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
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/10—Preparation of carboxylic acids or their salts, halides or anhydrides by reaction with 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
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
  • C25B1/01—Products
  • C25B1/02—Hydrogen or oxygen
• • 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
  • C25B1/01—Products
  • C25B1/23—Carbon monoxide or syngas
• • 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
  • C25B9/05—Pressure cells
• • 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
  • C25B9/70—Assemblies comprising two or more cells
• • 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

Definitions

• the present invention concerns an apparatus for production of high purity carbon monoxide, CO, based on electrolysis of carbon dioxide, C02 in combination with a high purity C02 feedstock and gas cleaning operation at temperatures above -100°C.
• Solid Oxide Electrolysis Cells, SOEC are used for the electrolysing.
• the proposed invention relates to the production of CO of high purity where the purification relies on simple, low cost purification techniques that do not involve cryogenic tech ⁇ niques .
• the product gas (CO + H2) is then purified to high purity CO (typically > 99%) in different steps, for instance including a final cryogenic state to separate H2 from the CO and to re ⁇ move possible impurities of N2 and Ar .
• an object of the present invention to provide an SOEC apparatus and method to produce CO at a lower cost than the presently known techniques. It is a further object of the present invention to provide an SOEC apparatus and method to produce CO at a low cost and at a high purity without the use of cryogenic techniques.
• the invention relates to a CO production and purification method which is based on C02 electrolysis in combination with simple and in-expensive 'room temperature' gas cleaning and gas separation methods.
• This invention makes it technically and economically feasible to produce high purity CO in small quantities, for example at the consumption site or at local distribution centres.
• C02 electrolysis is less known than water electrolysis as fewer techniques are available for C02 electrolysis.
• One technology which is very efficient for C02 electrolysis is Solid Oxide Electrolysis Cells.
• the principle of the C02 electrolyser is that C02 (possibly including some CO) is fed to the electrolyser cathode. As current is applied, the C02 is converted to CO to provide an output stream with a high concentration of CO.
• the output will be con ⁇ verted CO and unconverted C02. If needed, the unconverted C02 can be removed in a C0/C02 separator operating at tempera- tures above -100°C to produce the final high purity CO.
• an embodiment of this invention includes: ⁇ The use of high purity C02 as feedstock for the electro ⁇ lyser
• Solvent absorption involves a cyclical process in which C02 or CO is absorbed from a gas stream directed into a liquid, typically water or an amine. Typically, C02 is removed and the processed gas stream is then the final purified CO stream. The absorbent liquid can be processed to remove the C02, which can then be re-used for further electrolysis. The resulting C02-free liquid is used again for absorption and the process continues. This technique is fairly widely used in a range of applications, but it needs a large amount of power to regenerate the solvent. Adsorption is based on a cyclical process in which C02 or CO is adsorbed from a gas stream on to the surface of a solid, typically a mineral zeolite.
• PSA pressure swing adsorbers
• Membranes made of polymers or ceramics can be used to effec ⁇ tively sieve out C02 or CO from gas streams.
• the membrane ma ⁇ terial is specifically designed to preferentially separate the molecules in the mixture.
• a range of configurations ex- ists either simply as gas separation devices or incorporating liquid absorption stages. This process has not yet been ap ⁇ plied on a large scale and there are challenges related to the composition and temperature of the input gases. Further ⁇ more, the selectivity of the membranes is limited and many recycles will typically be needed to obtain high purity (e.g > 99.5%) gas output.
• Condensation techniques use low temperatures to cool and con ⁇ dense the C02 from the electrolyser gas streams. Using two coolers where C02 is condensed at one (e.g. at -90°C) and C02 is released from the other (e.g. at -40 C) would allow con- tinuous operation of a condensating C02 removal unit.
• this invention has a dedicated electro ⁇ lyser design which is used to remove the necessary amount of C02 from the CO + C02 stream.
• the current which can be applied to all cells in the stack is limited by the flow across the one cell with the minimum flow, such that the maximum current corresponds to a 100% conversion in the cell with minimum flow. If current is applied which would correspond to a conversion rate above 100% for this minimum flow cell, the current would introduce structural changes in the minimum flow cell and the cell would deteriorate quickly together with the stack. Typically this leads to maximum conversion rates of 80% for 70-cell stacks and 90% for 10-cell stacks.
• the C02 separator can be of any known art as well as a further SOEC as will be disclosed in the following.
• the separated C02 can be recycled to the input side of the SOEC electrolyser .
• a scheme which allows SOEC stacks to operate with very high conversion rates to directly produce CO output stream of very high puri- ty (e.g. larger than 90% and e.g. larger than 99%) .
• This em ⁇ bodiment is based on the individual control of the current across each cell based on monitoring of the voltage across each cell.
• the voltage across an SOEC cell can be expressed as: where I C eii and R ce ii are the current and resistivity of the relevant cell, respectively.
• p C o2 Pco and p 0 2 are the partial pressures (in bar) of C02, CO and 02 respectively.
• an SOEC stack is used for direct production of high purity CO. This is done by monitor ⁇ ing the voltage across each cell and individually adjusting the current across each cell to give a desired cell voltage corresponding to a desired level of C02.
• This current adjustment scheme can be realised in many ways. This could be by providing a relatively large common current and then removing surplus current with a diode or more flexi ⁇ bly with a transistor and a transistor current controlling circuit. A more energy efficient alternative would be to pro ⁇ vide a relatively low common current and then add additional current (e.g. based on switch mode technology) to obtain the desired cell voltage.
• additional current e.g. based on switch mode technology
• the 15% C02 and 85% CO is con- verted to high purity CO e.g. 99.7% CO and 0.3% C02 in a stack where current is controlled individually for the dif ⁇ ferent cells or cell groups.
• This embodiment is cost effec ⁇ tive as it provides a relative low cost, traditional SOEC stack for the bulk of the C02 conversion and the relative more expensive individual voltage and current control SOEC stack for a small part of the conversion.
• the main source of such potential impurities is leakages in the SOEC stack. This can be leakages between the cathode and the anode side of the stack and it can be leakages between the stack and the external atmosphere as indicated in fig.5. These types of leakage are often experienced in Solid Oxide stacks. Leakages are caused partly by imperfect sealings be- tween cells and interconnects and partly because small cracks in solid oxide cell electrolytes may easily exist after pro ⁇ duction or may evolve during the system lifetime. If the electrolyser operates with pure oxygen on the anode side, leakages between the anode and the cathode side will not affect the purity of the produced gas (defined as C02 concentration + CO concentration) as oxygen will combust with CO to form C02) .
• the oxygen side (the an ⁇ ode) is flushed with C02 to reduce the oxygen concentration without reducing the C02 + CO purity of the SOEC output gas- ses even if the SOEC stack is subject to internal leakage.
• the SOEC stack or stacks are enclosed in a closed compartment which is flushed with C02. This implies that the C02 + CO pu ⁇ rity of the SOEC output gasses are maintained even if the SOEC stack is subject to external leakage.
• Compartment P0 can further be purged with CO 2 where the purge stream after addition of air is passed through a catalytic oxidation step, see Figure 6.
• the catalytic oxidation step should comprise a catalyst active in the oxidation reaction between CO and 0 2 .
• the catalyst could for example be a noble metal catalyst such as Pt and/or Pd optionally combined with V 2 O 5 and WO 3 on an alumina or T1O 2 based carrier.
• the catalyst should operate above 100 C, preferably between 150 and 250 C to assure elim ⁇ ination of CO emitted to the local environment.
• the absolute pressure in compartment denoted P0 can be chosen to be set below atmospheric pressure to assure that CO leaking into P0 cannot escape to the surroundings un ⁇ der any circumstances. Improving the purity of the SOEC input gas
• the polluting gas may affect the operation of or even poison the SOEC or the CO/C02 separation equipment •
• the polluting gases will in general be separated into the C02 stream. As it is typically advantageous to recycle this stream to the SOEC, the polluting gases may build up in the system
• Adsorbents or absorbants are used before the SOEC to re- move undesired gas contaminations.
• sulphur species and solixanes are known to poison Solid Oxide cells. These can be absorbed for example with active carbon or Ni- or Cu-based absorbers.
• a x purge' can be build into the recycle stream to avoid the accumulation of polluting gases.
• the recycle stream will typically include CO which in most cases can not be vented safely.
• One embodiment of this inven ⁇ tion includes a purge outlet of the recycle stream which is combined with oxygen from either air or the oxygen output of the SOEC and where the CO and excess 02 forms
• CO + CO -> C + C02 Deposition of carbon is thermodynamically advantageous in temperature regions below roughly 700°C and as the CO rich gas cools down carbon may be deposited on for example metal surfaces of pipes or heat exchangers. This may corrode the metal through the mechanism known as metal dusting which eventually may destroy the subjected metal parts.
• Carbon deposition and metal dusting can be avoided in CO rich environments by using special metals or special coatings of the subjected surfaces.
• selected metals or coatings are used to avoid carbon formation and metal dusting at the output section of the SOEC electrolyser .
• This embodiment includes the use of Ni-rich metals such as Inconel or specifically Inconel 693.
• This embodiment also in ⁇ cludes special coatings of metal surfaces such as surfaces coated with Cu or Sn/Ni coatings for example with 55-65% Sn.
• a dual tube arrangement In addition to the coatings mentioned, another possibility is to use a dual tube arrangement.
• a viable option is to insert a copper tube inside a tube with the re ⁇ quired mechanical strength. Copper tubes loose their mechanical strength at elevated temperatures but by applying a cup ⁇ per tube inside a for example a high alloy stainless steel tube and assuring intimate contact between the tube surfaces the mechanical strength of the steel tube can be combined with the resistance towards metal dusting of the copper tube. The protection towards metal dusting is due to that the ma ⁇ jority of the gas is exposed to the Cu surface.
• a device for production of CO with a purity above 90% when the device is provided with C02 with a purity above 90% said device comprising at least one Solid Oxide Electrolysis Cell with an anode side and a cathode side and said device further comprises an output gas separation unit, wherein the device is operating at temperatures between 0°C - 50°C, pref ⁇ erably at 10°C - 40°, preferably at room temperature.
• a device comprising a plurality of Solid Oxide Electrolysis Cells arranged in a stack, and wherein said device further comprises means for individual control of the current across selected Solid Oxide Electrolysis Cells.
• a device wherein said individual control of the current is based on monitoring the voltage across selected Solid Oxide Electrolysis Cells.
• the output gas separation unit comprises a plurality of cells arranged in a gas separation Solid Oxide Electrolysis Cell stack, and wherein said stack comprises means for individual control of the current across selected cells.
• the device further comprises means to flush the anode side of the at least one Solid Oxide Electrolysis Cell with C02.
• the device comprises a compartment enclosing the at least one Solid Oxide Electrolysis Cell, and wherein said compartment comprises means to flush the space enclosed by the compartment .
• a device wherein the pressure of the cathode side is higher than the pressure of the anode side, the pressure of the anode side is higher than the pres ⁇ sure of the compartment and the pressure of the compartment is below ambient pressure and wherein the compartment is flushed with CO 2 and the CO 2 purge is directed from the com ⁇ partment to a catalytic oxidation reactor utilizing a cata ⁇ lyst comprising a noble metal catalyst such as Pt and or Pd optionally combined with V 2 O 5 and WO 3 on an alumina or T1O 2 based carrier and the catalyst operates above 100°C, prefera ⁇ bly between 150°C and 250°C.
• a cata ⁇ lyst comprising a noble metal catalyst such as Pt and or Pd optionally combined with V 2 O 5 and WO 3 on an alumina or T1O 2 based carrier and the catalyst operates above 100°C, prefera ⁇ bly between 150°C and 250°C.
• a device wherein said output gas separation unit is one of, a wa- ter/amine wash, a Pressure Swing Adsorption or selective mem ⁇ branes .
• said output gas separation unit is one of, a wa- ter/amine wash, a Pressure Swing Adsorption or selective mem ⁇ branes .
• a device comprising a plurality of stacked Solid Oxide Electrolysis Cells and a plurality of stacks, wherein said stacks are connected in networking connection.
• a device wherein selected components which are subject to metal dust ⁇ ing are made of Ni-rich metals such as Inconel, preferably Inconel 693, or said components are coated with Cu or Sn/Ni coatings, preferably 55-65% Sn.
• a device wherein selected components which are subject to metal dust ⁇ ing are made of double tubes; an inner tube which is a copper tube which is placed inside an outer tube with higher mechanical strength than the copper tube, thereby achieving metal dusting protection and simultaneously combining the mechanical strength of the outer tube with the resistance towards metal dusting of the copper tube.
• a process for production of high purity CO comprising the steps of
• ⁇ providing said second gas to the output gas separation unit • operating said gas separation unit at temperatures be ⁇ tween 0°C - 50°C, preferably at 10°C - 40°, preferably at room temperature and thereby producing a third output gas comprising CO with a purity above 90%.
• a process according to claim 13 or 14 further comprising the step of
• a process according to any of the claims 13-15 further comprising a compartment enclosing the at least one Solid Ox ⁇ ide Electrolysis Cell and further comprising the step of
• a process according to claim 16 further comprising the step of
• Fig. 7 shows a schematic diagram of one possible embodiment of the invention.
• High purity C02 is flushed to both the x fuel' and x oxygen' side of an SOEC stack.
• the input C02 on the fuel side passes two heat exchangers, while only a single heat exchanger is used on the input side of the x oxygen' side.
• the reason for this asymmet- ric configuration is that oxygen passes from the fuel to the oxygen side and that the heat capacity therefore is highest on the fuel in and oxygen out streams. This is also reflected in the temperatures and duties of the different heat exchang ⁇ ers as shown in fig. 7.
• the heat exchanger at the SOEC fuel side is made of either Ni- rich metals such as Inconel, particularly Inconel 693 or coated metal parts e.g. Sn/Ni coated parts.
• the output temperatures of the heat exchangers closest to the stacks are 675°C and 750°C on the fuel and oxygen side respectively.
• the SOEC stack is assumed to be operated at the thermo neutral operation point at a temperature of 800 °C. Consequently, the input C02 streams are heated to 800°C in two electrical heaters.
• a simple variation of this configuration would be to use one electrical heater at the fuel input, heat the stream here to approximately 825°C and let the heat exchanging capacity of the SOEC stack heat up the oxygen side input.
• the SOEC stack has a capacity to pro ⁇ cute approximately 1.2 Nm3/h CO. This could for example be realised with stacks based on 50 cells with an effective area of 10 x 10 cm. These cells could operate at a current density of the order of 0.75 A/Cm2, a cell voltage of 1.25 V and an effective SOEC conversion efficiency of 3.1 kWh/Nm3.
• the SOEC cells could be based on a Ni/YSZ support layer, a Ni/YSZ fuel-side electrode a YSZ electrolyte and an LSM elec ⁇ trode on the Oxygen side.
• the C02 input streams here are chosen to be around 2 Nm3/h at both fuel and oxygen side. This gives a fairly moderate CO concentration of only 63% at the output. This is chosen to allow for a non-uniform flow distribution in the stacks, but much higher output concentrations are possible by using for example individual cell current control.
• the 2 Nm3/h input flow to the Oxygen side is chosen to assure an 02 concentration well below 50% at the output. This reduc ⁇ es the speed of corrosion on the oxygen side output and sim ⁇ plifies the choice of materials for heat exchangers and pip- ing .
• the gas stream is cooled and the ma ⁇ jority of the CO is being removed in a separator, which for example could be based on membranes.
• the remaining C02 is in this example just send into the air but could also be recy ⁇ cled (including some possible fraction of CO) into the fuel side input.
• a fraction of the SOEC out ⁇ put is recycled to the input, where the residual CO may also help to avoid oxidation at the input of the fuel side of the SOEC stack.
• Fig. 8 shows an example of stack networking.
• the lower stack is made up by 20 cells, the upper one by 10 cells.
• the bottom of both stacks is in this case facing the internal manifold plate .
• Fig. 9 shows the importance of actively handling the possible impurities introduced in the output stream of an SOEC system by stack leakages.
• Test 1 shows the impurities (N2 and 02) of a stack operating with uniform pressure and with air used for flushing the oxygen side.
• C02 was used instead of air to flush the oxygen side and in this case the impurity level have been reduced from roughly 1.5 mole% to less than 0.75 mole%.
• the pressure of the fuel side (the cathode) has been increased to be roughly 100 mbar higher than on the oxygen side and in the external stack compartment.
• C02 was used for flushing the oxygen side.
• the impurity level was below 0.3 mole% which is sufficient for meeting for exam- pie the standard industrial grade for bottled CO.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Inorganic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Carbon And Carbon Compounds (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

Priority Applications (10)

Applications Claiming Priority (2)

Publications (2)

Family

ID=47843255

Family Applications (1)

Country Status (14)

Cited By (40)

Families Citing this family (31)

Family Cites Families (12)

• 2013
  • 2013-02-19 TW TW102105706A patent/TWI500820B/zh active
  • 2013-02-26 CA CA2866312A patent/CA2866312C/en active Active
  • 2013-02-26 ES ES13708114T patent/ES2877849T3/es active Active
  • 2013-02-26 DK DK13708114.7T patent/DK2823087T3/da active
  • 2013-02-26 KR KR1020147026422A patent/KR102080571B1/ko active Active
  • 2013-02-26 US US14/382,948 patent/US9284651B2/en active Active
  • 2013-02-26 EA EA201491624A patent/EA201491624A1/ru unknown
  • 2013-02-26 EP EP13708114.7A patent/EP2823087B1/en active Active
  • 2013-02-26 WO PCT/EP2013/053780 patent/WO2013131778A2/en not_active Ceased
  • 2013-02-26 AU AU2013229699A patent/AU2013229699B2/en active Active
  • 2013-02-26 JP JP2014560305A patent/JP6192669B2/ja active Active
  • 2013-02-26 CN CN201380013115.8A patent/CN104220645B/zh active Active
  • 2013-03-04 AR ARP130100686A patent/AR090224A1/es unknown
• 2014
  • 2014-09-04 CL CL2014002343A patent/CL2014002343A1/es unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events