KR101560266B1 - Method for producing syngas containing carbon monoxide(co) and hydrogen(h2) - Google Patents

Abstract

The present invention is carbon dioxide (CO ₂₎ from carbon monoxide (CO) and hydrogen as a method for producing synthesis gas comprising (H _2), carbon dioxide (CO ₂₎ the decomposition of carbon dioxide (CO ₂₎ as the flow through the plasma product And then reacting the decomposition products with gaseous hydrocarbons as the decomposition products flow through the hydrocarbon containing gas.

Description

(METHOD FOR PRODUCING SYNGAS CONTAINING CARBON MONOXIDE (CO) AND HYDROGEN (H2)) AND METHOD FOR PRODUCING SYNTHESIS CONTAINING CARBON MONOXIDE (CO) AND HYDROGEN (H2)

The present invention relates to a method of manufacturing a synthesis gas containing carbon monoxide (CO) and hydrogen (H ₂₎ from carbon dioxide (CO _2).

It is known to use carbon dioxide for synthesis gas, i. E. Hydrogen gas mixtures, more particularly for the production of gas mixtures of carbon monoxide and hydrogen or for the production of fuels.

Particularly, when a catalytic production process is used, there arises a problem that the catalyst used does not exhibit a sufficient lifetime. One reason for this is due to thermodynamic phenomena, and another reason is due to the material properties of the catalyst materials used. For example, there is no chemical conversion at reaction temperatures below 400 ° C. Increasing the reaction temperature thermodynamically favored the formation of carbon, which means that there is a risk that the catalyst will be coked, which means that the catalyst is no longer available. This can be prevented by an elevated reaction temperature of over 900 [deg.] C, but sintering of the catalyst material can likewise occur which limits the lifetime of the catalyst.

The use of what is referred to as a so-called plasma-based dielectric barrier discharge has been proposed, in which case it is possible to convert the carbon dioxide-methane mixture to syngas, even at temperatures of 20 to 30 占 폚. However, the problem here is efficiency, because it requires 10 times the energy cost of the reaction enthalpy to obtain a significant conversion.

In addition, recently, it has been proposed to combine a catalyst and a plasma to produce syngas. In this case both conversion and efficiency of syngas increased at reaction temperatures above 700 ° C, but the problem of caulking, that is to say soot formation and limitations of the associated catalyst lifetime, was still not solved.

Thus, the present invention addresses the problem of specifying an improved process for the production of synthesis gas from carbon dioxide.

Such a problem is solved by the present invention for producing a synthesis gas by decomposing carbon dioxide into decomposition products as carbon dioxide flows through the plasma and then reacting the decomposition products with gaseous hydrocarbons as the decomposition products flow through the hydrocarbon gas Lt; RTI ID = 0.0 > of the < / RTI >

In the process according to the invention, a two-step process sequence is taken into account for the production of a synthesis gas, i. E. A gas mixture of carbon monoxide and hydrogen. In the first step, preferably the gaseous carbon dioxide used is generated by a plasma generator The plasma flows through the plasma, which advantageously converts the carbon dioxide completely into the decomposition product, and the gaseous carbon dioxide used can be in pure form or part of a gas mixture. Here, the temperature reaches several thousand degrees Celsius.

In the second step, the decomposition products are supplied to the hydrocarbon gas or mixed with the gaseous hydrocarbons as they flow through the hydrocarbon gas. Examples of the decomposition products include elemental carbon and oxygen, carbon or oxygen radicals as well as various Molecular fragments. Here, it is preferable to use pure gaseous hydrocarbons. Due to the high temperature of the gaseous cracking products, an endothermic reaction occurs with the hydrocarbons providing synthesis gas during mixing. The mixing time is relatively short, which means that mixing preferably occurs within a few milliseconds (ms).

Thus, the present invention proposes a thermodynamically preferred process path for the production of syngas resulting in rapid efficient chemical conversion. Due to the high mixing and reaction rates of the hydrocarbons and carbon dioxide decomposition products, heating of the gas mixture of hydrocarbon and carbon dioxide typically used, which soot formation will pass through as expected in the thermodynamically favored temperature range, is prevented.

Preferably, the carbon dioxide and / or decomposition products flow at a flow rate of 10 to 100 m / s. Such a high flow rate first shortens the residence time of the carbon dioxide in the plasma, so that the thermodynamic equilibrium of the decomposition reaction (s) of the carbon dioxide can not be established. Thus, the electrical energy of the plasma is used at a higher rate for the decomposition of the carbon dioxide molecules, and a high mixing rate of gaseous hydrocarbons and decomposition products is achieved in the second process step. In this way, the yield of synthesis gas, and thus the efficiency of the process according to the invention, can be increased overall, and the desired carbon monoxide and hydrogen product can be obtained with high selectivity. In exceptional cases, the flow rate may also be higher or lower.

In the present invention, the plasma may be generated using a plasma generator that provides a magnitude of the converted field strength in the working gas range from about 100 V / mm bar to about 10 kV / mm bar. Correspondingly, the converted electric field produces high-energy electrons in the plasma, which accelerates or accelerates decomposition of the carbon dioxide. The plasma is preferably not completely thermalized. That is, they are not in thermodynamic equilibrium. At atmospheric pressure and an operating voltage of 10 kV, this means that the electrodes used for plasma generation can be separated from 1 mm to 100 mm. At higher pressures, higher operating voltages or fewer electrode separations are required. Plasma generation is of course not limited to these ranges of configuration parameters and operating conditions. More particularly, it is also possible to operate the plasma at a converted field strength of less than 100 V / mm bar, in which case lower efficiency is expected for carbon dioxide decomposition, but on the other hand, the gas flow and / More fluid operation is possible for the electricity supply.

Advantageously, the decomposition product is mixed with the hydrocarbon gas in such a way that the temperature of the synthesis gas produced is 1100 ° C or less, in particular 700 to 1000 ° C. Accordingly, after the end of the process, the temperature of the synthesis gas is about 1000 캜 or lower. This process should advantageously be carried out in such a way that these criteria are met, and likewise an important reason for this is the thermodynamically favored equilibrium condition.

Plasma generation can be accomplished using an electrode that is in direct contact with the flowing carbon dioxide, and a direct current, alternating current, especially a low frequency alternating current, or a pulse-periodic current. The use of pulse-period currents has the advantage that thermal neutronization, i.e. the establishment of thermodynamic equilibrium, is suppressed, but for this purpose an increase in the cost of supplying electrical energy is inevitable. In the case of direct current plasma or low frequency alternating plasma, the electrode may be in direct contact with the plasma, in which case a graphite electrode is preferably used.

Alternatively, the generation of the plasma may be accomplished using electrodes that are not in direct contact with the flowing carbon dioxide, and pulse-period currents, particularly high frequency pulse-period currents, alternating currents, especially high frequency alternating currents, or electromagnetic waves, especially microwaves . In the case of using microwave or high-frequency AC in the radio frequency range, it is possible to prevent direct contact between the plasma and the electrode accordingly, and no protective gas is required. The use of surface wave plasmas at particularly high flow rates of carbon dioxide or decomposition products or mixtures of hydrocarbon gases is preferred.

Particularly advantageously, the waste heat generated in the process is fed to a device for generating steam, in particular to a heat exchanger for steam generation. Therefore, the heat energy generated in the process can be technically used, and in this case, the generated steam, more particularly, the generated steam, is more preferably supplied to the decomposition products of carbon dioxide and / or the hydrocarbon gas. In this way, undesirable soot formation in the cooling process of the syngas can be thermodynamically suppressed, and the chemical equilibrium of the product can be shifted toward hydrogen.

The syngas can be fed to the catalyst for subsequent reactions, in particular to a catalyst based on nickel (Ni) or zirconium (Zr). In this way, the material that has not been completely converted during the production process is given the possibility of reaction by a catalytic support to provide a syngas. The catalyst may be present, for example, as a solid form, for example, as a solid form of a honeycomb structure, or in powder form. It is also possible to use other catalyst materials as well as the above-mentioned nickel or zirconium catalysts.

Advantageously, it is possible to supply the synthesis gas to the synthesis reaction, in particular to the methanol or dimethyl ether synthesis. In this variant of the invention, the thermal energy of the produced syngas is used for the downstream process; Accordingly, process heat is efficiently used. In subsequent dimethyl ether synthesis it is possible to improve the conventional catalytic production process which consists essentially of removing water from methanol to provide dimethyl ether, because typically the use of the required hydrogen is reduced. Likewise, the efficiency of the dimethyl ether synthesis can be increased.

The present invention also relates to an apparatus for producing a synthesis gas comprising carbon monoxide and hydrogen from carbon dioxide, which is configured to perform the process described above. Such a device comprises at least one first reaction chamber and at least one second reaction chamber, wherein the first reaction chamber comprises at least one plasma generating device for the decomposition of carbon dioxide, wherein at least one Feed through a feed line, through which carbon dioxide flows into the decomposition product; The second reaction chamber is connected downstream of the first reaction chamber through one or more lines or directly connected to the first reaction chamber, and the hydrocarbon gas supplied through the supply line to the second reaction chamber is contained or supplied to the hydrocarbon Gas is flowing; The synthesis gas is produced as the decomposition product reacts with the gaseous hydrocarbons in the process of the decomposition products flowing through the gaseous hydrocarbons, and is discharged through the outlet line. Accordingly, the two-step production process of the present invention for producing syngas with the apparatus of the present invention is characterized in that the supplied carbon dioxide is decomposed by the plasma generated therein in the reaction chamber or the first reaction chamber (s) So that subsequent mixing of the decomposition products of the hydrocarbon gas with carbon dioxide in the chamber or the second reaction chamber (s) can be achieved. All reaction chambers are equipped with suitable inlet and outlet lines so that gaseous materials used in the production process according to the invention can flow between them. Likewise, it is possible for one or more second reaction chamber (s) to be connected directly to one or more first reaction chamber (s), or to make direct contact therebetween. The apparatus of the present invention is also particularly capable of having two or more individual device units for the production of syngas connected in parallel, each of which may be an individual or grouped one or more 1 and at least one second reaction chamber.

Preferably, the plasma generator has a plurality of plasma sources. This results in improved mixing of gaseous hydrocarbons and decomposition products, a particular reason for this is that the use of several small plasma sources for the decomposition of carbon dioxide provides a greater ratio of contact area to space. As mentioned above, the plasma source may have different electrical excitation. The converted field strength of the plasma source is preferably in the range of about 100 V / mm bar to about 10 kV / mm bar.

Advantageously, the at least one line between the first reaction chambers and the second reaction chambers and / or the second reaction chamber has one or more orifices for the introduction of steam, in particular steam. As described for the process according to the present invention, feeding a small amount of steam thermodynamically suppresses soot formation during the cooling of syngas, and can also predominantly transfer the product spectrum to hydrogen.

For the subsequent reaction of the synthesis gas, there may be a catalyst downstream of the second reaction chamber, in particular a catalyst based on nickel (Ni) or zirconium (Zr). Accordingly, it is possible to catalytically convert the incompletely converted material or compound into syngas, which increases the efficiency of syngas production.

Further, there may be additional reaction chambers for performing synthesis reactions, particularly methanol or dimethyl ether synthesis, downstream of any catalyst or second reaction chamber connected downstream of the second reaction chamber. In this way, the thermal energy of the syngas can be efficiently used for the downstream process.

Further advantages, features and details of the present invention are evidenced from the working examples described below and from the drawings.

Figure 1 shows an apparatus for carrying out the process according to the invention according to a first embodiment.
Figure 2 shows an apparatus for carrying out the process according to the invention according to a second embodiment.
Figure 3 shows an apparatus for carrying out the process according to the invention according to a third embodiment.
4 shows an apparatus for carrying out the process according to the invention according to a fourth embodiment.
Figure 5 shows an apparatus for carrying out the process according to the invention in accordance with a fifth embodiment.
Figure 6 shows an apparatus for carrying out the process according to the invention according to a sixth embodiment.
Figure 7 shows a part of an apparatus for carrying out the process according to the invention according to a seventh embodiment.
Figure 8 shows an apparatus for carrying out the process according to the invention according to an eighth embodiment.

Figure 1 shows an apparatus 1 for carrying out the process according to the invention to produce a synthesis gas containing carbon monoxide (CO) and hydrogen (H ₂₎ from carbon dioxide (CO ₂₎ according to the first embodiment . The apparatus 1 basically comprises first and second reaction chambers 2 and 3, which are connected to one another via a line 4. Dedicated inlet lines 5 and 6 are arranged in the reaction chambers 2 and 3 and a discharge line 7 is arranged in the second reaction chamber 3.

The first reaction chamber 2 advantageously comprises at least one plasma generating device 8 having several plasma sources 8 ', as shown in FIG. The plasma generator 8 and the plasma source 8 'are connected to the electrical energy supply 16 by an electrical energy supply line 17.

The first reaction chamber 2 serves to decompose the carbon dioxide which is supplied through the inlet line 5 and flows through the first reaction chamber 2 at a flow rate of, for example, about 50 m / s It flows into the decomposition product. This is done at a temperature of several thousand degrees Celsius. The plasma generator 8 is operated, for example, with a converted field strength of 1 kV / mm bar, which ensures that the generated plasma is not completely thermally neutralized, i.e. not in thermodynamic equilibrium. In order to generate the plasma, it is preferable to use a high-frequency alternating current in the radio frequency range, because in this method, the contact of the plasma with the electrode of the plasma generating device 8 is unnecessary and the use of the protective gas is not necessary . It is also advantageous to use a surface wave plasma for the desired high flow rate. More particularly, the plasma power is concentrated in a small space where carbon dioxide flows at the above-mentioned high flow rate. Thus, the residence time in the electrical energy dissipation zone is short enough to inhibit the establishment of thermodynamic equilibrium, and a high proportion of electrical energy is used to decompose the carbon dioxide.

The decomposition products are mixed with the gaseous hydrocarbons fed via line 6 in accordance with the flow to the second reaction chamber 3 via line 4 and then converted to synthesis gas and passed through line 7 to about And is discharged from the second reaction chamber 3 as a final product at a temperature of 800 to 900 ° C. Here again, it is advantageous that both the cracked product and the gaseous hydrocarbons have a high flow rate, because of this, a high mixing rate is caused thereby. The mixing time is, for example, only a few milliseconds (ms). In the line 4, the plasma gas containing the decomposition product of carbon dioxide is allowed to pass through the reaction chamber 3 in a short time in order to prevent undesired heat loss and subsequent reactions. This can also be completely omitted so that the plasma generator 8, that is, the reaction chamber 2 of the plasma reactor, is in direct contact with the reaction chamber 3.

Advantageously, as shown in Figure 2, a suitable plasma generator 8 or several first reaction chambers 2 having a plasma reactor are arranged in the second reaction chamber 3 for reforming . Whereby a large contact area required between the plasma gas and the hydrocarbons is achieved.

The process according to the invention consists of a thermodynamically favorable process path leading to a rapid and efficient chemical conversion of the materials used in the synthesis gas. At the same time, basically dividing the process into two steps prevents the gas mixture of carbon dioxide and hydrocarbon from being heated, thereby avoiding the thermodynamically favorable temperature range for soot formation. The reaction chambers 2 and 3 and the energy supply unit 16 or the electric power supply unit required for the operation of the plasma generator 8 and the plasma source 8 'are small and inexpensive.

Figure 3 shows an apparatus 1 for carrying out the process according to the invention in accordance with a third embodiment. 1 or 2 is that steam is supplied from the heat exchanger 10 to the second reaction chamber 3 via an additional feed line 9, and as a result of this, Is thermodynamically suppressed during the cooling of the gas, and the product spectrum of the produced syngas is predominantly transferred to hydrogen. The heat exchanger 10 can advantageously be operated using the process heat generated in the process according to the invention.

4 shows a variant in which steam does not exit directly into the second reaction chamber 3 but rather goes to the line 4 connecting the two reaction chambers 2,3 to premix the decomposition products with the steam will be.

Figure 5 shows an apparatus 1 for carrying out the process according to the invention in accordance with a fifth embodiment. Here, the catalyst 11 connected downstream of the second reaction chamber 3 serves to subsequently react the incompletely converted material and thereby achieve complete conversion of the material used. The catalyst 11 can be composed of, for example, a solid-state catalyst based on a perovskite structure with zirconium as the active element.

Fig. 6 is a graph showing the results of the downstream process occurring in the reaction chamber 12 connected to the downstream of the catalyst 11 after passing through the catalyst 11, that is, for example, Or an option to supply syngas to the dimethyl ether synthesis. For this purpose, the catalyst 11 is connected to the reaction chamber 12 via line 13. Here, it may be possible to supply hydrogen from the reservoir 14 to the reaction chamber 12 via line 15 to establish the desired carbon monoxide to hydrogen ratio in the synthesis gas. Hydrogen can be obtained, for example, through an electrolysis process. Overall, there is thus the advantage that the thermal energy obtained in the process according to the invention can be efficiently used for methanol synthesis. The same applies when the direct dimethyl ether synthesis takes place in the reaction chamber 12, since, in particular, compared to the two-step catalytic process for the dimethyl ether synthesis known from the prior art, The process heat here likewise increases the efficiency of the reaction.

Figure 8 shows a further option for scaling the process according to the invention. Instead of arranging a plurality of first reaction chambers 2 for plasma decomposition of carbon dioxide in a large second reaction chamber 3 for reforming, the apparatus 1, 1 'of the present invention is parallel to several units , Wherein the apparatus (1, 1 ') consists of a first and a second reaction chamber (2, 3), respectively, and optionally a catalyst (11) or catalytic reactor. This ensures that the contact area between the plasma gas containing the decomposition product of carbon dioxide and the hydrocarbon grows to a plant size.

Claims (26)

Carbon dioxide as a method for producing synthesis gas from (CO ₂₎ include carbon monoxide (CO) and hydrogen (H _2), carbon dioxide (CO ₂₎ is as the flow through the plasma by decomposing carbon dioxide (CO ₂₎ as a degradation product And then producing the synthesis gas by reacting the decomposition products with the gaseous hydrocarbons as the decomposition products flow through the hydrocarbon gas,
Wherein the carbon dioxide (CO ₂ ) and / or decomposition products flow at a flow rate of 10 to 100 m / s and the plasma is generated using a plasma generator at a converted electric field intensity in the range of 100 V / mm bar to 10 kV / mm bar And the decomposition product is mixed with the hydrocarbon gas in such a way that the temperature of the produced synthesis gas is 1100 ° C or less. The process according to claim 1, characterized in that the decomposition product is mixed with the hydrocarbon gas in such a manner that the temperature of the produced synthesis gas is from 700 to 1000 ° C. 3. The method of claim 1 or 2, wherein the plasma generation is accomplished using an electrode in direct contact with the flowing carbon dioxide and a direct current, alternating current, or pulse-periodic current. 4. The method of claim 3, wherein the alternating current is low frequency alternating current. 4. The method of claim 3, wherein plasma generation is achieved using a graphite electrode. 3. The method of claim 1 or 2, wherein the plasma generation is accomplished using an electrode that is not in direct contact with the flowing carbon dioxide, and a pulse-period current, alternating current, or electromagnetic wave. 7. The method of claim 6, wherein the pulse-period current is a high-frequency pulse-period current. 7. The method of claim 6, wherein the alternating current is a high frequency alternating current. 7. The method of claim 6, wherein the electromagnetic wave is a microwave. 3. The method according to claim 1 or 2, wherein the plasma used is a nonthermalized plasma. The method according to claim 1 or 2, wherein the waste heat generated in the process is supplied to an apparatus for generating steam. 12. The method of claim 11, wherein the apparatus for generating steam is a heat exchanger for generating steam. 3. A process according to claim 1 or 2, characterized in that vapor is supplied to the decomposition products of carbon dioxide and / or steam is supplied to the hydrocarbon gas. 14. The method of claim 13, wherein the steam is steam. 3. Process according to claim 1 or 2, characterized in that the synthesis gas is fed to the catalyst for subsequent reaction. 16. The process according to claim 15, wherein the catalyst is a catalyst based on nickel (Ni) or zirconium (Zr). 3. A process according to claim 1 or 2, characterized in that synthesis gas is fed to the synthesis reaction. 18. The process of claim 17, wherein the synthesis reaction is methanol or dimethyl ether synthesis. Claim 1 or configured to perform a 2 of the process, carbon dioxide as an apparatus for producing synthesis gas comprising carbon monoxide (CO) and hydrogen (H ₂₎ from (CO _2), the device (1) has at least one first comprising: a reaction chamber (2) and at least one second reaction chamber 3, and the first reaction chamber comprises at least one plasma generating device (8) for the decomposition of carbon dioxide (CO _2), this first reaction Carbon dioxide is supplied to the chamber 2 through one or more supply lines through which carbon dioxide flows into the decomposition products; The second reaction chamber 3 is connected to the downstream side of the first reaction chamber 2 via one or more lines 4 or directly connected to the first reaction chamber 2, The hydrocarbonaceous gas fed through the feed line 5 is contained or flows therethrough; The synthesis gas is produced as the decomposition products react with the gaseous hydrocarbons in the course of the decomposition products flowing through the gaseous hydrocarbons, is discharged through the outlet line 7,
(CO ₂ ) and / or decomposition products flow at a flow rate of 10 to 100 m / s and the plasma is generated in the plasma generator 8 at a converted electric field intensity in the range of 100 V / mm bar to 10 kV / mm bar And the decomposition product is mixed with the hydrocarbon gas in such a manner that the temperature of the produced synthesis gas is 1100 ° C or less. 20. Apparatus according to claim 19, characterized in that the plasma generating device (8) has a plurality of plasma sources (8 '). 20. Apparatus according to claim 19, characterized in that the at least one line (4) and / or the second reaction chamber (3) have at least one orifice for the introduction of steam. 23. The apparatus of claim 21, wherein the steam is steam. Process according to claim 19, characterized in that the catalyst (11) is connected downstream of the second reaction chamber (3) for the subsequent reaction of the synthesis gas. 24. The apparatus according to claim 23, wherein the catalyst (11) is a catalyst based on nickel (Ni) or zirconium (Zr). 20. An apparatus according to claim 19, characterized in that an additional reaction chamber (12) for carrying out the synthesis reaction is connected downstream of the catalyst (11) or the second reaction chamber (3). 26. The apparatus of claim 25, wherein the synthesis reaction is methanol or dimethyl ether synthesis.

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