Classifications

• • 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
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
• • 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
  • C25B15/02—Process control or regulation
• • 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

Definitions

• the invention relates to an arrangement for the carbon dioxide electrolysis according to the preamble of claim 1.
• C02 carbon dioxide
• the carbon dioxide is converted with the supply of electrical energy in a higher energy product such as CO, CH4, C2H4 or C 1 -C 4 alcohols.
• the electrical ⁇ cal energy in turn is preferably derived from renewable energy sources such as wind power or photovoltaics.
• C02 For the electrolysis of C02 usually metals are used as catalysts Kata ⁇ .
• the type of metal influences the products of electrolysis.
• C02 is, for example, of Ag, Au, Zn, and with limitations of Pd, Ga, almost from ⁇ finally reduced to CO, while copper is a variety of hydrocarbons as reducing products to be ⁇ obachten.
• metal alloys are also gen as well as mixtures of metal and metal oxide which is catalytically effective co-, of interest because they may increase the Selekti ⁇ tivity of a specific hydrocarbon.
• a gas diffusion electrode (GDE) are used as the cathode, similar to the chlor-alkali electrolysis to Zvi ⁇ rule the liquid electrolyte, the gaseous C02 and the solid silver particles to produce a three-phase boundary.
• GDE gas diffusion electrode
• an elec- rolysezelle is, as known also from the fuel cell technology used with two electrolyte compartments, the Elect ⁇ rolythuntn are separated by an ion exchange membrane.
• the working electrode is a porous gas diffusion electrode. It comprises a metal net onto which a mixture of PTFE,
• Activated carbon, a catalyst and other components is applied. It includes a pore system into which the
• the counter electrode is a sheet applied with platinum or an iridium mixed oxide.
• the GDE is in contact with the electrolyte on one side. On the other hand, it is supplied with C02, which is forced through the GDE with overpressure (so-called convective mode of operation).
• the GDE can while holding various metals and metal compounds ent ⁇ that have a catalytic effect on the process.
• the functioning of a GDE is known, for example, from EP 297377 A2, EP 2444526 A2 and EP 2410079 A2.
• the resulting product is gaseous and not liquid at the Koh ⁇ dioxide electrolysis. Furthermore, the CO 2 used forms salts with the alkali metal or alkaline earth metal hydroxide formed from the electrolyte.
• Cheswei ⁇ se is formed with the use of potassium salts as the electrolyte KOH and there are the salts of KHC03 and K2C03. by virtue of The operating conditions lead to a crystallization of the salts in and on the GDE from the gas side.
• a stable long-term operation of the gas diffusion electrode in the range of more than 1000 h is not possible in the C02 electrolysis, since the resulting salt clogs the pores of the GDE and thus this gas-impermeable. It is an object of the present invention to provide an improved arrangement for the carbon dioxide electrolysis, with a stable long-term operation while avoiding the aforementioned disadvantages is made possible.
• the arrangement according to the invention for the carbon dioxide electrolysis comprises an electrolytic cell having an anode and a cathode, said anode and cathode are connected to a voltage ⁇ supply, wherein the cathode is designed as Gasdiffusi ⁇ onselektrode to which on a first side of a gas space and a second side of a cathode chamber connects, a subsequent to the electrolysis cell Elect ⁇ rolyt circuit and a gas supply for supplying carbon-lendioxid condominiumm gas into the gas space. Furthermore, the gas space has an outlet for electrolyte,
• Carbon dioxide and product gases of the electrolysis and off ⁇ lass is ver ⁇ connected via a throttle with the electrolyte circuit, wherein the throttle is designed to cause a definable pressure difference between the gas space and the cathode space at a flow of a mixture of product gases and liquid electrolyte.
• the embodiment can be combined according to claim 1 with the features of one of the subclaims or preferably also with those of several subclaims. Accordingly, the following features can additionally be provided for the arrangement:
• the throttle can be inserted at an angle of between 0 ° and
• the throttle comprises a vertical pipe.
• the tube preferably has a length of between 60 cm and 140 cm, in particular between 90 cm and 110 cm.
• the tube can be arranged rotatably. This allows you to change the absolute height that bridges the pipe. Since ⁇ by turn, caused the pipe pressure difference is changed. Thus, therefore, a desired pressure difference between gas space and cathode space can be achieved by a rotation of the
• Adjust tube The maximum pressure difference exists when the pipe is vertical.
• the tube has an inner diameter which corresponds to at least twice the inner diameter of the other connection between the gas space and the electrolyte circuit.
• Insbesonde ⁇ re is the inner diameter of five times the inner diameter of the other compound.
• the inner diameter is preferably less than ten times the inner diameter of the other compound.
• the length provides for the amount of hydrostatic pressure
• the outlet is preferably in the gas space on the bottom angeord ⁇ net.
• the outlet can be connected via a return connection to the gas supply.
• the outlet is conveniently connected to an overflow tank.
• the outlet and a possibly subsequent pipe carry electrolyte and carbon dioxide and product gases.
• electrolyte and carbon dioxide and product gases For the further work of the electrolytic cell gases and electrolyte must be shared ⁇ , which happens by the introduction into the overflow tank.
• the electrolyte collects and in the area above the electrolyte, the carbon dioxide and, if necessary, product gases.
• Appropriately includes the gearver ⁇ bond to the gas supply in the upper region of the overflow container, so that the carbon dioxide can be recycled without electrolyte.
• the leadership of electrolyte to the overflow tank is preferably gravity driven.
• the overflow tank can be constructed separately from the gas space and connected for example via a pipe connection.
• the overflow tank can also be integrated in the gas space.
• the overflow container can be connected to the electrolyte circuit via a throttle, wherein the throttle is configured, a definable pressure difference between the gas space and the effecting method space.
• the pressure difference should not be dependent on whether gas, electrolyte or a mixture thereof passes through the throttle. As a result, the pressure difference is kept within a predetermined range. Thereby a continuous flow of electrolyte through the gas diffusion electric ⁇ en is maintained in the gas space, which prevents salinization, on the other hand be ⁇ adjoins the flow of the electrolyte to prevent the cover of the gas diffusion electrode with a liquid film which rolyse the efficiency of the elec- would reduce.
• the throttle may be arranged, for example, at a medium height in the overflow container. As soon as the liquid level reaches this mitt ⁇ sized height in the overflow container the electrolyte is transported through the choke from ⁇ . The liquid level in the overflow tank is thus kept constant at the middle level.
• a first pressure sensor may be present in the gas space. This is a pressure signal, for example, to a control ⁇ device for controlling the shut-off device.
• a second pressure sensor can be arranged in the cathode compartment. This can also give a pressure signal to the controller. From the two pressure signals, the controller can determine the pressure difference.
• a differential pressure sensor for gas space and cathode space may be present. This directly gives a signal for the pressure difference to a control device.
• the pressure difference between the gas space and the cathode space is preferably maintained between 10 and 100 hPa. This light one
• Turbulence promoters may include, for example: flow channel, flow breaker, reduction of the cross section.
• the turbulence promoters may be designed so that an air gap of between 0.1 mm and 5 mm remains between them and the surface of the cathode. This advantageously ensures that the turbulence promoters are not wetted by the electrolyte passing through the gas diffusion electrode and held there. This in turn would lead to a reduced flow of carbon dioxide and severely damage the overall efficiency of the electrolysis .
• the air gap creates a distance of the turbulence promoters from the surface of the gas diffusion electrode, so that the electrolyte can drain and collect on the bottom side in the gas space.
• the turbulence promoters may have flow channels, by means of which the electrolyte is guided to the edge of the gas space.
• the volume flow of the pump is significantly greater than the feed gas volume flow, ie the volume flow of new Carbon dioxide.
• a Besse ⁇ rer removal of the overflow from the headspace is due to the higher gas flow rate.
• the pump device may be arranged in the gas space.
• the pumping device can be arranged at the entrance to the gas space into which the gas feed opens or in the region of the outlet.
• the pump device may be, for example, a diaphragm pump, which is advantageously resistant to chemicals.
• Other pump types are also possible, such as gear, piston, stroke or peristaltic pumps.
• the volume flow of the pumping device can be, for example, 2 l / min to 5 l / min. He should be at least the Zehnfa ⁇ che the flow rate of the incoming carbon dioxide.
• the pumping device may alternatively be arranged in the return connection. In other words, the pumping device is arranged outside the gas space.
• the construction of an electrolysis cell 11, shown schematically in Figure 1 is typically adapted to carry out a carbon dioxide ⁇ electrolysis.
• the off ⁇ guide shape of the electrolytic cell 11 comprises at least one anode 13 with adjoining anode compartment 12 and a cathode 15 and ei ⁇ NEN adjacent the cathode compartment 14 and anode compartment 12 cathode chamber 14 are separated by a membrane 21st
• the membrane 21 is typically made of a PTFE-based material.
• a construction without membrane 21 is also conceivable in which a pH compensation then exceeds that of the membrane 21.
• Anode 13 and cathode 15 are electrically connected to a voltage ⁇ supply 22, which is controlled by the control unit 23.
• the control unit 23 can apply a protective voltage or an operating voltage to the electrodes 13, 15, that is to say the anode 13 and the cathode 15.
• the anode compartment 12 of the electrolysis cell 11 shown is equipped with an electrolyte inlet.
• the illustrated Ano ⁇ denraum 12 includes an outlet for electrolyte and, for example, oxygen O 2 or other gaseous by-product, which is gebil ⁇ det in the carbon dioxide electrolysis at the anode 13.
• the cathode compartment 14 likewise has at least one product and electrolyte outlet in each case. In this case, the total electrolysis product can be composed of a large number of electrolysis products.
• the electrolytic cell 11 is also designed in a three-chamber structure, in which the carbon dioxide CO 2 is flowed via the designed as a gas diffusion electrode cathode 15 in the Katho- denraum 14.
• Gas diffusion electrodes make it possible a solid catalyst, a liquid electrolyte and a gaseous Elektrolyseedukt in contact to bring MITEI ⁇ Nander.
• the catalyst can be made porous and take over the electrode function, or a porous electrode takes over the catalyst function.
• the pore system of the electrode is designed so that the liquid and the gaseous phase can equally penetrate into the pore system and can simultaneously present therein or at its electrically accessible surface.
• An example of a gas diffusion electrode is an oxygen-consuming electrode used in chloralkali electrolysis.
• a gas diffusion electrode comprising the Ka Thode 15 in this example, a metal mesh on which a Mi ⁇ research made of PTFE, activated carbon and a catalyst is applied.
• a metal mesh on which a Mi ⁇ research made of PTFE, activated carbon and a catalyst is applied.
• the electrolytic cell 11 comprises a The carbon dioxide reaches in the gas space 16, the cathode 15 and there can penetrate into the porous structure of the cathode 15 and thus come to the reaction.
• the arrangement 10 comprises an electrolyte circuit 20, via which the anode space 12 and the cathode space 14 are supplied with a liquid electrolyte, for example K 2 SO 4, KHCO 3, KOH, Cs 2 SO 4, and the electrolyte is returned to a reservoir 19.
• a liquid electrolyte for example K 2 SO 4, KHCO 3, KOH, Cs 2 SO 4, and the electrolyte is returned to a reservoir 19.
• the circulation of the electrolyte in the electrolyte ⁇ rolyt Vietnameselauf 20 is carried out by an electrolyte pump 18th
• the gas space 16 in the present example comprises an outlet 25, which is arranged in the bottom area.
• the outlet 25 is designed as an opening with a sufficient cross section, so that both electrolyte, which passes through the cathode 15, as well as carbon dioxide and product gases can pass through the outlet in the ⁇ bound pipe.
• the outlet 25 leads to an overflow vessel 26.
• the liquid in the overflow vessel 26 the liquid
• a pump 27 in this embodiment a diaphragm pump, and further to the gas supply 17.
• the pump 27 may also be a piston, lift, extruder or gear pump.
• a portion of the gas supply 17, the gas space 16, the tube 18 and the overflow vessel 26 together with its connection to the outlet 25 thus together form a circuit.
• the carbon dioxide and pre ⁇ existing product gases are guided by the overflow vessel 26 back into the Gaszu ⁇ management and thus partially guided the gas in a circle.
• the volume flow of the pump 27 is significantly higher than the volume flow of new carbon dioxide.
• Feed gas which is not consumed is thereby guided past advantageously again at the cathode 15, and has to be reduced once more or several times re ⁇ the opportunity. product gases are partly also led in a circle. By passing the carbon dioxide past the cathode 15 several times, the efficiency of the conversion is increased. From the overflow vessel 26 there is a further connection, which leads back to the electrolyte circuit 20.
• This compound begins with an outlet 29 which is disposed on a side wall of the Kochlaufge ⁇ fäßes 26, preferably near the bottom, but not in the ground.
• the outlet 29 is connected to a throttle 30, which is designed as a vertical piece of pipe with a length of example ⁇ 90 cm.
• the diameter of the pipe section is significantly greater than that of the leads to the throttle 30.
• the supply line has for example an inner ⁇ diameter of 4mm, the pipe section has an inner diameter of 20mm.
• the throttle 30 is the output side, ie at the top
• the differential pressure of the reactor can be continuously lowered 30 to almost zero in horizontal ⁇ right position.
• the cathode 15 is "pumped" in the direction of the gas space 16. es ent ⁇ are on the side of the gas chamber 16 drops on the Oberflä ⁇ surface of the cathode 15, which coalesce and collect in the form of the bottom of the cathode 15th
• the accumulating electrolyte thereby causes a

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• Chemical & Material Sciences (AREA)
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• Metallurgy (AREA)
• Automation & Control Theory (AREA)
• Inorganic Chemistry (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Electrodes For Compound Or Non-Metal Manufacture (AREA)

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• 2016
  • 2016-06-30 DE DE102016211824.2A patent/DE102016211824A1/de not_active Withdrawn
• 2017
  • 2017-05-18 BR BR112018075707-1A patent/BR112018075707A2/pt not_active IP Right Cessation
  • 2017-05-18 US US16/312,203 patent/US20190233957A1/en not_active Abandoned
  • 2017-05-18 ES ES17724054T patent/ES2795698T3/es active Active
  • 2017-05-18 CN CN201780040306.1A patent/CN109415821A/zh active Pending
  • 2017-05-18 DK DK17724054.6T patent/DK3445893T3/da active
  • 2017-05-18 AU AU2017288319A patent/AU2017288319B2/en not_active Ceased
  • 2017-05-18 EP EP17724054.6A patent/EP3445893B1/de active Active
  • 2017-05-18 PL PL17724054T patent/PL3445893T3/pl unknown
  • 2017-05-18 WO PCT/EP2017/061924 patent/WO2018001636A1/de unknown
• 2018
  • 2018-12-20 CL CL2018003721A patent/CL2018003721A1/es unknown

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