WO2020156734A1 - Procédé de fabrication de co à bon rendement énergétique - Google Patents

Procédé de fabrication de co à bon rendement énergétique Download PDF

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Publication number
WO2020156734A1
WO2020156734A1 PCT/EP2019/085669 EP2019085669W WO2020156734A1 WO 2020156734 A1 WO2020156734 A1 WO 2020156734A1 EP 2019085669 W EP2019085669 W EP 2019085669W WO 2020156734 A1 WO2020156734 A1 WO 2020156734A1
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Prior art keywords
formic acid
formate
mixture
cathode
anode
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German (de)
English (en)
Inventor
Günter Schmid
Christian Reller
Dan Taroata
Nemanja Martic
David Reinisch
Bernhard Schmid
Thomas Reichbauer
Ralf Krause
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Siemens AG
Siemens Corp
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Siemens AG
Siemens Corp
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Publication of WO2020156734A1 publication Critical patent/WO2020156734A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/40—Carbon monoxide
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/25—Reduction
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/141—Feedstock

Definitions

  • the present invention relates to a method for the produc- tion of CO from CO2, and an apparatus for performing the method.
  • Natural carbon dioxide degradation takes place, for example, through photosynthesis.
  • carbon dioxide is converted into carbohydrates in a process that is divided into many sub-steps in terms of time and on a molecular level. This process is not easily adaptable on a large scale. A copy of the natural photosynthesis process with large-scale photo catalysis has not been sufficiently efficient so far.
  • Electrolysis of carbon dioxide preferably metals are to be used as catalysts.
  • Electrochemical C0 2 reduction on metal electrodes by Y. Hori, published in: C. Vayenas, et al. (Eds.), Modern Aspects of Electrochemistry, Springer, New York, 2008, pp. 89-189, for example, Faraday efficiencies can be taken from different metal cathodes, see Table 1, which is taken from there. Table 1: Faraday efficiencies for C0 2 at different
  • Carbon monoxide C0 2 + 2 e + H 2 0 - ⁇ CO + 2 OH
  • the energy efficiency of the single-stage electrochemical reduction of C0 2 depends not only on the overvoltages on the electrodes, the ohmic losses in the electrolyte and / or on the membranes, but also on the selected mode of operation of the electrolysis cell (stacks), since the electrolysis cell operates asymmetrically becomes.
  • C0 2 is reduced at the cathode and H 2 0 is oxidized at the anode.
  • the side reactions or buffer reactions of the reaction by-products hydrooxide, proton, hydrogen carbonate formation
  • the minimum voltage of a cell can be derived from the enthalpy of combustion from CO to CO2, since electrolysis is purely formal the reversal of the combustion. Analogously, these considerations naturally also apply to other possible reaction products of electrochemical CO 2 reduction, such as ethylene, ethanol, methane, acetate, formic acid, formate, etc.
  • the cell voltage for the reaction 2 CO2 -> 2 CO + O2 in aqueous media is 2.04 V, in contrast to 1.47 V in the gas phase analysis . This means that when reducing CO2 to CO in aqueous media, from a purely thermodynamic perspective, more electrical energy must be used than would be required for the actual reduction.
  • Part of this thermal energy can be used to decompose CO2 in the anode compartment from hydrogen carbonate:
  • the cell voltage is 1.47 V.
  • the object of the present invention is to largely avoid the conversion of valuable electrical energy into thermal waste heat by means of a suitable sequence of electrochemical and thermal processes, without going back to a complex process which is highly complex and difficult to scale.
  • the inventors have found that the waste heat and energy loss can be reduced or even avoided by decoupling the generation of the CO from the cathode reaction.
  • the present invention relates to a method for producing CO from CO2 comprising electrolytic conversion of a starting material comprising CO 2 to a mixture comprising formic acid and / or formate in a first electrolytic cell,
  • the invention also relates to a process for the electrolytic conversion of a starting material comprising CO to a mixture comprising at least one hydrocarbon, the reaction being carried out in the presence of a basic electrolyte, preferably the anode comprising Fe, Ni and / or NiFe.
  • a device for producing CO from CO 2 comprising
  • a first electrolysis cell comprises a first cathode and a first anode for the electrolytic reaction of a starting material CO 2, which is comprising comprising a mixture comprising formic acid and / or formate adapted to fully implement a reactant umfas send CO 2 to a mixture of formic acid and / or formate ;
  • a first supply device for an educt comprising CO 2 to the first electrolytic cell which is designed with the first electrolytic cell to supply an educt comprising CO 2 to the first cathode;
  • a first discharge device for a mixture comprising formic acid and / or formate which is connected to the first electrolytic cell in a region between the first cathode and the first anode and which is designed to produce a mixture comprising formic acid and / or formate from the first Dissipate electrolytic cell;
  • a first reactor for releasing a product comprising CO from the mixture comprising formic acid and / or formate which is designed to produce a product comprising CO from the Mixture comprising formic acid and / or formate to release;
  • a second feed device for the mixture comprising formic acid and / or formate which is connected to the first reactor and is designed to supply the mixture comprising formic acid and / or formate to the first reactor;
  • a second discharge device for discharging the product comprising CO from the first reactor, which is designed to discharge the product comprising CO from the first reactor.
  • FIGS 1 to 4 show schematically theoretical stages of the electrochemical conversion of CO2 to CO.
  • FIGS 5 to 8 schematically show theoretical stages of the electrochemical conversion of CO2 in acid.
  • FIGS. 9 to 12 show schematically energetic considerations for the conversion of CO2 to CO via various electrochemical routes.
  • FIG. 13 schematically shows an exemplary device according to the invention for producing CO from CO2.
  • FIGS. 14 to 16 show results from reference measurements in the examples according to the invention.
  • hydrophobic is understood to mean something which repels serum. Hydrophobic pores and / or channels are therefore those that repel water. In particular, according to the invention, hydrophobic properties are associated with substances or molecules with non-polar groups.
  • Gas diffusion electrodes in general are electrodes in which liquid, solid and gaseous phases are present, and where in particular a conductive catalyst can catalyze an electrochemical reaction between the liquid and the gaseous phase.
  • the design can be of different types, for example as a porous “solid catalyst” with possibly auxiliary layers to adjust the hydrophobicity, or as a conductive porous carrier on which a catalyst in thin
  • a gas diffusion electrode is in particular a porous electrode, inside which gases can move through diffusion.
  • GDE gas diffusion electrode
  • it can be designed to separate a gas and an electrolyte space from one another.
  • product gases can escape from these gas diffusion electrodes on the side facing away from the counterelectrode, that is to say, for example, into a gas space to which a gas is supplied for conversion.
  • Liquids and / or dissolved products and / or by-products of the electrochemical conversion, in particular the charge carriers generated thereby can be released, for example, from the electrode into the electrolyte.
  • a GDE can be built up in one or more layers with hydrophilic and / or hydrophobic regions, with at least one hydrophobic layer being advantageous, for example, for good contacting of a gas comprising CO2, while a hydrophilic layer can be advantageous for good contacting of an aqueous electrolyte .
  • GDEs are in particular electrodes in which liquid, solid and gaseous phases are present and where the conductive catalyst catalyzes the electrochemical reaction between the liquid and the gaseous phase.
  • Electro-osmosis is an electrodynamic phenomenon in which a force towards the cathode acts on particles in solution with a positive zeta potential and a force towards the anode on all particles with a negative zeta potential. If there is a conversion at the electrodes, ie if a galvanic current flows, there is also a material flow of the particles with positive zeta potential to the cathode, regardless of whether the species is involved in the conversion is divided or not. The same applies to a negative zeta potential and the anode. If the cathode is porous, the medium is also pumped through the electrode. One also speaks of an electro-osmotic pump.
  • the material flows caused by electro-osmosis can also flow in the opposite direction to concentration gradients. Diffusion-related currents that compensate for the concentration gradients can thus be overcompensated. For example, this may involve a flow of carbonate and / or hydrogen carbonate ions in the first electrolytic cell.
  • a separator is a barrier, for example a layer, which in an electrolysis cell has a spatial and at least partially also material separation between different spaces of the electrolysis cell, e.g. Anode compartment, electrolyte compartment, salt bridge compartment, cathode compartment, etc., as well as an electrical separation between anode and cathode, but allow ion transport between the different compartments.
  • a separator does not have a permanently assigned potential, like an electrode.
  • a separator can, for example, be a flat barrier with the same surface area.
  • membranes and diaphragms can be seen as special examples of separators.
  • the present invention relates to a method for producing CO from CO 2 comprising
  • the product comprising CO is also suitable for pressure build-up.
  • the product comprising CO according to certain embodiments, is also low in H2, because it can be produced in a separate container, a first reactor.
  • the educt comprising CO2 is not particularly limited and can be used, for example, as a gas mixture, which can also be moistened, for example, for better contacting of an electrode - here e.g. a first cathode, or solution.
  • a gas mixture which can also be moistened, for example, for better contacting of an electrode - here e.g. a first cathode, or solution.
  • the electrolytic conversion is also not particularly restricted, in particular the anode reaction is not particularly restricted and can be, for example, the conversion of water.
  • the first electrolytic cell is not particularly limited if it has a first cathode and a first anode.
  • the two electrodes, that is, the first cathode and the first anode, are not particularly limited.
  • the first cathode is a gas diffusion electrode.
  • an educt comprising CO2 is introduced into the electrolysis cell and reduced on the cathode side using the GDE, a liquid, preferably aqueous, electrolyte being able to be present on the other side.
  • the first anode is a gas diffusion electrode.
  • a mixture comprising formic acid and / or formate is formed in the electrolytic reaction, the mixture also being able to contain other components such as other products of the electrolytic reaction, but preferably in the reaction Settlement essentially results in formic acid and / or formate, preferably more than 50, 90, 95 or even 99% by weight, based on the CO2 that is converted.
  • a mixture comprising formic acid is formed.
  • a mixture of formate is formed. This can depend, for example, on an electrolyte in the electrolytic reaction.
  • This mixture comprising formic acid and / or formate is discharged from the first electrolytic cell in a suitable manner, which is not particularly limited, and can be carried out, for example, in cocurrent or countercurrent to supplying the starting material comprising CO2, for example via a suitable discharge device.
  • the mixture comprising formic acid if appropriate after passing through a container for intermediate storage, is introduced into a first reactor in which a product comprising CO is released from the mixture, the release being not restricted here and also dependent on it whether there is essentially formic acid or formate.
  • thermal energy is generated as an unusable energy loss in the electrolytic conversion of CO2 to CO in aqueous media.
  • the cell voltage is again rounded to 1.47 V.
  • FIG. 1 the first step of the C0 2 adsorption on a surface, here an exemplary metal M, is shown.
  • the first reduction in the electrochemical conversion which is shown in FIG. 2, then takes place in a step 2.
  • This is followed in a third step by a first protonation in aqueous media, which is shown in FIG. 3.
  • a step 4 which is shown in FIG. 4, a second reduction takes place, an output channel for format F (format type exit channel) also being possible, whereupon CO desorption or a further step occurs in a fifth step Reduction follows (not shown).
  • format F format type exit channel
  • the CO2 is absorbed on the surface of the metal M in the first step and an electron is transferred in step 2, which formally increases the oxidation number of the carbon by 1.
  • Metal carboxylates are basic and can be protonated relatively easily by water, which releases the first hydroxide ion in step 3.
  • step 4 This is followed by the second reduction stage in step 4, which creates a “structural isomer” of the formate.
  • the pseudoformate breaks down into a hydroxide ion and carbon monoxide, as shown in Figure 4.
  • Thermodynamic considerations are path independent i.e. in principle it is not important whether the energy is supplied in the form of electrical or thermal energy.
  • the usable energy share of the various forms of energy is significantly different. Electricity is a form of energy with 100% exergy. In the case of heat, the usable energy is limited by Carnot efficiencies.
  • thermodynamic considerations which is not particularly limited - here, for example, water oxidation - is the same for both process sequences.
  • the minimum cell voltage for the production of CO from CO2 is 2.04 V and then at least the neutralization energy in the cathode compartment is released again in the form of unwanted heat.
  • the reference point is always the total reaction CO2 - CO + h O2 with 1.47 V.
  • the carbon In carbon monoxide and formate / formic acid, the carbon has the same oxidation state of +2.
  • the anode reaction provides the necessary protons for the neutralization to formic acid in these considerations.
  • the minimum total tension in aqueous media is 1.60 V.
  • This energy can also be used, at least in part, from the waste heat of the electrolyzer for the CO release.
  • CCd adsorption step on a surface here an exemplary metal M
  • a protonation takes place in a third step from the acidic medium, which is shown in FIG. 7.
  • a fourth step which is shown in FIG. 8, a surface rearrangement takes place, which here enables an output channel for format F (format type exit channel), whereupon a thermal CO release can follow in a fifth step
  • format F format type exit channel
  • FIG. 9 shows the theoretical voltage of 1.47 V, which must be used for the gas phase conversion from CO2 to CO and which can come from renewable energy 1, for example.
  • the same voltage would also result from a direct conversion of CO2 to CO in acidic medium (half-cell voltage rounded at the anode in water electrolysis - 1.48 V, rounded at the cathode 0.02 V, so that rounded for the cell result in -1.47 V), which, however, has not been technically possible up to now due to the low hydrogen overvoltage on silver, for example.
  • FIG. 10 it is shown that, when implemented in a non-acidic environment, additional thermal energy 3 has to be used, which has to be additionally used as energy 2, for example renewable energy.
  • energy 2 for example renewable energy.
  • FIG. 11 shows the route via formic acid in basic form, a voltage of -0.12 V being recorded here for the cathode half-cell (formate formation) with the same anode half-cell.
  • thermal loss 5 which, when rounded, corresponds to a voltage of 0.13 V.
  • the C02 / HC03 / C03 2 / 0H balance is therefore the main problem for the energy-efficient use of renewable energy in the direct one-step electrochemical synthesis of CO2 to CO and / or to hydrocarbons.
  • the mixture comprising formic acid and / or formate is removed in solution, preferably in aqueous solution. This is possible, for example, when using an aqueous electrolyte, at least in the space between the first anode and the first cathode.
  • a less preferred embodiment of the invention is that in a, for example neutral, electrolyte (e.g. with KHCO3, K2SO4, etc.) a formate salt such as potassium formate on a suitable first cathode, e.g. an electrode containing Pb or Sn, and this is isolated by crystallization.
  • a formate salt such as potassium formate on a suitable first cathode, e.g. an electrode containing Pb or Sn, and this is isolated by crystallization.
  • the mixture comprising formic acid and / or formate essentially comprises a formate salt or even only a formate salt.
  • This can then be decomposed in the first reactor.
  • Decomposition of, for example, potassium formate takes place in the range around its melting point of 260-300 ° C. However, due to the high temperatures, this design is less preferred.
  • an acid which is not particularly restricted and which is added to the mixture comprising formic acid and / or formate in the first electrolytic cell and / or outside, for example in a container for intermediate storage and / or a first reactor can.
  • exemplary preferred acids are sulfuric acid and / or hydrochloric acid.
  • the formate obtained can be neutralized and decomposed by the acid, for example sulfuric acid.
  • Sulfuric acid is a preferred acid here because it is a common commodity product. If an electrolyte containing potassium salt is used, a potassium sulfate obtained can also be used as fertilizer and / or electrolyte additive.
  • a third possibility is to generate formic acid directly electrochemically, as described, for example, in "Electrochemical conversion of CO2 to formic acid utilizing Sustainion TM membranes", Hongzhou Yang, Jerry J. Kaczur, Syed Dawar Sajjad, Richard I. Masel, Journal of C0 2 Utilization 20 (2017) 208-217, which is referred to for the generation of formic acid. Of course, other electrochemical methods for generating formic acid are also possible.
  • Table 3 Electrical conductivity of formic acid at 25 ° C in a mixture with water
  • the concentration of formic acid in the mixture comprising formate and / or formic acid should not be too high, but also not too low, in order to ensure sufficient conversion.
  • the content of formic acid and / or formate in the mixture comprising formic acid and / or formate after the electrolytic reaction of the starting material comprising CO2 is in a range from 0.5% by weight or more and 100% by weight or less, preferably 1% by weight or more and 95% by weight or less, more preferably 5% by weight or more and 90% by weight or less.
  • non-volatile soluble additives for increasing the conductivity for example in the electrolyte, can also be added to the mixture comprising formic acid and / or formate. These can also support the decomposition to CO and H2O at the same time.
  • an aqueous electrolyte is present in the first electrolytic cell at least between the first cathode and the first anode.
  • a, preferably aqueous, first electrolyte for the electrolytic conversion of the starting material comprising CO2 to a mixture comprising formic acid and / or formate comprises an acid and / or a salt in order to increase the conductivity.
  • a, preferably aqueous, first electrolyte for the electrolytic conversion of the starting material comprising CO 2 to a mixture comprising formic acid and / or formate comprises an acid and / or a formate salt and / or a sulfate salt, more preferably a liquid acid, for example sulfuric acid .
  • salts as additives can make this possible, preferably formates and / or sulfates, e.g. preferably alkali formate, preferably potassium formate, or also alkali sulfate, e.g. Potassium sulfate.
  • alkali formate preferably potassium formate
  • alkali sulfate e.g. Potassium sulfate.
  • Adding sulfuric acid for example, can increase the conductivity above 100 mS / cm due to the availability of free protons.
  • the concentration of the acid in the electrolyte of the first electrolytic cell is set in a range from 0.01 to 50% by weight, for example 0.1 to 40% by weight, in particular 1 to 35% by weight.
  • a concentration of a salt in the electrolyte of the first electrolytic cell can likewise be set in a range from 0.01 to 50% by weight, for example 0.1 to 40% by weight, in particular 1 to 35% by weight.
  • a maximum concentration can also be up to and including 20% by weight, for example in order to enable a sufficient anode reaction.
  • An acid addition, in particular sulfuric acid addition, to the (first) electrolyte in the first electrolytic cell is possible in particular if an anion exchange membrane is present on the side of the first cathode, which additionally blocks the diffusion of protons, especially at higher current densities.
  • the anion exchange membrane is not particularly limited here and can be separate from the first cathode or bound as in a membrane electrode assembly (MEA).
  • At least one anion exchange membrane preferably in a region of the first cathode, is present between a first cathode and a first anode of the first electrolytic cell. This is particularly advantageous when using a basic electrolyte. Depending on the cathode used, it may not be present, for example if the formation of formate and / or formic acid is good at the first cathode, for example with a cathode comprising Pb.
  • the first electrolytic cell has at least no anion exchange membrane in a region of the cathode or even has no anion exchange membrane.
  • the first electrolytic cell has a cation exchange membrane or a bipolar membrane between a first cathode and a first anode in a region of the first anode.
  • the cation exchange membrane or the bipolar membrane are not particularly limited and can in turn be present separately or as an MEA together with the anode. In addition to controlling the ion transport, they can preferably prevent formate from migrating to the anode and being decomposed there.
  • a - first - cathode of the first electrolytic cell comprises or contains a metal which is selected from Cu, Bi, Pb, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenidic compounds, and / or alloys and / or mixtures thereof, preferably Pb, Bi, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenide compounds, and / or alloys and / or mixtures thereof, more preferably Pb, Bi, in particular Pb.
  • a metal which is selected from Cu, Bi, Pb, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenidic compounds, and / or alloys and / or mixtures thereof, preferably Pb, Bi, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenide compounds, and / or alloys and / or mixtures thereof, more preferably Pb, Bi
  • the first cathode consists of a metal which is selected from Cu, Bi, Pb, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenide compounds, and / or alloys and / or mixtures thereof, preferably Pb, Bi, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenide compounds, and / or alloys and / or mixtures thereof, more preferably Pb, Bi, in particular Pb.
  • the electrolytic conversion of the starting material comprising CO2 into a mixture comprising formic acid and / or formate can also take place at a practical cell voltage which is much lower than usual voltages when reducing CO2 to CO, for example at 2.5 2.7 V with common overvoltages.
  • the mixture comprising formic acid and / or formate is suitably removed from the first electrolytic cell, for example via a tube
  • the mixture comprising formic acid and / or formate Before the mixture comprising formic acid and / or formate is introduced into the first reactor, it can be temporarily stored in a first container, for example for storage, adjustment of a suitable concentration of formic acid and / or formate (eg by evaporation), etc.
  • a suitable concentration of formic acid and / or formate eg by evaporation
  • it can also be delivered to a further distant first reactor, so that a temporal and / or spatial separation between the first electrolysis cell and the first reactor is also possible.
  • the mixture comprising formic acid and / or formate is temporarily stored in a first container after it has been removed from the first electrolytic cell and before being introduced into the first reactor.
  • the mixture comprising formic acid and / or formate is not introduced directly into the first reactor, for example via a tube, a hose, a line and / or another suitable connecting device, the mixture comprising formic acid and / or formate can be suitably introduced into the first reactor, for example via a tube, a hose, a line and / or another suitable connecting device, the mixture comprising formic acid and / or formate can be suitably introduced into the first reactor, for example via a tube
  • the release of CO from formic acid and / or formate can then take place in a suitable manner, for example by setting a suitable temperature, acid concentration, and / or presence of a suitable catalyst, etc., the measures being not particularly limited and common measures can correspond to formic acid decomposition.
  • CO is released from the mixture comprising formic acid and / or formate in the first reactor by dehydration, preferably by heating and / or heterocatalytic Dehydration.
  • a suitable temperature is not particularly limited here and can also depend, for example, on the pressure and / or a catalyst, etc., and can for example comprise 10-130 K, preferably 10-80 K, above the electrolyte temperature and / or the mixture
  • Formic acid and / or formate, which is introduced into the first reactor are, for example, in a range from 70 ° C to 190 ° C, for example 70 ° C to 150 ° C.
  • Formic acid usually boils at normal pressure with decomposition at 101 ° C. The decomposition can also take place slowly at room temperature.
  • a solution of acid / formic acid is liquid, ie any pressure can actually be built up during decomposition. Pressures above 1 bar (1 * 10 5 Pa) are preferred, particularly preferred pressures between 30 bar (30 * 10 5 Pa) and 100 bar (100 * 10 5 Pa), as they occur in the chemical process industry, for example. This also saves compressors.
  • CO can also be efficiently converted into hydrocarbons in a basic electrolyte.
  • common anodes can also be used here, in contrast to the usual production of hydrocarbons in a single electrolytic cell.
  • the CO produced in the process according to the invention described above is thus further converted in a second electrolytic cell to at least one hydrocarbon, the reaction preferably taking place in the presence of a second, basic electrolyte.
  • the anode can include common metals such as Fe, Ni and / or NiFe, and the cathode material is not particularly limited either, as discussed further below.
  • a further aspect of the present invention relates to a process for the electrolytic conversion of a starting material comprising CO to a mixture comprising at least one hydrocarbon, the reaction taking place in the presence of a basic electrolyte, in particular anolyte, preferably with the anode Fe, Ni and / or NiFe.
  • a basic electrolyte in particular anolyte, preferably with the anode Fe, Ni and / or NiFe.
  • the material of the cathode is not particularly limited and can comprise any materials which enable CO conversion, for example a metal which is selected from Cu, Ag, Pd, Pt and / or Au, preferably Cu, and / or Alloys and / or compounds thereof, and / or mixtures thereof.
  • the C0 2 / HC0 3 / C0 3 2 / 0H equilibrium affects not only the reduction product CO, but all other reduction products such as ethylene, ethanol, propanol, acetate or the trace products allyl alcohol, ethylene glycol etc.
  • the electrolyte (anolyte and catholyte) as a whole can be strongly basic and e.g. a KOH solution in water can be chosen.
  • the basic electrolyte is not particularly limited.
  • CO can make sense to use CO from fossil sources (coal power gasifier, etc.) in order to then process it with renewable electricity, e.g. to produce ethylene, in order to obtain a partially green product.
  • CO can also originate from the decomposition of formic acid, which in turn is also accessible to CO 2 and H 2 by means of homogeneous catalysis.
  • the present invention relates to a device for producing CO from C0 2 comprehensively
  • a first electrolyte cell comprising a first cathode and a first anode for the electrolytic conversion of an educt comprising CO 2 to a mixture comprising formic acid and / or formate, which is designed to convert an educt comprising CO 2 to a mixture comprising formic acid and / or formate ;
  • a first feed device for an educt comprising C0 2 to the first electrolytic cell which is designed with the first electrolytic cell to supply an educt comprising C0 2 to the first cathode;
  • a first discharge device for a mixture comprising formic acid and / or formate which is connected to the first electrolytic cell in a region between the first cathode and the first anode and which is designed to form a To remove mixture comprising formic acid and / or formate from the first electrolytic cell;
  • a first reactor for releasing a product comprising CO from the mixture comprising formic acid and / or formate which is designed to release a product comprising CO from the mixture comprising formic acid and / or formate;
  • a second feed device for the mixture comprising formic acid and / or formate which is connected to the first reactor and is designed to supply the mixture comprising formic acid and / or formate to the first reactor;
  • a second discharge device for discharging the product comprising CO from the first reactor, which is designed to discharge the product comprising CO from the first reactor.
  • the method according to the invention for producing CO from CO 2 can be carried out.
  • certain aspects, which are described with regard to embodiments of the method according to the invention can also be used in the device according to the invention.
  • the first electrolytic cell is not particularly limited insofar as it comprises a first cathode and a first anode.
  • the material of the cathode is not particularly limited.
  • the first cathode of the first electrolysis cell comprises or contains a metal which is selected from Cu, Bi, Pb, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenidic compounds, and / or Alloys and / or mixtures thereof, preferably Pb, Bi, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenide compounds, and / or alloys and / or mixtures thereof, more preferably Pb, Bi, in particular Pb.
  • the first cathode consists of a metal which is selected from Cu, Bi, Pb, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenidic compounds, and / or alloys Stakes and / or mixtures thereof, preferably Pb, Bi, Hg, In, Sn, Cd, TI and / or compounds, in particular chalcogenidic compounds, and / or alloys and / or mixtures thereof, more preferably Pb, Bi, in particular Pb .
  • the first anode is not particularly limited and can be adapted to the anode reaction, and the anode material can also differ depending on whether a cation exchange membrane or a bipolar membrane is present or not.
  • the first feed device is not particularly limited and can be, for example, a pipe, a hose, a line, etc.
  • the first discharge device is not particularly limited and can be, for example, a pipe, a hose, a line, etc.
  • a further discharge device for unreacted educt comprising CO 2 and / or a further feed device for electrolyte and / or educt for the anode and / or further feed and / or discharge devices for the first electrolytic cell can also be present, which can also be used, for example, with other feed devices lines can be connected, for example if unreacted CO 2 is recycled.
  • the second feed device and the second discharge device are not particularly limited and can be, for example, a tube, a hose, a line, etc.
  • the second feed device may or may not be connected to the first discharge device and, for example, is not connected directly to it if a first container for the intermediate storage of the mixture comprising formic acid and / or formate is present.
  • the first reactor is also not particularly limited.
  • the first reactor comprises at least one heating device which is not particularly is limited to favor thermal decomposition of formic acid, for example at least one heat pump to use the heat from the electrolysis. If the electrolyte is returned, appropriate heat exchangers can also be provided.
  • the first electrolytic cell has at least one anion exchange membrane between the first anode and the first cathode, preferably in a region of the first cathode. It can be designed as an MEA or separately from the cathode.
  • the first electrolytic cell has a cation exchange membrane or a bipolar membrane between the first cathode and the first anode in a region of the first anode.
  • a cation exchange membrane or a bipolar membrane between the first cathode and the first anode in a region of the first anode.
  • These can also be provided as MEAs or separately.
  • the first cathode of the first electrolytic cell comprises a metal which is selected from Cu, Bi, Pb, Hg, In, Sn, Cd, TI and / or alloys and / or mixtures thereof, preferably Pb, Bi, Hg, In , Sn, Cd, TI and / or alloys and / or mixtures thereof, further preferably Pb, Bi, in particular Pb.
  • the device according to the invention further comprises a first container for intermediate storage of the mixture comprising formic acid and / or formate, which is arranged between the first discharge device and the first supply device and which is designed to comprise the mixture comprising formic acid and / or Caching formate.
  • the first container is not particularly limited. It can comprise a third discharge device, which is designed to discharge the mixture comprising formic acid and / or formate after the intermediate storage. The third discharge device may or may not be connected to the second feed device.
  • the first container can also have further discharge devices, for example for unreacted CO2 and / or decay products of formic acid and / or water, which can be evaporated to concentrate formic acid and / or formate.
  • the first container can also comprise at least one heating device.
  • FIG. 1 An exemplary method according to the invention and an exemplary device according to the invention are shown schematically in FIG.
  • the formic acid is produced electrochemically in the first electrolytic cell 10 on the first cathode 11, with water being electrolyzed as the electrolyte on the first anode 12.
  • At the first anode 12 there is a cation exchange membrane, and at the first cathode 11 an anion exchange membrane AEM.
  • the starting material comprising CO2 is supplied via the first feed device 13, and the mixture comprising formic acid is fed via the first discharge device by means of the line 14 to a first container 20.
  • an outlet for oxygen is provided on the anode side.
  • the mixture comprising formic acid is temporarily stored, which preferably serves at the same time for the separation of further gas such as excess CO2 or the by-products H 2 or CH 4 .
  • This vessel can, but does not have to, serve as an electrolyte reservoir and / or formic acid store. Electrolyte can, for example, be returned via line 15 to the first electrolytic cell 10, and likewise not converted CO2 via line 16.
  • the process chain can also be spatially and temporally separated at this point.
  • the formic acid content can be, for example, between 1 and 100%, and can be adjusted to a preferred limit in the range of 5 to 90% in the course of the electrolysis.
  • pure CO is then released in the second process step in the first reactor 30 by dehydrating the formic acid, as a result of which the formic acid content drops again.
  • the decomposition is achieved, for example, by heating or heterocatalytic dehydration, which are not shown in detail.
  • non-decomposed formic acid can be returned to the first container 20.
  • a suitable temperature of, for example, 60 ° C. can be set for storage, the electrolyte here also being able to be buffered if necessary.
  • the temperature can then be raised to a suitable temperature of, for example, 10 to 80 K above the electrolyte temperature and / or compression can take place in order to facilitate the release of CO.
  • a suitable temperature for example, 10 to 80 K above the electrolyte temperature and / or compression can take place in order to facilitate the release of CO.
  • a suitable temperature for example, 10 to 80 K above the electrolyte temperature and / or compression can take place in order to facilitate the release of CO.
  • a suitable catalyst low CO 2 or even CO 2 free CO can be obtained.
  • the structure corresponds to that of Example 1, with a bipolar membrane being used instead of a CEM.
  • the structure corresponds to that of Example 1, but there is no AEM on the cathode side and in particular a Pb-containing cathode is used.
  • the overvoltage on lead electrodes for hydrogen is very high, so that it may also be possible to work in acidic electrolytes (see also Example 5).
  • lead electrodes provide formate in CCh electrolysis. The local pH of the electrode becomes more basic the higher the current density at which it is operated, i.e. it is expected that the formate yield will be even higher at higher current densities than at lower ones.
  • Example 1 water with a salt such as KSO is used instead of water as electrolyte.
  • Example 1 water with an acid such as sulfuric acid is used as the electrolyte instead of water.
  • the AEM can also be dispensed with, in particular if the first cathode comprises 11 Pb. It is advantageous here that the Pb has a high overvoltage over hydrogen of -0.71 V.
  • FIGS. 14 and 15 were suitably adjusted by weighing.
  • Figure 16 the initial mixtures were adjusted by weighing, after which sulfuric acid was added Weighing gradually added.
  • the conductivity was determined using a conventional conductivity sensor.
  • the mixtures and the water were mixed with sulfuric acid and the mass fraction of sulfuric acid in% by weight in relation to the mixtures was plotted on the x-axis.
  • FIGS. 14 to 16 show that by adding salt or acid, the poor conductivity of formic acid - a possible intermediate in the present process for the production of CO - can be increased, so that it can also assume technically relevant values.
  • CO2 can be reduced electrochemically to CO in one step.
  • hydroxide ions formed with excess CO2 form hydrogen carbonate.
  • This reaction is the cause of an energy (better exergy) loss of the invested electrical energy.
  • 28% of the electrical energy used is converted into heat.
  • This loss can be synergistically reduced to approx. 16% (280 mV) by combining an electrochemical and a thermochemical step.
  • thermochemical for example acid catalyzed
  • the electrolyte volume simultaneously represents a storage volume for formic acid or CO.
  • Acid or salt-like additives increase both the conductivity and they are control variables for the thermal release of the CO.

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  • Electrochemistry (AREA)
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  • Metallurgy (AREA)
  • Inorganic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Abstract

L'invention concerne un procédé de fabrication de CO à partir de CO2, ainsi qu'un dispositif pour la mise en œuvre du procédé.
PCT/EP2019/085669 2019-01-30 2019-12-17 Procédé de fabrication de co à bon rendement énergétique Ceased WO2020156734A1 (fr)

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CN114768724B (zh) * 2022-04-19 2023-08-22 福建福豆新材料有限公司 一种高纯一氧化碳用甲酸裂解装置
EP4435150A1 (fr) * 2023-03-21 2024-09-25 Nederlandse Organisatie voor toegepast-natuurwetenschappelijk Onderzoek TNO Electrolyse du co2 dans une cellule electrochimique a trois compartiments comprenant un milieu de fermentation
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