IMPROVED METHOD FOR THE DEPOLYMERIZATION OF POLYETHYLENE ENTEREPHTHALATE

Description

[0001] The present invention relates to a process for the depolymerization of polyethylene terephthalate (= "PET" ), in which PET with electrolytically produced alkali metal glycolate, in particular sodium or potassium glycolate, to a mixture M 1 comprehensive bis-2-hydroxyethyl terephthalate (= " HEALTHY "; CAS No.: 959-26-2) is implemented.

[0002] The method according to the invention is characterized by the fact that HEALTHY a particularly high proportion among the fission products in the mixture M 1 forms. As a result, the inventive method yields a high yield of HEALTH, which is directly for the renewed PET -can be used in manufacturing.

[0003] The present invention therefore also relates to a method for recycling PET, in which the process for depolymerization of PET received HEALTH, possibly after further cleaningM 1 , again PET is polymerized. Hintergrund der Erfindung

[0004] Polyethylene terephthalate (= "PET") Polyethylene is one of the most important plastics, used in textile fibers, films, and as a material for plastic bottles. In 2007 alone, the amount used in plastic bottles was 10⁷ t (W. Caseri, Polyethylene Terephthalate, RD-16-03258 (2009) in F. Böckler, B. Dill, G. Eisenbrand, F. Faupel, B. Fugmann, T. Gamse, R. Matissek, G. Pohnert, A. Rühling, S. Schmidt, G. Sprenger, RÖMPP [Online], Stuttgart, Georg Thieme Verlag, January 2022).

[0005] Due to its durability and the on PET The sheer volume of waste generated represents one of the greatest environmental challenges of our time. The solution to this problem lies in waste prevention and efficient recycling. PET.

[0006] The prior art describes several methods for splitting PETproposed.

[0007] GB 784,248 A describes the methanolysis of PET.

[0008] Hydrolytic processes for the depolymerization of PET JP 2000-309663 A, US 4,355,175 A and T. Yoshioka, N. Okayama, A. Okuwaki, Ind. Eng. Chem. Res. 1998, 37, 336 - 340.

[0009] The implementation of PET with glycol is described in EP 0723951 A1, US 3,222,299 A, the

[0010] WO 2020 / 002999 A2, by SR Shukla, AM Harad, Journal of Applied Polymer Science 2005, 97, 513-517 (hereinafter "Shukla & Harad") and by ND Pingale, SR Shukla, European Polymer Journal 2008, 44, 4151-4156. EP1457479A1 discloses a process for the synthesis and isolation of BHET from PET with NaOH in 1,2-ethylene glycol. EP1457479A1 does not disclose the use of an electrolysis cell for the production of a glycolyte.

[0011] Shukla & Harad describe that during PET glycolysis, bis-2-hydroxyethyl terephthalate (= "HEALTHY") This fission product can simultaneously serve as a starting material for the production of new materials. PETs be used.

[0012] Therefore, there is an interest in methods for the depolymerization of PET, where the highest possible proportion of HEALTHY is obtained among the fission products.

[0013] The object of the present invention was to provide such a method. Kurzbeschreiung der Erfindung

[0014] A method has now been surprisingly found that solves the problem according to the invention.

[0015] The present invention relates to a process for the depolymerization of polyethylene terephthalate PET, comprehensive the following steps: (a) Preparation of a solution L 1 <21> of MA glycolate in glycol, wherein MA is an alkali metal cation, in particular selected from lithium, potassium, sodium, preferably selected from potassium, sodium, and most preferably sodium, in an electrolysis cell E <1> , comprising at least one anode chamber AN <11> with at least one inlet Z KA <110> , at least one process A KA <111> and an interior I KA <112> , which is an anodic electrode EA <113> includes at least one cathode chamber KK <12> with at least one inlet Z KK <120> , at least one process A KK <121> and an interior In KK <122> , which is a cathodic electrode EK <123> includes, and optionally at least one intermediate middle chamber KM <13> with at least one inlet Z KM <130> , at least one process A KM <131> and an interior In KM <132> , whereby then IN THE <112> and In KM <132> through a diffusion barrier D <14> are separated from each other, and A KM <131> through a connection V AM <15> with the inflow Z KA <110> is connected, so that through the connection V AM <15> liquid from In KM <132> in IN THE <112> can be directed, whereby in cases where the electrolysis cell E <1> no middle chamber KM <13> includes IN THE <112> and In KK <122> through a partition wall W <16> are separated from each other in cases where the electrolysis cell E <1> at least one middle chamber KM <13> includes In KK <122> and In KM <132> through a partition wall W <16> are separated from each other, with the partition wall W <16> one page S KK <161> with the surface O KK <163> and one of the pages S KK <161> opposite side SA / MK<162> with the surface OA / MK <164> features the partition W <16> at least one alkali-cation-conducting solid electrolyte ceramic FA <18> encompassed in such a way that the partition wall W <16> comprised alkali-cation-conducting solid electrolyte ceramic FA <18> the interior In KK <122> on the page S KK <161> over the surface O KK <163> directly contacted, and in cases where the electrolysis cell E <1> no middle chamber KM <13> includes those separated by the partition wall W <16> comprised alkali-cation-conducting solid electrolyte ceramic FA <18> the interior IN THE <112> on the page SA / MK <162> over the surface OA / MK <164> directly contacted, in cases where the electrolysis cell E <1> at least one middle chamber KM <13> includes those separated by the partition wall W<16> comprised alkali-cation-conducting solid electrolyte ceramic FA <18> the interior In KM <132> on the page SA / MK <162> over the surface OA / MK <164> directly contacted, (α) wherein in the electrolysis cell E <1> , if these do not have a middle chamber KM <13> The following steps (α1), (α2), (α3) are performed simultaneously: (α1) a solution L 2 <22> comprehensive glycol is by In KK <122> directed, (α2) a neutral or alkaline aqueous solution L 3 <23> a salt S comprehensive MA as a cation is by IN THE <112> guided, (α3) between EA <113> and EK <123> voltage is applied, or (β) wherein in the electrolysis cell E <1> , if these have at least one middle chamber KM <13> The following steps (β1), (β2), (β3) are performed simultaneously: (β1) a solution L 2 <22> comprehensive glycol is by In KK <122> directed, (β2) a neutral or alkaline aqueous solution L 3 <23> a salt S comprehensive MA as a cation is by In KM <132> , then about V AM <15> , then through IN THE <112> guided, (β3) between EA <113> and EK <123> Voltage is applied, which alters the process A KK <121> the solution L 1 <21> is obtained, whereby the concentration of MA glycolate in L 1 <21> is higher than in L 2 <22> , and which affects the process A KA <111> an aqueous solution L 4 <24> from S is obtained, whereby the concentration of S in L 4 <24> is lower than in L 3 <23> ; (b) Implementation of the solution L 1 <21> with PET to a mixture M 1 comprising bis-2-hydroxyethyl terephthalate (= "HEALTH").

[0016] In another aspect, the present invention relates to a method for recycling PET, in which in one step (ζ) the depolymerization obtained in the inventive process HEALTHY to PET is polymerized.

[0017] It was surprisingly found that during the implementation of the PETs with the solution obtained by the electrolytic process according to the invention L 1 <21> a higher proportion of HEALTHY is obtained as in conventional methods, in which the alkaline alkali metal glycolate solution is obtained by mixing the glycol in the corresponding alkali metal hydroxide. Abstract Abbildungen 1 A and 1 B

[0018] Table 1 A (= " Figs. 1 A") shows the inventive process for producing the sodium glycol solution L 1 <21> in an electrolysis cell E <1> This includes a cathode chamber. KK <12> and an anode chamber AN <11> .

[0019] The cathode chamber KK <12> includes a cathodic electrode EK <123> inside I KK <122> , an inflow Z KK <120> and a process A KK <121> .

[0020] The anode chamber AN <11> includes an anodic electrode EA <113> inside IN THE <112> , an inflow Z KA <110> and a process A KA <111> .

[0021] The two chambers AN <11> and KK <12> are from an exterior wall OR <80> the two-chamber cell E <1> limited. The interior In KK <122> is also separated by a partition wall W <16> , which consist of a disc of a NaSICON solid electrolyte ceramic selectively permeable to sodium ions FA <18> consists of the interior IN THE <112> separated. The NaSICON solid electrolyte ceramic FA<18> extends over the entire depth and height of the two-chamber cell E <1> The partition wall has two sides. S KK <161> and SA / MK <162> on, whose surfaces O KK <163> and OA / MK <164> the respective interior In KK <122> or IN THE <112> contact.

[0022] An aqueous solution of sodium chloride L 3 <23> at pH 10.5, it is added via the inlet Z KA <110> against gravity into the interior IN THE <112> given.

[0023] Via the inlet Z KK <120> A solution of 1 wt% sodium glycolate in glycol is prepared. L 2 <22> into the interior In KK <122> guided.

[0024] A voltage is applied between the cathodic electrode. EK <123> and the anodic electrode EA <113> This creates an interior space. In KK <122> Glycol in the electrolyte L 2 <22> Reduced to glycolate and H₂ (H₂CH₂OH + e⁻ → H₂CH₂O⁻ + ½ H₂; also H₂CH₂O⁻ + e⁻ → -< H₂CH₂O⁻ + ½ H₂). Sodium ions diffuse outwards from the interior. IN THE <112> through the NaSICON solid electrolyte ceramic FA <18> into the interior In KK <122> This increases the overall concentration of sodium glycolate in the indoor air. In KK <122> , which alters the process A KK <121> a glycolic solution of sodium glycolate L 1 <21> is obtained, whose concentration of sodium glycolate compared L 2 <22> is increased and is at ~20 wt% sodium glycolate in glycol.

[0025] Inside IN THE <112> The oxidation of chloride ions to molecular chlorine takes place (Cl⁻ → ½ Cl₂ + e⁻). During the process... A KA <111> an aqueous solution L 4 <24> obtained, in which the content of NaCl is compared to L 3 <23> The effect is reduced. Chlorine gas (Cl₂) reacts with water to form hypochlorous acid and hydrochloric acid according to the reaction Cl₂ + H₂O → HOCl + HCl, which react with further water molecules to produce acids. This acidity damages the NaSICON solid electrolytic ceramic. FA <18> .

[0026] Figure 1 B (= " Figs. 1 B ") shows a further embodiment of the method according to the invention using an electrolysis cell E <1> , which is a middle chamber KM <13> This three-chamber cell includes E <1> It therefore includes a cathode chamber KK <12> , an anode chamber AN <11> and an intermediate middle chamber KM <13> .

[0027] The cathode chamber KK <12> includes a cathodic electrode EK <123> inside In KK <122> , an inflow Z KK <120> and a process A KK <121> .

[0028] The anode chamber AN <11> includes an anodic electrode EA <113> inside IN THE <112> , an inflow Z KA <110> and a process A KA <111> .

[0029] The middle chamber KM <13> includes an interior In KM <132> , an inflow Z KM <130> and a process A KM <131> .

[0030] The interior IN THE <112> is with the interior In KM <132> via the connection V AM <15> tied together.

[0031] The three chambers are separated by an outer wall. OR <80> the three-chamber cell E <1> limited. The interior In KM <132> the middle chamber KM <13> is also separated by a partition wall W <16> , which consist of a disc of a NaSICON solid electrolyte ceramic selectively permeable to sodium ions FA <18> consists of the interior In KK <122> the cathode chamber KK <12> separated. The NaSICON solid electrolyte ceramic FA<18> extends over the entire depth and height of the three-chamber cell E <1> The partition wall has two sides. S KK <161> and SA / MK <162> on, whose surfaces O KK <163> and OA / MK <164> the respective interior In KK <122> or In KM <132> contact.

[0032] The interior In KM <132> the middle chamber KM <13> is additionally protected by a diffusion barrier D <14> from the interior IN THE <112> the anode chamber AN <11> separated. The NaSICON solid electrolyte ceramic FA <18> and the diffusion barrier D <14> extend over the entire depth and height of the three-chamber cell E <1> The diffusion barrier D <14> is a cation exchange membrane (sulfonated PTFE).

[0033] In the embodiment according to Figure 1 B will the connection V AM <15> outside the electrolysis cellE <1> formed, in particular by a pipe or hose, the material of which may be selected as rubber, metal or plastic. By the connection V AM <15> Can liquid from the interior In KM <132> the middle chamber KM <13> into the interior IN THE <112> the anode chamber AN <11> outside the outer wall OR <80> the three-chamber cell E <1> be routed. The connection V AM <15> connects the process A KM <131 >, which is at the bottom of the middle chamber KM <13> the outer wall OR <80> the electrolysis cell E <1> breaks through, with the inflow Z KA <110> , which is located at the bottom of the anode chamber AN <11> the outer wall OR <80> the electrolysis cell E <1> breaks through.

[0034] An aqueous solution of sodium chloride L 3 <23> at pH 10.5, it is added via the inlet Z KM<130> aligned with gravity into the interior In KM <132> the middle chamber KM <13> given. Through the connection V AM <15> is the interior In KM <132> the middle chamber KM <13> with the interior IN THE <112> the anode chamber AN <11> connected. Sodium chloride solution L 3 <23> is through this connection V AM <15> from the interior In KM <132> into the interior In KM <112> guided.

[0035] Via the inlet Z KK <120> A solution of ~1 wt% sodium glycolate in glycol is prepared. L 2 <22> into the interior In KK <122> guided.

[0036] A voltage is applied between the cathodic electrode. EK <123> and the anodic electrode EA <113> This creates an interior space. In KK <122> Glycol in the electrolyte L 2 <22> Reduced to glycolate and H₂ (H₂CH₂OH + e⁻ → H₂CH₂O⁻ + ½ H₂; also H₂CH₂O⁻ + e⁻ → -< H₂CH₂O⁻ + ½ H₂). Sodium ions diffuse outwards from the interior. In KM <132> the middle chamber KM <103> through the NaSICON solid electrolyte ceramic FA <18> into the interior In KK <122> This increases the overall concentration of sodium glycolate in the indoor air. In KK <122> , which alters the process A KK <121> a glycolic solution of sodium glycolate L 1 <21> is obtained, whose concentration of sodium glycolate compared L 2 <22> The sodium glycolate content in glycol is increased to approximately 20 wt%.

[0037] Inside IN THE <112> The oxidation of chloride ions to molecular chlorine takes place (Cl⁻ → ½ Cl₂ + e⁻). During the process... A KA <111> an aqueous solution L 4 <24> obtained, in which the content of NaCl is compared to L 3 <23> is reduced. Chlorine gas (Cl₂) reacts with water to form hypochlorous acid and hydrochloric acid according to the reaction Cl₂ + H₂O → HOCl + HCl, which react with further water molecules to produce acids. The acidity would affect the NaSICON solid electrolyte ceramic. FA <18> damage, but is prevented by the arrangement in the three-chamber cell on the anode chamber AN <11> limited and therefore in the electrolysis cell E <1> from the NaSICON solid electrolyte ceramic FA <18> They are kept away. This significantly increases their lifespan. Abbildungen 2 A and 2 B

[0038] Table 2 A (= " Figs. 2 A") shows a preferred partition W <16> This includes two NaSICON solid electrolyte ceramics. FA <18> and FB <19> , separated by a separating element T <17> are separated from each other and are each attached without gaps. The separating element T<17> It has the geometric shape of a cuboid, on whose opposite sides FA <18> and FB <19> are attached without gaps (e.g. by adhesive).

[0039] The page S KK <161> with the surface O KK <163> lies in the image plane, the side SA / MK <162> with the not in Fig. 2 A visible surface OA / MK <164> behind the image plane.

[0040] Figure 2B (= Fig. 2 B) shows another embodiment of a preferred partition wall W <16> This includes four NaSICON solid electrolyte ceramics. FA <18> , FB <19> , FC <28> , FD <29> , separated by a separating element T <17> are separated from each other and are each attached without gaps. The separating element T <17> It has the shape of a cross, on whose opposite sides FA <18> , FB <19> , FC <28> and FD<29> are stuck fast. The page S KK <161> with the surface O KK <163> lies in the image plane, the side SA / MK <162> with the not in Fig. 2 B visible surface OA / MK <164> behind the image plane. Figures 3A to 3C

[0041] Figure 3A (= " Fig. 3 Figure A) shows the detailed view, which is highlighted by a dashed circle in Figures 2A and 2B. As described, the respective solid electrolyte ceramics are FA <18> and FB <19> at the separating element T <17> for example, attached with adhesive.

[0042] Figure 3B (= " Fig. 3 B") illustrates a further embodiment of a preferred partition W. Here the separating element indicates T <17> two concave depressions (grooves) into which the two solid electrolyte ceramics FA <18> and FB<19> can be fitted. The shape of the edges of the solid electrolyte ceramics can be used for this purpose. FA <18> and FB <19> They will be mechanically adapted accordingly. Additionally, a seal will be installed. Di <40> used, for example with an adhesive on the separating element T <17> and the respective solid electrolyte ceramic FA <18> or FB <19> is attached. The separating element T <17> It can consist of two or more parts. <171> and <172> consist of those, as indicated by the dotted line in Fig. 3 B indicated, they can be attached to one another. With appropriate geometry and adaptation of the shape of the edges of the solid electrolyte ceramics. FA <18> or FB <19> can the latter be placed between the two parts <171> and <172> clamped, which increases the stability of the connection separating element T <17> / Ceramics FA <18> or FB <19> and the tightness of the partition wall W<16> further improved.

[0043] Figure 3C (= " Fig. 3 C") illustrates a further embodiment of a preferred partition W. This corresponds to the one in Figure 3B described, except that the depressions (grooves) in the separating element T <17> , into which the two solid electrolyte ceramics FA <18> and FB <19> They should be fitted, not concave, but tapered to a point. Figures 4A to 4D

[0044] Figures 4 A (= " Fig. 4 A") to 4D show further embodiments of preferred partitions W <16> .

[0045] The in Figure 4A shown partition wall W <16> corresponds to the in Figure 2A shown partition wall W <16> , except that it also forms a frame element R <20> This includes all surfaces of the partition wall. W <16> except O KK <163> and OA / MK<164> complete. The frame element R <20> is not integral with the separating element T <17> executed.

[0046] Figure 4B (= " Fig. 4 B") shows another embodiment of a preferred partition W <16> This corresponds to the one in Figure 4A in the illustrated embodiment, except that it has two frame elements R <20> includes the upper and lower surfaces of the partition. W <16> limit.

[0047] Figure 4 C (= " Fig. 4 C") shows another embodiment of a preferred partition W <16> The in Figure 4 C shown partition wall W <16> corresponds to the in Figure 2 B shown partition wall W <16> , except that it also forms a frame element R <20> This includes all surfaces of the partition wall. W <16> except O KK <163> and OA / MK <164> complete. The frame element R<20> is not integral with the separating element T <17> executed.

[0048] Figure 4D (= " Fig. 4 D ") shows a further embodiment of a preferred partition W <16> This corresponds to the one in Figure 4 C in the illustrated embodiment, except that it has two frame elements R <20> includes the upper and lower surfaces of the partition. W <16> limit. Figures 5A and 5B

[0049] Figure 5A (= " Fig. 5 A") shows an electrolysis cell E <1> in a preferred embodiment of the method according to the invention. This corresponds to the one in Figure 1 A depicted electrolysis cell with the difference that a partition W <16> the interior I KK <122> the cathode chamber KK <12> from the interior I KA <112> the anode chamber KA <11 > separates. The partition is the one shown in Figures 2A and 2B.

[0050] Figure 5B (= " Fig. 5 B") shows an electrolysis cell E <1> in a preferred embodiment of the method according to the invention. This corresponds to the one in Figure 1 A depicted electrolysis cell with the difference that a partition W <16> the interior I KK <122> the cathode chamber KK <12> from the interior I KA <112> the anode chamber KA <11 > separates. The partition wall W <16> is the one shown in Figures 4A to 4D. The frame element R <20> forms part of the outer wall WA <80> , so that the partition W <16> included solid electrolyte ceramics before the pressure exerted by the partition W <16> would affect them if they were part of the partition W<16> would be protected. In addition, the solid electrolyte ceramics are thus completely used for the separation of the interior spaces I KK. <122> and I KA <112> within the electrolysis cell E <1> They are used because they are not partially obscured by the outer wall. Figures 6A and 6B

[0051] The Figure 6A (= Fig. 6 A) The inventive method is shown using an electrolysis cell. E <1> , which is in the Fig. 1 B shown, with the difference being that the connection V AM <15> from the interior I KM <132> the middle chamber KM <13> to the interior I KA <112> the anode chamber KA <11> through multiple perforations in the diffusion barrier D <14> is formed. These perforations can subsequently occur in the diffusion barrier. D <14> are stamped or already due to the manufacturing process of the diffusion barrier D<14> These perforations are present from the outset (e.g., in textile fabrics such as filter cloths or metal fabrics). In this embodiment, the entirety of these perforations constitutes the connection. V AM <15> through which electrolyte from the interior I KM <132> into the interior I KA <112> can be directed.

[0052] Figure 6B (= " Fig. 6 B") shows a further embodiment of the method according to the invention using an electrolysis cell E <1> This corresponds to the one in Figure 1 B shown electrolysis cell E <1> with the difference that the connection V AM <15> from the interior I KM <132> the middle chamber KM <13> to the interior I KA <112> the anode chamber KA <11> is formed by a gap that exists between the diffusion barrier D <14> and the outer wall WA<80> forms a gap. This gap can be created by removing an otherwise dense diffusion barrier. D <14> so in the electrolysis cell E <1> is arranged so that they occupy the interior I KM <132> the middle chamber KM <13> not completely from the interior I KA <112> the anode chamber KA <11> separates, but a gap serves as a connection V AM <15> will be maintained. Figures 7A and 7B

[0053] Figure 7A (= " Fig. 7 A") shows another embodiment of a preferred partition W <16> This includes four NaSICON solid electrolyte ceramics. FA <18> , FB <19> , FC <28> and FD <29> , separated by a separating element T <17> , which has two halves <171> and <172> The partition wall W <16> also includes a frame element R<20> , which also consists of two halves <201> and <202> consists.

[0054] The partition wall W <16> consists of two foldable parts, in which half <171> of the separating element T <17> with half <201> of the frame element R <20> is in one piece and half <172> of the separating element T <17> with half <202> of the frame element R <20> It is a single piece. These two parts can optionally be connected by a hinge. <50> connected to each other and, when folded, secured via the lock <60> to be locked in place. The four NaSICON solid electrolyte ceramics are positioned between these halves. FA <18> , FB <19> , FC <28> and FD <29> clamped, with a seal acting as a gasket in each case for sealing Di <40> A functioning ring is used.

[0055] The left side of the Figure 7A The frontal view shows the side view S KK<161> with the surface O KK <163> the partition wall W <16> . The one that acts as a seal Di <40> Functional rings are indicated with dashed outlines. The right side of the illustration shows the side view of the partition. W <16> .

[0056] Figure 7B (= " Fig. 7 B") shows another embodiment of a preferred partition W <16> This corresponds to the one in Figure 7A described embodiment, except that it uses nine NaSICON solid electrolyte ceramics FA <18> , FB <19> , FC <28> , FD <29> , FE <30> , FF <31> , FG <32> , FH <33> , FI <34> includes. Figure 8

[0057] The Figure 8 (= Fig. 8 ) shows the comparison of the levels of BHET ("1"), 2-hydroxyethyl terephthalate (MHET); "2") and terephthalate (" TS";"3") during depolymerization with sodium glycolate obtained according to the inventive process as well as with sodium glycolate obtained by conventional processes.

[0058] The bars with the close hatching " / / / / / / / " show the respective content of BHET, MHET and TS in the reactor discharge during the depolymerization of PET according to the inventive example E1, in which the sodium glycolate used for depolymerization was obtained by electrolysis.

[0059] The black bars show the respective salary of BHET, MHET and TS in the reactor discharge during the depolymerization of PET according to the comparative example V1, in which only glycol was used during depolymerization.

[0060] The bars with the bold hatching " / / / / / " indicate the respective content of BHET, MHET and TS in the reactor discharge during the depolymerization of PETaccording to the comparative example V2, in which the sodium glycolate used for depolymerization was obtained by mixing NaOH and glycol in the reactor. Detailed description of the invention

[0061] It has now been surprisingly discovered that the glycolysis of PET The process is particularly efficient when alkali metal glycolate, especially sodium or potassium glycolate, obtained electrolytically, is used. It has been observed that, in the process according to the invention, compared to prior art processes using glycolate obtained by dissolving the corresponding alkali metal hydroxides in glycol, a higher proportion of BHET is obtained in the fission product. Step 1 (a): Electrolysis to obtain solution L1 comprising glycol and MA glycolate

[0062] The solution used in the method according to the invention L 1 According to the invention, a glycol and MA glycolate is electrolytically treated in an electrolysis cell. E <1> receive.

[0063] For the purposes of this invention, "glycol" means 1,2-ethylenediol with the chemical formula HO-CH 2 -CH 2 -OH (CAS No. 107-21-1).

[0064] For the purposes of the invention, "MA-glycolate" means the salt of glycol containing MA. The term "MA-glycolate" includes at least one of MA O-CH₂-CH₂-OH and MA O-CH₂-CH₂-OM A, preferably at least MA O-CH₂-CH₂-OH, most preferably MA O-CH₂-CH₂-OH and MA O-CH₂-CH₂-OM A.

[0065] MA is an alkali metal cation, which is selected in particular from lithium, sodium, and potassium, and preferably from sodium and potassium. The alkali metal cation sodium is most preferred. 1.1 Electrolysis cell E

[0066] The solution used in step (b) of the method according to the invention L 1 <21> of MA glycolate in glycol is in step (a) of the process according to the invention in an electrolysis cell E manufactured.

[0067] The electrolysis cell E includes at least one anode chamber KA and at least one cathode chamber KK and, if necessary, at least one intermediate middle chamber KM . This also includes electrolysis cells. E, which has more than one anode chamber KA and / or cathode chamber KK and / or middle chamber KM exhibiting such electrolysis cells, in which these chambers are modularly joined together, are described, for example, in DD 258 143 A3 and US 2006 / 0226022 A1.

[0068] The electrolysis cell E In a preferred embodiment of the invention, the invention comprises an anode chamber. KA and a cathode chamber KK and possibly an intermediate middle chamber KM .

[0069] The electrolysis cell E typically has an exterior wall WA up. The outer wall WAis in particular made of a material which is from the group consisting of steel, preferably rubberized steel, plastic, which is in particular selected from Telene ®< (thermoset polydicyclopentadiene), PVC (polyvinyl chloride), PVC-C (post-chlorinated polyvinyl chloride), PVDF (polyvinylidene fluoride). WA This can be particularly problematic for inlets and outlets. Within WA Then at least one anode chamber is located KA , which includes at least one cathode chamber KK and in embodiments in which the electrolysis cell E one that includes at least one intermediate middle chamber KM . 1.1.1 Cathode chamber KK

[0070] The at least one cathode chamber KK has at least one inlet Z KK , at least one process A KK and an interior I KK , one cathodic electrode EK includes, on.

[0071] The interior I KA the anode chamber KA is through a partition wall W, from the interior I KK the cathode chamber KK disconnected if the electrolysis cell E no middle chamber KM includes the interior of the cathode chamber I KK. KK is through a partition wall W, from the interior I KM the middle chamber KM disconnected if the electrolysis cell E at least one middle chamber KM includes.

[0072] The partition wall W and their arrangement in the electrolysis cell E This is described further below (section 1.1.4). 1.1.1.1 Cathodic electrode EK

[0073] The cathode chamber KK includes an interior I KK , which in turn is a cathodic electrode EK includes. As such, a cathodic electrode EKAny electrode known to a person skilled in the art that is stable under the conditions of step (a) of the method according to the invention is suitable. Such electrodes are described in particular in WO 2014 / 008410 A1, paragraph

[025] or DE 10360758 A1, paragraph

[030] . This electrode EK It can be selected from the group consisting of knitted wool, three-dimensional matrix structures, or "spheres." The cathodic electrode EK comprises in particular a material selected from the group consisting of steel, nickel, copper, platinum, platinized metals, palladium, carbon-supported palladium, titanium, preferably selected from the group consisting of steel, nickel. Preferably comprises EK Steel, preferably stainless steel (VA steel).

[0074] In the embodiments of the electrolysis cell E, in which these are a middle chamber KM It is located between the anode chamber. KAand the cathode chamber KK . 1.1.1.2 Inflow Z KK and process A KK

[0075] The cathode chamber KK also includes at least one inlet Z KK and at least one process A KK . This allows the interior I KK the cathode chamber KK liquid, such as the solution L 2 , to add and the liquid contained therein, such as the solution L 1 , to remove the inlet Z KK and the process A KK are located at the cathode chamber KK It is appropriate that the liquid flows through the interior. I KK the cathode chamber KK the cathodic electrode EK contacted. This is a prerequisite for the execution of step (a) of the inventive method to proceed as follows: A KK the solution L 1 is obtained when the solution L 2 of glycol, which optionally also includes an MA glycolate, through the interior I KK the cathode chamber KK is being managed.

[0076] The inflow Z KK and the process A KK can be carried out on the electrolysis cell according to methods known to those skilled in the art. E They can be installed, for example, by drilling holes in the outer wall and using appropriate connections (valves) that simplify the inflow and outflow of liquid. 1.1.2 Anode chamber KA

[0077] The at least one anode chamber KA has at least one inlet Z KA , at least one process A KA and an interior I KA , one anodic electrode EA includes, on.

[0078] The interior I KA the anode chamber KA is, if the electrolysis cell E a middle chamber KM includes, through a diffusion barrier D from the interior I KM the middle chamber KM separated.

[0079] If the electrolysis cell E no middle chamber KM The interior includes I KA the anode chamber K through the partition wall W from the interior I KK the cathode chamber KK separated. 1.1.2.1 Anodic electrode EA

[0080] The anode chamber KA includes an interior I KA , which in turn is an anodic electrode EA includes such an anodic electrode. EA Any electrode known to a person skilled in the art that is stable under the conditions of step (a) of the method according to the invention is suitable. Such electrodes are described in particular in WO 2014 / 008410 A1, paragraph

[024] or DE 10360758 A1, paragraph

[031] . This electrode EA It can consist of a single layer or of several flat, parallel layers, each of which may be perforated or expanded. The anodic electrode EA The anode electrode preferably comprises a material selected from the group consisting of ruthenium oxide, iridium oxide, nickel, cobalt, nickel tungstate, nickel titanate, and precious metals such as platinum, which is supported on a substrate such as titanium or Kovar® (an iron / nickel / cobalt alloy in which the individual proportions are preferably as follows: 54 wt% iron, 29 wt% nickel, 17 wt% cobalt). Other possible anode materials are, in particular, stainless steel, lead, graphite, tungsten carbide, and titanium diboride. EA a titanium anode coated with ruthenium oxide / iridium oxide (RuO 2 + IrO 2 / Ti). 1.1.2.2 Inflow Z KA and process A KA

[0081] The anode chamber KA also includes an inlet Z KA and a process A KA . This allows the interior I KA the anode chamber KA liquid, such as the solutionL 3 , to add and the liquid contained therein, such as the solution L 4 , to remove the inlet Z KA and the process A KA are located at the anode chamber KA It is appropriate that the liquid flows through the interior. I KA the anode chamber KA the anodic electrode EA contacted. This is a prerequisite for the execution of step (a) of the inventive method to proceed as follows. A KA the solution L 4 is obtained when the solution L 3 a salt S through the interior I KA the anode chamber KA is being managed.

[0082] The inflow Z KA and the process A KA can be carried out on the electrolysis cell according to methods known to those skilled in the art. EThey can be installed, for example, by drilling holes in the outer wall and installing corresponding connections (valves) that simplify the inflow and outflow of liquid. The inlet Z KA In certain embodiments, in which the electrolysis cell E has a central chamber KM includes, for example, within the electrolysis cell, such as perforations in the diffusion barrier. D. 1.1.3 Optional middle chamber KM

[0083] The electrolysis cell used in step (a) of the inventive method E may have at least one middle chamber KM on. The optional center chamber KM lies between the cathode chamber KK and anode chamber KA . It includes at least one inlet Z KM , at least one process A KM and an interior I KM .

[0084] The interior I KA the anode chamber KA is, if the electrolysis cell Ea middle chamber KM includes, through a diffusion barrier D from the interior I KM the middle chamber KM separated. A KM is then also through a connection V AM with the inflow Z KA connected, so that through the connection V AM liquid from I KM in I KA can be directed. 1.1.3.1 Diffusion barrier D

[0085] The interior I KM the optional center chamber KM is separated by a diffusion barrier D from the interior I KA the anode chamber KA separated and through the partition wall W from the interior I KK the cathode chamber KK separated.

[0086] For the diffusion barrier D Any material can be used which is stable under the conditions of step (a) of the inventive method and which facilitates the transfer of protons from the interior I KAthe anode chamber KA liquid inside the interior I KM the optional center chamber KM prevents or slows down.

[0087] As a diffusion barrier D In particular, a non-ion-specific partition or a membrane permeable to specific ions is used. Preferably, the diffusion barrier is... D to form a non-ion-specific partition.

[0088] The material of the non-ion-specific partition is selected in particular from the group consisting of fabrics, in particular textile or metal fabrics, glass, in particular sintered glass or glass frits, ceramics, in particular ceramic frits, and membrane diaphragms, and is particularly preferably a textile or metal fabric, and more preferably a textile fabric. The textile fabric preferably comprises plastic, more preferably a plastic selected from PVC, PVC-C, polyvinyl ether ("PVE"), or polytetrafluoroethylene ("PTFE").

[0089] Is the diffusion barrier DAccording to the invention, a "membrane permeable to specific ions" means that the respective membrane promotes the diffusion of certain ions through it compared to other ions. In particular, this refers to membranes that promote the diffusion through them of ions of a specific charge compared to oppositely charged ions. Even more preferably, membranes permeable to specific ions also promote the diffusion through them of certain ions with one charge compared to other ions of the same charge.

[0090] Is the diffusion barrier D A "membrane permeable to specific ions" is, in particular, the diffusion barrier. D around an anion-conducting membrane or around a cation-conducting membrane.

[0091] Anion-conducting membranes according to the invention are those that selectively conduct anions, preferably specific anions. In other words, they favor the diffusion of anions through them compared to that of cations, particularly protons; even more preferably, they additionally favor the diffusion of specific anions through them compared to the diffusion of other anions through them.

[0092] According to the invention, cation-conducting membranes are those that selectively conduct cations, preferably specific cations. In other words, they favor the diffusion of cations through them compared to that of anions; even more preferably, they additionally favor the diffusion of specific cations through them compared to the diffusion of other cations through them; and even more preferably, the diffusion of cations other than protons, and even more preferably sodium cations, compared to protons.

[0093] "Promoting the diffusion of certain ions X over the diffusion of other ions Y" means in particular that the diffusion coefficient (unit m 2< / s) of ion type X at a given temperature for the membrane in question is higher by a factor of 10, preferably 100, preferably 1000 than the diffusion coefficient of ion type Y for the membrane in question.

[0094] Is the diffusion barrier D To create a "membrane permeable to specific ions", an anion-conducting membrane is preferred, as this is particularly good at preventing the diffusion of protons from the anode chamber. KA into the middle chamber KM .

[0095] In particular, an anion-conducting membrane such as one suitable for the salt S The anions included are selective. Such membranes are known to those skilled in the art and can be used by them. According to the invention, the salt comprises SMA as a cation.

[0096] The salt S is preferably a halide, sulfate, sulfite, nitrate, hydrogen carbonate or carbonate of MA, more preferably a halide.

[0097] Halides are fluorides, chlorides, bromides, and iodides. The most common halide is chloride.

[0098] Preferably, a membrane selective for halides, preferably chloride, is used as the anion-conducting membrane.

[0099] Anion-conducting membranes are described, for example, by MA Hickner, AM Herring, EB Coughlin, Journal of Polymer Science, Part B: Polymer Physics 2013, 51, 1727-1735, by CG Arges, V. Ramani, PN Pintauro, Electrochemical Society Interface 2010, 19, 31-35, in WO 2007 / 048712 A2 and on page 181 of the textbook by Volkmar M. Schmidt Electrochemical Process Engineering: Fundamentals, Reaction Engineering, Process Optimization, 1st edition (October 8, 2003).

[0100] Even more preferably, organic polymers, selected in particular from polyethylene, polybenzimidazoles, polyetherketones, polystyrene, polypropylene, or fluorinated membranes such as polyperfluoroethylene, preferably polystyrene, are used as anion-conducting membranes, wherein these have covalently bonded functional groups selected from -NH3+<, -NRH2+<, -NR3+<, =NR+<; -PR3+<, where R is an alkyl group with preferably 1 to 20 carbon atoms, or other cationic groups. Preferably, they have covalently bonded functional groups selected from -NH3+<, -NRH2+<, -NR3+<, more preferably selected from -NH3+<, -NR3+<, even more preferably -NR3+<.

[0101] If the diffusion barrier D A cation-conducting membrane is, in particular, a membrane that is suitable for MA, i.e., the salt S The cation included is selective. The diffusion barrier is even more favored.D an alkali cation-conducting membrane, more preferably a potassium and / or sodium ion-conducting membrane, most preferably a sodium ion-conducting membrane.

[0102] Cation-conducting membranes are described, for example, on page 181 of the textbook by Volkmar M. Schmidt Electrochemical Process Engineering: Fundamentals, Reaction Engineering, Process Optimization, 1st edition (October 8, 2003).

[0103] Even more preferably, organic polymers are used as cation-conducting membranes, which are selected in particular from polyethylene, polybenzimidazoles, polyetherketones, polystyrene, polypropylene or fluorinated membranes such as polyperfluoroethylene, preferably polystyrene, polyperfluoroethylene, wherein these carry covalently bonded functional groups selected from -SO 3 -< , -COO -< , -PO 3 2-< , -PO 2 H -< , preferably -SO 3 -< , (described in DE 10 2010 062 804 A1, US 4,831,146).

[0104] This could be, for example, a sulfonated polyperfluoroethylene (Nafion®< with CAS number: 31175-20-9). These are known to those skilled in the art, for example, from WO 2008 / 076327 A1, paragraph

[058] , US 2010 / 0044242 A1, paragraph

[0042] or US 2016 / 0204459 A1 and are available under the trade names Nafion®<, Aciplex®< F, Flemion®<, Neosepta®<, Ultrex®<, PC-SK®<. Neosepta®< membranes are described, for example, by S.A. Mareev, D.Yu. Butylskii, ND Pismenskaya, C Larchet, L Dammak, VV Nikonenko, Journal of Membrane Science 2018, 563, 768-776.

[0105] Is a cation-conducting membrane used as a diffusion barrier? D For example, a polymer functionalized with sulfonic acid groups, in particular of the following formula, can be used. P NAFION , where n and m are independently of each other an integer from 1 to 10⁶, preferably an integer from 10⁶ to 10⁵, and even more preferably an integer from 10⁶ to 10⁴. 1.1.3.2 Inflow Z KM and process A MK

[0106] The optional center chamber KM also includes an inlet Z KM and a process A KM . This allows the interior I KM the middle chamber KM liquid, such as the solution L 3 , to add, and any liquid contained therein, such as the solution L 3 , into the interior I KA the anode chamber KA to transfer.

[0107] The inflow Z KM and the process A KM can be carried out on the electrolysis cell according to methods known to those skilled in the art. E They can be installed, for example, by drilling holes in the outer wall and installing corresponding connections (valves) that simplify the inflow and outflow of liquid. The process A KM It can also be located within the electrolysis cell, for example as a perforation in the diffusion barrier. D. 1.1.3.3 Connection V AM

[0108] In the electrolysis cell used in step (a) of the method according to the invention E is the process A KM through a connection V AM with the inflow Z KA connected in such a way that the connection V AM liquid from I KM in I KA can be directed.

[0109] The connection V AM can within the electrolysis cell E and / or outside the electrolysis cell E It must be formed, and is preferably formed within the electrolysis cell. 1) Is the connection V AM within the electrolysis cell E It is formed preferably through at least one perforation in the diffusion barrier. D formed. This embodiment is particularly preferred when used as a diffusion barrier. DA non-ion-specific partition, in particular a metal mesh or textile fabric, is used. This acts as a diffusion barrier. D and, due to its web properties, inherently has perforations and gaps that serve as connections. V AM function. 2) The embodiment described below is particularly preferred when used as a diffusion barrier. D A membrane permeable to specific ions is used: In this embodiment, the connection V AM outside the electrolysis cell E designed, preferably by means outside the electrolysis cell E running connection of A KM and Z KA is formed, in particular by the fact that from the interior I KM the middle chamber KM a process A KM through the outer wall WA , preferably at the bottom of the middle chamber KM , where the inflow is even more preferred Z KMon the upper side of the middle chamber KM is formed, and an influx Z KA into the interior I KA the anode chamber KA through the outer wall WA , preferably at the bottom of the anode chamber KA , The process involves the formation of components, which are connected by a conduit, for example a pipe or hose, preferably made of a material selected from rubber or plastic. A KA is then even more preferentially located on the upper side of the anode chamber KA trained.

[0110] "Process A KM at the bottom of the middle chamber KM " This means that the process A KM so at the electrolysis cell E It is appropriate that the solution L 3 the middle chamber KM departs in the same direction as gravity.

[0111] "Inflow" Z KA at the bottom of the anode chamber KA " This means that the inflow Z KA so at the electrolysis cell EIt is appropriate that the solution L 3 into the anode chamber KA occurs against gravity.

[0112] "Inflow" Z KM on the upper side of the middle chamber KM " This means that the inflow Z KM so at the electrolysis cell E It is appropriate that the solution L 3 enters the middle chamber KM in the same direction as gravity.

[0113] "Process A KA on the top of the anode chamber KA " This means that the process A KA so at the electrolysis cell E It is appropriate that the solution L 4 the anode chamber KA leaves against gravity.

[0114] This embodiment is particularly advantageous and therefore preferred when the process A KM through the outer wall WA at the bottom of the middle chamber KM , and the inflow Z KA through the outer wall WA at the bottom of the anode chamber KA , is formed. This arrangement makes it particularly easy to create an anode chamber. KA formed gases with L 4 from the anode chamber KA to derive them in order to then separate them further. Fig. 1 B shows such an embodiment.

[0115] If the connection V AM outside the electrolysis cell E trained, are especially Z KM and A KM on opposite sides of the outer wall WA the middle chamber KM arranged (e.g. Z KM on the ground and A KM on the top of the electrolysis cell E or vice versa) and Z KA and A KA on opposite sides of the outer wall WA the anode chamber KA arranged (so Z KA on the ground and A KA on the top of the electrolysis cell E or vice versa), as is particularly evident in Figure 1 B This geometry mustL 3 the two chambers KM and KA flow through. Z KA and Z KM on the same side of the electrolysis cell E be trained, which then automatically also A KM and A KA on the same side of the electrolysis cell E are trained. Alternatively, they can Z KA and Z KM , as in the Picture In the embodiment shown in B, on opposite sides of the electrolysis cell E be trained, which then automatically also A KM and A KA on opposite sides of the electrolysis cell E are trained.

[0116] 3) If the connection V AM within the electrolysis cell E This can be ensured in particular by ensuring that one side ("side A") of the electrolysis cell is designed E, where it is the top or bottom of the electrolysis cell Eacts, preferably as in Figure 6 B shown is the top side, the inlet Z KM and the process A KA includes and the diffusion barrier D Starting from this side ("side A"), the electrolysis cell E extends, but not quite to the side opposite side A ("side B") of the electrolysis cell E, which then refers to the bottom or top of the electrolysis cell E is sufficient and thereby 50% or more of the height of the three-chamber cell E, preferred 60% to 99% of the height of the three-chamber cell E, even more preferred 70% to 95% of the height of the three-chamber cell E, even more preferred 80% to 90% of the height of the three-chamber cell E, even more preferred 85% of the height of the three-chamber cell E spans. Because the diffusion barrier D side B of the three-chamber cell EIf it is not touched, a gap is created between the diffusion barrier. D and the outer wall WA side B of the three-chamber cell E. The gap then forms the connection V AM This geometry must L 3 the two chambers KM and KA completely flow through.

[0117] These embodiments best ensure that the aqueous salt solution does not come into contact with the acid-sensitive solid electrolyte. L 3 flows past before it meets the anodic electrode EA comes into contact, which leads to the formation of acids.

[0118] "Bottom of the electrolysis cell E" According to the invention, the side of the electrolysis cell is E, through one solution (e.g. L 3 at A KM in Figure 1 B) aligned with gravity from the electrolysis cell E outlet or the side of the electrolysis cell E, through one solution (e.g. L 2 at Z KK in Figures 1A, 1B, 6A and 6B and L 3 at Z KA in Figures 1A and 1B) of the electrolysis cell E is supplied against gravity.

[0119] "Top of the electrolysis cell E" According to the invention, the side of the electrolysis cell is E, through one solution (e.g. L 4 at A KA and L 1 at A KK (in Figures 1A, 1B, 6A and 6B) against gravity from the electrolysis cell E outlet or the side of the electrolysis cell E, through one solution (e.g. L 3 at Z KM in Figures 1B, 6A and 6B) of the electrolysis cell E is supplied in the same direction as gravity. 1.1.3.4 Further Exhaust Form of the Middle Chamber KM

[0120] In a preferred embodiment of the electrolysis cell E The interior includes I KM also select at least one additional feature from: 1) Components designed to be immersed in the electrolyte L 3 to cause turbulence; 2) a stirring device; 3) an additional introduction of an inert gas (e.g., nitrogen or noble gas) through an additional inlet at the bottom of the central chamber and an additional outlet at the top of the central chamber. Any gases that may be produced, such as CO₂, can also be removed via this additional outlet if the salt is present. S which is a carbonate or hydrogen carbonate, from I KM can be derived.

[0121] These additional preferred embodiments 1), 2) and 3) form in the electrolyte L 3 during the flow through the I KM This creates turbulence and eddies. As a result, the formation of a pH gradient in the central chamber is further hindered, thus preventing damage to the AFK caused by an excessively low pH. This increases the lifespan of the AFK. 1.1.4 Partition wall W

[0122] The electrolysis cell used in step (a) of the inventive method E includes a partition wall W. The partition wall W comprises at least one alkali cation-conducting solid electrolyte ceramic FA In a preferred embodiment, the partition wall consists W aus an alkali cation-conducting solid electrolyte ceramic FA

[0123] The partition wall W In an alternative preferred embodiment of the present invention, the invention comprises at least two, optionally separated by a separating element. T Separated, alkali cation-conducting solid electrolyte ceramics ("alkali cation-conducting solid electrolyte ceramic" is abbreviated as "AFK" in the following) FA and FB

[0124] The partition wall W has two sides S KK and SA / MK , which are opposite each other, on, that is, the side SA / MK is the side S KK opposite (and vice versa). The two sides S KK and s A / MK They include, in particular, essentially parallel planes.

[0125] The geometry of the partition wall W is otherwise not further restricted and can in particular be applied to the cross-section of the electrolysis cell E It can be adapted to the application in which it is used. For example, it can have the geometry of a cuboid and thus a rectangular cross-section, or the geometry of a truncated cone or cylinder and therefore a circular cross-section.

[0126] Optionally, the partition wall can be W They may also have the geometry of a cuboid with rounded corners and / or bulges, which in turn may have holes. The partition W It then has protrusions ("rabbit ears") with which the partition wall W can be fixed to electrolysis cells or to frame parts of the partition wall Wcan be fixed to each other.

[0127] The page S KK the partition wall W The surface O KK up, and the page SA / MK the partition wall W The surface OA / MK on.

[0128] The feature "partition wall" means that the partition wall W It is liquid-tight. Therefore, there are no gaps through which aqueous solution, alcoholic solution, alcohol, or water could seep in from the side. S KK to the page SA / MK or vice versa. This means that in cases where the partition wall W at least two alkali-cation-conducting solid electrolyte ceramics FA and FB and, if necessary, a separating element T includes that FA and FB and the at least one separating element that may be present T connect seamlessly to one another.

[0129] The electrolysis cell Epartition wall usable according to step (a) of the method of the invention W also includes embodiments in which the partition W comprises more than two AFKs, e.g. four or nine or twelve AFKs, where the AFKs either directly border each other or are separated by a separating element T are separated from each other.

[0130] However, if the AFKs are directly adjacent to each other, this requires a precise fit of the respective adjacent AFKs to prevent the formation of a gap between them through which aqueous liquid or water or glycol or glycolic solution can leak from the side. S KK to the page s A / MK to exclude the possibility of flow. It is therefore advantageous and preferred that, if the partition wall W more than one AFK, in the partition W all from the partition wall W AFKs included at least one separating element Tare separated from each other, meaning no AFK directly, i.e., without a separating element T in between, connecting to another AFK.

[0131] The partition wall W is further characterized by the fact that the partition wall W included AFK FA both across the surface O KK as well as over the surface OA / MK can be contacted directly.

[0132] In the embodiment in which the partition wall W at least two AFKs FA , FB Including, it is preferred that all of the partition W AFKs encompassed both the surface and the surface O KK as well as over the surface OA / MK can be contacted directly.

[0133] "Directly contactable" means, with reference to the partition wall W AFKs included that at least part of the surfaces O KK and OA / MK through the surface of the partition wall WThe AFKs are formed, meaning that they are separated by the partition wall. W included AFKs on both surfaces O KK and OA / MK are directly accessible, so that they are on both surfaces O KK and OA / MK for example, they can be wetted with aqueous solution, glycolic solution, glycol or water.

[0134] For the arrangement of the AFKs in the partition wall W This means that for each of the partition walls W AFKs included a route from the surface O KK on the page S KK on the surface OA / MK on the page SA / MK there is one that leads completely through the respective AFK.

[0135] If the partition wall W at least one separating element T typically also features at least one separating element T both over at least part of the surface O KK as well as over at least part of the surface OA / MK Directly contactable.

[0136] "Directly contactable" means, with reference to the partition wall W optionally included at least one separating element T, that part of the surfaces O KK and OA / MK through the

[0137] Surface of the separating element T is formed, that is, that the separating element T on both surfaces O KK and OA / MK is directly accessible, so that the separating element T on both surfaces O KK and OA / MK for example, it can be wetted with aqueous solution, alcoholic solution, alcohol or water.

[0138] For the arrangement of the optional separating element T in the partition wall W This means in particular that it is necessary for the partition wall W Optionally included separating element T a way from the surface O KK on the page S KKto the surface OA / MK on the page SA / MK there is, which through the separating element T, and possibly by a seal The, but not through an AFK.

[0139] In a preferred embodiment of the partition wall W at least 50%, preferably at least 60%, even more preferably at least 70%, and even more preferably at least 85% of the surface area will be covered. OA / MK through the partition wall W AFKs were formed.

[0140] In a preferred embodiment of the partition wall W at least 50%, preferably at least 60%, even more preferably at least 70%, and even more preferably at least 85% of the surface area will be covered. O KK through the partition wall W AFKs were formed.

[0141] In the embodiment in which the partition wall Wmore than one AFK, in particular 50% to 99%, preferably at least 60% to 96%, even more preferably 70% to 92%, even more preferably 85% to 90% of the surface O KK through the partition wall W AFKs were formed, with the remainder of the surface being even more preferably formed. O KK through the separating element T and, if applicable, the frame element R are formed. At the same time, in the embodiment in which the partition wall W more than one AFK, in particular 50% to 99%, more preferably at least 60% to 96%, more preferably 70% to 92%, more preferably 85% to 90% of the surface OA / MK through the partition wall W AFKs were formed, with the remainder of the surface being even more preferably formed. OA / MK through the separating element T and, if applicable, the frame element R be formed.

[0142] In the preferred embodiment, the partition wall comprises W <16> an alkali-cation-conducting solid electrolyte ceramic FA and, if necessary, a frame element R. Even more preferably, the partition wall consists of W <16> made from an alkali-cation-conducting solid electrolyte ceramic FA

[0143] In another preferred embodiment, the partition wall comprises W at least four AFKs FA , FB , FC and FD , where they would then prefer exactly four AFKs FA , FB , FB and FD includes.

[0144] In a further preferred embodiment, the partition wall comprises W at least nine AFKs FA, FB, FC, FD, FE, FF, FG, FH and AND where they would then prefer exactly nine AFKs FA, FB, FC, FD, FE, FF, FG, FH and AND includes.

[0145] In a further preferred embodiment, the partition wall comprises W at least twelve AFKs FA, FB, FC, FD, FE, FF, FG, FH, FI, FJ, FK and FL , FLwhere they would then prefer exactly twelve AFKs FA, FB, FC, FD, FE, FF, FG, FH, FI, FJ, FK and FL includes.

[0146] By arranging at least two AFKs side by side in the partition wall W This offers an advantage over the arrangement of only one AFK (anti-friction ceramic) layer, namely a further direction of propagation for the AFKs in response to the temperature fluctuations that occur during the operation of the electrolysis cell. NaSICON discs, which act as partitions, are confined within electrolysis cells by the outer walls of the electrolysis cell or by solid plastic frames. The mechanical stresses occurring within the NaSICON during expansion cannot thus be dissipated, which can lead to ceramic fracture.

[0147] In contrast, the individual AFKs within the partition wall are separated. W preferably attached to the separating element T, which leads to two beneficial effects, both of which increase the long-term stability of the AFK: Each AFK has at least one additional degree of freedom available, meaning one dimension in which it can extend. Besides extension in the z-direction (i.e., across the thickness of the ceramic disk at right angles to the plane of the partition), W ) an extension in the x and / or y direction is now also possible, i.e. in the horizontal and vertical direction within the plane of the partition wall. W.This direction of expansion is not given or at least severely restricted if the AFKs, for example, span the cross-section of the electrolysis cell as a solid disk and border the solid wall of the electrolysis cell; compared to an equally sized partition wall consisting of only one AFK, the division into several small AFKs results in the voltages occurring within the smaller AFKs being absolutely smaller, being able to be dissipated more quickly, and thus not building up as quickly to a voltage that leads to the AFK breaking.

[0148] This breaks the tendency for the "divided" AFKs in the partition wall to W significantly reduced compared to using a disc. 1.1.4.1 Alkalication Enabler Feste Electrolyte Ceramics "AFK" .

[0149] As from the partition wall W included alkali-cation-conducting solid electrolyte ceramics FA , FBetc. Any solid electrolyte is suitable, through which cations, especially alkali cations, and preferably sodium cations, are removed from the side. SA / MK to the page S KK solid electrolytes can be transported. Such solid electrolytes are known to those skilled in the art and are described, for example, in DE 10 2015 013 155 A1, in WO 2012 / 048032 A2, paragraphs

[0035] ,

[0039] ,

[0040] , in US 2010 / 0044242 A1, paragraphs

[0040] ,

[0041] , and in DE 10360758 A1, paragraphs

[014] to

[025] . They are commercially marketed under the names NaSICON, LiSICON, and KSICON. A sodium ion-conducting solid electrolyte is preferred, and even more preferably, it has a NaSICON structure. NaSICON structures that can be used according to the invention are also described, for example, by N. Anantharamulu, K. Koteswara Rao, G. Rambabu, B. Vijaya Kumar, Velchuri Radha, M. Vithal, J Mater Sci 2011, 46, 2821-2837.

[0150] In a preferred embodiment of the partition wall W, the partition wallW included alkali cation-conducting solid electrolyte ceramics, and in particular the AFK FA , independently of each other a NaSICON structure of the formula MI< 1+2w+x-y+z M II< w M III< x Zr IV< 2-wxy MV< y (SiO 4 ) z (PO 4 ) 3-z emerged.

[0151] MI< is selected from Na +< , Li +< , preferably Na +< .

[0152] M II< is a divalent metal cation, preferably selected from Mg 2+< , Ca 2+< , Sr 2+< , Ba 2+< , Co 2+< , Ni 2+< , more preferably selected from Co 2+< , Ni 2+< .

[0153] M 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+< .

[0154] MV< is a pentavalent metal cation, preferably selected from V 5+< , Nb 5+< , Ta 5+< .

[0155] The Roman numerals I, II, III, IV, V indicate the oxidation states in which the respective metal cations exist.

[0156] w, x, y, z are real numbers, where 0 ≤ x < 2, 0 ≤ y < 2, 0 ≤ w < 2, 0 ≤ z < 3, and where w, x, y, z are chosen such that 1 + 2w + x - y + z ≥ 0 and 2 - w - x - y ≥ 0.

[0157] According to the invention, the NaSICON structure preferably has a structure of the formula Na (1 + v) Zr 2 Si v P (3 - v )O 12 , where v is a real number for which 0 ≤ v ≤ 3. Most preferably, v = 2.4

[0158] In a preferred embodiment of the partition wall W, in which these at least two AFKs FA , FB encompasses, all of which are separated from the partition wall W AFKs shared the same structure. 1.1.4.2 Separating element T

[0159] In the embodiments of the partition according to the invention W, in which these at least two AFKs FA , FBincludes the partition wall W preferably a separating element T. The separating element T According to the invention, at least two of the partition walls then separate at least two of them. W included alkali-cation-conducting solid electrolyte ceramics FA and FB , That means it is between at least two of the partition walls. W included alkali-cation-conducting solid electrolyte ceramics FA and FB arranged.

[0160] As a separating element T, which is preferably from the partition wall W Any body that allows the respective AFKs to be arranged separately from one another is suitable. The AFKs connect seamlessly to the separating element. T to avoid impairing the function of the partition in the electrolysis cell E The cathode chamber should be liquid-tightly separated from the adjacent middle or anode chamber.

[0161] The shape of the separating element T can be determined by a specialist depending on the number of AFKs that the partition wall W in the preferred embodiment, shall be selected.

[0162] The partition wall includes W For example, two or three AFKs can each be separated by a bridge arranged between the AFKs as a separating element. T be separated.

[0163] The partition wall includes W four or more AFKs can be separated by a separating element T, which has the shape of a cross or grid, can be separated.

[0164] In the embodiments of the partition according to the invention W, in which these at least two AFKs FA , FB It is particularly preferred that the partition wall W at least four AFKs and, even more preferably, that the separating element Tthen it is cross-shaped or grid-shaped, as this ensures that all three dimensions are fully available to the AFKs for thermal expansion / contraction.

[0165] The separating element T It can consist of a single piece. Then the AFK is seamlessly attached to the separating element, for example, using a method known to experts. T attached, for example via an adhesive, preferably using epoxy resins or phenolic resins. Alternatively or additionally, the separating element can T They can also be shaped in such a way that the respective AFK can be fitted or clamped into the partition element. This can already be done during the manufacturing of the partition. W be carried out accordingly.

[0166] In a preferred embodiment, in which the partition W a separating element includes, in particular, this between separating elements T and the AFKs, a seal The(Figures 3B, 3C). This ensures particularly well that the partition wall W It is liquid-tight. The seal The can be done by a specialist for the respective AFK or the respective separating element T be selected.

[0167] The seal The comprises in particular a material selected from the group consisting of elastomers, adhesives, preferably elastomers.

[0168] Suitable elastomers include, in particular, ethylene propylene diene monomer rubber ("EPDM"), fluoropolymer rubber ("FPM"), perfluoropolymer rubber ("FFPM"), and acrylonitrile butadiene rubber ("NBR").

[0169] In a further preferred embodiment, the separating element comprises T at least two parts T 1 and T 2 , which can be attached to each other and thus clamp the AFKs between them.

[0170] In this embodiment, it is particularly preferred to then use a separating element T and AFK another seal The to be installed to ensure a liquid seal.

[0171] The separating element T preferably comprises a material selected from the group consisting of plastic, glass, and wood. The separating element is particularly preferred. T made of plastic. Preferably, the plastic is selected from the group consisting of polypropylene, polystyrene, polyvinyl chloride, post-chlorinated polyvinyl chloride ("PVC-C"). 1.1.4.3 Frame element R

[0172] In a further preferred embodiment, the partition wall comprises W also a frame element R. The frame element R This differs from the separating element. T, that there is no space between the partition wall WThe frame element is arranged with alkali-cation-conducting solid electrolyte ceramics, meaning it does not separate them from each other. R particularly limits the surfaces O KK and OA / MK at least partially, preferably completely. This means in particular: The frame element R surrounds the surfaces O KK and OA / MK at least partially, preferably completely.

[0173] The frame element R can be part of the surfaces O KK and OA / MK Whether trained or not. The frame element is preferred. R as part of the surfaces O KK and OA / MK trained.

[0174] The frame element R is particularly about the surfaces O KK and OA / MK Directly contactable or not directly contactable, preferably directly contactable.

[0175] "Not directly contactable" means, with reference to the partition wall W Optional frame element included R, that the frame element R exclusively as at least part of the surfaces of those sides of the partition W trained, where it is not about the sides S KK and SA / MK in particular the frame element R then at least 1%, preferably at least 25%, more preferably at least 50%, even more preferably 100% of the surfaces of the sides of the partition W aus, which are not the pages S KK and S A / MK it.

[0176] "Directly contactable" means, with reference to the partition wall W Optional frame element included R, that part of the surfaces O KK and O A / MK through the surface of the frame element R is formed, that is, that the partition wall Wincluded frame element R on both surfaces O KK and O A / MK are directly accessible, so that it is on both surfaces O KK and O A / MK for example, it can be wetted with aqueous solution, alcoholic solution, alcohol or water.

[0177] For the arrangement of the frame element R in the partition wall W This means that there is then a way from the surface. O KK on the page S KK on the surface O A / MK on the page S A / MK there is one that is completely enclosed by the frame element R leads.

[0178] This includes the following embodiments: a part of the edge of the surfaces O KK and O A / MK is through the frame element R formed (as shown in Figures 4B, 4D); the edge of the surfaces O KK and O A / MK is completely enclosed by the frame element Rformed (as shown in Figures 4A, 4C, 7A, 7B);

[0179] The frame element can be used in this process. R additionally also as at least part of the surfaces of those sides of the partition W be trained, where it is not about the sides S KK and S A / MK in particular the frame element R at least 1%, preferably at least 25%, more preferably at least 50%, even more preferably 100% of the surfaces of the sides of the partition W from, where the pages are not S KK and S A / MK it.

[0180] In Fig. 4 B and Fig. 4 D For example, embodiments are shown in which the frame element R a part of the surfaces of those sides of the partition W trains, where the sides are not S KK and S A / MK it.

[0181] In Fig. 4 A and Fig. 4 C For example, embodiments are shown in which the frame element R the surfaces of those sides of the partition W, which are not the pages S KK and S A / MK deals, fully educates.

[0182] The frame element R It is made primarily from a material selected from the group consisting of plastic, glass, and wood. The frame element is particularly preferred. R made of plastic.

[0183] Even more preferred is a plastic selected from the group consisting of polypropylene, polystyrene, polyvinyl chloride, and PVC-C.

[0184] In another preferred embodiment, if the partition wall W a separating element T and a frame element R includes the frame element R and the separating element Tmade of the same material, or even more preferably both made of plastic, which is even more preferably selected from polypropylene, polystyrene, polyvinyl chloride, or PVC-C.

[0185] The frame element R It can consist of a single piece. Then the AFK is seamlessly attached to the frame element, for example, using a method known to experts. R It is attached, for example, using an adhesive, with epoxy resins and phenolic resins being particularly suitable. Alternatively or additionally, the frame element can be R It should also be shaped in such a way that the respective AFK fits into the frame element. R can be fitted or clamped in.

[0186] This also means that in the preferred embodiment, in which the partition W at least two AFKs F A , F B , at least one separating element T and a frame element R includes the AFKs, the at least one separating element Tand the frame element R connect seamlessly to one another.

[0187] Therefore, no gaps exist between the separating element. T, Frame element R and the AFKs enclosed by the partition W, through which glycol, glycolic solution, aqueous solution or water from the side S KK to the page S A / MK or vice versa.

[0188] In addition, especially if the partition wall W at least two AFKs F A , F B , a frame element R and at least one separating element T includes, and the frame element R and at least one separating element T are at least partially formed in one piece, the frame element R It consists of at least two parts that are attached to each other and clamp the AFKs between them. For example, the partition wall Wthen have a hinge at which the two parts of the frame element are joined R It can be folded up and down. Furthermore, the partition wall can W then have a lock to which the two parts of the frame element are attached. R lock in the folded position ( Abbildung 7 A) .

[0189] When folded, the AFKs and, if this is not already integrated with the frame element, R is formed, the separating element T between the two parts of the frame element R to be clamped. In this embodiment, a separating element can then be used. T and AFK or frame element R und AFK also requires a seal to be attached to ensure liquid tightness.

[0190] In a preferred embodiment, if the partition W at least two AFKs F A , F B , a frame element Rand at least one separating element T includes at least a part of the separating element T one-piece with at least one part of the frame element R formed. This means, in particular, that at least part of the separating element is then T into the frame element R transitions.

[0191] Preferably, the at least one separating element is located T and the frame element R then in one piece.

[0192] The embodiment of a frame element R This has the advantage that it is easier to assemble the electrolysis cell. E It can function as part of the exterior wall. This part of the partition wall W contacts the solutions in the respective interior I KK , I KA or I KM not, which is why it would be a waste to use at least one solid electrolyte ceramic for this part F A to take. Besides, that part of the partition wall W,which is clamped between the outer wall or forms part of it, is subjected to pressure, which causes the brittle solid electrolyte ceramic to deteriorate. F A This makes it unsuitable. Instead, a shatterproof and cheaper material is used for the frame. R selected. 1.1.4.4 Construction of the partition wall W

[0193] The partition wall W can be manufactured using methods known to those skilled in the art.

[0194] As a partition wall W In one embodiment of the method according to the invention, an AFK can be F A are used which are cut or shaped according to methods known to those skilled in the art.

[0195] The partition wall includes W a frame element R or at least one separating element T,The AFKs enclosed by the partition, possibly with seals, can be placed in a mold, and the partition element can be poured over liquid plastic and then allowed to solidify (injection molding process). Upon solidification, the plastic then encloses the AFKs.

[0196] Alternatively, the separating element T cast separately (or in parts) and then seamlessly attached to at least two AFKs (for example, glued). 1.1.4.5 Arrangement of the partition wall W in the electrolysis cell E

[0197] 1) The partition wall W is in the electrolysis cell E arranged so that the partition W comprised alkali-cation-conducting solid electrolyte ceramic F A the interior I KK on the page S KK over the surface O KK contacted directly.

[0198] If the partition wall W at least two AFKs F A , F B , at least one separating element Tand, if necessary, a frame element R The partition wall is included W in the electrolysis cell E arranged so that the partition W included alkali-cation-conducting solid electrolyte ceramics F A and F B and preferably also the separating element T, the interior I KK on the page S KK over the surface O KK contact us directly.

[0199] This means that the partition W in the electrolysis cell E is arranged so that, when the interior I KK on the page S KK with solution L 2 is completely filled, that the solution L 2 then over the surface O KK at least those from the partition wall W comprised alkali-cation-conducting solid electrolyte ceramic F A contacted, so that ions (e.g. alkali metal ions such as sodium, lithium) from F A into the solution L 2 can enter.

[0200] If the partition wall W at least two AFKs F A , F B , at least one separating element T and, if necessary, a frame element R encompasses, this means that the partition W in the electrolysis cell E is arranged so that, when the interior I KK on the page S KK with solution L 2 is completely filled, that the solution L 2 then over the surface O KK at least the two from the partition wall W included alkali-cation-conducting solid electrolyte ceramics F A and F B and preferably also the separating element T so contacted that ions (e.g. alkali metal ions such as sodium, lithium) from F A and F B , into the solution L 2 can enter.

[0201] 2) Additionally, the partition wall Win the embodiments in which the electrolysis cell E no middle chamber K M includes, for example, the electrolysis cell E arranged that the partition wall W comprised alkali-cation-conducting solid electrolyte ceramic F A the interior I KA on the side S A / MK over the surface O A / MK contacted directly.

[0202] If the partition wall W at least two AFKs F A , F B , at least one separating element T and, if necessary, a frame element R includes, and if the electrolysis cell E no middle chamber K M encompasses, this means that the partition W so in the electrolysis cell E is arranged so that the partition wall W comprised alkali cation-conducting solid electrolyte ceramics, and preferably also the separating element T, the interior I KA on the page S A / MK over the surface O A / MK contact us directly.

[0203] This means the following: in the embodiments in which the electrolysis cell E no middle chamber K M The partition wall encompasses, borders W to the interior I KA the anode chamber K A .

[0204] In these embodiments, the partition wall W in the electrolysis cell E, it is arranged such that, when the interior I KA on the page S A / MK with solution L 3 completely filled, that the solution L 3 then over the surface O A / MK at least the alkali-cation-conducting solid electrolyte ceramic enclosed by the partition W F A contacted, so that ions (e.g. alkali metal ions such as sodium, lithium) from the solution L 4 into the AFK F A can enter.

[0205] If the partition wall W at least two AFKs F A , F B , at least one separating element T and, if necessary, a frame element R If this includes, it means that the partition wall W in the electrolysis cell E is arranged so that, when the interior I KA on the page S A / MK with solution L 3 is completely filled, that the solution L 3 then over the surface O A / MK at least the two from the partition wall W included alkali-cation-conducting solid electrolyte ceramics F A and F B and preferably also the separating element T so contacted that ions (e.g. alkali metal ions such as sodium, lithium) are released from the solution L 3 into the AFK F A and F B can enter.

[0206] 3) Additionally, the partition wall W in cases where the electrolysis cell E at least one middle chamber K M comprises, arranged in the electrolysis cell E, such that the partition W included alkali-cation-conducting solid electrolyte ceramics F A the interior I KM on the page S A / MK over the surface O A / MK contacted directly.

[0207] If the partition wall W at least two AFKs F A , F B , at least one separating element T and, if necessary, a frame element R includes, and if the electrolysis cell E at least one middle chamber K M encompasses, this means that the partition W so in the electrolysis cell E is arranged so that the partition wall W comprised alkali cation-conducting solid electrolyte ceramics, and preferably also the separating element T, the interior I KM on the page S A / MK over the surface O A / MK contact us directly.

[0208] This means the following: in the embodiments in which the electrolysis cell E at least one middle chamber K M The partition wall encompasses, borders W to the interior I KM the middle chamber K M .

[0209] In these embodiments, the partition wall W in the electrolysis cell E then arranged so that, when the interior I KM is on the side S A / MK with solution L 3 is completely filled, that the solution L 3 then over the surface O A / MK at least those from the partition wall W comprised alkali-cation-conducting solid electrolyte ceramic F A contacted, so that ions (e.g. alkali metal ions such as sodium, lithium) from the solution L 3 into the AFK F A can enter.

[0210] If the partition wall W at least two AFKs F A , F B , at least one separating element Tand, if necessary, a frame element R If this includes, it means that the partition wall W in the electrolysis cell E is arranged so that, when the interior I KM on the page S A / MK with solution L 3 is completely filled, that the solution L 3 then over the surface O A / MK at least the two from the partition wall W included alkali-cation-conducting solid electrolyte ceramics F A and F B and preferably also the separating element T so contacted that ions (e.g. alkali metal ions such as sodium, lithium) are released from the solution L 3 into the AFK F A and F B can enter.

[0211] In a preferred embodiment of the electrolysis cell E contact at least 50%, in particular at least 70%, preferably at least 90%, most preferably 100% of the surface area O KK , which is formed by AFKs, the interior I KK .

[0212] In a preferred embodiment of the electrolysis cell E Without a central chamber, contact must occur with at least 50%, in particular at least 70%, preferably at least 90%, most preferably 100% of the surface area. O A / MK , which is formed by AFKs, the interior I KA .

[0213] In a preferred embodiment of the electrolysis cell E with at least one central chamber contacting at least 50%, in particular at least 70%, preferably at least 90%, most preferably 100% of the surface area O A / MK , which is formed by AFKs, the interior I KM . 1.2 Schritt (a) des erfindungsgemäßen Verfahrens

[0214] Step (a) of the process according to the invention relates to the preparation of a solution L 1 of MA glycolate in glycol, wherein MA is an alkali metal cation. The process is carried out in an electrolysis cell E.

[0215] Preferably, MA is selected from the group consisting of Li< , K< , Na< , more preferably from the group consisting of K< , Na< . Most preferred is MA = Na< . 1.2.1 Inventive method in an electrolysis cell E without middle chamber K M

[0216] In cases where the electrolysis cell E has no central chamber K M The steps (α1), (α2), (α3) that run simultaneously are included. 1.2.1.1 Schritt (α1)

[0217] In step (α1) a solution is L 2 comprising glycol, preferably comprising an alkali metal glycolate MA -glycolate and glycol, passed through I KK.

[0218] The solution L 2 is preferably free of water. According to the invention, "free of water" means that the weight of the water in the solution is... L 2 relative to the weight of the glycol in the solution L 2 (Mass ratio) ≤ 1 : 10, preferred ≤ 1 : 20, even more preferred ≤ 1 : 100, even more preferred ≤ 0.5 : 100, even more preferred ≤ 1 : 1000, even more preferred ≤ 1 : 10000.

[0219] If the solution L2 contains MA-glycolate, then the mass fraction of MA-glycolate in the solution L2 is, relative to the total solution L 2 , especially at > 0 to 30 wt.%, preferably at 0.1 to 20 wt.%, even more preferably at 0.2 to 10 wt.%, even more preferably at 0.5 to 5 wt.%, most preferably at 0.7 to 2 wt.%, most preferred at 1 wt.%.

[0220] Does the solution include L 2 MA -glycolate, so it is in the solution L 2 in particular the mass ratio of MA glycolate to glycol in the range of 1 : 1000 to 1 : 5, preferably in the range of 1 : 250 to 3 : 20, even more preferably in the range of 1 : 120 to 1 : 8, and even more preferably at 1 : 100. 1.2.1.2 Schritt ( α 2)

[0221] In step (α2) a neutral or alkaline aqueous solution is used. L 3 a salt S comprehensive MA as cation by I KA guided.

[0222] The salt S is preferably a halide, sulfate, sulfite, nitrate, hydrogen carbonate or carbonate of MA, more preferably a halide.

[0223] Halides are fluorides, chlorides, bromides, and iodides. The most common halide is chloride.

[0224] The pH of the aqueous solution L 3 where ≥ 7.0, preferably in the range 7 to 12, more preferably in the range 8 to 11, even more preferably 10 to 11, most preferably at 10.5.

[0225] The mass fraction of the salt S in the solution L 3 The concentration is preferably in the range of > 0 to 20 wt.%, preferably 1 to 20 wt.%, more preferably 5 to 20 wt.%, even more preferably 10 to 20 wt.%, and most preferably 20 wt.%, based on the entire solution. L 3 . 1.2.1.3 Schritt (α3)

[0226] In step (α3) a voltage is then applied between E A and E K created.

[0227] This results in current flow from the charge source to the anode, charge flow via ions to the cathode, and finally current flow back to the charge source. The charge source is known to those skilled in the art and is typically a rectifier that converts alternating current into direct current and can generate specific voltages via voltage converters.

[0228] This in turn has the following consequences: during the process A KK will the solution L 1 obtained, whereby the concentration of MA glycolate in L 1 is higher than in L 2 , during the process A KA An aqueous solution L4 of S is obtained, where the concentration of S in L 4 is lower than in L 3 .

[0229] In step (α3) of the inventive method, a voltage is applied such that a current flows such that the current density (= ratio of the current flowing to the electrolysis cell to the area of ​​the solid electrolyte, which is in I KA (contacting the anolyte located inside) is in the range of 10 to 8000 A / m², preferably in the range of 100 to 2000 A / m², more preferably in the range of 300 to 800 A / m², and even more preferably at 494 A / m². This can be determined by a person skilled in the art using standard methods. The area of ​​the solid electrolyte that contacts the anolyte in the interior I KA the anode chamber K A the anolyte in contact with the anolyte is in particular 0.00001 to 10 m², preferably 0.0001 to 2.5 m², more preferably 0.0002 to 0.15 m², and even more preferably 2.83 cm².

[0230] It goes without saying that step (α3) of the method according to the invention is carried out when the interior I KA the anode chamber K A at least partially with L 3 is loaded and the interior I KK the cathode chamber K K with L 2 is at least partially loaded, so that both L 3 as well as L 2 the partition wall W included contacting AFKs and especially the separating element T, when the partition wall W ein This includes contacting us.

[0231] The fact that in step (α3) a charge transport takes place between E A and E K takes place implies that I KK and I KA simultaneously with L 2 or L 3 are loaded in such a way that they block the electrodes E K or E A Cover it enough to close the circuit.

[0232] This is particularly the case when there is a continuous flow of liquid. L 3 through I KA and a fluid flow of L 2 through I KK is guided and the fluid flow of L 3 the electrode E A and the fluid flow of L 2 the electrode E K at least partially, preferably completely covered.

[0233] In a further preferred embodiment, the method according to the invention is carried out continuously, i.e., step (α1) and step (α2) are carried out continuously and voltage is applied according to step (α3).

[0234] After completing step (α3), the process will be updated. A KK the solution L 1 obtained, whereby the concentration of MA glycolate in L 1 is higher than in L 2 . If L 2 already included MA glycolate, the concentration of MA glycol in L 1 preferably 1.01 to 200.2 times higher, more preferably 5.04 to 100.8 times higher, even more preferably 10.077 to 50.4 times higher, and still more preferably 18.077 to 20.08 times higher than in L 2 ,preferably 20,000 times higher than in L 2 , with the mass fraction of MA glycolate being even more preferred in this case L 1 and in L 2 in the range of 0.1 to 50 wt.%, or even more preferably 1 to 20 wt.%.

[0235] The process A KA an aqueous solution L 4 from S obtained, whereby the concentration of S in L 4 is lower than in L 3 .

[0236] The concentration of the cation MA in aqueous solution L 3 is preferably in the range of 0.5 to 5 mol / l, more preferably 1 mol / l. The concentration of the cation MA in aqueous solution L 4 is preferably 0.5 mol / l lower than that of the respective aqueous solutions used. L 3 .

[0237] In particular, steps (α1) to (α3) of the inventive method are carried out at a temperature of 20 °C to 110 °C, preferably 50 °C to 105 °C, more preferably 80 °C to 99 °C, even more preferably 90 °C to 95 °C and a pressure of 0.5 bar to 1.5 bar, more preferably 0.9 bar to 1.1 bar, more preferably 1.0 bar.

[0238] During the execution of steps (α1) to (α3) of the inventive method, the following occurs in I KK typically hydrogen, which is released via the process A KK from the cell together with the solution L 1 can be removed. The mixture of hydrogen and solution L 1 In a particular embodiment of the present invention, it can then be separated according to a method known to those skilled in the art. I KA , If the alkali metal compound used is a halide, especially a chloride, chlorine or another halogen gas can be produced, which can then be released via the process. A KK from the cell together with the solution L 4 can be removed. Oxygen and / or carbon dioxide can also be produced, which can likewise be removed. The mixture of chlorine, oxygen and / or CO₂ and solution L 4 In a particular embodiment of the present invention, the solution can then be separated according to a method known to those skilled in the art. Similarly, after separation of the gases chlorine, oxygen and / or CO₂ from the solution, the solution can be separated. L 4 These are separated from each other using methods known to those skilled in the art. 1.2.2 Inventive method in an electrolysis cell E with middle chamber K M

[0239] In cases where the electrolysis cell E at least one middle chamber K M The steps (β1), (β2), (β3) that occur simultaneously are carried out.

[0240] It is preferred that the electrolysis cell E at least one middle chamber K M includes, and then the simultaneously running steps (β1), (β2), (β3) are carried out. 1.2.2.1 Schritt (β1)

[0241] In step (β1) a solution is L 2 comprising glycol, preferably comprising an alkali metal glycolate MA -glycolate and glycol, passed through I KK.

[0242] The solution L 2 is preferably free of water. According to the invention, "free of water" means that the weight of the water in the solution is... L 2 relative to the weight of the glycol in the solution L 2 (Mass ratio) ≤ 1 : 10, preferred ≤ 1 : 20, even more preferred ≤ 1 : 100, even more preferred ≤ 0.5 : 100.

[0243] Does the solution include L 2 MA-glycolate, so the mass fraction of MA-glycolate in the solution is L 2 , referring to the entire solution L 2 ,especially at > 0 to 30 wt.%, preferably at 0.1 to 20 wt.%, even more preferably at 0.2 to 10 wt.%, even more preferably at 0.5 to 5 wt.%, most preferably at 0.7 to 2 wt.%, most preferred at 1 wt.%.

[0244] Does the solution include L 2 MA -glycolate, so it is in the solution L 2 in particular the mass ratio of MA glycolate to glycol in the range of 1 : 1000 to 1 : 5, preferably in the range of 1 : 250 to 3 : 20, even more preferably in the range of 1 : 120 to 1 : 8, and even more preferably at 1 : 100. 1.2.2.2 Schritt (β2)

[0245] In step (β2) a neutral or alkaline aqueous solution is used. L 3 a salt S comprehensive MA as cation by I KM , then about V AM , then guided through I KA.

[0246] The salt S is preferably a halide, sulfate, sulfite, nitrate, hydrogen carbonate or carbonate of MA, more preferably a halide.

[0247] Halides are fluorides, chlorides, bromides, and iodides. The most common halide is chloride.

[0248] The pH of the aqueous solution L 3 where ≥ 7.0, preferably in the range 7 to 12, more preferably in the range 8 to 11, even more preferably 10 to 11, most preferably at 10.5.

[0249] The mass fraction of the salt S in the solution L 3 The concentration is preferably in the range of > 0 to 20 wt.%, preferably 1 to 20 wt.%, more preferably 5 to 20 wt.%, even more preferably 10 to 20 wt.%, and most preferably 20 wt.%, based on the entire solution. L 3 . 1.2.2.3 Schritt (β3)

[0250] In step (β3) a voltage is then applied between E A and E K created.

[0251] This results in current flow from the charge source to the anode, charge flow via ions to the cathode, and finally current flow back to the charge source. The charge source is known to those skilled in the art and is typically a rectifier that converts alternating current into direct current and can generate specific voltages via voltage converters.

[0252] This in turn has the following consequences: during the process A KK will the solution L 1 obtained, whereby the concentration of MA glycolate in L 1 is higher than in L 2 , at the process A KA an aqueous solution L 4 from S obtained, whereby the concentration of S in L 4 is lower than in L 3 .

[0253] In step (β3) of the inventive method, a voltage is applied such that a current flows such that the current density (= ratio of the current flowing to the electrolysis cell to the area of ​​the solid electrolyte, which is in I KM The current (contacted with the anolyte located in the central chamber) is in the range of 10 to 8000 A / m², preferably in the range of 100 to 2000 A / m², more preferably in the range of 300 to 800 A / m², and even more preferably at 494 A / m². This can be determined by a person skilled in the art using standard methods. The area of ​​the solid electrolyte that contacts the anolyte in the central chamber K M The area of ​​contact with the anolyte is in particular 0.00001 to 10 m², preferably 0.0001 to 2.5 m², more preferably 0.0002 to 0.15 m², and even more preferably 2.83 cm².

[0254] It goes without saying that step (β3) of the method according to the invention is then carried out when the interiors I KA and I KM both chambers K M and K A at least partially with L 3 are loaded and the interior I KK with L 2 is at least partially loaded, so that both L 3 as well as L 2 the partition wall W included solid electrolytes contact and in particular also the separating element T, when the partition wall W ein This includes contacting us.

[0255] The fact that in step (β3) a charge transport takes place between E A and E K takes place implies that I KK , I KM and I KA simultaneously with L 2 or L 3 are loaded in such a way that they block the electrodes E K or E A Cover it enough to close the circuit.

[0256] This is particularly the case when there is a continuous flow of liquid. L 3 through I KM , V AM and I KP , and a fluid stream of L 2 through I KK is directed and the liquid flow from L 3 passes through the electrode E A and the liquid flow from L2 to the electrode E K at least partially, preferably completely covered.

[0257] In a further preferred embodiment, the method according to the invention is carried out continuously, i.e., step (β1) and step (β2) are carried out continuously and voltage is applied according to step (β3).

[0258] After completing step (β3), the process will be updated. A KK the solution L 1 obtained, whereby the concentration of MA glycolate in L 1 is higher than in L 2 . If L 2 already included MA glycolate, the concentration of MA glycol in L 1 preferably 1.01 to 200.2 times higher, more preferably 5.04 to 100.80 times higher, even more preferably 10.077 to 50.40 times higher, and still more preferably 18.077 to 20.08 times higher than in L 2 ,preferably 20,000 times higher than in L 2 , where the mass fraction of MA glycolate is even more preferred L 1 and in L 2 in the range of 0.1 to 50 wt.%, or even more preferably 1 to 20 wt.%.

[0259] The process A KA an aqueous solution L 4 from S obtained, whereby the concentration of S in L 4 is lower than in L 3 .

[0260] The concentration of the cation MA in the aqueous solution L 3 The concentration of the cation MA is preferably in the range of 0.5 to 5 mol / l, more preferably 1 mol / l. L 4 is preferably 0.5 mol / l lower than that of the respective aqueous solution used. L 3 .

[0261] In particular, steps (β1) to (β3) of the inventive method are carried out at a temperature of 20 °C to 110 °C, preferably 50 °C to 105 °C, more preferably 80 °C to 99 °C, even more preferably 90 °C to 95 °C and a pressure of 0.5 bar to 1.5 bar, more preferably 0.9 bar to 1.1 bar, more preferably 1.0 bar.

[0262] During the execution of steps (β1) to (β3) of the process according to the invention, hydrogen is typically produced in the cathode chamber I KK, which is then carried out via the process A KK from the cell together with the solution L 1 can be removed. The mixture of hydrogen and solution L 1 In a particular embodiment of the present invention, it can then be separated according to a method known to those skilled in the art. I KA , If the alkali metal compound used is a halide, especially a chloride, chlorine or another halogen gas can be produced, which can then be released via the process. A KKfrom the cell together with the solution L 4 can be removed. Oxygen and / or carbon dioxide can also be produced, which can likewise be removed. The mixture of chlorine, oxygen and / or CO₂ and solution L 4 In a particular embodiment of the present invention, the solution can then be separated according to a method known to those skilled in the art. Similarly, after separation of the gases chlorine, oxygen and / or CO₂ from the solution, the solution can be separated. L 4 These are separated from each other using methods known to those skilled in the art. 1.2.2.4 Additional advantages of steps (β1) to (β3)

[0263] This implementation of steps (β1) to (β3) brings further surprising advantages that were not expected in light of the prior art. Steps (β1) to (β3) of the process according to the invention protect the acid-labile solid electrolyte from corrosion without having to sacrifice alcoholate solution from the cathode compartment as a buffer solution, as is the case in the prior art. Thus, the process according to the invention is more efficient than the procedure described in WO 2008 / 076327 A1, in which the product solution is used for the central chamber, which reduces the overall conversion. Step 2 (b): Implementation of PET with solution L 1 <21>

[0264] In step (b) of the method according to the invention, the solution L 1 obtained in step (a) is <21> comprehensive glycol and MA glycolate with PET to a mixture M 1 comprehensive BHET implemented. 2.1 PET starting material

[0265] As PETwhich is used in step (b) of the method according to the invention, can be any PET which must be depolymerized. Typically, such PET as waste, especially in households, industry or agriculture.

[0266] In one embodiment of the process according to the invention, the material to be depolymerized is located PET in a mixture with other plastics, in particular at least one plastic selected from polyethylene ("PE") or polyvinyl chloride ("PVC"). This is typically the case when, in the process according to the invention, PET is to be depolymerized from plastic waste. In this embodiment, the PET at least partially separated from the other plastics, preferably by sorting, before being subjected to step (b) of the inventive method.

[0267] In one embodiment of the method according to the invention, the PET exposed to at least one pretreatment step.

[0268] Such pretreatment steps are described, for example, in DE 10032899 C2.

[0269] According to the invention, the PET at least one pretreatment step selected from a chemical pretreatment step, a comminution step, is subjected to before it is used in step (b).

[0270] In cases where the PET when present in a mixture with other plastics PET preferably undergoes at least one pretreatment step selected from at least partial separation from other plastics, preferably by sorting, chemical pretreatment step, comminution step, before being used in step (b).

[0271] In cases where the PET when present in a mixture with other plastics PETpreferably first separated at least partially from other plastics, then chemically pretreated at least once and finally crushed.

[0272] The chemical pretreatment step is primarily a washing step. Such a washing step has the advantage of removing any impurities, particularly food residues, cosmetic residues, and / or bodily secretions (e.g., blood, semen, feces), before step (b) is carried out. Such impurities could reduce the efficiency of the reaction in step (b) and / or the purity of the resulting product. BHET worsen.

[0273] In the chemical pretreatment step, in particular the washing step, the waste is heated, in particular in a washing solution, at a temperature of 30 °C to 99 °C, preferably 50 °C to 90 °C, more preferably 70 °C to 85 °C.

[0274] Typical washing solutions are familiar to the professional and are preferably selected from: Aqueous solution of a surfactant, preferably a non-ionic surfactant; aqueous solution of an alkali metal hydroxide or alkaline earth metal hydroxide; preferably aqueous NaOH.

[0275] The treatment time of the chemical pretreatment step, in particular the washing step, is preferably 1 min to 12 h, preferably 10 min to 6 h, more preferably 30 min to 2 h, even more preferably 45 to 90 min, most preferably 60 min.

[0276] After the treatment of PET In the chemical pretreatment step, especially the washing step, the aqueous solution is separated, e.g. by filtration, and the purified PET Preferably washed at least once with water to remove any residue of the washing solution.

[0277] The resulting PET waste is then dried, in particular in a drying oven. The drying temperature is preferably in the range of 30 to 120 °C, more preferably 50 to 100 °C, more preferably 60 to 90 °C, and most preferably 80 °C.

[0278] The comminution step has the advantage that the surface area available for the reaction in step (b) is reduced. PET The reaction rate in step (b) is increased. This increases the reaction rate of the conversion. The comminution can be carried out in apparatus known to those skilled in the art, for example a shredder or a cutting mill.

[0279] In a further embodiment of the method according to the invention, the PET Before being subjected to step (b), it is decolorized or selectively colored. This can be done using methods known to those skilled in the art, e.g. decolorization with hydrogen peroxide or coloring with a dye. 2.2 Implementation conditions

[0280] The implementation of the PET with a solution L 1 <21> comprehensive glycol and MA glycolate to a mixture M 1 This can then be done under conditions familiar to the expert.

[0281] The implementation in step (b) is preferably carried out until at least a certain time tb has been reached. P = 10%, preferably at least P = 20%, preferably at least P = 25%, preferably at least P = 30%, preferably at least P = 40%, preferably at least P = 50%, preferably at least P = 60%, preferably at least P = 70%, preferably at least P = 80%, preferably at least P = 90%, preferably at least P = 95%, or even more preferably at least P = 99% of the amount used in step (b) PETs have implemented.

[0282] This percentage P is calculated according to the following formula: P = n TS + n MHET + n BHET / n PET .

[0283] Here, n PET is the amount of substance of repeat units of the following structure (Ξ) in the sample used in step (b). PET:

[0284] n TS is the amount of substance at TS, which have formed from the beginning of step (b) until time tb in step (b).

[0285] n MHET is the amount of substance at MHET, which have formed from the beginning of step (b) until time tb in step (b).

[0286] n BHET is the amount of substance at BHET, which have formed from the beginning of step (b) until time tb in step (b).

[0287] The structures of the connections BHET, MHET, TS are as follows: "MHET" This also includes the corresponding carboxylate of the structure shown.

[0288] " TS" also includes the corresponding mono- and dicarboxylate of the structure shown.

[0289] The conversion in step (b) is carried out in particular at a temperature of at least 100 °C, preferably at a temperature in the range of ≥ 100 °C to ≤ 197 °C, more preferably at a temperature in the range of ≥ 130 °C to ≤ 197 °C, more preferably at a temperature in the range of ≥ 150 °C to ≤ 197 °C, more preferably at a temperature in the range of ≥ 175 °C to ≤ 197 °C.

[0290] The reaction in step (b) is preferably carried out at the boiling point of the glycol. Even more preferably, the glycol is refluxed, i.e., glycol is evaporated from the reaction, condensed, and then returned to the reaction. This refluxation can be controlled using methods familiar to those skilled in the art, for example, in a distillation apparatus.

[0291] The total weight of the MA glycolate used in the process, in relation to the total weight of the material used in the process PETs The percentage is particularly in the range of 0.1 to 100 wt.%, preferably in the range of 0.5 to 80 wt.%, more preferably in the range of 1.0 to 50 wt.%, more preferably in the range of 1.5 to 25 wt.%, more preferably in the range of 2.0 to 10 wt.%, more preferably in the range of 2.5 to 6.0 wt.%, particularly preferably in the range of 3.5 to 5.0 wt.%, most preferably in the range of 3.9 wt.%.

[0292] The implementation can be carried out using equipment familiar to professionals.

[0293] After completion of step (b) of the process according to the invention, a mixture M 1 is obtained in which the molar ratio η of the amount of substance of BHET (n BHET ) to the sum of the amounts of substance of MHET and TS(n MHET + n TS ) in the range 1 : 1 to 1000 : 1, preferably 2 : 1 to 500 : 100, more preferred 4 : 1 to 300 : 1, even more preferred 10 : 1 to 100 : 1, even more preferred 13 : 1 to 60 : 1, even more preferred 13 : 1 to 24 : 1. η = n BHET / n MHET + n TS 2.3 Preferred step (c)

[0294] In a preferred further step (c) BHET at least partially from M 1 separated. This is preferably done by crystallization and / or distillation. Even more preferably BHET in step (c) from M 1 filtered and then crystallized. 3. Methods for recycling PET

[0295] The mixture in the process according to the invention M 1 received BHET is preferably used in a process for recycling polyethylene terephthalate in one step (ζ) to PET polymerized.

[0296] This polymerization is known to those skilled in the art as "polycondensation" and is described, for example, in EP 0 723 951 A1 and by Th. Rieckmann and S. Völker in Chapter 2 "Poly(Ethylene Terephthalate) Polymerization - Mechanism, Catalysis, Kinetics, Mass Transfer and Reactor Design" on page 92 of the book "Modern Polyesters: Chemistry and Technology of Polyesters and Copolyesters. Edited by J. Scheirs and TE Long, 2003, John Wiley & Sons, Ltd ISBN: 0-471-49856-4".

[0297] In particular, this will be done BHET in step (ζ) in the presence of catalysts, in particular catalysts selected from the group consisting of antimony compounds, preferably Sb₂O₃, to be again PET polymerized.

[0298] The polymerization of is preferred BHET to PETStep (ζ) is carried out at least at the boiling point of the glycol. In particular, during the polymerization in step (ζ), glycol is removed from the reaction mixture to shift the reaction equilibrium towards the polymer. PET to postpone.

[0299] The polymerization of is preferred BHET to PET The polymerization in step (ζ) is carried out at the boiling point of the glycol. Even more preferably, glycol is removed from the reaction mixture during the polymerization in step (ζ) to shift the reaction equilibrium towards the polymer. PET to postpone.

[0300] This is achieved in particular by distillation at a pressure < 1 bar, preferably 0.1 mbar, at the simultaneous boiling point of the glycol at the respective pressure. Examples 1. Inventive example E1: 1.1 Production of glycolic sodium glycolate solution by electrolysis 1.1.1 Experimental setup

[0301] The electrolytic production of sodium glycolate was carried out in a three-chamber electrolysis cell.

[0302] The middle chamber was separated from the anode chamber by a filter cloth and from the cathode chamber by a 15 x 15 cm Nasicon ceramic.

[0303] A DSA anode was used as the anode [" dimensionally stable anode"; A titanium anode coated with ruthenium oxide / iridium oxide (RuO 2 + IrO 2 / Ti) was used, the cathode was made of stainless steel (VA means "rustproof"; stainless steel).

[0304] A Gamry Reference 3000 (AE) potentiostat and a Reference 30K Booster were used as the voltage source.

[0305] The cathode chamber of the electrolysis cell was connected to a 250 ml heated double-jacketed vessel with a magnetic stirrer. Electrolyte could be pumped from this vessel via a peristaltic pump, through a conductivity measuring point, and into the cathode chamber of the electrolysis cell via a further 100 ml glass heat exchanger. From there, the catholyte could be pumped back into the double-jacketed vessel. The catholyte was thus circulated.

[0306] The temperature of the cathode-side electrolyte could be measured or adjusted via a thermostat with a PT 100 sensor (platinum sensor, which has a nominal resistance of 100 Ω at a temperature of 0 °C) and a heat exchanger.

[0307] The central chamber of the electrolysis cell was connected to a reservoir, from which electrolyte could be pumped via a peristaltic pump into the central chamber, then via the filter cloth into the anode chamber, and from there via a pH measuring point into a collection vessel.

[0308] The temperature of the anode-side electrolyte could be measured and adjusted via a thermostat with a PT100 sensor and / or heat exchanger. The anolyte was not recirculated. 1.1.2 Experimental procedure:

[0309] The thermostat for the cathode side was set to 90°C and started. 650 g of 1 wt% sodium glycolate solution were added to the heated double-jacketed vessel, and the peristaltic pump was started (flow rate 1000 ml / h). This pumped the sodium glycolate solution through a conductivity sensor and another heat exchanger into the cathode chamber of the electrolysis cell. From the cathode chamber, the glycolate then flowed back into the double jacket. The glycolate and the chamber were thus heated to 90°C. The thermostat for the NaCl side was set to 105°C, and the peristaltic pump for the NaCl brine was started (flow rate 4000 ml / h). The 20 wt% NaCl brine with pH 11 from a storage vessel was pumped through a heat exchanger into the central chamber of the electrolysis cell. From there, it flowed through the filter cloth into the anode chamber, then from the cell into a pH measuring point, and then into the collection vessel. The NaCl brine was not recirculated.Once the cathode chamber had heated to 90 °C and the anode side at the pH measuring point had reached a temperature of 80 °C, the electrolysis cell was switched on. For this, the potentiostat was switched to galvanostatic operation. The current was set to a fixed 10 amperes, and the voltage was adjusted accordingly. Then, the conductivity measurement of the glycolate and the pH measurement of the NaCl solution were recorded.

[0310] Every 20 seconds, current, voltage, glycolate temperature, glycolate conductivity, brine pH, and brine temperature were recorded. The hydrogen and chlorine produced were extracted. The chlorine was neutralized with NaOH in gas washing bottles.

[0311] The electrolysis process lasted 4 hours. Then the current was switched off and the cell was completely emptied.

[0312] The sodium glycolate solution had a concentration of approximately 20% by weight. 1.2 Depolymerization of PET with glycolic sodium glycolate solution from electrolysis

[0313] In the process according to the invention, 100 g were used. PET The solution was placed in an autoclave containing 800 g of ethylene glycol. The solution was then heated to 150 °C with stirring. Once the temperature of 150 °C was reached, 19.5 g of 20% sodium glycolate solution in ethylene glycol (corresponding to 0.046 mol) from the electrolysis were added. The reaction was carried out for five hours, and the reactor output was examined after cooling. The conversion obtained was... BHET (1) and mono-2-hydroxyethyl terephthalic acid (= " MHET ") (2) and terephthalic acid (= " TS (3) is in the Figure 8 represented (determined by gas chromatography; in % conversion based on the repeating unit of the structure (Ξ) of the substance used PETs; thin hatching " / / / / "). 2. Comparative example V1:

[0314] In a comparative experiment, 100 g were used. PETThe solution was placed in an autoclave containing 800 g of ethylene glycol. The solution was then heated to 150 °C while stirring. The reaction was carried out for five hours, and the reactor output was examined after cooling. The conversion of BHET (1) and MHET (2) TS (3) is in the Figure 8 shown (black, "■"). 3. Comparative example V2:

[0315] In a comparative experiment, 100 g are used. PET The solution was placed in an autoclave containing 800 g of ethylene glycol. The solution was then heated to 150 °C with stirring. Once the temperature of 150 °C was reached, 3.7 g of 50% NaOH solution in water (corresponding to 0.046 mol) were added. The reaction was carried out for five hours, and the reactor output was examined after cooling. The conversion obtained was... BHET (1) and MHET (2) TS (3) is in the Figure 8 shown (bold hatching: " / / / / "). 4. Result

[0316] Comparing salaries to BHET, MHET and TS in the depolymerized product in the inventive example E1 and the comparative examples V1, V2 shows (see Fig. 8 ) that a higher proportion of the depolymerization occurs when using the electrolytically obtained glycolic sodium glycolate solution. BHET This is advantageous because it makes more product available, which can be directly used in a polycondensation reaction to form a new product. PET can be implemented. 6. Reference symbols in the illustrations

[0317] Electrolysis cell E <1> Anode chamber KA <11> Inflow Z KA <110> Sequence A KA <111> interior I KA <112> anodic electrode EA <113> Cathode chamber KK <12> Inflow Z KK <120> Sequence A KK <121> interior I KK <122> cathodic electrode EK <123> Middle chamber KM <13> Inflow Z KM <130> Sequence A KM <131> interior I KM <132> diffusion barrier D <14> Connection V AM <15> partition W <16> Page S KK <161> Page SA / MK <162> surface O KK <163> surface OA / MK <164> Separating element T <17> Part of a separating element <171> Part of a separating element <172> Solid electrolyte ceramic FA <18> Solid electrolyte ceramic FB <19> Solid electrolyte ceramic FC <28> Solid electrolyte ceramic FD <29> Solid electrolyte ceramics FE, FF, FG, FH, FI <30>, <31>, <32>, <33>, <34> Frame element R <20> frame part <201> frame part <202> seal Di <40> hinge <50> Lock <60> Exterior wall WA <80> Solution containing MA glycolate in glycol L 1 <21> Solution containing glycol L 2 <22> neutral or alkaline aqueous solution of a salt S comprehensive MA as cation L 3 <23> aqueous solution of S, where [S] L4 < [S] L3 . L 4 <24>

Claims

1. Method of depolymerization of polyethylene terephthalate PET, comprising the following steps: (a) producing a solution L1 <21> of MA glycolate in glycol, where MA is an alkali metal cation, in an electrolysis cell E <1> comprising - at least one anode chamber KA <11> having at least one inlet ZKA <110>, at least one outlet AKA <111>, and an interior IKA <112> comprising an anodic electrode EA <113>, - at least one cathode chamber KK <12> having at least one inlet ZKK <120>, at least one outlet AKK <121>, and an interior IKK <122> comprising a cathodic electrode EK <123>, - and optionally at least one interposed middle chamber KM <13> having at least one inlet ZKM <130>, at least one outlet AKM <131> and an interior IKM <132>, wherein IKA <112> and IKM <132> are then divided from one another by a diffusion barrier D <14>, and AKM <131> is connected by a connection VAM <15> to the inlet ZKA <110>, such that liquid can be passed from IKM <132> into IKA <112> via the connection VAM <15>, wherein - in the cases in which the electrolysis cell E <1> does not comprise a middle chamber KM <13>, IKA <112> and IKK <122> are divided from one another by a dividing wall W <16>, - in the cases in which the electrolysis cell E <1> comprises at least one middle chamber KM <13>, IKK <122> and IKM <132> are divided from one another by a dividing wall W <16>, wherein the dividing wall W <16> has one side SKK <161> having the surface OKK <163> and a side SA / MK <162> which is opposite the side SKK <161> and has the surface OA / MK <164>, wherein the dividing wall W <16> comprises at least one alkali metal cation-conducting solid-state electrolyte ceramic FA <18> in such a way that the alkali metal cation-conducting solid-state electrolyte ceramic FA <18> encompassed by the dividing wall W <16> makes direct contact with the interior IKK <122> on the side SKK <161> via the surface OKK <163>, and wherein - in the cases in which the electrolysis cell E <1> does not comprise a middle chamber KM <13>, the alkali metal cation-conducting solid-state electrolyte ceramic FA <18> encompassed by the dividing wall W <16> makes direct contact with the interior IKA <112> on the side SA / MK <162> via the surface OA / MK <164>, - in the cases in which the electrolysis cell E <1> comprises at least one middle chamber KM <13>, the alkali metal cation-conducting solid-state electrolyte ceramic FA <18> encompassed by the dividing wall W <16> makes direct contact with the interior IKM <132> on the side SA / MK <162> via the surface OA / MK <164>, (α) wherein, in the electrolysis cell E <1>, when it does not comprise a middle chamber KM <13>, the following steps (α1), (α2), (α3) that proceed simultaneously are performed: (α1) a solution L2 <22> comprising glycol is directed through IKK <122>, (α2) a neutral or alkaline, aqueous solution L3 <23> of a salt S comprising MA as cation is directed through IKA <112>, (α3) voltage is applied between EA <113> and EK <123>, or (β) wherein, in the electrolysis cell E <1>, when it comprises at least one middle chamber KM <13>, the following steps (β1), (β2), (β3) that proceed simultaneously are performed: (β1) a solution L2 <22> comprising glycol is directed through IKK <122>, (β2) a neutral or alkaline, aqueous solution L3 <23> of a salt S comprising MA as cation is directed through IKM <132>, then through VAM <15>, then through IKA <112>, (β3) voltage is applied between EA <113> and EK <123>, which affords the solution L1 <21> at the outlet AKK <121>, the concentration of MA glycolate being higher in L1 <21> than in L2 <22>, and which affords an aqueous solution L4 <24> of S at the outlet AKA <111>, the concentration of S being lower in L4 <24> than in L3 <23>; (b) reacting the solution L1 <21> with PET to give a mixture M1 comprising bis-2-hydroxyethyl terephthalate BHET.

2. Method according to Claim 1, wherein the alkali metal cation-conducting solid-state electrolyte ceramic FA <18> has a structure of the formula MI1+2w+x-y+z MIIw MIIIx ZrIV2-w-x-y MVy (SiO4)z (PO4)3-z, where MI is selected from Na+ and Li+, MII is a divalent metal cation, MIII is a trivalent metal cation, MV is a pentavalent metal cation, the Roman indices I, II, III, IV, V indicate the oxidation numbers in which the respective metal cations exist, and w, x, y, z are real numbers, where 0 ≤ x < 2, 0 ≤ y < 2, 0 ≤ w < 2, 0 ≤ z < 3, and where w, x, y, z are chosen such that 1 + 2w + x - y + z ≥ 0 and 2 - w - x - y ≥ 0.

3. Method according to Claim 1 or 2, wherein the electrolysis cell E <1> does not comprise a middle chamber KM <13>.

4. Method according to Claim 1 or 2, wherein the electrolysis cell E <1> comprises at least one middle chamber KM <13>.

5. Method according to any of Claims 1 to 4, wherein MA is selected from the group consisting of potassium, sodium.

6. Method according to any of Claims 1 to 5, wherein step (b) is conducted until at least P = 10% of the PET used in step (b) has been converted.

7. Method according to any of Claims 1 to 6, wherein step (b) is performed at the boiling temperature of the glycol.

8. Method according to any of Claims 1 to 7, wherein a sufficient amount of solution L1 <21> is used in step (b) that the total weight of the MA glycolate used in step (b), based on the total weight of the PET used in step (b), is in the range from 0.1% to 100% by weight.

9. Method according to any of Claims 1 to 8, wherein BHET is at least partly separated from M1 in a further step (c).

10. Method according to Claim 9, wherein the at least partial separation of BHET from M1 in step (c) is effected by crystallization and / or distillation.

11. Method according to any of Claims 1 to 10, wherein the PET is subjected to at least one pretreatment step selected from chemical pretreatment step, comminution step, before being used in step (b).

12. Method of recycling polyethylene terephthalate, in which BHET is obtained by a method according to any of Claims 1 to 11 and the BHET thus obtained is polymerized to PET in a step (ζ).

13. Method according to Claim 12, wherein the polymerization of BHET to PET in step (ζ) is conducted at at least the boiling temperature of the glycol.

14. Method according to Claim 12 or 13, wherein the polymerization in step (ζ) is performed in the presence of a catalyst.

15. Method according to Claim 14, wherein the catalyst is selected from the group consisting of antimony compounds.