Process for capturing carbon dioxide from air and directly converting carbon dioxide into fuel and chemicals

Abstract

To provide a process for converting renewable electricity, air, and water into fuel and chemicals with low or zero carbon emissions.SOLUTION: An integrated process for converting a feed stream comprising air, electricity, and water into a product stream comprising hydrocarbons comprises: a) an electrolysis step of converting a feed stream of an electrolytic cell containing water into a product stream of an electrolytic cell containing hydrogen and oxygen; b) a direct air capture step of removing carbon dioxide from an air stream; c) a reverse water gas shift step for generating a reverse water gas shift product stream; d) a hydrocarbon synthesis step for generating a hydrocarbon synthesis product stream; and e) an autothermal reforming step.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method, catalyst, and material for converting renewable electricity, air, and water into low-carbon or zero-carbon fuels and chemicals by directly recovering carbon dioxide from the atmosphere and converting the carbon dioxide into fuels and chemicals using hydrogen generated by the electrolysis of water.

Background Art

[0002] Carbon dioxide is produced by many industrial and biological processes. Carbon dioxide is typically emitted into the atmosphere, and the concentration of carbon dioxide in the Earth's atmosphere has been continuously increasing since the start of the Industrial Revolution. Carbon dioxide is recognized as a significant greenhouse gas that causes global climate change. In particular, it is difficult to reduce carbon dioxide emissions at the source of generation, and generally, it has not been successful. The amount of carbon dioxide in the atmosphere continues to increase. A more preferable process for dealing with carbon dioxide is to efficiently recover carbon dioxide from the air in the atmosphere and convert it into useful products, such as fuels (diesel fuel, kerosene, jet fuel, gasoline or gasoline blend fuel, or other fuels) and chemicals (methanol, ammonia, solvents, waxes, olefins, or other chemicals), which can replace fuels and chemicals produced from fossil resources such as petroleum and natural gas, and as a result, reduce the net total emissions of carbon dioxide into the atmosphere. This is what low-carbon, ultra-low-carbon, or zero-carbon fuels and chemicals mean.

[0003] Carbon dioxide can be obtained from several sources. In manufacturing plants related to the industry of producing ammonia for fertilizers from natural gas or coal, a large amount of carbon dioxide is generated. In ethanol plants that convert corn or wheat into ethanol, a large amount of carbon dioxide is generated. In power plants that generate electricity from natural gas or coal, a large amount of carbon dioxide is generated. Since natural gas deposits can also contain a large amount of carbon dioxide, in some locations, natural gas treatment plants need to process a fairly large amount of carbon dioxide. To recover and utilize CO2, it is often necessary to separate carbon dioxide from an exhaust gas stream or another stream that does not have carbon dioxide as the main component. Alkylamines are used to remove carbon dioxide from the flue gas steam. The alkylamines used in this process include monoethanolamine, diethanolamine, methyldiethanolamine, diisopropylamine, aminoethoxyethanol, or combinations thereof. Metal Organic Framework (MOF) materials have also been used as a means to separate carbon dioxide from a low-concentration stream using chemisorption or physisorption and recover carbon dioxide from this stream. Other processes to obtain high-concentration carbon dioxide include chemical-looping combustion, which allows the carbon dioxide generated during the combustion process to be recovered by a circulating metal oxide material.

[0004] Carbon dioxide can also be recovered from the atmosphere, which is called direct air capture (DAC) of carbon dioxide. Since the concentration of carbon dioxide in the air is quite low, about 415 ppm, the challenges of recovering carbon dioxide from air are different from those of recovering it from exhaust gas or other sources. At such low concentrations, liquid alkylamines often do not function well because amine losses become too large. MOF compounds, based on the physical absorption of carbon dioxide, usually have too little carbon dioxide uptake. The historical development of the direct air capture of CO2 is detailed in the publication, Sanz-Perez, et al, "Direct Capture of CO2 from Ambient Air", Chem. Rev. 2016, 116, 11840-11876. Numerous materials have been tried to recover carbon dioxide from low-concentration air streams.

[0005] Over the past decade, two major types of materials and processes have emerged as the most promising. The first promising set of materials and processes involves the use of solid adsorbents with tethered amines. This utilizes the CO₂ capture ability of amines (similar to the liquid amines described earlier), but these types of materials are chemically tethered to a solid. Unlike the metal oxide-based chemisorbents described earlier, the supported amine adsorbents operate under nearly ambient conditions and can ideally be regenerated with gentle temperature changes. Choi et al, "Application of Amine-Tethered Solid Sorbents for Direct CO₂ Capture from Ambient Air", Environmental Science & Technology, 2011, 45, 2420-2427 provides a detailed description of these materials. However, these chemisorbents require a temperature change to release the carbon dioxide and an inert gas to flush it out. In the laboratory, nitrogen or argon or other inert gases are used. Commercially, however, the separation of the inert gas from the carbon dioxide becomes almost as important an issue as the initial capture of the carbon dioxide. To overcome this inert gas problem, it has been shown that for some of these supported adsorbents, water vapor can be used to release the carbon dioxide and regenerate the adsorbent. See Wen Li, et.Al "Steam Stripping for Regeneration of Supported Amine-Based CO₂ Adsorbents", ChemSusChem 2010, 3, 899-903. As described in US9,555,365, the technology developed by Global Thermostat falls into this general category of approaches for DAC.

[0006] The second material and process uses an aqueous metal hydroxide to react with CO2 in the air to produce a metal carbonate, which is calcined to release the recovered CO2 and remake the metal hydroxide. This cycle can be carried out in a continuous series of chemical reactors. This technology has been advanced by Carbon Engineering. Their process is described in detail in Keithet al, "A Process for the Capture of CO2from theAtmosphere", Joule 2, 1573-1594, August 15, 2018. The carbon dioxide resulting from their process is cooled from 900 °C and compressed to a pressure higher than 100 atmospheres, either for geological isolation or to be sent to a CO2 pipeline. A renewable hydrogen (H2) source can be produced by electrolysis of water using electricity.

[0007] [Chemical formula]

[0008] This reaction uses electricity to decompose water into hydrogen and oxygen. An electrolytic cell consists of an anode and a cathode separated by an electrolyte. The function of the electrolytic cell varies widely depending on slightly different methods, which is mainly due to the difference in the type of electrolyte material required.

[0009] However, each electrolysis technology has a theoretical minimum electrical energy input of 39.4 kWh / kgH2 (HHV of hydrogen) when water is supplied to the system at normal pressure and room temperature and all energy input is provided in the form of electricity. If appropriate thermal energy is supplied to the system, the required electrical energy input may be less than 39.4 kWh / kgH2. For example, in high-temperature electrolysis such as PEM steam electrolysis and especially solid oxide electrolysis, if the electrolyzer is co-located with a low-cost heat source or waste heat source, the operating cost can be reduced compared to the case where all energy is supplied electrically. (Study on development of water electrolysis in the EU Final Report, E4tech Sari with Element Energy Ltd for the Fuel Cells and Hydrogen Joint Undertaking, February 2014). Considering the high energy required for electrolysis, the zero-carbon fuel and chemical plant envisioned by the present invention need to be located at or near locations with inexpensive renewable electricity.

[0010] In addition to electrolysis, current important research is examining methods of decomposing water into hydrogen and oxygen using light energy and photocatalysts. (Acar et al, Int. J. Energy Res. 2016; 40: 1449-1473).

[0011] Recent developments in liquid organic hydrogen carriers (LOHCs) have shown that it is possible to react hydrogen with toluene at the site of electrolysis or water splitting to produce methylcyclohexane, transport it as a liquid to another location, dehydrogenate the hydrogen, and return the liquid toluene to the original location to continue the cycle. See Niermann et al, “Liquid Organic Hydrogen Carries (LOHC’s) - Techno-Economic Analysis of LOHC’s in a Defined Process Scheme”, Energy Environ. Sci. 2019, 12, 290. This development means that it is possible to separate the location of electrolysis from the ultimate users of renewable hydrogen.

[0012] One of the reactions that has been considered for the utilization of carbon dioxide is the reverse water gas shift (RWGS) reaction.

[0013]

Chem.

[0014] This reaction is the conversion of carbon dioxide and hydrogen into carbon monoxide and water. This reaction is endothermic at room temperature, requires heat for progression, and requires elevated temperature and a good catalyst to significantly convert carbon dioxide.

[0015] Several catalysts have been disclosed for the RWGS reaction. The major catalysts previously studied were Cu or Pt or Rh dispersed on a support of metal oxide. (Daza & Kuhn, RSC Adv. 2016, 6, 49675-49691).

[0016] If there is CO (carbon monoxide) from the RWGS reaction and hydrogen from the electrolysis of water, useful products may be obtained via a hydrogenation catalyst from carbon monoxide to hydrocarbons. A mixture of H2 and CO is called synthesis gas or syngas. Syngas can be used as a feedstock for producing chemical products, including liquid fuels, alcohols, acetic acid, dimethyl ether, and many other chemical products. If H2 from water and CO from CO2 can be produced, as a result, it is possible to have truly net-zero carbon fuels and chemicals without the emission of CO2 or greenhouse gases that occur in the production of syngas and in the conversion of syngas to fuels and chemicals.

[0017] Catalytically hydrogenating CO to produce light gases, liquids, and waxes from methane to heavy hydrocarbons (C 100 and above), in addition to oxygenated hydrocarbons, is generally called Fischer-Tropsch (or F-T) synthesis. In conventional low-temperature (<250 °C) F-T processes, mainly high-weight (or high weight %) F-T waxes (C 25 and above) are produced from the catalytic conversion process. These F-T waxes are then hydrocracked and / or further processed to produce diesel, naphtha, and other fractions. Light hydrocarbons are also produced during this hydrocracking process and may require further upgrading to produce practical products. Catalysts commonly used in F-T are either cobalt (Co)-based catalysts or iron (Fe)-based catalysts, which are also active in the water gas shift (WGS) reaction that results in the conversion of the supplied carbon monoxide to carbon dioxide. See S.S. Ail, S. Dasappa / Renewable and Sustainable Energy Reviews 58(2016) 267-286 for more details on state-of-the-art Fischer-Tropsch. Summary of the Invention

Problems to be Solved by the Invention

[0018] Despite a large amount of prior research on this subject and the global importance of success in these technological developments, excellent methods, systems, and catalysts for recovering carbon dioxide from the atmosphere and converting it into useful fuels and chemicals have not been developed to date. There is a need for better methods, systems, and catalysts.

Means for Solving the Problems

[0019] The present invention relates to a method, catalyst, and material for converting renewable electricity, air, and water into low-carbon or zero-carbon fuels and chemicals by directly recovering carbon dioxide from the atmosphere and using hydrogen generated by the electrolysis of water to convert the carbon dioxide into fuels and chemicals. In this method, water is converted into hydrogen in an efficient electrolysis unit using renewable electricity as an energy source, and the hydrogen is directly transported to a direct air capture (DAC) site via an LOHC system if necessary. The hydrogen is used in a beneficial way to improve the efficiency of the DAC system. Carbon dioxide and hydrogen are reacted in a reverse water-gas shift (RWGS) reactor to form carbon monoxide and water, where the reaction heat is supplied by renewable electricity. The catalyst used in the RWGS reactor is a new solid solution catalyst. The generated carbon monoxide and additional hydrogen are reacted in a liquid fuel production reactor using a new catalyst that directly produces fuels and chemicals to form fuels and chemicals. The net product produced is a hydrocarbon having a length of 4 to 24 carbon atoms. Other products including methanol, wax, ammonia, solvents, and other fuels and chemicals may be produced from the syngas.

Brief Description of the Drawings

[0020]

Figure 1

[0021]

Figure 2

[0022]

Figure 3

[0023]

Figure 4

[0024] Figures 5 and 6 show an integrated and highly efficient process for converting carbon dioxide, water, and renewable electricity into renewable fuels and chemicals.

[0025]

Figure 5

[0026]

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention includes several subsystems. FIG. 1 shows the overall process of producing fuels and chemicals from air, water, and renewable electricity. The overall process starts with (1) generating renewable hydrogen by electrolysis from renewable or low-carbon electricity and water, (2) storing the renewable hydrogen if necessary and transporting it to a second location via a liquid organic hydrogen carrier (LOHC) system, (3) direct air capture (DAC) for recovering carbon dioxide from the atmosphere, using the hydrogen from the electrolysis step to improve the efficiency of the DAC process, (4) generating CO from CO2 in the RWGS system, (5) converting syngas to hydrocarbons in a liquid fuel production (LFP) reactor system, and (6) in the autothermal reformer (ATR) section, converting the light hydrocarbons (C1 - C5) generated in the liquid fuel production (LFP) reactor into hydrogen and carbon monoxide (syngas) and recycling them back to the LFP reactor.

[0028] Another aspect of the present invention is to burn a calciner using tail gas in the process of direct air capture. The calciner is ideally to burn oxygen using oxygen from the electrolyzer, concentrate the CO2 from the calciner, and make it recyclable back to the RWGS process.

[0029] As shown in FIG. 1, the electrolysis system generates renewable hydrogen. Water is supplied to the electrolysis system. Renewable electricity is used to supply power to the electrolysis system. Hydrogen can be generated by electrolysis of water.

[0030]

Chemical formula

[0031] An electrolyzer is composed of an anode and a cathode separated by an electrolyte. If the method is slightly different, the functions of the electrolyzer will vary significantly. In various electrolyzer designs, various electrolysis technologies can be used, including alkaline electrolysis, membrane electrolysis, and high-temperature electrolysis. Alkaline electrolysis is preferred because large-scale operation exceeding 1 MW is commercially viable. Various electrolytes containing liquids of KOH and NaOH can be used, with or without using an activating compound. To improve the stability of the electrolyte, an activating compound can be added to the electrolyte solution. Many of the ionic activators for the hydrogen generation reaction are composed of an ethylenediamine-based metal chloride complex and Na2Mo4 or Na2WO4. Various electrolysis catalysts can be used on electrodes containing many different combinations of metals and oxides such as Raney-nickel-aluminum, and can be strengthened by adding cobalt or molybdenum to the alloy.

[0032] For example, combinations of several transition metals such as Pt2Mo, Hf2Fe, and TiPt are used as cathode materials and exhibit significantly higher electrode catalyst activity than state-of-the-art electrodes.

[0033] Some electrolyzers are designed to operate at high pressures, such as 30 to 50 bar, and produce hydrogen and oxygen. Pressurized electrolyzers are preferred because they can eliminate the energy-intensive step of syngas compression. Water at the cathode combines with electrons from the external circuit to form hydrogen gas and negatively charged oxygen ions. The oxygen ions pass through the solid ceramic membrane and react at the anode to form oxygen gas and generate electrons for the external circuit. In this way, both hydrogen gas and oxygen gas are produced within the electrolyzer. In one embodiment, multiple electrolyzers operate in parallel. There is no electrolyzer that operates with 100% energy efficiency, and energy consumption is extremely important for the economic operation of the facility. The energy consumption in the electrolyzer is desirably less than 200 megawatt-hours (MWh) per metric ton (MT) of hydrogen produced, preferably less than 120 MWh / MT of hydrogen produced, and more preferably less than 60 MWh / MT of hydrogen produced. In the case of an alkaline electrolyzer embodiment, the power consumption is greater than 39.4 MWh / MT of hydrogen produced. However, in the case of a high-temperature electrolyzer embodiment, when waste heat is used to heat the electrolyzer above room temperature, the power consumption may be reduced to less than 39.4 MWh / MT of hydrogen produced.

[0034] In the present invention, several different direct air capture (DAC) technologies can be used. The first embodiment of the DAC technology is based on a solid amine-based adsorbent. FIG. 2 shows an embodiment of the present invention. A supported amine adsorbent based on a primary, secondary, or tertiary amine is installed in the DAC reactor. The amine adsorbent can chemically adsorb carbon dioxide in the air passing through the DAC reactor. As a result, a stream of air with a greatly reduced amount of carbon dioxide exits the DAC reactor. This occurs at approximately room temperature and atmospheric pressure. A blower can be used to draw air through the reactor. The pressure drop through the DAC reactor is optimized by the installation of the solid amine adsorbent in the DAC reactor and the size management of the amine adsorbent.

[0035] There are at least three classes of solid-supported amine sorbents that can be used. Class 1 sorbents are composed of a polymeric or oxide support (typically silica) physically loaded with an amine containing a small molecule or small polymer. Class 2 sorbents are based on amine species covalently bonded to the surface of a solid support, such as by using an organosilane. For example, a Class 1 sorbent may be tetraethylenepentamine or diethanolamine impregnated in MCM-41 silica. A typical Class 2 sorbent is MCM-41 with grafted triamine and enlarged pores, which shows good adsorption properties at low partial pressures of carbon dioxide. Class 3 sorbents are amine-based solid sorbents described as hyperbranched aminosilica (HAS) materials synthesized by in situ ring-opening polymerization of aziridine, detached from a porous support. These sorbents typically have an amine loading of 2 - 10 mmol / g, a pore diameter of 4 - 7 nm, a BET surface area of 40 - 600 m 2 / g, and a pore volume of 0.1 - 0.8 cc / g. These materials function well with humid or dry air under atmospheric conditions and show carbon dioxide adsorption of 0.5 - 4.0 mmol / g at a carbon dioxide concentration of about 400 ppm. Ideally, the DAC reactor is operated so that about 20 - 50% of the carbon dioxide in the air passing through the DAC reactor is removed. Removing more than 50% of the carbon dioxide generally is not preferred as it significantly reduces the ability of the sorbent to recover carbon dioxide. After the CO2 uptake cycle is complete, the DAC reactor is switched to the regeneration cycle of the sorbent to release CO2. In this cycle, the hydrogen generated in the electrolyzer is heated to about 90 - 120 °C by indirect heat exchange. As this hydrogen passes through the DAC reactor, the adsorbed carbon dioxide is released and mixed with the carbon dioxide gas. Usually, the amount of hydrogen gas used results in a molar ratio of hydrogen to carbon dioxide of 2.0 and 3.0 mol / mol in the gas exiting the DAC reactor. This stream becomes the feed stream for RWGS in Figure 5. This integration particularly improves the efficiency of the DAC system as water vapor is not required and separation is not required.

[0036] The second embodiment of the DAC technology is based on various process chemistries. Figure 3 shows that embodiment. This process involves recovering carbon dioxide from the air through the conversion of metal hydroxide to metal carbonate. Using a blower, air passes through an air contactor. The air contactor brings the air carrying carbon dioxide into contact with aqueous KOH. KOH reacts with carbon dioxide to produce aqueous K2CO3. This aqueous K2CO3 is reacted with solid Ca(OH)2 in a pellet reactor. K2CO3 is converted back to KOH, and Ca(OH)2 is converted to solid CaCO3. Calcium carbonate is supplied to a calcination furnace system to convert calcium carbonate to CaO. The calcination furnace system is newly a circulating fluid bed and operates at 50 psig or higher. This is an oxygen blown circulating fluid bed system where oxygen is blown in. Oxygen is used as the fluidizing gas at a superficial velocity between 0.25 and 2.5 m / s. Through a lance, natural gas or other combustible-containing gas is supplied to the solid bed, where it reacts with oxygen to raise the temperature to 900 °C. As a result, the reaction of CaCO3 to CaO + CO2 occurs with a conversion efficiency of 90% or more. The solid CaO is separated from the gaseous CO2 in a cyclone system. The solid CaO is supplied to a slaker reactor, where it is converted to Ca(OH)2 for use in the pellet reactor. The hot CO2-containing gas is immediately mixed with the hydrogen produced in the electrolyzer. Usually, the amount of hydrogen gas mixed with carbon dioxide is such that the molar ratio of hydrogen to carbon dioxide in the gas exiting the DAC reactor system is 2.0 and 3.0 mol / mol. This stream becomes the feed stream for RWGS in Figure 5. This integration eliminates the need for cooling or compression of carbon dioxide, thus significantly improving the efficiency of the DAC system. Since the mixed gas is already at 300 °C or higher, the need for heating in this embodiment is also significantly reduced for the RWGS feed.

[0037] Figure 4 shows the LOHC system in one embodiment of the present invention. It is possible for the electrolyzer and the DAC system to be in the same physical location. However, the DAC unit is likely to be at the source of the generated fuel and chemicals, while the electrolyzer may be in an area with abundant sunlight, wind or other renewable or low-carbon resources that can be used to generate the renewable electricity for hydrogen production. In this case, it is necessary to transport the hydrogen generated by the electrolyzer to a second location. Figure 4 shows how to achieve this using the LOHC system. There are several possible LOHC materials, but the most promising one seems to be methylcyclohexane (MHC) which can be produced by reacting toluene with hydrogen. This takes place in the hydrogenator in Figure 4. MHC is a liquid and can be easily transported to location 2, which is separate from the location of the electrolyzer. MHC can then be dehydrogenated at location 2 to produce hydrogen gas and toluene. The toluene is then returned to location 1 to complete the cycle. The dehydrogenation is carried out in a catalytic reaction system. A number of catalysts can be used, but it can include S-Pt on alumina. The temperature of the dehydrogenation reaction is between 340 and 360 °C and is accompanied by a pressure between 1 and 30 bar. The MCH conversion is higher than 95% and the hydrogen yield is higher than 95%. The high temperature of the dehydrogenation reactor can be beneficially utilized in the DAC process of metal hydroxides. The hydrogen generated in the dehydrogenation reactor is mixed with the CO2 generated by the calciner, resulting in a gas stream with a temperature exceeding 400 - 500 °C, which can be used as an immediate (with some additional preheating) feed to the RWGS reaction system shown in Figure 5.

[0038] Figure 5 shows a RWGS system for generating CO from CO₂. Zero-carbon or ultra-low-carbon fuels and chemicals require that fossil fuels not be burned in the process of producing the fuels and chemicals. This means that heating the feed to the integrated process needs to be by indirect means (a cross exchanger) or via electric heating where electricity comes from zero-carbon or renewable resources such as wind, solar, geothermal, or nuclear power.

[0039] In Figure 5, hydrogen and carbon dioxide are in streams 1 and 2, forming a mixed gas (stream 3). The H₂ / CO₂ ratio is between 2.0 and 5.0 mol / mol, more preferably between 3.0 and 4.0 mol / mol. The mixed RWGS feed can be heated to a temperature higher than 900°F within unit 4 by indirect heat exchange. (482℃) It is important to provide heat for this initial temperature rise without using direct combustion of carbon-containing gases, as using direct combustion of carbon-containing gases means that CO₂ is being produced, which may negate the effect of converting CO₂ into useful fuels and chemicals.

[0040] The feed gas for RWGS containing the combined H₂ and CO₂ is heated to an inlet temperature (stream 5) higher than 1,400°F or preferably higher than 1,500°F, at least partially, in a preheater outside the main reaction vessel to produce a heated feed gas. (760℃) Figure 5 shows heating electrically to a temperature higher than 1,400°F, preferably higher than 1,500°F, more preferably higher than 1,600°F, the temperature of the feed gas by indirect heat exchange. (816℃)

[0041] (760℃) (816℃) (871℃) ​​​​It shows a preheater as unit 4 that raises the temperature to a higher level. There are numerous methods for electrically heating the supply gas. One method is by means of electric heating within an electrically heated radiant furnace. In this embodiment, at least a portion of the supply gas passes through heating coils within the furnace. The heating coils within the furnace are surrounded by radiant electric heating elements. The radiant electric heating elements can be made from a number of materials. The heating elements may be made of nickel-chromium alloy. These elements may be wound in strip or wire form, or may be cast in a zigzag shape. The elements are supported by an insulated steel shell, and generally ceramic fibers are used for insulation. The radiant elements may be divided into a plurality of zones to control the heating pattern. A plurality of coils and a plurality of compartments may be required to supply heat to the supply gas and produce the heated supply gas. In a radiant furnace, an appropriate design for the heating elements and fluid coils is necessary to ensure good view factors and good heat transfer. In another embodiment of the present invention, the gas passes directly over the heating elements, whereby the gas is heated by convective heat transfer. It is desirable that the power consumption by the radiant furnace be as low as possible. The power consumption by the radiant furnace is less than 0.5 MWh (megawatt-hour) / metric ton (MT) of CO2 in the supply gas, more preferably less than 0.40 MWh / CO2 MT, and even more preferably less than 0.20 MWh / CO2 MT.

[0042] The heated feed gas for the RWGS is then fed into the RWGS main reaction vessel (Unit 6). There are two possible embodiments for the RWGS main reaction vessel. In the first embodiment, the RWGS main reaction vessel is adiabatic or nearly adiabatic and is designed to minimize heat loss, but no heat is added to the main reaction vessel and the temperature inside the main reaction vessel decreases from the inlet to the outlet of the reactor. In the second embodiment, the RWGS main reaction vessel is similarly designed, but additional heat is added to the vessel to maintain an isothermal or nearly isothermal temperature profile inside the vessel. Heat may be added to the vessel by an internal or external heater or by other means.

[0043] The RWGS main reaction vessel (Unit 6) is a reactor having a length greater than its diameter. The inlet of the main reaction vessel is smaller than the overall diameter of the vessel. The main reaction vessel is a steel vessel. The steel vessel is insulated internally to limit heat loss. Various insulation materials may be used, including a poured or castable refractory lining or insulating bricks to limit heat loss to the environment (see Harbison-Walker Handbook of Refractory Practices, 2005, https: / / mha-net.org / docs / Harbison%20Walker%202005%20Handbook.pdf).

[0044] The catalyst bed is inside the main reaction vessel. The catalyst can be in the form of granules, pellets, spheres, trilobes, quadra-lobes, monoliths or any other arbitrarily designed shape in order to minimize the pressure drop across the reactor. Ideally, the shape and particle size of the catalyst are controlled such that the pressure drop across the reactor is less than 50 pounds per square inch (psi) [345 kPa] per square inch, more preferably less than 20 psi [138 kPa]. The size of the catalyst form can have a characteristic dimension between 1 mm and 10 mm. The catalyst particles have an internal surface area wider than 40 m 2 / g, more preferably wider than 80 m 2 / g, and preferably have a surface area of 100 m 2 / g and are a structural material that is a porous material. Some catalyst materials are expected to be able to catalyze the RWGS reaction. Previously studied RWGS catalysts were Cu or Pt or Rh dispersed on a metal oxide support. (Daza & Kuhn, RSC Adv. 2016, 6, 49675-49691). We have found that the preferred catalyst is a solid solution catalyst having a transition metal on a metal oxide support.

[0045] The RWGS catalyst used in this method is a highly versatile and high-performance solid solution-based catalyst and can efficiently carry out the RWGS reaction. This robust solid solution catalyst has high thermal stability up to 1,100 °C, does not form carbon (coke), and has good resistance to contaminant substances that may be present in the recovered CO2 stream.

[0046] This catalyst exhibits high activity at a low metal concentration (0.5 - 20 wt%) compared to other catalysts that require loading of at least 30 wt% of transition metals and other metals. Moreover, there is no need to use expensive noble metals to improve the performance of the catalyst. The manufacturing process for the RWGS catalyst is also important in that it produces a catalyst that forms a unique solid solution phase and a bimetallic crystal phase without segregating the metal phase. This unique chemical structure improves the resistance to coking compared to conventionally metal-supported catalysts. For example, the resistance to poisons such as sulfur and ammonia is also improved. Furthermore, this catalyst exhibits improved catalytic activity with a narrow surface area compared to a segregated catalyst phase of single metal atoms. This catalyst does not require alkali promotion necessary for suppressing carbon deposition. In the RWGS main reaction vessel, the conversion per pass from CO2 to CO is typically 60 - 90%, more preferably 70 - 90%. When an adiabatic reactor embodiment is used, the temperature in the RWGS main reaction vessel decreases from the inlet to the outlet. The outlet temperature of the RWGS main reaction vessel is 100 °F(56℃) ~200°F (111℃) lower, more preferably 105 °F(58℃) ~160°F (89℃) lower than that at the inlet of the main reactor. The weight hourly space velocity (WHSV) for RWGS, which is the mass flow rate of the RWGS reactants (H2 + CO2) per hour divided by the mass of the catalyst in the bed of the RWGS main reactor, is between 1,000 hr -1 ~60,000 hr -1 and more preferably between 5,000 hr -1 ~30,000 hr -1 .

[0047] The gas exiting the RWGS main reaction vessel is the product gas of RWGS (stream 7). The product gas of RWGS contains carbon monoxide (CO), hydrogen (H2), unreacted carbon dioxide (CO2), and water (H2O). Furthermore, the product gas of RWGS may contain a small amount of methane (CH4) produced in the main reaction vessel by side reactions.

[0048] At this point in the present method, the product gas of the RWGS can be used in various ways. The product gas can be cooled, compressed, and used in downstream processes to produce fuel and chemicals. The product gas of the RWGS can also be cooled, (compressed within unit 8), sent back to the preheater, and returned to and supplied to the main reaction vessel.

[0049] As shown in units 9 and 10, the product gas of the RWGS can also be reheated in the second electrical preheater, sent to the second reaction vessel, and additional conversion of CO2 to CO can be carried out. Unit 11 shows the optional compression before sending the syngas to the synthesis step of liquid fuel production.

[0050] Figure 6 shows a liquid fuel production (LFP) reactor system. This is also known as the hydrocarbon synthesis step. The LFP reactor converts CO and H2 into long-chain hydrocarbons that can be used as liquid fuels and chemicals. The syngas (stream 12) is mixed with the recycled syngas to produce a feed stream 13 to the LFP reactor and, optionally, a product (stream 21) from the ATR (unit 19) described later. The gas mixture supplied to the LFP reactor is shown as stream 14. The feed to the LFP reactor contains H2 and CO. Ideally, in this stream, the ratio of H2 to CO is between 1.9 and 2.2 mol / mol.

[0051] The LFP reactor (unit 15) is a multi-tubular fixed bed reactor system having a plurality of tubes. Each tube of the LFP reactor can have a diameter between 13 mm and 26 mm. The length of the tubes of the reactor is generally longer than 6 m, and more preferably longer than 10 m. The LFP reactor is generally oriented vertically such that the feed to the LFP reactor enters the upper part of the LFP reactor. However, depending on the situation, the reactor can be oriented horizontally, and in situations where there are height limitations, it may also be advantageous to install the reactor at an angle.

[0052] Most of the length of the tubes of the LFP reactor is filled with the LFP catalyst. To assist in distributing the feed to the LFP reactor within the tubes of the LFP reactor, the LFP catalyst may also be mixed with a diluent such as silica or alumina, for example. Due to the chemical reactions occurring within the LFP reactor, a product gas of LFP containing hydrocarbons (C4-C24 in length) and water is produced. It is important that the LFP reactor does not generate a large amount of CO2. It is desirable that less than 2% of the CO in the feed to the LFP reactor is converted to CO2 within the LFP reactor. It is also important that only a limited amount of carbon monoxide in the feed to the LFP reactor is converted to hydrocarbons having a carbon number greater than 24. Preferably, less than 10% by weight of the hydrocarbon fraction of the LFP product has a carbon number greater than 24. More preferably, it is desirable that less than 4% by weight of the hydrocarbon fraction of the LFP product has a carbon number greater than 24. 24 As described above, the Fischer-Tropsch (F-T) process generally produces hydrocarbon products with a chain length of 1 to 100 carbon atoms, having a majority within the wax range (C

[0053] However, the LFP catalyst used in the embodiments of this invention does not produce heavy hydrocarbons at the same yield as other catalysts used in conventional F-T processes. 24+ )). However, the LFP catalyst used in the embodiments of this invention does not produce heavy hydrocarbons at the same yield as other catalysts used in conventional F-T processes.

[0054] In some embodiments of the present invention, for the conversion of CO to CO2 via the water-gas shift reaction, the conversion activity is slight. In some embodiments of the present invention, the water-gas shift conversion of CO to CO2 is less than 5% of the CO in the feed. The LFP catalyst in some embodiments contains nickel as the active metal. The LFP catalyst in some embodiments contains cobalt as the active metal. The LFP catalyst in some embodiments contains both cobalt and nickel as the active metals. The LFP catalyst is supported on a metal oxide support selected from the group of alumina, silica, titania, activated carbon, carbon nanotubes, zeolites or other carrier materials or mixtures thereof, having a sufficient size, shape, pore diameter, surface area, crushing strength, effective pellet radius.

[0055] The catalyst can have a carrier with lobes of various shapes having three, four or five lobes, with two or more lobes being longer than the other two shorter lobes, and the longer lobes being symmetric with each other. The distance from the mid-point of the carrier or from the mid-point of each lobe is called the effective pellet radius and is an important parameter to achieve the desired selectivity to hydrocarbons. The promoter of the LFP catalyst may include one of cerium, ruthenium, lanthanum, platinum, rhenium, gold, nickel or rhodium. The promoter of the LFP catalyst is less than 1 wt% of the total catalyst, preferably less than 0.5 wt%, even more preferably less than 0.1 wt%. 24 In order to achieve the desired selectivity to hydrocarbons. The promoter of the LFP catalyst may include one of cerium, ruthenium, lanthanum, platinum, rhenium, gold, nickel or rhodium. The promoter of the LFP catalyst is less than 1 wt% of the total catalyst, preferably less than 0.5 wt%, even more preferably less than 0.1 wt%.

[0056] The carrier of the LFP catalyst has a pore diameter greater than 8 nanometers (nm), an average effective pellet radius of less than 60 micrometers (μm), a crushing strength greater than 3 pounds / mm, and a BET surface area wider than 125 m 2 / g. The catalyst after impregnation with the metal has a metal dispersion of about 4%. C4~C 24Several carriers have been found to maximize the hydrocarbon yield. These include alumina, alumina / silica combinations, activated carbon, carbon nanotubes, and / or zeolite-based carriers.

[0057] An LFP fixed bed reactor is operated to maximize the hydrocarbon yield. 24

[0058] Alternatively, in an LFP fixed bed reactor, a conventional F-T catalyst that produces mostly wax is used. The LFP reactor in one embodiment is operated at a pressure between 150 and 450 psi. The reactor is operated over a temperature range from 350°F (177℃) to 460°F (238℃) and more typically at about 410°F (210℃) . The F-T reaction is exothermic. The bundle of reactor tubes is placed inside a heat exchanger where there is boiling steam outside the tubes of the LFP reactor, thereby maintaining the temperature of the reactor inside the tubes of the LFP reactor. Since the temperature of the steam is lower than the LFP reaction temperature, heat flows from the tubes of the LFP reactor to the cooler steam. By maintaining the pressure of the steam, the temperature of the steam is maintained. The steam is generally saturated steam.

[0059] The conversion of CO in the LFP reactor is maintained between 30 and 80 mol% per pass. The CO can be recycled for additional conversion or sent to an additional downstream LFP reactor. The carbon selectivity to CO2 is minimized to less than 4%, more preferably less than 1% of the converted CO. The carbon selectivity to C4 - C 24 hydrocarbons is between 60 and 90%. The product gas from the LFP reactor contains the desired C4 - C 24 hydrocarbons, as well as unreacted carbon monoxide, hydrogen, water, small amounts of C1 - C5 hydrocarbons, and small amounts of C 24+ hydrocarbons. The desired product is separated from the stream by distillation or other acceptable means. Carbon Selectivity is defined as follows.​

[0060]

Number

[0061] Here, n CO Converted is the molar flow rate of CO converted in the LFP reactor, and n i is the molar flow rate of hydrocarbon with carbon number i generated in the LFP reactor. The carbon selectivity to carbon dioxide is defined as follows.

[0062]

Number

[0063] Here, n CO2 is the molar flow rate of CO2 generated in the LFP reactor. This is highly desirable for the production process of zero-carbon fuels and chemicals starting from carbon dioxide as a raw material.

[0064] The product is generated from the bottom of the reactor. Heavy hydrocarbons (C 24+) may be generated, so these products can be removed at the reactor outlet. When the LFP reactor is operated under appropriate conditions using a catalyst, there will be little heavy hydrocarbon. The main product of LFP is stream 16, which is cooled and condensed in unit 17. Unreacted carbon monoxide, hydrogen, and C1 - C5 hydrocarbons or tail gas (unit 18) are made part of the feed to the Auto-thermal Reformer (ATR). Figure 6 also shows the part of the auto-thermal reformer (ATR) (unit 19) for this method. In the auto-thermal reformer (ATR), the hydrocarbon feed to the ATR contains carbon monoxide, hydrogen, and C1 - C5 hydrocarbons. Auto-thermal reforming of natural gas mainly composed of methane (C1) into carbon monoxide and hydrogen has been commercially attempted for many years. See K. Aasberg-Petersen et al. / Journal of Natural Gas Science and Engineering 3(2011) 423-459.

[0065] In that it is desired to produce a product rich in CO with the ratio of the produced H2 to CO being between 1.9 and 2.2 mol / mol and the CO2 in the produced gas being less than 10 mol%, the ATR used in this invention is not necessarily conventional. The oxidant feed to the ATR contains steam and O2, and the O2 is at least partially generated by the electrolysis of H2O (stream 29). The oxidant feed to the ATR and the hydrocarbon feed to the ATR are preheated and then reacted in the ATR burner, where the oxidant and hydrocarbon are partially oxidized at a temperature in the range of 950 - 1,050 °C. The ATR reactor can be divided into three zones. In the combustion zone (or burner), at least a part of the hydrocarbon feed to the ATR is completely burned into H2O and CO2.

[0066] In the hot zone, further conversion is carried out by homogeneous gas-phase reactions. These reactions are slower than combustion reactions such as the oxidation of CO or pyrolysis reactions involving higher hydrocarbons. The overall main reactions in the hot zone are the steam reforming reaction and the shift reaction of hydrocarbons in the homogeneous gas phase. In the catalyst zone, the final conversion of hydrocarbons is carried out by heterogeneous catalytic reactions including the steam reforming of methane and the water-gas shift reaction. As a result, the product gas of the ATR has a composition close to the predicted thermodynamic equilibrium composition. The composition of the actual product gas of the ATR becomes the same as the thermodynamic equilibrium composition with a difference of less than 70°C. This is the so-called equilibrium approach temperature.

[0067] In order to minimize the amount of CO2 generated in the ATR, the amount of steam in the oxidant feed to the ATR needs to be kept as low as possible, although it results in a product gas of the ATR that is close to the predicted equilibrium composition and has less soot. Typically, in the combination of feeds (oxidant + hydrocarbon) to the ATR, the ratio (mol / mol) of the total amount of steam to carbon is desirably between 0.4 and 1.0, and optimally about 0.6.

[0068] The product of the ATR exits the catalyst zone of the ATR at a temperature higher than 800°C. The product of the ATR is cooled to a low temperature through a waste heat boiler (unit 22), where heat is transferred to generate steam. This steam can be used for power generation in the same way as the low-pressure steam generated by the LFP reactor.

[0069] ATR catalysts suitable for the reaction in the catalyst zone are typically nickel-based. The RWGS catalyst can be used as an ATR catalyst. Other suitable ATR catalysts are nickel on α-phase alumina or spinel of magnesium aluminate (MgAl2O4), which are used with or without a noble metal promoter, and this noble metal promoter includes gold, platinum, rhenium, or ruthenium. Spinel has a higher melting point, higher thermal strength, and stability than alumina-based catalysts.

[0070] The products of ATR can be mixed with the products of RWGS and used as a feed to the LFP reactor. This results in a high utilization rate for the original CO2 to hydrocarbon products. 24 This leads to a high utilization rate for hydrocarbon products.

[0071] In some embodiments, the product gas of LFP is not suitable as a direct feed to ATR and must be pre-reformed. In these cases, the product gas of LFP contains unreacted carbon monoxide, hydrogen, and C1-C5 hydrocarbons and includes a hydrocarbon feed gas to the pre-reformer. Generally, the higher hydrocarbons and carbon oxides in this stream need to use a pre-reformer instead of being directly used as a hydrocarbon feed to ATR. The pre-reformer is generally an adiabatic reactor. The adiabatic pre-reformer converts the higher hydrocarbons in the feed to this pre-reformer into a mixture of methane, steam, carbon oxides, and hydrogen, making it suitable as a subsequent hydrocarbon feed to ATR. One of the advantages of using a pre-reformer is that it can preheat the higher hydrocarbon feed to ATR and reduce the oxygen used in ATR. As a result, the integrated method as described above results in a high conversion from carbon dioxide to hydrocarbon products (stream 24) suitable as fuels or chemicals. 24 This leads to a high conversion to hydrocarbon products (stream 24).

[0072] The present disclosure includes the following matters. (1) An integrated method for converting a stream of feed including air, electricity, and water into a stream of product including hydrocarbons, a. An electrolysis step of converting a stream of feed of an electrolytic cell including water into a stream of product of the electrolytic cell including hydrogen and oxygen, wherein at least a part of the electricity used is from renewable resources, the electrolysis step; b. A direct air capture step of contacting air with an adsorbent to remove carbon dioxide from the stream of air; c. A reverse water gas shift step in which at least a part of the hydrogen from the stream of product of the electrolytic cell reacts with a stream including carbon dioxide from the direct air capture step to produce a stream of product of reverse water gas shift including carbon monoxide; d. A hydrocarbon synthesis step of reacting at least a part of the hydrogen from the stream of product of the electrolytic cell with a stream including at least a part of the stream of product of the reverse water gas shift to produce a stream of product of hydrocarbon synthesis; e. An autothermal reforming step of reacting at least a part of the oxygen generated by electrolysis with one stream or a plurality of streams including unreacted reactants from the hydrocarbon synthesis step; A method including the above steps. (2) The method described in (1) above, wherein the direct air capture uses an amine adsorbent supported on a solid. (3) The method described in (2) above, wherein the amine adsorbent supported on a solid is regenerated using the stream including hydrogen generated in the electrolytic cell. (4) The method described in (1) above, wherein in the direct air capture, carbon dioxide is removed from air using aqueous KOH. (5) The method described in (1) above, wherein the electrolytic cell is at location 1, the direct air capture is at location 2, and hydrogen from the electrolytic cell is transported from location 1 to location 2 by the LOHC method. (6) The method described in (1) above, wherein the raw material of the reverse water gas shift reactor is heated to at least 1,500°F (816°C) in an electric radiation furnace, the container of the reactor is a heat-insulated reactor, and the outlet temperature of the reactor is at least 100°F (56°C) lower than the inlet temperature of the reactor. (7) The feed to the reverse water gas shift reactor has a composition such that the molar ratio of hydrogen to carbon dioxide (H 2 (mol) / CO 2 (mol)) is 2.5 to 4.0. The method described in (1) above. (8) The feedstock for hydrocarbon synthesis has a molar ratio of hydrogen to carbon monoxide between 1.90 and 2.20, and C 4 ~C 24 selectivity is 70% or more, and C 24 The method according to (1) above, wherein the amount of carbon monoxide converted to products heavier than is less than 10%. (9) The method according to (1) above, wherein the autothermal reforming step includes steam as a feed, and the ratio of the steam to carbon is 0.40 to 1.00. (10) The method according to (9) above, wherein the catalyst for the autothermal reforming (ATR) includes a solid solution catalyst.

Claims

1. An integrated method for converting a stream of feed including air, electricity, and water into a stream of product including hydrocarbons, comprising: a. an electrolysis step of converting a stream of feed of an electrolytic cell including water into a stream of product of the electrolytic cell including hydrogen and oxygen, wherein at least a part of the electricity used is from renewable resources; b. a direct air capture step of contacting air with an adsorbent to remove carbon dioxide from the stream of air; c. a reverse water gas shift step in which at least a part of the hydrogen from the stream of product of the electrolytic cell reacts with a stream including carbon dioxide from the direct air capture step to produce a stream of product of reverse water gas shift including carbon monoxide; d. a hydrocarbon synthesis step of reacting at least a part of the hydrogen from the stream of product of the electrolytic cell with a stream including at least a part of the stream of product of the reverse water gas shift to produce a stream of product of hydrocarbon synthesis; e. an autothermal reforming step of reacting at least a part of the oxygen generated by electrolysis with one stream or a plurality of streams including unreacted reactants from the hydrocarbon synthesis step. A method comprising the above steps.

2. The method according to claim 1, wherein the direct air capture uses an amine adsorbent supported on a solid.

3. The method according to claim 2, wherein a stream including hydrogen generated in the electrolytic cell is used to regenerate the amine adsorbent supported on a solid.

4. The method according to claim 1, wherein in the direct air capture, aqueous KOH is used to remove carbon dioxide from air.

5. The method according to claim 1, wherein the electrolytic cell is at location 1, the direct air capture is at location 2, and hydrogen from the electrolytic cell is transported from location 1 to location 2 by the method of LOCH.

6. The method according to claim 1, wherein the raw material of the reverse water gas shift reactor is heated to at least 1,500°F in an electric radiant furnace, the container of the reactor is a heat-insulated reactor, and the outlet temperature of the reactor is at least 100°F lower than the inlet temperature of the reactor.

7. The method according to claim 7, wherein the feed to the reverse water gas shift reactor has a composition such that the molar ratio of hydrogen to carbon dioxide is 2.5 to 4.

0.

8. The feedstock for the hydrocarbon synthesis has a molar ratio of hydrogen to carbon monoxide between 1.90 and 2.20, and C ４ to C ２４ selectivity of 70% or more, and the amount of carbon monoxide converted to products heavier than C ２４ is less than 10%, the method according to claim 1.

9. The method according to claim 1, wherein the step of autothermal reforming includes steam as a feed, and the ratio of the steam to carbon is 0.40 to 1.

00.

10. The method according to claim 9, wherein the catalyst for ATR includes a solid solution catalyst.

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