OPTIMIZING CARBON MONOXIDE PRODUCTION FROMHETEROGENEOUS FEEDSTOCK

Abstract

It is provided a process for increasing production of carbon monoxide (CO) and recycling carbon dioxide when treating synthesis gas using a carbon dioxide-to-carbon monoxide conversion unit, such as a Reverse Water Gas Shift (RWGS) reactor, converting excess CO.sub.2 from the produced syngas to additional CO, using an external source of green, renewable or low carbon intensity hydrogen.

Claims

1. A process for increasing production of carbon monoxide (CO) and recycling carbon dioxide when treating synthesis gas comprising the steps of: passing a first synthesis gas stream comprising hydrogen, carbon monoxide and carbon dioxide through a first separation zone, thereby separating said first synthesis gas stream into a second stream comprising hydrogen and carbon monoxide, and a third stream comprising carbon dioxide; feeding said third stream to a carbon dioxide-to-carbon monoxide conversion unit, producing a fourth stream comprising carbon monoxide, and a fifth stream comprising oxygen; mixing said second stream and the fourth stream producing a syngas product stream; and feeding the syngas product stream into a product synthesis unit.

2. The process of claim 1, further comprising combining said third stream with a hydrogen stream generating a fourth stream comprising carbon dioxide and hydrogen; feeding said fourth stream into the carbon dioxide-to-carbon monoxide conversion unit consisting of a Reverse Water Gas Shift (RWGS) reactor to produce a fifth stream comprising carbon monoxide, hydrogen and unreacted carbon dioxide; passing said fifth stream to a second separation zone for removing the unreacted carbon dioxide and producing a CO.sub.2 depleted syngas stream, wherein the unreacted carbon dioxide is recycled back into the third stream for combining with the hydrogen stream and feeding into the RWGS reactor; and combining the H.sub.2 and CO from the second stream and H.sub.2 and CO from the CO.sub.2 depleted syngas stream producing a syngas product stream.

3. The process of claim 2, where the second separation zone is combined with the first separation zone, wherein the fifth stream RWGS reactor product is recycle back into the first separation zone, recovering in-situ the CO.sub.2 from the fifth and first streams and producing the third stream comprising carbon dioxide from both streams.

4. The process of claim 3, wherein the H.sub.2 and CO from the fifth stream is combined within the first separation zone with the H.sub.2 and CO from the first stream, producing the second stream comprising hydrogen and carbon monoxide producing the syngas product stream which is fed into the product synthesis unit.

5. The process of claim 2, further comprising mixing the syngas product stream with additional hydrogen for adjusting the stochiometric ratio requirement of the product synthesis unit.

6. The process of claim 1, where the product synthesis unit is a Fischer Tropsch reactor.

7. The process of claim 2, where said first and second separation zone comprises a CO.sub.2 selective solvent, a CO.sub.2 adsorption step and a solvent regeneration step to produce the desired carbon dioxide streams.

8. (canceled)

9. The process of claim 2, wherein all or a portion of said hydrogen stream is used as a stripping gas to extract CO.sub.2 from the CO.sub.2 selective solvent in the first separation zone including hydrogen in the third stream, comprising carbon dioxide, and reducing the amount of said hydrogen to generate the fourth stream.

10. The process of claim 2, wherein all or a portion of said hydrogen stream is used as a stripping gas to extract CO.sub.2 from the CO.sub.2 selective solvent in the second separation zone thus generating unreacted carbon dioxide RWGS stream and additional hydrogen.

11. (canceled)

12. (canceled)

13. (canceled)

14. The process of claim 1, where the carbon dioxide-to-carbon monoxide conversion unit is a CO.sub.2 electrolysis unit or a CO.sub.2+H2O co-electrolysis unit.

15. The process of claim 2, wherein the RWGS reactor is a heated catalytic multitube reactor design, an autothermal catalytic reactor, a fixed bed adiabatic catalytic reactor, or a combination thereof.

16. (canceled)

17. The process of claim 2, wherein the RWGS reactor is a high temperature autothermal POX type reactor, with no catalyst.

18. The process of claim 1, where said first synthesis gas stream is produced from partial oxidation, gasification and/or reforming of a carbonaceous feedstocks.

19. The process of claim 18, wherein the carbonaceous material comprises a plastic, a metal, an inorganic salt, an organic compound, industrial wastes, recycling facilities rejects, automobile fluff, municipal solid waste, ICI waste, C&D waste, refuse derived fuel (RDF), solid recovered fuel, sewage sludge, used electrical transmission pole, railroad ties, wood, tire, synthetic textile, carpet, synthetic rubber, materials of fossil fuel origin, expended polystyrene, poly-film floc, construction wood material, or any combination thereof.

20. (canceled)

21. (canceled)

22. The process of claim 1, further comprising admixing to the third stream an external input of CO.sub.2 or CO.sub.2 input obtained from a process effluent, increasing the CO.sub.2 flow rate upstream of the CO.sub.2 to CO conversion unit thereby, increasing the flow rate of CO in the syngas product stream, or further comprising admixing to the third stream a reformed low carbon intensity (CI) carbon rich stream, increasing the carbon content upstream of the CO.sub.2 to CO conversion unit thereby, increasing the flow rate of CO in the syngas product stream.

23. (canceled)

24. The process of claim 23, where the carbon rich stream is a waste gas or liquid from the product synthesis unit; or the carbon rich stream is a gas or liquid from an external source.

25. (canceled)

26. The process of claim 23, where the carbon rich stream is reformed or partially oxidized at high temperature upstream of the RWGS unit producing additional syngas, and wherein the hot reformed waste stream is mixed at the inlet of the RWGS unit to provide all or part of the heat required for the endothermic RWGS reactor, reducing the energy requirement of the process.

27. The process of claim 26, wherein the carbon rich stream is reformed at more than 900? ? C. upstream of the RWGS unit

28. The process of claim 26, where the reforming step is conducted in a reforming unit.

29. (canceled)

30. A process for increasing production of carbon monoxide (CO) and recycling carbon dioxide when treating synthesis gas comprising the steps of: a. gasifying a carbonaceous material in a fluidized bed, producing a classified crude syngas; b. reforming said classified crude syngas at a temperature above mineral melting point, producing reformed synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide; c. passing said reformed synthesis gas through a first separation zone, thereby separating said first synthesis gas stream into a second stream comprising hydrogen and carbon monoxide, and a third stream comprising carbon dioxide; and d. recycling said third stream comprising carbon dioxide to said fluidized bed gasifier, with or without steam and/or O.sub.2 to reduce said reformed synthesis gas H.sub.2/CO ratio, and increasing the total CO yield and production.

31-48. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Reference will now be made to the accompanying drawings.

[0057] FIG. 1 illustrates a schematic representation of the process integrating RWGS steps in accordance to an embodiment.

[0058] FIG. 2 illustrates a schematic representation of an alternative process comprising one single CO.sub.2 separation zone in accordance to an embodiment.

[0059] FIG. 3 illustrates a schematic representation of an alternative process wherein the recovered CO.sub.2 and/or the waste gas and/or waste liquid can be recycled at the gasification and reforming step in accordance to an embodiment.

[0060] It will be noted that throughout the appended drawings, like features are identified by like reference numerals.

DETAILED DESCRIPTION

[0061] In accordance with the present disclosure, there is provided a process for increasing production of carbon monoxide (CO) and recycling carbon dioxide when treating synthesis gas using a carbon dioxide-to-carbon monoxide conversion unit.

[0062] It is provided a mean to optimize the amount of carbon recycling of waste materials by minimizing the amount of CO.sub.2 required for inertizing and pressurizing feedstock, isolate a CO.sub.2 rich stream, and convert the CO.sub.2 rich stream into CO to further synthesize FT products. As encompassed herein, any hydrocarbon waste streams can be converted into additional syngas which will further increase the amount of CO available, which will further increase the carbon recycling.

[0063] It is provided a method for maximizing yield of CO derived from partial oxidation, gasification and/or reforming carbonaceous feedstock with the integration of a Reverse Water Gas Shift (RWGS) unit, or alternative CO.sub.2 conversion to CO unit, to convert excess CO.sub.2 from the produced syngas to additional CO, when an external source of green, renewable or low carbon intensity hydrogen is available.

[0064] Several carbonaceous solid, liquid or gas feedstock partial oxidation, gasification and/or reforming end up generating a crude syngas streams with an H.sub.2/CO ratio lower then 2.0, which is required per stoichiometry for the production of methanol, other alcohol and/or hydrocarbons (i.e. Fischer Tropsch). The H.sub.2/CO ratio generated from these processes are often below 1.5 and even as low as 0.7 and below. In partial oxidation, gasification and/or reforming processes, in addition to H.sub.2 and CO, CO.sub.2 is always produced and it will be present at various concentration in the crude syngas depending on the process efficiency and feedstock heating value.

[0065] In coal or liquid fossil fuel gasification and/or reforming plants producing a crude syngas with an H.sub.2/CO lower than that required per the ratio derived from the stoichiometric reactions of the desired end product, a water gas shift reactor is typically included in the plant design to shift a portion of the excess CO into additional H.sub.2 to rebalance the overall plant H.sub.2/CO ratio (per reaction 5 above), or alternatively, in situ shifted to additional H.sub.2 in the desired project syngas synthesis reactor, for example, with Fe-based Fischer Tropsch). Since the overall plant has an excess of CO.sub.2, a process unit is required for CO.sub.2 removal. Since those feedstocks also typically contain sulfur which are converted into reduced sulfur species (H.sub.2S, COS, etc.) in the gasification and/or reforming units, such typical plant also contains an acid gas removal (AGR) unit that removes both CO.sub.2 and sulfur reduced species. Reduced sulfur species are poisons for several syngas conversion catalysts and are also undesired in most final chemical and/or biofuel products.

[0066] In biomass rich or waste gasification and/or reforming valorization plant, such approach has the negative impact of losing valuable biogenic carbon via the carbon monoxide shift, which does not end-up in the final biogenic product, but rather as excess CO.sub.2 that the plant has to either valorized as very low value merchant CO.sub.2 and/or safely release it to atmosphere after treatment and increase the greenhouse gas impact of the plant.

[0067] It has been documented that rather than shifting excess CO to H.sub.2 in such a plant using biobased carbonaceous feedstock, an external source of hydrogen could be imported into the plant and combined with the plant rich CO bio-syngas to rebalance the overall plant H.sub.2/CO ratio to that required for the stoichiometric reactions of the desired end product.

[0068] It is also known that some chemicals and biofuel can be produced from the reaction of H.sub.2 and CO, but also from H.sub.2 and CO.sub.2. One such product is methanol, but also Fischer Tropsch using iron based catalyst and ethanol using micro-organism bio-catalyst. However, other type of synthesis catalyst does not offer this ability, including Co-based Fischer Tropsch catalyst as explained before. Similarly, in the chemical industry, acetic acid is produced from the carbonylation of methanol and CO, and cannot be directly produced from CO.sub.2.

[0069] Accordingly, it is provided a mean to maximize overall carbon feedstock conversion to the final desired chemical or fuel, for example, without being limited to, using Co-based catalyst Fischer Tropsch production from biomass, biomass rich waste and/or waste plastic gasification and/or reforming.

[0070] As seen in FIG. 1, a syngas stream (1) is provided with an H.sub.2/CO ratio lower than 2 and with excess CO.sub.2 as produced by most carbonaceous feedstock gasification and/or reforming process.

[0071] An external input of hydrogen (4) is provided from an external source (i.e. not generated from the same syngas generation unit) in quantity and ratio sufficient to fully convert the desired amount of excess CO.sub.2 to additional CO (per reaction 2).

[0072] The CO.sub.2 rich syngas (1) is sent to a first CO.sub.2 separation zone (2) to produce a CO.sub.2 depleted syngas (H.sub.2+CO rich) (9) and a rich CO.sub.2 stream (3). This said rich CO.sub.2 stream (3) is then mixed with a portion of or the entire external hydrogen stream (H.sub.2 import #1) (4), and then feed to a RWGS unit (5) to convert the CO.sub.2 to CO, thus producing a new syngas stream (6). The RWGS reactor effluent is first cooled to condense and separate the water generated by the RWGS reaction and then fed to a second CO.sub.2 separation zone (7) to remove and recycle unconverted CO.sub.2 (13) to the RWGS unit (5). As an alternative, portions of the H.sub.2 import (4 and/or 4) can be feed to the first and/or second CO.sub.2 separation zone (2) and (7) for use as stripping gas when using a solvent based CO.sub.2 removal unit as described below. It is encompassed that external CO.sub.2 or CO.sub.2 input from another process effluent (14) can be mixed with the CO.sub.2 rich stream (3) upstream of the RWGS unit (5) to further increase the production of CO. The flow of the external source of hydrogen (4) must be increased accordingly.

[0073] As encompassed herein, the CO.sub.2 separation zone comprises a solvent based scrubbing system with a solvent selective for carbon dioxide absorption or CO.sub.2 selective solvent; a CO.sub.2 absorption step and a solvent regeneration step to produce the desired carbon dioxide streams. In an embodiment, the CO.sub.2 selective solvent is e.g., but not limited to, methanol, ethanol, N-Methyl-2-pyrrolidone (NMP), amine, propylene carbonate, dimethyl ether of polyethylene glycol (DMPEG), methyl isopropyl ether of polyethylene glycol (MPEG), tributyl phosphate, or sulfolane. Alternatively to a solvent based CO.sub.2 separation zone, the first and second separation zone described herein can also comprise a membrane unit which is permeable to carbon dioxide and retains hydrogen and/or carbon monoxide. Other alternative CO.sub.2 separation zone, but not limited to, may include a solid adsorbent system for selective adsorbtion of CO.sub.2 and/or CO with pressure or thermal swing technique.

[0074] The new CO.sub.2 depleted syngas stream or syngas product (8) from the RWGS and CO.sub.2 separation zone is then combined with the above CO.sub.2 depleted syngas (9) to be fed to the desired product synthesis unit (12), such as e.g. but not limited to a Fischer Tropsch reactor. If required, the balance of the external hydrogen import ((H.sub.2 import #2) (10) is combined to both CO.sub.2 depleted syngas stream to rebalance the overall plant H.sub.2/CO ratio to that required per the ratio derived from the stoichiometric reactions of the desired end product, which as exemplified herein is a Fischer Tropsch product produced from reaction 4.

[0075] The product synthesis unit (12) converts the H.sub.2 adjusted CO.sub.2 depleted syngas (11) into the final product (15). It is encompassed that waste gas and/or waste liquid (16) from the product synthesis unit can be recycled through a reforming unit such as an autothermal catalytic reactor (e.g. ATR) or a high temperature autothermal POX type reactor (non-catalytic) (17), or dry reforming reactor, but not limited to (see FIG. 2). The hot (e.g. >900? C.) reformed waste stream (18) can be mixed at the inlet of the RWGS unit (5) to provide all or part of the heat required for the endothermic RWGS reactor, and thus reducing the energy requirement of the entire process. It is also encompassed that waste gas and/or waste liquid can be recycled at the gasification and reforming step (19) (as shown in FIG. 3). This allows recycling of the carbon from the waste stream (16) thereby increasing the production of CO and improve the overall efficiency. A portion of the waste stream (16) can be purged to avoid accumulation of inert gases. It is also encompassed that the waste stream (16) can be used as fuel (16) in the RWGS unit (5), for example in a RWGS reactor feed pre-heater (fired type). Alternatively, an energy source of low carbon intensity (i.e. GHG emission) such as renewable fuel and/or renewable electricity can be used to provide heat in the RWGS unit.

[0076] In an embodiment, the RWGS reactor encompassed herein is an externally heated catalytic multitube reactor design, an autothermal catalytic reactor (ATR type with oxygen injection to further increase the feed temperature prior to the adiabatic RWGS reactor catalyst bed) or a fixed bed adiabatic catalytic reactor, or any combinations thereof. The catalyst in the RWGS reactor can be a nickel or an iron based catalyst, but not limited to. It is also encompassed that the RWGS reactor described herein may also be a high temperature autothermal POX type reactor, with oxygen injection similar to the ATR type, but with no catalyst.

[0077] It is also encompassed that the external source of hydrogen can be produced from a renewable source and/or low carbon intensity (i.e. GHG emission), including but not limited to water electrolysis with renewable power, biogas reforming or steam reforming, or low carbon intensity (CI) blue hydrogen (fossil fuel methane reforming with CO.sub.2 capture), low CI waste H.sub.2, etc.

[0078] As encompassed herein, the syngas stream originate from gasification of a carbonaceous material. The carbonaceous materials encompassed herein can be biomass-rich materials which may be gasified as described in International application no. PCT/CA2020/050464, the content of which is incorporated by reference in its entirety, and include, but are not limited to, homogeneous biomass-rich materials, non-homogeneous biomass-rich materials, heterogeneous biomass-rich materials, and urban biomass. The carbonaceous material can also be plastic rich residues or any waste/product/gas/liquid/solid that include carbon. It may also be any type of coal and derivative such as pet coke, petroleum product & by-product, waste oil, oily fuel, hydrocarbon and tar.

[0079] Homogeneous biomass-rich materials are biomass-rich materials which come from a single source. Such materials include, but are not limited to, materials from coniferous trees or deciduous trees of a single species, agricultural materials from a plant of a single species, such as hay, corn, or wheat, or for example, primary sludge from wood pulp, and wood chips. It may also be materials from refined single source like waste cooking oil, lychee fruit bark, etc.

[0080] Non-homogeneous biomass-rich materials in general are materials which are obtained from plants of more than one species. Such materials include, but are not limited to, forest residues from mixed species, and tree residues from mixed species obtained from debarking operations or sawmill operations.

[0081] Heterogeneous biomass-rich materials in general are materials that include biomass and non-biomass materials such as plastics, metals, and/or contaminants such as sulfur, halogens, or non-biomass nitrogen contained in compounds such as inorganic salts or organic compounds. Examples of such heterogeneous biomass-rich materials include, but are not limited to, industrial wastes, recycling facilities rejects, automobile fluff and waste, urban biomass such as municipal solid waste, such as refuse derived fuel (RDF), solid recovered fuel, sewage sludge, tire, synthetic textile, carpet, synthetic rubber, expended polystyrene, poly-film floc, used wood utility poles and wood railroad ties, which may be treated with creosote, pentachlorophenol, or copper chromium arsenate, and wood from construction and demolition operations which may contain one of the above chemicals as well as paints and resins.

[0082] As encompassed herein, the syngas stream which originate from gasification of a carbonaceous material, also require additional conditioning and treatment to become suitable for the product synthesis unit.

[0083] As described above, an AGR unit and a guard bed filter are utilized upstream of the product synthesis unit in order to reach very low contaminant level in the syngas. The AGR unit also has the ability to remove a portion of the CO.sub.2 from the sour syngas and generates a non-flammable CO.sub.2 stream suitable for pressurization and inertization of the carbonaceous feedstock at the gasification step but also for other purges requiring an inert gas.

[0084] Up-stream of the AGR, also as described in International application no. PCT/CA2020/050464, the gasification plant may also include a feeding system to feed the carbonaceous material into a fluidized bed gasifier, thus producing a crude syngas which is then thermally reformed at temperature above the carbonaceous material ashes (mineral) melting point, thus producing the reformed syngas (synthetic gas). In an embodiment, the fluidizing agent is air, oxygen, carbon dioxide, nitrogen, steam or any combination in any proportion thereof. The gasification plant may also include hot reformer syngas quench cooling and heat recovery, and include additional cleaning stages including particle removal, ammonia removal, chlorine removal, other catalyst poison removal via for example wet water scrubbers.

[0085] In an embodiment, carbonaceous materials can be fed as low density fluff RDF by a feeding system, lowering the costs of the pre-treatment of the feedstock by only partially pre-treating the RDF fluff. In another embodiment, carbonaceous materials can be a mixture of low density fluff having a particle size ranging from a few millimeters to many centimeters. In a non-limiting embodiment, carbonaceous materials can be in high density pelletized form with or without low density fluff. In another non limiting embodiment, carbonaceous materials can be a solid, liquid, gas or any composition in any proportion thereof that contain the carbon atom. In all cases the non-flammable CO.sub.2 stream extracted from the AGR can be used as low cost inert gas for pressurization and inertization of the carbonaceous feedstock at the gasification step. The uses of CO.sub.2 as inertization gas, not only remove O.sub.2 trapped in the bulk carbonaceous material feedstock to make it safe for injection in the gasifier, but also remove trapped N.sub.2 which would reduce the downstream syngas partial pressure in the product synthesis unit, and thus increase inert and non-condensable gases purge rate and losses of valuable syngas, and resulting in lower desired product yield.

[0086] In an embodiment, as seen in FIG. 3, the additional AGR extracted CO.sub.2 (3) can be recycled to the fluid bed gasifier (19) to be used as a fluidization agent and/or in combination with steam (20) and/or oxygen (21) to allow to adjust and optimize the reformed syngas H.sub.2/CO ratio. In another non limiting embodiment, such CO.sub.2 fluidization agent can be another CO.sub.2 sources extracted from the plant, and/or an external CO.sub.2 sources (14). Higher CO.sub.2 to steam ratio in the gasifier fluid bed allow to maximize CO yield and thus FT product yield. It is encompassed that these steps can be used with and without the combination of the current RWGS integration described herein.

[0087] The ratio or flow rate of H.sub.2 import #1 (4) depends on the amount of excess CO.sub.2 to be converted to CO and to achieve high efficiency in the RWGS unit. A distinguishing feature of the process provided herewith is to take advantage of the additional total H.sub.2 import required at the plant, which also include the H.sub.2 required to convert the CO load from the original syngas stream (1). Thus, this new integrated process takes advantage of this additional importation of H.sub.2 to use it, at least partially, in the RWGS unit to optimize the CO.sub.2 single pass conversion and reduce the size, CAPEX and energy consumption related to the CO.sub.2 removal and recycle steps, and eliminate the need for an H.sub.2 separation steps, which further reduce CAPEX and energy consumption.

[0088] Table 1 below shows an example of the split between H.sub.2 import #1 (4) and #2 (10), syngas stream at different CO.sub.2 level. For simplicity, an H.sub.2/CO ratio of 1 have been fixed for all cases and on the basis of 100 kmol/h of syngas, and assuming 100% CO.sub.2 removal and recycle (although in practice up to about 95% would apply).

TABLE-US-00001 TABLE 1 RWGS integration CO production increase 30% + Stream % v CO.sub.2 10% 15% 25% 30% external CO.sub.2 1 % v CO.sub.2 10% 15% 25% 30% 50% % v CO 45% 42.5% 37.5% 35% 25% % v H.sub.2 45% 42.5% 37.5% 35% 25% Syngas reference 100 100 100 100 100 flow rate (kmol/h) CO.sub.2 - kmol/hr 10 15 25 30 30 CO - kmol/hr 45 42.5 37.5 35 35 H.sub.2 - kmol/hr 45 42.5 37.5 35 35 14 External CO.sub.2 0 0 0 0 40 import Total available 10 15 25 30 70 CO.sub.2 to RWGS Extra CO 10 15 25 30 70 production from RWGS (kmol/h) 4 H.sub.2 import #1 20 30 50 60 140 (kmol/hr).sup.a 10 H.sub.2 import #2 55 57.5 62.5 65 105 (kmol/h).sup.a Total H.sub.2 Import 75 87.5 112.5 125 245 (kmol/h) 11 Total CO plant 55 57.5 62.5 65 105 production (kmol/h) % increase CO 122% 135% 167% 186% 300% production.sup.b 16 FT product yield 122% 135% 167% 186% 300% increase.sup.b .sup.aTotal H.sub.2 based on desired H.sub.2/CO ratio of 2.0 fed in the final syngas stream fed to the downstream syngas conversion unit to the desired end product. The split between H.sub.2 import #1 and #2, depends on the extent of single pass CO2 conversion to CO in the RWGS, which is turn depends on the H.sub.2/CO.sub.2 ratio feed to the RWGS unit and reactor operating temperature. For the purpose of demonstrating this invention, a high temperature RWGS have been used. .sup.b% increase CO production is Total CO plant production (kmol/h)divided by CO in Reference fed syngas (kmol/h). FT product yield increase is proportional to CO production increase.

[0089] Alternatively, the first and second CO.sub.2 separation zone can be combined into one single CO.sub.2 separation zone (FIG. 2), which further reduce the CAPEX of this novel design. Another alternative can be the combination of the first and/or second CO.sub.2 separation zone with the AGR, followed by guard bed filters on the CO.sub.2 stream (3) and CO.sub.2 depleted syngas stream (9) to remove trace contaminants in both streams.

[0090] In a further embodiment, other CO.sub.2 to CO conversion technology could be integrated such as for example CO.sub.2 electrolysis to CO and O.sub.2 or CO.sub.2+H.sub.2O co-electrolysis to H.sub.2+CO and O.sub.2, as presented before (equation 6 and 7). In case of CO.sub.2 electrolysis, the import of H.sub.2 #1 (4) would be zero, and all the total H.sub.2 import would be fed via the H.sub.2 Import #2 (10). In case of CO.sub.2+H.sub.2O co-electrolysis, the import of H.sub.2 #1 (4) would also be zero, and the total H.sub.2 import fed via H.sub.2 import #2 (10) would be reduced by the amount of H.sub.2 generated by the co-electrolysis step.

[0091] Several different methods can be used for the CO.sub.2 separation steps. It can be CO.sub.2 selective membrane separation technology, for example Polaris from MTR or PIX from Air Liquid. It can be an amine CO.sub.2 solvent process with a CO.sub.2 adsorption steps and a CO.sub.2 recovery steps from the solvent regeneration. In a preferred alternative, chilled methanol is used as a solvent. In a further preferred alternative, a simple chilled methanol pressure swing CO.sub.2 absorption/desorption can be implemented, and using the import #1 hydrogen (stream 4 and/or 4) as a CO.sub.2 stripping gas which further reduce the energy consumption requirement of the CO.sub.2 removal steps.

[0092] While the present disclosure has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations and including such departures from the present disclosure as come within known or customary practice within the art to and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.