EP3055385A1

EP3055385A1 - Proton sponge as supplement to electrolytes for photocatalytic and electrochemical co2 reduction

Info

Publication number: EP3055385A1
Application number: EP14802392.2A
Authority: EP
Inventors: Ralf Krause; Günter Schmid; Maximilian Fleischer; Philipp Grönninger; Mark Matzas; Kerstin Wiesner
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2013-11-26
Filing date: 2014-11-18
Publication date: 2016-08-17
Also published as: DE102013224077A1; CN105899646A; WO2015078731A1; US20160376714A1; CN105899646B; US10604853B2

Abstract

The invention relates to a method for converting carbon dioxide and water, wherein the electrolyte comprises a proton sponge which serves to accumulate CO₂ in the electrolyte. The invention further relates to a corresponding use of a proton sponge and to an electrolyte comprising at least one proton sponge.

Description

description

Proton sponges as an additive to electrolytes for photocatalytic and electrochemical CO ₂ reduction

The present invention relates to a process for the conversion of carbon dioxide and water, wherein said electrolyte comprises a proton sponge, which is used for the enrichment of C0 ₂ in the electrolyte, a corresponding use of proton sponge and an electrolyte comprising at least one proton sponge.

Background Art For a long time, the burning of fossil fuels was considered to be an environmentally friendly source of energy for the production of heat and electricity. The disposal of the carbon dioxide (C0 ₂ ) produced by combustion with air through the atmosphere was a very convenient way to dispose of even large quantities (lignite-fired power plants sometimes over 50,000 tons / day / power plant). The discussion about the negative effects of the greenhouse gas C0 ₂ on the climate has led to the idea of recycling C0 ₂ . From a thermodynamic point of view, C0 _{2 is} very low and therefore difficult to reduce back to useful products.

Photosynthesis reduces C0 ₂ to carbohydrates in nature. This temporally and on a molecular level spatially divided into many sub-steps process is very difficult to copy on an industrial scale. There are three ways a., B. and c. discuss how C0 ₂ can be reduced with the help of sunlight. a. The most complex and difficult route is photocatalysis. With the help of a catalyst, C0 ₂ should be converted directly into methane CH ₄ or methanol CH ₃ 0H in the presence of water. C0 ₂ + 2 H ₂ 0 - »CH ₄ + 2 0 ₂

C0 ₂ + 2 H ₂ 0 - »CH ₃ OH + 2 0 ₂ Normally, these processes" voluntarily "run as combustion only in the opposite form. Direct photocatalysis therefore inherently requires complex material logistics on the catalyst particle. In addition, the catalyst must be in an electrolyte, so that the material and charge balance can be compensated. This electrolyte, which is also suitable for the variants b. and c. is necessary, according to the prior art, however, still has no satisfactory

Properties for mass and charge transport. b. The C0 ₂ reduction catalyst and the H ₂ 0-Oxidationskatalystor can be purely formal as an electrode in an electrolytic system having a light-powered "voltage source" understand. In the following this is also defined as an electrically assisted photocatalysis. C0 ₂ -Reduktionselektrode and / or H ₂ 0-oxidant electrode are hereby photoelectrically active. c. In a further simplification the electrical energy to carry out the C0 ₂ reduction and H ₂ 0 oxidation comes from an external voltage source. this voltage source is particularly preferably operated by means of renewable energy sources such as wind or solar This process corresponds to a classical electrolysis Photochemical reduction of C0 ₂ :

The state of the art of photocatalysis, as shown in Table 1, shows that the photochemical conversion of C0 ₂ with water is only in the range of μπιοΐ / g / h even under good lighting conditions. For thermodynamic reasons, this is understandable. Table 1: Sales of C0 ₂ with water at different conditions and the products obtained therefrom according to the prior art

Reference Main Catalyst Max. light source

product yield

ACS Appl. Mater. CH ₄ W0 ₃ Nano- -1,1 300 W Xe BogenInterfaces 2012, sheet μπιοΐ / ^ ΐι lamp

4, 3372-3377

J. Phys. Chem. CH ₄ CdSe / Pt / Ti0 ₂ ~ 0.18 300 W Xe arc bed. 2010, 1, μπιοΐ / ^ ΐι lamp

48-53

Chem. Commun. , CH ₄ Pt-MgO / Ti0 ₂ -0.2 100 W Xe Bogen2013, 49, μπιοΐ / ^ ΐι lamp

2451-2453

Applied CH ₄ Ag-Ti0 ₂ -0.1 8W Hg lamp

Catalysis B: Enμπιοΐ / ^ ΐι

vironmental 96

(2010) 239-244

Phys. Chem. CO MgO -0.2 500 W UltraChem. Phys. , μπιοΐ / ^ ΐι hochdruck- 2001, 3, mercury lamp 1108-1113

Chem. Eur. J. CH ₄ Ti0 ₂ / ZnO -50 300 W Xe Bogen2011, 17, μπιοΐ / ^ ΐι lamp

9057 - 9061

Applied MeOH Cu / Ti0 ₂ -20 8W mercury

Catalysis B: Enμπιοΐ / ^ ΐι lamp

vironmental 37

(2002) 37-48

Applied CO I-Ti0 ₂ -2.4 100 W Xe Bogen¬

Catalysis A: Geμπιοΐ / ^ ΐι lamp

General 400 (2011)

195-202

Chem. Commun. , CH ₄ Pt-ZnGe0 ₄ -28 Xe full arc lam2011, 47, μmol / gh pe (fill arc Xe 2041-2043 lamp) Angew. Chem. ReviewInt. Ed. 2013, article

52, 2-39

When the reaction is carried out in air, the accumulation of C0 ₂ on the catalyst is a point of attack to increase the efficiency of the system. In addition to the enrichment of C0 ₂ , a certain amount of water should also be present in the reaction environment to provide the appropriate amount of protons. Here, the optimal ratio of H ₂ 0 and C0 _{2 play} an important role. The resulting major products vary depending on the catalyst, but very often in the literature reads CH ₄ and CO.

Electrochemical reduction of C0 ₂ :

It was not until the 1970s that systematic investigations of the electrochemical reduction of C0 _{2 began} . Despite many efforts, it has not yet been possible to develop an electrochemical system with which C0 ₂ could be reduced in the long term with a sufficiently high current density and acceptable yield and energy-efficient to competitive energy sources. Due to the growing scarcity of fossil fuels and the volatile availability of renewable energy sources, C0 ₂ reduction research is becoming more and more of a focus of interest. For the electrolysis of C0 ₂ metals are usually used as catalysts. In Table 2 (taken from: Y. Hori, Electrochemical CO 2 reduction on metal electrodes, in: C. Vayenas, et al. (Eds.), Modern Aspects of Electrochemistry, Springer, New York, 2008, pp. 89-189) show the typical Faayay efficiencies on various metal electrodes. Thus, C0 _2, for example, on Ag, Au, Zn, Pd, Ga almost exclusively CO, whereas on copper a variety of hydrocarbons are observed as reduction products. Table 2: Typical Faraday efficiencies for the reaction of C0 ₂ on various electrode materials

Electrode CH ₄ c ₂ H ₄ C ₂ H ₅ OH C ₃ H ₇ OH CO HCOO ^~ H ₂ Total

Cu 33 3 25 .5 5 .7 3 .0 1 .3 9 4 20 .5 103.5

Au 0 0 0 .0 0 .0 0 .0 87 .1 0 7 10 .2 98.0

Ag 0 0 0 .0 0 .0 0 .0 81 .5 0 8 12 .4 94.6

Zn 0 0 0 .0 0 .0 0 .0 79 .4 6 1 9 .9 95.4

Pd 2 9 0 .0 0 .0 0 .0 28 .3 2 8 26 .2 60.2

Ga 0 0 0 .0 0 .0 0 .0 23 .2 0 0 79 .0 102.0

Pb 0 0 0 .0 0 .0 0 .0 0 .0 97 4 5 .0 102.4

Hg 0 0 0 .0 0 .0 0 .0 0 .0 99 5 0 .0 99.5

In 0 0 0 .0 0 .0 0 .0 2 .1 94 9 3 .3 100.3

Sn 0 0 0 .0 0 .0 0 .0 7 .1 88 4 4 .6 100.1

Cd 1 3 0 .0 0 .0 0 .0 13 .9 78 4 9 .4 103.0

Tl 0 0 0 .0 0 .0 0 .0 0 .0 95 1 6 .2 101.3

Ni 1 8 0 .1 0 .0 0 .0 0 .0 1 4 88 .9 92.4

Fe 0 0 0 .0 0 .0 0 .0 0 .0 0 0 94 .8 94.8

Pt 0 0 0 .0 0 .0 0 .0 0 .0 0 1 95 .7 95.8

Ti 0 0 0 .0 0 .0 0 .0 0 .0 0 0 99 .7 99.7

In the following reaction equations, the reactions at the anode and at the cathode for the reduction on a silver cathode are shown by way of example. The reductions in the other metals are analogous to this.

Cathode: 2 C0 ₂ + 4 e ^" + 4 H ⁺ - 2 CO + 2 H ₂ 0

Anode: 2 H ₂ 0 -> ■ 0 ₂ + 4 H ⁺ + 4 e ^~

One of the primary problems with this electrolysis is that the electrolyte must be very conductive to have a small voltage drop, and at the same time, have good solubility of the C0 ₂ to provide sufficient C0 ₂ at the electrode for reduction. This is due to the low solubility of C0 ₂ in water (~ 3g C0 ₂ per 1 liter at 1 bar and 20 ° C) in the previously discussed aqueous systems are not possible. Especially at high current densities, the cleavage of water is dominant in these aqueous systems, since not enough C0 ₂ molecules are available at the cathode for reduction.

The use of ionic liquids for the reduction of C0 ₂ has been little described in the literature so far. In the following two publications are given, which work with the known compound [EMIM] BF ₄ (formula shown below):

Reduction of C0 ₂ to CO on silver electrode: BA Rosen, A. Salehi-Khoj in, MR Thorson, W. Zhu, DT Whipple, PJA Kenis, and RI Masel, Science 334, 643-644 (2011).

Reduction of C0 ₂ to CO at bismuth electrode:

J.L. DiMeglio, and Rosenthal Joel, Journal of the American Chemical Society 135, 8798-8801 (2013).

1-Ethyl-3-methylimidazolium tetrafluoroborate ([EMIM] BF ₄ )

In addition, US Pat. No. 5,788,666 also describes the use of immobilized proton scavengers for pH buffering. Further known from WO 2010/093092 is the use of polymers having an amine group for the precipitation of calcium carbonate, but not in electrochemical applications.

There is a need for an electrolyte and a method of reacting carbon dioxide and water with the aid of an electrolyte having improved efficiency in carbon dioxide conversion. Summary of the invention

It has been found according to the invention that the addition of proton sponges, which serve to enrich C0 ₂ in the electrolyte, for an electrolyte / electrolyte solution results in an increased efficiency in the conversion of carbon dioxide and water. The addition of proton sponges in electrolytes / electrolyte solutions, which surround, for example, a photocatalyst (in a photocatalysis) or an electrode (in an electrolysis), has the following advantages: According to Equation 1, the proton sponges have such a high

Tendency to bind protons, that the hygroscopy of the aqueous or non-aqueous electrolyte is increased so that water is also drawn from the air (PS = proton sponge)

Equation 1: PS + H ₂ 0 - »PS-H ⁺ + OH ^"

Especially in non-aqueous electrolytes are then highly active OH ^" ions, which are" neutralized "by C0 ₂ from the air and (hydrogen) carbonates form (equation 2). Thus, at the same time an enrichment of C0 ₂ takes place on the catalyst particles.

Equation 2: OH + C0 ₂ - »HCO ^3"

In the case of photocatalysis, therefore, an electrolyte (around the catalyst particle) is described which inherently promotes CO ₂ and H ₂ O absorption and thus increases the reaction rate. Sales and efficiency are thereby increased. The same reasoning applies to an electrolysis for the accumulation of C0 ₂ at the electrodes of an electrolytic cell. The invention thus relates, in a first embodiment, to a process for the conversion of carbon dioxide and water, characterized in that a liquid electrolyte or an electrolyte solution comprising at least one proton sponge is used, which serves for the enrichment of C0 ₂ in the electrolyte.

According to a further embodiment, the invention also relates to the use of a proton sponge in an electrolyte or an electrolyte solution in the reaction of carbon dioxide and water for the enrichment of C0 ₂ in the electrolyte. Furthermore, the invention also relates to an electrolyte or an electrolyte solution comprising at least one proton sponge.

Further aspects of the present invention can be found in the dependent claims and the detailed description.

Detailed Description of the Invention The term proton sponge includes certain aromatic ones

Diamines that have unusually high basicity constants. The aromatic diamines are based here on aromatics which have a naphthalene (partial) structure or fluorene (partial) structure in their framework structure, in which two functional groups derived from amines each at the 1- and 8-position in the case of naphthalene or at the 4- and

5-position of the fluorene, which are shown here.

Structured structures are currently known for proton sponges of great diversity

(http://de.wikipedia.org/wiki/Protonenschwamm, Stand

08/11/2013; Nuri Cenap Abacilar, "News from the chemistry of superbasic proton sponges based on guanidine,

Iminophosphorane and sulfoxime pincer ligands for protons ", Dissertation, University of Marburg, 2009).

Although naphthalene and fluorene are exemplified herein, the framework structure is not limited to these compounds, but includes skeletal structures that at least comprise these structures. Also, substitution on the framework structures is not excluded.

The high basicity constants result from the fact that the closely spaced amine groups in a mono-protonation reduce the destabilizing overlaps of the nitrogen-electron pairs and the strong steric strain. The strong N-H-N hydrogen bond further reduces the steric strain.

The term liquid electrolyte hereby includes both

Electrolytes in liquid as well as in molten form, for example, including a molten salt, and the term electrolyte solution includes electrolytes which are present in one or more solvents in dissolved form, the solvent preferably comprises water.

In the context of the present invention, the proton sponges are not immobilized in the liquid electrolyte or the electrolytic solution and are preferably not immobilized by further additives, but are in dissolved or suspended form freely mobile within the liquid electrolyte or the electrolyte solution and also mixable. A particular use of proton sponges is based on their effect as "carbonate scavengers", ie they have a high formation tendency of (hydrogen) carbonate salts, whereas nucleophilicity and puffing properties take a back seat, in particular embodiments according to the invention

polymer bound proton sponge is not included, since immobilization is not desired in the application. The electrolyte or the electrolytic solution should be able to compensate for charge gradient, or for the charge transport, the viscosity should be low, preferably <1000 cps, more preferably <100 cps, very preferably <10 cps. As stated above, the proton sponges according to Equation 1 have a high tendency to bind protons, so that the hygroscopicity of the aqueous or nonaqueous electrolyte is increased so much that water is also absorbed from the air

(PS = proton sponge)

Equation 1: PS + H ₂ 0 - »PS-H ⁺ + OH ^"

Equation 2: OH + C0 ₂ - »HCO ^3"

Since C0 ₂ passes from the air or from physical solution into a chemically dissolved state, the proton sponge serves as a "carbonate scavenger".

The invention in one aspect relates to a process for reacting carbon dioxide and water, wherein a liquid Electrolyte or an electrolyte solution comprising at least one proton sponge is used, wherein the proton sponge for the accumulation of C0 ₂ in the electrolyte is used. In this case, the proton sponge can be present in dissolved form or in suspended form in accordance with preferred embodiments. However, the proton sponge is preferably present in dissolved form so that it can also dissolve the carbon dioxide. Also, in this way, transportation to a reaction surface where the carbon dioxide reacts, for example, the surface of a photocatalyst or an electrode of an electrolytic cell is facilitated, and the surface is more easily accessible to the proton sponge.

According to preferred embodiments, the present process for the reaction is one in which the

Implementation is a photocatalysis. Photocatalyst is still not limited in any way, and may include any form that allows photocatalysis of carbon dioxide in principle. For example, photocatalysis may take place on surfaces corresponding to a solar collector. According to preferred embodiments, photocatalysis takes place using a ceramic photo-semiconductor, preferably TiO ₂ , ZnO, GaN, SrTiO ₃ , BaTiO ₃ , GaAs, MoS ₂ , WSe ₂ , MoSe ₂ and / or WO ₃ . Photo-semiconductors are materials that allow a conversion of light into electrical energy within a cell with two electrodes. In photocatalysis, this electrical energy is then used to implement a chemical reaction, such as a water electrolysis, in which case the photo-semiconductor preferably also acts as a catalyst. Suitable photo-semiconductors thus preferably have both a good absorption for light, a good conversion efficiency into electrical energy (for example, depending on the band gap of the material) and a catalytic activity in the chemical reaction of an introduced substance such as water. According to further preferred embodiments, in a process according to the invention for the reaction, the reaction relates to an electrolysis. Here, the cathode space and the anode space are not particularly limited. In the electrolysis, the carbon dioxide in the electrolyte may be present in dissolved and / or gaseous form, the proton sponge here then contributes as carbonate scavenger that carbon dioxide is increasingly converted into bicarbonate or carbonate and thus goes into solution. However, it is not excluded that gaseous carbon dioxide will continue to remain in the electrolyte.

From an environmental point of view, it is preferred in certain embodiments that the electrolyte is also present dissolved in water. The electrolyte is not particularly limited as long as it allows (possibly physical) dissolution of the carbon dioxide. For example, it may comprise KCl, K ₂ S0 ₄ , KHCO ₃ or mixtures thereof. In principle, all combinations of cations and anions can serve as conductive salts, which allow the required current densities.

The electrolysis may be carried out according to certain embodiments with a C0 ₂ reduction catalyst as the cathode and / or an oxidation catalyst as the anode. Here, the cathode-side reaction depends on material of the cathode, and is not limited. Examples of suitable cathode materials are copper, gold, silver, zinc, palladium, gallium, bismuth and mixtures or alloys of the materials. A preferred cathode material comprises copper, for example in an amount of 10 to 100 wt.%, Based on the cathode material, and preferably, the cathode is in

Essentially of copper or a copper alloy, preferably more than 90% by weight, more preferably more than 99% by weight, of copper. In principle, conductive optionally doped oxides such as TiO ₂ , NO, ITO (indium tin oxide), AZO (aluminum-doped zinc oxide), etc. are also suitable. The anode material is not particularly limited and includes all anode materials that can be used in the electrolysis of water, For example, anodes based on platinum, ruthenium or graphite.

According to certain embodiments, the cathode-side electrolyte and the anode-side electrolyte may be identical. In such embodiments, an electrolysis cell for the electrolysis according to the invention without membrane can manage. However, it is not excluded that the electrolytic cell in such embodiments has a membrane, but this is associated with additional expense in terms of the membrane as well as the applied voltage.

In certain embodiments, the electrolytic cell has a membrane which separates the cathode space and the anode space of the electrolytic cell to prevent mixing of the electrolytes. The membrane is not particularly limited insofar as it separates the cathode space and the anode space. In particular, it essentially prevents a transfer of carbon dioxide or its dissolved form to the anode. A preferred membrane is an ion exchange membrane, for example polymer based. A preferred material of an ion exchange membrane is a sulfonated tetrafluoroethylene polymer such as Nafion, for example Nafion 115. In addition to polymer membranes, ceramic membranes may also be used, e.g. mentioned in EP 1685892 AI.

The present invention further relates to the use of a proton sponge in a liquid electrolyte or an electrolyte solution in the reaction of carbon dioxide and water for the accumulation of C0 ₂ in the electrolyte. In use, the proton sponge may preferably be present dissolved or suspended in the electrolyte and is more preferably dissolved. Moreover, the present invention comprises an electrolyte or an electrolyte solution comprising at least one proton sponge. Here, the proton sponge may be preferred dissolved or suspended in the electrolyte and is particularly preferably dissolved.

The electrolyte is not particularly limited as long as it permits (possibly physical) dissolution of the carbon dioxide. For example, it may comprise KCl, K ₂ S0 ₄ , KHC0 ₃ or mixtures thereof. It is therefore not excluded that more than one compound is present in the electrolyte or the electrolyte solution. In principle, all combinations of cations and anions can serve as conductive salts, which allow the required current densities. In certain embodiments, the electrolyte may be organic cations such as guanidium and / or organo-substituted phosphonium, organo-substituted sulfonium, pyridinium, pyrrolidinium, morpholinium, ions, or the most common

Imidazoliumionen include. These can be used in the anode compartment, but also in the cathode compartment, since they can catalyze the reduction of C0 ₂ .

Exemplary of organic cations are therefore guanidinium pyridinium, pyrrolidinium, morpholinium, organically substituted phosphonium or sulfonium and imidazolium ions, which are the most common to call. Examples of suitable guanidinium cations include those of the following general formula (1):

In which the substituents R _± R _{6 are} in principle independently selected from the group of the linear, branched or cyclic C 1 -C 25 alkyl, C 6 -C 25 aryl, C 7 -C 25 alkylaryl, C 7 -C 25 arylalkyl, Cl C25 heteroalkyl, or C1 - C25 heteroaryl, C2 - C25 alkylheteroaryl, C2 - C25 Heteroarylalkylreste or hydrogen can be selected and also can be asymmetric. Furthermore, several of the substituents may also be bridged together via cyclic or heterocyclic compounds. The substituents R _± R _{6 of} the guanidinium cations can be selected, for example, from the group of the linear, branched or cyclic C 1 -C 25 alkyl, C 6 -C 25 aryl, C 7 -C 25 alkylaryl, C 7 -C 25

Arylalkyl, C 1 -C 25 heteroalkyl, or C 2 -C 25 heteroaryl, C 3 -C 25 alkylheteroaryl, C 3 -C 25 heteroarylalkyl, C 7 -C 25 heteroalkylaryl, C 7 -C 25 arylheteroalkyl, C 3 -C 25

Heteroalkylheteroaryl, C 3 -C 25 heteroarylheteroalkyl radicals, oligoether radicals (eg [-CH ₂ -CH ₂ -O-] _n ), where n can be an integer from 1 to 12, oligoesters (eg [-CH ₂ -CO-O-] _n ) where n can be an integer from 1 to 12, or

Oligoamides (eg [-C0-NR-] _n) or Oligoacrylamiden (eg [- CH ₂ -CHC0NH ₂ -] _n) where n is an integer of 1 - Be may be 12, or hydrogen selected.

Heteroalkyl- and heteroaryl radicals as well as the corresponding constituents in Alkylheteroaryl- or

Heteroaryl radicals here correspond to radicals or constituents in which a C atom of the alkyl chain or the aryl group is replaced by a heteroatom, for example N, S or O.

Exemplary guanidinium cations have, for example, the following formula (2):

Formula (2), where R _p = branched, unbranched or cyclic C 1 -C 20 -alkyl, C 6 -C 20 -aryl, C 7 -C 20 -alkylaryl,

C7 - C20 arylalkyl, Cl - C20 heteroalkyl -, or

Cl - C20 heteroaryl, C2 - C20 alkylheteroaryl -,

C2 - C20 heteroarylalkyl may be R _± and - R ₄ may be independently selected from the group of branched or unbranched C1-C20 alkyl, C6 - C20 aryl, C7 - C20 alkylaryl, C7 - C20 arylalkyl, Cl - C20 heteroalkyl or C2-C20 heteroaryl, C3-C20 alkylheteroaryl, C3-C20 heteroarylalkyl, C7-C20 heteroalkylaryl,

C7 - C20 Arylheteroalkyl-, C3 - C20 Heteroalyklheteroaryl -, C3 - C20 Heteroarylheteroalkylreste, (for example, [-CH2 _{_-CH2} -0-] _n), where an integer of 1 n - may be 12, oligoesters (for example [- CH ₂ -CO-] _n ) where n can be an integer from 1 to 12, or oligoamides (eg [-CO-NR-] _n ) or

Oligoacrylamiden (eg [-CH ₂ -CHC0NH ₂ -] _n ) where n can be an integer from 1 to 12, or hydrogen. Further examples of suitable organic cations are bis-guanidinium cations of the general formula (3)

Formula (3) The substituents R _± - R _u may independently of one another be linear, branched or cyclic C 1 -C 25 alkyl, C 6 -C 25 aryl, C 7 -C 25 alkylaryl, C 7 -C 25 arylalkyl, C 1 -C 20 heteroalkyl, or C2 - C25 heteroaryl, C3 - C25 alkylheteroaryl, C3 - C25 heteroarylalkyl, C7 - C25 heteroalkylaryl, C7 - C25 arylheteroalkyl, C3 - C25 heteroalkylheteroaryl, C3 - C25 heteroarylheteroalkyl radicals, or be hydrogen and also asymmetric or symmetrical bis -Guanidinium- Form cations. Furthermore, several of the substituents may also be bridged together via cyclic or heterocyclic compounds. Examples of organically substituted phosphonium ions are compounds of the general formula [R _f R _g R _h R _j P] ⁺ , where R _f , R _g , R _h and R _j independently of one another are selected from the group of the linear, branched or cyclic C 1 -C 25 -alkyl -, C6 - C25 aryl, C7 - C25 alkylaryl, C7 - C25 arylalkyl, C1 - C20 heteroalkyl or C2 - C25 heteroaryl, C3 - C25 alkylheteroaryl, C3 - C25 heteroarylalkyl, C7 - C25 Heteroalkylaryl -,

Can be C25 Heteroarylheteroalkylreste, or hydrogen selected, wherein at least one of R _f, R _g, R _h and R _j is not hydrogen - C7 - C25 Arylheteroalkyl-, C3 - C25 Heteroalyklheteroaryl -, C3. These, like the other cations mentioned, may also preferably be used in electrolytes in the cathode compartment.

Examples of organically substituted sulfonium ions are compounds of the general formula [R _f R _g R _h S] ⁺ , where R _f , R _g , and R _h independently of one another from the group of linear, branched or cyclic Cl - C25 alkyl, C6 - C25 aryl, C7-C25 alkylaryl, C7-C25 arylalkyl, C1-C20 heteroalkyl or C2-C25 heteroaryl, C3-C25 alkylheteroaryl, C3-C25 heteroarylalkyl, C7-C25 heteroalkylaryl,

C7 - C25 Arylheteroalkyl-, C3 - C25 Heteroalyklheteroaryl-, C3 - C25 Heteroarylheteroalkylreste, or hydrogen can be selected, wherein at least one of R _f, R _g, and R _h is not hydrogen. These, like the other cations mentioned, can also preferably be used in electrolytes in the cathode compartment.

Examples of pyridinium ions are compounds of the general formula [4], Wherein R and R ¹ - R ⁵ independently of one another from the group of the linear, branched or cyclic Cl - C25 alkyl, C6 - C25 aryl, C7 - C25 alkylaryl, C7 - C25 arylalkyl, Cl - C20 Heteroalkyl, or C2 - C25 heteroaryl,

C3 - C25 alkylheteroaryl, C3 - C25 heteroarylalkyl -,

C7 - C25 heteroalkylaryl, C7 - C25 arylheteroalkyl -,

C3 - C25 heteroalkyl heteroaryl,

C3 - C25 Heteroarylheteroalkylreste, or hydrogen may be selected. These, like the other cations mentioned, may also preferably be used in electrolytes in the cathode compartment. Examples of morpholinium ions are compounds of the general formula [5],

Formula [5] wherein RR 'and R ¹ - R ⁸ independently of one another from the group of linear, branched or cyclic

Cl - C25 alkyl, C6 - C25 aryl, C7 - C25 alkylaryl,

C7 - C25 arylalkyl, Cl - C20 heteroalkyl, or

C2 - C25 heteroaryl, C3 - C25 alkyl heteroaryl,

C3 - C25 heteroarylalkyl, C7 - C25 heteroalkylaryl,

C7 - C25 arylheteroalkyl, C3 - C25 heteroalkylheteroaryl, C3 - C25 heteroarylheteroalkyl radicals, or hydrogen can be chooses. These, like the other cations mentioned, may also preferably be used in electrolytes in the cathode compartment. Examples of pyrrolidinium ions are compounds of the general formula [6],

Formula [6] wherein RR '\ and R ¹ - R ⁸ independently of one another from the group of linear, branched or cyclic

Cl - C25 alkyl, C6 - C25 aryl, C7 - C25 alkylaryl,

C7 - C25 arylalkyl, Cl - C20 heteroalkyl -, or

C2 - C25 heteroaryl, C3 - C25 alkylheteroaryl -,

C3 - C25 heteroarylalkyl, C7 - C25 heteroalkylaryl -,

C7 - C25 arylheteroalkyl, C3 - C25 heteroalkylheteroaryl, C3 - C25 heteroarylheteroalkyl radicals, or hydrogen may be selected. These, like the other cations mentioned, can also preferably be used in electrolytes in the cathode space.

Examples of imidazolium ions are compounds of the general formula [7],

Formula [7] _{2 Q}

wherein R and R ¹ - R ⁴ independently of one another from the group of linear, branched or cyclic C 1 -C 25 alkyl, C 6 -C 25 aryl, C 7 -C 25 alkylaryl, C 7 -C 25 arylalkyl, C 1 -C 20 heteroalkyl, or C2 - C25 heteroaryl,

C3 - C25 alkylheteroaryl, C3 - C25 heteroarylalkyl -,

C7 - C25 heteroalkylaryl, C7 - C25 arylheteroalkyl -,

C3 - C25 heteroalkyl heteroaryl -,

C3 - C25 Heteroarylheteroalkylreste, or hydrogen may be selected. These, like the other cations mentioned, can likewise preferably be used in electrolytes in the cathode compartment.

According to certain embodiments, the proton sponge has the general formula (I):

where n = 0 or 1;

Al and A2 represent aromatic skeletons, for example a benzene or naphthalene skeleton, which may be linked by another ring A3, where

when n = 1, A3 is present and represents a substituted or unsubstituted cyclopentane ring or ring which shares the bond with the aromatic skeleton AI at positions 1 and 2 and the bond with the aromatic skeleton A2 at positions 3 and 4 and the carbon at position 5 in the formula below is present between Al and A2 and may have two substituents R ^d and R ^d> ;

where R ^d and R ^d> independently of one another denote hydrogen and / or one or more substituted or not substituted substituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic Res th with 1 to 40 carbon atoms, wherein when R ^d and R ^d are present, these together one may form aliphatic or aromatic ring or polycycles;

when n = 0, ring A3 is absent and rings AI and A2 are condensed;

wherein R ^w , R ^x , R ^y and R ^z independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 50 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 100 C Atoms and / or substituted or unsubstituted linear or branched sulfonylalkyl radicals having 1 to 50 carbon atoms represent where 2 or more of R ^x to R ^{z can} together form a ring or polycycles and wherein in each case both R and R ^x and R ^Y and R ^{z can be} replaced by forming a double bond on the nitrogen by a single radical R ^w or R ^Y , respectively; and

wherein R ^a and R ^b independently represent hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C-atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic Res te having 1 to 40 Represent carbon atoms on the respective ring of the aromatic body, wherein if 2 or more R ^a and / or R ^b are present, these together can form an aliphatic or aromatic ring or polycycles. However, R ^a and R ^b in formula (I) preferably represent hydrogen.

Preferred radicals R ^w , R ^x , R ^y and R ^z are independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 3 to 50 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 100 C atoms and / or substi- substituted or unsubstituted linear or branched sulfonylalkyl having 1 to 50 carbon atoms, wherein 2 or more of R ^x to R ^{z may} together form a ring or polycycles and wherein each of R ^w and R ^x and R ^Y and R ^z by Forming a double bond on the nitrogen by a single radical R ^w or R ^Y can be replaced.

Suitable substituents for the radicals R ^w, R ^x, R ^y, R ^z, R ^a and R ^b are both heteroatoms, such as N, P, 0, S in the alkyl chain as well as substituents for the hydrogen atoms of the alkyl chain, for example, halogen atoms such as F , Cl, Br, I, preferably F, -CF ₃ or -CN. In this case, two or more heteroatoms may be linked in the alkyl chain, for example P and N or S and 0. Suitable heteroatoms for the heteroaromatic are, for example, N , P, 0, S.

Suitable radicals R ^w, R ^x, R ^y, R ^z, R ^a and R ^b may thus, for example, independently be methyl, ethyl, generalized straight, branched, condensed

(Decahydronaphthyl -), cyclic (cyclohexyl) - or fully or partially substituted Cl - C20 be alkyl radicals, as well as ether groups (ethoxy, methoxy, etc.), esters, amide, carbonate groups, -CN, etc, and also like also contain ether groups (ethoxy, methoxy, etc.), esters, amide, carbonate groups, and contain as substituents, for example, halogens, in particular F, -CF ₃ or -CN. For the purposes of the invention, substituted or unsubstituted aliphatic rings or ring systems, such as cyclohexyl are. R ^w , R ^x , R ^y , R ^z , R ^a and R ^b are not limited to saturated systems, but also include, for example, substituted or unsubstituted aromatics such as phenyl, diphenyl,

Naphthyl, phenanthryl, etc., or benzyl, etc. An exemplary compilation of suitable

Heterocycles for the radicals R ^w , R ^x , R ^y , R ^z , R ^a and R ^b is shown in the following view, in the sake of simplicity only the main body of the aromatic is shown, in principle, these bodies may be substituted with further substituted linear, branched or cyclic alkyl radicals and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals, wherein the definition of suitable substituents and heteroatoms analog the definition of the radicals R ^w , R ^x , R ^y , R ^z , R ^a and R ^b . In the Bypyridine system, X _± to X ₁₂ can represent both C and N. Binding to the aromatic skeleton Al and / or A2 and / or to alkyl or substituted alkyl radicals on the aromatic skeleton can be carried out at any bondable site of the main body.

The above formula (I) is capable of subsuming two formulas (Ia) and (Ib) which represent the formula for n = 0 and n = 1, respectively, and are shown below.

The formula (Ia) here represents the cases in which the two aromatics AI and A2 are condensed, whereas the formula (Ib) represents those cases in which the two aromatics AI and A2 are "linked" via a five-membered ring Formulas (Ia) and (Ib) here have R ^w , R ^x , R ^y and R ^z and R ^a and R ^{b have} the same meaning as in the general formula (I) above. Preferred is the compound of formula (Ia).

Preferred as the proton sponge of the present invention, for example as the compound of formula (I), is a compound of the following formulas (II), (III), (IVa); (IVb), (Va) or (Vb):

wherein R ¹ to R ⁴ independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or not substituted aromatic and / or heteroaromatic radicals having 1 to 40 carbon atoms and / or substituted or unsubstituted linear or branched sulfonylalkyl having 1 to 20 carbon atoms, wherein 2 or more of R ¹ to R ⁴ together form an aliphatic or aromatic ring or can form polycycles; and

wherein R ^a and R ^b independently of one another hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C-atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to Represent 40 C atoms on the respective ring of Naphthalingrundkörpers, wherein if 2 or more R ^a and / or R ^b are present, these together an aliphatic or aromatic ring or

Can form polycycles;

wherein R ⁵ to R ⁸ independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 carbon atoms and / or substituted or unsubstituted linear or branched sulfonylalkyl having 1 to 20 carbon atoms, wherein 2 or more of R ⁵ to R ^{8 may} together form an aliphatic or aromatic ring or polycycles; and

where R ^a and R ^b independently of one another denote hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C

Atoms and / or substituted or unsubstituted aromatic represent tables and / or heteroaromatic radicals having 1 to 40 carbon atoms on the respective ring of the Fluorengrundkörpers, where if 2 or more R ^a and / or R ^b are present, these together form an aliphatic or aromatic ring or

Can form polycycles; and

where R ^d and R ^d> independently of one another hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals with 1 to 40 carbon atoms, wherein when R ^d and R ^d> are present, these together form an aliphatic or aromatic ring or

Can form polycycles;

where R ¹¹ to R ¹⁴ are each independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C atoms and / or substituted or not substituted linear or branched sulfonylalkyl having 1 to 20 carbon atoms, wherein 2 or more of R ¹¹ to ^{R14 may} together form an aliphatic ring or polycycles; and

where R ^a and R ^b independently of one another are hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to Represent C atoms on the respective ring of the naphthalene skeleton, where if 2 or more R ^a and / or R ^b are present, these together form an aliphatic or aromatic ring or

Can form polycycles;

where R ²¹ to R ²⁸ independently of one another represent hydrogen and / or substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C atoms wherein 2 or more of R ²¹ to R ^{28 may} together form an aliphatic or aromatic ring or polycycles; and

Can form polycycles; where R ³¹ to R ³⁶ and R ^31> to R ^36> independently of one another hydrogen and / or substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 carbon atoms and / or one or more of in each case R ³¹ and R ³¹ , R ³² and R ^32> , R ³³ and preferably R ³² and R ^32> and R ³⁵ and R ^{35 represent} , forming a double bond instead of the two substituents, a phosphazene derivative P (NR ^C ₂ ) ₃ , where 2 or more of R ³¹ to R ³⁶ and R ^31> to R ^{36 >} and / or R ^{c may} together form an aliphatic or aromatic ring or polycycles;

wherein the R ^c independently represent one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C atoms; and wherein R ^a and R ^b independently of one another are hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 represent C atoms on the respective ring of the naphthalene skeleton, wherein when 2 or more R ^a and / or R ^b are present, they together form an aliphatic or aromatic ring or

Polycycles can form. Preferred radicals R ¹ to R ⁴ in formula (II) are independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 3 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C And / or substituted or unsubstituted linear or branched sulfonylalkyl having 1 to 20 carbon atoms, wherein 2 or more of R ¹ to R ^{4 may} together form an aliphatic or aromatic ring or polycycles.

However, R ^a and R ^b in formulas (II), (III), (IVa), (IVb), (Va) and (Vb) preferably represent hydrogen, and / or R ^d and R ^d> in formula ( III) is hydrogen. Suitable substituents for the radicals R ¹ to R ⁸ , R ¹¹ to R ¹⁴ ,

R ²¹ to R ²⁸ , R ³¹ to R ³⁶ , R ^31> to R ^a and R ^b and R ^c and R ^d in formulas (II), (III), (IVa), (IVb), (Va) and (Vb) represent both heteroatoms such as N, P, O, S in the alkyl chain and also as substituents for the hydrogen atoms of the alkyl chain, for example halogen atoms such as F, Cl, Br, I, preferably F, -CF ₃ or -CN. In this case, two or more heteroatoms may also be linked in the alkyl chain, for example P and N or S and 0. Suitable heteroatoms for the heteroaromatic compounds are, for example, N, P, O, S.

Suitable radicals R ¹ to R ⁸ , R ¹¹ to R ¹⁴ , R ²¹ to R ²⁸ , R ³¹ to R ³⁶ , R ^31> to R ^a and R ^b and R ^c and R ^d in formulas (II), (III), (IVa), (IVb), (Va) and (Vb) can thus, for example, independently of one another methyl, ethyl, generalized branched, branched, fused (decahydronaphthyl), cyclic (cyclohexyl) or fully or partially substituted C 1 -C 20 alkyl radicals, as well as ether groups (ethoxy, methoxy, etc.), esters, amide, carbonate groups, -CN, etc, and also as well as ether groups (ethoxy, methoxy, etc.), esters, amide, carbonate groups, and contain as substituents, for example, halogens, in particular F, or -CN. For the purposes of the invention are also substituted or unsubstituted aliphatic rings or ring systems, such as cyclohexyl. R ¹ to R ⁴ in formula (II) are preferably not methyl and ethyl radicals. R ¹ to R ⁸ , R ¹¹ to R ¹⁴ , R ²¹ to R ²⁸ , R ³¹ to R ³⁶ , R ^31> to R ^a and R ^b and R ^c and R ^d in formulas (II), (III), (IVa), (IVb), (Va) and (Vb) are not limited to saturated systems, but also include, for example, substituted or unsubstituted aromatics such as phenyl, diphenyl, naphthyl, phenanthryl, etc., or benzyl, etc.

An exemplary compilation of suitable

Heterocycles for the radicals R ¹ to R ⁸ , R ¹¹ to R ¹⁴ , R ²¹ to R ²⁸ , R ³¹ to R ³⁶ , R ^31> to R ^a and R ^b and R ^c and R ^d in formulas (II), (III), (IVa), (IVb), (Va) and (Vb) are in the above

View with respect to R ^w , R ^x , R ^y , R ^z , R ^a and R ^b shown, in the sake of simplicity, only the main body of the aromatics is shown, in principle, these bodies with other substituted linear, branched or cyclic alkyl radicals and or substituted or unsubstituted aromatic and / or heteroaromatic radicals, where the definition of the suitable substituents and heteroatoms is analogous to the definition of the radicals R ^w , R ^x , R ^y , R ^z , R ^a and R ^b results. In the Bypyridine system, X _x to Xi 2 can represent both C and N. Binding to the aromatic skeleton Al and / or A2 and / or to alkyl or substituted alkyl radicals on the aromatic skeleton can be carried out at any bondable site of the main body. Further preferred are proton sponges of the formulas (III), (IVa), (IVb), (Va) and (Vb).

Examples of proton sponges in the context of the invention are the following compounds:

Substituted and unsubstituted compounds based on 1,8-diaminonaphthalene derivatives: For example: N, N, N ', N'-tetraalkyl or aryl-1,8-naphthalenediamines of the formula (II)

Particularly high basicities are possessed by the "guanidino" -substituted 1,8-naphthalene derivatives of the formula (Va).

An exemplary compound is the compound of Formula 5 ^* .

For the purposes of the invention are also the sulfonamide derivatives of the formula (IVa). In particular, all compounds and references within the meaning of this invention disclosure, which are described in the thesis "What's New in the Chemistry of Supersasic Proton Sponges Based on Guanidine, Iminophosphorane and Sulfoximine Pinzette Ligands for Protons" by Nuri Cenap Abacilar from Hanau, Marburg / Lahn, 2009 , from the Department of Chemistry of the Philipps University

(19.08.2009). In particular, phosphazene derivatives such as those of the general formula (Vb) are described here, of which exemplified compounds of the formulas 3, 8 and 7 ^* are shown below.

The use according to the invention of the proton sponges as an additive to an electrolyte also includes the electrolyte itself. In addition to the proton sponge, it may contain other customary additives, such as are used in, for example, photocatalysis or electrolysis, and which are not particularly limited within the scope of the invention.

According to certain embodiments, the electrolyte solution comprises water and at least one conducting salt. Furthermore, the electrolyte is not particularly limited in this case as long as it permits (possibly physical) dissolution of the carbon dioxide. examples For example, it may comprise KCl, K ₂ S0 ₄ , KHC0 ₃ or mixtures thereof as the conductive salt. In principle, all combinations of cations and anions can serve as conductive salts, which allow the required current densities, such as those mentioned above.

In addition, the liquid electrolyte or the electrolytic solution of the present invention may comprise at least one ionic liquid.

Exemplary and preferred are ionic liquids based on:

Imidazolium, pyridinium, pyrollidinium, piperidinium, guanidinium cations, with corresponding anions.

These may be halides, or complex halides such as BF ₄ ^" or PF ₆ ^" , carboxylates, sulfates, triflates,

Bis (trifluoromethanesulfone) imide, carbonate or bicarbonate, etc., more preferably carbonate or bicarbonate.

As ionic liquids, organic salts having a melting point below 300 ° C., preferably below 100 ° C., particularly preferably below 50 ° C., are designated. Table 3 and list below list possible examples of suitable ionic liquids.

_.

Table 3: Exemplary ionic liquids

Table 3 (continued!

Table 3 (continued)

1-Butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide 1 -butyl-3-methylimidazolium methanesulfonate

Tetrabutylammoniumbis-trifluoromethansulfonimidat

tetrabutylammonium methanesulfonate

Tetrabutylammoniumnonafluorobutansulfonat

Tetrabutylammoniumheptadecafluorooctansulfonat

Tetrahexylammoniumtetrafluoroborat

Tetrabutylammoniumtrifluoromethansulfonat

tetrabutylammonium benzoate

tetrabutylammonium

1-Benzyl-3-methylimidazolium tetrafluoroborate

Trihexyltetradecylphosphoniumhexafluorophosphat

Tetrabutylphosphoniummethansulfonat

Tetrabutylphosphoniumtetrafluoroborat

tetrabutylphosphonium

1-Butyl-3-methylpyridinium bis (trifluoromethylsulfonyl) imide

1-butyl-4-methylpyridinium hexafluorophosphate

1-butyl-4-methylpyridinium tetrafluoroborate

tetrabutylammonium

sodium tetraphenylborate

Sodium tetrakis (1-imidazolyl) borate

Caesiumtetraphenylborat

Furthermore, the electrolyte may also comprise supercritical C0 ₂ itself. However, then water must be supplied depending on consumption.

According to certain embodiments, the liquid electrolyte according to the invention or the electrolytic solution according to the invention comprises at least one polar or nonpolar organic solvent, in particular an alcohol with more than 5 carbon atoms, a high-boiling ether with a boiling point of more than 80 ° C, preferably 150 ° C, a high-boiling amine with a boiling point of more than 80 ° C, preferably 150 ° C, or a liquid under electrolysis conditions polyamide. In particular, the liquid electrolyte or the electrolyte solution

- consist mainly or partially of water. In particular, high-boiling additives are of advantage (high-boiling additives)

Alcohols from six carbon atoms, ether (polyethylene glycol), or amines and liquid polyamides), so that the electrolyte can not evaporate even during prolonged operation. The defined addition of water can change the product spectrum, especially in the case of electrochemical reduction. Depending on the potential and the available C0 ₂ concentration (in aqueous systems controllable via the pressure and the temperature), a mixture of different hydrocarbon compounds such as CH ₄ , C ₂ H ₄ , CO, etc. is formed on a copper cathode desired hydrocarbon such as CH ₄ are shifted by selective adjustment of the ratio of proton sponge to water. If, on the other hand, a reduction of CO ₂ to CO is to be achieved, it can be ensured by the absence of water that no undesirable additional hydrogen evolution is observed, but all electrons are used to reduce CO ₂ (Faraday efficiency of approximately 100%) % of CO).

- polar or non-polar organic solvents, such as high-boiling alcohols from six carbon atoms, ethers

(Polyethylene glycol), or amines (pyridine, quinoline, etc.) and polyamides.

By nature, ionic liquids have only a very low or virtually no vapor pressure and are therefore very well suited as solvents for the organic proton sponges.

In principle, the compositions thus prepared can be used in processes for the reaction of CO ₂ and water, for example photocatalysis or electrolysis, of CO ₂ or carboate-containing electrolytes at lower temperature, in particular Room temperature, ie 15 - 30 ° C, preferably about 20 to 25 ° C, can be used.

Particularly preferred is the use in a panel for the photocatalytic reduction of C0 ₂ in the presence of water.

For example, the panel is provided with means for separating products such as methanol or methane. The electrolyte encloses, for example, the catalytically active particles and thus ensures that material and electron cycles are closed.

The photocatalytic reduction of C0 ₂ to methanol, methane or other energy sources or basic chemicals has so far only given very poor yields in the range of

μπιοΐ / h per gram of catalyst used. An optimization measure is to increase the concentration of protons and CO ₂ on the catalyst particle to increase the likelihood that the reaction can take place. This can be achieved according to the invention.

In the case of electrochemical reduction, the efficiencies, for example, by reducing the overvoltage at the cathode during electrolysis, can be improved by using the proton sponges discussed here. In the systems discussed so far in the literature, the efficiency for commercial use is currently too poor. In addition to improving the efficiency of the selectivity (reduction to a desired hydrocarbon, suppressing the formation of other reduction products), especially in the electrolysis, especially at high current densities, improve. This can be achieved by selectively providing the cathode with sufficient CO ₂ and H ₂ O for the formation of a particular hydrocarbon.

Claims

claims

1. A process for the conversion of carbon dioxide and water, characterized in that a liquid electrolyte or an electrolyte solution comprising at least one proton sponge, is used, which serves for the enrichment of C0 ₂ in the electrolyte.

2. A method for the reaction according to claim 1, wherein the proton sponge in the liquid electrolyte or the electrolyte solution is dissolved or suspended.

3. A method of implementation according to claim 1 or 2, wherein the reaction is a photocatalysis.

4. A method for the reaction according to claim 3, wherein the photocatalysis using a ceramic photo semiconductor, preferably of Ti0 ₂ , ZnO, GaN, SrTi0 ₃ , BaTi0 ₃ , GaAs, MoS ₂ , WSe ₂ , MoSe ₂ and / or W0 ₃ , takes place ,

5. A process for the reaction according to claim 1 or 2, wherein the reaction is an electrolysis.

6. The method according to claim 5, wherein the electrolysis with a C0 ₂ -reduction catalyst as the cathode and / or

an oxidation catalyst is carried out as an anode.

7. The method according to claim 6, wherein the cathode Cu, Au, Ag, Zn, Pd, Bi or Ga, preferably Cu, contains.

8. Use of a proton sponge in a liquid

Electrolytes or an electrolyte solution in the conversion of carbon dioxide and water for the enrichment of C0 ₂ im

Electrolytes.

9. Use according to claim 8, wherein the proton sponge is dissolved or suspended in the electrolyte.

10. Liquid electrolyte or electrolyte solution comprising at least one proton sponge.

11. The liquid electrolyte or electrolyte solution according to claim 10, wherein the proton sponge is dissolved or suspended in the electrolyte.

12. The liquid electrolyte or electrolytic solution according to claim 10 or 11, wherein the proton sponge has the general formula (I):

where n = 0 or 1;

if n = 1, A3 is present and represents a substituted or unsubstituted cyclopentane ring which shares the bond with the aromatic skeleton AI at positions 1 and 2 and the bond with the aromatic skeleton A2 at positions 3 and 4 and the carbon is present at position 5 in the formula below between Al and A2 and may have two substituents R ^d and R ^d> ;

wherein R ^d and R ^d> independently of one another hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic Radicals having 1 to 40 carbon atoms, wherein when R ^d and R ^d> are present, they together can form an aliphatic or aromatic ring or polycycles;

if n = 0, ring A3 is absent and rings AI and A2 are condensed;

wherein R ^w , R ^x , R ^y and R ^z independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 50 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 100 C Atoms and / or substituted or unsubstituted linear or branched sulfonylalkyl radicals having 1 to 50 carbon atoms, where 2 or more of R ^x to R ^{z may} together form a ring or polycycles and wherein in each case both R ^w and R ^x as also R ^Y and R ^z through

Forming a double bond on the nitrogen can be replaced by a single radical R ^w or R ^Y ; and

where R ^a and R ^b independently of one another are hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to Represent C atoms on the respective ring of the naphthalene skeleton, where if 2 or more R ^a and / or R ^b are present, these together can form an aliphatic or aromatic ring or polycycles.

13. The liquid electrolyte or electrolytic solution according to any one of claims 10 to 12, wherein the proton sponge is a compound of the following formulas (II), (III), (IVa), (IVb), (Va) or (Vb);

(II) wherein R ¹ to R ⁴ independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 carbon atoms and / or substituted or unsubstituted linear or branched sulfonylalkyl having 1 to 20 carbon atoms, wherein 2 or more of R ¹ to R ^{4 may} together form an aliphatic or aromatic ring or polycycles; and

wherein R ^a and R ^{b are} independently hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C Represent atoms on the respective ring of the naphthalene skeleton, wherein when 2 or more R ^a and / or R ^b are present, they may together form an aliphatic or aromatic ring or polycycles;

where R ⁵ to R ⁸ are each independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C atoms and / or substituted or unsubstituted linear or branched Represent sulfonylalkyl having 1 to 20 carbon atoms, wherein 2 or more of R ⁵ to R ^{8 may} together form an aliphatic or aromatic ring or polycycles; and

where R ^a and R ^b independently of one another are hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 Represent carbon atoms on the respective ring of Fluoreng round body, wherein when 2 or more R ^a and / or R ^b are present, they together can form an aliphatic or aromatic ring or polycycles; and

where R ^d and R ^d> independently of one another hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to Represent 40 C atoms, wherein when R ^d and R ^c are present, they may together form an aliphatic or aromatic ring or polycycles;

0 RR ^{± J} 0

(Iva)

wherein R ¹¹ to R ¹⁴ independently substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 carbon atoms and / or substituted or unsubstituted linear or branched sulfonylalkyl having 1 to 20 carbon atoms, wherein 2 or more of R ¹¹ to R ^{14 may} together form an aliphatic ring or polycycles; and wherein R ^a and R ^b independently of one another are hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C atoms at the respective ring of the

Represent naphthalene skeletons, wherein when 2 or more R ^a and / or R ^b are present, they may together form an aliphatic or aromatic ring or polycycles;

where R ²¹ to R ²⁸ independently of one another represent hydrogen and / or substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C atoms wherein 2 or more of R ²¹ to R ²⁸ together form an aliphatic or aromatic ring or polycycles; and

wherein R ^a and R ^{b are} independently hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C -Atomen at the respective ring of the

wherein R ³¹ to R ³⁶ and R ^31> to R ^36> independently of one another hydrogen and / or substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 C atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 carbon atoms and / or one or more of each of R ³¹ and R ³⁵ and preferably R ³² and R ^32> and R ³⁵ and

R ³⁵ , to form a double bond instead of the two substituents represent a phosphazene derivative P (NR ° ₂ ) 3, wherein 2 or more of R ³¹ to R ³⁶ and R ^31> to R ^36> and / or R ^c together form an aliphatic or aromatic Can form ring or polycycles;

wherein the R ^c independently of one another one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 carbon atoms; and

wherein R ^a and R ^{b are} independently hydrogen and / or one or more substituted or unsubstituted linear, branched or cyclic alkyl radicals having 1 to 20 carbon atoms and / or substituted or unsubstituted aromatic and / or heteroaromatic radicals having 1 to 40 C Represent atoms on the respective ring of the naphthalene in-body, wherein when 2 or more R ^a and / or R ^b are present, these together can form an aliphatic or aromatic ring or polycycles.

14. The liquid electrolyte or electrolyte solution according to any one of claims 10 to 13, wherein the electrolyte solution further comprises water and at least one conductive salt.

The liquid electrolyte or electrolytic solution according to any one of claims 10 to 14, wherein the electrolytic solution comprises at least one ionic liquid.

16. A liquid electrolyte or electrolyte solution according to any one of claims 10 to 15, wherein the electrolyte solution comprises at least one polar or nonpolar organic solvent, in particular an alcohol having more than 5 carbon atoms, a high-boiling ether, a high-boiling amine or a liquid polyamide.