KR102520557B1 - Method and apparatus for capturing carbon - Google Patents

Abstract

A carbon capture method and apparatus are provided. It converts carbon monoxide into carbon dioxide and polymerized carbon suboxide in the presence of non-thermal plasma (NTP). The carbon dioxide is converted into carbon monoxide by reacting with hydrogen through a reverse water-gas shift (RWGS) reaction.

Description

Carbon capture method and device {METHOD AND APPARATUS FOR CAPTURING CARBON}

The present invention relates to carbon capture, and more particularly to methods and apparatus for converting oxidized carbon to solidified carbon compounds.

Due to greenhouse gas emissions and global warming problems, the need to develop and spread renewable energy that can replace fossil fuels is increasing. Hydrogen is being considered as one of the clean energy sources. Hydrogen exists in many forms, including fossil fuels, biomass and water. In order to use hydrogen as a fuel, it is important to produce it economically as well as in a way that minimizes the impact on the environment.

Hydrogen production methods are divided into production through fossil fuel reforming reaction, which is a traditional method, and production using biomass and water, which are renewable methods. Hydrogen production using fossil fuels is possible through thermochemical methods such as wet reforming, autothermal reforming, partial oxidation, and gasification.

During the process of producing hydrogen, carbon dioxide is produced. Carbon dioxide is one of the representative greenhouse gases. Therefore, there is a need for carbon dioxide capture to reduce carbon dioxide emissions.

U.S. Patent No. 7,459,594 U.S. Patent No. 7,829,051

The present specification provides a method and apparatus for capturing carbon by converting carbon oxide into a solidified carbon compound.

In one aspect, the carbon capture method converts carbon monoxide into carbon dioxide and polymerized carbon suboxide in the presence of non-thermal plasma (NTP), and converts the carbon dioxide into carbon dioxide by a reverse water-gas shift (RWGS) reaction. It involves reacting with hydrogen to convert it to carbon monoxide.

In another aspect, the carbon capture device includes a first reactor for converting carbon monoxide into carbon dioxide and polymerized carbon suboxide in the presence of non-thermal plasma (NTP), and (b) converting the carbon dioxide into reverse water (RWGS). -gas shift) and a second reactor for reacting with hydrogen and converting it into carbon monoxide.

By converting the carbon oxides that may occur during hydrogen production into solidified carbon compounds, greenhouse gas emissions can be virtually eliminated. There is an additional advantage if hydrogen gas can be extracted from existing gas sources (natural gas, related gases, etc.) without carbon dioxide emissions. Methane, the main component of natural gas, is a greenhouse gas that is far more powerful than carbon dioxide. Natural gas is an abundant and inexpensive natural resource if it can be used environmentally.

1 shows the type of plasma, each electron temperature, and electron number density.
Figure 2 shows the effect of pressure on the equilibrium temperature of various species in the plasma.
Figure 3 shows plasma parameters that can be optimized to produce the desired excited species.
4 shows a schematic diagram of a hydrogen production method according to an embodiment of the present invention.
5 shows a schematic diagram of a hydrogen production method according to another embodiment of the present invention.
6 shows a schematic diagram of a hydrogen production device according to another embodiment of the present invention.
7 shows a schematic diagram illustrating an example of a plasma reactor.
8 shows a schematic diagram illustrating an example of a separator.

The term “plasma” generally refers to the ionized gas phase and is defined as a quasi-neutral gas of charged and neutral particles that collectively move in a similar way. "Quasi neutral" indicates the absence of a net charge within the macroscopic volume within the plasma. However, at the microscale, charge imbalances can exist. Certainly, within a plasma volume larger than the so-called "Debye sphere" there should be approximately charge neutrality, i.e. equality of the number of negatively and positively charged species. For example, at a pressure of 10 Torr and a field strength of 100 volts/cm, the electron density in a hydrogen glow discharge is about 3 Х 10 ¹⁰ electrons per centimeter cubed. The requirement for quasi-neutrality in the plasma requires that the ion density also be 3 Х 10 ¹⁰ per centimeter cubed. This represents an ionization degree of about 10 ^-7 since the number density of hydrogen in the discharge is about 3 Х 10 ¹⁷ molecules/cubic centimeter.

Unlike neutral gases, whose constituents are only affected by short-range interactions between gas particles (e.g., intermolecular collisions), distant parts of the plasma can affect other parts of the plasma. This property is because electromagnetic fields emitted from distant locations within the plasma can affect the charge carriers within it.

The plasma is maintained by an energy source (usually an electric field) of an appropriate size to produce a high concentration of ionized particles. The movement of a charged particle in an electric field is determined by the equation:

where v is the velocity of the particle, v ° = d v /d t , t is time, q is the charge of the particle, m is the mass of the particle, E is the electric field, and B is the magnetic field. This equation means that lighter particles are accelerated to a much higher degree than heavier particles in the same environment. For example, in the case of an electron with mass me and a proton with mass approximately 1836 me , the electron reaches a much higher velocity than the proton (hydrogen ion) when exposed to an electric field in a given unit time. In low-pressure plasmas, where the temperature of electrons can be much higher than that of heavier particles, this situation creates a non-equilibrium state in the plasma.

Plasma discharge types can generally be divided into two categories: equilibrium (thermal) plasmas or non-equilibrium plasmas. Equilibrium plasma involves an arc discharge and a plasma torch, whereas non-equilibrium discharge involves a wide range of plasma, with a greatly reduced electric field (electric field E divided by the gas density N) and a gas that equilibrates before the applied field changes. It is characterized by short time scales (or high frequencies) that prevent the species' internal energies (rotation, vibration and electrons). The reduced electric field (E/N) represents the plasma energy by controlling the factor dealing with the electron energy, which in turn determines the nature of the interaction between the electrons and the surrounding gas.

1 shows the type of plasma, each electron temperature, and electron number density.

Non-equilibrium plasmas can take the form of corona discharges, glow discharges, spark discharges, gliding arc discharges, dielectric barrier discharges (DBDs), and the like. Each type can be used with a variety of electrode configurations that greatly affect plasma characteristics. Key electrode characteristics include discharge gap distance, geometry of the electrode (which determines the localization of the discharge area) and material of construction. Gas parameters that also affect the type of discharge are pressure, temperature, internal energy composition of specific atoms and/or molecules in the gas, and flow rate/velocity.

The unique characteristics of plasma discharges in the context of equilibrium and non-equilibrium reaction environments must be considered. These considerations include the role of elastic and inelastic collisions within plasma and sheath physics. Electrons in a non-equilibrium plasma are much more mobile than ions (higher temperature, lower mass), resulting in a higher flux. Therefore, materials in contact with the plasma are generally negatively charged with respect to the plasma potential. The physics of the sheath refers to the structure of the non-neutral layer adjacent to the material in contact with the plasma.

Particles (eg ions, electrons, radicals and molecules) within the plasma interact with each other through collisions. When one particle collides with another, a reaction or excitation of one of the colliding particles may occur or cause an exchange of energy or momentum between the two particles. Under non-equilibrium conditions, electrons in the plasma move much faster than heavier species. Thus electrons can be regarded as incident species in collisions with heavier species that can be assumed to be at rest.

When an electron is incident on a rectangular volume in the plasma of unit side area and thickness Δx, the probability that the electron will collide with one of the target particles (eg hydrogen molecules) depends on the ratio of the area covered by the target particle. In general, the cross-sectional area for a given impact is not simply the projected area as in the case of a hard sphere impact. When particles interact by other means, such as electrostatic Coulombic forces, the cross-sectional area of impact can be quite different. The impact cross section also depends on the relative velocities of the incident and target particles. The following table outlines some possible interaction possibilities and their corresponding cross-sections.

The following equation represents the equilibrium dependence between electron T _e and the temperature of heavy particles for a reduced electric field E/n _h :

Here, ΔT represents the temperature difference between electrons and heavy particles. At low pressure (low number density n _h ), ΔT is large, so electrons are much hotter than heavier particles. In contrast, at high pressure (high concentration n _h ), ΔT is small, so electrons and heavy particles are in thermal equilibrium. Thus, the above equation describes the general operation shown in FIG. 2.

Figure 2 shows the effect of pressure on the equilibrium temperature of various species in the plasma. This represents the physical basis of the non-equilibrium behavior present in low-pressure plasmas, i.e. how electrons in a plasma discharge can be at such high temperatures compared to the temperature of the heavy particles.

In a non-equilibrium plasma, electrons are more excited than heavy ions by the electric field. Energy exchange between electrons and heavy particles is relatively inefficient due to the large difference in mass, and electrons in a non-equilibrium plasma have a higher temperature than heavy particles. On the other hand, heavier particles (i.e. ions, atoms, molecules, etc.) and electrons approach thermal equilibrium at increased pressure and reduced electric field strength. The higher temperatures reached by electrons in non-equilibrium plasmas give these plasma discharges new properties. For example, hot electrons in the plasma can produce high concentrations of excited species, such as atomic radicals or vibrationally excited molecules (via inelastic collisions), resulting in high levels of chemical activity in the plasma.

Heat loss to the environment is negligible because the heavy particles are at much lower temperatures. This contrasts with the situation of a high temperature (equilibrium) plasma where high chemical activity is achieved but the heat loss to the environment is very high. As such, high-temperature plasmas often require extensive cooling to allow for rapid quenching of the reaction products to prevent adverse reactions. Non-equilibrium plasmas reduce these limitations by simultaneously providing high reactivity and high thermal efficiency.

Finally, among the many unique properties of non-equilibrium plasmas is the effect of the non-equilibrium environment on the reaction pathways and corresponding reaction products produced. For example, nitrous oxide polymers can be formed in a non-equilibrium plasma during partial oxidation (POX) of methane. These species have not been observed to be present in the reaction products of methane POX in high-temperature (equilibrium) plasmas.

Excited species (eg ions, radicals or vibrationally/rotationally excited molecules) in the plasma are created when electrons collide inelastically with low-energy heavy species (ie ground state or metastable atoms or molecules). For example, a collision between an electron and a hydrogen molecule can create two hydrogen atoms through the following reaction:

Here, the kinetic energy of the fast electron induces the dissociation of the hydrogen molecule to the higher energy state of the two hydrogen atoms. This reaction can be visualized as a collision between an incident electron and a target hydrogen molecule. In general, the cross section of such an inelastic collision depends on the relative velocity of the incident electron and the target molecule. This relative velocity in turn depends on the parameters of the plasma discharge, in particular the reduced electric field E/n _h . The choice of plasma operating parameters has a significant impact on the energy efficiency of a particular process. Moving from 20 V to 100 V Torr-1 cm-1 changes the proportion of energy transferred from electrons to heavier species via elastic collisions by a factor of more than six.

Figure 3 shows plasma parameters that can be optimized to produce the desired excited species. For example, to maximize the dissociation efficiency that occurs within a hydrogen plasma (to produce atomic hydrogen), it would be advantageous to operate in the range of 30 to 50 V Torr-1 cm-1 given the two contributing dissociation mechanisms. will be.

Ionization is a specific case of an inelastic collision in which an incident electron knocks another electron out of a target particle. The electrically accelerated electrons ionize the neutral species and create more electrons. These daughter electrons accelerate themselves until they can induce further ionization and so on. This acceleration process produces a significant degree of ionization that defines the plasma.

As explained earlier, electrons have a higher average velocity than ions. Hence a given (neutral) surface will experience a higher electron flux than ions. This results in the development of a negative potential on ungrounded solids disposed in the plasma because there is a net flux of negative charge on the solid. When the magnitude of this potential increases, it repels electrons with low energy and attracts ions, generating a smaller negative current in the solid, bringing the potential of the solid closer to zero. Ultimately, this process reaches equilibrium and a steady-state potential is established. For ungrounded solids, this potential is called the floating potential. For a typical plasma, the floating potential can be as much as 10 to 30 volts lower than that of the bulk plasma. The floating potential is converted to the bulk plasma potential across a sheath, typically several Debye lengths thick.

A solid that is grounded or biased to a potential different from the floating potential will draw a net current. Quantifying the magnitude of the collected current as a function of bias voltage using a device called the Langmuir probe allows determination of several plasma parameters, including the electron temperature, T, and the concentration of ionized species in the plasma. Negative potentials can also be applied to solids with the intention of accelerating ions towards the surface. The effect of these highly accelerated ions on the solid surface is the chemical reaction that takes place on the solid surface.

Atmospheric-pressure low-temperature plasma (APLTP) operates in a non-equilibrium state under most operating conditions. One of the key features of APLTP is that the characteristic electron energy ranges from a few eV to 10 eV, while the heavy particle temperature varies from around room temperature to a similar, but generally lower, level to the electron temperature. This is due to the substantial physical mass difference between electrons and heavy particles (eg molecules, atoms and ions). There are three types of non-equilibrium APLTP: (i) Non-electrical-equilibrium (NEQ): When a conductive or non-conductive object is inserted into the plasma region, a sheath that is out of the quasi-charge neutral condition occurs between the surface of the object and the plasma region, and most of the total potential drop occurs in this NEQ region. Occurs. (ii) Non-local-thermodynamic-equilibrium (NLTE): The low mass ratio of electrons to heavy particles in the plasma (e.g. 10-5 for argon) leads to insufficient elastic energy exchange between electrons and heavy particles. (iii) Non-local-chemical-equilibrium (NLCE): Since the average electron temperature is around a few electron volts (eV) below the inelastic collision energy threshold of tens of electron volts (eV), excitation and ionization when interacting with cold gases Speed is particularly greatly reduced.

Carbon suboxide (C ₃ O ₂ ) is a carbon oxide and has a special structure in the form of a series of double bonds (O=C=C=C=O), so it is considered cumulene. Unlike general alkanes or alkenes, coumulin is more rigid than alkynes. Carbon dioxide's unique structure and rigidity make it suitable for molecular nanotechnology. Carbon dioxide's stiffness is possible because its intramural carbon atoms have two double bonds. The sp -hybridization of these carbon atoms results in the formation of two mutually perpendicular π bonds. This bonding process reinforces the linear geometry of the carbon chain. Carbon monoxide can be formed by applying a simple electric discharge to it.

Carbon dioxide, also known as "Tricarbon dioxide", is an oxide containing carbon in the oxidation state +4/3. It is called carbon dioxide because it has an oxidation state lower than that of CO or CO ₂ .

Due to the nature of the molecule in which three carbon atoms are bonded, a method for dehydrating an organic acid containing three carbon atoms is proposed. Since carbon dioxide is anhydride of malonic acid (HOOC-CH ₂ -COOH), one way to produce carbon dioxide is to dehydrate the acid with a strong dehydrating agent such as P ₄ O ₁₀ as follows: will be.

The reaction of C ₃ O ₂ with water produces malonic acid. Carbon dioxide is stable at low temperatures, but burns easily and polymerizes when heated.

When carbon is burned with excess air or oxygen, _CO2 is produced. However, when oxygen supply is limited, highly toxic CO is formed. Other higher carbon oxide CO or CO ₂ can also be formed indirectly. For example, carbon dioxide is produced from the dehydration of malonic acid, a three-carbon dicarboxylic acid, and the Lewis structures of these three oxides represent multiple structures:

At room temperature, carbon monoxide is a colorless, odorless, and tasteless gas with a boiling point of -192°C and a melting point of -205°C. The extreme toxicity of CO arises from the property of binding to iron ions in the hemoglobin molecule. Due to this property, the oxygen-carrying capacity of the blood is significantly reduced when CO is inhaled, resulting in an oxygen deficiency.

Carbon monoxide is an important industrial fuel;

It is also used as a reducing agent in metallurgy;

It is used as a reactant in the manufacture of important organic compounds.

Carbon dioxide is a colorless, odorless gas. When cooled at atmospheric pressure, it solidifies to become dry ice and sublimes at atmospheric pressure and a temperature of -78℃. All three physical states of CO ₂ are useful. More than half of the annual production is in the form of solid CO ₂ , which is used as a refrigerant, liquid CO ₂ as a propellant for aerosols, and gaseous CO ₂ mainly used in carbonated beverages.

Significant amounts of CO ₂ are used in manufacturing, which ranks in the top 13 US chemical production standards (by weight):

It is known that the formation of aliphatic hydrocarbons from iron-catalyzed CO ₂ hydrogenation proceeds as follows. First, CO ₂ is converted into CO through a reverse water-gas shift reaction (RWGS).

Hydrocarbon chains are then formed through the Fischer-Tropsch reaction.

However, in the presence of the Fe/Fe ₃ O ₄ nanocatalyst, aromatic products are formed through a series of reactions. The reaction between the two CO molecules causes a carbon laydown on the catalyst surface and forms CO ₂ through a Boudouard reaction.

Under certain reaction conditions, two CO molecules react stepwise with the newly deposited carbon on the catalyst to produce carbon dioxide (C ₃ O ₂ ).

C ₃ O ₂ is metastable and undergoes rapid polymerization at temperatures above 400°C. Under certain conditions, C ₃ O ₂ may be reduced to H ₂ C ₃ O ₂ by H ₂ instead of forming a polymer.

Dicarbon monoxide (C ₂ O) is a linear molecule containing two carbon atoms and one oxygen atom. Due to the inherent simplicity of the molecule, it has attracted interest in various fields. However, due to its high reactivity, it is not suitable for general environments. Carbon monoxide is a photolysis product of carbon monoxide.

Ketenylidene in organometallic chemistry is a ligand observed in metal carbonyl clusters such as [OC ₂ Co ₃ (CO) ₉ ] ⁺ . Kethenylidene is proposed as a mediator of the chain growth mechanism of the Fischer-Tropsch process that converts carbon monoxide and hydrogen into hydrocarbon fuels.

This specification relates to a method for converting natural gas (including sour gas/low quality natural gas) into high purity hydrogen gas without releasing harmful and greenhouse gases into the atmosphere. More specifically, the present specification relates to a method for converting and sequestering greenhouse gases such as carbon into solidified polymers, and preferentially producing hydrogen, which is the only product gas.

Energy production by reacting renewable sources of methane and hydrocarbons, such as natural gas, as well as landfill gas, digestion gas, and biosynthesis gas, with air and/or oxygen gas, yields a variety of carbon and sulfur containing products. Examples include carbon dioxide (CO ₂ ), carbon monoxide (CO), sulfur dioxide (SO ₂ ), hydrogen sulfide (H ₂ S), carbon disulfide (CS ₂ ), carbon sulfide (C ₃ S ₂ ) and carbonyl sulfide (COS). there is.

One way carbon monoxide is produced is by heating or burning graphite (one of the naturally occurring forms of elemental carbon) in the presence of a limited amount of oxygen. Reacting steam and red-hot coke produces carbon monoxide along with hydrogen gas (H ₂ ). Coke is an impure carbon residue formed when coal is burned. This mixture of CO and H ₂ is called water gas or syngas and is used as an industrial fuel or feedstock for organic synthesis. In the laboratory, carbon monoxide is produced by heating formic acid (HCOOH) or oxalic acid (H ₂ C ₂ O ₄ ) with concentrated sulfuric acid (H ₂ SO ₄ ). Sulfuric acid removes and absorbs water (H ₂ O) from formic acid or oxalic acid. As shown in the following reaction equation, carbon monoxide easily burns with oxygen to produce CO ₂ .

Carbon monoxide is useful as a gaseous fuel. In addition, since carbon monoxide has a property of reducing metal oxides such as copper oxide (CuO) and iron oxide (Fe ₂ O ₃ ) to elemental metals at high temperatures, it is also useful as a metallurgical reducing agent.

Carbon monoxide is a colorless, tasteless, and odorless gas, and is a very dangerous poisonous gas that is difficult to detect even if it leaks. Carbon monoxide's affinity for hemoglobin is 200 times higher than that of oxygen, and it easily replaces oxygen. Carbon monoxide combines with hemoglobin in the blood to form carboxyhemoglobin, which can be fatal to humans. Exposure to carbon monoxide destroys the ability of red blood cells to carry oxygen, causing hypoxia.

Carbon dioxide is produced when all forms of carbon or nearly all carbon compounds are burned in the presence of excess oxygen. Earth's atmosphere contains about 0.04% carbon dioxide by volume and serves as a huge CO ₂ reservoir. The carbon dioxide content of the atmosphere is increasing mainly due to the burning of fossil fuels. The so-called greenhouse effect is caused by an increase in carbon dioxide and water vapor in the atmosphere. These gases allow visible light from the sun to penetrate the Earth's surface, where it is absorbed and re-radiated as infrared radiation. This longer wavelength radiation is absorbed by _CO2 and water and cannot escape back into space. Increased heat in the atmosphere could increase the global average temperature by 2°C to 3°C. These changes have devastating effects on the environment and have major impacts on climate, sea level and agriculture.

Carbon dioxide (C ₃ O ₂ ) is a leaky, malodorous gas produced by the dehydration of malonic acid CH ₂ (COOH) ₂ and P ₄ O ₁₀ in vacuum at 140-150°C and contains a series of double bonds (O=C= It is a linearly symmetric molecule with a special structure in the form of C=C=O). At 25 °C it polymerizes as an unstable solid compound with a strong color, but it is a stable molecule at -78 °C. Polymerized carbon suboxide (PCS) is generally regarded as a material having a variable component because the carbon to oxygen ratio in the PCS is not constant.

C ₃ O ₂ is decomposed into highly reactive molecules, C ₂ O, under the influence of ultraviolet light. Carbon dioxide is an anhydride of malonic acid and reacts slowly with water to form malonic acid.

Methods have been proposed to use only the hydrogen component in all hydrocarbon fuels and keep the carbon as a solid waste or raw material. A big problem with this method is that only a small fraction of the available hydrocarbon chemical energy is actually utilized. For example, in the best case scenarios (14) and (15) of the process, only about half of the usable energy is actually converted and utilized compared to the energy produced in total methane oxidation, as shown in (16).

Suboxide polymers have a stable structure chemically and thermodynamically similar to humic acid, an organic component of fertile soil, and can be used as soil conditioners. Although biomass is commonly used as a fuel to reduce net carbon emissions, recent publications suggest that the use of agricultural land may offset the benefits of biomass fuels by releasing carbon stored in the soil. Recycling nitrous oxide polymers into agricultural soil not only mitigates soil carbon loss, but also provides the economic benefits of carbon sequestration (currently more than $80 per tonne of carbon).

To combat the potential environmental impact of carbon dioxide emissions, there is a need to increase the use of energy released from hydrocarbon fuels and reduce carbon dioxide emissions. The production of various carbon products in solid form can reduce carbon oxide production, thereby reducing air pollution as well as slowing the rise of greenhouse gases.

The application of non-thermal plasma for fuel conversion and H ₂ generation is particularly effective because the plasma is used not as an energy source but as a non-equilibrium generator of radicals and charged and excited particles. Plasma-generated active particles excite this process and contribute only a fraction (a few percent) of the total process energy.

Although the high energy efficiency plasma catalysis of partial oxidation processes is mostly related to specific heat release, industrial applications of this technology usually require relatively high productivity of syngas and relatively high output of applied emissions. The discharge of a gliding arc is well suited for this as it balances and retains mostly heat even at relatively high power levels. Particularly with respect to yield and energy efficiency, the CH ₄ partial oxidation process for syngas production is preferably using a non-equilibrium gliding arc discharge stabilized at atmospheric pressure in reverse vortex flow. has been shown to be effective. The flow pattern in this region provides the high gas velocities required for the movement of the non-equilibrium gliding arc and effective heat and mass exchange in the central region of the plasma.

Continuous conversion from unreacted to fully reacted CH ₄ /O ₂ /diluent mixture is possible by controlling plasma parameters and mixture composition. This successive transition is caused by an electron bombardment reaction that produces a mixture of electronically excited species, ions and atoms, all of which are rapidly quenched forming mostly O and H atoms and OH radicals. These radicals react with CH ₄ and intermediates and, depending on temperature, can lead to ignition of the mixture or partial oxidation of the fuel (CH ₄ ). While the power and magnitude of the reduced electric field (E/N) of the plasma affect the overall conversion, the product composition is strongly controlled by the chemical kinetics of the oxidation reaction at low temperatures (300–700 K).

Formation of a weakly ionized, radiating plasma in front of a weak shock wave propagating into an inert gas containing a mixture of reactive molecules is another way to achieve a non-equilibrium state. In this environment, the introduction of natural gas rich in H ₂ S (sour gas) causes the immediate dissociation of H ₂ S/CH ₄ and the formation of supersaturated vapors of sulfur and carbon atoms, followed by the formation of sulfurous oxides and C ₃ O ₂ clusters. A rapid formation follows. When strong energy is released during this process, non-equilibrium excitation and ionization occur.

Previous studies on ultraviolet, electrical discharge and microwave radiolysis of CO demonstrated that CO decomposes to produce CO ₂ and a carbonaceous solid. The average experimental composition of the solid formed at 20 °C is given by the ratio x/y = 1.45±0.07 in the equation (C _x O _y ) _n . To simplify notation, this solid is hereafter referred to as (C ₃ O ₂ ). There is also evidence of accumulation of C ₃ O ₂ from C to C ₂ O and C ₃ O ₂ . This mechanism has been shown to dominate in the photochemistry of CO. In addition, the reaction between C atoms and C ₂ O has been proposed to explain the excitation of the C ₂ high-pressure band observed during radiation of helium + CO mixtures.

In previous studies on the photolysis of C ₃ O ₂ , it was shown that species reacting with various hydrocarbon gases, such as olefins, in which C atoms are inserted into double bonds, are mainly produced. This species appears to be a radical C ₂ O. Low-pressure operation in a fast-flow system shows that C ₃ O ₂ reacts with O atoms in a rapid reaction to produce CO and CO ₂ as products. In addition, chemiluminescence of excited CO as high as ~9 eV is observed. This high energy is hypothesized to come from the reaction of C ₂ O with O atoms.

In all the examples above, the radical C ₂ O plays an important role as a building block of C ₃ O ₂ or as a reactive intermediate in photolysis or chemical C ₃ O ₂ decomposition.

Carbon dioxide can be formed by the action of a discharge on CO. Consider the following reaction for suboxide formation.

When the suboxide is heated in a nitrogen atmosphere, another brown oxide is formed as

CO can be decomposed in an ozone generator by the following decomposition reactions:

Alternatively, using an alternating electric field of 250 c/s (cycles per second) and 20,000 V/cm, CO can be decomposed as follows:

Using both aluminum and iron electrodes, CO can produce CO ₂ and carbon dioxide in the glow discharge. As shown in the following equation, CO can be decomposed using high-speed electrons generated in a cathode ray tube.

No precipitate forms in the presence of water vapor. Radon emission can be used to break down CO into carbon and oxygen. The following equation represents CO decomposition by α-particles.

The precipitate obtained is insoluble in water, acid or alkali, but disappears slowly in concentrated nitric acid or concentrated potassium hydroxide. A stoichiometric mixture of CO and O ₂ gives only CO ₂ , and an excess of either does not affect the reaction rate.

In one embodiment of the present disclosure, a method for producing hydrogen with low greenhouse gas emissions is provided. In another embodiment of the present specification, a method for preparing a solidified carbon compound by treating carbon oxide is provided.

4 shows a schematic diagram of a hydrogen production method according to an embodiment of the present invention.

Natural gas is input as an energy source to the first unit 410 . Natural gas is an example of an energy source. The energy source may include hydrocarbon gas. The hydrocarbon gas may include natural gas, liquefied petroleum gas (LPG), methane, propane, biogas, and pyrogas (biomass pyrolysis gas). In the following, methane, which is the main component of natural gas, will be described as an example of an energy source.

Air is introduced into the first unit 410 . In the first unit 410, natural gas reacts with air by partial oxidation (POX) as shown in the following equation, and syngas is discharged.

Syngas is a mixture of CO and H ₂ . Syngas may further contain a small amount of CO ₂ . The first unit 410 may be a POX reactor that performs POX. Catalysts (metal catalysts, plasma catalysts or combinations thereof) may be used for POX.

Syngas is input to the second unit 420 . Syngas is split into H ₂ and CO, and H ₂ is released. Chemical absorption may be performed to separate the syngas. The separated CO is converted into solidified carbon dioxide and carbon dioxide in the presence of plasma as shown in the following equation. The plasma may include non-thermal plasma (NTP).

Solidified carbon compounds can be directly obtained from CO obtained from natural gas. The production of gaseous carbon oxides is reduced by preferential formation of solidified carbon monoxide at the same time that hydrogen is released from the hydrocarbon source. In particular, solidified carbon dioxide can be used as a fertilizer (eg, a soil improver) and does not require separate storage or treatment.

The first unit 410 and the second unit 420 may be designed as independent reactors or separate compartments, or as one reactor.

5 shows a schematic diagram of a hydrogen production method according to another embodiment of the present invention.

In the first unit 510, natural gas reacts with air by POX and is discharged as syngas. The first unit 510 may be a POX reactor. Catalysts (metal catalysts, plasma catalysts or combinations thereof) may be used for POX.

Syngas is separated into H ₂ and CO in the second unit 520 . The second unit may perform a chemisorption process such as pressure swing adsorption (PSA).

In the third unit 530, CO is converted into solidified carbon monoxide and a small amount of carbon dioxide in the presence of NTP. The third unit 530 may be an NTP reactor such as a gliding arc discharge (GAD) or dielectric barrier discharge (DBD) system.

CO ₂ released from the third unit 530 is converted into CO along with hydrogen in the fourth unit 540 as shown in the following equation. Hydrogen may be obtained from the output of the second unit 520 . The fourth unit 540 may be a reactor that performs reverse water-gas shift reaction (RWGS).

The obtained CO is input again to the third unit 530 to react as shown in Chemical Formula (24).

Emissions of CO and CO ₂ obtained as a by-product of the reaction to obtain hydrogen gas can be almost eliminated.

The first unit 510 to the fourth unit 540 may be designed as at least one reactor or at least one compartment.

6 shows a schematic diagram of a hydrogen production device according to another embodiment of the present invention.

The hydrogen production device 600 includes a POX reactor 610, a PSA unit 620, a plasma reactor 630, a separator 640, and an RWGS reactor 650.

Natural gas (eg, CH ₄ ) is guided to the POX reactor 610 via a heat exchanger 615 . Air is also input to the POX reactor 610 separately from natural gas. POX reactor 610 performs partial oxidation. Partial oxidation can occur without a catalyst. Partial oxidation may occur in the presence of at least one of a metal catalyst, a plasma catalyst, and a combination thereof. The metal catalyst may include a granular catalyst such as nickel oxide supported with ferric oxide.

The POX reactor 610 may operate intermittently. In the first cycle, only natural gas enters and reacts with a catalyst to generate H ₂ and CO discharged from the reactor 610. This catalyst may be a renewable redox catalyst. In the second cycle, the flow of CH ₄ is captured and air is introduced into the reactor 610 to reoxidize the catalyst to its original state and burn and remove the residual coke to regenerate the catalyst.

Partial oxidation in POX reactor 610 may occur at a temperature within the range of 300°C to 700°C (preferably, 400°C to 600°C). Energy consumption can be reduced by performing partial oxidation at a relatively low temperature around 500°C.

A plasma reactor 630 described below may be disposed within the POX reactor 610 . A synergistic effect exists between the plasmatron and the redox catalyst, allowing partial oxidation of CH ₄ at significantly lower reaction temperatures. One reason to use POX instead of Steam Methane Reforming (SMR) is that it can operate in the endothermic or exothermic (or autothermal for that matter) regime, and at low temperatures (600°C or less) if an appropriate catalyst is used (with plasma). because it can work very efficiently.

The POX reactor 610 may be charged with granular iron oxide supported nickel (Fe ₂ O ₃ /NiO) or any number of transition metal oxide supported Ni and/or noble metal catalysts. POX reactor 610 may be operated in a chemical cycle regime. An advantage of this approach is to mitigate the carbon laydown without excessive introduction of O ₂ into the reactor 610 or the necessary temperature rise. Operating the reactor 610 in a chemical circulation mode has an advantage of preventing dilution of the output gas (syngas) by nitrogen (N ₂ ) removal. In other words, the syngas leaving the POX reactor 610 contains only CO, H ₂ and traces of CO ₂ .

Hot syngas exiting POX reactor 610 may exchange heat with natural gas and/or air entering through heat exchanger 615 before entering PSA unit 620.

PSA unit 620 separates compounds of hydrogen and CO from natural gas through PSA. High purity hydrogen is recovered and stored. Except for hydrogen, most of the gases exiting the PSA unit 620 are CO.

Plasma reactor 630 converts CO to solidified carbon monoxide in the presence of NTP. Plasma reactor 630 converts CO to solidified carbon monoxide via NTP assisted reforming. The CO-rich gas may be irradiated with high-temperature electrons while passing through the plasma reactor 630 to be converted into a mixture of carbon black and carbon dioxide. Also, some CO ₂ may be produced. The plasma reactor 630 may be a gliding arc discharge (GAD) system or a dielectric barrier discharge (DBD) system.

The separator 640 separates CO ₂ and solidified carbon compounds from the gas and mixture discharged from the plasma reactor 630 . Separator 640 may be a cyclone separator.

The CO ₂ gas discharged from the separator 640 is reduced together with hydrogen in the RWGS reactor 650 to form CO and returned to the plasma reactor 630 .

In the foregoing embodiment, hydrocarbons (eg, CO, CO ₂ , etc.) may be converted into solidified carbon compounds in the presence of a low-temperature plasma in the plasma reactor 630 . In the plasma reactor 630, hydrocarbons (eg, CO, CO ₂ , etc.) can be converted into solidified carbon compounds through NTP-assisted reforming. Applicable to carbon capture without hydrogen production.

Emissions of CO and CO ₂ obtained as a by-product of the reaction to obtain hydrogen gas can be almost eliminated.

7 shows a schematic diagram illustrating an example of a plasma reactor. The plasma reactor 700 uses DBD plasma. The plasma reactor 710 includes at least one DBD unit 710, and each DBD unit 710 includes a plurality of DBD cells 711.

8 shows a schematic diagram illustrating an example of a separator. Separator 800 is a cyclone separator. A mixture of CO ₂ gas and solidified carbon compounds is introduced into separator 800 . Solids are discharged to the bottom of the separator 800 via a vortex configuration. The CO ₂ gas is discharged to the top of the separator 80 .

Claims (4)

(a) converting carbon monoxide into carbon dioxide and polymerized carbon suboxide in the presence of non-thermal plasma (NTP); and
(b) converting the carbon dioxide into carbon monoxide by reacting with hydrogen by a reverse water-gas shift (RWGS) reaction;
In order to capture the maximum amount of carbon generated, inputting carbon dioxide generated in step (a) into step (b) and inputting carbon monoxide generated in step (b) into step (a) is repeated at least once. A carbon capture method, characterized in that. According to claim 1,
(c) the carbon capture method further comprising converting the carbon monoxide into carbon monoxide solidified in the presence of the NTP. According to claim 1,
The carbon capture method, characterized in that the carbon monoxide and the solidified carbon monoxide of step (a) are separated by a cyclo separator. A first reactor for converting carbon monoxide into carbon dioxide and polymerized carbon suboxide in the presence of non-thermal plasma (NTP); and
A second reactor for converting the carbon dioxide into carbon monoxide by reacting with hydrogen by a reverse water-gas shift (RWGS) reaction,
In order to maximally capture the generated carbon, it is at least necessary to input the carbon dioxide generated in the first reactor into the second reactor and input the carbon monoxide generated in the second reactor into the first reactor again. A carbon capture device characterized in that it is repeated one or more times.

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