening that extend elongatedly in the width direction in the cathode plate 32 can be formed, and the cross-sectional area of the upper through opening 34 can be made larger than the cross-sectional area of the lower through opening 36.

Furthermore, in the above-described embodiment and modified example, the cathode plate 32 extends continuously from above the upper opening 20 formed in the cathode frame 4 to below the lower opening 24 formed in the cathode frame 4. A plurality of upper through-openings 34 are formed at the upper end of the cathode plate 32 at equal intervals in the width direction (the direction perpendicular to the paper surface in FIG. 1, the left-right direction in FIGS. 2 and 4). A plurality of upper through-openings 34 are formed at the lower end of the cathode plate 32 at equal intervals in the width direction (the direction perpendicular to the paper surface in FIG. 1, the left-right direction in FIGS. 2 and 4). Although several lower through-openings 36 are formed, if desired, for example, the cathode plate 32 may be configured to extend from below the upper opening 20 formed in the cathode frame 4 to above the lower opening 24 formed in the cathode frame 4, and the upstream end of the cathode side fluid discharge path may be defined by the upper opening 20 formed in the cathode frame 4 and the downstream side of the cathode side fluid supply path may be defined by the lower opening 24 formed in the cathode frame 4 without forming the upper through-openings 34 and the lower through-openings 36 in the cathode plate 32. In such a case, the effective flow path cross-sectional area of the cathode side fluid discharge path is defined by the total cross-sectional area of the upper openings 20, and the effective flow path cross- sectional area of the cathode side fluid supply path is defined by the total cross-sectional area of the lower openings 24.

The relationship between the effective flow cross-sectional area CD of the cathode side fluid discharge path and the effective flow cross-sectional area CS of the cathode side fluid supply path has been specifically explained, but the relationship between the effective flow cross-sectional area AD of the anode side fluid discharge path and the effective flow cross-sectional area AS of the anode side fluid supply path is exactly the same, and in order to avoid duplication of explanation, a specific explanation of the relationship between the effective flow cross-sectional area AD of the anode side fluid discharge path and the effective flow cross-sectional area AS of the anode side fluid supply path will be omitted.

Examples 1 to 3 and Comparative Example 1
An electrolytic cell having the configuration shown in Figures 1 to 3 or 4 was prepared and operated in a constant current control mode, and the average value of the cell voltage (the voltage between the anode plate and the cathode plate) during operation was detected. In Examples 1 to 3, the effective flow cross-sectional area CD of the cathode side fluid discharge channel was larger than the effective flow cross-sectional area CS of the cathode side fluid supply channel, and similarly, the effective flow cross-sectional area AD of the anode side fluid discharge channel was larger than the effective flow cross-sectional area AS of the anode side fluid supply channel. On the other hand, in Comparative Example 1, the effective flow cross-sectional area CD of the cathode side fluid discharge channel and the effective flow cross-sectional area CS of the cathode side fluid supply channel were the same, and similarly, the effective flow cross-sectional area AD of the anode side fluid discharge channel and the effective flow cross-sectional area AS of the anode side fluid supply channel were the same. The average value of the cell voltage was as shown in Table 1.

The details of the components of the electrolytic cell and their operating conditions are as follows:
Operating time: 30 days
Cathode: Nickel plate (thickness 2 mm, surface dimensions 1 m x 1 m)
Anode: Titanium plate with indium oxide plating on the surface (thickness 2 mm,
Surface dimensions: 1m x 1m)
Cation exchange membrane: product name from Chemours Company
Replacement membrane (1mm thick) sold as "N324"
Gasket: EPDM (The diameter of the upper and lower communication openings is the corresponding upper
2 mm larger than the diameter of the side through-hole and the lower through-hole, respectively)
Raw material (anode side fluid): Methylammonium chloride aqueous solution Product (cathode side fluid): Methylammonium hydroxide aqueous solution
Current: 1000A (10A/dm ² )
Operating temperature: 70°C
Electrolytic cell assembly temperature: 20°C
Raw material (anode side fluid) flow rate: 20L/min
Product (cathode side fluid) flow rate: 20L/min

Although the present invention has been described in detail with reference to the attached drawings illustrating preferred embodiments thereof, it goes without saying that the present invention is not limited to such embodiments, and various modifications and alterations are possible without departing from the technical scope of the present invention. For example, in the illustrated embodiment, one cation exchange membrane 68 is disposed between the cathode plate 32 and the anode plate 56, but the present invention can also be applied to an electrolytic cell in which multiple exchange membranes (cation exchange membranes and anion exchange membranes) are disposed between the cathode plate 32 and the anode plate 56.

Description of the embodiment 2: Housing of electrolytic cell 4: Cathode frame 6: Anode frame 8: Cathode side upper wall member 10: Anode side upper wall member 12: Cathode side lower wall member 14: Anode side lower wall member 16: Cathode side front wall member 18: Cathode side rear wall member 20: Upper opening 22: Upper flow path 24: Lower opening 26: Lower flow path 31: Outer flow path 32: Cathode plate 34: Upper through opening 36: Lower through opening 38: Gasket 40: Upper communication opening 42: Lower communication opening 44: Upper opening 46: Upper flow path 48: Lower opening 50: Lower flow path 56: Anode plate 58: Upper through opening 60: Lower through opening 62: Gasket 64: Upper communication opening 66: Lower communication opening 68: Cation exchange membrane 70: Product room (cathode room)
72: Raw material room (anode room)

Claims (7)

An electrolytic cell for producing an aqueous solution of quaternary ammonium hydroxide from an aqueous solution of a quaternary ammonium salt, comprising:
the cathode frame having a cathode plate fixed to its inner surface, an anode frame having an anode plate fixed to its inner surface, an ion exchange membrane disposed between the cathode frame and the anode frame, a cathode side fluid supply channel for supplying a cathode side fluid to a cathode chamber defined between the cathode frame and the ion exchange membrane, a cathode side fluid discharge channel for discharging the cathode side fluid from the cathode chamber, an anode side fluid supply channel for supplying an anode side fluid to an anode chamber defined between the anode frame and the ion exchange membrane, and an anode side fluid discharge channel for discharging the anode side fluid from the anode chamber,
an effective flow path cross-sectional area CD of the cathode side fluid discharge path is larger than an effective flow path cross-sectional area CS of the cathode side fluid supply path, and an effective flow path cross-sectional area AD of the anode side fluid discharge path is larger than an effective flow path cross-sectional area AS of the anode side fluid supply path,
the cathode frame is provided with at least one upper flow passage extending from an upper opening located at an upper end of the inner surface and at least one lower flow passage extending from a lower opening located at a lower end of the inner surface;
the anode frame is provided with at least one upper flow passage extending from an upper opening located at an upper end of the inner surface and at least one lower flow passage extending from a lower opening located at a lower end of the inner surface;
the cathode plate extends continuously within the cathode chamber from above the upper opening of the cathode frame to below the lower opening of the cathode frame,
At least one upper through-opening is formed in an upper end of the cathode plate, the upper through-opening being aligned with the upper opening of the cathode frame, and at least one lower through-opening is formed in a lower end of the cathode plate, the lower through-opening being aligned with the lower opening of the cathode frame;
the anode plate extends continuously within the anode chamber from above the upper opening of the anode frame to below the lower opening of the anode frame,
At least one upper through-opening is formed in an upper end of the anode plate, the upper through-opening being aligned with the upper opening of the anode frame, and at least one lower through-opening is formed in a lower end of the anode plate, the lower through-opening being aligned with the lower opening of the anode frame;
the upper through-opening of the cathode plate and the upper flow path of the cathode frame constitute one of the cathode side fluid discharge path and the cathode side fluid supply path, and the lower through-opening of the cathode plate and the lower flow path of the cathode frame constitute the other of the cathode side fluid discharge path and the cathode side fluid supply path,
the upper through-opening of the anode plate and the upper flow path of the anode frame constitute one of the anode-side fluid discharge path and the anode-side fluid supply path, and the lower through-opening of the anode plate and the lower flow path of the anode frame constitute the other of the anode-side fluid discharge path and the anode-side fluid supply path.
Electrolytic cell characterized by: The electrolytic cell according to claim 1, wherein the effective flow cross-sectional area CD is 1.1 to 3.0 times the effective flow cross-sectional area CS (CD = 1.1 to 3.0CS), and the effective flow cross-sectional area AD is 1.1 to 3.0 times the effective flow cross-sectional area AS (AD = 1.1 to 3.0AS). The electrolytic cell according to claim 2, wherein the effective flow cross-sectional area CD is 1.5 to 2.5 times the effective flow cross-sectional area CS (CD = 1.5 to 2.5CS), and the effective flow cross-sectional area AD is 1.5 to 2.5 times the effective flow cross-sectional area AS (AD = 1.5 to 2.5AS). the cathode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings arranged at an upper end of the inner surface at intervals in the width direction, and a plurality of lower flow paths extending from a plurality of lower openings arranged at a lower end of the inner surface at intervals in the width direction,
the anode frame is provided with a plurality of upper flow paths extending from a plurality of upper openings arranged at an upper end of the inner surface at intervals in the width direction, and a plurality of lower flow paths extending from a plurality of lower openings arranged at a lower end of the inner surface at intervals in the width direction,
a plurality of upper through-openings are formed at an upper end of the cathode plate, each of which is aligned with one of the plurality of upper openings of the cathode frame; and a plurality of lower through-openings are formed at a lower end of the cathode plate, each of which is aligned with one of the plurality of lower openings of the cathode frame;
a plurality of upper through-openings are formed at an upper end of the anode plate, each of which is aligned with one of the plurality of upper openings of the anode frame; and a plurality of lower through-openings are formed at a lower end of the anode plate, each of which is aligned with one of the plurality of lower openings of the anode frame;
the number of the upper through openings of the cathode plate and the upper flow paths of the cathode frame or the lower through openings of the cathode plate and the lower flow paths of the cathode frame constituting the cathode side fluid discharge path is greater than the number of the lower through openings of the cathode plate and the lower flow paths of the cathode frame or the upper through openings of the cathode plate and the upper flow paths of the cathode frame constituting the cathode side fluid supply path,
the number of the upper through openings of the anode plate and the upper flow paths of the anode frame or the lower through openings of the anode plate and the lower flow paths of the anode frame constituting the anode-side fluid discharge path is greater than the number of the lower through openings of the anode plate and the lower flow paths of the anode frame or the upper through openings of the anode plate and the upper flow paths of the anode frame constituting the anode-side fluid supply path.
2. The electrolytic cell of claim 1 . the upper opening and the lower opening of the cathode frame and the upper through-opening and the lower through-opening of the cathode plate have a circular cross-sectional shape,
the upper opening and the lower opening of the anode frame and the upper through opening and the lower through opening of the anode plate have a circular cross-sectional shape;
5. The electrolytic cell of claim 4 . 2. The electrolytic cell of claim 1 , wherein said cathode plate and said anode plate comprise rectangular plates. A method for producing an aqueous solution of quaternary ammonium hydroxide from an aqueous solution of a quaternary ammonium salt as a raw material, using the electrolytic cell according to any one of claims 1 to 3, in which at least one cation exchange membrane is disposed between the cathode plate and the anode plate.

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