A flexible fermentation platform for improved carbon dioxide conversion to products

Abstract

Integrated processes and systems for producing at least one gaseous fermentation product from a gas stream have been developed. The disclosure includes a variety of different flow schemes, including bioreactor tail gas recycle and CO2 extraction, such as a reverse water gas shift unit. 2 Improved carbon utilization through both bioreactor tail gas recycle and the use of a CO2 to CO2 conversion system. 2 The use of the CO conversion process is a preferred H2 feed to gas fermentation bioreactors for enhanced production of fermentation products. 2 :CO molar ratio. The bypass embodiment provides optimal sizing of the reverse water gas shift unit to minimize costs.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application Nos. 63 / 173,243, filed April 9, 2021, 63 / 173,247, filed April 9, 2021, 63 / 173,255, filed April 9, 2021, 63 / 173,262, filed April 9, 2021, and 63 / 282,546, filed November 23, 2021, which are incorporated herein by reference in their entireties.

[0002] The present disclosure relates to processes and systems that provide a flexible fermentation platform for improving the conversion of CO to products. In particular, the present disclosure relates to integrated processes and systems that benefit from improved product selectivity for gas fermentation platforms. [Background technology]

[0003] Carbon dioxide (CO2) accounts for approximately 76% of global greenhouse gas emissions from human activities, with methane (16%), nitrous oxide (6%), and fluorinated gases (2%) making up the remainder (United States Environmental Protection Agency). While industrial and forestry operations also release CO2 into the atmosphere, the majority of CO2 comes from burning fossil fuels to generate energy. Reducing greenhouse gas emissions, especially CO2, is critical to halting the progression of global warming and the associated changes in climate and weather.

[0004] It has long been recognized that gases containing carbon dioxide (CO), carbon monoxide (CO), and / or hydrogen (H) can be converted into various fuels and chemicals using catalytic processes such as the Fischer-Tropsch process. However, gas fermentation has recently emerged as an alternative platform for the biological fixation of such gases. Specifically, C1-fixing microorganisms have been demonstrated to convert gases containing CO2, CO, and / or H2, such as industrial waste gases or syngas or mixtures thereof, into products such as ethanol and 2,3-butanediol. Efficient production of such products can be limited, for example, by slow microbial growth, limited gas uptake, sensitivity to toxins, or diversion of carbon substrates to undesirable by-products.

[0005] Generally, the substrate and / or C1 carbon source serves as a partial or sole source of carbon, which can be derived from waste gases obtained as a by-product of an industrial process or from another source, such as combustion engine exhaust, CO2 by-product gas from industrial processes (e.g., cement production), ammonia production, by-product gas from syngas cleaning, ethylene production, ethylene oxide production, methanol synthesis), off-gas from fermentation processes (e.g., sugar to ethanol conversion), biogas, landfill gas, direct air capture, mined CO2 (fossil CO2), or electrolysis. The substrate and / or C1 carbon source can also be syngas produced by pyrolysis, torrefaction, reforming, or gasification. In other words, carbon in waste materials can be recycled by pyrolysis, torrefaction, reforming, or gasification to produce syngas for use as the substrate and / or C1 carbon source. The substrate and / or C1 carbon source can be a gas containing methane, and in certain embodiments, the substrate and / or C1 carbon source can be a non-waste gas.

[0006] Waste gases obtained from industrial processes or synthesis gases produced from synthesis gas sources may require treatment or degradation to make them suitable for use in gas fermentation systems. High CO2 content in industrial gases and / or synthesis gases has been shown to adversely affect the ethanol selectivity benefits of fermentation, resulting in higher production of undesirable co-products such as acetate and 2,3-butanediol.

[0007] Thus, there remains a need for a flexible fermentation platform that can accommodate reducing the CO content of industrial gases, syngas, or mixtures thereof before introduction into a bioreactor. Additionally, in some embodiments, there is a need to convert some of the CO present in syngas or industrial gases to CO before introduction into a bioreactor in order to vary and control the H:CO ratio. For example, lowering the H:CO ratio may improve microbial growth and increase the rate of growth, and may provide greater selectivity for fermentation products such as ethanol. Summary of the Invention

[0008] The disclosure involves an integrated process for the production of at least one fermentation product from a gas stream, the process comprising: a) obtaining a first gas stream comprising hydrogen and a second gas stream comprising CO; b) passing at least a portion of the first gas stream and at least a portion of the second gas stream through a CO to CO conversion system operating under conditions to produce a CO2-enriched outlet stream; c) passing the CO2-enriched outlet stream through a bioreactor having a culture of one or more C1-fixing bacteria and fermenting to produce at least one fermentation product stream and a bioreactor tail gas stream; d) compressing the bioreactor tail gas stream to produce a compressed bioreactor tail gas stream; and e) converting at least a portion of the compressed bioreactor tail gas stream into a CO2-enriched outlet stream. The method includes: passing at least a first portion of the compressed bioreactor tail gas stream, in any order, to a gas desulfurization and / or acid gas removal unit, or to a gas component removal unit, or to both the gas desulfurization and / or acid gas removal unit and the gas component removal unit, to produce a compressed treated bioreactor tail gas stream; f) recycling the compressed treated bioreactor tail gas stream and combining it with the first gas stream, the second gas stream, or a combination thereof, or passing it through a CO2-to-CO2 conversion system, or combining it with a CO2-enriched outlet stream, or any combination thereof; and g) optionally recycling a second portion of the compressed bioreactor tail gas stream and combining it with the CO2-enriched outlet stream or passing it through a bioreactor. The process may further include combining at least a second portion of the first gas stream, at least a second portion of the second gas stream, or a combination thereof with the CO2-enriched outlet stream. The process may further include passing at least a second portion of the first gas stream, at least a second portion of the second gas stream, or a combination thereof through a bioreactor. The process may further include compressing any portion of the first gas stream, the second gas stream, or a combination thereof. The process may further include controlling the relative amounts of the first portion of the compressed tail gas stream and the second portion of the compressed tail gas stream using a control valve.The process may further include passing at least a portion of the tail gas stream through a tail gas CO-to-CO conversion system selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit to produce a CO2-enriched eluate stream and recycling the second CO2-enriched eluate stream to the bioreactor. The CO2-enriched outlet stream may comprise an H2:CO:CO2 molar ratio of about 5:1:1, about 4.5:1:1, about 4.33:1:1, about 3:1:1, about 2:1:1, about 1:1:1, or about 1:3:1. The CO2-to-CO conversion system may include at least one of a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit. The at least one fermentation product may be selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol. The first gas stream comprising hydrogen may be produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof.The second gas stream containing CO may be produced by a gas source including at least one of a sugar-based ethanol source, a first-generation corn ethanol source, a second-generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugarbeet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefins source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO source, a natural gas processing source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof. The at least one C1-fixing bacterium may be selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei.

[0009] The present disclosure further includes an integrated process for the production of at least one fermentation product from a gas stream, the process comprising: a) obtaining a first gas stream comprising hydrogen and a second gas stream comprising CO; b) optionally compressing at least a portion of the first gas stream, at least a portion of the second gas stream, or any combination thereof in a first compressor to produce a compressed first gas stream, a compressed second gas stream, and / or a combination of the compressed first and second gas streams; and c) compressing at least a portion of the first gas stream, or the compressed first gas stream, or both, at least a portion of the second gas stream, or the compressed second gas stream, or both, or a combination of the compressed first and second gas streams. , a gas component removal unit, a gas desulfurization / acid gas removal unit, or both, to produce a treated stream; d) converting CO in at least a first portion of the treated stream to form CO in a CO to CO conversion system operating under conditions to produce a CO enriched outlet stream; e) passing the CO enriched outlet stream through a bioreactor having a culture of one or more C1 fixing bacteria and fermenting to produce at least one fermentation product stream and a bioreactor tail gas stream; and f) recycling the tail gas stream to the first compressor, gas processing zone, and CO to CO conversion system, the first gas stream, the second gas stream, or a combination of the first and second gas streams. The process may further include combining the CO2-enriched outlet stream with at least a portion of the treated stream, or the first gas stream, or the second gas stream, or a combination of the first and second gas streams, or the compressed first gas stream, or the compressed second gas stream, or a combination of the compressed first and second gas streams, or any combination thereof. The process may further include passing at least a portion of the tail gas stream through a tail gas CO2-to-CO2 conversion system selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit to produce a CO2-enriched eluate stream, and recycling the second CO2-enriched eluate stream to the bioreactor.The CO2-enriched outlet stream may further comprise hydrogen and CO2 and may comprise an H2:CO:CO2 molar ratio of about 5:1:1, about 4.5:1:1, about 4.33:1:1, or about 3:1:1, about 2:1:1, about 1:1:1, or about 1:3:1. The CO2-to-CO conversion system may include at least one of a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit. The gas processing zone may further include a deoxygenation unit, a catalytic hydrogenation unit, an adsorption unit, a thermal oxidizer, or any combination thereof. The at least one fermentation product can be selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol. The first gas stream comprising hydrogen can be produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof. The second gas stream comprising CO may be produced by a gas source including at least one of a sugar-based ethanol source, a first generation corn ethanol source, a second generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugar beet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefins source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO source, a natural gas processing source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof.At least one of the C1-fixing bacteria may be selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei. The CO2-enriched outlet stream may include hydrogen, and the process may further include separating the hydrogen from the CO2-enriched outlet stream and recycling the separated hydrogen to combine with the tail gas stream or the compressor. The process may further include compressing a remaining portion of the CO2-enriched outlet stream after separation of the hydrogen. The tail gas stream may include methane, and the process may further include passing a portion of the tail gas stream through a methane conversion unit to produce a methane conversion unit effluent and combining the methane conversion unit effluent with the tail gas stream. The process may further include producing an oxygen-containing stream from an oxygen source and passing the oxygen-containing stream through the methane conversion unit. The process may further include passing a second gas stream containing hydrogen from a hydrogen source through the bioreactor or combining it with a CO2-enriched outlet stream, passing a second gas stream containing CO2 from a CO2 source through the bioreactor or combining it with a CO2-enriched outlet stream, or any combination thereof. Combining a second gas stream that may contain hydrogen from a hydrogen source with a CO2-enriched outlet stream, or combining a second gas stream containing CO2 from a CO2 source with a CO2-enriched outlet stream, or both, may utilize mixing in a mixer. The ratio of the second gas stream may comprise hydrogen from the hydrogen source to the CO2-enriched outlet stream entering the bioreactor, and may be from about 0:1 to about 4:1. The CO2-to-CO2 conversion system may include a fired heater having a burner, and the tail gas stream is recycled to at least the burner of the fired heater. The CO2-to-CO2 conversion system may include a steam generator that generates steam, or a water knockout unit that generates a water stream, or both. The process may further include passing a portion of the CO2-enriched outlet stream through an inoculator reactor, a buffer tank, or both.

[0010] The present disclosure is directed to an integrated process for the production of at least one fermentation product from a gas stream, the process comprising: a) obtaining a first gas stream comprising hydrogen and a second gas stream comprising CO; b) passing at least a portion of the second gas stream and optionally at least a portion of the first gas stream through a CO to CO conversion system operating under conditions to produce a CO2-enriched outlet stream; c) passing at least a portion of the first gas stream comprising hydrogen and a CO2-enriched outlet stream through a bioreactor having a culture of one or more C1-fixing bacteria and fermenting to produce at least one fermentation product stream and a bioreactor tail gas stream; d) compressing the bioreactor tail gas stream to produce a compressed bioreactor tail gas stream; and e) converting the compressed bioreactor tail gas stream into a CO2-to-CO2 conversion system. The process includes passing at least a first portion of the bioreactor tail gas stream through a gas desulfurization and / or acid gas removal unit, or through a gas component removal unit, or both a gas desulfurization and / or acid gas removal unit and a gas component removal unit, in any order, to produce a compressed treated bioreactor tail gas stream; f) recycling the compressed treated bioreactor tail gas stream to combine with the first gas stream, the second gas stream, or a combination thereof, or through a CO2-to-CO2 conversion system, or combined with a CO2-enriched outlet stream, or any combination thereof; and g) optionally recycling a second portion of the compressed bioreactor tail gas stream to combine with the CO2-enriched outlet stream or pass to a bioreactor. The process may further include passing at least another portion of the first gas stream comprising hydrogen through a CO2-to-CO2 conversion system. The process may further include compressing any portion of the first gas stream, the second gas stream, or a combination thereof. The process may further include controlling the relative amounts of the first portion of the compressed tail gas stream and the second portion of the compressed tail gas stream using a control valve.The process may further include passing at least a portion of the tail gas stream through a tail gas CO-to-CO conversion system selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit to produce a CO2-enriched eluate stream and recycling the second CO2-enriched eluate stream to the bioreactor. The CO2-enriched outlet stream may comprise an H2:CO:CO2 molar ratio of about 5:1:1, about 4.5:1:1, about 4.33:1:1, about 3:1:1, about 2:1:1, about 1:1:1, or about 1:3:1. The CO2-to-CO conversion system may include at least one of a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit. The at least one fermentation product may be selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol. The first gas stream comprising hydrogen is produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof.The second gas stream, which may contain CO2, may be produced by a gas source including at least one of a sugar-based ethanol source, a first-generation corn ethanol source, a second-generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugarbeet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefins source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO2 source, a natural gas processing source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof. At least one of the C1-fixing bacteria may be selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei.

[0011] The disclosure involves an integrated process for the production of at least one fermentation product from a gas stream, the process comprising: obtaining a first gas stream comprising hydrogen and a second gas stream comprising CO; passing at least a portion of the first gas stream and at least a portion of the second gas stream through a CO-to-CO conversion system operating under conditions to produce a CO2-enriched outlet stream; fermenting the CO2-enriched outlet stream in a bioreactor having a culture of one or more C1-fixing bacteria to produce at least one fermentation product stream and a bioreactor tail gas stream; compressing the bioreactor tail gas stream to produce a compressed bioreactor tail gas stream; and converting at least a portion of the compressed bioreactor tail gas stream into a fermentation product stream. and passing at least a first portion of the compressed bioreactor tail gas stream, in any order, to a gas desulfurization and / or acid gas removal unit, or to a gas component removal unit, or to both the gas desulfurization and / or acid gas removal unit and the gas component removal unit, to produce a compressed treated bioreactor tail gas stream; and recycling the compressed treated bioreactor tail gas stream to combine with the first gas stream, the second gas stream, or a combination thereof, or to a CO2-to-CO2 conversion system, or to combine with a CO2-enriched outlet stream, or any combination thereof, and optionally recycling a second portion of the compressed bioreactor tail gas stream to combine with the CO2-enriched outlet stream or the bioreactor. At least a second portion of the first gas stream, at least a second portion of the second gas stream, or a combination thereof may be combined with the CO2-enriched outlet stream. Any portion of the first gas stream, the second gas stream, or a combination thereof may be compressed. The relative amounts of the first portion of the compressed tail gas stream and the second portion of the compressed tail gas stream may be controlled using a control valve. At least a portion of the tail gas stream may be passed to a tail gas CO2-to-CO conversion system selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit to produce a CO2-enriched effluent stream, and the second CO2-enriched effluent stream may be recycled to the bioreactor.The CO2-enriched outlet stream may comprise an H2:CO:CO2 molar ratio of about 5:1:1, about 4.5:1:1, about 4.33:1:1, about 3:1:1, about 2:1:1, about 1:1:1, or about 1:3:1. The CO2-to-CO conversion system may include at least one of a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit. The at least one fermentation product may be selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol. The first gas stream comprising hydrogen may be produced by a hydrogen production source including at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof. The second gas stream containing CO may be produced by a gas source including at least one of a sugar-based ethanol source, a first-generation corn ethanol source, a second-generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugarbeet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefins source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO source, a natural gas processing source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof. At least one of the C1-fixing bacteria may be selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei.

[0012] The present disclosure also includes an integrated process for the production of at least one fermentation product from a gas stream, the process comprising: obtaining a first gas stream comprising hydrogen and a second gas stream comprising CO; optionally compressing at least a portion of the first gas stream, at least a portion of the second gas stream, or any combination thereof in a first compressor to produce a compressed first gas stream, a compressed second gas stream, and / or a combination of the compressed first gas stream and the second gas stream; and optionally compressing at least a portion of the first gas stream, or the compressed first gas stream, or both, at least a portion of the second gas stream, or the compressed second gas stream, or both, or ii) the compressed first gas stream. the combined CO2-enriched outlet stream and a second gas stream in a gas processing zone comprising a gas component removal unit, a gas desulfurization / acid gas removal unit, or both, to produce a treated stream; converting CO2 in at least a first portion of the treated stream to form CO2 in a CO2-to-CO2 conversion system operating under conditions to produce a CO2-enriched outlet stream; fermenting the CO2-enriched outlet stream in a bioreactor having a culture of one or more C1-fixing bacteria to produce at least one fermentation product stream and a bioreactor tail gas stream; and recycling the tail gas stream to the first compressor, the first gas stream, the second gas stream, or a combination of the first and second gas streams. The CO2-enriched outlet stream may be combined with at least a portion of the treated stream, or the first gas stream, or the second gas stream, or a combination of the first and second gas streams, or the compressed first gas stream, or the compressed second gas stream, or a combination of the compressed first and second gas streams, or any combination thereof. At least a portion of the tail gas stream may be passed to a tail gas CO2-to-CO conversion system selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit to produce a CO2-enriched effluent stream, and the second CO2-enriched effluent stream may be recycled to the bioreactor.The CO2-enriched outlet stream may further comprise hydrogen and CO2 and may comprise an H2:CO:CO2 molar ratio of about 5:1:1, about 4.5:1:1, about 4.33:1:1, or about 3:1:1, about 2:1:1, about 1:1:1, or about 1:3:1. The CO2-to-CO conversion system may include at least one of a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit. The gas processing zone may further include a deoxygenation unit, a catalytic hydrogenation unit, an adsorption unit, a thermal oxidizer, or any combination thereof. The at least one fermentation product may be selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol. The first gas stream containing hydrogen may be produced by a hydrogen production source described above, and the second gas stream containing CO2 may be produced by a gas production source described above. At least one of the C1-fixing bacteria may be selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei. The CO2-enriched outlet stream may contain hydrogen, and the process may further include separating hydrogen from the CO2-enriched outlet stream and recycling the separated hydrogen to combine with the tail gas stream or the compressor. The remaining portion of the CO2-enriched outlet stream may be compressed after separation of the hydrogen. The tail gas stream may comprise methane, and the process further includes passing a portion of the tail gas stream through a methane conversion unit to produce a methane conversion unit effluent and combining the methane conversion unit effluent with the tail gas stream. An oxygen-containing stream may be generated from an oxygen source and passed to the methane conversion unit. A second gas stream comprising hydrogen may be passed to the bioreactor from a hydrogen source, a second gas stream comprising CO from a CO source may be passed to the bioreactor, or both.The second gas stream containing hydrogen from the hydrogen source may be passed to the bioreactor or combined with the CO2-enriched outlet stream, and the second gas stream containing CO2 from the CO2 source may be passed to the bioreactor or combined with the CO2-enriched outlet stream, or any combination thereof. Combining the second gas stream containing hydrogen from the hydrogen source with the CO2-enriched outlet stream, or combining the second gas stream containing CO2 from the CO2 source with the CO2-enriched outlet stream, or both, may be achieved by mixing in a mixer. The ratio of the second gas stream containing hydrogen from the hydrogen source to the CO2-enriched outlet stream entering the bioreactor may be about 0:1 to about 4:1. The CO2-to-CO2 conversion system may include a fired heater having a burner, and at least a portion of the tail gas stream is recycled to at least the burner of the fired heater. The CO2-to-CO2 conversion system may include a steam generator to generate steam, a water knockout unit to generate a water stream, or both. A portion of the CO2-enriched outlet stream may be passed to the inoculator reactor, the buffer tank, or both, or the passing may be directly to the inoculator reactor, the buffer tank, or both without an intervening unit. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 shows a flow scheme of an embodiment in which at least a portion of the tail gas from the bioreactor is passed through a gas component removal unit, compressed, and then recycled to the bioreactor, the CO to CO conversion system, or both. [Figure 2] FIG. 2 shows a flow scheme in which at least a portion of the tail gas from the bioreactor is recycled back to the bioreactor. [Figure 3] FIG. 3 shows a flow scheme of an embodiment in which at least a portion of the tail gas from the bioreactor is compressed and passed through a gas desulfurization / acid gas removal unit before being recycled to the CO to CO conversion system. [Figure 4]4 shows a flow scheme of an embodiment in which at least a portion of the tail gas from the bioreactor is compressed and passed to an optional controller to split the tail gas stream, optionally recycling a portion to the bioreactor while passing the remaining portion of the tail gas through a gas processing zone. The effluent of the gas processing zone is recycled to a CO2 to CO conversion system or upstream of a CO2 to CO conversion system. [Figure 5] FIG. 5 shows a flow scheme of an embodiment similar to that of FIG. 4 with an additional compressor upstream of the CO2 to CO conversion system. [Figure 6] 6 shows a flow scheme of an embodiment in which at least a portion of the tail gas stream is recycled to a compressor upstream of the gas processing zone and the CO2 to CO conversion system. The compressor operates with a combination of a first gas stream comprising hydrogen and a second gas stream comprising CO2. [Figure 7] Figure 7 shows a flow scheme of an embodiment similar to that of Figure 6, except that the compressor operates only on the second gas stream comprising CO2 and not on the first gas stream comprising hydrogen. The first gas stream comprising hydrogen is added to the input stream of the gas processing zone, the effluent, or both. [Figure 8] 8 shows a flow scheme in which the compressor operates on only a portion of the second gas stream containing CO2 and not the first gas stream containing hydrogen, with the remainder of the second gas stream containing CO2 not being compressed and being combined with the first gas stream containing hydrogen. [Figure 9] Figure 9 shows a flow scheme of an embodiment similar to that shown in Figure 7, with the addition of separating a hydrogen-containing stream from the CO2-to-CO conversion system's CO2-enriched outlet stream. The separated hydrogen-containing stream may be combined with tail gas recycle. [Figure 10] FIG. 10 shows a flow scheme of an embodiment similar to that of FIG. 9 with the addition of a second compressor operating on the remaining portion of the CO2-rich outlet stream after the hydrogen-containing stream has been separated from the CO2-rich outlet stream. [Figure 11]FIG. 11 shows a flow scheme of an embodiment similar to that of FIG. 6 , with the addition that at least a portion of the bioreactor tail gas is passed through a methane conversion unit and combined with the bioreactor tail gas and returned through the effluent of the methane conversion unit. An oxygen source may optionally provide an oxygen-containing stream to the methane conversion unit. A second stream containing hydrogen from a hydrogen source may optionally be passed directly to the bioreactor. A second stream containing CO from a CO source may optionally be passed directly to the bioreactor. FIGS. 1-11 further depict an optional embodiment in which at least a portion of the input stream to the CO-to-CO conversion system is bypassed around the CO-to-CO conversion system instead of passing through the CO-to-CO conversion system. The figures also show an optional embodiment in which at least a portion of the tail gas stream is passed through a second CO-to-CO conversion system, and the resulting effluent is passed to the bioreactor. The figure further illustrates an optional embodiment in which at least a portion of the first gas stream comprising H is bypassed around the CO to CO conversion system instead of passing through the CO to CO conversion system. [Figure 12] FIG. 12 shows a flow scheme of an embodiment with more details when the CO2 to CO conversion system is selected to be an rWGS system. [Figure 13] FIG. 13 shows a flow scheme for an embodiment in which a portion of the hydrogen optionally bypasses the CO to CO conversion system, and optionally a portion of the hydrogen is obtained from a second hydrogen source. DETAILED DESCRIPTION OF THE INVENTION

[0014] In gas fermentation processes, the integration of a CO2-to-CO conversion process, particularly the reverse water gas shift process, with a gas production process that generates CO2, such as an industrial process or a syngas process, offers substantial benefits. This integration allows CO2 to be used as a feedstock even if a certain amount of CO2 is required for the fermentation process. The integration of CO2-to-CO conversion allows the feedstock CO2 to be converted to CO in an amount suitable for fermentation or recycled.

[0015] In certain embodiments, the industrial process is selected from ferrous metal product manufacturing, such as steel production, non-ferrous product manufacturing, petroleum refining, power production, carbon black production, paper and pulp manufacturing, ammonia production, methanol production, coke production, petrochemical production, carbohydrate fermentation, cement manufacturing, aerobic digestion, anaerobic digestion, catalytic processing, natural gas extraction, cellulose fermentation, oil extraction, industrial processing of geological reservoirs, processing of fossil resources, such as natural gas, coal, and oil, landfill operations, or any combination thereof. Examples of specific processing steps within industrial processes include catalyst regeneration, fluid catalytic cracking, and catalyst regeneration. Air separation and direct air recovery are other suitable industrial processes. Examples in steel and ferroalloy manufacturing include direct reduction of blast furnace gas, basic oxygen furnace gas, coke oven gas, iron furnace top gas, and residual gas from iron smelting. Other common examples include flue gases from fired boilers and fired heaters, such as natural gas-, oil-, or coal-fired boilers or heaters, and gas turbine exhaust. In these embodiments, the substrate and / or C1 carbon source may be captured from the industrial process before it is released into the atmosphere using any known method.

[0016] The substrate and / or C1 carbon source may be synthesis gas, known as syngas, which may be obtained from reforming, partial oxidation, plasma, or gasification processes. Examples of gasification processes include coal gasification, refinery residue gasification, petroleum coke gasification, biomass gasification, lignocellulosic material gasification, waste wood gasification, black liquor gasification, municipal solid waste gasification, municipal liquid waste gasification, industrial solid waste gasification, industrial liquid waste gasification, waste-to-fuel gasification, sewage gasification, sewage sludge gasification, sludge gasification from wastewater treatment, landfill gasification, biogas gasification, e.g., where biogas is added to enhance the gasification of another material, etc. Examples of reforming processes include steam methane reforming, steam naphtha reforming, natural gas reforming, biogas reforming, landfill gas reforming, coke oven gas reforming, pyrolysis off-gas reforming, ethylene production off-gas reforming, naphtha reforming, and dry methane reforming. Examples of partial oxidation processes include thermal and catalytic partial oxidation processes, catalytic partial oxidation of natural gas, partial oxidation of hydrocarbons, partial oxidation of biogas, partial oxidation of landfill gas, or partial oxidation of pyrolysis off-gas. Examples of municipal solid waste include tires, plastics, refuse-derived fuels, and fibers found in shoes, apparel, textiles, etc. Municipal solid waste may simply be landfill-type waste and may be sorted or unsorted. Examples of biomass may include lignocellulosic material and microbial biomass. Lignocellulosic material may include agricultural waste and forestry waste.

[0017] When discussing recycle herein, references to recycling or passing a stream through a unit are meant to include direct, independent introduction of a stream into a unit, or a combination of a stream with a separate input to a unit.

[0018] A gas production process that produces CO2 is an industrial or syngas process and typically generates an industrial gas or synthesis gas having an effective ratio of CO2 by volume. Additionally, the industrial gas or synthesis gas may contain some amount of CO and / or CH4. A gas production process that produces CO2 is intended to include any industrial or synthesis gas process that produces a CO2 containing gas as a desired end product or as a by-product in the production of one or more desired end products. Exemplary CO2-producing gas production processes include sources including sugar-based ethanol sources, first-generation corn ethanol sources, second-generation corn ethanol sources, sugarcane ethanol sources, sucrose ethanol sources, sugarbeet ethanol sources, molasses ethanol sources, wheat ethanol sources, grain-based ethanol sources, starch-based ethanol sources, cellulosic ethanol sources, cement sources, methanol synthesis sources, olefin sources, steel sources, ferroalloy sources, refinery tail gas sources, secondary combustion gas sources, biogas sources, landfill sources, ethylene oxide sources, methanol sources, ammonia sources, mined CO2 sources, natural gas processing sources, gasification sources, organic waste gasification sources, direct air capture, or ethanol production from any combination thereof. Some examples of steel and ferroalloy sources include blast furnace gas, basic oxygen furnace gas, coke oven gas, direct reduction of iron furnace top gas, electric arc furnace off-gas, and residual gas from iron smelting. Other common examples include flue gases from fired boilers and heaters, such as natural gas, oil, or coal fired boilers or heaters, and gas turbine exhausts.

[0019] FIG. 1 depicts an integrated system having a flexible production platform and process for the production of at least one fermentation product from a gas stream, according to one embodiment of the present disclosure. The process includes receiving a first gas stream containing hydrogen and a second gas stream containing CO, and passing the streams through a CO to CO conversion system. In FIG. 1, the CO to CO conversion system 125 is shown as a reverse water gas shift unit. A hydrogen production source 110 produces a first gas stream 120 containing hydrogen. In one embodiment, the hydrogen production source 110 is a water electrolyzer. A water stream 500 is introduced into the hydrogen production source 110, e.g., at 4.78 kWh / Nm 3 The power source (not shown) may receive power from a power source and convert water into hydrogen and oxygen according to the following stoichiometric reaction:

[0020] H2O + electricity → 2H2 + O2 + heat

[0021] Water electrolysis technologies are known, and exemplary processes include alkaline water electrolysis, proton exchange membrane (PEM) electrolysis, and solid oxide electrolysis. Suitable electrolyzers include alkaline electrolyzers, PEM electrolyzers, and solid oxide electrolyzers. The oxygen-enriched stream 115, which contains oxygen produced as a by-product of water electrolysis, may be used for various purposes. For example, at least a portion of the oxygen-enriched stream 115 may be introduced into the gas production source 220, particularly if the gas production source 220 is selected to be a syngas production process including an oxygen-blown gasifier. Such use of the oxygen-enriched stream 115 reduces the need and associated costs for obtaining oxygen from an external source. As used herein, the term enriched is meant to describe having a higher concentration after a process step compared to before the process step.

[0022] In certain embodiments, the hydrogen production source 110 may be selected from hydrocarbon reforming, hydrogen refining, solid biomass gasification, solid waste gasification, coal gasification, hydrocarbon gasification, methane pyrolysis, refinery tail gas production processes, plasma reforming reactors, partial oxidation reactors, or any combination thereof.

[0023] Gas production source 220 produces second gas stream 140 containing CO from direct air capture, a CO2-generating industrial process, a syngas process, or any combination thereof. First gas stream 120 containing hydrogen and second gas stream 140 containing CO are passed, individually or in combination, to CO2-to-CO conversion system 125 to produce CO-enriched outlet stream 130. The combined gas composition of first gas stream 120 containing hydrogen and second gas stream 140 containing CO2 comprises an H2:CO2 molar ratio of about 3:1 in one embodiment, about 2.5:1 in another embodiment, and about 3.5:1 in yet another embodiment, and the H2:CO molar ratio may be greater than about 5:1. CO2-to-CO conversion system 125 may be at least one unit selected from a reverse water-gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit.

[0024] In certain embodiments, the CO to CO conversion system 125 is a reverse water gas shift unit. Reverse water gas shift (rWGS) technology is known and is used to produce carbon monoxide from carbon dioxide and hydrogen, with water as a by-product. The temperature of the rWGS process is a major factor in the shift occurring. A reverse water gas shift unit can include a single-stage reaction system or two or more reaction stages. Different stages may occur at different temperatures and may use different catalysts.

[0025] In another embodiment, the CO2 to CO conversion system 125 involves a thermal catalytic conversion, which involves breaking stable atomic and molecular bonds of CO2 and other reactants on a catalyst by using thermal energy as the driving force for the reaction to produce CO2. Because the CO2 molecule is thermodynamically and chemically stable, large amounts of energy are required when CO2 is used as the sole reactant. Therefore, other substances, such as hydrogen, are often used as co-reactants to facilitate the thermodynamic process. Many catalysts are known for the process, including metals and metal oxides, as well as nanosized catalytic metal-organic frameworks. Various carbon materials have been used as supports for catalysts.

[0026] In another embodiment, the CO2 to CO conversion system 125 involves partial combustion, where oxygen provides at least a portion of the oxidant requirement for partial oxidation, and the reactants carbon dioxide and water are substantially converted to carbon monoxide and hydrogen.

[0027] In yet another embodiment, the CO2-to-CO conversion system 125 involves plasma conversion, which is a combination of plasma and catalysis, also known as plasma catalysis. Plasma is an ionized gas consisting of electrons, various types of ions, radicals, excited atoms, and molecules, as well as neutral ground-state molecules. The three most common plasma types for CO2-to-CO conversion include dielectric barrier discharge (DBD), microwave (MW) plasma, and gliding arc (GA) plasma. Advantages of selecting plasma conversion for CO2-to-CO conversion include: (i) high process versatility, enabling different types of reactions, such as splitting pure CO2 or converting CO2 in the presence of a hydrogen source (e.g., CH4, H2, or HO); (ii) low investment and operating costs; (iii) no need for rare earth metals; (iv) a convenient modular setup where the plasma reactor scales up linearly with the plant's power output; and (v) easy integration with various types of renewable energy.

[0028] The diagram is drawn when the CO to CO conversion system 125 is selected to include at least one rWGS unit. The rWGS reaction is the reversible hydrogenation of CO to produce CO and HO. Due to its chemical stability, CO is a relatively unreactive molecule, and therefore the reaction to convert it to the more reactive CO is energy intensive.

[0029] CO2+H2⇔ CO+H2O ΔH°298k=+41 kJ mol - 1 (under standard conditions)

[0030] Because the rWGS reaction is endothermic, higher temperatures are thermodynamically favored. Typically, temperatures of about 500°C are desirable to produce significant amounts of CO. In embodiments using higher temperatures, iron-based catalysts are often considered one of the most favorable active metals for higher temperatures due to their thermal stability and high oxygen mobility. In embodiments using lower temperatures, copper is often considered favorable due to its enhanced adsorption of reaction intermediates. In some other embodiments, the rWGS catalyst selection includes Fe / Al2O3, Fe-Cu / Al2O3, Fe-Cs / Al2O3, Fe-Cu-Cs / Al2O3, or combinations thereof.

[0031] The CO2-to-CO conversion system 125 uses, for example, rWGS technology to produce a CO2-enriched outlet stream 130. In some embodiments, the H2:CO molar ratio of the CO2-enriched outlet stream 130 can be greater than about 3:1. Based on the stoichiometry of ethanol as a product and a CO2:CO molar ratio of 1:1, the H2:CO:CO2 molar ratio of the CO2-enriched outlet stream 130 can be about 5:1:1.

[0032] In some instances, the rWGS reaction is operated at a level such that the H:CO molar ratio of the CO-concentrated outlet stream 130 is equal to or less than a predetermined ratio, such as about 3:1. Such CO levels may exceed the CO levels required for gas fermentation. Higher CO conversion than the CO-to-CO conversion system 125 may result in suboptimal performance. Therefore, the size of the CO-to-CO conversion system 125 is designed to be larger than necessary. Such large systems are expensive. Therefore, to avoid such large systems, at least a portion of the first gas stream containing hydrogen is directed to a bypass 520 and not passed to the CO-to-CO conversion system 125. The bypass stream 520 is combined with the CO-concentrated outlet stream 130. Thus, the H:CO ratio in the line 130 delivered for fermentation may be adjusted to be greater than a predetermined ratio in an optimally sized CO-to-CO conversion system 125. Similarly, a portion of the second gas stream 140 containing CO may be diverted to the bypass CO-to-CO conversion system 125 using a second bypass stream 525. In this way, the amount of CO can be controlled without over-engineering the capacity of the CO2 to CO conversion system 125.

[0033] If ethanol is not the intended fermentation product, the stoichiometry described above will be different. For example, if 2,3-butanediol (2,3-BDO) is the intended fermentation product, the H:CO:CO molar ratio in CO-enriched outlet stream 130 will be about 4.5:1:1, based on the stoichiometry of 2,3-BDO, and the CO:CO molar ratio will be 1:1.

[0034] 9H2+2CO+2CO2→C4H 10 O2+4H2O

[0035] If acetone is the intended fermentation product, the H2:CO:CO2 molar ratio of the CO-enriched outlet stream 130 may be about 4.33:1:1, with a CO2:CO molar ratio of 1:1, based on acetone stoichiometry.

[0036] 6.5H2+1.5CO+1.5CO2→C3H6O+3.5H2O

[0037] If acetate is the intended fermentation product, the H2:CO:CO2 molar ratio of the CO-enriched outlet stream 130 may be about 3:1:1 with a CO2:CO molar ratio of 1:1, based on acetate stoichiometry.

[0038] 3H2+1CO+1CO2→C2H4O2+1H2O

[0039] If isopropyl alcohol is the intended fermentation product, the H2:CO:CO2 molar ratio of the CO-enriched outlet stream 130 may be about 5:1:1, with a CO2:CO2 molar ratio of 1:1, based on the stoichiometry of isopropyl alcohol.

[0040] H2+1.5CO+1.5CO2→C3H8O+3.5H2O

[0041] The CO2-enriched outlet stream 130 is passed to a bioreactor 142 containing a culture of one or more C1-fixing bacteria. The bioreactor 142 may be a fermentation system consisting of one or more vessels and / or columns or piping arrangements. Examples of bioreactors include continuous stirred tank reactors (CSTRs), immobilized cell reactors (ICRs), trickle-bed reactors (TBRs), bubble columns, gas-lift fermentors, static mixers, recirculating loop reactors, membrane reactors such as hollow fiber membrane bioreactors (HFM BRs), or other devices suitable for gas-liquid contact. The bioreactor 142 may include multiple reactors or stages, either in parallel or in series. The bioreactor 142 may be a production reactor where the majority of the fermentation product is produced.

[0042] The bioreactor 142 contains a culture of one or more C1-fixing microorganisms capable of producing one or more products from a C1 carbon source. "C1" refers to a one-carbon molecule, such as CO or CO2. A "C1 carbon source" refers to a one-carbon molecule that serves as a partial or sole carbon source for the microorganism. For example, a C1 carbon source can include one or more of CO, CO2, or CH2O2. In some embodiments, a C1 carbon source can include one or both of CO2 and CO2. Typically, the C1-fixing microorganisms are C1-fixing bacteria. In one embodiment, the microorganisms are derived from the C1-fixing microorganisms identified in Table 1. The microorganisms may be classified based on functional characteristics. For example, the microorganisms may be derived from C1-fixing microorganisms, anaerobes, acetogens, ethanologens, and / or carboxydotrophs. Table 1 provides a representative list of microorganisms and identifies the functional characteristics of the microorganisms.

[0043] [Table 1-1] [Table 1-2]

[0044] An "anaerobe" is a microorganism that does not require oxygen for growth. Anaerobes may react negatively or die if oxygen is present above a certain threshold. Typically, the microorganism is an anaerobe. In a preferred embodiment, the microorganism is derived from an anaerobe identified in Table 1.

[0045] An "acetogen" is a microorganism that produces or is capable of producing acetate or acetic acid as a product of anaerobic respiration. Typically, acetogens are obligate anaerobic bacteria that use the Wood-Ljungdahl pathway as their primary mechanism for energy conservation and for the synthesis of acetyl-CoA and acetyl-CoA-derived products such as acetate (Ragsdale, Biochim Biophys Acta, 1784: 1873-1898, 2008). Acetogens use the acetyl-CoA pathway as (1) a mechanism for the reductive synthesis of acetyl-CoA from CO2, (2) a terminal electron acceptor, an energy-saving process, and (3) a mechanism for the fixation, or assimilation, of CO2 in the synthesis of cellular carbon (Drake, Acetogenic Prokaryotes, In: The Prokaryotes, 3rd edition, p. 354, New York, NY, 2006). All naturally occurring acetogens are C1-fixing, anaerobic, autotrophic, and non-methanotrophic. In one embodiment, the microorganisms in bioreactor 142 are acetogens. In other embodiments, the microorganisms are derived from the acetogens identified in Table 1.

[0046] The microorganism may be a species belonging to the genus Clostridium. In one embodiment, the microorganism of the present disclosure is derived from the Clostridia cluster, which includes the species Clostridium autoethanogenum, Clostridium ljungdahlii, and Clostridium ragsdalei. These species were first reported and characterized by Abrini, Arch Microbiol, 161: 345-351, 1994 (Clostridium autoethanogenum), Tanner, Int J System Bacteriol, 43: 232-236, 1993 (Clostridium ljungdahlii), and Huhnke, WO 2008 / 028055 (Clostridium ragsdalei). The microorganism of the present disclosure may also be derived from an isolate or mutant of Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei. Isolates and mutants of Clostridium autoethanogenum include JA1-1 (DSM10061) (Abrini, Arch Microbiol, 161: 345-351, 1994), LBS1560 (DSM19630) (WO 2009 / 064200), and LZ1561 (DSM23693).Isolates and mutants of Clostridium ljungdahlii include ATCC 49587 (Tanner, Int J Syst Bacteriol, 43: 232-236, 1993), PETCT (DSM13528, ATCC 55383), ERI-2 (ATCC 55380) (U.S. Patent No. 5,593,886), C-01 (ATCC 55988) (U.S. Patent No. 6,368,819), 0-52 (ATCC 55989) (U.S. Patent No. 6,368,819), and OTA-1 (Tirado-Acevedo, Production of bioethanol from synthetic gas using Clostridium ljungdahlii, PhD thesis, North Carolina State University, 2010). Isolates and mutants of Clostridium ragsdalei include PI 1 (ATCC BAA-622, ATCC PTA-7826) (WO 2008 / 028055).

[0047] The microorganisms of the present disclosure can be cultured to produce one or more products. For example, Clostridium autoethanogenum has been shown to produce ethanol (WO 2007 / 117157), acetate (WO 2007 / 117157), butanol (WO 2008 / 115080 and WO 2012 / 053905), butyrate (WO 2008 / 115080), 2,3-butanediol (WO 2009 / 151342), lactate (WO 2011 / 112103), butene (WO 2012 / 024522), butadiene (WO 2012 / 024522), methyl ethyl ketone (2-butanone) (WO 2012 / 024522 and WO 2013 / 185123), ethylene (WO 2012 / 026833), acetone (WO 2012 / 115527), isopropanol (WO 2012 / 115527), lipids (WO 2013 / 036147), 3-hydroxypropionate (3-HP) (WO 2013 / 180581), isoprene (WO 2013 / 180584), fatty acids (WO 2013 / 191567), 2-butanol (WO 2013 / 185123), 1,2-propanediol (WO 2014 / 0369152), and 1-propanol (WO 2014 / 0369152). In addition to one or more target products, the microorganisms of the present disclosure may also produce ethanol, acetate, and / or 2,3-butanediol. In certain embodiments, the microbial biomass itself may be considered a product.

[0048] Cultures are generally maintained in an aqueous medium containing sufficient nutrients, vitamins, and / or minerals to allow growth of the microorganism. The aqueous medium may be an anaerobic microbial medium, such as a minimal anaerobic microbial growth medium. Suitable media are known in the art.

[0049] The culture and / or fermentation may desirably be carried out under conditions appropriate for the production of the target product. Typically, the culture / fermentation is carried out under anaerobic conditions. Reaction conditions to consider include pressure (or partial pressure), temperature, gas flow rate, liquid flow rate, medium pH, medium redox potential, agitation rate (if using a continuous stirred tank reactor), inoculation level, maximum gas substrate concentration to ensure that the gas in the liquid phase does not become limiting, and maximum product concentration to avoid product inhibition. Specifically, the rate of substrate introduction may be controlled to ensure that the concentration of gas in the liquid phase does not become limiting, as the product may be consumed by cultivation under gas-limited conditions.

[0050] Operating a bioreactor at elevated pressure allows for an increased rate of gas mass transfer from the gas phase to the liquid phase. Therefore, it is generally preferable to conduct the culture / fermentation at a pressure higher than atmospheric pressure. Furthermore, since a given gas conversion rate is in part a function of the substrate retention time, the conversion rate dictates the required bioreactor volume. The use of a pressurized system can significantly reduce the required bioreactor volume and, consequently, the capital cost of the culture / fermentation equipment. This means that the retention time, defined as the liquid volume in the bioreactor divided by the input gas flow rate, can be reduced when the bioreactor is maintained at a pressure higher than atmospheric pressure. Optimal reaction conditions depend in part on the particular microorganism used. However, it is generally preferable to conduct the fermentation at a pressure higher than atmospheric pressure.

[0051] The target product may be separated from the fermentation broth using any method or combination of methods known in the art, including, for example, fractional distillation, evaporation, pervaporation, gas stripping, phase separation, and extractive separation, including, for example, liquid-liquid extraction. In certain embodiments, the target product is recovered from the fermentation broth by first separating the microbial cells from the broth, then continuously removing a portion of the broth from the bioreactor, separating the target product from the aqueous remainder. Alcohol and / or acetone may be recovered, for example, by distillation. Acids may be recovered, for example, by adsorption on activated carbon. The separated microbial biomass may be recycled to the bioreactor. The solution remaining after the target product has been removed may also be recycled to the bioreactor. Additional nutrients may be added to the recycled solution to replenish the medium before it is returned to the bioreactor.

[0052] The CO2-enriched outlet stream 130 is introduced into a bioreactor 142 and fermented to produce a tail gas stream 160 and a fermentation product stream 150, which may contain any of the products described above. The term tail gas refers to the gases and vapors typically released to the atmosphere from an industrial process after all reactor and processing has taken place. The tail gas stream 160 is ultimately recycled and combined with the CO2-containing second gas stream 140 for introduction into the CO2-to-CO2 conversion system 125. The tail gas stream 160 may contain some CO2 produced during fermentation, for example, by reactions.

[0053] 6CO + 3H2O → C2H5OH + 4CO2 (ΔG° = -224.90 kJ / mol ethanol)

[0054] Recycling the CO2 present in the tail gas stream 160 of the CO2-to-CO conversion system 125 from the bioreactor 142 increases the carbon dioxide recovery efficiency of the overall process. The CO2-depleted tail gas stream 160 may contain less than about 5 mol% CO. In some embodiments, the H2:CO2 molar ratio of the tail gas stream 160 is about 3:1 or less.

[0055] The tail gas stream 160 may contain various components that are best removed before further processing. In these examples, the tail gas stream 160 may have one or more components removed to produce a desulfurized and / or acid gas treated tail gas stream 340, which may be combined with the CO2-containing second gas stream 140. The one or more components that may be removed from the tail gas stream 160 may include sulfur-containing compounds (including but not limited to hydrogen sulfide (HS), carbon disulfide, and / or sulfur dioxide), aromatic compounds, alkynes, alkenes, alkanes, olefins, nitrogen compounds, phosphorus-containing compounds, particulate matter, solids, oxygen, oxygenates, halogenated compounds, silicon-containing compounds, carbonyls, metals, alcohols, esters, ketones, peroxides, aldehydes, ethers, tars, methanethiol, ammonia, diethylamine, triethylamine, acetic acid, methanol, ethanol, propanol, butanol, and higher alcohols, naphthalene, or combinations thereof. These components may be removed by conventional removal modules known in the art, such as a hydrolysis module, an acid gas removal module, a deoxygenation module, a catalytic hydrogenation module, a particulate removal module, a chloride removal module, a tar removal module, and / or a hydrogen cyanide removal module, and combinations thereof. In certain examples, at least one component removed from the tail gas stream includes sulfur-containing compounds, such as hydrogen sulfide, which may be produced, introduced, and / or concentrated by a fermentation process. Hydrogen sulfide may be a catalyst inhibitor in a CO to CO system 125 using rWGS technology and a catalyst.

[0056] Tail gas stream 160 is passed through gas component removal unit 170. Gas component removal unit 170 removes components other than sulfur-containing compounds or acid gas components. In some embodiments, the removed component is water. Because the water-gas shift reaction produces water, it is advantageous to limit the amount of water fed to the water-gas shift reactor. Removing water improves the water balance throughout the process. In some embodiments, the removed component is a hydrocarbon. Gas component removal unit 170 may include multiple sub-modules to remove components other than sulfur-containing compounds. In some embodiments, a liquid scrubber is used to remove other soluble components and ethanol, including higher alcohols. In these embodiments, gas component removal unit 170 may operate to capture and recover fermentation products contained in tail gas stream 160. Volatile organic compounds may also be removed in gas component removal unit 170. Other components that may be removed in gas component removal unit 170 include, for example, mono-nitrogen species, such as hydrogen cyanide (HCN), ammonia (NH), nitrogen oxides (NO), and the like. x ), as well as other known enzyme-inhibiting gases such as acetylene (C2H2), ethylene (C2H4), ethane (C2H6), BTEX (benzene, toluene, ethylbenzene, xylene), and / or oxygen (O2).

[0057] The resulting treated tail gas stream 185 is passed to a first compressor 190 to produce a compressed treated gas stream 200, which is passed to the gas desulfurization / acid gas removal unit 180. In some embodiments, the compressor 190 may be located upstream of the gas component removal unit 170, between the bioreactor 142 and the gas component removal unit 170, to compress the tail gas stream 160 before passing to the gas component removal unit 170. Typically, the compressor 190 operates at a pressure of from about 3 Barg to about 10 Barg. The compressed treated tail gas stream 200 is passed to the gas desulfurization / acid gas removal unit 180 to produce a desulfurized and / or acid gas treated tail gas stream 340. The gas desulfurization / acid gas removal unit 180. Sulfur-containing compounds and / or acid gases are removed because they act as inhibitors in the CO to CO conversion system 125 using rWGS technology by suppressing the activity of the rWGS catalyst. Many commercial desulfurization technologies cannot efficiently remove sulfur in the form of COS, but can better handle sulfur in the form of hydrogen sulfide. In one embodiment, the gas desulfurization / acid gas removal unit 180 operates to convert compounds such as carbonyl sulfide, COS, to hydrogen sulfide, HS, by hydrolysis according to the following reaction:

[0058] COS+H2O⇔H2S+CO2

[0059] Hydrolysis can be accomplished with a metal oxide or alumina catalyst to convert COS to HS. In some embodiments, more than one desulfurization operation may be used, for example, iron sponge followed by a metal oxide catalyst. In certain other embodiments, the gas desulfurization / acid gas removal unit 180 may remove hydrogen sulfide using a zinc oxide (ZnO) catalyst. In other embodiments, pressure swing adsorption (PSA) is utilized to remove acid gases by adsorption through a suitable adsorbent in a fixed bed contained within a vessel under high pressure. In still other embodiments, caustic washing is used for gas desulfurization. Caustic washing may include passing the compressed treated tail gas stream 200 through a caustic solution, such as NaOH, to remove sulfur-containing compounds. Hydrogen sulfide removal by caustic washing may be expressed as follows:

[0060] H2S(g)+NaOH(aq)→NaHS(aq)+H2O NaHS(aq)+NaOH(aq)→Na2S(aq)+H2O

[0061] The desulfurized and / or acid gas treated tail gas stream 340 exiting the gas desulfurization / acid gas removal unit 180 may be combined with the second gas stream 140 containing CO and recycled to the CO to CO conversion system 125. Alternatively, instead of passing the desulfurized and / or acid gas treated tail gas stream 340 to be combined with the second gas stream 140 containing CO, an alternative desulfurized and / or acid gas treated tail gas stream 345 is combined with the first gas stream 120 containing hydrogen.

[0062] A portion of the compressed treated tail gas stream 200 may be combined with the CO2-enriched outlet stream 130 and passed to the bioreactor 142 instead of being passed to the gas desulfurization / acid gas removal unit 180. Such recirculation benefits the growth of the microorganisms as they consume sulfur to produce amino acids, such as methionine and cysteine. As a result, the sulfur dosage requirements to the bioreactor 142 are reduced by recirculating the sulfur as part of the compressed treated tail gas stream 200.

[0063] In an optional embodiment in which gas production source 220 includes the production of biogas, a portion of second gas stream 140 containing CO is passed to optional biogas reformer 230. Biogas refers to gas produced by the anaerobic digestion of organic matter such as manure, sewage sludge, municipal solid waste, biodegradable waste, or any other biodegradable feedstock. Biogas consists primarily of methane and carbon dioxide. Typically, a biogas reformer combines steam reforming of CO and methane to produce a syngas stream.

[0064] CH4+CO2⇔2CO+2H2ΔH°=247kJ / mol CH4+H2O⇔CO+3H2ΔH°=206kJ / mol

[0065] With reference to FIG. 1, biogas reformer effluent stream 240 containing CO and H produced in biogas reformer 230 may be combined with CO-enriched outlet stream 130 and operate to improve the H:CO ratio for many fermentation processes.

[0066] In one embodiment, at least a portion of tail gas stream 160 is passed through an optional second CO2-to-CO conversion system 510, which may be a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit. Tail gas stream 160 may be CO-depleted but have residual H and CO2. Passing at least a portion of tail gas stream 160 through optional second CO2-to-CO conversion system 510 and recycling second CO2-to-CO conversion system effluent 512 to bioreactor 142 may reduce the H2:CO ratio in bioreactor 142. This reduction in the H2:CO ratio in bioreactor 142 may benefit product selectivity and result in increased or more rapid microbial growth. It is noted that second CO2-to-CO conversion system effluent 512 may be recycled for combination with stream 130 instead of being passed independently to bioreactor 142 (not shown).

[0067] In one embodiment, an optional additional stream containing hydrogen 430 produced from the hydrogen production source 110 is passed to the bioreactor 142 or the CO2-enriched outlet stream 130, thus bypassing the CO2-to-CO2 conversion system 125. The additional stream containing hydrogen 430 may be passed without an intervening processing unit. Microbial fermentation of CO2 in the presence of H2 can result in substantially complete carbon transfer to products such as alcohol, but in the absence of sufficient H2, only a portion of the available CO2 is converted to products, while another portion is converted to CO2 via the following equation: 6CO2 + 3H2O → C2H5OH + 4CO2. Therefore, providing sufficient hydrogen to the bioreactor 142 can be beneficial in some embodiments. Employing a bypass for the additional stream containing hydrogen 430 to be passed to the bioreactor 142 or the CO2-enriched outlet stream 130 without passing it through the CO2-to-CO2 conversion system 125 allows for control of the amount of hydrogen directed to the units at different points in the overall process run. For example, during start-up, a bioreactor, including any inoculator, may require less hydrogen, thereby benefiting from a CO2-rich feed during start-up. However, toward the end of a run, a bioreactor may require less CO2, and a greater relative amount of H2 may be used. This can be particularly beneficial during the turndown or inoculation phase (where the primary bioreactor receives less CO2 than the inoculation bioreactor), or when using a buffer tank. The bypass allows control to vary the H2:CO ratio of the feed to the CO2-to-CO conversion system 125, to the bioreactor 142, or both. The bypass also allows control to vary the H2:C (hydrogen:carbon) to the CO2-to-CO conversion system 125, to the bioreactor 142, or both.

[0068] Providing a CO2-rich environment to the bioreactor 142 through the use of the CO2 to CO2 conversion system 125 and recirculation of CO2 from the bioreactor 142 to the CO2 to CO2 conversion system 125 can be beneficial for improved product selectivity in a gas environment with a high proportion of CO2. One such example is the production of ethanol. Another benefit is that microbial growth of certain microorganisms that have the Wood-Ljungdahl pathway may be increased because the biological water-gas shift of the Wood-Ljungdahl pathway is improved when these microorganisms consume higher concentrations of CO2.

[0069] 2 shows an integrated system for the production of at least one fermentation product from a gas stream according to another embodiment of the present disclosure. A hydrogen production source 110 produces a first gas stream 120 comprising hydrogen. A gas production source 220, which may be direct air recovery or an industrial process producing CO, produces a second gas stream 140 comprising CO. The first gas stream 120 comprising hydrogen and the second gas stream 140 comprising CO are combined to form a combined feed stream 250, which is passed to a CO to CO conversion system 125. The gas composition within combined feed stream 250 comprises an H:CO molar ratio of greater than about 3:1 in one embodiment, greater than about 2.5:1 in another embodiment, greater than about 3.5:1 in yet another embodiment, and greater than about 5:1 in yet yet another embodiment.

[0070] In one embodiment, CO2-to-CO conversion system 125 employs rWGS technology. In CO2-to-CO conversion system 125, CO2 is reacted to produce CO2-enriched outlet stream 130. The molar ratio of the components in the stream is as discussed in FIG. 1. As shown in FIG. 2, in one embodiment, at least a portion of feed stream 250 is optionally diverted around CO2-to-CO conversion system 125 in bypass stream 520. Bypass stream 520 is combined with CO2-enriched outlet stream 130. The benefits of bypass stream 520 are as described in FIG. 1. CO2-enriched outlet stream 130 is passed to bioreactor 142 having a culture of one or more C1-fixing microorganisms. The culture is fermented to produce one or more fermentation products 150 and tail gas stream 160. CO2-depleted tail gas stream 160 may contain less than about 5 mol% CO. In some embodiments, the H2:CO2 molar ratio of tail gas stream 160 is about 3:1 or less.

[0071] Tail gas stream 160 is passed to a first compressor 190 to produce a compressed tail gas stream 202. Compressed tail gas stream 202 is recycled for combination with CO2-enriched outlet stream 130. Optionally, a small first purge stream 204 of tail gas stream 160 or a small second purge stream 206 of compressed tail gas stream 202 may be removed to control the buildup of nitrogen, methane, argon, helium, or other inert components.

[0072] 1, in one embodiment, at least a portion of tail gas stream 160 is passed through an optional second CO2-to-CO2 conversion system 510, and second CO2-to-CO2 conversion system effluent 512 is recycled to bioreactor 142 or to a CO2-concentrated outlet stream. Also as in FIG. 1, second CO2-to-CO2 conversion system effluent 512 may be recycled to be combined with stream 130 instead of being passed separately to bioreactor 142 (not shown).

[0073] Figure 3 shows another embodiment similar to Figure 2, except that compressed tail gas stream 202 is passed to gas desulfurization / acid gas removal unit 180 and the resulting desulfurized and / or acid gas treated tail gas stream 340 is passed to CO2-to-CO conversion system 125. The gas compositions in combined feed stream 250, in CO2-enriched outlet stream 130 and tail gas stream 160 are as described in Figures 1 and 2. Optional bypass-related embodiments are as described in Figure 2.

[0074] Figure 4 shows another embodiment similar to Figures 2 and 3. Tail gas stream 160 is passed to first compressor 190, and the resulting compressed tail gas stream 202 is passed to optional control valve 550. Optional control valve 550 is used to control the relative portion of compressed tail gas stream 202 that is directed to gas processing zone 182 or combined with CO2-enriched outlet stream 130. Gas processing zone 182 is shown as including gas component removal unit 170 and gas desulfurization / acid gas removal unit 180. However, both units are not required in all embodiments, and gas processing zone 182 may include only one of gas component removal unit 170 or gas desulfurization / acid gas removal unit 180. Furthermore, the units in gas processing zone 182 may be in any order. Treated tail gas stream 185 produced from gas processing zone 182 is added to combined feed stream 250 and passed to CO2-to-CO conversion system 125. Optional control valve 550 may be adjusted to split compressed tail gas stream 202 in different proportions based on the current phase of fermentation. For example, during the start-up fermentation stage, an increase in CO demand within bioreactor 142 may be achieved by adjusting control valve 550 to flow more compressed tail gas stream 202 and combine it with CO2-enriched outlet stream 130 than gas processing zone 182. On the other hand, once fermentation in bioreactor 142 transitions to a steady phase, a decrease in CO2 demand within bioreactor 142 may be achieved by adjusting control valve 550 to decrease the flow rate of compressed tail gas stream 202 and combine it with CO2-enriched outlet stream 130 than gas processing zone 182. In another example, when H2 utilization during fermentation is low, e.g., less than 70%, control valve 550 may be adjusted to flow more compressed tail gas stream 202 and combine it with CO2-enriched outlet stream 130 than gas processing zone 182. As shown, a control valve 550 is used to achieve dynamic control of the H2:CO ratio provided to the bioreactor 142 based on the CO and / or H2 requirements during fermentation.

[0075] The gas composition is described in relation to FIGS. 2 and 3, with optional bypass embodiments as described in FIG.

[0076] Figure 5 is similar to Figure 4 with the addition of a second compressor 192. The combined feed stream 250 is passed to the second compressor 192 to produce a compressed combined feed stream 260. The gas composition of the combined feed stream 260 is as described above. The compressed combined feed stream 260 is combined with the treated tail gas stream 185 and passed to the CO2-to-CO conversion system 125 to produce the CO2-enriched outlet stream 130. The gas compositions of the CO2-enriched outlet stream 120 and the tail gas stream 160 are as described above. The optional control valve 550 and bypass embodiments are as described above.

[0077] FIG. 6 illustrates an embodiment in which both the combined feed stream 250 and the tail gas stream 160 are passed to a first compressor 190. The first compressor 192 provides a compressed stream 270 that is passed to the gas processing zone 182. The gas processing zone is as described above. Of course, some gas processing modules may be added or removed from the gas processing zone 182 based on the actual gas composition. For example, in some embodiments, the compressed stream 270 may contain acetylene (C2H2), which can act as a microbial inhibitor in fermentation. To remove acetylene, a catalytic hydrogenation module can be included in the gas processing zone 182. Catalytic hydrogenation involves adding hydrogen in the presence of a hydrogenation catalyst, such as one containing nickel, palladium, or platinum. The choice of hydrogenation catalyst depends on the specific gas composition and operating conditions of the system. In certain embodiments, palladium on alumina (Pd / Al2O3) is used as the catalyst. An example of such a catalyst is BASF™ R0-20 / 47. In other embodiments, the gas composition of compressed stream 270 may include benzene, ethylbenzene, toluene, and xylenes (BETX), which may inhibit fermentation. Therefore, a BETX removal module may be added to gas treatment zone 182. An exemplary BETX removal module may involve adsorption of BETX components using one or more activated carbon beds. Another exemplary BTEX removal module includes vent gas incineration, which is a thermal oxidation process in which BTEX components are combusted at temperatures above about 650°C. Treated stream 290 is passed to CO2 to CO conversion system 125. The gas compositions of the various streams are shown above. Bypass embodiments are described above.

[0078] 7 is similar to FIG. 6 , except that the first gas stream 120 comprising hydrogen may already be pressurized by the hydrogen source 110 and therefore does not need to be passed to the first compressor 190. The first gas stream 120 comprising hydrogen may be combined with the second gas stream 140 comprising CO before, after, or both before and after the gas processing zone 182 without being passed through the first compressor 190. The gas composition in gas stream 290 prior to introduction into the CO to CO conversion system 125 comprises an H:CO molar ratio of about 3:1 in one embodiment, about 2.5:1 in another embodiment, about 3.5:1 in yet another embodiment, and greater than about 5:1 in yet another embodiment. The gas compositions of the CO-enriched outlet stream 130 and the tail gas stream 160 are as described above.

[0079] FIG. 7 also illustrates an embodiment in which, regardless of the pressure provided by the hydrogen source 110, the first gas stream 120 containing hydrogen is optional and cannot be used in lieu of employing a stream containing hydrogen 430 produced from the hydrogen production source 110 that does not pass through the CO2-to-CO2 conversion system 125. The additional stream containing hydrogen 430 may be passed to the bioreactor 142 or combined with the CO2-enriched outlet stream 130. If desired, the stream containing hydrogen 430 produced from the hydrogen production source 110 may be compressed to a target pressure. Separating the CO2 supply from the H2 supply allows for increased control over the amount of hydrogen directed to the bioreactor 142 at different points throughout the process run. For example, during start-up, a bioreactor containing any inoculator may require less hydrogen, thereby benefiting from a CO2-rich supply during start-up. However, toward the end of the run, less CO2 may be required in the bioreactor, and a greater relative amount of H2 may be used. This can be particularly beneficial during a turndown or inoculation phase (where the main bioreactor receives less CO than the inoculation bioreactor), or when using a buffer tank. The bypass allows the control to vary the H:CO ratio of the feed to the CO to CO conversion system 125, to the bioreactor 142, or both. A target H:CO:CO ratio for one of the bioreactors could be 1:3:1.

[0080] In FIG. 8 , a portion of the second gas stream 140 containing CO is passed to the first compressor 190, and another portion of the second gas stream 140 containing CO is combined with the first gas stream 120 containing hydrogen and passed to the gas processing zone 182, thereby bypassing the first compressor 190. Some gas production sources 220 may provide oxygen as a component of the second gas stream 140 containing CO. However, for some microorganisms, oxygen may be a microbial inhibitor, and the oxygen content in the second gas stream 140 containing CO may need to be reduced to an acceptable level. In these situations, the gas processing zone 182 may further include a deoxygenation module. The deoxygenation module may employ a catalytic process in which oxygen is reduced to either CO or water. In certain embodiments, the catalyst used in the deoxygenation module includes copper. Examples of such catalysts are BASF PURISTAR® 3.15 or BASF CU 0226S. The deoxygenation process is exothermic, and the heat generated can be used within the overall process, such as to preheat the gas prior to the endothermic reaction in the CO to CO conversion system 125, which includes rWGS technology. The gas compositions of the various streams are as described above. The bypass embodiment is as described above.

[0081] 9 illustrates an embodiment in which the CO2-enriched outlet stream 130 to the CO2-to-CO conversion system 125 is passed through a hydrogen separation unit 330 before being passed to the bioreactor 142. The hydrogen separation unit 330 may involve membrane separation or pressure swing adsorption techniques. Separating hydrogen from the CO2-enriched outlet stream 130 enriches the CO in the H2:CO ratio of the hydrogen separation unit effluent 350, which is passed to the bioreactor 142. The separated hydrogen stream 344 produced in the hydrogen separation unit 330 is recycled separately to the first compressor 190 (not shown) or combined with the tail gas stream 160 and also recycled to the first compressor 190. FIG. 9 illustrates an embodiment in which the hydrogen-containing first gas stream 120 is already at sufficient pressure and therefore bypasses the first compressor 190 and combines with the compressed stream 270 prior to the gas processing zone 182. If the hydrogen-containing first gas stream 120 has not yet been compressed, at least a portion of the hydrogen-containing first gas stream 120 may pass through the first compressor 190. The gas composition of the treated stream 290 prior to introduction into the CO-to-CO conversion system 125 comprises an H:CO molar ratio of about 3:1 in one embodiment, about 2.5:1 in another embodiment, about 3.5:1 in yet another embodiment, and greater than about 5:1 in yet another embodiment. The H:CO gas composition in the CO-enriched outlet stream 130 is as described above. In one embodiment, the gas composition in the hydrogen separation zone effluent 350 comprises an H:CO molar ratio of greater than about 1:1 but not more than about 5:1, and an H:CO:CO molar ratio of about 5:1:1, where ethanol is the product described above, and further as described above for other products. The gas composition of the tail gas stream 160 is as described above. The bypass embodiment is generally as described above.

[0082] Figure 10 is similar to Figure 9 with the addition of hydrogen separation unit effluent compressor 370. When hydrogen separation unit 330 uses pressure swing adsorption, hydrogen separation unit effluent 350 is often at a pressure below that required for bioreactor 142. Hydrogen separation unit effluent compressor 370 provided further compression of the hydrogen separation unit effluent to achieve the pressure required for introduction into bioreactor 142. The gas composition in treated stream 290 prior to introduction into CO2-to-CO conversion system 125 and in CO2-enriched outlet stream 130 is as described above. The gas composition of the hydrogen separation unit effluent prior to introduction into effluent compressor 370 in the hydrogen effluent zone comprises an H2:CO molar ratio greater than about 1:1 but not greater than about 5:1, and the H2:CO:CO2 molar ratio of gas stream 365 may be about 5:1:1 for product ethanol, as described above, and for other products as described above. The gas composition in tail gas stream 160 is as described above. The bypass embodiment is as described above.

[0083] Figure 11 is similar to Figure 6, except that the CO2-enriched outlet stream 130 from the CO2-to-CO conversion system 125 further includes methane, either from the hydrogen source 110 or as a by-product of the CO2-to-CO conversion system 125 including rWGS technology. Over time, methane from either or both of these sources may accumulate in the bioreactor tail gas stream 160. When the methane concentration in the bioreactor tail gas stream 160 increases to a threshold limit, for example, greater than 10 mol%, and perhaps greater than 50 mol%, at least a portion of the tail gas stream 160 is passed to the methane conversion unit 400 as a tail gas purge 390. An optional oxygen source 410 may provide an optional oxygen-containing stream 420 to the methane conversion unit 400. In some embodiments, the oxygen source 410 of the methane conversion unit 400 may be a water electrolyzer, whereby oxygen is a by-product. Methane conversion unit 400 produces at least CO2 by oxidation of methane by the reaction CH4 + 2O2 → CO2 + 2H2O and produces a methane conversion effluent stream 421 containing at least CO2 and further comprising CO and H2, which may be combined with tail gas stream 160 and passed to first compressor 190. Methane conversion unit 400 may be a methane reforming unit, a methane steam reforming unit, a partial oxidation unit, an autothermal reforming unit, an oxidation unit, a combustion unit, a biogas reforming unit, or a gasification unit. When methane conversion unit 400 is involved, it involves steam reforming of methane, represented by the following equation:

[0084] CH4 + H2O (steam) → CO + 3H2 (endothermic)

[0085] The oxygen-containing stream 420 may also be combusted in a heater burner to produce steam or heat a methane conversion unit. The methane conversion unit may involve autothermal reforming (ATR), using oxygen or carbon dioxide as reactants with methane to form synthesis gas. The reaction may occur in a single reactor where methane is partially oxidized. The reaction can be described by the following equation:

[0086] CH4+O2+CO2→3H2+3CO+H2O (using CO2) CH4 + O2 + 2H2O → 10H2 + 4CO (using steam)

[0087] The gas compositions of treated stream 290 and CO2-enriched outlet stream 130 are as described above. The gas composition of tail gas stream 160 or tail gas purge 390 typically contains less than about 5 mol% CO. In some embodiments, the H2:CO2 molar ratio of tail gas stream 160 or tail gas purge 390 is about 3:1 or less, and the accumulated methane is greater than about 5 mol%. Bypass embodiments are as described above.

[0088] In one embodiment, as described above, an optional additional stream including hydrogen 430 produced from the hydrogen production source 110 is passed directly to the bioreactor 142. While microbial fermentation of CO in the presence of H can result in substantially complete carbon transfer to products such as alcohol, in the absence of sufficient H, only a portion of the available CO is converted to products, while another portion is converted to CO via the following equation: 6CO + 3H0 → C2H5OH + 4CO2. Therefore, providing sufficient hydrogen to the bioreactor 142 can be beneficial in some embodiments. In another embodiment, an optional additional stream including CO2 440 produced from the gas production source 220 is passed directly to the bioreactor 142. Such an arrangement can be beneficial for maintaining CO2 partial pressure in the CO2-depleted zone of the bioreactor 142.

[0089] 12 is directed to an embodiment in which CO to CO conversion system 125 is selected to be an rWGS system, and additional equipment of an rWGS system is specifically illustrated. Hydrogen production source 110 and first gas stream 120, gas production source 220 and second gas stream comprising CO, and combined feed stream 250 are all as described above. Gas processing zone 182 and treated stream 290, as well as bioreactor 142, fermentation product stream 150, and tail gas stream 160, are as described above.

[0090] Treated stream 290 is introduced into preheater 560 where it is heated via indirect heat exchange with rWGS reactor effluent 588 to provide preheated stream 562. Preheated stream 562 is passed to electric heater 564 for further heating to produce electrically heated stream 566, which is then further heated in fired heater 568 to produce fully heated stream 570. Different heating modes are employed to maximize the use of available energy to reach the target temperature of the rWGS reactor. Heat from streams that need to be cooled is transferred to streams that need to be heated, and combustible components of the waste are combusted in burners to produce hot streams requiring high temperatures.

[0091] Fully heated stream 570 is introduced into rWGS reactor 571, which can be a single-stage or multi-stage reactor system. In rWGS reactor 571, at least a portion of the CO present in fully heated stream 570 is converted to CO. Thus, rWGS reactor effluent 588 is enriched in CO compared to fully heated stream 570. Because the rWGS reactor effluent is at the temperature of rWGS reactor 571, it contains available heat that can be used to heat another stream and, therefore, is passed to preheater 560 for indirect heat exchange with treated stream 290. Heat-exchanged rWGS reactor effluent 563 is then passed from preheater 560 to heat recovery / steam generator 572 to further recover available heat. Cooling water stream 574 is passed to heat recovery / steam generator 572 to receive the available heat from heat-exchanged rWGS reactor effluent 563 and produce steam stream 576. This may be used elsewhere in the overall process or in another process. The resulting heat-depleted stream 578 is passed to a water knockout unit 580 to produce a stream containing water 584 and a water-depleted stream 582. The steam containing water 584 may be directed to any part of the process or another process requiring water. The water-depleted stream 582 is passed to an air cooler 586 to provide the CO2-enriched outlet stream 130.

[0092] The CO2-enriched outlet stream 130 may be split into portions, with a first portion being passed to optional mixer 590, or if optional mixer 590 is not present, the first portion being passed to bioreactor 142. An optional second portion of the CO2-enriched outlet stream 130 may be passed to another unit, such as a buffer tank (not shown), or to an inoculator reactor, which may or may not be part of bioreactor 142. Having storage of the CO2-enriched outlet stream 130 is advantageous for periods when the supply of the CO2-containing gas stream is reduced. If the hydrogen requirement of the inoculator reactor is low compared to the bioreactor, it may be advantageous to pass the second portion of the CO2-enriched outlet stream 130 to the inoculator before adding any additional hydrogen to the CO2-enriched outlet stream 130. An optional third portion of the CO2-enriched outlet stream 130 may be recycled to fired heater 568 and combusted in a burner of fired heater 568 to provide heat. This embodiment is particularly advantageous during start-up when the bioreactor 142 is not yet on stream for consumption of CO in the CO-enriched outlet stream 130 .

[0093] In some embodiments, it is advantageous to adjust and control the amount of hydrogen provided to bioreactor 142 by providing an additional stream containing hydrogen 430 from hydrogen production source 110 that is passed to mixer 590. In mixer 590, CO2-enriched outlet stream 130 is mixed with hydrogen-containing additional stream 430 to produce bioreactor feed stream 592. The ratio of hydrogen-containing additional stream 430 to CO2-enriched outlet stream 130 from the hydrogen source is between about 0:1 and about 4:1. The bioreactor feed stream is provided to bioreactor 142, and fermentation product stream 150 is produced, as well as bioreactor tail gas stream 160. Bioreactor tail gas stream 160 may be split into portions and recycled to different locations within the process. Where to route the bioreactor tail gas often depends on the current operating conditions of the process. For example, if bioreactor 142 is operated in a mode that produces substantial CO, bioreactor tail gas 160 may be recycled, at least in part, to gas processing zone 182 or CO-to-CO conversion system 125 for CO-to-CO conversion. At any time, a portion of bioreactor tail gas 160 may be fed to the burner of fired heater 568 for combustion and heat generation. This use of at least a portion of bioreactor tail gas 160 for combustion is particularly advantageous in embodiments in which bioreactor tail gas 160 contains methane. It is contemplated that biogas from a wastewater treatment system may be combined with bioreactor tail gas 160 and used for combustion and heat in fired heater 568. It is further contemplated that biogas from a wastewater treatment system may be recycled or recycled directly to the bioreactor.

[0094] 13 is directed to an embodiment in which a separate hydrogen stream does not pass through the CO2 to CO2 conversion system but is mixed downstream of the CO2 to CO2 conversion system to form the feed stream to the bioreactor. The separate hydrogen stream 602 may be obtained from a separate, second hydrogen source 600 (as shown) or may be obtained from hydrogen source 110. The separate hydrogen stream 602 containing hydrogen may be passed to an optional hydrogen stream gas processing zone 603 to produce a treated hydrogen stream 604 containing hydrogen. The hydrogen stream gas processing zone 603 may include a gas component removal unit and / or a gas desulfurization / acid gas removal unit. Both units are not required in all embodiments; the hydrogen gas processing zone 603 may include only one of a gas component removal unit or a gas desulfurization / acid gas removal unit. Furthermore, the units within the hydrogen stream gas processing zone 603 may be in any order. The treated hydrogen gas stream 604 produced from the hydrogen stream gas treatment zone 603 passes through a mixer 590 and is mixed with the treated CO2-enriched outlet stream 186 to produce a bioreactor feed stream 592.

[0095] Hydrogen production source 110, hydrogen-containing first gas stream 120, gas production source 220, CO2-containing second gas stream 140, and combined feed stream 250 are all as described above. Gas processing zone 182 and treated stream 290, as well as CO to CO2 conversion system 125, CO2-enriched outlet stream 130, mixer 590, combined stream 592, bioreactor 142, fermentation product stream 150, and tail gas stream 160, are described above, but may have different ratios of H2 and CO2. Second gas processing zone 183 and third gas processing zone 187 are as described for gas processing zone 182.

[0096] With reference to the first gas stream 120 comprising hydrogen from the hydrogen production source 110 and the second gas stream 140 comprising CO from the gas production source 220, different ratios of hydrogen to CO in the streams are useful at different points in the operation of the overall process. For example, the molar ratio of H in the first gas stream 120 comprising hydrogen to CO in the second gas stream 140 comprising CO (H:CO) can be about 1:1 in one embodiment, about 2:1 in another embodiment, and about 3:1 in yet another embodiment. In an embodiment where the H:CO molar ratio is 1:1, the first gas stream 120 comprising hydrogen can have twice the volume of the separate hydrogen stream 602 obtained from the separate second hydrogen source 600. In an embodiment where the H:CO molar ratio is 2:1, the first gas stream 120 comprising hydrogen can have half the volume of the separate hydrogen stream 602 obtained from the separate second hydrogen source 600. In an embodiment where the H:CO molar ratio is 3:1, the first gas stream containing hydrogen 120 provides all the hydrogen needed, and the separate hydrogen stream 602 obtained from the separate second hydrogen source 600 is not used. Effectively, a different amount of hydrogen may be bypassed through the use of the hydrogen stream 602 / treated hydrogen gas stream 604. In one embodiment, the sum of the hydrogen in the first gas stream containing hydrogen 120 plus the hydrogen in the separate hydrogen stream 602 provides enough hydrogen to produce a 3:1 H:CO molar ratio, with CO being measured in the second gas stream containing CO 140.

[0097] Tail gas stream 160 may be recycled to bioreactor 142 or may be recycled to CO2 to CO2 conversion system 125. Optionally, tail gas stream 160 may pass through a third gas processing zone 187 to produce a treated tail gas stream 185, which may then be passed to CO2 to CO2 conversion system 125. Second gas processing zone 183 may optionally separate a portion of CO2-enriched outlet stream 130, which may be recycled to CO2 to CO2 conversion system 125 as stream 181.

[0098] All references, including publications, patent applications, and patents, cited herein are incorporated by reference as if each reference were individually and specifically indicated to be incorporated by reference. The citation of a reference herein is not an acknowledgment that its prior art forms part of the common general knowledge in the field of endeavor in any country.

[0099] The description of ranges of values ​​herein is intended merely to serve as a shorthand method for individually referring to each individual value falling within the range, unless otherwise indicated herein, and each individual value is incorporated herein as if it were individually recited herein. For example, unless otherwise indicated, any concentration range, percentage range, ratio range, integer range, size range, or thickness range should be understood to include any integer value within the recited range, and, where appropriate, fractions thereof (such as tenths and hundredths of integers). Unless otherwise indicated, ratios are molar ratios and percentages are by weight.

[0100] All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. Any and all examples provided herein, or the use of exemplary language such as "etc.", are intended merely to better illuminate the disclosure and do not limit the scope of the disclosure unless otherwise asserted. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the disclosure.

[0101] Preferred embodiments of the present disclosure are described herein. Variations of these embodiments may become apparent to those skilled in the art upon reading the foregoing description, and the adoption of such variations is intended to be within the scope of the present disclosure, since the present disclosure may be practiced in ways other than as specifically described herein. Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context. The inventions described in the original claims are listed below. [Invention 1] 1. An integrated process for the production of at least one fermentation product from a gas stream, said process comprising: a) a first gas stream comprising hydrogen and CO 2 and a second gas stream comprising: b) operating at least a portion of the first gas stream and at least a portion of the second gas stream under conditions to produce a CO2-enriched outlet stream; 2 and passing it through a CO conversion system. c) passing the CO2-enriched outlet stream through a bioreactor having a culture of one or more C1-fixing bacteria and fermenting the bioreactor to produce at least one fermentation product stream and a bioreactor tail gas stream; d) compressing the bioreactor tail gas stream to produce a compressed bioreactor tail gas stream; e) combining, in any order, at least a first portion of said compressed bioreactor tail gas stream with: i) a gas desulfurization and / or acid gas removal unit; or ii) a gas component removal unit; or ii) passing the gas through both the gas desulfurization and / or acid gas removal unit and the gas component removal unit; producing a compressed treated bioreactor tail gas stream; f) recirculating the compressed treated bioreactor tail gas stream to i) combining with the first gas stream, the second gas stream, or a combination thereof; or ii) the CO 2 to a CO conversion system, or iii) combined with the CO2-enriched outlet stream; or iv) any combination thereof, and g) optionally recycling a second portion of said compressed bioreactor tail gas stream to combine with said CO2-enriched outlet stream or said bioreactor. [Invention 2] 10. The process of claim 1, further comprising combining at least a second portion of the first gas stream, at least a second portion of the second gas stream, or a combination thereof, with the CO2-enriched outlet stream. [Invention 3] 10. The process of claim 1, further comprising passing at least a second portion of the first gas stream, at least a second portion of the second gas stream, or a combination thereof, through the bioreactor. [Invention 4] 10. The process of claim 1, further comprising compressing any portion of the first gas stream, the second gas stream, or a combination thereof. [Invention 5] 2. The process of claim 1, further comprising using a control valve to control the relative amounts of the first portion of the compressed tail gas stream and the second portion of the compressed tail gas stream. [Invention 6] and converting at least a portion of the tail gas stream into CO of the tail gas stream selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit. 2 2. The process of claim 1, further comprising passing the second CO2-enriched eluate stream through a CO2 conversion system to CO to generate a CO2-enriched eluate stream; and recycling the second CO2-enriched eluate stream to the bioreactor. [Invention 7] the CO2-enriched outlet stream is mixed with about 5:1:1, about 4.5:1:1, about 4.33:1:1, or about 3:1:1, about 2:1:1, about 1:1:1, or about 1:3:1 H 2 :CO:CO 2 The process according to claim 1, including a molar ratio. [Invention 8] The CO 2 2. The process of claim 1, wherein the CO to CO conversion system comprises at least one of a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit. [Invention 9] The process according to invention 1, a) the at least one fermentation product is selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol, or b) the first gas stream comprising hydrogen is produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof; or c) the CO 2 the second gas stream comprising a sugar-based ethanol source, a first generation corn ethanol source, a second generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugar beet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefin source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO 2 or is produced by a gas production source, including at least one of a natural gas processing production source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof; d) The process according to invention 1, any combination thereof. [Invention 10] 2. The process according to claim 1, wherein the at least one C1-fixing bacterium is selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei. [Invention 11] 1. An integrated process for the production of at least one fermentation product from a gas stream, said process comprising: a) a first gas stream comprising hydrogen and CO 2 and a second gas stream comprising: b) optionally compressing in a first compressor at least a portion of the first gas stream, at least a portion of the second gas stream, or any combination thereof, to produce a compressed first gas stream, a compressed second gas stream, and / or a combination of compressed first and second gas streams; c) i) at least a portion of the first gas stream or the compressed first gas stream, or both, and at least a portion of the second gas stream or the compressed second gas stream, or both; or ii) combining the compressed first gas stream and the second gas stream; treating the gas in a gas processing zone including a gas component removal unit, a gas desulfurization / acid gas removal unit, or both to produce a treated stream; d) adding CO 2 within at least a first portion of the treated stream 2 to produce a CO-enriched outlet stream. 2 forming CO in a CO conversion system; e) passing the CO2-enriched outlet stream through a bioreactor having a culture of one or more C1-fixing bacteria and fermenting to produce at least one fermentation product stream and a bioreactor tail gas stream; f) passing the tail gas stream through the first compressor, the gas processing zone, the CO 2 and recycling the CO to a CO conversion system, the first gas stream, the second gas stream, or the combination of the first gas stream and the second gas stream. [Invention 12] combined with the CO2-enriched outlet stream, a) the treated stream, or b) the first gas stream; or c) the second gas stream; or d) the combination of the first gas stream and the second gas stream; or e) the compressed first gas stream; or f) the compressed second gas stream; or g) combining the compressed first gas stream with a second gas stream; or h) The process according to invention 11, any combination thereof. [Invention 13] and converting at least a portion of the tail gas stream into CO of the tail gas stream selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit. 2 12. The process of claim 11, further comprising passing the second CO2-enriched eluate stream through a CO2 conversion system to CO to produce a CO2-enriched eluate stream; and recycling said second CO2-enriched eluate stream to said bioreactor. [Invention 14] the CO2-enriched outlet stream is a mixture of hydrogen and CO 2 and further comprising about 5:1:1, about 4.5:1:1, about 4.33:1:1, or about 3:1:1, about 2:1:1, about 1:1:1, or about 1:3:1 H 2 :CO:CO 2 12. The process of claim 11, comprising a molar ratio. [Invention 15] The CO 2 12. The process of claim 11, wherein the CO to CO conversion system comprises at least one of a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit. [Invention 16] 12. The process of claim 11, wherein the gas processing zone further comprises a deoxygenation unit, a catalytic hydrogenation unit, an adsorption unit, a thermal oxidizer, or any combination thereof. [Invention 17] 12. The process of claim 11, wherein the at least one fermentation product is selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol. [Invention 18] 12. A process according to claim 11, comprising: a) the first gas stream comprising hydrogen is produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof; or b) the CO 2 the second gas stream comprising a sugar-based ethanol source, a first generation corn ethanol source, a second generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugar beet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefin source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO 2 or is produced by a gas production source, including at least one of a natural gas processing production source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof; c) at least one of the C1-fixing bacteria is selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei, or The process according to invention 11, which is any combination thereof. [Invention 19] 12. The process of claim 11, wherein the CO2-enriched outlet stream comprises hydrogen, and the process further comprises separating hydrogen from the CO2-enriched outlet stream and recycling the separated hydrogen to combine with the tail gas stream or the compressor. [Invention 20] 20. The process of claim 19, further comprising compressing a remaining portion of the CO2-enriched outlet stream after separation of the hydrogen. [Invention 21] 12. The process of claim 11, wherein the tail gas stream comprises methane, and the process further comprises passing a portion of the tail gas stream through a methane conversion unit to produce a methane conversion unit effluent, and combining the methane conversion unit effluent with the tail gas stream. [Invention 22] 22. The process of claim 21, further comprising generating an oxygen-containing stream from an oxygen source and passing said oxygen-containing stream to said methane conversion unit. [Invention 23] passing a second gas stream comprising hydrogen from the hydrogen source through the bioreactor or combining it with the CO2-enriched outlet stream; 2 CO from sources 2 or combining with the CO2-enriched outlet stream, or any combination thereof. [Invention 24] combining a second gas stream comprising hydrogen from the hydrogen source with the CO2-enriched outlet stream, or 2 CO from the source 2 24. The process of claim 23, wherein combining a second gas stream comprising: [Invention 25] 24. The process of claim 23, wherein the ratio of the second gas stream comprising hydrogen from the hydrogen source to the CO2-enriched outlet stream entering the bioreactor is from about 0:1 to about 4:1. [Invention 26] The CO 2 12. The process of claim 11, wherein the CO to CO conversion system comprises a fired heater having a burner, and wherein the tail gas stream is recycled to at least the burner of the fired heater. [Invention 27] The CO 2 12. The process of claim 11, wherein the CO to CO conversion system includes a steam generator to generate steam, or a water knockout unit to generate a water stream, or both. [Invention 28] 12. The process of claim 11, further comprising passing a portion of the CO2-enriched outlet stream to an inoculator reactor, a buffer tank, or both. [Invention 29] 1. An integrated process for the production of at least one fermentation product from a gas stream, said process comprising: a) a first gas stream comprising hydrogen and CO 2 and a second gas stream comprising: b) operating at least a portion of said second gas stream, and optionally at least a portion of said first gas stream, under conditions to produce a CO2-enriched outlet stream; 2 and passing it through a CO conversion system. c) passing at least a portion of the hydrogen-containing first gas stream and the CO2-enriched outlet stream through a bioreactor having a culture of one or more C1-fixing bacteria and fermenting to produce at least one fermentation product stream and a bioreactor tail gas stream; d) compressing the bioreactor tail gas stream to produce a compressed bioreactor tail gas stream; e) combining, in any order, at least a first portion of said compressed bioreactor tail gas stream with: i) a gas desulfurization and / or acid gas removal unit; or ii) a gas component removal unit; or iii) passing the gas through both the gas desulfurization and / or acid gas removal unit and the gas component removal unit; producing a compressed treated bioreactor tail gas stream; f) recirculating the compressed treated bioreactor tail gas stream to i) combined with the first gas stream, the second gas stream, or a combination thereof; or ii) CO 2 to a CO conversion system, or iii) combined with the CO2-enriched outlet stream; or iv) any combination thereof, and g) optionally recycling a second portion of said compressed bioreactor tail gas stream to combine with said CO2-enriched outlet stream or said bioreactor. [Invention 30] At least another portion of the first gas stream containing hydrogen is added to the CO 2 30. The process of claim 29, further comprising passing the CO through a CO conversion system. [Invention 31] 30. The process of claim 29, further comprising compressing any portion of the first gas stream, the second gas stream, or a combination thereof. [Invention 32] 30. The process of claim 29, further comprising using a control valve to control the relative amounts of the first portion of the compressed tail gas stream and the second portion of the compressed tail gas stream. [Invention 33] and converting at least a portion of the tail gas stream into CO of the tail gas stream selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit. 2 30. The process of claim 29, further comprising passing the second CO2-enriched eluate stream through a CO2 conversion system to CO to produce a CO2-enriched eluate stream; and recycling said second CO2-enriched eluate stream to said bioreactor. [Invention 34] the CO2-enriched outlet stream is mixed with about 5:1:1, about 4.5:1:1, about 4.33:1:1, or about 3:1:1, about 2:1:1, about 1:1:1, or about 1:3:1 H 2 :CO:CO 2 30. The process of claim 29, including a molar ratio. [Invention 35] The CO 2 30. The process of claim 29, wherein the CO to CO conversion system comprises at least one of a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a reforming unit, or a plasma conversion unit. [Invention 36] 29. A process according to claim 29, comprising: a) the at least one fermentation product is selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol, or b) the first gas stream comprising hydrogen is produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof; or c) the CO 2 the second gas stream comprising a sugar-based ethanol source, a first generation corn ethanol source, a second generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugar beet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefin source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO 2 or is produced by a gas production source, including at least one of a natural gas processing production source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof; d) the at least one C1-fixing bacterium is selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei, or e) The process according to invention 29, any combination thereof.

Claims

1. 1. An integrated process for the production of at least one fermentation product from a gas stream, said process comprising: a) a first gas stream comprising hydrogen and CO ２ and a second gas stream comprising: b) passing at least a portion of the first gas stream and at least a portion of the second gas stream through a reverse water gas shift unit operating under conditions to produce a CO2-enriched outlet stream; c) passing the CO2-enriched outlet stream through a bioreactor having a culture of one or more C1-fixing bacteria and fermenting the bioreactor to produce at least one fermentation product stream and a bioreactor tail gas stream; d) compressing the bioreactor tail gas stream to produce a compressed bioreactor tail gas stream; e) recirculating the compressed bioreactor tail gas stream to i) combining with the first gas stream, the second gas stream, or a combination thereof; or ii) passing to the reverse water gas shift unit; or iii) combined with the CO2-enriched outlet stream; or iv) any combination thereof, and f) optionally recycling a second portion of said compressed bioreactor tail gas stream to combine with said CO2-enriched outlet stream or said bioreactor.

2. 10. The process of claim 1, further comprising combining at least a second portion of the first gas stream, at least a second portion of the second gas stream, or a combination thereof, with the CO2-enriched outlet stream.

3. 10. The process of claim 1, further comprising passing at least a second portion of the first gas stream, at least a second portion of the second gas stream, or a combination thereof, through the bioreactor.

4. 10. The process of claim 1, further comprising compressing any portion of the first gas stream, the second gas stream, or a combination thereof.

5. and converting at least a portion of the compressed bioreactor tail gas stream into CO 2 of the tail gas stream selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit. ２ 10. The process of claim 1, further comprising passing the CO2-enriched effluent through a CO2 conversion system to CO to produce a second CO2-enriched effluent stream and recycling the second CO2-enriched effluent stream to the bioreactor.

6. The CO2-enriched outlet stream is mixed with 5:1:1, 4.5:1:1, 4.33:1:1, or 3:1:1, 2:1:1, 1:1:1, or 1:3:1 H ２ :CO:CO ２ The process of claim 1 comprising a molar ratio.

7. 2. The process of claim 1, a) the at least one fermentation product is selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol; or b) the first gas stream comprising hydrogen is produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof; or c) the CO ２ the second gas stream comprising a sugar-based ethanol source, a first generation corn ethanol source, a second generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugar beet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefin source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO ２ or produced by a gas source, including at least one of a natural gas processing source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof; d) any combination thereof.

8. 2. The process of claim 1, wherein the at least one C1-fixing bacterium is selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei.

9. 1. An integrated process for the production of at least one fermentation product from a gas stream, said process comprising: a) a first gas stream comprising hydrogen and CO ２ and a second gas stream comprising: b) compressing at least a portion of the first gas stream, at least a portion of the second gas stream, or any combination thereof in a first compressor to produce a compressed first gas stream, a compressed second gas stream, and / or a combination of compressed first and second gas streams; c) i) at least a portion of the first gas stream or the compressed first gas stream, or both, and at least a portion of the second gas stream or the compressed second gas stream, or both; or ii) combining the compressed first gas stream and the second gas stream; processing the gas in a gas processing zone including a gas component removal unit, a gas desulfurization / acid gas removal unit, or both to produce a treated stream; d) removing CO 2 within at least a first portion of the treated stream; ２ to form CO in a reverse water gas shift unit operating under conditions to produce a CO2-enriched outlet stream; e) passing the CO2-enriched outlet stream through a bioreactor having a culture of one or more C1-fixing bacteria and fermenting to produce at least one fermentation product stream and a bioreactor tail gas stream; f) recycling said bioreactor tail gas stream to said first compressor.

10. the CO2-enriched outlet stream; a) the treated stream; b) the first gas stream; c) the second gas stream; d) said combining said first gas stream and said second gas stream; e) the compressed first gas stream; f) the compressed second gas stream, or g) combining the compressed first gas stream with a second gas stream; or h) any combination thereof 10. The process of claim 9, comprising combining

11. and converting at least a portion of the bioreactor tail gas stream into CO 2 of the tail gas stream selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit. ２ 10. The process of claim 9, further comprising passing the CO2-enriched effluent through a CO2 conversion system to CO to produce a second CO2-enriched effluent stream and recycling the second CO2-enriched effluent stream to the bioreactor.

12. the CO2-enriched outlet stream is a mixture of hydrogen and CO ２ and further comprising 5:1:1, 4.5:1:1, 4.33:1:1, or 3:1:1, 2:1:1, 1:1:1, or 1:3:1 H ２ :CO:CO ２ The process of claim 9, comprising a molar ratio.

13. 10. The process of claim 9, wherein the gas processing zone further comprises a deoxygenation unit, a catalytic hydrogenation unit, an adsorption unit, a thermal oxidizer, or any combination thereof.

14. 10. The process of claim 9, wherein the at least one fermentation product is selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol.

15. 10. The process of claim 9, a) the first gas stream comprising hydrogen is produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof; or b) the CO ２ the second gas stream comprising a sugar-based ethanol source, a first generation corn ethanol source, a second generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugar beet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefin source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO ２ or produced by a gas source, including at least one of a natural gas processing source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof; c) at least one of the C1-fixing bacteria is selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei, or The process of claim 9, any combination thereof.

16. 10. The process of claim 9, wherein the CO2-enriched outlet stream comprises hydrogen, and the process further comprises separating hydrogen from the CO2-enriched outlet stream and recycling the separated hydrogen to combine with the bioreactor tail gas stream or the compressor.

17. 17. The process of claim 16, further comprising compressing a remaining portion of the CO2-enriched outlet stream after separation of the hydrogen.

18. 10. The process of claim 9, wherein the bioreactor tail gas stream comprises methane, and the process further comprises passing a portion of the bioreactor tail gas stream through a methane conversion unit to produce a methane conversion unit effluent, and combining the methane conversion unit effluent with the bioreactor tail gas stream.

19. 20. The process of claim 18, further comprising generating an oxygen-containing stream from an oxygen source and passing said oxygen-containing stream through said methane conversion unit.

20. passing a second gas stream comprising hydrogen from a hydrogen source through the bioreactor or combining it with the CO2-enriched outlet stream; ２ CO from sources ２ or combining with the CO2-enriched outlet stream, or any combination thereof.

21. combining a second gas stream comprising hydrogen from the hydrogen source with the CO2-enriched outlet stream, or ２ The CO from the source ２ 21. The process of claim 20, wherein combining a second gas stream comprising:

22. 21. The process of claim 20, wherein the ratio of the second gas stream comprising hydrogen from the hydrogen source to the CO2-enriched outlet stream entering the bioreactor is from 0:1 to 4:

1.

23. 10. The process of claim 9, wherein the reverse water gas shift unit comprises a fired heater having a burner, and wherein the bioreactor tail gas stream is recycled to at least the burner of the fired heater.

24. 10. The process of claim 9, wherein the reverse water gas shift unit comprises a steam generator that generates steam, or a water knockout unit that generates a water stream, or both.

25. 1. An integrated process for the production of at least one fermentation product from a gas stream, said process comprising: a) a first gas stream comprising hydrogen and CO ２ and a second gas stream comprising: b) passing at least a portion of the second gas stream, and optionally at least a portion of the first gas stream, through a reverse water gas shift unit operating under conditions to produce a CO2-enriched outlet stream; c) passing at least a portion of the hydrogen-containing first gas stream and the CO2-enriched outlet stream through a bioreactor having a culture of one or more C1-fixing bacteria and fermenting to produce at least one fermentation product stream and a bioreactor tail gas stream; d) compressing the bioreactor tail gas stream to produce a compressed bioreactor tail gas stream; e) recirculating the compressed bioreactor tail gas stream to i) combined with the first gas stream, the second gas stream, or a combination thereof; or ii) Passing to a reverse water gas shift unit; or iii) combined with the CO2-enriched outlet stream; or iv) any combination thereof, and f) optionally recycling a second portion of said compressed bioreactor tail gas stream to combine with said CO2-enriched outlet stream or said bioreactor.

26. 26. The process of claim 25, further comprising passing at least another portion of the first gas stream comprising hydrogen through the reverse water gas shift unit.

27. 26. The process of claim 25, further comprising compressing any portion of the first gas stream, the second gas stream, or a combination thereof.

28. and converting at least a portion of the compressed bioreactor tail gas stream into CO 2 of the tail gas stream selected from a reverse water gas shift unit, a thermal catalytic conversion unit, a partial combustion unit, a plasma conversion unit, a gasification unit, or a reforming unit. ２ 26. The process of claim 25, further comprising passing the CO2-enriched effluent through a CO2 conversion system to CO to produce a second CO2-enriched effluent stream and recycling the second CO2-enriched effluent stream to the bioreactor.

29. The CO2-enriched outlet stream is mixed with 5:1:1, 4.5:1:1, 4.33:1:1, or 3:1:1, 2:1:1, 1:1:1, or 1:3:1 H ２ :CO:CO ２ 26. The process of claim 25, comprising a molar ratio.

30. 26. The process of claim 25, a) the at least one fermentation product is selected from ethanol, acetate, butanol, butyrate, 2,3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate, isoprene, fatty acids, 2-butanol, 1,2-propanediol, hexanol, octanol, or 1-propanol; or b) the first gas stream comprising hydrogen is produced by a hydrogen production source comprising at least one of a water electrolyzer, a hydrocarbon reforming source, a hydrogen purification source, a solid biomass gasification source, a solid waste gasification source, a coal gasification source, a hydrocarbon gasification source, a methane pyrolysis source, a refinery tail gas production source, a plasma reforming reactor, a partial oxidation reactor, or any combination thereof; or c) the CO ２ the second gas stream comprising a sugar-based ethanol source, a first generation corn ethanol source, a second generation corn ethanol source, a sugarcane ethanol source, a sucrose ethanol source, a sugar beet ethanol source, a molasses ethanol source, a wheat ethanol source, a grain-based ethanol source, a starch-based ethanol source, a cellulosic ethanol source, a cement source, a methanol synthesis source, an olefin source, a steel source, a ferroalloy source, a refinery tail gas source, a secondary combustion gas source, a biogas source, a landfill source, an ethylene oxide source, a methanol source, an ammonia source, a mined CO ２ or produced by a gas source, including at least one of a natural gas processing source, a gasification source, an organic waste gasification source, direct air capture, or any combination thereof; d) the at least one C1-fixing bacterium is selected from Clostridium autoethanogenum, Clostridium ljungdahlii, or Clostridium ragsdalei, or e) any combination thereof.

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