Carbon dioxide conversion apparatus and method

Abstract

The present invention relates to a process for converting carbon dioxide to carbon monoxide, the process comprising: generating atomic oxygen, providing carbon dioxide to be converted, mixing the carbon dioxide with the atomic oxygen in a mixing zone such that the atomic oxygen can interact with the carbon dioxide to react by means of a first CO generation: CO2 + O-CO + O2 forms carbon monoxide in the mixing zone, supplying atomic oxygen into the mixing zone at a first supply rate and carbon dioxide into the mixing zone at a second supply rate, the first supply rate and the second supply rate being defined such that a ratio between the first supply rate and the second supply rate remains within predefined upper and lower threshold values, and extracting carbon monoxide from the mixing zone. The present disclosure also relates to an apparatus for converting carbon dioxide to carbon monoxide.

Description

Technical Field

[0001] The present disclosure relates to an apparatus and method for converting carbon dioxide into carbon monoxide. Background Art

[0002] In light of climate change and global warming, converting carbon dioxide gas into valuable products has become a major topic of energy and environmental research.

[0003] This strategy of reusing emitted CO2, e.g. from recapture or directly from exhaust gases, and converting it into products of industrial interest is also known as Carbon Capture and Utilization, CCU.

[0004] Over the years, many CCU methods have been developed: electrochemical conversion, solar thermochemical conversion, biochemical conversion, photochemical conversion, etc. Each of these methods has its advantages, but they all face different difficulties related to, for example, chemical instability, the use of rare materials, and cultivation problems. These methods are able to convert CO2, but usually require complex setups, resulting in high investment costs, and often limited possibilities for scale-up.

[0005] Another method is the gas reforming process, in which CO2 is used in gaseous form without the addition of non-gaseous products required for the reforming, such as bound metals.

[0006] A known method for CO2 gas conversion is thermal conversion, which allows the conversion of carbon dioxide into carbon monoxide with high conversion rates. However, the main disadvantage of thermal conversion is the low conversion efficiency. This is due to the stability of the CO2 molecule and the large amount of energy required to break the CO2 double bond. In fact, the conversion reaction, CO2→CO+O is highly endothermic, with a standard enthalpy ΔH° of 5.5 eV / molecule. In order to effectively convert CO2 by thermal conversion, temperatures in the range of 3000°K to 4000°K are required.

[0007] Another promising CO2 gas conversion method is plasma-assisted CO2 conversion. In fact, plasma technology allows the direct decomposition of CO2 gas into CO and O by, for example, electron impact dissociation or dissociation after a vibration ladder process. Various types of plasma reactors have been proposed for plasma-based CO2 conversion, such as those discussed by Snoeckx and Bogaerts in Chem. Soc. Rev. 2017, 46, 5805.

[0008] Although various types of plasma reactors have shown promising results in CO2 conversion, further improvements are still needed in order to make plasma reactor technology commercially attractive for large-scale applications. In particular, further research is needed to increase conversion efficiency while minimizing energy consumption, also known as energy cost.

[0009] Therefore, there is room for alternative methods and apparatuses for carbon dioxide conversion. Summary of the invention

[0010] It is an object of the present disclosure to provide an alternative cost-effective and simple method and apparatus for converting carbon dioxide into carbon monoxide, wherein high conversion efficiencies are obtained.

[0011] The invention is defined in the appended independent claim. The dependent claims define advantageous embodiments.

[0012] According to a first aspect of the present invention, there is provided a method for converting carbon dioxide into carbon monoxide.

[0013] In one embodiment, the method includes providing carbon dioxide to be converted, generating atomic oxygen, mixing the carbon dioxide with the atomic oxygen in a mixing zone so that the atomic oxygen can interact with the carbon dioxide to generate a reactive CO via a first CO 2 +O→CO+O 2 Carbon monoxide is formed in the mixing zone and is exhausted from the mixing zone.

[0014] In another embodiment, the first supply rate (S) of atomic oxygen is defined as O ) and the second supply rate of carbon dioxide (S CO2 ), such that:

[0015] R1 O / (S O +S CO2 ) <R2

[0016] Wherein R1 and R2 are a predefined lower threshold and a predefined upper threshold, respectively, wherein R1 ≥ 0.1 and R2 ≤ 0.9, preferably R1 ≥ 0.2 and R2 ≤ 0.8, more preferably R1 ≥ 0.3 and R2 ≤ 0.7.

[0017] The method preferably comprises: providing carbon dioxide to be converted, generating atomic oxygen and defining a first supply rate (S O ) and the second supply rate of carbon dioxide (S CO2 ), so that: R1 O / (S O +S CO2 ) <R2,S O and S CO2 are respectively a first supply rate and a second supply rate, and wherein R1 and R2 are respectively a predefined lower threshold and a predefined upper threshold.

[0018] ​​The method according to the present disclosure also preferably includes: mixing carbon dioxide with atomic oxygen in a mixing zone so that the atomic oxygen can interact with the carbon dioxide to produce a reaction through a first CO:CO 2 +O→CO+O 2 Carbon monoxide is formed in the mixing region, and atomic oxygen and carbon dioxide are supplied into the mixing region at a first supply rate and a second supply rate, respectively, and carbon monoxide is exhausted from the mixing region.

[0019] As used herein, the term "exhaust" refers to the process of "removing," "extracting," or "transferring" carbon monoxide from the mixing area (MA), preferably through a gas outlet.

[0020] The first supply rate of atomic oxygen must be interpreted as a first number of oxygen atoms supplied per unit time in the mixing region and the second supply rate of carbon dioxide must be interpreted as a second number of carbon dioxide molecules supplied per unit time in the mixing region.

[0021] The atomic oxygen based carbon dioxide conversion process according to the present disclosure has several advantages over prior art carbon dioxide conversion processes.

[0022] For example, the method of the present invention does not require the processing of any rare materials, and the conversion process can be turned on and off simply by turning the production of atomic oxygen on and off, which allows the method to be used advantageously in conjunction with renewable energy sources.

[0023] Advantageously, no external energy is supplied to the mixing zone. The only energy required is for the generation of atomic oxygen.

[0024] By generating atomic oxygen and contacting it together with the carbon dioxide to be converted in a mixing zone, carbon monoxide can be advantageously converted via a less energy intensive conversion reaction: CO 2 +O→CO+O 2 The standard enthalpy ΔH° is 0.3 eV / molecule.

[0025] In addition, atomic oxygen will also recombine into molecular oxygen in the mixing region, thereby releasing energy. In fact, the oxygen recombination reaction O+O→O 2 It is a highly exothermic reaction with a standard enthalpy ΔH° of -5.2 eV / molecule, so even if initially starting from a mixing region at room temperature, the temperature of the mixing region will quickly increase to hundreds of Kelvin in less than a millisecond, allowing the above-mentioned endothermic CO2 conversion reaction to occur.

[0026] By controlling the ratio between the atomic oxygen supply rate and the carbon dioxide supply rate to be converted, as claimed in the present patent, the occurrence of the oxygen recombination reaction can be controlled, and thus the temperature of the mixing zone can be controlled. Advantageously, by controlling the atomic oxygen supply rate and the carbon dioxide supply rate, the temperature T in the mixing chamber is m Can be kept below 2500°K, for example 800°K≤T m ≤2500°K. In this way, the CO2 thermal conversion limit of about 3000°K is not reached, and the other CO2 conversion reaction is suppressed compared to the first CO2 conversion reaction with a much lower standard enthalpy: CO 2 +M→CO+O+M, where the standard enthalpy ΔH° is 5.5 eV / molecule and M is any neutral molecule.

[0027] According to a second aspect of the present invention, there is provided an apparatus for converting carbon dioxide into carbon monoxide. The apparatus comprises an atomic oxygen generator for generating atomic oxygen; a mixing region configured to mix the generated atomic oxygen with the carbon dioxide to be converted so that when the apparatus is in operation, the atomic oxygen can interact with the carbon dioxide in the mixing region to convert the carbon monoxide through a first reaction: 2 +O→CO+O 2 to form carbon monoxide; a carbon dioxide supplier configured to supply the carbon dioxide to be converted to the mixing zone; a control device configured to control a first supply rate of atomic oxygen supplied to the mixing zone and to control a second supply rate of carbon dioxide supplied to the mixing zone; and a gas outlet configured to exhaust carbon monoxide from the mixing zone.

[0028] Since the subject matter of the independent device claim allows the implementation of the carbon dioxide conversion method specified in the independent method claim, the advantages of the method described above also apply to the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] These and other aspects of the present disclosure will be explained in more detail by way of example and with reference to the accompanying drawings, in which:

[0030] Figure 1 A block diagram showing method steps included in the method according to the present disclosure,

[0031] Figure 2 The carbon dioxide conversion method according to the present disclosure is schematically shown.

[0032] Figure 3a shows the variation of carbon dioxide conversion efficiency over time according to the present disclosure for different ratios between atomic oxygen supply and carbon dioxide supply,

[0033] Figure 3bshows the time variation of the gas temperature in the mixing region for different ratios between the atomic oxygen supply and the carbon dioxide supply,

[0034] Figure 3c is a comparison between the carbon dioxide conversion efficiency obtained by the method of the present invention and the efficiency obtained by using classical hot gas conversion,

[0035] Figure 3d shows the variation of carbon dioxide conversion efficiency with time for various pressure conditions in the mixing zone,

[0036] Figure 4a The relationship between the carbon dioxide conversion efficiency and the ratio of supplied atomic oxygen to supplied molecular oxygen for different CO2 fractions is shown.

[0037] Figure 4b shows the relationship between the temperature in the mixing region and the ratio of supplied atomic oxygen to supplied molecular oxygen for different CO2 fractions,

[0038] Figure 5 Schematically showing an embodiment of an apparatus for carbon dioxide conversion according to the present disclosure,

[0039] Figure 6 An embodiment of an apparatus for carbon dioxide conversion according to the present disclosure is schematically shown, wherein the atomic oxygen generator is a plasma generator.

[0040] The drawings are neither drawn to scale nor are they to proportion. Generally, identical components are denoted by the same reference numerals in the drawings. DETAILED DESCRIPTION

[0041] The present disclosure will be described according to specific embodiments, which are illustrative of the present disclosure and should not be construed as limiting. It will be understood by those skilled in the art that the present disclosure is not limited by the content specifically shown and / or described, and that alternative or modified embodiments may be developed based on the overall teachings of the present disclosure. The accompanying drawings described are only illustrative and not restrictive.

[0042] Use of the verb "comprise" and its conjugations does not exclude the presence of elements other than the stated elements. Use of the article "a", "an" or "the" preceding an element does not exclude the presence of a plurality of such elements.

[0043] In addition, the terms first, second, etc. in the specification and claims are used to distinguish similar elements and are not necessarily used to describe a sequence in time, space, order, or in any other manner. It should be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the present disclosure described herein are capable of operating in other sequences than those described or shown herein.

[0044] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present disclosure. Therefore, the phrases "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily all refer to the same embodiment, but may also refer to the same embodiment. In addition, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure.

[0045] Methods for CO2 conversion

[0046] According to a first aspect of the present disclosure, a method for CO2 conversion is provided. Figure 1 , shows a block diagram, wherein steps 1 to 5 show method steps performed using the carbon dioxide conversion method according to the present disclosure.

[0047] The carbon dioxide conversion method according to the present disclosure includes a first step 1 of providing carbon dioxide to be converted and a second step 2 of generating atomic oxygen.

[0048] In an embodiment, the CO2 to be converted is in a gaseous state.

[0049] As mentioned above, the CO 2 to be converted may be, for example, CO 2 from recaptured CO 2 or directly from the exhaust gas from which the CO 2 was generated.

[0050] When introducing various methods of generating atomic oxygen, the second step 2 of generating atomic oxygen will be discussed in more detail below.

[0051] In step 4, CO2 and CO are mixed in the mixing area MA, as Figure 2 Shown 2.

[0052] By the method of the invention, CO2 and O are supplied to the mixing zone at a well-defined O / CO2 ratio. Therefore, the method of the invention comprises, in step 3, defining a first supply rate S of atomic oxygen. O And define the second supply rate S of carbon dioxide CO2 The first and second supply rates are defined so that the ratio between the first supply rate and the sum of the first supply rate and the second supply rate is contained within a predefined lower threshold R1 and a predefined upper threshold R2. In other words, R1 O / (S O +S CO2 ) <R2,S O is the first supply rate of atomic oxygen, S CO2 is the second supply rate of carbon, where R1 and R2 are predefined lower and upper thresholds, respectively. ​

[0053] Typically, the first supply rate and the second supply rate correspond to the number of oxygen atoms and the number of carbon dioxide molecules supplied to the mixing area MA per unit time, respectively. However, the supply rate may also be expressed in other units.

[0054] What the values ​​of R1 and R2 are, or how to select these values, will be discussed in more detail below. Typically, R1 ≥ 0.1 and R2 ≤ 0.9, preferably R1 ≥ 0.2 and R2 ≤ 0.8, more preferably R1 ≥ 0.3 and R2 ≤ 0.7. Therefore, the first supply rate of atomic oxygen should be at least lower than the second supply rate of carbon dioxide.

[0055] In step 4, when the first supply rate S O and the second supply rate S CO2 When atomic oxygen and carbon dioxide are supplied into the mixing area MA, carbon dioxide will be mixed with atomic oxygen in the mixing area MA, and thus atomic oxygen can interact with carbon dioxide to react through the first CO generation, namely: CO 2 +O→CO+O 2 , carbon monoxide is formed in the mixing area MA. Therefore, the CO2 conversion method of the present invention can also be called an atomic oxygen driven CO2 conversion method.

[0056] Finally, in step 5, CO is discharged from the mixing zone. Typically, not only CO is discharged, but also product gas is discharged from the mixing zone MA, the product gas comprising at least CO. Product gas must be interpreted as the various substances present in the mixing zone and, in addition to CO, may also include, for example, unconverted CO2 or other gases present in the mixing zone, such as O2.

[0057] like Figure 2 As schematically shown, the gas temperature T in the mixing area MA can be determined m and gas pressure P m .

[0058] To demonstrate the CO2 conversion rates achievable with the atomic oxygen driven CO2 conversion method of the present invention, model calculations were performed in which CO2 and O began to be supplied and mixed in the mixing region at time t=0, and in which the changes in the mixture varied over time. The model takes into account thermoneutral chemistry. For example, the model calculates the change in density of a homogeneous uniform volume element over time, including gas heating. Various species are included in the model, such as neutral ground state species, charged species, and exit species. In the first set of calculations performed, no external power was applied to the mixing region.

[0059] Figure 3a to Figure 3d The first set of calculation results is shown in which no external heat is applied. Figure 3aIn the figure, the CO2 conversion, expressed as a percentage of the converted CO2, is shown as a function of time. Figure 3a For different S values ​​of 10%, 30%, 50%, 70% and 90%, O / (S O +S CO2 ) ratio, showing five curves. Initially, the conversion is low, but then increases rapidly to a maximum. For the lowest 10% S O / (S O +S CO2 ) ratio, CO2 conversion rate is very low. Figure 3a The linear range is not visible. O / (S O +S CO2 ) ratio, after reaching the maximum conversion rate, it reaches a plateau of about 10% CO2 conversion rate. O / (S O +S CO2 ) ratio, can reach a maximum conversion value of almost 100%. However, in this example, O / (S O +S CO2 ) ratio of about 50%, where a maximum yield of about 45% is obtained, and, for example, after a time period of 10 milliseconds, a steady-state condition is obtained, where the conversion remains constant over time. In contrast, for example, 70% or 90% S O / (S O +S CO2 ) ratio, where a higher maximum conversion is achieved, but steady-state conditions cannot be achieved, so the conversion continues to decrease over time after reaching the maximum value. In order to apply the CO2 conversion method of the present invention in an industrial device, a conversion rate that reaches steady-state conditions is more practical. Therefore, this emphasizes the importance of clearly defining and controlling the ratio S O / (S O +S CO2 ) to obtain the importance of the CO2 conversion curve that reaches steady-state conditions.

[0060] exist Figure 3b In Figure 3a The same S O / (S O +S CO2 ) ratio, the gas temperature T in the mixing region m is shown as a function of time. The curve shows an initial increase in temperature until a maximum temperature is reached. O / (S O +S CO2) ratio, after reaching the maximum temperature, the temperature drops sharply with time, as shown for example at the 70% and 90% curves. O / (S O +S CO2 ) ratio, after the maximum temperature the temperature remains more or less constant, as shown by the 10% curve. For S between 30% and 60% O / (S O +S CO2 ) ratio, after reaching the maximum temperature, the temperature changes only slowly with time.

[0061] By the method according to the present disclosure, in the mixing zone an exothermic recombination reaction, namely: O+O→O 2 Heat is generated, and the standard enthalpy of the reaction, ΔH°, is -5.2 eV / molecule. Therefore, even without any external heating, the gas temperature in the mixing region, T m It can also reach thousands of Kelvin, such as Figure 3b shown.

[0062] Even if it is initially started at room temperature, the temperature in the mixing chamber will increase due to this exothermic atomic oxygen recombination reaction. Figure 3b As shown, S O / (S O +S CO2 ) ratio, the higher the temperature that can be achieved in the mixing zone. For higher S O / (S O +S CO2 ) ratio, the temperature will reach over 3000°K, which means that the thermal conversion limit of CO2 has been reached.

[0063] When a high temperature of 3000°K or higher is reached, thermal conversion of CO2 occurs, thereby generating reactive CO in the mixing zone by a second CO 2 +M→CO+O+M (ΔH°=5.5 eV / molecule) produces CO, where M is any neutral molecule, ie, any neutral molecule present in the mixed region.

[0064] When the temperature is low, such as at 2000°K, the production of CO in the mixing zone is dominated by the first CO production reaction. Figure 3c , where the conversions obtained with the method according to the present disclosure at 50% and 90% O supply were compared with pure thermal CO2 conversion at fixed temperatures of 2000°K and 4000°K, the latter being obtained with a classical thermal CO2 conversion method using a heating source to heat the CO2 to be converted. Using the present method, a maximum conversion of up to 99% was obtained at 90% O supply, which is similar to the conversion obtained with the classical thermal conversion at 4000°K. However, as Figure 3bAs shown, at 50% O supply, the temperature of the mixing zone is about 2000°K and the maximum conversion obtained is about 40%, which is in sharp contrast to the classical thermal conversion at the same temperature of 2000°K, where the CO conversion is less than 1%.

[0065] exist Figure 3c The CO conversion rate of thermal conversion is less than 1% at 2000°K. Figure 3c This is not visible on the linear scale used. This demonstrates that, using the process of the present invention by adding atomic oxygen to CO2, higher conversions can be obtained at lower temperatures (eg, 2000°K) due to the first CO production reaction described above.

[0066] Figure 3b The various curves shown indicate that the gas temperature T in the mixing region m Supply ratio S O / S CO2 Therefore, by defining S in step 3 of the method of the present invention O / (S O +S CO2 ) ratio, and can also control the temperature T in the mixing area m .

[0067] In an embodiment, the method according to the present disclosure further comprises obtaining the gas temperature T in the mixing area MA m The step is included in 500°K≤T m ≤3000°K, preferably 800°K≤T m ≤2500°K, more preferably 1000°K≤T m ≤2500°K. In this way, the first CO produces reaction: CO 2 +O→CO+O 2 The incidence rate is greater than the second CO production reaction: CO 2 +M→CO+O+M. In other words, by choosing S O / (S O +S CO2 ) ratio makes the gas temperature T in the mixing region m Staying below the thermal limit, the first CO producing reaction occurs at a rate greater than the second CO producing reaction.

[0068] In other embodiments, the method includes setting the gas temperature T in the mixing area MA m Maintain at 1500°K≤T m ≤2500°K temperature range.

[0069] In an embodiment, by controlling the first supply rate S Oand the second supply rate S CO2 The gas temperature T in the mixing zone is controlled so that the ratio between the first and second supply rates is maintained within predefined lower and upper thresholds. m In fact, if Figure 3a and Figure 3b As shown, by explicitly defining S O / (S O +S CO2 ) ratio, can predict the gas temperature.

[0070] Practical implementation of the process of the present invention in terms of equipment and material selection can be facilitated by maintaining the temperature in the mixing zone below an extreme temperature of, for example, 3000°K, and ideally as low as possible while maintaining reasonable conversion. Typically, to maintain reasonable conversion, the temperature should be maintained above 800°K. In addition, if Figure 3a and Figure 3b As shown, steady state conditions are achieved after one millisecond by maintaining the temperature in the mixing zone at, for example, about 2000° K. Steady state conditions also facilitate the removal of the product gas from the mixing zone, since the constant conversion rate provides greater flexibility in the time required to remove the product gas and cool the product gas.

[0071] In an embodiment, the method further comprises establishing a gas temperature T in the mixing area MA m With the first S O and the second S CO2 The relationship between the ratio of the supply rates can be obtained, for example, by model calculation or calibration measurements (including measuring the temperature in the mixing zone as a function of the ratio S O / S CO2 function) to establish this relationship.

[0072] In an embodiment, the method further comprises defining a lower threshold R1 and an upper threshold R2 so that when the control ratio S O / (S O +S CO2 ) to remain within the lower and upper thresholds, a gas temperature within a desired temperature range, for example between 1500°K and 2000°K, is obtained in the mixing region MA.

[0073] As described above, in an embodiment, no external energy source is used to heat the mixing zone and obtain a gas temperature T in the temperature range m .

[0074] Pressure P in the mixing area MA m also plays a role, as this affects the frequency of collisions between atoms and molecules in the mixing region. For embodiments that do not use external heating or cooling means, the pressure P in the mixing regionm The impact of Figure 3d The results show that the 50% atomic oxygen supply and mixing region from 6400 Pa to 10 6 The CO conversion rate at various pressures in the range of Pa. These results show that at about 5 10 4 The best results were obtained at a pressure of 1.4 Pa, with a conversion of about 45%. At lower pressures, such as 6400 Pa, the conversion was very low. Figure 3d At higher pressures, such as 105Pa and 10 6 Pa, CO conversion rate is lower than that at 5 10 4 The best results were obtained at Pa.

[0075] In an embodiment, the method of the present invention comprises adjusting the gas pressure P in the mixing area MA m Keep within the pressure limit so that 10 3 Pa≤P m ≤10 6 Pa, preferably 10 3 Pa≤P m ≤10 5 Pa, more preferably 10 4 Pa≤P m ≤10 5 Pa, P m is the pressure in the mixing area MA.

[0076] The expression "maintaining the gas pressure" means maintaining the pressure in the mixing area MA between the limit values ​​defined above. m The variation is maximum + / - 15%, more preferably maximum + / - 10%, more preferably maximum + / - 5%, more preferably maximum + / - 1%, more preferably maximum + / - 0,1%.

[0077] As mentioned above, Figure 3a As shown, for a specific S O / (S O +S CO2 ) ratio, if the chemical reaction in the mixing zone proceeds long enough before the product gas is discharged from the mixing zone, a steady-state condition, i.e. a constant CO conversion rate, can be obtained. Therefore, in an embodiment, the method of the present invention comprises allowing atomic oxygen and carbon dioxide to interact in the mixing zone MA for a minimum time period longer than 0.1 milliseconds, preferably longer than 0.5 milliseconds, and more preferably longer than 1 millisecond.

[0078] In step 2, atomic oxygen can be generated by various methods known in the art. In an embodiment, atomic oxygen is generated by any of the following atomic oxygen generation methods: generating atomic oxygen using plasma, using thermal energy, using ultraviolet light, or using any other suitable method.

[0079] In an embodiment, atomic oxygen is from O 2 Gas begins to be produced.

[0080] In an embodiment, atomic oxygen is not supplied as pure atomic oxygen, but atomic oxygen may be supplied to the mixing region as a combination of, for example, atomic oxygen and molecular oxygen. Typically, when atomic oxygen is generated using a plasma, both atomic oxygen and molecular oxygen will be present in the plasma and thus will be supplied to the mixing region.

[0081] If both atomic oxygen and molecular oxygen are supplied in the mixing zone, the ratio of atomic oxygen to molecular oxygen has an influence on the CO conversion rate. Figure 4a It is schematically shown in FIG. 1 , where the vertical axis is the O / O2 ratio and the horizontal axis is defined as being equal to S CO2 / (S CO2 +S O +S O2 ) CO2 fraction, and within that, higher and lower maximum conversion ranges can be identified. The higher the O / O2 ratio, the higher the maximum CO conversion, and the smaller the CO2 fraction, the higher the maximum CO conversion. The observation of these bands is directly related to the temperature of the mixing region, and when plotted as a function of the O / O2 ratio and CO2 fraction, the temperature also has a band structure, such as Figure 4b For a given O / O2 ratio, by sufficiently defining the CO2 fraction, an optimal band can be selected, for example a band with a temperature above 1500°K and below 2500°K.

[0082] In embodiments where both atomic oxygen and molecular oxygen are supplied, the method includes maintaining a ratio between the supplied atomic oxygen and the supplied molecular oxygen equal to or greater than a minimum value: S O / S O2 ≥0.10, preferably S O / S O2 ≥0.20, preferably S O / S O2 ≥0.30, S O2 is the third supply rate of molecular oxygen. The third supply rate corresponds to, for example, the number of oxygen molecules supplied to the mixing region per unit time. In other embodiments, the third supply rate may also be expressed in other units.

[0083] As mentioned above, for Figure 3a to Figure 3d , Figure 4a and Figure 4bIn the first set of calculations shown, no external energy was applied to the mixing region to heat or cool the mixing region.

[0084] In alternative embodiments, a heating device or a cooling device may be used to maintain the temperature of the mixing zone at a predefined optimal temperature, such as a temperature of 2000°K, or any other suitable temperature between 1500°K and 2500°K. O / (S O +S CO2 ) ratio, the mixing area needs to be heated or cooled to achieve or maintain the optimum temperature. For example, if S O / (S O +S CO2 ) ratio is relatively low, for example 30%, the maximum temperature that can be reached without heating is about 1500°K. Figure 3b By using a heating device, the temperature can be raised to 2000°K. On the other hand, if S O / (S O +S CO2 ) ratio is relatively high, such as 70%, the maximum temperature is about 3500°K. Figure 3b As shown, by using a cooling device, the temperature can be maintained at a lower temperature, such as 2000 ° K. For example, by cooling the gas mixture, the reverse reaction to produce carbon dioxide is reduced, and at higher S O / (S O +S CO2 ) ratio can also achieve steady-state conditions, resulting in higher carbon monoxide conversion rates.

[0085] Therefore, in an embodiment, the method of the present invention comprises setting the gas temperature T in the mixing area MA to m Maintain at a predefined optimum temperature value with a maximum margin of 15%, preferably a maximum margin of 10%, more preferably a maximum margin of 5%: T m-opt -ER≤T m ≤T m-opt +ER,T m is the gas temperature in the mixing region, T m-opt is a predefined optimum gas temperature value and ER is the margin, and the mixing area MA is heated and / or cooled using heating and / or cooling means to maintain the gas temperature equal to the optimum temperature value within the margin.

[0086] The second set of calculations, performed at a constant temperature of 2000°K, involved calculating the O / (S O +S CO2 ) ratio for heating and cooling, indicating that when Figure 4aWhen plotting the CO2 conversion it shows that the surface area of ​​the low conversion band (i.e. below 20%) is much lower, thus allowing more flexibility in choosing the O / O2 ratio and CO2 fraction to obtain good conversion (e.g. 50% or higher).

[0087] like Figure 2 As schematically shown, in an embodiment, mixing carbon dioxide with atomic oxygen in a mixing area MA includes the following steps: i) generating a first atomic oxygen flow and allowing the first atomic oxygen flow to flow through the mixing area, and ii) generating a second carbon dioxide flow and injecting the second flow into the mixing area so that the first atomic oxygen flow and the second carbon dioxide flow are mixed.

[0088] In embodiments, these atomic oxygen and carbon dioxide flows must be interpreted as gas flows.

[0089] exist Figure 2 In the schematically illustrated embodiment, the first stream of atomic oxygen flows along a first direction, and the second stream of carbon dioxide flows along a second direction, wherein the second direction transversely intersects the first direction.

[0090] Equipment for CO2 conversion

[0091] According to a second aspect of the present invention, there is provided an apparatus for CO conversion. Figure 5 and Figure 6 , shows an example of an embodiment of a device 100 for converting carbon dioxide into carbon monoxide. The device allows the implementation of the method of atomic oxygen driven CO2 conversion as described above.

[0092] The expression "configured for" is non-limiting and can be replaced with "for." The expression is only used to clarify the embodiments and the functions intended to be performed by these features.

[0093] The device 100 for CO2 conversion according to the present disclosure includes an atomic oxygen generator 10 for generating atomic oxygen; a mixing area MA configured to mix the generated atomic oxygen with carbon dioxide to be converted; a carbon dioxide supplier 20 configured to supply the carbon dioxide to be converted to the mixing area; and a control device 30 configured to control a first supply rate S of atomic oxygen. O And control the second supply rate S of carbon dioxide CO2 and a gas outlet 43 configured to discharge a product gas containing carbon monoxide from the mixing zone MA.

[0094] As mentioned above, the first supply rate S O and the second supply rate S CO2The number of oxygen atoms supplied to the mixing area per unit time and the number of carbon dioxide molecules supplied to the mixing area per unit time correspond to each other. By providing a mixing area for mixing atomic oxygen with carbon dioxide, when the device 100 is in operation, the atomic oxygen can interact with carbon dioxide in the mixing area MA through a first reaction: CO 2 +O→CO+O 2 This forms carbon monoxide.

[0095] In an embodiment, the control device 30 is configured to control the atomic oxygen S O The first supply rate and carbon dioxide S CO2 A second supply rate is set such that the ratio between the first supply rate and the sum of the first and second supply rates remains within a lower threshold and an upper threshold: R1 O / (S O +S CO2 ) <R2,S O is the first supply rate of atomic oxygen, S CO2 is the second supply rate of carbon dioxide, and wherein R1 and R2 are the lower threshold and the upper threshold, respectively.

[0096] In an embodiment, the lower threshold R1 and the upper threshold R2 are predefined thresholds.

[0097] As mentioned above, when discussing the method according to the present disclosure, these lower and upper thresholds are also selected for the device so that R1 ≥ 0.1 and R2 ≤ 0.9, preferably R1 ≥ 0.2 and R2 ≤ 0.8, more preferably R1 ≥ 0.3 and R2 ≤ 0.7.

[0098] In an embodiment, if Figure 5 As schematically shown, the control device 30 may, for example, include one or more flow control valves 31, 32 controlled by a controller 33. By controlling the flow control valves, the gas supply rate can be controlled.

[0099] In an embodiment, the device includes a user interface for inputting the values ​​of the lower R1 and upper R2 thresholds. These values ​​may then be stored in the memory of the device. In other embodiments, the values ​​R1 and R2 may be defined by a calibration process, and the resulting values ​​R1 and R2 may be stored in the memory of the device for controlling S O / (S O +S CO2 )ratio.

[0100] In a more advanced embodiment, the control device 30 comprises a controller 33 and a computer program which, when executed by the controller, determines the lower limit R1 and the upper limit R2 thresholds to obtain the desired gas temperature T in the mixing zone. m-req ​Based on the gas temperature T in the mixing area MA m and ratio S O / S CO2 The R1 and R2 thresholds are determined by a predefined mathematical or tabular relationship between . In these embodiments, the apparatus includes a configuration for inputting a desired gas temperature T for the mixing zone. m-req User interface and / or for storing the desired gas temperature T in the mixing area m-req of memory.

[0101] A predefined mathematical or tabular relationship may be defined according to a calibration procedure.

[0102] In an embodiment, the desired gas temperature T is selected m-req For temperature range: 500°K≤T m-req ≤3000°K, preferably 800°K≤T m-req ≤2500°K, more preferably 1000°K≤T m-req ≤2500°K, T m-req is the desired gas temperature in the mixing area MA. Thus, the first CO generating reaction: CO 2 +O→CO+O 2 The occurrence rate of (ΔG°=0.3eV / molecule) is greater than the second CO generation reaction: CO 2 +M→CO+O+M (ΔH°=5.5eV / molecule), ΔG° is the standard enthalpy of the reaction, and M is any neutral molecule.

[0103] In an embodiment, if Figure 5 Schematically shown, the atomic oxygen generator 10 is configured to convert molecular oxygen into atomic oxygen. In these embodiments, the generator 10 includes an oxygen conversion region 12 in which molecular oxygen is converted into atomic oxygen and an oxygen supplier 11 for supplying molecular oxygen to the oxygen conversion region 12.

[0104] In an embodiment, the oxygen supplier 11 receives O2 from a reservoir 15 containing molecular oxygen. For example, the reservoir may be an O2 gas cylinder or tank.

[0105] In an embodiment, the control device 30 is configured to control the third supply rate S of molecular oxygen supplied through the oxygen supplier 11 to O2 To indirectly control the first supply rate S of atomic oxygen o .

[0106] The control device 30 includes, for example, a gas flow control valve 32 for controlling the supply rate of molecular oxygen O2. In fact, the atomic oxygen generator has a specific molecular-atomic oxygen conversion efficiency corresponding to the number of oxygen atoms produced per supplied O2 molecule. Therefore, there is a relationship between the produced atomic oxygen and the supplied molecular O2.

[0107] In an embodiment, the control device 30 is configured to control the first supply rate of atomic oxygen by using a predefined relationship between molecular oxygen supplied to the oxygen conversion zone 12 and atomic oxygen produced in the oxygen conversion zone 12 .

[0108] In an embodiment, a first flow control valve 31 may be used to control the supply of CO2 to the mixing zone, and a second flow control valve 32 may be used to control the supply of molecular oxygen to the atomic oxygen generator 10. The control device may also include a controller 33, which controls the valves and allows, for example, changing the settings of the valves, wherein a change in the valve settings results in a change in the supply rate.

[0109] In an embodiment, the control device 30 is configured to set the gas temperature T in the mixing area MA to m Keep within the following temperature range: 500°K≤T m ≤3000°K, preferably 800°K≤T m ≤2500°K, more preferably 1000°K≤T m ≤2500°K. As mentioned above, the first CO produces the reaction: CO 2 +O→CO+O 2 The incidence rate is greater than the second CO production reaction: CO 2 +M→CO+O+M incidence.

[0110] In other embodiments, the control device 30 is configured to set the gas temperature T in the mixing area MA to m Maintain at 1500°K≤T m ≤2500°K temperature range.

[0111] In an embodiment, the control device 30 is configured to maintain the gas temperature within the temperature range by controlling the ratio between the first supply rate and the second supply rate so that the ratio between the first and second supply rates remains within predefined lower threshold R1 and upper threshold R2 during operation of the device.

[0112] As mentioned above, the pressure P in the mixing area MA m For example, for embodiments in which no external heating or cooling device is used to heat or cool the mixing zone, the pressure limit is, for example, 10 3 Pa≤P m ≤10 6 Pa, preferably 10 3 Pa≤P m ≤10 5 Pa, more preferably 10 4 Pa≤P m ≤10 5 Pa, Pm is the pressure in the mixing area MA. In an embodiment, to keep the pressure within limits, the gas outlet 43 and / or the pump connected to the gas outlet 43 is sized to reduce the gas pressure P in the mixing area (MA) to m Maintain within defined pressure limits.

[0113] The volume of the mixing zone also plays an important role as it determines how long a species remains in the mixing zone before being discharged. Figure 3a and Figure 3b As shown, time plays an important role, for example depending on whether CO is to be discharged when maximum CO conversion is achieved or only after steady-state conditions are reached.

[0114] In an embodiment, the volume of the mixing area MA and the dimensions of the gas outlet 43 and / or the pump are configured to allow atomic oxygen and carbon dioxide molecules to interact in the mixing area within a minimum time period longer than 0.1 milliseconds, preferably longer than 0.5 milliseconds, more preferably longer than 1 millisecond.

[0115] In an embodiment, if Figure 5 Schematically shown, the device 100 according to the present disclosure includes a mixing chamber 40 extending along a longitudinal axis Z, wherein the mixing chamber defines a mixing area MA. The mixing chamber 40 includes: a) an axial inlet 41 configured to receive atomic oxygen produced by the atomic oxygen generator 10, b) one or more inlets 41 configured to supply carbon dioxide to the mixing chamber 40, and c) an outlet for discharging a product gas containing carbon monoxide from the mixing chamber. The outlet of the mixing chamber corresponds to a gas outlet 43 of the device. In an embodiment, the one or more inlets are radial inlets relative to the longitudinal axis.

[0116] The mixing chamber 40 is typically made of a material having a high melting point, and the material may be selected based on the temperature range in which the device operates. The walls of the mixing chamber may be made of or partially made of a high melting point metal such as tungsten, tantalum, or any other suitable metal, for example. In other embodiments, the mixing chamber may be made of, for example, ceramic, glass, or zirconium oxide.

[0117] In an embodiment, if Figure 5 As schematically shown, the atomic oxygen generator 10 is configured to generate an atomic oxygen flow that flows through the mixing area MA in a first direction. Figure 5 In FIG. 1 , the black arrow O indicates that the atomic oxygen flows in a direction parallel to the longitudinal axis Z. The carbon dioxide supplier 20 is configured to inject carbon dioxide into the mixing area MA in a second direction that transversely intersects the first direction. Figure 5 The black arrows CO2 shown in FIG. 2 schematically illustrate a CO2 gas flow perpendicular to the longitudinal axis Z, which is injected into the mixing zone.

[0118] Depending on the purpose of the plant, the carbon dioxide CO2 to be converted can be the result of a capture process or it can be connected to the exhaust gases from which the carbon dioxide CO2 was generated.

[0119] In an embodiment, the carbon dioxide supplier 20 that supplies CO2 to the mixing area is configured to supply CO2 at a gas supply pressure P CO2 and gas temperature T CO2 Carbon dioxide is supplied to the mixing area MA. In an embodiment, 10 3 Pa≤P CO2 ≤10 6 Pa, preferably 10 3 Pa≤P CO2 ≤10 5 Pa, and 200°K≤T CO2 ≤400°K, preferably 250°K≤T CO2 ≤350°K, more preferably 270°K≤T CO2 ≤320°K. In other words, there are no high restrictions or requirements on the pressure and temperature of the carbon dioxide to be converted before injection into the mixing zone. CO2 is set to be greater than the pressure P in the mixing chamber m , so that CO2 is injected into the mixing chamber due to overpressure.

[0120] exist Figure 6 In the illustrated embodiment, the atomic oxygen generator 10 is a plasma generator configured to generate a plasma 101 containing at least atomic oxygen and molecular oxygen, wherein the oxygen conversion region 12 corresponds to a plasma region PL-A for forming the plasma 101 .

[0121] exist Figure 6 In the example shown, the plasma reactor is a microwave reactor including a waveguide 102 to provide the power required to sustain the plasma. In other embodiments, the plasma reactor may be another type of plasma reactor, such as a gliding arc plasma reactor or a glow discharge plasma reactor.

[0122] In an embodiment, wherein the atomic oxygen generator is a plasma reactor, the mixing region MA is located adjacent to the plasma region PL-A and is configured such that when the plasma generator is operating, atomic oxygen flows from the plasma region to the mixing region.

[0123] In an embodiment, the oxygen generated in the plasma region PL-A will flow together with the molecular oxygen toward the mixing region MA, for example, in a direction parallel to the longitudinal axis Z, such as Figure 6 Shown schematically.

[0124] In some embodiments, Figure 6The mixing chamber 40, schematically shown, may be an extension of a plasma chamber confining the plasma. For example, a tubular chamber may be used, wherein a first portion of the chamber forms the plasma chamber and an adjacent second portion forms the mixing chamber.

[0125] In embodiments, the mixing region MA at least partially overlaps with the plasma region PL-A. In these embodiments, the carbon dioxide supplier preferably injects CO2 into the mixing region in the region where the plasma region overlaps with the mixing region. In these embodiments, where the plasma region partially overlaps with the mixing region, the first supply rate of atomic oxygen corresponds to the generation rate of atomic oxygen in the plasma region.

[0126] In an embodiment, the atomic oxygen generator generates atomic oxygen using thermal energy.

[0127] In other embodiments, the atomic oxygen generator generates atomic oxygen using ultraviolet radiation.

[0128] In embodiments, as described above, the mixing area may also be cooled or heated to maintain the temperature of the mixing area at a predefined temperature, for example 2000° K. In these embodiments, the apparatus comprises a heating and / or cooling device configured to heat and / or cool the mixing area MA to maintain the temperature of the gas in the mixing area T m Keep it equal to the optimum temperature value T with a margin m-opt , wherein the maximum margin is 15%, preferably the maximum margin is 10%, and more preferably the maximum margin is 5%, so that: T m-opt -ER≤T m ≤T m-opt +ER,T m is the actual gas temperature in the mixing zone, T m-opt is the predefined optimum gas temperature and ER is the margin.

[0129] In embodiments, the control device 30 is further configured to control the temperature in the mixing region. In these embodiments, the control device 30 includes, for example, a temperature probe configured to measure the temperature in the mixing region. In embodiments, the controller 33 is connected to the heating and / or cooling device and is configured to control the amount of heating and / or cooling generated by the heating and / or cooling device based on the temperature measured in the mixing region.

[0130] In some embodiments, an apparatus (100) for converting carbon dioxide into carbon monoxide comprises:

[0131] an atomic oxygen generator (10) for generating atomic oxygen,

[0132] Mixed Area (MA),

[0133] · Carbon dioxide supply device (20),

[0134] a control device (30), and

[0135] Gas outlet (43).

[0136] In other embodiments, the apparatus (100) for converting carbon dioxide to carbon monoxide comprises:

[0137] an atomic oxygen generator (10) for generating atomic oxygen,

[0138] A mixing area (MA) for mixing the generated atomic oxygen with the carbon dioxide to be converted so that when the device is in operation, the atomic oxygen can interact with the carbon dioxide in the mixing area (MA) to produce a first CO:CO reaction. 2 +O→CO+O 2 Formation of carbon monoxide,

[0139] a carbon dioxide supply (20) for supplying carbon dioxide to be converted to the mixing area (MA),

[0140] A control device (30) for controlling a first supply rate (S) of atomic oxygen supplied to the mixing region O ), and controlling the second supply rate (S) of carbon dioxide supplied to the mixing region CO2 ), such that:

[0141] R1 O / (S O +S CO2 ) <R2

[0142] S O is the first supply rate of the first atomic oxygen, S CO2 is the second supply rate of carbon dioxide, where R1 and R2 are the lower and upper thresholds, respectively, and

[0143] A gas outlet (43) adapted to discharge carbon monoxide from the mixing area (MA).

[0144] Detailed Features

[0145] Hereinafter, the text is provided in the form of clauses. These clauses include characteristic descriptions indicating various options, features, and characteristic combinations that can be used according to the teachings of the present disclosure. Alternative characteristic descriptions of the above may be given, but are consistent with the above description.

[0146] In summary, according to the present disclosure, for example, the following list of clauses may be claimed:

[0147] ​1. A method for converting carbon dioxide into carbon monoxide, the method comprising:

[0148] Provide carbon dioxide to be converted,

[0149] Produce atomic oxygen,

[0150] Mixing carbon dioxide with atomic oxygen in a mixing area (MA) so that the atomic oxygen can interact with the carbon dioxide to produce a first CO:CO reaction 2 +O→CO+O 2 In the mixing area (MA) carbon monoxide is formed,

[0151] • Exhaust carbon monoxide from the mixing area (MA).

[0152] 2. A method for converting carbon dioxide into carbon monoxide, the method comprising:

[0153] Provide carbon dioxide to be converted,

[0154] Produce atomic oxygen,

[0155] · Define the first supply rate of atomic oxygen (S O ) and the second supply rate of carbon dioxide (S CO2 ), such that:

[0156] R1 O / (S O +S CO2 ) <R2

[0157] Among them, S O and S CO2 are the first supply rate and the second supply rate, respectively, and wherein R1 and R2 are a predefined lower threshold and a predefined upper threshold, respectively,

[0158] Mixing carbon dioxide with atomic oxygen in a mixing area (MA) so that the atomic oxygen can interact with the carbon dioxide to produce a first CO:CO reaction 2 +O→CO+O 2 In the mixing area (MA) carbon monoxide is formed,

[0159] and respectively at the first supply rate (S O ) and the second supply rate (S CO2 ) supplies atomic oxygen and carbon dioxide into the mixing area (MA),

[0160] • Exhaust carbon monoxide from the mixing area (MA).

[0161] ​3. The method of clause 1, wherein the first supply rate (S) of atomic oxygen is defined as O ) and the second supply rate of carbon dioxide (S CO2 ), such that:

[0162] R1 O / (S O +S CO2 ) <R2

[0163] Wherein R1 and R2 are a predefined lower threshold and a predefined upper threshold, respectively, wherein R1 ≥ 0.1 and R2 ≤ 0.9, preferably R1 ≥ 0.2 and R2 ≤ 0.8, more preferably R1 ≥ 0.3 and R2 ≤ 0.7.

[0164] 4. The process of clause 2, wherein R1 ≥ 0.1 and R2 ≤ 0.9, preferably R1 ≥ 0.2 and R2 ≤ 0.8, more preferably R1 ≥ 0.3 and R2 ≤ 0.7.

[0165] 5. A method according to clause 2 or clause 4, wherein heat is generated in the mixing area (MA) by the following combined reaction:

[0166] O+O→O 2 And wherein ΔH°=-5.2 eV / molecule, ΔH° is the standard enthalpy of the recombination reaction.

[0167] 6. The method according to clause 5, comprising:

[0168] ·. In the mixing area (MA), a gas temperature (T m ):

[0169] 500°K≤T m ≤3000°K, preferably 800°K≤T m ≤2500°K,

[0170] More preferably 1000°K≤T m ≤2500°K,

[0171] Where T m is the gas temperature (MA) in the mixing area (MA),

[0172] Such that the following first CO producing reaction occurs at a rate of:

[0173] CO 2 +O→CO+O 2 , ΔH°=0.3eV / molecule,

[0174] The incidence of the second CO-producing reaction is greater than:

[0175] CO​2 +M→CO+O+M, ΔH°=5.5eV / molecule,

[0176] ΔH° is the standard enthalpy of the respective CO production reaction, and M is any neutral molecule.

[0177] 7. A method according to clause 6, wherein the gas temperature (T ) in the mixing zone is obtained by controlling the first supply rate and the second supply rate such that the ratio between the first and second supply rates is maintained within a predefined lower and upper threshold. m ).

[0178] 8. A method according to any one of clauses 6 to 7, comprising

[0179] · Establish the gas temperature (T m ) and the ratio S O / (S O +S CO2 ), and

[0180] · Define the lower threshold R1 and the upper threshold R2 so that when the ratio S O / (S O +S CO2 ) is controlled within the lower limit threshold and the upper limit threshold, the gas temperature within the temperature range is obtained in the mixing area (MA).

[0181] 9. A method according to any one of clauses 6 to 8, wherein no external energy source is used to heat the mixing zone and obtain the gas temperature (T m ).

[0182] 10. A method according to any one of clauses 2, 4 or 5, comprising:

[0183] · The gas temperature (T m ) is maintained at a predefined optimal temperature value with a margin, the maximum margin being 15%, preferably the maximum margin being 10%, more preferably the maximum margin being 5%:

[0184] T m-opt -ER≤T m ≤T m-opt +ER,

[0185] T m is the gas temperature in the mixing region, T m-opt is the predefined optimal gas temperature value, ER is the margin,

[0186] and heating and / or cooling the mixing area (MA) using a heating and / or cooling device to reduce the gas temperature (T m ) is maintained equal to the optimum temperature value within this margin.

[0187] 11. The process according to any of the preceding clauses, wherein the carbon dioxide to be converted is in gaseous form at a gas supply temperature T CO2 Supply to the mixing area (MA), where 200°K≤T CO2 ≤400°K, preferably 250°K≤T CO2 ≤350°K, more preferably 270°K≤T CO2 ≤320°K.

[0188] 12. The method according to clause 11, wherein the carbon dioxide to be converted is at a gas supply pressure (P CO2 ) is supplied to a mixing area (MA), wherein

[0189] 10 3 Pa≤P CO2 ≤10 6 Pa, preferably 10 3 Pa≤P CO2 ≤10 5 Pa, P CO2 is the gas supply pressure.

[0190] 13. A method according to any one of the preceding clauses, comprising:

[0191] . The gas pressure (P m ) is kept within the pressure limit so that

[0192] 10 3 Pa≤P m ≤10 6 Pa, preferably 10 3 Pa≤P m ≤10 5 Pa, more preferably 10 4 Pa≤P m ≤10 5 Pa, P m is the pressure in the mixing area (MA).

[0193] 14. A method according to any one of the preceding clauses, comprising:

[0194] . Atomic oxygen and carbon dioxide are allowed to interact in the mixing area (MA) for a minimum time period longer than 0.1 milliseconds, preferably longer than 0.5 milliseconds, more preferably longer than 1 millisecond.

[0195] 15. A method according to any one of the preceding clauses, wherein the atomic oxygen is from O 2 Gas begins to develop.

[0196] 16. A method according to any one of the preceding clauses, wherein the atomic oxygen is supplied to the mixing zone as a combination of atomic oxygen and molecular oxygen.

[0197] 17. The method according to clause 16, comprising:

[0198] Maintaining the ratio between supplied atomic oxygen and supplied molecular oxygen equal to or greater than a minimum value:

[0199] S O / S O2 ≥0.10, preferably S O / S O2 ≥0.20, preferably S O / S O2 ≥0.30, S O2 It is the third supply rate of molecular oxygen.

[0200] 18. The method according to any of the preceding clauses, wherein said mixing of carbon dioxide with atomic oxygen in a mixing area (MA) comprises the following steps:

[0201] i) generating a first stream of atomic oxygen and allowing the first stream to flow through a mixing region, and

[0202] ii) generating a second stream of carbon dioxide and injecting the second stream into the mixing zone so that the first stream of atomic oxygen and the second stream of carbon dioxide are mixed.

[0203] 19. The method of clause 18, wherein the first stream of atomic oxygen flows in a first direction and the second stream of carbon dioxide flows in a second direction, and wherein the second direction is transverse to the first direction.

[0204] 20. A method according to any of the preceding clauses, wherein the atomic oxygen is generated by any of the following atomic oxygen generation methods: using plasma, using thermal energy, using ultraviolet light or using any other suitable method to generate atomic oxygen.

[0205] 21. A method according to any one of the preceding clauses, wherein the first supply rate (S O ) corresponds to the first number of oxygen atoms supplied per unit time, and the second supply rate (S CO2 ) corresponds to a second number of carbon dioxide molecules supplied per unit time.

[0206] 22. The method according to clause 16, wherein the third supply rate (SO2) corresponds to the number of oxygen molecules supplied to the mixing zone per unit time.

[0207] 23. An apparatus (100) for converting carbon dioxide into carbon monoxide, the apparatus comprising:

[0208] an atomic oxygen generator (10) for generating atomic oxygen,

[0209] Mixed Area (MA),

[0210] · Carbon dioxide supply device (20),

[0211] a control device (30), and

[0212] Gas outlet (43).

[0213] 24. An apparatus (100) for converting carbon dioxide into carbon monoxide, the apparatus comprising:

[0214] an atomic oxygen generator (10) for generating atomic oxygen,

[0215] A mixing area (MA) for mixing the generated atomic oxygen with the carbon dioxide to be converted so that when the device is in operation, the atomic oxygen can interact with the carbon dioxide in the mixing area (MA) to produce a first CO:CO reaction. 2 +O→CO+O 2 Formation of carbon monoxide,

[0216] a carbon dioxide supply (20) for supplying carbon dioxide to be converted to the mixing area (MA),

[0217] A control device (30) for controlling a first supply rate (S) of atomic oxygen supplied to the mixing region O ), and controlling the second supply rate (S) of carbon dioxide supplied to the mixing region CO2 ), such that:

[0218] R1 O / (S O +S CO2 ) <R2

[0219] S O is the first supply rate of atomic oxygen, S CO2 is the second supply rate of carbon dioxide, and wherein R1 and R2 are lower and upper thresholds, respectively, and

[0220] • A gas outlet (43) for exhausting carbon monoxide from the mixing area (MA). ​

[0221] 25. An apparatus (100) for converting carbon dioxide into carbon monoxide, the apparatus comprising:

[0222] an atomic oxygen generator (10) for generating atomic oxygen,

[0223] A mixing area (MA) configured to mix the generated atomic oxygen with the carbon dioxide to be converted so that when the device is in operation, the atomic oxygen can interact with the carbon dioxide in the mixing area (MA) to produce a first CO:CO reaction. 2 +O→CO+O 2 Formation of carbon monoxide,

[0224] a carbon dioxide supplier (20) configured to supply carbon dioxide to be converted to the mixing area (MA),

[0225] A control device (30) configured to control a first supply rate (S) of atomic oxygen supplied to the mixing region. O ), and controlling the second supply rate (S) of carbon dioxide supplied to the mixing region CO2 ), such that:

[0226] R1 O / (S O +S CO2 ) <R2

[0227] S O is the first supply rate of atomic oxygen, S CO2 is the second supply rate of carbon dioxide, and wherein R1 and R2 are lower and upper thresholds, respectively, and

[0228] A gas outlet (43) configured for exhausting carbon monoxide from the mixing area (MA).

[0229] 26. The device according to clause 25, comprising

[0230] a user interface configured for inputting the upper and lower threshold values, and / or

[0231] A memory stores the upper and lower threshold values.

[0232] 27. The device according to clause 25 or clause 26, wherein R1 ≥ 0.1 and R2 ≤ 0.9, preferably R1 ≥ 0.2 and R2 ≤ 0.8, more preferably R1 ≥ 0.3 and R2 ≤ 0.7.

[0233] ​28. Apparatus according to clause 25, wherein the control means (30) comprises a controller (33) and a computer program which, when executed by the controller, determines said lower (R1) and upper (R2) thresholds to obtain the desired gas temperature T in said mixing area (MA) m-req , and the determination is based on the gas temperature (T m ) and the ratio S O / S CO2 and wherein the apparatus includes a method for inputting a desired gas temperature (T m-req ) and / or for storing the required gas temperature (T m-req )'s memory.

[0234] 29. The apparatus according to clause 25, wherein the desired gas temperature (T m-req ) in the temperature range:

[0235] 500°K≤T m-req ≤3000°K, preferably 800°K≤T m-req ≤2500°K,

[0236] More preferably 1000°K≤T m-req ≤2500°K,

[0237] T m-re is the desired gas temperature (MA) in the mixing area (MA),

[0238] The incidence rate of the first CO production reaction is:

[0239] CO 2 +O→CO+O 2 , ΔH°=0.3eV / molecule,

[0240] Greater than the incidence of the second CO production reaction:

[0241] CO 2 +M→CO+O+M, ΔH°=5.5eV / molecule,

[0242] ΔG° is the standard enthalpy of the reaction and M is any neutral molecule.

[0243] 30. The device according to any one of clauses 25 to 27, comprising heating and / or cooling means configured to heat and / or cool the mixing area (MA) to reduce the gas temperature (T m ) is kept equal to the optimum temperature value (T m-opt), wherein the margin is a maximum of 15%, preferably a maximum of 10%, more preferably a maximum of 5%, such that:

[0244] T m-opt -ER≤T m ≤T m-opt +ER,

[0245] T m is the gas temperature in the mixing region, T m-opt The predefined optimal gas temperature value, ER is the margin.

[0246] 31. The device according to any one of clauses 25 to 28, wherein the gas outlet (43) and / or the pump connected to the gas outlet (43) is dimensioned to reduce the gas pressure (P m ) is kept within the pressure limit so that

[0247] 10 3 Pa≤P m ≤10 6 Pa, preferably 10 3 Pa≤P m ≤10 5 Pa, more preferably 10 4 Pa≤P m ≤10 5 Pa, P m is the pressure in the mixing area (MA).

[0248] 32. Apparatus according to claim 31, wherein the volume of the mixing area (MA) and the dimensions of the gas outlet (43) and / or the pump are configured to allow atomic oxygen and carbon dioxide molecules to interact in the mixing area within a minimum time period longer than 0.1 milliseconds, preferably longer than 0.5 milliseconds, and more preferably longer than 1 millisecond.

[0249] 33. An apparatus according to any one of clauses 25 to 32, comprising a mixing chamber (40) extending along a longitudinal axis (Z) and wherein the mixing chamber defines the mixing area (MA), and wherein the mixing chamber (40) comprises: a) an axial inlet (41) configured to receive the atomic oxygen produced by the atomic oxygen generator (10), b) one or more inlets (41) configured to supply carbon dioxide to the mixing chamber (40), and c) an outlet for discharging carbon monoxide from the mixing chamber, and wherein the outlet corresponds to the gas outlet (43) of the apparatus.

[0250] 34. An apparatus according to any one of clauses 25 to 33, wherein the atomic oxygen generator (10) is configured to generate a flow of atomic oxygen flowing through a mixing area (MA) along a first direction and wherein the carbon dioxide supplier (20) is configured to inject carbon dioxide into the mixing area (MA) along a second direction transversely intersecting the first direction.

[0251] 35. Apparatus according to any one of clauses 25 to 34, wherein the atomic oxygen generator (10) is configured for converting molecular oxygen into atomic oxygen, and wherein the atomic oxygen generator comprises an oxygen conversion region (12) in which molecular oxygen is converted into atomic oxygen, and an oxygen supplier (11) for supplying molecular oxygen to the oxygen conversion region (12).

[0252] 36. The apparatus according to clause 35, wherein the control device (30) is configured to control the third supply rate (S O2 ) to indirectly control the first supply rate (S O ).

[0253] 37. Apparatus according to clause 35 or clause 36, wherein the control device (30) is configured to control the first supply rate of atomic oxygen by using a predefined relationship between molecular oxygen supplied to the oxygen conversion zone (12) and atomic oxygen produced in the oxygen conversion zone (12).

[0254] 38. Apparatus according to any one of clauses 25 to 37, wherein the atomic oxygen generator (10) is a plasma generator configured to generate a plasma (101) comprising at least atomic oxygen and molecular oxygen, and wherein the oxygen conversion region (12) corresponds to a plasma region (PL-A) for forming the plasma (101).

[0255] 39. Apparatus according to clause 38, wherein the mixing region (MA) is located adjacent to the plasma region (PL-A) and is configured such that when the plasma generator is in operation, atomic oxygen flows from the plasma region to the mixing region.

[0256] 40. Apparatus according to clause 38, wherein said mixing region (MA) at least partially coincides with said plasma region (PL-A).

[0257] 41. The device according to any one of clauses 25 to 40, wherein the carbon dioxide supplier (20) is configured to supply the carbon dioxide at a gas supply pressure (P CO2 ) and gas temperature (T CO2 ) supplies carbon dioxide to a mixing area (MA), and wherein

[0258] 10 3Pa≤P CO2 ≤10 6 Pa, preferably 10 3 Pa≤P CO2 ≤10 5 Pa, P CO2 is the gas supply pressure,

[0259] and 200°K≤T CO2 ≤400°K, preferably 250°K≤T CO2 ≤350°K, more preferably 270°K≤T CO2 ≤320°K, T CO2 is the gas supply temperature.

[0260] 42. The apparatus according to any one of clauses 25 to 41, wherein the first supply rate (S O ) and the second supply rate (S CO2 ) correspond to the number of oxygen atoms supplied to the mixing region per unit time and the number of carbon dioxide molecules supplied to the mixing region per unit time, respectively.

[0261] 43. The apparatus according to clause 36, wherein the third supply rate (S O2 ) corresponds to the number of oxygen molecules supplied to the mixing zone per unit time.

[0262] 44. Apparatus according to any of clauses 25 to 43, wherein the apparatus is adapted to perform a method according to any of clauses 1 to 22.

[0263] Reference numerals

[0264] 10 Atomic oxygen generator 11 O2 Supply 12 O2 conversion area, used to convert O2 into O 15 O2 reservoir 20 Carbon dioxide supply device 30 Controls 31 O2 flow control valve 32 CO2 Flow Control Valve 33 Controller 40 Mixing chamber 41 Gas inlet for supplying CO2 42 Import, for receiving O 43 Gas outlet for exhausting CO 100 equipment 101 plasma 102 waveguide MA Mixed Area PL-A Plasma region <![CDATA[P m ]]> Pressure in the mixing zone <![CDATA[P CO2 ]]> Pressure of supplied CO2 <![CDATA[S O ]]> Supply rate of atomic oxygen <![CDATA[S CO2 ]]> Carbon dioxide supply rate <![CDATA[S O2 ]]> Oxygen supply rate <![CDATA[T m ]]> Temperature in the mixing zone <![CDATA[T CO2 ]]> Temperature of supplied CO2

Claims

1. A method for converting carbon dioxide into carbon monoxide, the method comprising: Provide carbon dioxide to be converted, Produce atomic oxygen, · Define the first supply rate of atomic oxygen (S O ) and the second supply rate of carbon dioxide (S CO2 ), such that: R1<S O / (S O +S CO2 )<R2 Among them, S O and S CO2 are the first supply rate and the second supply rate, respectively, and wherein R1 and R2 are a predefined lower threshold and a predefined upper threshold, respectively, mixing the carbon dioxide with the atomic oxygen in a mixing area (MA) such that the atomic oxygen can interact with the carbon dioxide to form carbon monoxide in the mixing area (MA) via a first CO producing reaction: CO2+O→CO+O2, and respectively at the first supply rate (S O ) and the second supply rate (S CO2 ) supplying the atomic oxygen and carbon dioxide into the mixing area (MA), • Exhaust carbon monoxide from the mixing area (MA).

2. The method of claim 1, wherein R1≥0.1 and R2≤0.9, preferably R1≥0.2 and R2≤0.8, more preferably R1≥0.3 and R2≤0.

7.

3. The method of claim 1 or claim 2, wherein heat is generated in the mixing zone (MA) by the following combined reactions: O+O→O2 and where ΔH°=-5.2eV / molecule, wherein ΔH° is the standard enthalpy of the composite reaction, and wherein the method comprises: ·. In the mixing area (MA), a gas temperature (T m ): 500°K≤T m ≤3000°K, preferably 800°K≤T m ≤2500°K, More preferably 1000°K≤T m ≤2500°K, Where T m is the gas temperature (MA) in the mixing area (MA), Such that the following first CO producing reaction occurs at a rate of: CO2+O→CO+O2, ΔH°=0.3eV / molecule, The incidence of the second CO-producing reaction is greater than: CO2+M→CO+O+M0, ΔH°=5.5eV / molecule, ΔH° is the standard enthalpy of the respective CO production reaction, and M is any neutral molecule.

4. The method of claim 3, wherein the gas temperature (T ) in the mixing zone is obtained by controlling the first supply rate and the second supply rate so that the ratio between the first supply rate and the second supply rate is maintained within a predefined lower threshold and an upper threshold. m ).

5. The method of claim 3 or claim 4, comprising: · Establish the gas temperature (T m ) and the ratio S O / (S O +S CO2 ), and · Define the lower threshold R1 and the upper threshold R2 so that when the ratio S O / (S O +S CO2 ) is controlled within the lower limit threshold and the upper limit threshold, the gas temperature within the temperature range is obtained in the mixing area (MA).

6. The method of claim 1 or claim 2, comprising: · The gas temperature (T m ) is maintained at a predefined optimum temperature value within a maximum margin of 15%, preferably a maximum margin of 10%, more preferably a maximum margin of 5%: T m-opt -ER≤T m ≤T m-opt +IS, Where T m is the gas temperature in the mixing region, T m-opt is the predefined optimal gas temperature value, ER is the margin, and heating and / or cooling the mixing area (MA) using a heating and / or cooling device to reduce the gas temperature (T m ) is maintained equal to the optimum temperature value within the margin.

7. A method as claimed in any one of the preceding claims, comprising: . The gas pressure (P m ) is kept within the pressure limit so that 10 3 Pa≤P m ≤10 6 Pa, preferably 10 3 Pa≤P m ≤10 5 Pa, preferably 10 4 Pa≤P m ≤10 5 Pa, where P m is the pressure in the mixing area (MA).

8. A method as claimed in any one of the preceding claims, comprising: . Atomic oxygen and carbon dioxide are allowed to interact in the mixing area (MA) for a minimum time period longer than 0.1 milliseconds, preferably longer than 0.5 milliseconds, more preferably longer than 1 millisecond.

9. A method as claimed in any one of the preceding claims, wherein the atomic oxygen is supplied to the mixing zone as a combination of atomic oxygen and molecular oxygen, and wherein the method comprises: Maintaining the ratio between supplied atomic oxygen and supplied molecular oxygen equal to or greater than a minimum value: S O / S O2 ≥0.10, preferably S O / S O2 ≥0.20, preferably S O / S O2 ≥0.30, where S O2 It is the third supply rate of molecular oxygen.

10. An apparatus (100) for converting carbon dioxide into carbon monoxide, the apparatus comprising: . an atomic oxygen generator (10) for generating atomic oxygen, a mixing area (MA) configured for mixing the produced atomic oxygen with the carbon dioxide to be converted so that when the device is in operation, the atomic oxygen can interact with the carbon dioxide in the mixing area (MA) to form carbon monoxide through a first CO producing reaction: CO2+O→CO+O2, a carbon dioxide supply (20) configured to supply carbon dioxide to be converted to the mixing area (MA), · A control device (30) configured to control a first supply rate (S) of atomic oxygen supplied to the mixing region O ), and controlling the second supply rate (S) of carbon dioxide supplied to the mixing region CO2 ), such that: R1<S O / (S O +S CO2 )<R2 Among them, S O is the first supply rate of atomic oxygen, S CO2 is the second supply rate of carbon dioxide, and wherein R1 and R2 are lower and upper thresholds, respectively, and A gas outlet (43) configured to discharge carbon monoxide from the mixing area (MA).

11. The device according to claim 10, comprising heating and / or cooling means, which are configured to heat and / or cool the mixing area (MA) to reduce the gas temperature (T m ) is kept equal to the optimum temperature value (T m-opt ), wherein the maximum margin is 15%, preferably the maximum margin is 10%, and more preferably the maximum margin is 5%, so that: T m-opt -ER≤T m ≤T m-opt +IS, Where T m is the gas temperature in the mixing region, T m-opt The predefined optimal gas temperature value, ER is the margin.

12. The device according to claim 10 or claim 11, wherein the gas outlet (43) and / or the pump connected to the gas outlet (43) is dimensioned to reduce the gas pressure (P m ) is kept within the pressure limit so that 10 3 Pa≤P m ≤10 6 Pa, preferably 10 3 Pa≤P m ≤10 5 Pa, preferably 10 4 Pa≤P m ≤10 5 Pa, where P m is the pressure in the mixing area (MA).

13. Apparatus as claimed in claim 12, wherein the volume of the mixing area (MA) and the dimensions of the gas outlet (43) and / or the pump are configured to allow atomic oxygen and carbon dioxide molecules to interact in the mixing area within a minimum time period longer than 0.1 milliseconds, preferably longer than 0.5 milliseconds, more preferably longer than 1 millisecond.

14. The apparatus according to any one of claims 10 to 13, wherein the atomic oxygen generator (10) is configured for converting molecular oxygen into atomic oxygen, and wherein the atomic oxygen generator comprises an oxygen conversion region (12) in which the molecular oxygen is converted into atomic oxygen and an oxygen supplier (11) for supplying molecular oxygen to the oxygen conversion region (12), preferably the control device (30) is configured to control the molecular oxygen supplied by the oxygen supplier (11) by controlling a third supply rate (S O2 ) to indirectly control the first supply rate (S O ).

15. Apparatus according to claim 14, wherein the control means (30) is configured to control the first supply rate of atomic oxygen by using a predefined relationship between molecular oxygen supplied to the oxygen conversion zone (12) and atomic oxygen produced in the oxygen conversion zone (12).

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