CN117813419A

CN117813419A - Rupture-resistant partition wall for electrolytic cells comprising solid electrolyte ceramics

Info

Publication number: CN117813419A
Application number: CN202280052861.7A
Authority: CN
Inventors: P·H·赖因斯贝格; M·霍恩
Original assignee: Evonik Operations GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2021-07-29
Filing date: 2022-07-19
Publication date: 2024-04-02
Also published as: WO2023006493A1; EP4124677A1; KR20240034777A; JP2024527769A; US20240344219A1; EP4377498A1

Abstract

In a first aspect, the invention relates to an electrolytic cell (E) comprising a cell (E) suitable for use in an electrolytic cellA partition wall (W). The partition wall (W) comprises at least two alkali metal cation conductive solid electrolyte ceramic pieces (F _A ) And (F) _B ) They are separated from each other by at least one separating element (T). This arrangement is more flexible and the individual ceramics have more degrees of freedom to react to temperature fluctuations, for example by shrinking or expanding, than if the separating wall (W) according to the prior art comprises a one-piece solid electrolyte. This therefore increases the stability of the ceramic to mechanical stresses. The electrolytic cell (E) comprises a cathode chamber (K _K ) The cathode chamber is separated from an adjacent chamber by a partition wall (W), the adjacent chamber being an intermediate chamber (K) of the electrolytic cell (E) _M ). In a second aspect, the invention relates to a method for producing an alkali metal alkoxide solution in an electrolytic cell (E) according to the first aspect of the invention.

Description

Rupture-resistant partition wall for electrolytic cells comprising solid electrolyte ceramics

In a first aspect, the invention relates to an electrolytic cell E comprising a dividing wall W suitable for use in the electrolytic cell E. The partition wall W comprises at least two alkali metal cation conducting solid ceramic pieces F separated from each other by at least one partition element T _A And F _B . This arrangement is more flexible and the individual ceramic pieces have a higher degree of freedom available to react to temperature fluctuations (e.g. by shrinking or expanding) than if the partition wall W according to the prior art comprises a one-piece solid electrolyte. This increases the stability to mechanical stresses in the ceramic.

The electrolytic cell E comprises a cathode chamber K separated from the adjacent chamber by a partition wall W _K The adjacent chamber is the middle chamber K of the electrolytic cell E _M 。

In a second aspect, the invention relates to a method for producing an alkali metal alkoxide solution in an electrolytic cell E according to the first aspect of the invention.

Background

Electrochemical production of alkali metal alkoxide solutions is an important industrial process, which is described, for example, in DE 103 60 7588 A1, US2006/0226022 A1 and WO 2005/059205 A1. The principle of these methods is reflected in the electrolytic cell, wherein an alkali metal salt, such as sodium chloride or NaOH solution, is present in the anode compartment and the alcohol in question or an alcohol solution with a low concentration of alkali metal alkoxide, such as sodium methoxide or sodium ethoxide, is present in the cathode compartment. The cathodic compartment and anodic compartment are separated by a ceramic such as NaSICON or potassium or lithium analogues that conduct the alkali metal ions used. When an alkali chloride salt is used, chlorine gas is formed at the anode and hydrogen gas and alkoxide ions are formed at the cathode when an electric current is applied. Since alkali metal ions migrate from the intermediate chamber into the cathode chamber via the ceramic selective thereto, the charge is balanced. The charge balance between the intermediate and anode compartments results from the migration of cations when using a cation exchange membrane or from the migration of anions when using an anion exchange membrane, or from the migration of both types of ions when using a non-specific diffusion barrier. This increases the concentration of alkali metal alkoxides in the cathode chamber and decreases the concentration of sodium ions in the anolyte.

NaSICON solid state electrolytes are also used in the electrochemical production of other compounds:

WO 2014/008410 A1 describes an electrolytic process for producing titanium or rare earth elements. The method is based on TiO ₂ And the corresponding acid to form titanium chloride, which is then reacted with sodium alkoxide to form titanium alkoxide and NaCl, which is finally electrolytically converted to elemental titanium and sodium alkoxide.

WO 2007/082092 A2 and WO 2009/059315 A1 describe processes for producing biodiesel, in which triglycerides are first converted into the corresponding alkali metal triglycerides by means of alkoxides produced by NaSICON electrolysis and reacted in a second step with electrolytically generated protons to give glycerol and the corresponding alkali metal hydroxides.

However, these solid electrolyte ceramics generally have some drawbacks. During operation of the electrolytic cell, fluctuations in the temperature within the cell inevitably occur, which lead to expansion or contraction of the solid electrolyte ceramic. As these ceramics are brittle, this can lead to cracking of the ceramic.

This problem occurs in particular during the repeated starting and stopping processes which are unavoidable in electrolytic operations. During heating and cooling there are expansion and contraction phases, which cause the ceramic to move back and forth in the cell. These movements can lead to ceramic cracking due to uncontrolled distribution of forces in the ceramic.

This can result in a loss of integrity, which can lead to leakage of brine into the alcohol, or leakage of alcohol into the brine. As a result, the electrolytic product, i.e., the alkoxide solution, is diluted. In addition, the cell itself may lose integrity and leak.

It is therefore an object of the present invention to provide an electrolytic cell which does not have these disadvantages.

Another disadvantage of conventional electrolytic cells in this technical field stems from the fact that solid electrolytes do not have long-term stability against aqueous acids. This is problematic because during electrolysis in the anode chamber the pH drops due to the oxidation process (for example in the case of halogen production by disproportionation or by oxygen formation). The attack of NaSICON solid state electrolytes by these acidic conditions is to such an extent that the process cannot be used on an industrial scale. To solve this problem, various methods have been described in the prior art.

For example, three-compartment cells have been proposed in the prior art. These three-compartment cells are known in the field of electrodialysis, for example US 6,221,225 B1.

For example WO 2012/048032 A2 and US2010/0044242A1 describe electrochemical methods for producing sodium hypochlorite and similar chlorine-containing compounds in such a three-compartment cell. The cathode and intermediate chambers of the cell are separated here by a cation permeable solid electrolyte such as NaSICON. In order to protect it from the acidic anolyte, for example, the intermediate chamber is supplied with solution from the cathode chamber. US2010/0044242A1 also describes in fig. 6 the possibility of mixing the solution from the intermediate chamber with the solution from the anode chamber outside the chamber to obtain sodium hypochlorite.

Such tanks for producing or purifying alkali metal alkoxides have also been proposed in the prior art.

For example, US 5,389,211 describes a process for purifying alkoxide solutions, wherein a three-compartment cell is used, wherein the compartments are delimited from one another by a cation-selective solid electrolyte or a nonionic partition wall. The intermediate chamber serves as a buffer chamber to prevent the purified alkoxide or hydroxide solution from the cathode chamber from mixing with the contaminated solution from the anode chamber.

DE 42 33 191 A1 describes the electrolytic recovery of alkoxides from salts and alkoxides in multi-chamber cells and in multiple cell stacks.

WO 2008/076327A1 describes a process for producing alkali metal alkoxides. The process uses a three-compartment cell in which the intermediate compartment has been filled with an alkali metal alkoxide (see for example paragraphs [0008] and [0067] of WO 2008/076327 A1). This protects the solid electrolyte separating the intermediate chamber from the cathode chamber from the solution present in the anode chamber, which becomes more acidic during electrolysis. WO 2009/073062A1 describes a similar arrangement. However, a disadvantage of this arrangement is that alkali metal alkoxide solution is the desired product as buffer solution by consumption and continued through contamination. Another disadvantage of the method described in WO 2008/076327A1 is that the formation of alkoxides in the cathode chamber depends on the diffusion rate of alkali metal ions through two membranes or solid electrolytes. This in turn results in a slow down of alkoxide formation.

Another problem is caused by the geometry of the three-chamber cell. In such chambers the intermediate chamber is separated from the anode chamber by a diffusion barrier and from the cathode chamber by an ion conducting ceramic. During electrolysis, this inevitably creates a pH gradient and dead volume. This can damage the ion conducting ceramic member, thereby increasing the voltage requirements of the electrolysis and/or causing ceramic cracking.

Although this effect occurs throughout the electrolytic cell, the drop in pH is particularly critical in the intermediate cell, as the intermediate cell is defined by the ion conducting ceramic member. The gases are typically formed at the anode and cathode such that there is at least some degree of mixing in these chambers. In contrast, this mixing does not occur in the intermediate chamber, thereby accumulating a pH gradient therein. This undesirable effect is enhanced because brine is typically pumped relatively slowly through the electrolytic cell.

It is therefore a further object of the present invention to provide an improved process for the electrolytic production of alkali metal alkoxides and an electrolytic cell which is particularly suitable for such a process. These cells do not have the above-mentioned drawbacks and in particular to ensure improved protection of the solid electrolyte before the pH gradient is established and to use the reactants more economically than in the prior art.

Disclosure of Invention

The problem addressed by the present invention is solved by an electrolytic cell E according to the first aspect of the invention<1>To be solved, which comprises a partition wall W. Partition wall W<16>Comprising a surface O _KK <163>Side S of (2) _KK <161>And side S _KK <161>Opposite has a surface O _A/MK <164>Side S of (2) _A/MK <162>. The partition wall further comprises a partition wall formed by at least one partition element T<17>At least two alkali metal cation-conducting solid electrolyte ceramic pieces F separated from each other _A <18>And F _B <19>. Partition wall W<16>Comprising an alkali metal cation-conducting solid electrolyte ceramic part and in particular also a separator element T<17>Where it is possible to pass through the surface O _KK <163>And via surface O _A/MK <164>Direct contact.

Thus, in a first aspect, the invention relates to an electrolytic cell E <1>, comprising

At least one anode chamber K _A <11>Having at least one inlet Z _KA <110>At least one outlet A _KA <111>Comprising an anode E _A <113>Internal I of (2) _KA <112>，

At least one cathodic compartment K _K <12>Having at least one inlet Z _KK <120>At least one outlet A _KK <121>Comprising a cathode E _K <123>Internal I of (2) _KK <122>A kind of electronic device

At least one intermediate chamber K arranged therebetween _M <13>Having at least one inlet Z _KM <130>At least one outlet A _KM <131>And internal I _KM <132>，

Wherein I is _KA <112>And I _KM <132>Then pass through diffusion barrier layer D<14>Separated from each other, and A _KM <131>Via the connecting piece V _AM <15>Is connected to inlet Z _KA <110>So that liquid can pass through the connecting piece V _AM <15>From I _KM <132>Delivery to I _KA <112>，

Wherein the method comprises the steps of

-I _KK <122>And I _KM <132>Through the partition wall W<16>Apart from each other,

it is characterized in that

Partition wall W<16>Comprising an alkali metal cation-conducting solid ceramic part, in particular also a separating element T<17>Via surface O _KK <163>On the side S _KK <161>Upper direct contact internal I _KK <122>，

And is also provided with

Partition wall W<16>Comprising an alkali metal cation-conducting solid ceramic part, in particular also a separating element T<17>Via surface O _A/MK <164>On the side S _A/MK <162>Upper direct contact internal I _KM <132>。

In a second aspect, the invention relates to a process for producing a solution L of an alkali metal alkoxide XOR in an alcohol ROH ₁ Wherein X is an alkali metal cation and R is an alkyl group having 1 to 4 carbon atoms,

wherein the following steps (β1), (β2), (β3) which are carried out simultaneously are carried out in the electrolytic cell E according to the first aspect of the invention:

(beta 1) solution L comprising alcohol ROH ₂ Transport through K _K ，

(beta 2) an aqueous solution L of a neutral or basic salt S containing X as cation ₃ Transport through K _M Then via V _AM Then pass through K _A ，

(beta 3) at E _A And E is _K A voltage is applied between the two electrodes,

this is at outlet A _KK Where the solution L is provided ₁ Wherein L is ₁ The XOR concentration in (a) is higher than L ₂ The concentration of the XOR in (a),

and this is at outlet a _KA Aqueous solution L where S is provided ₄ Wherein L is ₄ In S concentration lower than L ₃ S concentration in (b).

Drawings

3.1 FIGS. 1A and 1B

Fig. 1A (= "fig. 1A") shows an electrolytic cell E not according to the invention. It comprises a cathode chamber K _K <12>And anode chamber K _A <11>。

Cathode chamber K _K <12>Including internal I _KK <122>Cathode E in (a) _K <123>Inlet Z _KK <120>And outlet A _KK <121>。

Anode chamber K _A <11>Including internal I _KA <112>Anode E of (B) _A <113>Inlet Z _KA <110>And outlet A _KA <111>。

The two chambers are arranged on the outer wall of the two-chamber pool E<80>Is a boundary. Internal I _KK <122>Also by NaSICON solid electrolyte F selectively permeable to sodium ions _A <18>Partition wall and inner part I composed of sheets _KA <112>And (5) separating. NaSICON solid electrolyte F _A <18>Extending over the entire depth and height of the two-compartment cell E. The partition wall has two sides S _KK <161>And S is _A/MK <162>Its surface O _KK <163>And O _A/MK <164>Contact with corresponding internal I _KK <122>Or I _KA <112>。

Aqueous sodium chloride solution L having a pH of 10.5 ₃ <23>Via inlet Z _KA <110>Is introduced into the interior I against the direction of gravity _KA <112>Is a kind of medium.

Methanolic solution L of sodium methoxide ₂ <22>Via inlet Z _KK <120>Introduction into interior I _KK <122>Is a kind of medium.

At the same time at cathode E _K <123>And anode E _A <113>Between which a voltage is applied. This results in electrolyte L ₂ <22>Reduction of methanol in (C) to internal I _KK <122>To obtain methoxide and H ₂ (CH ₃ OH+e ^- →CH ₃ O ^- +1/2H ₂ ). At the same time, sodium ions from the interior I _KA <112>By NaSICON solid electrolyte F _K <18>Diffusion into interior I _KK <122>Is a kind of medium. Overall, this increases the internal I _KK <122>The concentration of sodium methoxide in the water provides a sodium methoxide concentration ratio L ₂ <22>Sodium methoxide methanol solution L with high sodium methoxide concentration ₁ <21>。

Internal I _KA <112>In which the chloride ions oxidize to produce molecular chlorine (Cl) ^- →1/2Cl ₂ +e ^- ). At outlet A _KA <111>In the water solution L is obtained ₄ <24>Wherein is with L ₃ <23>In contrast, the content of NaCl was reduced. Chlorine (Cl) in water ₂ ) According to reaction Cl ₂ +H ₂ O.fwdarw.HOCl+HCl forms hypochlorous acid and hydrochloric acid, which further reacts with water molecules in an acidic manner. This acidity compromises NaSICON solid electrolyte F _A <18>。

Fig. 1B (= "fig. 1B") shows another electrolytic cell E not according to the invention. The three-chamber cell E comprises a cathode chamber K _K <12>Anode chamber K _A <11>And an intermediate chamber K arranged therebetween _M <13>。

Intermediate chamber K _M <13>Including internal I _KM <132>Inlet Z _KM <130>And outlet A _KM <131>。

Internal I _KA <112>Via the connecting piece V _AM <15>Connected to the interior I _KM <132>。

The three chambers are arranged on the outer wall of the three-chamber pool E<80>Is a boundary. Intermediate chamber K _M <13>Internal I of (2) _KM <132>Also by a NaSICON solid electrolyte F which is selectively permeable to sodium ions _A <18>Partition wall composed of sheetsAnd cathode chamber K _K <12>Internal I of (2) _KA <122>And (5) separating. NaSICON solid electrolyte F _A <18>Extending over the entire depth and height of the three-compartment cell E. The partition wall has two sides S _KK <161>And S is _A/MK <162>Its surface O _KK <163>And O _A/MK <164>Contact with corresponding internal I _KK <122>Or I _KM <132>。

Intermediate chamber K _M <13>Internal I of (2) _KM <132>And further additionally pass through diffusion barrier layer D<14>And anode chamber K _A <11>Internal I of (2) _KA <112>And (5) separating. NaSICON solid electrolyte F _A <18>And a diffusion barrier layer D<14>Extending over the entire depth and height of the three-compartment cell E. Diffusion barrier layer D<14>Is a cation exchange membrane (sulfonated PTFE).

In the embodiment according to fig. 1B, the connection piece V _AM <15>Formed outside the electrolytic cell E, in particular by a tube or hose, the material of which may be selected from rubber, metal and plastic. Connecting piece V _AM <15>From the intermediate chamber K _M <13>Internal I of (2) _KM <132>Partition wall W leading to three-chamber cell E _A <80>Outer anode chamber K _A <11>Internal I of (2) _KA <112>Is a kind of medium. Connecting piece V _AM <15>Outlet A _KM <131>Is connected to inlet Z _KA <110>Outlet A _KM <131>In the intermediate chamber K _M <13>Penetrating the outer wall W of the electrolytic cell E at the bottom _A <80>Inlet Z _KA <110>In the anode chamber K _A <11>Penetrating the outer wall W of the electrolytic cell E at the bottom _A <80>。

Aqueous sodium chloride solution L having a pH of 10.5 ₃ <23>Via inlet Z _KM <130>Introduced into the intermediate chamber K in the direction of gravity _M Internal I of (2) _KM <132>Is a kind of medium. In from intermediate chamber K _M <13>Outlet A of (2) _KM <131>And to anode chamber K _A <11>Inlet Z of (2) _KA <110>The connecting piece V formed between _AM <15>Intermediate chamber K _M <13>Internal I of (2) _KM <132>Is connected to anode chamber K _A <11>Internal I of (2) _KA <112>. Through the connecting piece V _AM <15>Sodium chloride solution L ₃ <23>From inside I _KM <132>Delivery to interior I _KA <112>. Methanol solution L of sodium methoxide ₂ <22>Via inlet Z _KK <120>Delivery to interior I _KK <122>。

At the same time at cathode E _K <123>And anode E _A <113>Between which a voltage is applied. This results in electrolyte L ₂ <22>Reduction of methanol in (C) to give internal I _KK <122>To obtain methoxide and H ₂ (CH ₃ OH+e ^- →CH ₃ O ^- +1/2H ₂ ). At the same time, sodium ions flow from the intermediate chamber K _M <103>Internal I of (2) _KM <132>By NaSICON solid electrolyte F _A <18>Diffusion into interior I _KK <122>Is a kind of medium. Overall, this increases the internal I _KK <122>The concentration of sodium methoxide in the water, which provides a sodium methoxide concentration ratio L ₂ <22>Sodium methoxide methanol solution L with high sodium methoxide concentration ₁ <21>。

Internal I _KA <112>In which the chloride ions are oxidized to give molecular chlorine (Cl) ^- →1/2Cl ₂ +e ^- ). At outlet A _KA <111>Where an aqueous solution L is obtained ₄ <24>Wherein is with L ₃ <23>In contrast, the content of NaCl was reduced. Chlorine (Cl) in water ₂ ) According to reaction Cl ₂ +H ₂ O.fwdarw.HOCl+HCl forms hypochlorous acid and hydrochloric acid, which further reacts with water molecules in an acidic manner. This acidity compromises NaSICON solid electrolyte F _A <18>But is limited to the anode chamber K by its arrangement in a three-chamber cell _A <11>Thus far from the NaSICON solid electrolyte F in the electrolytic cell E _K <18>. This significantly increases its lifetime.

3.2 FIGS. 2A and 2B

Fig. 2A (= "fig. 2)A ") shows a partition wall W<16>Is an embodiment of the present invention. Partition wall W<16>Comprising passing through a dividing element T <17>Are separated from each other and are each fixed to the separation element T without a gap<17>Two NaSICON solid electrolyte ceramic pieces F _A <18>And F _B <19>And (3) upper part. Separation element T<17>Having a rectangular parallelepiped geometry, wherein F _A <18>And F _B <19>Fixed to the separating element T without play<17>On opposite sides (e.g., by adhesive). With surface O _KK <163>Side S of (2) _KK <161>Lying in the plane of the drawing and not visible in fig. 2A having a surface O _A/MK <164>Side S of (2) _A/MK <162>Located behind the plane of the drawing.

Fig. 2B (= "fig. 2B") shows the partition wall W<16>Is an embodiment of the present invention. This includes four NaSICON solid electrolyte ceramic pieces F _A <18>、F _B <19>、F _C <28>、F _D <29>They pass through the dividing element T<17>Are separated from each other and are each fixed to the separation element T without a gap<17>And (3) upper part. Separation element T<17>Has a cross shape, wherein F _A <18>、F _B <19>、F _C <28>And F _D <29>Is adhesively connected to the separating element T<17>On opposite sides. With surface O _KK <163>Side S of (2) _KK <161>Lying in the plane of the drawing and not visible in fig. 2B, has a surface O _A/MK <164>Side S of (2) _A/MK <162>Located behind the plane of the drawing.

3.3 FIGS. 3A-3C

Fig. 3A (= "fig. 3A") shows a detailed view highlighted with a dashed circle in fig. 2A and 2B. As described, the corresponding solid electrolyte ceramic member F _A <18>And F _B <19>For example by means of an adhesive to the separating element T <17>And (3) upper part.

Fig. 3B (= "fig. 3B") shows another embodiment of the present invention of the partition wall W. Here, the separationElement T<17>Having two recesses (grooves) in which the two solid electrolyte ceramic pieces F _A <18>And F _B <19>Fitting in these two pockets (grooves). For this purpose, the solid electrolyte ceramic part F can be mechanically adjusted accordingly _A <18>And F _B <19>Is a shape of an edge of the substrate. Furthermore, a seal Di is used<40>Seal Di<40>For example with adhesive, to the separating element T<17>And a corresponding solid electrolyte ceramic member F _A <18>Or F _B <19>And (3) upper part. Here the separating element T<17>May be formed of two or more parts<171>And<172>the components may be fixed to each other as shown by the dashed lines in fig. 3B. Solid electrolyte ceramic part F given proper geometry _A <18>And F _B <19>And the edge shape thereof can match the solid electrolyte ceramic piece F _A <18>And F _B <19>Clamped between the two parts<171>And<172>between which this further increases the separating element T<17>With ceramic part F _A <18>Or F _B <19>Is to be used in the connection of the partition wall W<16>Is described herein).

Fig. 3C (= "fig. 3C") shows another embodiment of the present invention of the partition wall W. This corresponds to that described in FIG. 3B, except that the two solid electrolyte ceramic pieces F _A <18>And F _B <19>Assembled separating element T <17>The pits (grooves) in (a) are not concave but are one point.

3.4 FIGS. 4A-4D

Fig. 4A (= "fig. 4A") to 4D show another embodiment of the present invention of the partition wall W <16 >.

Partition wall W shown in FIG. 4<16>Corresponds to the partition wall W shown in FIG. 2A<16>Except that it also comprises a frame element R<20>. Frame element R<20>Completely cover and remove O _KK <163>And O _A/MK <164>Outside partition wall W<16>Is a surface of the substrate. Frame element R<20>Not associated with separating element T<17>Together in a one-piece form.

Fig. 4B (= "fig. 4B") shows another embodiment of the present invention of the partition wall W <16 >. This corresponds to the embodiment shown in FIG. 4A, except that it includes two frame elements R <20> defining the upper and lower surfaces of the dividing wall W <16 >.

Fig. 4C (= "fig. 4C") shows the partition wall W<16>Is an embodiment of the present invention. Partition wall W shown in FIG. 4C<16>Corresponds to the partition wall W shown in FIG. 2B<16>Except that it also comprises a frame element R<20>. Frame element R<20>Completely cover and remove O _KK <163>And O _A/MK <164>Outside partition wall W<16>Is a surface of the substrate. Frame element R<20>Not associated with separating element T<17>Together in a one-piece form.

Fig. 4D (= "fig. 4D") shows another embodiment of the present invention of the partition wall W <16 >. This corresponds to the embodiment shown in FIG. 4C, except that it includes two frame elements R <20> defining the upper and lower surfaces of the dividing wall W <16 >.

3.5 FIGS. 5A and 5B

Fig. 5A (= "fig. 5A") shows an electrolytic cell E not according to the invention. This corresponds to the electrolytic cell shown in FIG. 1A, except for the partition wall W<16>Cathode chamber K _K <12>Internal I of (2) _KK <122>And anode chamber K _A <11>Internal I of (2) _KA <112>And (5) separating. The partition wall is shown in fig. 2A and 2B.

Fig. 5B (= "fig. 5B") shows an electrolytic cell E not according to the invention. This corresponds to the electrolytic cell shown in FIG. 1A, except for the partition wall W<16>Cathode chamber K _K <12>Internal I of (2) _KK <122>And anode chamber K _A <11>Internal I of (2) _KA <112>And (5) separating. Partition wall W<16>As shown in fig. 4A to 4D. Frame element R<20>Forming an outer wall W _A <80>Such that if the solid electrolyte ceramic member is a partition wall W<16>A part of (a) is divided into a partition wall W<16>Included solid electrolyte ceramicsThe porcelain being protected from passing through the dividing wall W<16>Pressure acting thereon. In addition, the solid electrolyte ceramic member is fully inserted into the electrolytic cell to insert the internal I _KK <122>And internal I _KA <112>Separated in that they are not partially hidden by the outer wall.

3.6 FIGS. 6A and 6B

Fig. 6A (= "fig. 6A") shows an electrolytic cell E according to the first aspect of the invention<1>. This corresponds to the electrolytic cell shown in FIG. 1B, except for the partition wall W<16>Cathode chamber K _K <12>Internal I of (2) _KK <122>And intermediate chamber K _M <13>Internal I of (2) _KM <132>And (5) separating. Partition wall W<16>As shown in fig. 4A to 4D.

Fig. 6B (= "fig. 6B") shows an electrolytic cell E according to the first aspect of the invention<1>. This corresponds to cell E shown in FIG. 6A<1>The difference is that from the intermediate chamber K _M <13>Internal I of (2) _KM <132>To anode chamber K _A <11>Internal I of (2) _KA <112>Is connected with the connecting piece V of (2) _AM <15>By forming a diffusion barrier layer D<14>The middle through hole is formed. The perforation may be in the diffusion barrier layer D<14>Or may be from the diffusion barrier layer D<14>Is already present therein (for example in the case of woven fabrics such as filter cloths or metal braids).

3.7 FIGS. 7A and 7B

Fig. 7A (= "fig. 7A") shows a partition wall W of the present invention<16>Is described in detail below. It is formed by passing through the dividing element T<17>Four NaSICON solid electrolyte ceramic pieces F separated from each other _A <18>、F _B <19>、F _C <28>And F _D <29>Composition, separation element T<17>Comprising two halves<171>And<172>. Partition wall W<16>Also comprises two halves<201>And<202>assembled frame element R<20>。

The partition wall W <16> is composed of two foldable parts, wherein the half <171> of the partition element T <17> is present in one piece together with the half <201> of the frame element R <20>, and the half <171> of the partition element T <17> is present in one piece together with the half <201> of the frame element R <20 >. The two parts can optionally be connected to each other via a hinge <50> and can be locked in place in the folded state via a lock <60 >.

The four Nasicon solid electrolyte ceramic pieces F _A <18>、F _B <19>、F _C <28>And F _D <29>Sandwiched between these halves, in each case acting as a seal Di<40>A ring for sealing.

The left side of FIG. 7A shows a partition wall W<16>Has a surface O _KK <163>Side S of (2) _KK <161>Is a front view of the same. Serving as a seal Di<40>Is represented by the dashed outline. The right side of the figure shows the partition wall W<16>Is a side view of (c).

Fig. 7B (= "fig. 7B") shows the partition wall W of the present invention<16>Is described in detail below. This corresponds to the embodiment depicted in fig. 7A, except that it includes nine NaSICON solid electrolyte ceramic pieces F _A <18>、F _B <19>、F _C <28>、F _D <29>、F _E <30>、F _F <31>、F _G <32>、F _H <33>、F _I <34>。

Detailed Description

4.1 partition wall W

In a first aspect, the invention relates to an electrolytic cell E comprising a dividing wall W. The dividing wall W is therefore particularly suitable as dividing wall in an electrolytic cell, in particular in an electrolytic cell E.

The partition wall W includes at least two alkali metal cation-conducting solid electrolyte ceramic members ("alkali metal cation-conducting solid electrolyte ceramic members" abbreviated as "ASC" hereinafter) F separated from each other by a partition element T _A And F _B 。

The partition wall W includes two opposite sidesSide S _KK And S is _A/MK This means side S _A/MK And side S _KK Opposite (and vice versa). These two sides S _KK And S is _A/MK In particular comprising planes substantially parallel to each other.

The geometry of the partition wall W is not further limited in other respects and may be adapted in particular to the cross section of the electrolytic cell E in which it is used. For example, the partition wall W may have a rectangular parallelepiped geometry and thus have a rectangular cross section, or a frustoconical or cylindrical geometry and thus have a circular cross section.

Optionally, the partition wall W may also have a cuboid geometry with rounded corners or protrusions (and possibly further holes). The partition wall W has protrusions ("rabbit ears") by which the partition wall W can be fixed to the electrolytic cell or frame portions of the partition wall W can be fixed to each other.

Side S of partition wall W _KK With surface O _KK And side S of partition wall W _A/MK With surface O _A/MK 。

The feature "partition wall" means that the partition wall W is liquid-tight. This means that the ASC and the at least one separating element T abut each other without gaps. Therefore, there is no gap between the partition element T and ASC included in the partition wall W through which the aqueous solution, the alcoholic solution, the alcohol or the water can pass from the side S _KK To the side S _A/MK Or from side S _A/MK To the side S _KK 。

If there are two or more pairs of alkali metal cation conducting solid electrolyte ceramic pieces comprised by the partition wall W and especially also opposite sides of the partition element T, which are directly accessible via their surfaces, they are referred to as S in the context of the present invention _KK And S is _A/MK Preferably the pair of opposite sides of (a) comprises a maximum surface area O _KK And O _A/MK Is the same as that of (1) for each pair. If the corresponding pair of opposing sides include the same surface area, one skilled in the art can select a pair as having a surface O _KK And O _A/MK S of (2) _KK And S is _A/MK 。

In the presence of two or more pairs of partition walls W comprising an alkali metal cation-conducting solid electrolyte ceramic member and in particular also opposite sides of the partition element T, which may be in direct contact with the partition walls W via their surfaces, partition walls W comprising different surface areas of the respective pairs of opposite sides are preferred, in this case referred to as S in the context of the present invention _KK And S is _A/MK Is the pair of opposite sides comprising the maximum surface area O _KK And O _A/MK Is provided.

The partition wall W of the present invention also includes embodiments in which the partition wall W comprises more than two ASCs, for example four or nine or twelve ASCs, wherein at least two ASCs but not all ASCs are separated from each other by a partition element T, wherein the ASCs are not separated from each other by a partition element T directly adjacent to each other. However, this requires a precise fit of the corresponding adjacent ASCs to preclude the formation of a gap therebetween through which liquid or water or alcohol solution can pass from the side S _KK Flow direction side S _A/MK . It is therefore advantageous and preferred that in the partition wall W all ASCs comprised by the partition wall W are separated from each other by at least one partition element T, which means that no ASC directly adjoins another ASC, i.e. no partition element T is interposed between them.

The partition wall W is also characterized in that ASC included in the partition wall W can pass through the surface O _KK And via surface O _A/MK The two are in direct contact.

With respect to the ASCs comprised by the partition wall W, "directly contactable" means some surface O _KK And O _A/MK Formed by the surface of the ASC comprised by the partition wall W, which means that at both surfaces O _KK And O _A/MK The partition walls W comprise ASCs that are directly accessible so that they can be moved between the two surfaces O _KK And O _A/MK Where it is wetted, for example, by an aqueous solution, an alcoholic solution, an alcohol or water.

The arrangement of ASCs in the partition wall W means that for each ASC comprised by the partition wall W there is a lateral side S _KK Surface O on _KK To the side S _A/MK Surface O on _A/MK Which results in a complete passage through the corresponding ASC。

Typically, the at least one separation element T may also be via the surface O _KK And via surface O _A/MK Is in direct contact with at least a portion of both.

With respect to the at least one dividing element T comprised by the dividing wall W, "directly contactable" means a surface O _KK And O _A/MK Is formed by the surfaces of the separating element T, which means that the separating element T is formed on said two surfaces O _KK And O _A/MK Is directly accessible so that the separating element T is accessible at said two surfaces O _KK And O _A/MK Where it is wetted, for example, by an aqueous solution, an alcoholic solution, an alcohol or water.

More specifically, arranging the partition wall T in the partition wall W means that, for the partition element T comprised by the partition wall W, there is a flow from the side S _KK Surface O on _KK To the side S _A/MK Surface O on _A/MK This is led through the separating element T and possibly through the seal Di but not through the ASC.

In a preferred embodiment of the partition wall W according to the invention, the surface O _KK From 50% to 95%, more preferably from 60% to 90%, even more preferably from 70% to 85%, of the ASC comprised by the partition wall W, wherein even more preferably the surface O _KK Is formed by the separating element T and, if appropriate, the frame element R.

In a preferred embodiment of the partition wall W according to the invention, the surface O _A/MK From 50% to 95%, more preferably from 60% to 90%, even more preferably from 70% to 85%, of the surface O is also formed by ASCs comprised by the partition wall W _A/MK Is formed by the separating element T and, if appropriate, the frame element R.

In another preferred embodiment, the partition wall W comprises at least four ASCs- -F _A 、F _B 、F _C And F _D And even more preferably includes exactly four ASCs-F _A 、F _B 、F _C And F _D 。

In another preferred embodiment, the partition wall W includes at leastNine ASCs- -F _A 、F _B 、F _C 、F _D 、F _E 、F _F 、F _G 、F _H And F _I And even more preferably includes exactly nine ASC-F _A 、F _B 、F _C 、F _D 、F _E 、F _F 、F _G 、F _H And F _I 。

In another preferred embodiment, the partition wall W comprises at least twelve ASCs- -F _A 、F _B 、F _C 、F _D 、F _E 、F _F 、F _G 、F _H 、F _I 、F _J 、F _K And F _L And even more preferably includes exactly twelve ASC-F _A 、F _B 、F _C 、F _D 、F _E 、F _F 、F _G 、F _H 、F _I 、F _J 、F _K And F _L 。

In contrast to conventional dividing walls in prior art cells, the inventive arrangement of at least two ASCs alongside one another in the dividing wall W leads to spreading of the ASCs in the other direction in the event of temperature fluctuations occurring in the operation of the cell. In prior art cells, naSICON sheets used as dividing walls are framed by the outer walls of the cell or by solid plastic frames. In this way it is not possible to dissipate the mechanical stresses generated when expanding in NaSICON, which may lead to ceramic cracking.

In contrast, the individual ASCs within the partition wall W of the invention abut the partition element T, which results in two advantageous effects, both of which increase the long-term stability of the ASCs:

each ASC has a further available degree of freedom, i.e. the size it can expand. In addition to expansion in the z-direction (i.e. beyond the thickness of the ceramic plate at right angles to the plane of the partition wall W), expansion in the x-and/or y-direction, i.e. in the horizontal and vertical directions in the plane of the partition wall W, is now also possible. When the ASC (e.g. as a solid sheet) spans the cross section of the cell and abuts the solid wall of the cell, this expansion direction is absent or at least greatly restricted;

The effect of dividing into a plurality of small ASCs is that the absolute value of the stresses generated in the smaller ASCs is also smaller and can be dissipated more quickly than in a partition wall of the same size consisting of only one ASC, so that stresses which lead to ASC cracking do not build up as quickly.

As a result, the cracking tendency of the "finely divided" ASC in the partition wall W is significantly reduced compared to the use of one sheet.

4.1.1 alkali cation conductive solid electrolyte ceramic article "ASC"

The partition wall W includes a useful alkali metal cation conductive solid electrolyte ceramic member F _A 、F _B Etc. are any solid electrolytes by which the cation, especially alkali metal cations, even more preferably sodium cations, can be removed from S _A/MK Side transport to S _KK And (3) sides. Such solid electrolytes are known to the person skilled in the art and are described, for example, in DE 10 2015 013 155 A1; WO 2012/048032 A2, [0035 ]],[0039],[0040]A segment; US 2010/0044242 A1 [0040 ]],[0041]A segment; DE 10360758 A1 [014 ]]To [025 ]]Segments. They are commercially available under the name NaSICON, liSICON, KSICON. Sodium ion conductive solid state electrolytes are preferred, even more preferably having a NaSICON structure. NaSICON structures that can be used in accordance with the present invention are also described, for example, in N.Anantharamulu, K.Koteswara Rao, G.Rambabu, B.Vijaya Kumar, velchuri Radha, M.Vithal, JMater Sci 2011,46,2821-2837.

In a preferred embodiment of the partition wall W, the alkali metal cation conductive solid ceramic member comprised by the partition wall W independently has the formula M ^I _1+2w+x-y+z M ^II _w M ^III _x Zr ^IV _2-w-x-y M ^V _y (SiO ₄ ) _z (PO ₄ ) _3-z NaSICON structure of (c).

Where M is ^I Selected from Na ⁺ 、Li ⁺ Preferably Na ⁺ 。

Where M is ^II Is a divalent metal cation, preferably selected from Mg ²⁺ 、Ca ²⁺ 、Sr ²⁺ 、Ba ²⁺ 、Co ²⁺ 、Ni ²⁺ More preferably from Co ²⁺ 、Ni ²⁺ 。

Where M is ^III Is a trivalent metal cation, preferably selected from Al ₃ ⁺ 、Ga ³⁺ 、Sc ³⁺ 、La ³⁺ 、Y ³⁺ 、Gd ³⁺ 、Sm ³⁺ 、Lu ³⁺ 、Fe ³ ⁺ 、Cr ³⁺ More preferably selected from Sc ³⁺ 、La ³⁺ 、Y ³⁺ 、Gd ³⁺ 、Sm ³⁺ Particularly preferably selected from Sc ³⁺ 、Y ³⁺ 、La ³⁺ 。

Where M is ^V Is a pentavalent metal cation, preferably selected from V ⁵⁺ 、Nb ⁵⁺ 、Ta ⁵⁺ 。

Roman index I, II, III, IV, V indicates how oxidized the corresponding metal cation is present.

w, x, y, z is a real number, where 0.ltoreq.x <2, 0.ltoreq.y <2, 0.ltoreq.w <2, 0.ltoreq.z <3, and where w, x, y, z is selected such that 1+2w+x-y+z.gtoreq.0 and 2-w-x-y.gtoreq.0.

Even more preferably, according to the invention, the NaSICON structure has formula Na _(1+v) Zr ₂ Si _v P _(3–v) O ₁₂ Wherein v is a real number, wherein 0.ltoreq.v.ltoreq.3. Most preferably v=2.4.

In a preferred embodiment of the partition wall W of the present invention, the ASCs included in the partition wall W have the same structure.

4.1.2 separation element T

According to the invention, the separating element T comprises at least two alkali metal cation-conducting solid ceramic pieces F comprised by the separating wall W _A And F _B Apart, this means that the separation element T is arranged between at least two alkali metal cation conducting solid ceramic pieces comprised by the separation wall W.

The partition wall W comprises suitable partition elements T being any object by means of which the respective ASCs can be arranged separately from each other. The ASC here adjoins the separating element T without play, so that the function of the separating wall in the electrolytic cell E to separate the cathode chamber from the adjacent intermediate chamber or anode chamber in a liquid-tight manner is not impaired.

The shape of the partition element T may be selected by a person skilled in the art depending on the number of ASCs comprised by the partition wall W.

If the partition wall W comprises, for example, two or three ASCs, each of these ASCs may be separated by a platform provided between the ASCs as a partition element T (see fig. 1A).

If the partition wall W comprises four or more ASCs, these ASCs may be separated by a partition element T in the form of a cross (see fig. 1B and 4A) or a grid (see fig. 4B).

It is particularly preferred that the partition wall W comprises at least four ASCs, and even more preferred that the partition elements T are in the form of a cross or grid, as this ensures that all three dimensions of ASCs can be fully thermally expanded/contracted.

The separating element T may be composed of one piece (fig. 2A, 2B). In this case, the ASC is fixed to the separating element without play, for example, using compositions known to the person skilled in the art, for example by means of adhesives, preferably using epoxy resins and phenolic resins. Alternatively or additionally, the separating element T may also be shaped in the following way: the corresponding ASC may be fitted or clamped into the separating element. This can already be carried out in a corresponding manner in the production of the partition wall W (section 4.1.4).

In a preferred embodiment, the partition wall W, in particular between the partition element T and the ASC, comprises a seal Di (fig. 3B, 3C). This ensures that the partition wall W is liquid-tight in a particularly efficient manner. The person skilled in the art can choose the seal Di for the respective ASC or the respective separating element T.

The seal Di comprises in particular a material selected from the group consisting of elastomers, adhesives, preferably elastomers.

Useful elastomers are in particular rubbers, preferably ethylene-propylene-diene rubber ("EPDM"), fluoropolymer rubber ("FPM"), perfluoropolymer rubber ("FFPM") or acrylonitrile-butadiene rubber ("NBR").

In another preferred embodiment, the separation element T comprises at least twoPart T ₁ And T ₂ Said at least two portions T ₁ And T ₂ Can be fixed to each other and thus sandwich the ASC between them.

In this embodiment, it is particularly preferred in this case to install a seal Di between the separating element T and the ASC in order to ensure liquid tightness.

The separation element T preferably comprises a material selected from the group consisting of plastic, glass and wood. More preferably, the separation element T is composed of plastic. Even more preferably, the plastic is selected from polypropylene, polystyrene, polyvinyl chloride, post chlorinated polyvinyl chloride ("PVC-C").

4.1.3 frame element R

In another preferred embodiment, the partition wall W further comprises a frame element R. The frame member R differs from the partition member T in that it is not disposed between the alkali metal cation-conducting solid electrolyte ceramic pieces included in the partition wall W, i.e., does not separate the alkali metal cation-conducting solid electrolyte ceramic pieces from each other. The frame element R in particular defines at least partially, preferably completely, the surface O _KK And O _A/MK . More particularly, this means: the frame element R at least partially, preferably completely surrounds the surface O _KK And O _A/MK 。

The frame element R may or may not be the surface O _KK And O _A/MK Is a part of the same. The frame element R is preferably a surface O _KK And O _A/MK Is a part of the same.

The frame element R can be produced in particular via the surface O _KK And O _A/MK Directly or indirectly, preferably directly.

With respect to the frame element R comprised by the partition wall W, "not directly contactable" means that the frame element R is formed exclusively as not the side face S of the partition wall W _KK And S is _A/MK At least a portion of the surfaces of those sides of (a). More specifically, in this case, the frame element R forms not the side S of the partition wall W _KK And S is _A/MK At least 1%, more preferably at least 25%, more preferably at least 50% of the surface area of the side face of (c) Even more preferably 100%.

With respect to the frame element R comprised by the partition wall W, "directly contactable" means that the surface O _KK And O _A/MK Is formed by the surfaces of the frame elements R, which means that the frame elements R comprised by the dividing wall W are formed at said two surfaces O _KK And O _A/MK Is directly accessible so that it can be moved between the two surfaces O _KK And O _A/MK Where it is wetted, for example with an aqueous solution, an alcoholic solution, an alcohol or water.

This means for the arrangement of the frame elements R in the dividing wall W that there is a lateral side S _KK Surface O on _KK To the side S _A/MK Surface O on _A/MK Is passed completely through the frame element R.

This includes the following embodiments:

-surface O _KK And O _A/MK Is formed by a frame element R (as shown in fig. 4B, 4D);

-surface O _KK And O _A/MK Is entirely formed by the frame element R (as shown in fig. 4A, 4C, 7A, 7B).

The frame element R may additionally form a partition wall W other than the side surface S _KK And S is _A/MK At least a portion of the surfaces of those sides of (a). More particularly, the frame element R forms a non-side S of the partition wall W _KK And S is _A/MK At least 1%, more preferably at least 25%, more preferably at least 50%, even more preferably 100% of the surface area of those sides of (c).

Fig. 4B and 4D show, for example, a case in which the frame member R is formed to be not the side face S of the partition wall W _KK And S is _A/MK Is an embodiment of a portion of the surface of those sides.

Fig. 4A and 4C show, for example, that the frame element R is entirely formed as a non-side S of the partition wall W _KK And S is _A/MK Is disclosed, and the surface of those sides of the substrate is also disclosed.

The frame element R is in particular a material selected from the group consisting of plastic, glass, wood. More preferably, the frame element R is composed of plastic.

Even more preferably, the plastic is selected from polypropylene, polystyrene, polyvinylchloride, PVC-C.

In another preferred embodiment, the frame element R and the separation element T are composed of the same material, and both are even more preferably composed of a plastic, which plastic is even more preferably selected from the group consisting of polypropylene, polystyrene, polyvinylchloride, PVC-C.

The frame element R can be composed of one piece. In this case, the ASC is fixed to the frame element R without play, for example via an adhesive, by means known to the person skilled in the art, with epoxy resins and phenolic resins being particularly suitable. Alternatively or additionally, the frame element R may also be shaped such that the corresponding ASC can be fitted or clamped into the frame element R.

This also means that in a preferred embodiment, in which the partition wall W comprises a frame element R, the ASC, the at least one partition element T and the frame element R abut each other in a gapless manner.

Therefore, there is no aqueous solution or water that can pass through from S between the partition element T, the frame element R and the ASC comprised by the partition wall W _KK Side flow to S _A/MK Side or from S _A/MK Side flow to S _KK Side gap.

Furthermore, especially when the partition wall W comprises a frame element R, wherein the partition element T is at least partly formed in one piece, the frame element R may be composed of at least two parts fixed to each other and clamping the ASC between them. For example, in this case, the partition wall W may have a hinge by which the two portions of the frame element R can be folded open and closed. Furthermore, in this case the partition wall W may have a lock with which the two parts of the frame element R can be locked in place in the folded state (fig. 7A).

In the folded state, the ASC and the separating element T (if it has not been formed in one piece with the frame element R) can be clamped between the frame elements R. In this embodiment, a seal may then be installed between the separating element T and ASC or the frame element R and ASC to ensure liquid tightness.

In a preferred embodiment, at least a portion of the separation element T <17> is formed in one piece with at least a portion of the frame element R <20 >. More specifically, this means that at least a portion of the separation element T is incorporated into the frame element R.

Preferably, the separation element T <17> and the frame element R <20> are present in one piece.

The embodiment of the frame element R has the following advantages: the frame element R may be used as a part of the outer wall in the cell E assembly. The portion of the partition wall W is not in communication with the corresponding interior I _KK 、I _KA Or I _KM Is contacted with the solution in the ceramic part F, thus the part uses a solid electrolyte _A Or F _B Is a waste. In addition, the portion of the partition wall W sandwiched between or forming part of the outer walls is subjected to the brittle solid electrolyte ceramic member F _A Or F _B Unsuitable pressure. Instead, a fracture resistant and cheaper material is therefore chosen for the frame R.

4.1.4 production of partition wall W

The partition wall W may be produced by a method known to those skilled in the art.

For example, the ASC comprised by the partition wall may be inserted into a casting mould, optionally with a seal, and the partition element may be poured by means of a liquid plastic and subsequently cured (injection moulding). During the curing process, the liquid plastic then surrounds the ASC.

Alternatively, the separation element T is cast separately (or partly) and then fixed to the at least two ASCs without gaps (e.g. by adhesive connection).

4.2 electrolytic cell E

The partition wall W of the present invention is suitable as a partition wall in the electrolytic cell E according to the first aspect of the present invention.

Thus, in a first aspect, the invention relates to an electrolytic cell E comprising

At least one anode chamber K _A Having at least one inlet Z _KA At least one outlet A _KA Including anode E _A Internal I of (2) _KA ，

At least one cathodic compartment K _K Having at least one inlet Z _KK At least one outlet A _KK Including a cathode E _K Internal I of (2) _KK ，

-and at least one intermediate chamber K interposed _M Having at least one inlet Z _KM At least one outlet A _KM And internal I _KM ，

Wherein I is _KA And I _KM Separated from each other by diffusion barrier D and a _KM Via the connecting piece V _AM Is connected to inlet Z _KA So that liquid can pass through the connecting piece V _AM From I _KM Delivery to I _KA ，

Wherein the method comprises the steps of

-I _KK And I _KM Separated from each other by the partition wall W of the present invention,

it is characterized in that

The partition wall W comprises an alkali metal cation-conducting solid ceramic part and in particular also a partition element T via a surface O _KK On the side S _KK Upper direct contact internal I _KK ，

And is also provided with

The partition wall W comprises an alkali metal cation-conducting solid ceramic part and in particular also a partition element T via a surface O _A/MK On the side S _A/MK Upper direct contact internal I _KM 。

The electrolytic cell E in the first aspect of the invention comprises at least one anode chamber K _A At least one cathode chamber K _K And at least one intermediate chamber K arranged in between _M . This also includes having more than one anode chamber K _A And/or cathode chamber K _K And/or intermediate chamber K _M Is a cell E of the above-mentioned equipment. Such electrolytic cells are described, for example, in DD 258 A3 and US 2006/0226022 A1, wherein the chambers are joined to one another in the form of modules.

In a preferred embodiment, the cell E of the first aspect of the invention comprises an anode chamber K _A And a cathode chamber K _K And optionally an intermediate chamber K _M 。

The electrolytic cell E generally has an outer wall W _A . Outer wall W _A In particular from a material selected from the group consisting of steel (preferably rubberized steel), plastic (in particular(thermosetting polydicyclopentadiene)), PVC (polyvinyl chloride), PVC-C (post-chlorinated polyvinyl chloride), PVDF (polyvinylidene fluoride). W (W) _A In particular may be perforated for inlet and outlet. At W _A Inside is said at least one anode chamber K _A Said at least one cathode chamber K _K . In the embodiment described, in which the electrolytic cell E comprises one of said at least one intermediate chamber K _M 。

_K 4.2.1 cathode Chamber K

Cathode chamber K _K Having at least one inlet Z _KK At least one outlet A _KK Including a cathode E _K Internal I of (2) _KK 。

Cathode chamber K _K Internal I of (2) _KK And intermediate chamber K _M Internal I of (2) _KM Separated by the partition wall W of the present invention.

4.2.1.1 cathode E _K

Cathode chamber K _K Including internal I _KK Internal I _KK And further comprises a cathode E _K . Useful such cathodes E _K Is any electrode familiar to the person skilled in the art which is stable under the conditions of the method according to the invention of the second aspect of the invention. These electrodes are described in particular in WO 2014/008410 A1 [025 ]]Paragraph or DE 10360758 A1 [030 ]]In the section. The electrode E _K May be selected from the group consisting of reticulated hairs, three-dimensional matrix structures, and "balls". Cathode E _K In particular comprising a material selected from the group consisting of steel, nickel, copper, platinum, platinized metal, palladium, carbon supported palladium, titanium. Preferably E _K Comprising nickel.

In an embodiment of the electrolytic cell E according to the first aspect of the invention, wherein the electrolytic cell E comprises an intermediate chamber K _M Which is located in the anode chamber K _A And cathode chamber K _K Between them.

4.2.1.2 entrance Z _KK And outlet A _KK

Cathode chamber K _K Also comprises an inlet Z _KK And outlet A _KK . This ensures that the liquid (e.g. solution L ₂ ) Added to the cathode chamber K _K Internal I of (2) _KK And removing the liquid present therein (e.g. solution L ₁ ). Inlet Z _KK And outlet A _KK Here attached to the cathode chamber K in the following manner _K : so that the liquid flows through the cathode chamber K _K Internal I of (2) _KK Time and cathode E _K And (3) contact. This is the case when, in carrying out the process according to the invention in the second aspect of the invention, the solution L of the alkali metal alkoxide XOR in the alcohol ROH ₂ Transported through cathode chamber K _K Internal I of (2) _KK At outlet A _KK Obtaining solution L ₁ Is a necessary condition of (2).

Inlet Z _KK And outlet A _KK May be attached to the electrolytic cell E by methods known to the person skilled in the art, for example by means of holes in the outer wall and corresponding connectors (valves) that simplify the introduction and discharge of the liquid.

_A 4.2.2 anode Chamber K

Anode chamber K _A Having at least one inlet Z _KA At least one outlet A _KA Including anode E _A Internal I of (2) _KA 。

Anode chamber K _A Internal I of (2) _KA And intermediate chamber K _M Internal I of (2) _KM Separated by a diffusion barrier D.

4.2.2.1 Anode E _A

Anode chamber K _A Including internal I _KA Internal I _KA And further comprises an anode E _A . Useful such anodes E _A Is any electrode familiar to the person skilled in the art which is stable under the conditions of the method according to the invention of the second aspect of the invention. These electrodes are described in particular in WO 2014/008410 A1 [024 ]]Paragraph or DE 10360758 A1 [031 ]]In the section. The electrode E _A May be composed of one layer or of a plurality of planar layers parallel to each other, each layer may bePerforated or porous. Anode E _A Especially containing a load such as titanium or(an iron/nickel/cobalt alloy in which the respective components are preferably as follows: 54 mass% iron, 29 mass% nickel, 17 mass% cobalt) of a material selected from the group consisting of: ruthenium oxide, iridium oxide, nickel, cobalt, nickel tungstate, nickel titanate, noble metals such as, in particular, platinum. Other possible anode materials are, inter alia, stainless steel, lead, graphite, tungsten carbide, titanium diboride. Preferably, anode E _A Comprising a titanium anode (RuO) coated with ruthenium oxide/iridium oxide ₂ +IrO ₂ /Ti)。

4.2.2.2 entrance Z _KA And outlet A _KA

Anode chamber K _K Also comprises an inlet Z _KA And outlet A _KA . This enables the liquid (e.g. solution L ₃ ) Added to the cathode chamber K _A Internal I of (2) _KA And removing the liquid present therein (e.g. solution L ₄ ). Inlet Z _KA And outlet A _KA Here attached to the anode chamber K in the following manner _A : so that the liquid flows through the anode chamber K _A Internal I of (2) _KA Time and anode E _A And (3) contact. This is the case when the solution L of the salt S is in the process according to the invention in carrying out the second aspect of the invention ₃ Conveyed through anode chamber K _A Internal I of (2) _KA At outlet A _KA Obtaining solution L ₄ Is a necessary condition of (2).

Inlet Z _KA And outlet A _KA May be attached to the electrolytic cell E by methods known to the person skilled in the art, for example by means of holes in the outer wall and corresponding connectors (valves) that simplify the introduction and discharge of the liquid. In a particular embodiment, inlet Z _KA Or may be located within the cell, for example in the form of perforations in the diffusion barrier D.

_M 4.2.3 intermediate Chamber K

In a first aspect of the invention the electrolytic cell E has at least one intermediate chamber K _M . Intermediate chamber K _M Is positioned in the cathode chamber K _K And anode chamber K _A Between them. It comprises at least one inlet Z _KM At least one outlet A _KM And internal I _KM 。

Anode chamber K _A Internal I of (2) _KA Through diffusion barrier D and intermediate chamber K _M Internal I of (2) _KM And (5) separating. A is that _KM Then also via the connecting piece V _AM Is connected to inlet Z _KA So that liquid can pass through the connecting piece V _AM From I _KM Guide to I _KA Is a kind of medium.

4.2.3.1 diffusion barrier D

Intermediate chamber K _M Internal I of (2) _KM Through diffusion barrier D and anode chamber K _A Internal I of (2) _KA Separated from the cathode chamber K by a partition wall W _K Internal I of (2) _KK And (5) separating.

The material used for the diffusion barrier layer D may be in the second aspect of the invention stable under the conditions of the method according to the invention and prevent or slow down protons from being present in the anode chamber K _A Internal I of (2) _KA Is directed to the intermediate chamber K _M Internal I of (2) _KM Any material transferred.

The diffusion barrier D used is in particular a non-ion-specific partition wall or a membrane permeable to specific ions. The diffusion barrier D is preferably a non-ion specific partition wall.

The material of the non-ion specific separation wall is selected in particular from: fabrics, in particular woven fabrics or metal braids; glass, in particular sintered glass or frit; ceramics, in particular ceramic materials; the membrane separator, and more preferably a woven fabric or a metal braid, particularly preferably a woven fabric. The woven fabric preferably comprises a plastic, more preferably a plastic selected from the group consisting of PVC, PVC-C, polyvinyl ether ("PVE"), polytetrafluoroethylene ("PTFE").

If the diffusion barrier D is a "specific ion permeable membrane", this means that the corresponding membrane promotes the diffusion of specific ions therethrough relative to other ions according to the invention. More specifically, this means that the membrane promotes the diffusion of ions of a particular charge type therethrough relative to ions of opposite charge. Even more preferably, the particular ion permeable membrane also facilitates diffusion of ions of a particular one of the charge types therethrough relative to other ions of the same charge type.

If the diffusion barrier D is a "specific ion permeable membrane", the diffusion barrier D is in particular an anion-or cation-conducting membrane.

According to the invention, anion-conducting membranes are those which selectively conduct anions, preferably specific anions. In other words, they promote the diffusion of anions therethrough with respect to cations, in particular with respect to protons; even more preferably, they additionally promote the diffusion of specific anions therethrough relative to the diffusion of other anions therethrough.

Cation-conducting membranes according to the invention are those membranes which selectively conduct cations, preferably specific cations. In other words, these membranes promote the diffusion of cations therethrough relative to anions; even more preferably, these membranes additionally promote the diffusion of specific cations therethrough relative to the diffusion of other cations therethrough; more preferably, these membranes also promote the diffusion of cations other than protons, more preferably sodium cations, therethrough relative to protons.

"promote diffusion of a particular ion X relative to diffusion of other ions Y" more specifically refers to the diffusion coefficient (unit: m) of the ion type X at a given temperature for the film in question ² S) is 10 times, preferably 100 times, preferably 1000 times the diffusion coefficient of the ion type Y for the membrane in question.

If the diffusion barrier D is a "specific ion permeable membrane", it is preferably an anion conducting membrane, since this is particularly effective in preventing protons from the anode chamber K _A Diffusion into intermediate chamber K _M And (3) inner part.

The anion-conducting membranes used are in particular anion-conducting membranes which are selective for the anions comprised by the salt S. Such films are known to and can be used by those skilled in the art.

The salt S is preferably a halide, sulfate, sulfite, nitrate, bicarbonate or carbonate of X, even more preferably a halide.

The halide includes fluoride, chloride, bromide and iodide. The most preferred halide is chloride.

The anion-conducting membrane used is preferably an anion-conducting membrane which is selective for halides, preferably chlorides.

Anion-conducting membranes are described, for example, in: M.A.Hickner, A.M.Herring, E.B.Coughlin, journal of Polymer Science, part B Polymer Physics 2013,51,1727-1735; C.G.Arges, V.Ramani, P.N.Pintauro, electrochemical Society Interface 2010,19,31-35; WO 2007/048712 A2; volkmar M.Schmidt, elektrochemische Verfahrenstechnik, grundlagen, refetinstechnik, prozessoptimierung textbook page 181 [ Electrochemical Engineering, fundamentals, reaction Technology, process Optimization ], version 1 (10 months, 8 2003).

Thus, even more preferably, the anion-conducting membranes used are in particular organic polymers selected from the group consisting of polyethylene, polybenzimidazole, polyetherketone, polystyrene, polypropylene, and fluorinated membranes such as polyperfluoroethylene, preferably polystyrene, wherein these have a molecular structure selected from the group consisting of-NH ₃ ⁺ 、-NRH ₂ ⁺ 、-NR ₃ ⁺ 、＝NR ⁺ 、-PR ₃ ⁺ Wherein R is an alkyl group preferably having 1 to 20 carbon atoms or other cationic group. They preferably have a radical selected from the group consisting of-NH ₃ ⁺ 、-NRH ₂ ⁺ and-NR ₃ ⁺ More preferably selected from-NH ₃ ⁺ and-NR ₃ ⁺ Even more preferably NR ₃ ⁺ Is a covalent bond of a functional group.

If the diffusion barrier D is a cation-conducting membrane, it is in particular a membrane that is selective for the cations comprised by the salt S. Even more preferably, the diffusion barrier D is an alkali metal cation conducting membrane, even more preferably a potassium and/or sodium ion conducting membrane, most preferably a sodium ion conducting membrane.

For example, a cation-conducting membrane is described on page 181 of Volkmar M.Schmidt textbook Elektrochemische Verfahrenstechnik: grundlagen, refaktiontechnik, prozessoptimal rug, 1 st edition (10/8/2003).

Thus, even more preferably, the cation-conducting membranes used are in particular organic polymers selected from the group consisting of polyethylene, polybenzimidazole, polyetherketone, polystyrene, polypropylene, and fluorinated membranes such as polyperfluoroethylene, preferably polystyrene and polyperfluoroethylene, wherein these bear covalently bonded functional groups selected from the group consisting of: -SO ₃ ^- 、-COO ^- 、-PO ₃ ^2- and-PO ₂ H ^- preferably-SO ₃ ^- (described in DE 10 2010 062804A1, U.S. Pat. No. 3,182).

This may be, for example, sulfonated poly-perfluoroethylene @CAS number: 31175-20-9). These are known to those skilled in the art, for example, from WO 2008/076327 A1 ([ 058 ]]Paragraph), US 2010/0044242A1 ([ 042 ]]Paragraph) or U.S. Pat. No. 5,0204459 A1 and can be given the trade name +.>F、Are commercially available.Films are described, for example, in S.A.Mareev, D.Yu.Butylskii, N.D.Pismenskaya, C.Larchet, L.Dammak, V.V.Nikonenko, journal of Membrane Science 2018,563,768-776.

If a cation-conducting membrane is used as diffusion barrier D, it can be, for example, a polymer functionalized with sulfonic acid groups, in particular of the formula P _NAFION Wherein n and m may independently be 1 to 10 ⁶ Is preferably 10 to 10 ⁵ More preferably 10 ² To 10 ⁴ Is an integer of (a).

4.2.3.2 entrance Z _KM And outlet A _KM

Intermediate chamber K _M Also comprises an inlet Z _KM And outlet A _KM . This enables the liquid (e.g. solution L ₃ ) Added to the intermediate chamber K _M Internal I of (2) _KM And the liquid present therein (e.g. solution L ₃ ) Transferred to anode chamber K _A 。

Inlet Z _KM And outlet A _KM May be attached to the electrolytic cell E by methods known to the person skilled in the art, for example by means of holes in the outer wall and corresponding connectors (valves) that simplify the introduction and discharge of the liquid. Outlet A _KM Or may be located within the cell, for example in the form of perforations in the diffusion barrier D.

4.2.3.3 connector V _AM

In the electrolytic cell E according to the first aspect of the invention, the outlet A _KM Through the connecting piece V _AM Is connected to the inlet Z in the following manner _KA : so that liquid can pass through the connecting piece V _AM From I _KM Guide to I _KA Is a kind of medium.

Connecting piece V _AM May be formed inside and/or outside the electrolytic cell E, and is preferably formed inside the electrolytic cell E.

1) If the connecting piece V _AM Formed within the electrolytic cell E, it is preferably formed by at least one perforation in the diffusion barrier D. This embodiment is particularly preferred when the diffusion barrier layer D used is a non-ion specific partition wall, in particular a metal braid or woven fabric. This acts as a diffusion barrier D and, due to the braiding properties, has the effect of acting as a connection V from the beginning _AM Perforation and clearance of action.

2) The embodiments described below are preferred, in particular when the diffusion barrier D used is a membrane permeable to specific ions: in this embodiment, the connection member V _AM Formed outside the electrolytic cell E, preferably by A extending outside the electrolytic cell E _KM And Z _KA Formed, in particular, through the outer wall W _A Outlet A of (2) _KM From the interior I of the intermediate chamber _KM Is preferably formed in the intermediate chamber K _M At the bottom of (a), inlet Z _KM More preferably in the intermediate chamber K _M At the top end of (d) and pass through the outer wall W _A Inlet Z of (2) _KA In the anode chamber K _A Is formed at the interior of the anode chamber K _A And these are connected by a conduit (e.g. a pipe or hose), said conduit preferably comprising a material selected from rubber and plastic. Outlet A _KA Then more preferably in the anode chamber K _A At the top end of (2).

"Outlet A _KM In the intermediate chamber K _M "at the bottom of (C)" means outlet A _KM Attached to cell E in the following manner: so that solution L ₃ Leave the intermediate chamber K in the direction of gravity _M 。

"inlet Z _KA In the anode chamber K _A Refers to inlet Z _KA Attached to cell E in the following manner: so that solution L ₃ Against gravity into anode chamber K _A 。

"inlet Z _KM In the intermediate chamber K _M At the top of (a) refers to inlet Z _KM Attached to cell E in the following manner: so that solution L ₃ Into the intermediate chamber K in the direction of gravity _M 。

"Outlet A _KA In the anode chamber K _A At the top of (a) refers to outlet A _KA Is mounted on the electrolytic cell E in the following manner: so that solution L ₄ Leave anode chamber K against gravity _A 。

When outlet A _KM From in the intermediate chamber K _M An outer wall W at the bottom of (2) _A Formed and inlet Z _KA From the anode chamber K _A An outer wall W at the bottom of (2) _A This embodiment is particularly advantageous and therefore preferred when formed. This arrangement makes it possible in a particularly simple manner to recover from the L-shaped profile ₄ Anode chamber K of (1) _A Is removed in the anode chamber K _A To separate them further.

When forming the connection member V outside the electrolytic cell E _AM When in particular Z _KM And A _KM Arranged in the intermediate chamber K _M Is arranged on the outer wall W of _A Opposite ends (i.e. Z, for example) _KM At the bottom of the electrolytic cell E, A _KM At the top end of the electrolytic cell E, or vice versa) and will Z _KA And A _KA Arranged in the anode chamber K _A Is arranged on the outer wall W of _A Opposite ends (i.e. Z _KA At the bottom of the electrolytic cell E, A _KA At the top end of the electrolytic cell E or vice versa), more particularly as shown in fig. 6A. By virtue of this geometry, L ₃ Must flow through K _M And K _A These two chambers. Here, Z _KA And Z _KM May be formed on the same side of the electrolytic cell E, in which case A _KM And A _KA Is also automatically formed on the same side of the electrolytic cell E. Alternatively, Z _KA And Z _KM May be formed on opposite sides of the electrolytic cell E, in which case A _KM And A _KA Automatically formed on the opposite side of the electrolytic cell E.

3) When the connecting piece V _AM When formed in the electrolytic cell E, this can be achieved in particular by having one side of the electrolytic cell E ("A side") comprise the inlet Z _KM And outlet A _KA The side is realized as the top or bottom of the electrolytic cell E, preferably as shown in fig. 6B, and the diffusion barrier D extends into the electrolytic cell E from this side ("a side") but does not reach the side of the electrolytic cell E opposite to the a side ("B side"), i.e. the bottom or top of the electrolytic cell E while covering 50% or more of the height of the three-compartment cell E, preferably 60% to 99% of the height of the three-compartment cell E, more preferably 70% to 95% of the height of the three-compartment cell E, even more preferably 80% to 90% of the height of the three-compartment cell E, still more preferably 85% of the height of the three-compartment cell E. Since diffusion barrier D does not contact the B side of triple cell E, the diffusion barrier D is in contact with the outer wall W of the B side of triple cell E _A Creating a gap therebetween. In this case, the gap is the connection member V _AM . By virtue of this geometry, L ₃ Must flow completely through K _M And K _A These two chambers.

These embodimentsBest ensure the saline solution L ₃ At the anode E _A Flows through an acid-sensitive solid electrolyte prior to contact, which results in the formation of an acid.

According to the invention, the "bottom of cell E" is the side of cell E: solution (e.g. A in FIG. 6A _KM In the case of L ₃ ) Through which it exits from the cell E in the same direction as gravity, or the side of the cell E: the solution (e.g. Z in FIGS. 6A and 6B _KK In the case of L ₂ ) Through which the counter gravity is fed to the electrolytic cell E.

According to the invention, the "top end of the cell E" is the side of the cell E: solutions (e.g. A in FIGS. 6A and 6B) _KA In the case of L ₄ ，A _KK In the case of L ₁ ) Through which the counter-gravity exits from the cell E, or the side of the cell E: the solution (e.g. Z in FIGS. 6A and 6B _KM In the case of L ₃ ) Through which it is fed to the electrolytic cell E in the same direction as gravity.

4.2.4 arrangement of dividing wall W in electrolytic cell E

The partition wall W is arranged in the electrolytic cell E in the following manner: so that the partition wall W comprises an alkali metal cation conducting solid electrolyte ceramic member and preferably also a partition element T via a surface O _KK On the side S _KK Upper direct contact internal I _KK 。

This means that the dividing wall W is arranged in the electrolytic cell E such that when the side S _KK Internal I on side _KK With solution L entirely ₂ When filling, solution L ₂ Then via surface O _KK In contact with all alkali metal cation conducting solid electrolyte ceramic pieces comprised by the partition wall W and preferably also the partition element T, so that ions (e.g. alkali metal ions, such as sodium, lithium) from all ASCs comprised by the partition wall W can enter the solution L ₂ 。

Furthermore, the partition wall W is arranged in the electrolytic cell E such that the alkali metal cation conducting solid electrolyte ceramic member comprised by the partition wall W and preferably also the partition element T pass through the meter Surface O _A/MK On the side S _A/MK Upper direct contact internal I _KM 。

This means: the partition wall W adjoins the intermediate chamber K _M Internal I of (2) _KM . In these embodiments, the dividing wall W is arranged within the electrolytic cell E such that when the side S _AM/K Internal I on _KM Completely filled with solution L ₃ At the time, solution L ₃ Then via surface O _A/MK In contact with all the alkali metal cation conducting solid electrolyte ceramic pieces comprised by the partition wall W and preferably also the partition element T, such that a solution L is derived ₃ Ions (e.g., sodium, lithium, alkali metal ions) may enter any ASC included in the partition wall W.

In a preferred embodiment of the electrolytic cell E of the first aspect of the invention, the portion of the surface O formed by ASC _KK At least 50%, in particular at least 70%, preferably at least 90%, most preferably 100% of the total I _KK And (3) contact.

In a preferred embodiment of the electrolytic cell E having at least one intermediate chamber in the first aspect of the invention, the portion of the surface O formed by ASC _A/MK At least 50%, in particular at least 70%, preferably at least 90%, most preferably 100% of the total I _KM And (3) contact.

4.3 method according to the invention

In a second aspect, the invention relates to a process for producing a solution L of an alkali metal alkoxide XOR in an alcohol ROH ₁ Wherein X is an alkali metal cation and R is an alkyl group having 1 to 4 carbon atoms. The method according to the second aspect of the invention is carried out in the electrolytic cell E of the first aspect of the invention.

X is preferably selected from Li ⁺ 、K ⁺ 、Na ⁺ More preferably from K ⁺ 、Na ⁺ . Most preferably, X is Na ⁺ 。

R is preferably selected from the group consisting of n-propyl, isopropyl, ethyl and methyl, more preferably from the group consisting of ethyl and methyl. R is most preferably methyl.

According to the invention, the electrolytic cell E comprises at least one intermediate chamber K _M And go throughSteps (β1), (β2) and (β3) are performed simultaneously.

4.3.1 step (. Beta.1)

In step (. Beta.1), a solution L comprising an alcohol ROH, preferably comprising an alkali metal alkoxide XOR and an alcohol ROH ₂ Transport through K _K 。

Solution L ₂ Preferably free of water. According to the invention, "free of water" means based on solution L ₂ Weight of medium alcohol ROH, solution L ₂ The weight (mass ratio) of the reclaimed water is less than or equal to 1:10, more preferably less than or equal to 1:20, even more preferably less than or equal to 1:100, even more preferably less than or equal to 0.5:100.

If solution L ₂ Containing XOR, based on the whole solution L ₂ Solution L ₂ Mass ratio of medium XOR especially>From 0 wt% to 30 wt%, preferably from 5 wt% to 20 wt%, more preferably from 10 wt% to 15 wt%, most preferably from 13 wt% to 14 wt%, most preferably 13 wt%.

If solution L ₂ Containing XOR, solution L ₂ The mass ratio of medium XOR to alcohol ROH is in particular in the range of 1:100 to 1:5, more preferably in the range of 1:25 to 3:20, even more preferably in the range of 1:12 to 1:8, even more preferably 1:10.

4.3.2 step (. Beta.2)

In step (. Beta.2), a neutral or alkaline aqueous solution L of a salt S containing X as a cation is added ₃ Transport through K _M Then via V _AM Then pass through K _A 。

Aqueous solution L ₃ The pH of (C) is not less than 7.0, preferably in the range of 7 to 12, more preferably in the range of 8 to 11, even more preferably 10 to 11, most preferably 10.5.

Based on the whole solution L ₃ Solution L ₃ Middle salt SThe mass ratio of (2) is preferably in>From 0 wt% to 20 wt%, preferably from 1 wt% to 20 wt%, more preferably from 5 wt% to 20 wt%, even more preferably from 10 wt% to 20 wt%, most preferably 20 wt%.

4.3.3 step (. Beta.3)

In step (. Beta.3), then in E _A And E is _K Between which a voltage is applied.

This causes a current to be transferred from the charging source to the anode, transferring charge via ions to the cathode, and eventually transferring the current back to the charging source. Charging sources are known to those skilled in the art and are generally rectifiers which convert alternating current into direct current and which can produce a specific voltage via a transformer.

This in turn produces the following results:

at outlet A _KK Obtaining solution L ₁ Wherein L is ₁ The XOR concentration in (a) is higher than L ₂ The concentration of the XOR in (a),

at outlet A _KA Obtaining an aqueous solution L of S ₄ Wherein L is ₄ In S concentration lower than L ₃ S concentration in (b).

In step (β3) of the method according to the second aspect of the invention, in particular, such a voltage is applied that such a current flows that the current density (=current supplied to the electrolytic cell and contact is present in the intermediate chamber K) _M The ratio of the area of the solid electrolyte of the anolyte) is 10 to 8000A/m ² More preferably in the range of 100 to 2000A/m ² In the range of from 300 to 800A/m, even more preferably ² Within a range of (2), and more preferably 494A/m ² . This can be determined in a standard manner by a person skilled in the art. The contact being present in the intermediate chamber K _M The area of the solid electrolyte of the anolyte in (a) is in particular 0.00001 to 10m ² Preferably 0.0001 to 2.5m ² More preferably 0.0002 to 0.15m ² Even more preferably 2.83cm ² 。

Obviously, when K _M And K _A The two chambers are at least partially loaded with L ₃ And K is _K At least partially is loaded with L ₂ When step (β3) of the method according to the second aspect of the invention is performed, so that L ₃ And L ₂ Both in contact with the solid electrolyte comprised by the partition wall W and in particular also with the partition element T.

In step (. Beta.3) in E _A And E is _K The fact that charge transfer occurs between them suggests K _K 、K _M And K _A Loaded with L at the same time ₂ And L ₃ So that they cover the electrode E _A And E is _K To the extent that the circuit is complete.

When L is to ₃ Is continuously conveyed through K _M 、V _AM And K _A And L is ₂ Is continuously conveyed through K _K This is especially the case when, and L ₃ Is arranged to cover electrode E _A And L is ₂ At least partially, preferably completely, covering the electrode E _K 。

In another preferred embodiment, the method according to the second aspect of the invention is performed continuously, i.e. step (β1) and step (β2) are performed continuously, while applying a voltage according to step (β3).

After performing step (. Beta.3), at outlet A _KK Obtaining solution L ₁ Wherein L is ₁ The XOR concentration in (a) is higher than L ₂ XOR concentration in (a). If L ₂ Having included XOR, L ₁ The XOR concentration in (a) is preferably L ₂ From 1.01 to 2.2 times, more preferably from 1.04 to 1.8 times, even more preferably from 1.077 to 1.4 times, even more preferably from 1.077 to 1.08 times, most preferably L ₂ 1.077 times the XOR concentration in (1.077), where L ₁ And L ₂ The mass proportion of the medium XOR is more preferably in the range of 10 to 20 wt.%, even more preferably 13 to 14 wt.%.

Aqueous solution L ₃ The cation X concentration in (2) is preferably in the range of 3.5 to 5mol/l, more preferably 4mol/l. Aqueous solution L ₄ The concentration of the cation X in (B) is more preferably higher than that in (C)The aqueous solutions L used in each case ₃ The concentration of the cation X in the catalyst is 0.5mol/l lower.

More particularly, steps (β1) to (β3) of the process according to the second aspect of the invention are carried out at a temperature of from 20 ℃ to 70 ℃, preferably from 35 ℃ to 65 ℃, more preferably from 35 ℃ to 60 ℃, even more preferably from 35 ℃ to 50 ℃ and a pressure of from 0.5 bar to 1.5 bar, preferably from 0.9 bar to 1.1 bar, more preferably 1.0 bar.

In carrying out steps (. Beta.1) to (. Beta.3) of the method according to the second aspect of the invention, the cathode chamber K is generally _K Hydrogen gas is formed in the reactor, and the hydrogen gas can be mixed with the solution L ₁ Together via outlet A _KK Removed from the pool. In a particular embodiment of the invention, hydrogen and the solution L may then be reacted by methods known to the person skilled in the art ₁ Is separated from the mixture of (a). When the alkali metal compound used is a halide, especially a chloride, it is possible to provide a reaction in the anode chamber _KA Chlorine or other halogen gas is formed and can be mixed with the solution L ₄ Together via outlet A _KK Removed from the pool. In addition, oxygen and/or carbon dioxide may also be formed, which may likewise be removed. In a particular embodiment of the invention, chlorine, oxygen and/or CO may then be reacted by methods known to the person skilled in the art ₂ Is mixed with solution L ₄ And (5) separating. Can also be used for the treatment of chlorine, oxygen and/or CO ₂ Gas and solution L ₄ After separation, these gases are separated by methods known to those skilled in the art.

Other advantages of 4.3.4 steps (. Beta.1) to (. Beta.3)

This execution of steps (β1) to (β3) brings unexpected advantages which were unexpected according to the prior art. Steps (β1) to (β3) of the method according to the invention protect the acid-sensitive solid electrolyte from corrosion without sacrificing alkoxide solution from the cathodic space as buffer solution as in the prior art. The process according to the invention is therefore more efficient than the procedure described in WO 2008/076327 A1, in which WO 2008/076327 A1 the product solution is used in the intermediate chamber, which reduces the overall conversion.

5. Examples

5.1 comparative example 1

Sodium Methoxide (SM) was produced by a cathodic process, in which a 20 wt% NaCl solution (in water) was supplied in the anode chamber and a 10 wt% sodium methoxide methanol solution was supplied in the cathode chamber. The cell consists of three chambers corresponding to the chambers shown in fig. 1B. The connection between the intermediate chamber and the anode chamber is established by means of a hose mounted at the bottom of the electrolytic cell. The anode chamber and the intermediate chamber are composed of 2.83cm ² Is separated by an anion exchange membrane (Tokuyama AMX, ammonium groups on the polymer). The cathode chamber and the intermediate chamber have a cross-sectional area of 2.83cm ² Is divided by a NaSICON type ceramic. The ceramic has Na _3.4 Zr _2.0 Si _2.4 P _0.6 O ₁₂ Is a chemical composition of (a) a (b).

The anolyte is transferred to the anode chamber through the intermediate chamber. The flow rate of the anolyte was 1 liter/hour, the flow rate of the catholyte was 90 milliliters/hour, and a current of 0.14A was applied. The temperature was 35 ℃. Electrolysis was carried out at a constant voltage of 5V for 500 hours.

It was found that a pH gradient was built up in the intermediate chamber over a longer period of time, due to the diffusion of protons formed during the electrolytic process where the ions migrate to the electrode and the anode are in further reaction. Such a local increase in pH is undesirable because it can attack the solid electrolyte and can lead to corrosion and cracking of the solid electrolyte, especially in the case of prolonged operation.

In addition, naSICON ceramics expand and contract due to heating and cooling effects when the cell is repeatedly started and shut down. Furthermore, naSICON membranes may move within the cell. This is problematic because the propensity for ceramic cracking increases and can result in electrolyte leakage from the intermediate chamber into the cathode chamber, which can dilute the electrolysis product. In addition, this causes leakage of the cell outer wall, thereby causing leakage of the electrolyte to the outside.

5.2 comparative example 2

Comparative example 1 was repeated using a two-chamber cell comprising only one anode chamber and one cathode chamber, wherein the anode chamber and the cathode chamber were separated by a NaSICON-type ceramic (fig. 1A). Thus, the cell does not comprise any intermediate chamber. This reflects an even faster corrosion of the ceramic compared to comparative example 1, which results in a rapid rise of the voltage curve. At an initial voltage value <5V, the voltage rises to >20V within 100 hours.

5.3 example 1 of the invention

Comparative example 1 was repeated using an electrolytic cell according to fig. 6A, in which a partition wall comprising two NaSICON ceramic pieces in a frame was inserted.

This arrangement reduces the extent of the expansion and contraction process, which contributes to the service life of the ceramic part and results in a purer product solution due to leakage prevention.

5.4 example 2 of the invention

Comparative example 2 was repeated using an electrolytic cell according to fig. 6A, in which partition walls comprising four NaSICON ceramic pieces in a frame were inserted, wherein a frame element R was combined with a partition element T (fig. 7A, but without a hinge and without a lock).

5.5 results

The relaxation of the tension within the ASC by the expansion and contraction process with repeated electrolysis cycles results in an extended electrolysis chamber life. In the implementation according to embodiments 1 and 2 of the present invention, these effects are reduced, which increases the stability of the solid electrolyte.

The use of the three-compartment cell according to the invention in the method according to the invention also prevents corrosion of the solid electrolyte without sacrificing the alkali metal alkoxide product for the intermediate compartment and the voltage is kept constant. These advantages, which have been evident from a comparison of these two comparative examples 1 and 2, emphasize the surprising effect of the electrolytic cell with intermediate chamber and the corresponding method carried out therein.

6. Reference numerals

Claims

1. An electrolytic cell E <1>, comprising:

At least one cathode chamber K _K <12>Having at least one inlet Z _KK <120>At least one outlet A _KK <121>Comprising a cathode E _K <123>Internal I of (2) _KK <122>，

And at least one intermediate chamber K arranged in between _M <13>Having at least one inlet Z _KM <130>At least one outlet A _KM <131>And internal I _KM <132>，

Wherein I is _KA <112>And I _KM <132>Through diffusion barrier layer D<14>Apart from each other,

And A is _KM <131>Through the connecting piece V _AM <15>Is connected to inlet Z _KA <110>So that the liquid can pass through the connecting piece V _AM <15>From I _KM <132>Enter I _KA <112>，

Wherein I is _KK <122>And I _KM <132>Through the partition wall W<16>Separated from each other, the partition wall W<16>Comprising a surface O _KK <163>Side S of (2) _KK <161>And the side S _KK <161>Opposite has a surface O _A/MK <164>Side S of (2) _A/MK <162>，

Wherein the partition wall W<16>Comprising at least two alkali metal cation-conducting solid electrolyte ceramic pieces F _A <18>And F _B <19>The ceramic part is passed through at least one separating element T<17>Separated from each other in the following manner: so that the partition wall W<16>The included alkali metal cation conducting solid electrolyte ceramic piece is via surface O _KK <163>Via surface O _A/MK <164>Both of which are directly accessible and,

it is characterized in that

The partition wall W<16>The included alkali metal cation conducting solid ceramic member passes through surface O _KK <163>On the side S _KK <161>Upper direct contact internal I _KK <122>And the partition wall W<16>The included alkali metal cation conducting solid electrolyte ceramic piece is via surface O _A/MK <164>On the side S _A/MK <162>Upper direct contact internal I _KM <132>。

2. Cell E according to claim 1<1>Wherein the partition wall W<16>Comprising at least four alkali metal cation conducting solid electrolyte ceramic members F _A <18>、F _B <19>、F _C <28>And F _D <29>。

3. The electrolytic cell E <1> according to claim 2, wherein the separation element T <17> takes the form of a cross or a grid.

4. A cell E <1> according to any one of claims 1 to 3, wherein the separation element T <17> comprises a material selected from plastics, glass, wood.

5. The electrolytic cell E <1> according to any one of claims 1 to 4, wherein the partition wall W <16> comprises a frame element R <20>.

6. The electrolytic cell E <1> according to claim 5, wherein at least a portion of the dividing element T <17> is present in a unitary form with at least a portion of the frame element R <20>.

7. The electrolytic cell E <1> according to any one of claims 1 to 6, wherein the alkali metal cation conducting solid electrolyte ceramic member comprised by the partition wall W <16> independently has a structure of the formula:

M ^I _1+2w+x-y+z M ^II _w M ^III _x Zr ^IV _2-w-x-y M ^V _y (SiO ₄ ) _z (PO ₄ ) _3-z

wherein M is ^I Selected from Na ⁺ 、Li ⁺ ，

M ^II Is a divalent metal cation, and is preferably a divalent metal cation,

M ^III is a cation of a trivalent metal, and is a cation of a trivalent metal,

M ^V is a pentavalent metal cation, and is a pentavalent metal cation,

roman index I, II, III, IV, V indicates how oxidized the corresponding metal cation is present,

and w, x, y, z is a real number, wherein 0.ltoreq.x <2, 0.ltoreq.y <2, 0.ltoreq.w <2, 0.ltoreq.z <3,

and wherein w, x, y, z is selected such that 1+2w+x-y+z is greater than or equal to 0 and 2-w-x-y is greater than or equal to 0.

8. Cell E according to any one of claims 1 to 7<1>Wherein the connecting piece V _AM <15>Formed in electrolytic cell E<1>And (3) inner part.

9. Solution L for producing an alkali metal alkoxide XOR in an alcohol ROH ₁ <21>Wherein X is an alkali metal cation and R is an alkyl group having 1 to 4 carbon atoms,

wherein the following steps (β1), (β2), (β3) carried out simultaneously are carried out in an electrolytic cell E <1> according to any of claims 1 to 8:

(beta 1) solution L comprising alcohol ROH ₂ <22>Transport through K _K <12>，

(beta 2) neutral or alkaline aqueous solution L of salt S containing X as cation ₃ <23>Transport through K _M <13>Then via V _AM <15>Then pass through K _A <11>，

(beta 3) at E _A <113>And E is _K <123>A voltage is applied between the two electrodes,

this is at the outlet A _KK <121>Where the solution L is provided ₁ <21>Wherein L is ₁ <21>The XOR concentration in (a) is higher than L ₂ <22>The concentration of the XOR in (a),

and this is at the outlet a _KA <111>Aqueous solution L where S is provided ₄ <24>Wherein L is ₄ <24>In S concentration lower than L ₃ <23>S concentration in (b).

10. The method of claim 9, wherein X is selected from Li ⁺ 、Na ⁺ 、K ⁺ 。

11. A method according to claim 9 or 10, wherein S is a halide, sulfate, sulfite, nitrate, bicarbonate or carbonate of X.

12. The method according to any one of claims 9 to 11, wherein R is selected from methyl and ethyl.