Electrolysis cell for electrosynthesis of organic or organometallic compounds

Abstract

The present invention relates to an electrolysis cell for electrosynthesis of organic or organometallic compounds, comprising a sacrificial electrode having an active surface, and an unsacrificial electrode, having an active surface. The active surface of the unsacrificial electrode has a shape adapted to receive the sacrificial electrode such that the active surface of the sacrificial electrode faces the active surface of the unsacrificial electrode. The electrolysis cell comprises an inlet and an outlet for an electrolytic solution and a positioning element in the form of a pin configured to position the active surfaces to form an interelectrode gap, said interelectrode gap allowing the passage of the electrolytic solution. The sacrificial electrode movably rests on an upper support surface of the pin and the active surfaces of both electrodes have a shape and dimension such that the distance between the active surfaces is substantially constant along the interelectrode gap.

Description

Electrolysis cell for electrosynthesis of organic or organometallic compoundsField of the invention

[0001] The present invention relates to an electrolysis cell for electrosynthesis of organic or organometallic compounds and to a process for the electrosynthesis of organic or organometallic compounds.Description of the background art

[0002] Electrolysis is a technique wherein a direct current is used to drive chemical reactions. An electrolysis cell is the reactor in which electrolysis can take place. The cell typically comprises an external power source, two electrodes: anode and cathode, and an electrolytic solution (or electrolyte), containing free ions to allow carrying an electric current.

[0003] The electrodes are separated by a distance such that a current flows between them through the electrolytic solution. The potential that is reached between the two electrodes depends on i.a. the distance between the two electrodes and the composition of the electrolytic solution. The potential required for a reaction is characteristic for a certain chemical reaction. The direct current causes ions in the electrolyte to be attracted towards the respective oppositely charged electrode. Chemical reactions typically take place at the surface of the electrodes.

[0004] Electrolysis cells comprising a sacrificial electrode are known in the art. In these cells, at least one of the two electrodes is sacrificed during the electrosynthesis by the electrochemical reaction of which it forms the seat.

[0005] US 2019 / 0161871 describes an electrolytic reactor for the electrolytic recovery of phosphorus as a crystallized magnesium ammonium phosphate from phosphate-containing liquids by ionizing the surface of the sacrificial magnesium anode.

[0006] A disadvantage of using sacrificial electrodes is that the distance between the two electrodes changes as the surface of the sacrificial electrode is ionized. A change in interelectrode distance influences the reaction potential, thereby resulting in sub-optimum results of the electrosynthesis.

[0007] Another disadvantage of using sacrificial electrodes is the fact that the cells require frequent renewal of the sacrificial electrode. This is inconvenient as this typically requires the reaction to be stopped and the cell to be opened.

[0008] US46860187 describes an electrolysis cell for the electrosynthesis, in an organic medium, of organic or organometallic compounds comprising an unsacrificial electrode and a sacrificial electrode, wherein the sacrificial electrode is applied under the influence of its own weight against the unsacrificial electrode. An electrical insulating spacer in the form of a plastic grid comprising two parallel superimposed wire networks is placed in between the two electrodes to separate them and to allow passage of the electrolytic organic solution.

[0009] A disadvantage of the cell described in US46860187 is that the minimum interelectrode gap is limited by the thickness of the plastic spacer.

[0010] Another disadvantage of the cell described in US46860187 is that the erosion of the sacrificial electrode can be uneven since the grid of the plastic spacer is a physical barrier sitting between the electrodes. Uneven erosion leads to variance in the distance between the electrodes and could lead to cell potential changes over time.

[0011] Furthermore, another disadvantage of a polymeric spacer is that it partially blocks active surface of the unsacrificial electrode, thereby blocking active sites at which an electrochemicalreaction could occur.

[0012] Another disadvantage of using a polymeric spacer as described in US46860187 is that in case a solid product is formed, the spacer may cause the product to hold up in dead zones, leading to blockage of the interelectrode gap.

[0013] Another disadvantage of the cell as described in US46860187 is that the use of a plastic spacer may limit the choice of electrolyte mediums, since the spacer material should be stable in the employed medium.

[0014] Thus, there is a desire for an electrolysis cell that does not have, or has to a lesser extent, one or more of the abovementioned disadvantages.

[0015] In particular there is a desire for an electrolysis cell comprising a sacrificial electrode that can run with increased duration while substantially maintaining a stable potential over time.

[0016] Furthermore there is a desire for an electrolysis cell that can be used for the production of organic or organometallic compounds that are insoluble in the electrolyte medium.Summary of the invention

[0017] It has now been found that this may be achieved, at least in part with the electrolysis cell for the electrosynthesis of organic or organometallic compounds according to the present invention.

[0018] Thus, the present invention relates to an electrolysis cell for electrosynthesis of organic or organometallic compounds, comprising a sacrificial electrode, comprising at least one block of conductive material, wherein the sacrificial electrode has an active surface; an unsacrificial electrode, having an active surface, wherein the active surface of the unsacrificial electrode has a shape adapted to receive the sacrificial electrode such that the active surface of the sacrificial electrode faces the active surface of the unsacrificial electrode; an inlet and an outlet for an electrolytic solution; a positioning element configured to position the active surfaces of the sacrificial electrode and the unsacrificial electrode relative to each other to form an interelectrode gap, said interelectrode gap allowing passage of electrolytic solution; wherein the positioning element is a pin; wherein the pin comprises an upper support surface which is adapted to moveably support the sacrificial electrode; and wherein the active surfaces of both electrodes have a shape and dimension such that the distance between the active surfaces is substantially constant along the interelectrode gap.

[0019] Optionally, the electrolysis cell further comprises a housing, in which for example both the sacrificial electrode and the unsacrificial electrode are arranged. The electrolysis cell further preferably comprises a guiding element for keeping the sacrificial electrode in place. The guiding element may be in the form of one or more stabilizing rods or pins at the top of the electrolysis cell, preferably placed outside of the interelectrode gap. The guiding element may also be in the form of a cage placed outside of the interelectrode gap around the sacrificial electrode. The guiding element is preferably made of a non-conductive material or may be coated with a non- conductive material. The guiding element may be attached or fastened to the housing. Optionally, the guiding element allows for tilting the sacrificial electrode and / or for sideways movement of the sacrificial electrode, for example in order to allow centering (e.g. self-centering) and / oralignment (e.g. self-alignment) of the sacrificial electrode. To this end, for example a clearance is present between the guiding element and the sacrificial electrode.

[0020] The active surface of the sacrificial electrode is the area of the material of the sacrificial electrode that during use of the electrolysis cell is accessible to the electrolytic solution. Likewise, the active surface of the unsacrificial electrode is the area of the material of the unsacrificial electrode that during use of the electrolysis cell is accessible to the electrolytic solution. The active surface of the sacrificial electrode may have a shape which is tapered, e.g. a conical, pyramidal or dihedral shape with the respective apex or edge pointing downwards, with the active surface of the sacrificial electrode having a constant inclination relative to the central axis of the conical, pyramidal or dihedral shape. Preferably, the active surface of the sacrificial electrode has a pyramidal or conical shape. More preferably, the active surface of the sacrificial electrode has a conical shape.

[0021] The constant inclination of the active surface of the sacrificial electrode is preferably equal to or more than 5 degrees, preferably equal to or more than 7 degrees relative to the central axis. A too small angle might lead to a fragile sacrificial electrode with a risk of the sacrificial electrode being eroded or sacrificed too fast resulting in breaking of the sacrificial electrode.

[0022] The constant inclination of the active surface of the sacrificial electrode is preferably equal to or less than 45 degrees, preferably equal to or less than 35 degrees relative to the central axis. A larger angle means that the sacrificial electrode will be wider. A too large angle may lead to an uneven flow of the electrolytic solution in the interelectrode gap, which may result in accumulation of products or reactants in the interelectrode gap. Wider sacrificial electrodes typically need higher flows for the electrolytic solution.

[0023] The sacrificial electrode rests on top of the positioning element in a moveable manner, i.e. the positioning element supports the sacrificial electrode while still allowing movement of the sacrificial electrode relative to the positioning element. The positioning element positions the active surfaces of the sacrificial electrode and the unsacrificial electrode relative to each other to form an interelectrode gap. By this positioning, the positioning element may separate the active surfaces of the sacrificial electrode and the unsacrificial electrode to form an interelectrode gap, so the positioning element may function as a separating element.

[0024] In accordance with the invention, the positioning element (i.e. the separating element) is a pin. The pin has an upper support surface on top of which the sacrificial electrode rests in a movable manner. In other words, the upper support surface of the pin is adapted to moveably support the sacrificial electrode. The upper support surface is for example the upper surface of the pin. The upper support surface is adapted to moveably support the sacrificial electrode, i.e. the sacrificial electrode is moveable relative to the upper support surface. For example, the sacrificial electrode is tiltable relative to the upper support surface of the pin, and / or for example when the part of the sacrificial electrode that initially (i.e. at the start of the reaction) engages the upper support surface gets consumed by the reaction, the sacrificial electrode as a whole moves downward towards the upper support surface of the pin. This inherent downward movement during an electrochemical reaction, allows for an extended reaction time without having to reset the electrolytic cell in order to reposition the sacrificial electrode relative to the unsacrificial electrode.

[0025] The upper support surface of the pin may be flat, but preferably the upper support surface of the pin has a shape adapted to receive the sacrificial electrode. For example, the upper supportsurface of the pin may comprise an indent or a groove. Such an indent or groove has the advantage of centering and / or stabilizing the sacrificial electrode and keeping it in place.

[0026] Depending on the shape of the active surface of the sacrificial electrode, the sacrificial electrode may end in an apex (conical or pyramidal shape) or in an edge (dihedral shape). Accordingly, the upper support surface of the pin may therefore comprise an inverse conical, pyramidal or dihedral shape to receive the sacrificial electrode.

[0027] In the electrolysis cell according to the invention, it is not necessary to adjust the position of the positioning element in order to keep the reaction going, as the part of the sacrificial electrode that engages the positioning element is consumed by the reaction as well. This way, the sacrificial electrode moves towards the positioning element during the reaction and the distance between the active surfaces remains substantially constant along the interelectrode gap during the reaction, even if the reaction takes place during a substantial period of time. So, the positioning element does not have be re-adjusted to keep the reaction going. However, in a preferred embodiment according to the invention, the pin is movable to allow adjusting the distance between the active surfaces of the electrodes in the interelectrode gap, for example to set up the electrolysis cell for a different kind of reaction. Preferably, the interelectrode gap can be adjusted to achieve a predetermined distance and / or a predetermined voltage between the electrodes. This advantageously allows the use of the electrolysis cell for different electrochemical reactions. In some embodiments, the pin is movable when preparing the cell before reaction. In other embodiments, the pin is also movable during the electrochemical reaction, for example in order to control the reaction speed, or to interrupt or start or re-start the reaction. An advantage of this is that the distance between the active surfaces of the electrodes can be adjusted during reaction, hence also the potential between the electrodes can be adjusted during reaction.

[0028] In some embodiments, the moving of the pin is achieved via the manual adjustment of the position of the pin. In a preferred embodiment, the adjustment of the distance between the active surfaces of the electrodes is automated and is controlled based on a measured potential between the electrodes.

[0029] Generally, the distance between the active surfaces of the electrodes in the interelectrode gap may be between 0.5 and 15 mm. In a preferred embodiment, the distance is between 0.5 and 10 mm, preferably between 0.5 and 5 mm, even more preferably between 0.8 and 3 mm.

[0030] The electrolysis cell according to the invention comprises an inlet for an electrolytic solution and an outlet for the electrolytic solution. An electrolyte channel extends between at least one inlet and at least one outlet. If there are multiple inlets and / or multiple outlets, a single electrolyte channel extends between all inlets and all outlets, or alternatively, multiple electrolyte channels are provided, each electrolyte channel extending between at least one inlet and at least one outlet. At least a part of the electrolyte channel is delimited by at least a part of the active surface of the sacrificial anode and at least a part of the active surface of the unsacrificial anode. The electrolyte channel contains at least a part of the interelectrode gap. The inlet of the electrolysis cell for the electrolytic solution is preferably placed at the bottom of the electrolysis cell. As such, the electrolysis cell is configured to allow electrolytic solution to enter the interelectrode gap at the bottom and to flow through the interelectrode gap to the outlet, which is preferably placed at the top of the interelectrode gap or may be placed above the interelectrode gap. Alternatively, the inlet of the electrolysis cell for the electrolytic solution may be placed at the top of the interelectrode gap or may be placed above the interelectrode gap. As such, the electrolysis cell is configured to allow electrolytic solution to enter the interelectrode gap at thetop and to flow through the interelectrode gap to the outlet which, in this case, may be placed at the bottom of the electrolysis cell or at the bottom of the interelectrode gap.

[0031] The electrolysis cell according to the invention may comprise more than one inlet. The electrolysis cell may comprise two, three, four, or more inlets. This advantageously allows the electrolysis reaction to continue even in the case wherein an inlet is blocked by, for example, formed organic or organometallic compounds or accumulated reactants or salts.

[0032] The electrolysis cell allows for electrolytic solution to enter the electrolysis cell in the interelectrode gap via the one or more inlets and to exit the cell via the one or more outlets. The electrolytic solution transports reactants and products of the reaction of which the electrolysis cell forms the seat. The electrolysis cell may be adapted to introduce electrolytic solution with a flow rate between 50 kg / (h-m2) and 2050 kg / (h-m2), preferably between 100 kg / (h-m2) and 1000 kg / (h-m2). The flow rate is defined as the flow per m2active surface of the electrodes. A too low flow rate has the disadvantage of the buildup of reaction products leading to blockage of the interelectrode gap. A too high flow rate might lead to a low conversion of reactants in the electrolysis cell. Furthermore, a too high flow rate may result in mechanical erosion of the electrodes which is undesirable.

[0033] The sacrificial electrode comprises of at least one block, e.g. a solid block, of conductive material. In a preferred embodiment, the sacrificial electrode consists of at least one block of conductive material. In another preferred embodiment, the sacrificial electrode consists of layers of stacked blocks, e.g. solid blocks, of conductive material, wherein preferably each layer contains a single block. The electrolysis cell according to the invention advantageously enables the sacrificial electrode to be replaced easily without stopping the electrolysis by superimposition of one or more solid blocks of conductive material which form the sacrificial electrode.

[0034] The electrodes may each comprise an electrical connection connected to an electrical power supply to allow an electrical current to be applied to the electrodes. The electrical current density that is applied is generally between 0.05 and 10 kA / m2, preferably between 0.05 and 5 kA / m2, more preferably between 0.5 and 2 kA / m2. A too low electrical current has the disadvantage of resulting in a low productivity. A too high electrical current may affect the selectivity of the reaction, depending on the reaction that takes place in the electrolysis cell.

[0035] Typically, the sacrificial electrode is an anodic electrode (anode) and the unsacrificial electrode is an cathodic electrode (cathode).

[0036] The electrolysis cell according to the invention preferably does not contain any further separating elements in the interelectrode gap. Preferably, the interelectrode gap is free from any flow inhibiting elements and / or flow obstructing elements. Minimal physical interference between the electrodes allows for maximum use of the active surfaces of the electrodes and limits the formation of blockages. The pin that is used for separating the electrodes (i.e. the positioning element) is arranged outside the interelectrode gap.

[0037] In another aspect, the invention relates to a process for electrosynthesis of organic or organometallic compounds, said process comprising the steps of introducing an electrolytic solution and one or more reactants into an electrolysis cell according to the invention; and applying a potential.

[0038] In a preferred process, the organic or organometallic compounds are insoluble in the electrolytic solution.

[0039] In a preferred embodiment of the process, the electrolytic solution is a non-aqueous solution.

[0040] In another aspect, the invention relates to the use of the electrolysis cell for the electrosynthesis of organic and / or organometallic compounds. In particular, the invention relates to the use of the electrolysis cell according to the invention for the electrosynthesis of organic and / or organometallic compounds that are insoluble in the electrolytic solution. The electrolysis cell according to the solution also allows for the electrosynthesis of organic and / or organometallic compounds using a non-aqueous electrolytic solution.Brief description of the drawings

[0041] The features and advantages of the invention will be appreciated upon reference to the following drawings, in which:

[0042] Figure I is a simplified schematic diagram of one embodiment according to the invention, showing a cross-section of an electrolysis cell.

[0043] Figure II shows the embodiment depicted in Figure I, zooming in on the sacrificial electrode movably resting on the upper support surface of the pin that forms the positioning element.

[0044] The drawings are intended for illustrative purposes only, and do not serve as restriction of the scope or the protection as specified in the claims.Detailed description of the invention

[0045] The following is a description of certain embodiments of the invention, given by way of example only and with reference to the drawings.

[0046] The electrolysis cell according to the invention optionally comprises a housing. The housing may be adapted for holding the electrodes and connections to the electrolysis cell and may provide stability to the electrolysis cell. The housing may be made of a non-conducting material. The electrolysis cell may also comprise an isolating layer between the housing and the electrodes.

[0047] The electrolysis cell comprises an unsacrificial electrode and a sacrificial electrode each of which comprise active surfaces which are separated from each other and therewith positioned relative to each other by a positioning element (i.e. separating element) in the form of a pin to form an interelectrode gap. One or more inlets allow for an electrolytic solution to enter the electrolysis cell, which flows through the interelectrode gap and exits the electrolysis cell via one or more outlets. The electrodes may be connected to an external power source via electrical connections.

[0048] Unsacrificial electrodes are known in the art and are electrodes comprising materials that do not degrade, hence are not sacrificed, under the conditions of the electrochemical reaction of which they form the seat. The unsacrificial electrode is capable of conducting an applied electrical current, but the conductive material is not ionized. The unsacrificial electrode according to the invention comprises an active surface. The active surface, having active sites, is formed by the part of the surface of the unsacrificial electrode that faces the interelectrode gap through which the electrolytic solution flows.

[0049] The active surface of the unsacrificial electrode may be made of a conducting unsacrificial material. Said material may be a metal or an alloy and may or may not be the same material as the unsacrificial electrode. The unsacrificial electrode may also be coated with a conductive material to obtain an active surface that is conductive. Examples of unsacrificial conductivematerials are indium, tin, lead, mercury, thallium, iron, nickel, chromium, molybdenum and niobium and alloys comprising one or more of the above.

[0050] The unsacrificial electrode may comprise an electrical connection to an external power source. This electrical connection may comprise copper wires.

[0051] The electrolysis cell further comprises a sacrificial electrode. Sacrificial electrodes are known in the art and are electrodes comprising materials which are sacrificed by the electrochemical reaction from which it forms the seat. Requirements for materials in sacrificial electrodes are high conductivity and a high oxidation potential. Examples are metals such as zinc, aluminum, magnesium, iron, and alloys comprising one or more of the above. Pure metals are often preferred over alloys, because the use of alloys in electrochemical syntheses may lead to a mix of products with different cations or uneven erosion of the sacrificial electrode. Under the influence of an applied electrical current, the sacrificial materials degrade or are ionized. The sacrificial electrode according to the invention preferably consists substantially of sacrificial materials and comprises an active surface. The sacrificial electrode according to the invention preferably consists at least 95 wt.% of sacrificial materials, preferable at least 98 wt.%, more preferably at least 99 wt.%, even more preferably at least 99.9 wt.% and most preferably 100 wt.% of sacrificial materials.

[0052] The active surface, having active sites, of the sacrificial electrode is formed by the part of the surface of the sacrificial electrode that faces the interelectrode gap through which the electrolytic solution flows. The active surface of the sacrificial electrode is consumed (sacrificed) during the electrochemical reaction, thereby exposing the material underneath, which replaces the consumed (sacrificed) material and forms the new active surface. As such, under electrolysis conditions, the active surface of the sacrificial electrode is continuously replaced.

[0053] The electrolytic solution enters the electrolysis cell via the inlet and flows through the interelectrode gap towards the outlet. The electrolysis cell according to the invention may comprise more than one inlet, such as two inlets, but the cell may comprise at least three, or at least four inlets. This advantageously allows the electrolysis reaction to continue even in the case wherein an inlet is blocked by, for example, formed organic or organometallic compounds. Furthermore, it allows for a more even distribution of the electrolytic solution around the sacrificial electrode.

[0054] The electrolysis cell according to the invention may also comprise more than one outlet. The electrolysis cell may comprise two, three, four, or more outlets. In an embodiment according to the invention, the one or more outlets are situated at the top of the interelectrode gap, at the position where the sacrificial electrode is at its widest. Multiple outlets, preferably located at different positions around the sacrificial electrode, allow for the electrolytic solution to exit the electrolysis cell without having to flow around the sacrificial electrode to reach the exit. This prevents excessive mechanical erosion of the sacrificial electrode.

[0055] The one or more outlets are adapted for the exit of the electrolytic solution, which may comprise unreacted reactants or products that are formed under electrolysis conditions. The one or more outlets may also be adapted for the exit of gaseous components and / or solid components. The electrolysis cell may also comprise an additional outlet for gaseous components.

[0056] The electrolytic solution may be an aqueous or non-aqueous solution and allows for the conduction of the electric current that is applied to the electrodes of the electrolysis cell. Nonlimiting examples of electrolytic solutions comprise solvents such as acetonitrile, dimethylformamide, dimethyl sulfoxide, propene carbonate, methanol and tetrahydrofuran andcomprise salts such as Li+or Na+electrolytes (for example LiCIO4or Nal) or tetraalkylammonium electrolytes having, for example, Me4N*, Et4N* or Bu4N* as supporting cations and, for example, BF4‘, CIO4‘, PFg" as supporting anions.

[0057] The electrolytic solution may comprise reactants that can be electrochemically converted to the desired organic or organometallic products. Reactants for the electrolysis reaction may also enter the electrolysis cell and in particular the interelectrode gap via a separate reactant inlet. This reactant inlet may be adapted for introducing gaseous or liquid or dissolved components into the electrolysis cell.

[0058] The electrolytic solution may enter the electrolysis cell with a flow rate of between 50 kg / (h-m2) and 2050 kg / (h-m2), preferably of between 100 kg / (h-m2) and 1000 kg / (h-m2). The flow rate is defined as the flow per m2active surface of the electrodes. The flow may be achieved using a pump. The flow preferably is not too high, since this would lead to erosion of the sacrificial electrode. The consumption of the sacrificial electrode preferably only takes place under the influence of the electrochemical reaction taking place and not under the influence of the flow of the electrolytic solution via so-called mechanical erosion. In the former, the sacrificial materials are ionized and thus function as active sites for the electrolysis reaction. In the latter, the sacrificial materials are not used as active sites. Instead the sacrificial material ends up in the product flow as a waste product. The flow is preferably also not too low, since this results in a lower electrochemical activity and might lead to blockage of optional solid reaction products.

[0059] The flow rate of the electrolytic solution may also influence the residence time of reactants and products during the electrosynthesis. The residence time is the duration for which molecules are present in the interelectrode gap and may thus react. A too high flow rate may thus also lead to lower electrochemical activity, because the residence time for reactants is too low. A too low flow rate might lead to products staying too long in the interelectrode gap with the risk of further reacting to undesired products, because the residence time for reactants and / or products is too high.

[0060] The flow rate may also be (co-)determined by the dissolution rate of reactants. If a flow rate is too high, reactants may not have had enough time to fully dissolve in the electrolytic solution. This may result in a lower conversion rate of reactants.

[0061] Typically, the sacrificial electrode is the anode in the electrolysis reaction and the unsacrificial electrode is the cathode. The electrolysis cell according to the invention also includes embodiments wherein the cathode is a sacrificial electrode and the anode is the unsacrificial electrode.

[0062] A positioning element in the form of a pin is configured to separate the active surfaces of the sacrificial electrode and the unsacrificial electrode from each other (i.e. to position the active surfaces of the sacrificial electrode and the unsacrificial electrode relative to each other) to form an interelectrode gap, said interelectrode gap allowing passage of electrolytic solution. The pin separates the active surfaces of the two electrodes to prevent the touching of the electrodes which may lead to short circuit under electrolysis conditions.

[0063] The term pin may cover embodiments such as, for example, a rod, ingot, stick or small cylinder which may function as a positioning element on top of which the sacrificial electrode may rest.

[0064] The pin may be attached or connected or fastened to the housing of the electrolysis cell and / or may be connected or fastened or attached to the unsacrificial electrode.

[0065] The pin may be positioned in line with the central axis of the sacrificial electrode and the sacrificial electrode is movably supported by an upper support surface of the pin. The sacrificial electrode may rest on the upper support surface of the pin under the influence of its own weight. In some embodiments, the sacrificial electrode rests on the upper support surface of the pin under the sole influence of its own weight. In other embodiments, the sacrificial electrode rests on the upper support surface of the pin under the influence of, in addition to that of its own weight, an inert load resting on the sacrificial electrode and / or of a force produced by a spring which is compressed between the upper part of the sacrificial electrode and one side of the electrolysis cell.

[0066] The upper support surface of the pin may be flat, but preferably the upper support surface of the pin has a shape adapted to receive the sacrificial electrode. For example, the upper support surface of the pin may comprise an indent or a groove in which the sacrificial electrode may rest. Such an indent has the advantage of centering and / or stabilizing the sacrificial electrode and keeping it in place.

[0067] The indent or groove may have a depth of between 0.5 and 100 mm, preferably between 0.8 and 50 mm, more preferably between 1 and 30 mm. A too shallow indent will lead to undesired lateral movement of the sacrificial electrode, whereas a too deep indent might lead to uneven erosion at the bottom of the sacrificial electrode. The depth of the indent may vary depending on the dimensions of the cell.

[0068] Any indent shape aids to a certain extent in the centering and / or stabilizing of the sacrificial electrode. In a preferred embodiment, however, the indent has a shape resembling the inverted shape of the sacrificial electrode. This means that in the case where the active surface of the sacrificial electrode has a conical shape, the indent has a reverse conical shape. In the case where the sacrificial electrode has a pyramidal shape, the indent has a reverse pyramidal shape and in the case wherein the sacrificial electrode has a dihedral shape, the indent has a groove (reverse edge). In some embodiments, the sacrificial electrodes have rounded apexes or edges and the upper support surfaces of the pins may comprise shapes having curved indents resembling the inverted shapes of the rounded apexes or edges of the sacrificial electrode. An indent having the inverted shape of the sacrificial electrode allows for optimized stabilization and centering of the sacrificial electrode.

[0069] The upper support surface of the pin may therefore comprise an inverse conical, pyramidal or dihedral shape to receive the sacrificial electrode.

[0070] In a preferred embodiment, the shape of the sacrificial electrode has a rounded apex or edge. For example, when the active surface of the sacrificial electrode has a conical shape with a rounded apex at the bottom which rests on the upper support surface of the pin. It is then preferred that the upper support surface of the pin has a shape to receive this rounded apex, preferably a shape resembling an inverted conical shape with a rounded apex.

[0071] It is preferred that charge transport around the apex of the sacrificial electrode is not hindered or obstructed by the upper support surface of the pin. This may be the case when the upper support surface of the pin has an indent in which the sacrificial electrode rests and wherein the indent isolates the tip of the sacrificial electrode. Due to the isolation, the electrolytic solution cannot reach this part of the sacrificial electrode, leading to uneven consumption of the sacrificial electrode. Improving the charge transport around the tip of the sacrificial electrode may be established, for example, by additional grooves or indents around the indent on the pin. However, such measures will not always be necessary. It has been observed that in some cases the chargetransport from the side areas of the sacrificial electrode adjacent to the apex is sufficient to also consume the apex of the sacrificial electrode.

[0072] The indent advantageously allows the sacrificial electrode to stay centred in the electrolysis cell and it prevents the sacrificial electrode from undesired moving, thereby maintaining a substantially stable interelectrode distance. With the active surfaces of the electrodes facing each other in a substantially parallel way and the interelectrode distance being substantially constant, i.e. substantially similar, along the interelectrode gap, this results in a more even consumption of the active surface of the sacrificial electrode. A substantially constant distance means that the interelectrode distance is substantially similar. Once the sacrificial electrode moves from its centred position, the interelectrode distance would become uneven, leading to a variance in potential over the interelectrode gap. Not only could this lead to different reaction products being formed during electrolysis but it also may lead to an uneven consumption of the sacrificial electrode and / or a deformation of the shape of the active surface. In case this would happen, the electrolysis would have to be stopped regularly to open the cell and replace the entire sacrificial electrode.

[0073] The interelectrode distance in the electrolysis cell according to the invention is substantially constant along the interelectrode gap meaning a maximum variance of 30% based on the highest value, which means the largest distance between the active surfaces of the electrodes along the interelectrode gap, preferably a maximum variance of 20%, more preferably a maximum variance of 10%, more preferably a maximum variance of 5%, even more preferably a maximum variance of 2%.

[0074] Similarly, under electrolysis conditions, the interelectrode distance in the electrolysis cell according to the invention is substantially constant along the interelectrode gap to achieve a substantially constant, i.e. substantially similar, potential, meaning a maximum variance of 30% of the largest potential along the interelectrode gap, preferably a maximum variance of 20%, more preferably a maximum variance of 10%, more preferably a maximum variance of 5%, even more preferably a maximum variance of 2%.

[0075] The pin preferably has a non-conductive surface to prevent an applied electrical current to run through the pin resulting in short-circuit during electrolysis. The non-conductive surface of the pin also prevents the erosion or consumption of the pin during electrolysis. This can be achieved, for example, by pins made from polymeric or ceramic materials or by coating a pin with a non-conductive coating. In one embodiment, the pin is a metallic pin that is coated with a non- conductive coating. A metallic pin is stronger to carry the weight of the sacrificial electrode and is more rigid and robust compared to polymeric pins. In another embodiment, the pin is made of a polymeric or ceramic material and may be supported by a supporting screw. The supporting screw is isolated from the electrodes and electrolytic solution by the non-conductive pin.

[0076] The electrolysis cell may further comprise a guiding element. The guiding element together with the positioning element may allow for the sacrificial electrode to stay in place. The guiding element may be in the form of one or more stabilizing (non-conductive) rods or pins at the top of the electrolysis cell, preferably placed outside of the interelectrode gap. The guiding element may also be in the form of a (non-conducting) cage placed outside of the interelectrode gap around the sacrificial electrode. The guiding element is preferably made of a non-conductive material or may be coated with a non-conductive material. The one or more guiding elements may be attached or fastened to the housing.

[0077] The indent or groove on top of the pin may be combined with one or more guiding elements to aid a stabilized position of the sacrificial electrode. It also limits variation in the distance between the active surfaces, thereby allowing a more stable voltage during electrolysis. Optionally, the guiding element allows for tilting the sacrificial electrode and / or for sideways movement of the sacrificial electrode, for example in order to allow centering (e.g. self-centering) and / or alignment (e.g. self-alignment) of the sacrificial electrode. To this end, for example a clearance is present between the guiding element and the sacrificial electrode.

[0078] The electrolysis cell according to the invention makes use of the pin as a positioning element. By placing the pin outside of the interelectrode gap, along the central axis of the sacrificial electrode and letting the sacrificial electrode rest on the upper support surface of the pin, it eliminates the need for any other physical barriers, for example polymeric spacers, grids, cloth, linen or ceramic spacers, in the interelectrode gap to maintain an interelectrode distance and corresponding potential. This has several advantages.

[0079] First, physical barriers lead to uneven corrosion of the sacrificial electrode, leading to potential changes over time. The electrolysis cell according to the invention allows for more even corrosion or consumption of the sacrificial electrode, thereby better maintaining the shape of the active surface.

[0080] Second, physical barriers in the interelectrode gap may block active sites on either active surface, thereby reducing electrochemical activity. The electrolysis cell according to the invention optimizes the active surface area of the electrodes by minimal blockage of the active sites on the electrodes.

[0081] Third, in case of a reaction where a solid product is formed, the presence of physical barriers in the interelectrode gap may cause the product to hold up in dead zones resulting in blockage of the interelectrode gap. The electrolysis cell according to the invention is particularly suitable for the electrochemical production of solid organic or organometallic products, in other words products that are insoluble in the electrolytic solution. The electrolytic solution carries the product formed at the active sites of the active surface of the electrodes and flows towards the outlet.

[0082] The pin separates the active surfaces of the electrodes in the electrolysis cell, thereby creating a distance between the electrodes. The desired distance between the electrodes is different depending on the choice of reaction that takes place in the cell. Some reactions require large distances, for instance to allow solid product to be formed and to be transported towards the outlet without blockage of the interelectrode gap. The distance between the electrodes also determines the applied potential or voltage at a given current. Depending on the nature of the electrochemical reaction, the material of the electrodes and the required productivity and selectivity, different interelectrode distances may be required.

[0083] In an advantageous embodiment according to the invention, the pin is movable relative to the unsacrificial electrode and / or to the housing (if present) to allow adjusting the distance between the active surfaces of the electrodes. This preferably is achieved by using a pin that comprises threading allowing movement through rotation. Finer threading allows for finetuning the interelectrode distance. In another embodiment, the pin is supported by a supporting screw, which allows for movement through rotation. The pin and / or supporting screw may be fastened to the housing of the electrolysis cell and / or to the unsacrificial electrode and the position may be adjusted to achieve a predetermined distance between the active surfaces of the electrodes.

[0084] In a preferred embodiment according to the invention, the pin is adapted to adjust the interelectrode gap to achieve a predetermined distance and / or a predetermined potential. This may be achieved, for instance, by applying a current to the electrodes and measuring the potential over the electrodes using a sensor while adjusting the position of the pin until a desired potential is achieved.

[0085] In a preferred embodiment, the position of the pin is adjustable during electrolysis. This may advantageously allow for control of the reaction speed. For example, a reaction can be simply stopped by moving the pin to create a too large distance for the reaction to take place.

[0086] The interelectrode distance that is achievable in the electrolysis cell according to the invention may vary depending on the dimension of the electrolysis cell and the dimensions of the pin. For example, a long pin may allow for large interelectrode distances, while a shorter pin allows for smaller interelectrode distances.

[0087] In general, the electrolysis cell according to the invention may allow for an interelectrode distance between 0.5 and 15 mm. In a preferred embodiment, the distance is between 0.5 and 10 mm, preferably between 0.5 and 5 mm, even more preferably between 0.8 and 3 mm. A too small distance between the electrodes might lead to blockage of the interelectrode gap, while a too large distance between the electrodes requires high potentials and / or high applied currents.

[0088] In one embodiment, the pin may form the inlet of the electrolysis cell for the electrolytic solution. The pin may comprise a partially hollow part through which the electrolytic solution can flow. The electrolytic solution enters the electrolysis cell via the openings in the pin. The electrolytic solution may enter the electrolysis cell via two or more openings, at least three, or at least four openings. More openings advantageously allow the flow of the electrolytic solution to continue when one opening is blocked. Furthermore, it allows for an even distribution of the electrolytic solution around the sacrificial electrode.

[0089] The sacrificial electrode comprises at least one block, preferably a solid block, of conductive material and comprises an active surface. In a preferred embodiment, the sacrificial electrode consists of at least one block, e.g. solid block, of conductive material and preferably comprises no non-conductive materials. Herein, solid block refers to a block of material that has a low porosity and is preferably non-porous. The active surface of sacrificial electrode is shaped prior to assembly of the cell to have a shape preferably chosen from a conical shape, a pyramidal shape or a dihedral shape with the respective apex or edge pointing downwards and resting on the upper support surface of the pin. The sacrificial electrode further extends upwards from the base of the shape as a prism, such as, for example, a triangular prism, square prism, pentagonal prism, etc up to a cylinder, having a cross-section of, respectively, a triangle, square, pentagon, etc, up to a circle.

[0090] The sacrificial electrode may consist of several blocks, preferably solid blocks, of conductive material. The blocks which may be superimposed on the bottom block of sacrificial material preferably have the same cross-section as the bottom block such that they fit on top of each other. It is preferred to have only one block per layer to prevent the presence of empty space in between the blocks. Preferably the blocks, preferably solid blocks of conductive material are casting ingots that are interlocked on top of each other. The interlocking prevents the movement of the individual layers while the entire sacrificial electrode moves downward due to the consumption of the active surface.

[0091] The active surface of the unsacrificial electrode may have a shape that resembles the inverted shape of the sacrificial electrode. In other words, it is adapted to receive the sacrificial electrode such that the active surfaces of the respective electrodes face each other. Furthermore, the shapes and the dimensions of the active surfaces of the electrodes enable the active surfaces to be substantially parallel and the distance between the active surfaces to be substantially constant, i.e. substantially similar, along the interelectrode gap.

[0092] The active surface of the sacrificial electrode may have a shape comprising a (n-fold) rotational symmetry with respect to the central axis of the electrode. In case of a dihedral shape, the sacrificial electrode comprises a two-fold rotational symmetry (n=2). The sacrificial electrode comprises a three-fold rotational symmetry (n=3) in case of a pyramidal shape with a triangular base, comprises a four-fold rotational symmetry (n=4) in case the pyramidal shape has a square base, comprises a five-fold rotational symmetry in case the pyramidal shape has a pentagonal base, and so forth up to comprising an n-fold rotational symmetry in case the pyramidal shape has an n-sided base. In case the sacrificial electrode has a conical shape, it comprises an infinite rotational symmetry with respect to the central axis of the sacrificial electrode.

[0093] The apex or edge of the sacrificial electrode may be rounded to allow a more stabilized centred sacrificial electrode. This also advantageously results in less breakage of the sacrificial electrode at the bottom, thereby reducing the risk of fracturing the sacrificial electrode.

[0094] Sacrificial electrodes having an active surface having a shape comprising an apex, or rounded apex, pointing downwards, such as a pyramidal or conical shape, are preferred. These sacrificial electrodes are more evenly consumed, allowing for increased durations for electrolysis.

[0095] In a preferred embodiment, the sacrificial electrode has a cylindrical shape, having a circular cross-section, extending downwards to the active surface having a conical shape with an infinite rotational symmetry with respect to its central axis and an rounded apex of the cone pointing downwards and wherein said active surface has a constant inclination relative to the central axis. The rounded apex of the cone preferably rests on the upper support surface of the pin, the upper support surface having a shape resembling the inverse shape of the rounded apex of the sacrificial electrode to receive said sacrificial electrode.

[0096] When the active surface of sacrificial electrode has a conical shape, the active surface of the unsacrificial electrode preferably has a shape resembling the inverse shape of a cone having a similar inclination with respect to its central axis, such that the active surfaces are parallel along the interelectrode gap.

[0097] Their respective shapes allow the active surfaces to be substantially parallel to each other along the interelectrode gap. As the distance between the active surfaces of the electrodes is substantially constant, along the interelectrode gap, the potential at a given electrical current is substantially stable as well. This may result in an even consumption of the active surface of the sacrificial electrode, thereby maintaining its shape.

[0098] The electrolysis cell according to the invention advantageously enables the sacrificial electrode to be replaced easily without stopping the electrolysis by superimposition of one or moreblocks e.g. solid blocks, of conductive material which form the sacrificial electrode. Under electrolysis conditions, the active surface of the sacrificial electrode is consumed. As a result the whole sacrificial electrode slowly moves down, while the shape of the active surface is maintained. The superimposition of additional blocks of conductive material allows for the electrolysis reaction to continue with increased duration.

[0099] In a preferred embodiment according to the invention, the active surface has a constant inclination relative to the central axis. In a preferred embodiment, said inclination is equal to or more than 5 degrees relative to the central axis, more preferably equal to or more than 7 degrees relative to the central axis. Preferably, the active surface of the sacrificial electrode has an inclination equal to or less than 45 degrees relative to the central axis, preferably equal to or less than 35 degrees relative to the central axis.

[0100] When the inclination is too large, high flow rates are required to ensure that reaction products are flown out of the cell. Such high flow rates often result in non-uniform mechanical erosion of the electrodes.

[0101] When the inclination is too small, the sacrificial electrode material is consumed too fast to be replenished in time, leading to the collapse of the sacrificial electrode.[00102JA preferred embodiment of the sacrificial electrode according to the invention has an active surface area with a conical shape, wherein the active surface area has a constant inclination relative to the central axis such that the electrochemical consumption of the sacrificial electrode is uniform, maintaining the shape of the sacrificial electrode, while mechanical erosion is kept to a minimum.

[0103] The electrolysis cell according to the invention may be used for any electrosynthesis reaction that makes use of a sacrificial electrode. Examples of such electrosynthesis reactions are, but not limited to, carboxylation reactions, functionalization of alkenes and alkynes and carbonheteroatom bond formation reactions.

[0104] The invention thus also relates to a process for electrosynthesis of organic or organometallic compounds comprising the steps of a. introducing an electrolytic solution and one or more reactants into an electrolysis cell according to the invention; b. applying a potential.

[0105] In a preferred embodiment of the process, the organic or organometallic compounds are insoluble in the electrolytic solution and preferably the electrolytic solution is a non-aqueous solution.

[0106] The electrolysis cell according to the invention may in particular be used for non-aqueous reactions or for reactions that take place in undivided cells. An undivided cell is an electrolysis cell without a membrane that separates an anodic and cathodic reaction chamber.

[0107] The use of a sacrificial electrode may be advantageous in reactions wherein the consumption of the sacrificial electrode provides metal ions in the electrolytic solution that stabilizes intermediate products in the electrosynthesis.

[0108] The electrolysis cell according to the invention is in particular useful for carrying out electrosynthesis reactions in a continuous fashion while maintaining a stable potential.

[0109] The electrolysis cell according to the invention is also useful for the electrosynthesis of organic or organometallic compounds that are insoluble in the electrolytic solution.

[0110] During electrolysis, an electrical potential may be applied between the anode and the cathode sufficient for the desired reaction to take place and sufficient for the active surface of the sacrificial electrode to be ionized. The anode is positively charged and the cathode negatively. Inother words, an electrical potential may be applied to the electrochemical cell so that the anode is at a higher potential than the cathode.

[0111] It is noted that applying an electrical potential is considered synonymous with creating a voltage difference between the cathode and the anode, so that the anode is at a higher potential than the cathode. The process may be controlled by setting a certain voltage (potentiostatic) or by setting a certain current (galvanostatic). If the voltage is set, the current will automatically follow from the reactions that occur in the cell. If the current is set, the voltage will automatically follow from the reactions that occur in the cell. The process according to the invention is equally workable in both operation modes. Typically, the current is controlled in the start-up phase of an electrochemical cell, in order to find the optimal voltage for the desired reaction, while during standard operation of the electrochemical cell, the voltage will be controlled.

[0112] Preferably, the current density of the electrochemical cell during operation is at least 0.05 kA / m2, such as in the range of 0.05 and 10 kA / m2, preferably between 0.05 and 5 kA / m2, more preferably between 0.5 and 2 kA / m2. Herein, the currents are defined based on the projected area of the electrode. The optimal current for the process according to the invention may differ based on the exact conditions that are applicable in the electrolysis cell, and the skilled person is able to determine the optimal current in terms of product conversions.

[0113] Figure I is a simplified schematic diagram of one embodiment according to the invention, showing a cross-section of an electrolysis cell (1). The electrolysis cell (1) comprises a housing (2), two electrodes: a sacrificial anode (3) having an active surface (4) and a non-sacrificial cathode (5) having an active surface (6). The housing is separated from the conductive cathode (5) via isolating layer (15). The active surfaces of the two electrodes are separated by the positioning element (i.e. separating element) (10) in the form of a pin (10) to form the interelectrode gap (9) which allows passage of electrolytic solution. At the top of the interelectrode gap is a sealing layer (14) that prevents the electrolytic solution from flowing through other parts of the electrolysis cell (1). The electrolysis cell (1) allows for an electrolytic solution to enter the electrolysis cell (1) via inlets (8) and to exit the electrolysis cell (1) via outlets (7). The two electrodes have electrical connections (21 and 22) connected to an external electrical power supply (20). The sacrificial anode (3) rests on the upper support surface of the pin (10) and is further stabilized by non-conductive guiding elements (12) in the form of a non-conductive cage. The pin (10) comprises threading (11) which allows the movement of the pin (10) through rotation, allowing to adjust the distance between the two electrodes (3 and 5) and in particular the distance between their respective active surfaces (4 and 6) in the interelectrode gap (9). The active surface (4) of the sacrificial anode has a conical shape with the surface having a constant inclination a relative to the central axis which is indicated with the dash-point line. On top of the sacrificial anode (3) are casting ingots (13) which are cylinder shaped ingots made of the same conducting material as the sacrificial anode (3) and placed on top of the sacrificial anode (3) via interlocking pieces.

[0114] Figure II shows the same embodiment as depicted in Figure I, zooming in on the sacrificial electrode (3) resting on the upper support surface of the pin (10), thereby making that the sacrificial electrode is movably supported by the upper support surface of the pin. The sacrificial electrode (3) has a conical shape with a rounded apex (25) pointing downwards. The pin (10) has an upper support surface (26) comprising a curved indent (27), having the inverted shape of the rounded apex of the sacrificial electrode (3), in which the sacrificial electrode (3) moveably rests.

[0115] The following clauses furthermore describe embodiments according to the invention:CLAUSES1. Electrolysis cell for electrosynthesis of organic or organometallic compounds, comprising a housing; a sacrificial electrode, comprising at least one solid block of conductive material, wherein the sacrificial electrode has an active surface; an unsacrificial electrode, having an active surface, wherein the active surface of the unsacrificial electrode has a shape adapted to receive the sacrificial electrode such that the active surface of the sacrificial electrode faces the active surface of the unsacrificial electrode; an inlet and an outlet for an electrolytic solution; a separating element configured to separate the active surfaces of the sacrificial electrode and the unsacrificial electrode to form an interelectrode gap, said interelectrode gap allowing passage of electrolytic solution; characterized in that: the separating element is a pin; wherein the sacrificial electrode rests on top of the pin; and wherein the active surfaces of both electrodes have a shape and dimension such that the distance between the active surfaces is substantially similar along the interelectrode gap.2. The electrolysis cell according to clause 1, wherein the electrolysis cell further comprises a guiding element for keeping the sacrificial electrode in place.3. The electrolysis cell according to any of the preceding clauses, wherein the active surface of the sacrificial electrode has a conical, pyramidal, or dihedral shape, preferably a pyramidal or a conical shape, more preferably a conical shape, wherein said active surface has a constant inclination relative to the central axis of said conical, pyramidal or dihedral shape.4. The electrolysis cell according to clause 3, wherein the active surface of the sacrificial electrode has an inclination equal to or more than 5 degrees relative to the central axis, preferably equal to or more than 7 degrees relative to the central axis and wherein the active surface of the sacrificial electrode preferably has an inclination equal to or less than 45 degrees relative to the central axis, preferably equal to or less than 35 degrees relative to the central axis.5. The electrolysis cell according to any of the preceding clauses, wherein the pin comprises an upper surface having a shape adapted to receive the sacrificial electrode.6. The electrolysis cell according to any of the preceding clauses, wherein the pin is movable to allow adjusting the distance between the active surfaces of the electrodes in the interelectrode gap-7. The electrolysis cell according to clause 6, wherein the pin is adapted to adjust the interelectrode gap to achieve a predetermined distance between the active surfaces of the electrodes.8. The electrolysis cell according to clause 6 or 7, wherein the pin is adapted to adjust the interelectrode gap to achieve a predetermined voltage between the electrodes.9. The electrolysis cell according to any of the preceding clauses, wherein the distance between the active surfaces of the electrodes in the interelectrode gap is between 0.5 and 15 mm, preferably between 0.5 and 10 mm, more preferably between 0.5 and 5 mm, even more preferably between 0.8 and 3 mm.10. The electrolysis cell according to any of the preceding clauses, wherein the inlet is at the bottom of the electrolysis cell.11. The electrolysis cell according to any of the preceding clauses, wherein the electrolysis cell comprises at least two inlets.12. The electrolysis cell according to any of the preceding clauses, wherein the electrolysis cell is adapted for introducing an electrolytic solution with a flow rate between 50 and 2050 kg / (h-m2).13. The electrolysis cell according to any of the preceding clauses, wherein the sacrificial electrode consists of layers of stacked solid blocks of conductive material, each layer preferably containing only a single block.14. The electrolysis cell according to any of the preceding clauses, wherein the electrolysis cell does not contain any further separating elements in the interelectrode gap.15. Process for electrosynthesis of organic or organometallic compounds comprising the steps of a. introducing an electrolytic solution and one or more reactants into an electrolysis cell according to any of clauses 1-14; b. applying a potential. wherein the organic or organometallic compounds are preferably insoluble in the electrolytic solution and wherein the electrolytic solution is preferably a non-aqueous solution.

Claims

CLAIMS1. Electrolysis cell for electrosynthesis of organic or organometallic compounds, comprising a sacrificial electrode, comprising at least one block of conductive material, wherein the sacrificial electrode has an active surface; an unsacrificial electrode, having an active surface, wherein the active surface of the unsacrificial electrode has a shape adapted to receive the sacrificial electrode such that the active surface of the sacrificial electrode faces the active surface of the unsacrificial electrode; an inlet and an outlet for an electrolytic solution; a positioning element configured to position the active surfaces of the sacrificial electrode and the unsacrificial electrode relative to each other to form an interelectrode gap, said interelectrode gap allowing passage of electrolytic solution; characterized in that: the positioning element is a pin; wherein the pin comprises an upper support surface which is adapted to moveably support the sacrificial electrode; and wherein the active surfaces of both electrodes have a shape and dimension such that the distance between the active surfaces is substantially constant along the interelectrode gap.

2. The electrolysis cell according to claim 1, wherein the electrolysis cell further comprises a guiding element for keeping the sacrificial electrode in place.

3. The electrolysis cell according to any of the preceding claims, wherein the active surface of the sacrificial electrode has a tapered shape, preferably a conical, pyramidal, or dihedral shape, more preferably a pyramidal or a conical shape, even more preferably a conical shape, wherein said active surface has a constant inclination relative to the central axis of said conical, pyramidal or dihedral shape.

4. The electrolysis cell according to claim 3, wherein the active surface of the sacrificial electrode has an inclination equal to or more than 5 degrees relative to the central axis, preferably equal to or more than 7 degrees relative to the central axis and wherein the active surface of the sacrificial electrode preferably has an inclination equal to or less than 45 degrees relative to the central axis, preferably equal to or less than 35 degrees relative to the central axis.

5. The electrolysis cell according to any of the preceding claims, wherein the pin comprises an upper support surface having a shape adapted to receive the sacrificial electrode.

6. The electrolysis cell according to any of the preceding claims, wherein the pin is movable to allow adjusting the distance between the active surfaces of the electrodes in the interelectrode gap.

7. The electrolysis cell according to claim 6, wherein the pin is adapted to adjust the interelectrode gap to achieve a predetermined distance between the active surfaces of the electrodes.

8. The electrolysis cell according to claim 6 or 7 , wherein the pin is adapted to adjust the interelectrode gap to achieve a predetermined voltage between the electrodes.

9. The electrolysis cell according to any of the preceding claims, wherein the distance between the active surfaces of the electrodes in the interelectrode gap is between 0.5 and 15 mm, preferably between 0.5 and 10 mm, more preferably between 0.5 and 5 mm, even more preferably between 0.8 and 3 mm.

10. The electrolysis cell according to any of the preceding claims, wherein the inlet is at the bottom of the electrolysis cell.

11. The electrolysis cell according to any of the preceding claims, wherein the electrolysis cell comprises at least two inlets.

12. The electrolysis cell according to any of the preceding claims, wherein the electrolysis cell is adapted for introducing an electrolytic solution with a flow rate between 50 and 2050 kg / (h-m2).

13. The electrolysis cell according to any of the preceding claims, wherein the sacrificial electrode consists of layers of stacked blocks of conductive material, each layer preferably containing only a single block.

14. The electrolysis cell according to any of the preceding claims, wherein the electrolysis cell does not contain any further separating elements in the interelectrode gap.

15. Process for electrosynthesis of organic or organometallic compounds comprising the steps of a. introducing an electrolytic solution and one or more reactants into an electrolysis cell according to any of claims 1-14; b. applying a potential. wherein the organic or organometallic compounds are preferably insoluble in the electrolytic solution and wherein the electrolytic solution is preferably a non-aqueous solution.

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