Optimizing carbon monoxide production from heterogeneous feedstocks.

Abstract

Within the present disclosure, there is provided a method for increasing carbon monoxide (CO) production and recycling carbon dioxide during the processing of syngas using a carbon dioxide to carbon monoxide conversion unit, such as a reverse water gas shift (RWGS) reactor, where an external source of green hydrogen, renewable hydrogen, or low carbon intensity hydrogen is used to convert excess CO2 from the generated syngas into additional CO.

Description

[Technical field]

[0001] A method is disclosed for increasing carbon monoxide (CO) production and recycling carbon dioxide while balancing carbon dioxide requirements when processing synthesis gas using a carbon dioxide to carbon monoxide conversion unit. [Background technology]

[0002] As industrial demand for carbon recycling (circular economy) increases, there is great interest in using carbonaceous materials such as biomass, waste, or plastics in the production of syngas. Such syngas can be further utilized for the production of alcohol, liquid fuels, and many other chemicals. It is well known in the art that the production of syngas from solid, liquid, or gaseous carbonaceous feedstocks using conventional processes such as partial oxidation, gasification, and / or reforming produces mainly H2, CO, and CO2 in various concentrations. The ratios of H2 / CO and CO / CO2 vary depending on the process, its efficiency, and feedstock characteristics.

[0003] Very few synthesis gas conversion catalysts are capable of achieving very high carbon recycling through the reactions of both CO and CO. For example, methanol catalysts can achieve high carbon efficiency and also have the ability to convert CO+H to methanol. CO+2H2⇔CH3OH (1) CO2+H2⇔CO+H2O (2) (reverse WGS) CO2+3H2⇔CH3OH+H2O (3)

[0004] The integration of methanol syngas conversion technology with biomass-to-syngas, waste-to-syngas, or plastic-to-syngas production technologies allows achieving very high carbon recycling through the conversion of both CO and CO2 with an external source of hydrogen. This is particularly interesting when green or low carbon intensity H2 is available for integration into the biorefinery.

[0005] In many synthesis gas conversion catalysts and processes, CO2 is not converted to the final product, and in the worst case, CO2 is produced via the water-gas shift (WGS) reaction (equation (5)) or other side reactions. For example, it is well known in the art that currently commercially available cobalt (Co)-based Fischer-Tropsch (FT) catalysts cannot produce FT liquids / paraffins / waxes, etc. directly from CO2 and H2, i.e., their stoichiometry is based on the chemistry of CO+H2 (according to equation 4). CO+2H2→CH2-+H2O (4)

[0006] Most mature industrial-scale FT technology providers use Co-based FT catalysts.

[0007] On the other hand, iron (Fe)-based FT catalysts have good WGS activity (Eq. 5) to shift excess CO to excess H along with HO, thus rebalancing the syngas H / CO ratio to the required FT ratio of 2 (according to Eq. 5). However, there is limited data available on CO+H feed to Fe-based FT catalysts to produce FT products. Industrial scale applications are not yet available. CO+H2O⇔CO2+H2(5)(WGS)

[0008] Therefore, a cobalt-based FT biorefinery should separately manage the possibility of converting excess CO2 to CO along with H2 to feed the FT reactor. This needs to be achieved via Reverse Water Gas Shift (RWGS) as shown in Equation 2 above, or other techniques to convert CO2 to CO. One such alternative technology is the electrolysis of CO2 to CO and O2, or the co-electrolysis of CO2+H2O to H2+CO and O2 according to the following reactions:

number

[0009] RWGS is not currently carried out in industry at full scale (or only to a limited extent). High temperatures (>600°C to >900°C) are required to obtain equilibrium favoring the CO direction. One of the main challenges is also to obtain a catalyst that is active for the RWGS reaction but not for the methanation reaction (below). CO+3H2→CH4+H2O (8) CO2+4H2→CH4+2H2O (9)

[0010] The thermodynamic equilibrium of the methanation reaction is favored at lower temperatures and higher pressures. Thus, RWGS operation at higher temperatures offers the added benefit of thermodynamically limiting the extent of the methanation reaction and the resulting reactant losses, but also offers additional challenges to achieve an energy-efficient process at such temperatures. R&D work and efforts have been put into developing RWGS catalysts that do not limit the methanation selectivity at lower temperatures (e.g., 500-600 °C), but they are not yet available on a commercial scale and have not been demonstrated for long-term stability and performance. Lower RWGS reaction temperatures help in terms of thermal efficiency, but single-pass CO2 conversion is lower, which entails higher CO2 and / or H2 recycle ratios and larger separation units, and therefore higher energy and electricity consumption.

[0011] In gasification processes, the synthesis gas is generally composed of H2, CO, and CO2. The CO2 is typically removed prior to FT synthesis and also for the synthesis of oxygenates.

[0012] RWGS in the higher temperature range can be carried out using catalysts (e.g., Ni-based) in either SMR-type reactors (largely isothermal, externally heated) or autothermal reforming (ATR)-type reactors. Alternatively, the feed H2+CO2 can be preheated to a high enough temperature (e.g., above 800-900 °C) to feed into an adiabatic fixed-bed reactor, since the RWGS endotherm of the reaction is relatively low. Autothermal catalytic approaches with methanation co-reaction providing heat for the RWGS reaction are also known, but have the disadvantage of requiring separation of CH4 from the CO effluent.

[0013] Alternatively, the RWGS reaction can be carried out without a catalyst at higher temperatures (up to 1500° C.), but at such temperatures a refactored reactor is required (e.g., POX type).

[0014] Even at higher temperature ranges, the extent of conversion of CO2 to CO is somewhat limited, necessitating a large excess of hydrogen that must be separated and recycled downstream, and / or removal and recycling of the CO2.

[0015] Therefore, there remains a need to provide for the design and development of cost-effective RWGS reaction systems and their integration into specific plant designs and operations. Summary of the Invention

[0016] A method for increasing carbon monoxide (CO) production and recycling carbon dioxide during synthesis gas processing is provided, the method comprising the steps of passing a first synthesis gas stream comprising hydrogen, carbon monoxide, and carbon dioxide through a first separation zone, thereby separating the first synthesis gas stream into a second stream comprising hydrogen and carbon monoxide and a third stream comprising carbon dioxide; feeding the third stream to a carbon dioxide to carbon monoxide conversion unit to produce a fourth stream comprising carbon monoxide and a fifth stream comprising oxygen; mixing the second stream and the fourth stream to produce a synthesis gas product stream; and feeding the synthesis gas product stream to a product synthesis unit.

[0017] A method for increasing carbon monoxide (CO) production and recycling carbon dioxide during processing of synthesis gas, comprising the steps of passing a first synthesis gas stream, the first synthesis gas stream comprising hydrogen, carbon monoxide, and carbon dioxide, through a first separation zone, thereby separating the first synthesis gas stream into a second stream comprising hydrogen and carbon monoxide and a third stream comprising carbon dioxide; combining the third stream with a hydrogen stream to produce a fourth stream comprising carbon dioxide and hydrogen; and passing the fourth stream through a carbon dioxide to carbon monoxide conversion unit comprising a reverse water gas shift (RWGS) reactor. passing the fifth stream through a second separation zone to remove unreacted carbon dioxide and produce a CO2-depleted syngas stream, wherein the unreacted carbon dioxide is combined with the hydrogen stream and recycled back to the third stream for feeding to the RWGS reactor; combining H2 and CO from the second stream with H2 and CO from the CO2-depleted syngas stream to produce a syngas product stream; and feeding the syngas product stream to a product synthesis unit.

[0018] In one embodiment, a second separation zone is combined with the first separation zone, a fifth stream of the RWGS reactor product is recycled back to the first separation zone, and CO2 is recovered in-situ from the fifth and first streams, and a third stream comprising carbon dioxide from both streams is produced.

[0019] In another embodiment, the H2 and CO from the fifth stream are combined with the H2 and CO from the first stream in the first separation zone to produce a second stream comprising hydrogen and carbon monoxide and to produce a synthesis gas product stream, which is fed to a product synthesis unit.

[0020] In one embodiment, the method described herein further comprises mixing the synthesis gas product stream with additional hydrogen to adjust the stoichiometric requirements of the product synthesis unit.

[0021] In another embodiment, the product synthesis unit is a Fischer-Tropsch reactor.

[0022] In a further embodiment, the first and second separation zones include a CO2 selective solvent, a CO2 adsorption step, and a solvent regeneration step to produce the desired carbon dioxide stream.

[0023] In one embodiment, the CO2 selective solvent is methanol, ethanol, N-methyl-2-pyrrolidone (NMP), an amine, propylene carbonate, dimethyl ether of polyethylene glycol (DMPEG), methyl isopropyl ether of polyethylene glycol (MPEG), tributyl phosphate, or sulfolane.

[0024] In a complementary embodiment, all or a portion of the hydrogen stream is used as a stripping gas to extract CO2 from a CO2-selective solvent in a first separation zone containing hydrogen in a third stream containing carbon dioxide, reducing the amount of hydrogen to produce a fourth stream.

[0025] In one embodiment, all or a portion of the hydrogen stream is used as a stripping gas to extract CO2 from a CO2-selective solvent in a second separation zone, thereby producing an unreacted carbon dioxide RWGS stream and additional hydrogen.

[0026] In a further embodiment, the first and second separation zones comprise at least one membrane that is permeable to carbon dioxide and retains hydrogen and / or carbon monoxide.

[0027] In a further embodiment, the first and second separation zones comprise at least one PSA or VPSA system that removes carbon dioxide and carbon monoxide from the hydrogen to produce a hydrogen-rich stream and releases the carbon dioxide and carbon monoxide into a low pressure stream.

[0028] In one embodiment, the water-containing effluent is generated from a RWGS reactor.

[0029] In another embodiment, the effluent of the RWGS reactor is cooled to condense and separate the water produced by the RWGS reaction.

[0030] In one embodiment, the carbon dioxide to carbon monoxide conversion unit is either a CO2 electrolysis unit or a CO2 + H2O co-electrolysis unit.

[0031] In another embodiment, the RWGS reactor is a heated catalytic multi-tube reactor design, an autothermal catalytic reactor, a fixed bed adiabatic catalytic reactor, or a combination thereof.

[0032] In a further embodiment, the RWGS reactor comprises a nickel catalyst or an iron-based catalyst.

[0033] In one embodiment, the RWGS reactor is a high temperature autothermal POX type reactor that does not use a catalyst.

[0034] In a further embodiment, the first synthesis gas stream is produced from partial oxidation, gasification, and / or reforming of a carbonaceous feedstock.

[0035] In one embodiment, the carbonaceous material comprises plastics, metals, inorganic salts, organic compounds, industrial waste, recycling plant waste, automobile fluff, municipal solid waste, ICI waste, C&D waste, refuse derived fuels (RDF), solid recovered fuels, sewage sludge, used utility poles, railway sleepers, wood, tires, synthetic fibers, carpet, synthetic rubber, fossil fuel derived materials, expanded polystyrene, polyfilm flock, building wood materials, or any combination thereof.

[0036] In another embodiment, the source of hydrogen is derived from a renewable source and / or a source with low carbon intensity.

[0037] In further embodiments, the source of hydrogen is derived from renewable or low carbon intensity powered water electrolysis, biogas reforming, steam reforming, a low carbon intensity (CI) blue hydrogen source, or a low CI waste H2 source.

[0038] In one embodiment, the methods encompassed herein further include mixing the third stream with an external input of CO or a CO input obtained from another process effluent to increase the CO flow rate upstream of the CO2-to-CO conversion unit, thereby increasing the flow rate of CO in the synthesis gas product stream.

[0039] In one embodiment, the method encompassed herein further comprises mixing the third stream with a reformed low carbon intensity (CI) carbon-rich stream to increase the carbon content upstream of the CO2 to CO conversion unit, thereby increasing the flow rate of CO in the synthesis gas product stream.

[0040] In one embodiment, the carbon-rich stream is a waste gas or liquid from a product synthesis unit.

[0041] In another embodiment, the carbon-rich stream is a gas or liquid from an external source.

[0042] In one embodiment, the carbon-rich stream is reformed or partially oxidized at high temperature upstream of the RWGS unit to produce additional synthesis gas, and 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 requirements of the process.

[0043] In one embodiment, the carbon-rich stream is reformed at high temperature upstream of the RWGS unit.

[0044] In another embodiment, the carbon-rich stream is reformed above 900° C. upstream of the RWGS unit.

[0045] In another embodiment, the reforming step is carried out in a reforming unit.

[0046] In another embodiment, the reforming unit is an autothermal catalytic reactor, a high temperature autothermal POX type reactor, or a dry reforming reactor.

[0047] Also provided is a method for increasing carbon monoxide (CO) production and recycling carbon dioxide during syngas processing, comprising: gasifying a carbonaceous material in a fluidized bed to produce a classified raw syngas; reforming the classified raw syngas at a temperature above a mineral melting point to produce a reformed syngas comprising hydrogen, carbon monoxide, and carbon dioxide; passing the reformed syngas to a first separation zone, thereby separating the first syngas stream into a second stream comprising hydrogen and carbon monoxide and a third stream comprising carbon dioxide; and recycling the third stream comprising carbon dioxide to a fluidized bed gasifier, with or without steam and / or O2, to reduce the reformed syngas H2 / CO ratio and increase overall CO yield and production.

[0048] In one embodiment, the second stream comprising hydrogen and carbon monoxide further comprises residual carbon dioxide and is passed to a second separation zone, thereby separating the second synthesis gas into a fourth stream comprising hydrogen and carbon monoxide and a fifth stream comprising carbon dioxide, the fifth stream is combined with a hydrogen stream to produce a sixth stream comprising carbon dioxide and hydrogen, the sixth stream is fed to a carbon dioxide to carbon monoxide conversion unit consisting of a reverse water gas shift (RWGS) reactor to produce a seventh stream comprising carbon monoxide, hydrogen and unreacted carbon dioxide, the seventh stream is passed to a third separation zone to remove unreacted carbon dioxide and produce a CO2-depleted synthesis gas stream, which is combined with the hydrogen stream and recycled back to the fifth stream for feeding the RWGS reactor, the fourth stream is combined with the CO2-depleted synthesis gas stream to produce a synthesis gas product stream, and the synthesis gas product stream is fed to a product synthesis unit.

[0049] In one embodiment, the method described herein further comprises mixing the synthesis gas product stream with additional hydrogen to adjust the stoichiometric requirements of the product synthesis unit.

[0050] In another embodiment, the first, second, and third separation zones include a CO2-selective solvent, a CO2 adsorption step, and a solvent regeneration step to produce a desired carbon dioxide stream.

[0051] In a further embodiment, the first, second and / or third separation zones are combined into a single separation zone.

[0052] In one embodiment, the hydrogen stream is used as a stripping gas to extract CO2 from the CO2-selective solvent in the first separation zone, the second separation zone, and / or the third separation zone.

[0053] In a further embodiment, the first, second, and third separation zones comprise at least one membrane that is permeable to carbon dioxide and retains hydrogen and / or carbon monoxide.

[0054] In one embodiment, the first, second, and third separation zones comprise at least one PSA or VPSA system that removes carbon dioxide and carbon monoxide from the hydrogen to produce a hydrogen-rich stream and releases the carbon dioxide and carbon monoxide into a lower pressure stream.

[0055] In one embodiment, waste gases or liquids from the product synthesis unit are recycled to the gasification and / or reforming steps.

[0056] Reference is now made to the accompanying drawings, in which: [Brief description of the drawings]

[0057] [Figure 1] FIG. 1 shows a schematic diagram of a method for integrating a RWGS step according to one embodiment. [Diagram 2] FIG. 1 shows a schematic diagram of an alternative process including one single CO2 separation zone according to one embodiment. [Diagram 3] FIG. 1 shows a schematic diagram of an alternative method in which the captured CO2 and / or waste gas and / or waste liquid can be recycled in the gasification and reforming steps according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] It should be noted that throughout the accompanying drawings, like features are identified by like reference numbers.

[0059] According to the present disclosure, a method is provided for increasing carbon monoxide (CO) production and recycling carbon dioxide when processing synthesis gas using a carbon dioxide to carbon monoxide conversion unit.

[0060] By minimizing the amount of CO2 required to inert and pressurize the feedstock, isolating a CO2-rich stream, and converting it to CO to further synthesize FT products, a means is provided to optimize the amount of carbon recycle of waste materials. As encompassed herein, any hydrocarbon waste stream can be converted to additional synthesis gas, which further increases the amount of available CO, which further increases carbon recycle.

[0061] When an external source of green, renewable, or low carbon intensity hydrogen is available, the integration of a reverse water gas shift (RWGS) unit or an alternative CO2 to CO conversion unit to convert excess CO2 from the produced syngas into additional CO provides a method to maximize the yield of CO obtained from partial oxidation, gasification, and / or reforming of a carbonaceous feedstock.

[0062] Partial oxidation, gasification, and / or reforming of some carbonaceous solid, liquid, or gaseous feedstocks ultimately produces a crude syngas stream with a H2 / CO ratio of less than 2.0, as required according to stoichiometry for the production of methanol, other alcohols, and / or hydrocarbons (i.e., Fischer-Tropsch). The H2 / CO ratios produced from these processes are often less than 1.5, and often as low as 0.7 or less. In addition to H2 and CO, partial oxidation, gasification, and / or reforming processes always produce CO2, which is present in the crude syngas at various concentrations depending on the process efficiency and the feedstock heating value.

[0063] In coal or liquid fossil fuel gasification and / or reforming plants that produce a raw syngas with lower H2 / CO than required per the ratio derived from the stoichiometric reaction 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 to additional H2 to rebalance the overall plant H2 / CO ratio (according to reaction 5 above), or alternatively, in situ shift to additional H2, for example using an Fe-based Fischer-Tropsch in the desired project syngas synthesis reactor. Since the entire plant has excess CO2, a process unit is required for CO2 removal. Since these feedstocks also typically contain sulfur, and sulfur is converted to reduced sulfur species (H2S, COS, etc.) in the gasification and / or reforming units, such typical plants also include an acid gas removal (AGR) unit that removes both CO2 and sulfur reduced species. Reduced sulfur species are poisons to some syngas conversion catalysts and are also undesired in most final chemical and / or biofuel products.

[0064] In biomass-rich or waste gasification and / or reforming valorization plants, such an approach has the adverse effect of losing valuable biogenic carbon via carbon monoxide shift, which results in excess CO2 rather than a final biogenic product, which the plant must valorize as very low value commercial CO2 and / or safely release to the atmosphere after processing, increasing the greenhouse gas impact of the plant.

[0065] In such plants using bio-based carbonaceous feedstocks, it has been demonstrated that rather than shifting the excess CO to H, an external source of hydrogen can be introduced into the plant and combined with the plant-rich CO biosyngas to rebalance the overall plant H2 / CO ratio to that required for the stoichiometric reaction of the desired end products.

[0066] It is also known that some chemicals and biofuels can be produced not only from the reaction of H2 and CO, but also from H2 and CO2. One such product is methanol, but also Fischer-Tropsch using iron-based catalysts and ethanol using microbial biocatalysts. However, other types of synthetic catalysts, including Co-based Fischer-Tropsch catalysts as previously described, do not offer this capability. Similarly, in the chemical industry, acetic acid is produced from the carbonylation of methanol and CO, and cannot be produced directly from CO2.

[0067] Thus, for example and without limitation, Co-based catalyzed Fischer-Tropsch production from gasification and / or reforming of biomass, biomass-rich wastes and / or waste plastics is used to provide a means to maximize overall carbon feedstock conversion to final desired chemicals or fuels.

[0068] As seen in FIG. 1, a synthesis gas stream (1) is provided with a H2 / CO ratio of less than 2 and excess CO2 produced by most carbonaceous feedstock gasification and / or reforming processes.

[0069] An external input of hydrogen (4) is provided from an external source (i.e., not produced from the same synthesis gas production unit) in an amount and ratio sufficient to completely convert the desired amount of excess CO2 into additional CO (according to reaction 2).

[0070] The CO2-rich syngas (1) is sent to a first CO2 separation zone (2) to produce a CO2-depleted syngas (H2+CO rich) (9) and a rich CO2 stream (3). This rich CO2 stream (3) is then mixed with a portion or the entirety of an external hydrogen stream (H2 feed #1) (4) and then fed to a RWGS unit (5) to convert the CO2 to CO, thereby producing a new syngas stream (6). The RWGS reactor effluent is first cooled and condensed to separate the water produced by the RWGS reaction, and then fed to a second CO2 separation zone (7) to remove unconverted CO2 (13) and recycle it to the RWGS unit (5). Alternatively, a portion of the H2 feed (4' and / or 4'') can be fed to the first CO2 separation zone (2) and / or the second CO2 separation zone (7) for use as a stripping gas when using a solvent-based CO2 removal unit as described below. It is contemplated that CO2 input from external CO2 or another process effluent (14) can be mixed with the CO2-rich stream (3) upstream of the RWGS unit (5) to further increase the production of CO. The flow rate of the external source of hydrogen (4) must be increased accordingly.

[0071] As encompassed herein, the CO2 separation zone includes a solvent-based gas scrubbing system having a solvent selective for carbon dioxide absorption or a CO2-selective solvent, a CO2 absorption step, and a solvent regeneration step to generate the desired carbon dioxide stream. In one embodiment, the CO2-selective solvent is, for example, but not limited to, methanol, ethanol, N-methyl-2-pyrrolidone (NMP), amines, propylene carbonate, dimethyl ether of polyethylene glycol (DMPEG), methyl isopropyl ether of polyethylene glycol (MPEG), tributyl phosphate, or sulfolane. Instead of a solvent-based CO2 separation zone, the first and second separation zones described herein can also include a membrane unit that is permeable to carbon dioxide and retains hydrogen and / or carbon monoxide. Other alternative CO2 separation zones can include, but are not limited to, a solid sorbent system for selective adsorption of CO2 and / or CO using pressure or thermal swing technology.

[0072] The fresh CO2-depleted syngas stream or syngas product (8) from the RWGS and CO2 separation zone is then combined with the CO2-depleted syngas (9) described above and fed to a desired product synthesis unit (12), such as, but not limited to, a Fischer-Tropsch reactor. If necessary, the remainder of the external hydrogen feed (H2 feed #2) (10) is combined with the CO2-depleted syngas stream to rebalance the overall plant H2 / CO ratio to that required according to the ratio derived from the stoichiometric reaction of the desired end product, which is the Fischer-Tropsch product produced from reaction 4 as exemplified herein.

[0073] The product synthesis unit (12) converts the H2-conditioned CO2-depleted synthesis gas (11) to the final product (15). It is contemplated that waste gas and / or waste liquid (16) from the product synthesis unit can be recycled through a reforming unit, such as, but not limited to, an autothermal catalytic reactor (e.g., ATR) or a high-temperature autothermal POX type reactor (non-catalytic) (17), or a dry reforming reactor (see FIG. 2). A high-temperature (e.g., above 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, thereby reducing the energy requirements of the overall process. It is also contemplated that the waste gas and / or waste liquid can be recycled in the gasification and reforming step (19) (as shown in FIG. 3). This allows for the recycling of carbon from the waste stream (16), thereby increasing the production of CO and improving the overall efficiency. A portion of the waste stream (16′) can be purged to avoid the accumulation of inert gases. It is also contemplated that the waste stream (16) may be used as fuel (16'') in the RWGS unit (5), such as a RWGS reactor feed preheater (combustion type). Alternatively, energy sources with low carbon intensity (i.e., GHG emissions), such as renewable fuels and / or renewable electricity, may be used to provide heat in the RWGS unit.

[0074] In one embodiment, the RWGS reactor encompassed herein is an externally heated catalytic multi-tube reactor design, an autothermal catalytic reactor (ATR type with oxygen injection to further increase the feed temperature before the adiabatic RWGS reactor catalyst bed) or a fixed bed adiabatic catalytic reactor, or any combination thereof. The catalyst in the RWGS reactor may be, but is not limited to, a nickel or iron based catalyst. It is also encompassed that the RWGS reactor described herein may be a high temperature autothermal POX type reactor with oxygen injection similar to the ATR type but without a catalyst.

[0075] It is also contemplated that the external source of hydrogen may be generated from renewable sources and / or low carbon intensity (i.e., GHG emissions), including, but not limited to, water electrolysis with renewable electricity, biogas reforming or steam reforming, or low carbon intensity (CI) blue hydrogen (fossil fuel methane reforming with CO2 capture), low CI waste H2, etc.

[0076] As encompassed herein, the synthesis gas stream results from the gasification of carbonaceous materials. The carbonaceous materials encompassed herein may be biomass-rich materials that can be gasified as described in International Application No. PCT / CA2020 / 050464 (the contents of which are incorporated by reference in their entirety), including, but not limited to, homogeneous biomass-rich materials, heterogeneous biomass-rich materials, non-homogeneous biomass-rich materials, and urban biomass. The carbonaceous material may also be plastic-rich residues, or any waste / product / gas / liquid / solid that contains carbon. It may also be any type of coal and derivatives, such as petroleum coke, petroleum products and by-products, waste oil, oil-based fuels, hydrocarbons, and tars.

[0077] Homogeneous biomass-rich materials are biomass-rich materials derived from a single source. Such materials include, but are not limited to, materials from a single species of coniferous or deciduous tree, agricultural materials from a single species of plant, such as hay, corn, or wheat, or primary sludge from wood pulp, and wood chips, for example. It may also be refined, single-source materials, such as waste cooking oil, lychee fruit bark, etc.

[0078] Heterogeneous biomass-rich materials are generally materials obtained from two or more species of plants, including, but not limited to, forest residues from mixed species and wood residues from mixed species obtained from debarking or sawmilling operations.

[0079] Heterogeneous biomass-rich materials are generally materials that contain 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 waste, recycling plant waste, automobile fluff and waste, urban biomass such as municipal solid waste, waste-derived fuels (RDF), solid recovered fuels, sewage sludge, tires, synthetic fibers, carpets, synthetic rubber, expanded polystyrene, polymeric film flock, used wooden utility poles and wooden sleepers that may have been treated with creosote oil, pentachlorophenol, or copper chromium arsenate, and wood from construction and demolition operations that may contain paints and resins in addition to one of the above chemicals.

[0080] As encompassed herein, the synthesis gas stream resulting from the gasification of carbonaceous materials also requires additional conditioning and processing to make it suitable for the product synthesis unit.

[0081] As mentioned above, an AGR unit and guard bed filter are utilized upstream of the product synthesis unit to achieve very low contaminant levels in the syngas. The AGR unit also has the ability to remove a portion of the CO2 from the acid syngas, producing a non-flammable CO2 stream suitable for pressurization and inerting of carbonaceous feedstocks in the gasification step, as well as other purges requiring inert gas.

[0082] Upstream of the AGR, as also described in International Application No. PCT / CA2020 / 050464, the gasification plant may also include a feed system for feeding the carbonaceous material to a fluidized bed gasifier to produce a raw synthesis gas, which is then thermally reformed at a temperature above the melting point of the carbonaceous material ash (minerals) to produce a reformed synthesis gas (syngas). In one embodiment, the fluidizing agent is air, oxygen, carbon dioxide, nitrogen, steam, or any combination thereof in any proportion. The gasification plant may also include a high temperature reformer syngas quench and heat recovery, and may include additional cleaning stages including particulate removal, ammonia removal, chlorine removal, and other catalyst poison removal, for example by wet water gas scrubbers.

[0083] In one embodiment, the carbonaceous material can be fed as low density fluff RDF by the feeding system, lowering the cost of feedstock pretreatment by only partially pretreating the RDF fluff. In another embodiment, the carbonaceous material can be a mixture of low density fluff with particle sizes ranging from a few millimeters to a few centimeters. In a non-limiting embodiment, the carbonaceous material can be in a high density pelletized form with or without low density fluff. In another non-limiting embodiment, the carbonaceous material can be a solid, liquid, gas, or any composition in any proportion thereof that contains carbon atoms. In all cases, the non-combustible CO2 stream extracted from the AGR can be used as a low cost inert gas for pressurization and inerting of the carbonaceous feedstock in the gasification step. The use of CO2 as an inert gas not only removes O2 trapped in the bulk carbonaceous material feedstock making it safe for injection into the gasifier, but also removes trapped N2, which reduces the downstream syngas partial pressure in the product synthesis unit, thereby increasing the inert and non-condensable gas purge rate and the loss of valuable syngas, reducing the desired product yield.

[0084] In one embodiment, as seen in FIG. 3, additional AGR extracted CO2 (3) can be recycled to the fluidized bed gasifier (19) to be used as a fluidizing agent and / or in combination with steam (20) and / or oxygen (21) to adjust and optimize the reformed syngas H2 / CO ratio. In another non-limiting embodiment, such a CO2 fluidizing agent may be another source of CO2 extracted from the plant and / or an external CO2 source (14). A higher CO2 to steam ratio in the gasifier fluidized bed allows for maximizing the CO yield and thus the FT product yield. It is contemplated that these steps may be used with and without the current RWGS integration combinations described herein.

[0085] The ratio or flow rate of H2 feed #1 (4) depends on the amount of excess CO2 that is converted to CO and achieves high efficiency in the RWGS unit. A distinctive feature of the process provided herein is that it utilizes the total additional H2 feed required in the plant, including the H2 required to convert the CO load from the original syngas stream (1). Thus, this new integrated process utilizes this additional feed of H2 and uses it at least partially within the RWGS unit to optimize the CO2 single pass conversion, reducing the size, CAPEX, and energy consumption associated with the CO2 removal and recycle steps, and eliminating the need for a H2 separation step, further reducing CAPEX and energy consumption.

[0086] Table 1 below shows examples of splits between syngas streams H2 feed #1 (4) and H2 feed #2 (10) at different CO2 levels. For simplicity, the H2 / CO ratio of 1 is fixed for all cases based on 100 kmol / h syngas and assumes 100% CO2 removal and recycle (although in practice a maximum of about 95% applies). [Table 1] a Total H2 based on a desired H2 / CO ratio of 2.0 is fed into the final syngas stream that is fed to downstream syngas conversion units to the desired end products. The split between H2 feed #1 and H2 feed #2 depends on the extent of single pass CO2 conversion to CO in the RWGS, which depends on the H2 / CO2 ratio feed to the RWGS unit and the reactor operating temperature. For the purposes of demonstrating the present invention, a high temperature RWGS was used. b % CO production increase is "Total CO plant production (kmol / h)" divided by CO in baseline feed syngas (kmol / h). The increase in FT product yield is proportional to the increase in CO production.

[0087] Alternatively, the first and second CO2 separation zones can be combined into one single CO2 separation zone (Figure 2), which further reduces the CAPEX of this novel design. Another alternative could be the combination of the first and / or second CO2 separation zones with AGR, followed by guard bed filters on the CO2 stream (3) and the CO2-depleted syngas stream (9) to remove trace contaminants in both streams.

[0088] In further embodiments, other CO2 to CO conversion techniques can be integrated, such as electrolysis of CO2 to CO and O2, or co-electrolysis of CO2+H2O to H2+CO and O2, as presented above (Equations 6 and 7). In the case of CO2 electrolysis, H2 feed #1 (4) is zero and the total H2 feed is entirely provided via H2 feed #2 (10). In the case of CO2+H2O co-electrolysis, H2 feed #1 (4) is also zero and the total H2 feed is provided via H2 feed #2 (10) is reduced by the amount of H2 produced by the co-electrolysis step.

[0089] Several different methods can be used for the CO2 separation step. It can be a CO2 selective membrane separation technology, e.g., Polaris from MTR or PIX from Air Liquid. It can be an amine CO2 solvent method with a CO2 adsorption step and a CO2 recovery step from solvent regeneration. In a preferred alternative, chilled methanol is used as the solvent. In a further preferred alternative, a simple chilled methanol pressure swing CO2 absorption / desorption can be performed, using inlet #1 hydrogen (streams 4' and / or 4'') as the CO2 stripping gas to further reduce the energy consumption requirements of the CO2 removal step.

[0090] While the disclosure has been described in relation to particular embodiments thereof, it is to be understood that it is capable of further modifications, and this application is intended to cover any variations, uses, or adaptations thereof, including departures from the disclosure to the essential features described hereinabove which are known or customarily made in the art, and which fall within the scope of the appended claims.

Claims

1. 1. A method for increasing carbon monoxide (CO) production and recycling carbon dioxide during synthesis gas processing, 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 the third stream to a carbon dioxide to carbon monoxide conversion unit to produce a fourth stream comprising carbon monoxide and a fifth stream comprising oxygen; mixing the second stream with the fourth stream to produce a synthesis gas product stream; and supplying said synthesis gas product stream to a product synthesis unit.

2. 1. A method for increasing carbon monoxide (CO) production and recycling carbon dioxide during synthesis gas processing, comprising the steps of: passing a first synthesis gas stream, said 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; combining the third stream with a hydrogen stream to produce a fourth stream comprising carbon dioxide and hydrogen; feeding the fourth stream to a carbon dioxide to carbon monoxide conversion unit comprising a reverse water gas shift (RWGS) reactor to produce a fifth stream comprising carbon monoxide, hydrogen, and unreacted carbon dioxide; The fifth stream is passed to a second separation zone to remove the unreacted carbon dioxide and to produce a CO ２ producing a depleted synthesis gas stream, wherein the unreacted carbon dioxide is recycled back to the third stream for combination with the hydrogen stream to feed the RWGS reactor; The H from the second stream ２ and CO, ２ H from the depleted syngas stream ２ and CO to produce a synthesis gas product stream; and supplying said synthesis gas product stream to a product synthesis unit.

3. The second separation zone is combined with the first separation zone, the fifth stream of RWGS reactor product is recycled back to the first separation zone, and the fifth and first streams are separated into the first separation zone and the second separation zone and the third separation zone are separated into the first separation zone and the fourth separation zone. ２ and generating said third stream comprising carbon dioxide from both streams.

4. The H from the fifth stream ２ and CO are separated from the H from the first stream in the first separation zone. ２ and CO to produce the second stream comprising hydrogen and carbon monoxide to produce the synthesis gas product stream, and the synthesis gas product stream is fed to the product synthesis unit.

5. 5. The method of any one of claims 2 to 4, further comprising mixing the synthesis gas product stream with additional hydrogen to adjust the stoichiometric requirements of the product synthesis unit.

6. The process of any one of claims 1 to 4, wherein the product synthesis unit is a Fischer-Tropsch reactor.

7. The first and second separation zones are configured to separate a CO ２ Selective Solvent, CO ２ The method according to any one of claims 2 to 4, comprising an adsorption step and a solvent regeneration step.

8. The CO ２ 7. The method of claim 6, wherein the selective solvent is methanol, ethanol, N-methyl-2-pyrrolidone (NMP), an amine, propylene carbonate, dimethyl ethers of polyethylene glycol (DMPEG), methyl isopropyl ethers of polyethylene glycol (MPEG), tributyl phosphate, or sulfolane.

9. In the first separation zone, all or a portion of the hydrogen stream is used as a stripping gas, and the CO ２ Selective solvent to CO ２ and reducing the amount of said hydrogen to produce said fourth stream.

10. All or a portion of the hydrogen stream is used as a stripping gas, and in the second separation zone, the CO ２ Selective solvent to CO ２ and extracting said unreacted carbon dioxide RWGS stream and additional hydrogen, thereby producing an unreacted carbon dioxide RWGS stream and additional hydrogen.

11. 9. The method of claim 8, wherein the first and second separation zones comprise at least one membrane that is permeable to carbon dioxide and retains hydrogen and / or carbon monoxide.

12. The method of any one of claims 2 to 4, wherein an effluent comprising water is produced from the RWGS reactor.

13. 13. The method of claim 12, wherein the RWGS reactor effluent is cooled to condense and separate the water produced by the RWGS reaction.

14. The carbon dioxide to carbon monoxide conversion unit ２ Electrolysis unit or CO ２ +H ２ 2. The method of claim 1 , wherein the O co-electrolysis unit is a

15. 15. The method of any one of claims 2 to 4 and 14, wherein the RWGS reactor is a heated catalytic multi-tubular reactor design, an autothermal catalytic reactor, a fixed bed adiabatic catalytic reactor, or a combination thereof.

16. The method of claim 15 , wherein the RWGS reactor comprises a nickel catalyst or an iron-based catalyst.

17. The method according to any one of claims 2 to 4 and 14, wherein the RWGS reactor is a high temperature autothermal POX type reactor without a catalyst.

18. The method of any one of claims 1 to 4 and 14, wherein the first synthesis gas stream is produced from partial oxidation, gasification, and / or reforming of a carbonaceous feedstock.

19. 20. The method of claim 18, wherein the carbonaceous material comprises plastics, metals, inorganic salts, organic compounds, industrial waste, recycling plant waste, automobile fluff, municipal solid waste, ICI waste, C&D waste, refuse derived fuels (RDF), solid recovered fuels, sewage sludge, used utility poles, railroad ties, wood, tires, synthetic fibers, carpet, synthetic rubber, fossil fuel derived materials, expanded polystyrene, polyfilm flock, building wood materials, or any combination thereof.

20. The method of any one of claims 2 to 4 and 14, wherein the source of hydrogen is derived from a renewable source and / or a source with low carbon intensity.

21. The source of hydrogen is water electrolysis using renewable or low carbon intensity electricity, biogas reforming, steam reforming, low carbon intensity (CI) hydrogen sources, or low carbon intensity waste H ２ 21. The method of claim 20, wherein the source is

22. The third stream is ２ of CO obtained from external inputs or process effluents ２ Mixing the inputs and ２ CO upstream of the CO to CO conversion unit ２ 15. The method of any one of claims 1 to 4 and 14, further comprising increasing the flow rate, thereby increasing the flow rate of CO in the synthesis gas product stream.

23. mixing said third stream with a reformed low carbon intensity (CI) carbon-rich stream; ２ 15. The method of any one of claims 1 to 4 and 14, further comprising increasing the carbon content upstream of a CO to CO conversion unit, thereby increasing the flow rate of CO in the synthesis gas product stream.

24. 24. The method of claim 23, wherein the carbon-rich stream is a waste gas or liquid from the product synthesis unit.

25. 25. The method of claim 24, wherein the carbon-rich stream is a gas or liquid from an external source.

26. 24. The method of claim 23, wherein the carbon-rich stream is reformed or partially oxidized at high temperature upstream of the RWGS unit to produce additional synthesis gas, and the hot reformed waste stream is mixed at the inlet of the RWGS unit to provide all or a portion of the heat required for the endothermic RWGS reactor and reduce the energy requirements of the method.

27. 27. The method of claim 26, wherein the carbon-rich stream is reformed above 900°C upstream of the RWGS unit.

28. 27. The method of claim 26, wherein the reforming step is carried out in a reforming unit.

29. 29. The method of claim 28, wherein the reforming unit is an autothermal catalytic reactor, a high temperature autothermal POX type reactor, or a dry reforming reactor.

30. 1. A method for increasing carbon monoxide (CO) production and recycling carbon dioxide during synthesis gas processing, comprising the steps of: a. gasifying a carbonaceous material in a fluidized bed to produce a classified raw syngas; b. reforming the classified raw syngas at a temperature above a mineral melting point to produce a reformed syngas comprising hydrogen, carbon monoxide, and carbon dioxide; c. passing the reformed syngas through a first separation zone, thereby separating the first syngas stream into a second stream comprising hydrogen and carbon monoxide and a third stream comprising carbon dioxide; d. Water vapor and / or O ２ and recycling the third stream containing carbon dioxide to the fluidized bed gasifier to produce the reformed synthesis gas H. ２ and decreasing the CO / CO ratio and increasing the overall CO yield and production.

31. 31. The method of claim 30, wherein the carbonaceous material comprises plastics, metals, inorganic salts, organic compounds, industrial waste, recycling plant waste, automobile fluff, municipal solid waste, ICI waste, C&D waste, refuse derived fuels (RDF), solid recovered fuels, sewage sludge, used utility poles, railroad ties, wood, tires, synthetic fibers, carpet, synthetic rubber, fossil fuel derived materials, expanded polystyrene, polyfilm flock, building wood materials, or any combination thereof.

32. the second stream comprising hydrogen and carbon monoxide further comprising residual carbon dioxide is passed to a second separation zone, thereby separating the second synthesis gas into a fourth stream comprising hydrogen and carbon monoxide and a fifth stream comprising carbon dioxide; combining the fifth stream with a hydrogen stream to produce a sixth stream comprising carbon dioxide and hydrogen; feeding the sixth stream to a carbon dioxide to carbon monoxide conversion unit comprising a reverse water gas shift (RWGS) reactor to produce a seventh stream comprising carbon monoxide, hydrogen, and unreacted carbon dioxide; The seventh stream is passed to a third separation zone to remove the unreacted carbon dioxide and to produce a CO ２ producing a depleted synthesis gas stream, said unreacted carbon dioxide being recycled back to said fifth stream for combination with said hydrogen stream to feed said RWGS reactor; The fourth stream and the CO ２ and combining the depleted syngas stream to produce a syngas product stream; 32. The method of claim 30 or 31, wherein the synthesis gas product stream is fed to a product synthesis unit.

33. 33. The method of claim 32, further comprising mixing the synthesis gas product stream with additional hydrogen to adjust the stoichiometric requirements of the product synthesis unit.

34. 33. The method of claim 32, wherein the product synthesis unit is a Fischer-Tropsch reactor.

35. The first, second, and third separation zones are configured to separate CO 2 from the first, second, and third separation zones to produce a desired carbon dioxide stream. ２ Selective Solvent, CO ２ 32. The method of claim 30 or 31, comprising an adsorption step and a solvent regeneration step.

36. 31. The method of claim 30, wherein the first, second and / or third separation zones are combined into a single separation zone.

37. The CO ２ 36. The method of claim 35, wherein the selective solvent is methanol, ethanol, N-methyl-2-pyrrolidone (NMP), an amine, propylene carbonate, dimethyl ethers of polyethylene glycol (DMPEG), methyl isopropyl ethers of polyethylene glycol (MPEG), tributyl phosphate, or sulfolane.

38. The hydrogen stream is used as a stripping gas to remove the CO ２ Selective solvent to CO ２ The method of claim 32, further comprising extracting:

39. 33. The method of claim 32, wherein the first, second, and third separation zones comprise at least one membrane that is permeable to carbon dioxide and retains hydrogen and / or carbon monoxide.

40. 33. The method of claim 32, wherein the first, second, and third separation zones comprise at least one PSA or VPSA system that removes carbon dioxide and carbon monoxide from hydrogen to produce a hydrogen-rich stream and releases the carbon dioxide and carbon monoxide into a lower pressure stream.

41. 33. The method of claim 32, wherein an effluent comprising water is produced from the RWGS reactor.

42. 42. The method of claim 41, wherein the RWGS reactor effluent is cooled to condense and separate the water produced by the RWGS reaction.

43. 33. The method of claim 32, wherein the RWGS reactor is a heated catalytic multi-tubular reactor design, an autothermal catalytic reactor, a fixed bed adiabatic catalytic reactor, or a combination thereof.

44. 44. The method of claim 43, wherein the RWGS reactor comprises a nickel catalyst or an iron-based catalyst.

45. 33. The method of claim 32, wherein the RWGS reactor is a high temperature autothermal POX type reactor without a catalyst.

46. 33. The method of claim 32, wherein the source of hydrogen is derived from a renewable source and / or a source with low carbon intensity.

47. The source of hydrogen is water electrolysis using renewable or low carbon intensity electricity, biogas reforming, steam reforming, low carbon intensity (CI) blue hydrogen sources, or low CI waste hydrogen sources. ２ 47. The method of claim 46, derived from a source.

48. 32. The method according to claim 30 or 31, wherein waste gas or liquid from the product synthesis unit is recycled to the gasification and / or reforming step.

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