Synthesis method and synthesis device for liquid hydrocarbon

Abstract

To provide a method and a device for efficiently producing liquid hydrocarbon from oxygen and carbon dioxide in water.SOLUTION: There are provided a synthesis method and a synthesis device for liquid hydrocarbon HC which are a method and a device where, in a reaction vessel 1 accommodating water W having carbon dioxide dissolved therein and being in a state of being mixed with the liquid hydrocarbon HC, the carbon dioxide and the water W are reduced into carbon monooxide and hydrogen via a photocatalyst and also the liquid hydrocarbon HC is additionally synthesized by chemical reaction between the carbon monooxide and the hydrogen via the photocatalyst. In the method and the device, supply of mixed gas M having carbon dioxide and air A from the bottom part and / or a trunk part of the reaction vessel 1 or supply of the carbon dioxide and the air A from the bottom part and / or a side part of the reaction vessel 1, respectively, causes contact with bubbles of the mixed gas M passing through a layer of the liquid hydrocarbon HC synthesized in a region above the water W and contact between an upper interface of the layer and the mixed gas M having the carbon dioxide and the air A.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention is directed to a method and apparatus for reducing carbon dioxide and water to carbon monoxide and hydrogen in water via a photocatalyst, and synthesizing liquid hydrocarbons by a chemical reaction of the carbon monoxide and the hydrogen via the photocatalyst. [Background technology]

[0002] The synthesis of liquid hydrocarbons by reducing carbon dioxide in water has already been proposed in the prior art.

[0003] For example, Patent Document 1 proposes a method of producing liquid hydrocarbons by supplying oxygen to water containing carbon dioxide in a photoelectrochemical cell and reducing the carbon dioxide (page 81, lines 4-21).

[0004] That is, the photocatalyst in Patent Document 1 is premised on a photoelectrochemical cell, and on the premise that fuel is produced from liquid hydrocarbons or the like at the cathode (Claims 2, 77, 79).

[0005] Therefore, in Patent Document 1, reduction of carbon dioxide and water by pure photocatalysis is not realized. In fact, in Patent Document 1, activation of oxygen by irradiating water with ultraviolet light is not achieved (in this respect, it is clearly different from Patent Document 2).

[0006] As shown in Patent Document 2, the inventors of the present application have proposed a method and apparatus for producing liquid hydrocarbons, which is premised on supplying oxygen to water containing dissolved carbon dioxide and generating oxygen nanobubbles, and reducing the carbon dioxide and water to carbon monoxide and hydrogen via a photocatalyst in the presence of active oxygen generated from the nanobubbles by irradiation with ultraviolet light.

[0007] However, in the case of Patent Document 2, the configuration is not necessarily simple in that it requires the generation of oxygen nanobubbles and the generation of active oxygen by irradiation with ultraviolet rays.

[0008] In Patent Documents 1 and 2, when liquid hydrocarbons are produced via a photocatalyst, a layer of liquid hydrocarbons is produced in an upper region above water.

[0009] In such a case, contact with the air above containing carbon dioxide is realized, and in this case, the reduction efficiency of carbon dioxide in the water depends on the concentration of carbon dioxide gas contained in the air.

[0010] However, in the conventional techniques such as those disclosed in Patent Documents 1 and 2, the basic idea of ​​efficiently producing liquid hydrocarbons by adjusting the concentration of carbon dioxide gas in the air that comes into contact with the upper interface where liquid hydrocarbons are present is not proposed at all. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] WO2010 / 042196 A1 [Patent Document 2] Patent No. 6440742 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention aims to provide a method and apparatus for highly efficient production of liquid hydrocarbons via photocatalysis of water having dissolved therein oxygen and carbon dioxide. [Means for solving the problem]

[0013] In order to solve the above problems, the basic configuration of the present invention is as follows: (1) A method for reducing carbon dioxide and water to carbon monoxide and hydrogen through a photocatalyst in a reaction vessel containing water in which carbon dioxide is dissolved and mixed with liquid hydrocarbons, and further synthesizing the liquid hydrocarbons through a chemical reaction between the carbon monoxide and the hydrogen through the photocatalyst, comprising the steps of: Reactor or by supplying bubbles of the carbon dioxide and air mixture into the bottom and / or sides of the Carbon dioxide bubbles and A method for synthesizing liquid hydrocarbons, comprising: supplying air bubbles to maintain an upper interface of a layer of liquid hydrocarbons produced in an upper region of a reaction vessel in contact with a mixed gas of carbon dioxide and air which has passed through said layer; (2) In a reaction vessel containing water mixed with liquid hydrocarbons, the reaction vessel is heated through a photocatalyst. Bottom and / or sides of The apparatus reduces carbon dioxide continuously supplied from the reactor to carbon monoxide and hydrogen in water, and synthesizes liquid hydrocarbons in a layered form in the upper region of the reaction vessel by a chemical reaction between the carbon monoxide and the hydrogen via the photocatalyst. The photocatalyst is contained in photocatalytic means and A source of the carbon dioxide and air mixture at the bottom and / or side of the reactor. Connect to or A carbon dioxide source and a gas source are provided at the bottom and side of the reactor, respectively. a liquid hydrocarbon synthesis unit connected to a source of air; It consists of: Effect of the Invention

[0014] By the method of the basic configuration (1) and the apparatus of the basic configuration (2), in the layer of liquid hydrocarbons produced in the region above water in the reaction tank, the layer is brought into contact with the passing mixed gas of carbon dioxide and air, and a contact state with the mixed gas of carbon dioxide and air at the upper interface of the layer is maintained, thereby making it possible to realize extremely efficient reduction of carbon dioxide and further synthesis of liquid hydrocarbons. That is, the efficient synthesis is made possible by both the stage in which the bubbles of the mixed gas pass through the layer while contacting the entire surfaces of the bubbles, and the stage in which the contact state is maintained at the upper interface. In particular, the effect of the former stage becomes more remarkable as the synthesis of liquid hydrocarbons progresses and the layer in the upper region becomes larger. In the basic configurations (1) and (2), it is assumed that carbon dioxide is continuously supplied. However, when a mixture of carbon dioxide and air is supplied, the above-mentioned effects are naturally produced. Even if the gas mixture is not Even if the temperature is not high, when carbon dioxide bubbles and air bubbles are supplied from the bottom and side of the reaction vessel, respectively, By the time the bubbles pass through the layer, they have produced a significant proportion of a mixture of carbon dioxide and air, thereby achieving the above effect.

[0015] The method of basic configuration (1) and the device of basic configuration (2) are extremely simple compared to the configuration employing electrodes in Patent Document 1, and furthermore, they do not require the application of voltage, and can obtain liquid hydrocarbons as fuel purely through a photocatalytic reaction.

[0016] In the case of the method of basic configuration (1) and the device of basic configuration (2), a mixed gas of carbon dioxide and air or air is supplied, and the air contains oxygen. Therefore, unlike Patent Document 2, the supply of oxygen and the formation of nanobubbles of the oxygen are not essential, and a simple configuration is realized.

[0017] In this way, the present invention, which is based on the method of the basic configuration (1) and the apparatus of the basic configuration (2), can realize extremely efficient production of liquid hydrocarbons, despite its simple configuration. Incidentally, the configuration of Patent Document 2 also includes a configuration in which carbon dioxide is reduced in the presence of active oxygen generated from separately prepared liquid hydrocarbons and oxygen nanobubbles. When such a mixed state is left in place for, for example, 24 hours, the proportion of liquid hydrocarbons further synthesized is usually 10 to 15% (paragraph

[0029] ). In contrast, in the basic configuration (1), when the carbon dioxide concentration of the air in contact with the liquid hydrocarbons is adjusted to within the range of 430 ppm to 2000 ppm, the proportion of liquid hydrocarbons further synthesized can be made 20 to 30%. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a block diagram showing the method of the basic configuration (1). [Diagram 2] FIG. 1 is a schematic diagram showing the configuration of an apparatus of basic configuration (2), in which (a) shows an embodiment in which a supply source of a mixed gas of carbon dioxide and air is used and the amount of air to be mixed is adjusted, and (b) shows an embodiment in which an air supply source is used, air is supplied above the reaction tank, and the supply amount is adjusted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The basic configuration (1) is a method for reducing carbon dioxide and water to carbon monoxide and hydrogen through a photocatalyst in a reaction vessel 1 that contains W in which carbon dioxide, which is continuously supplied, is dissolved and mixed with liquid hydrocarbons (HC), as shown in the block diagram of FIG. 1, and further synthesizing the liquid hydrocarbons (HC) through a chemical reaction between the carbon monoxide and the hydrogen through the photocatalyst, Reactor or supplying bubbles of the mixture gas M of carbon dioxide and air A from the bottom and / or sides of the Carbon dioxide bubbles and This is a method for synthesizing liquid hydrocarbons (HC), in which air A bubbles are supplied so that the upper interface of a layer of liquid hydrocarbons (HC) produced in the upper region of the reaction vessel (1) is kept in contact with a mixed gas M of carbon dioxide and air A which has passed through the layer.

[0020] As shown in the schematic diagram of FIG. 2, the device of the basic configuration (2) is a reactor 1 that contains water W in a mixed state with liquid hydrocarbons HC. The reactor 1 Bottom and / or sides of The carbon dioxide continuously supplied from the reactor is reduced to carbon monoxide and hydrogen in water, and the carbon monoxide and the hydrogen react with each other via the photocatalyst to synthesize liquid hydrocarbons (HC) in a layered manner in the upper region of the reactor (1). The photocatalyst is contained in photocatalytic means and A supply source 2 of the mixed gas M of carbon dioxide and air A at the bottom and / or side of the reaction vessel 1 Connect to or At the bottom and side of the reactor 1, a carbon dioxide source 3 and Air A source 4 This is a liquid hydrocarbon synthesis device connected to the

[0021] In the basic configurations (1) and (2), bubbles of a mixed gas M of carbon dioxide and air A are supplied, Carbon dioxide bubbles and air A bubbles are introduced into the bottom and side of the reaction vessel 1, respectively. Although both the case where the liquid hydrocarbons are supplied from the source and the case where the liquid hydrocarbons are supplied from the source are included, the former is usually adopted in many cases, taking into consideration efficient synthesis of liquid hydrocarbons (HC).

[0022] In the basic configurations (1) and (2), the continuous supply of carbon dioxide for the production of liquid hydrocarbons HC is a technical premise. As already pointed out in the section on effects, however, the following technical points can be inferred as the basis for the promotion of the reduction reaction by contact between the layer of liquid hydrocarbons HC in the upper region and the mixed gas M of carbon dioxide and air A passing through the layer, and further by contact between the upper interface of the water W in which liquid hydrocarbons HC are produced and the mixed gas M of carbon dioxide and air A.

[0023] When carbon dioxide dissolved in water is photocatalyst-treated to form radical water, that is, activated water that is prone to chemical reactions, the following reduction reactions caused by the radicalization proceed sequentially. CO 2 +H 2 O→CO+H 2 +O 2 (1) That is, in the above formula (1), the reduction reaction proceeds sequentially from left to right. When focusing on each individual reaction, there is a reverse reaction in which carbon monoxide molecules are oxidized to carbon dioxide molecules, but overall, the reaction proceeds in which carbon dioxide molecules are sequentially reduced to carbon monoxide molecules.

[0024] Following the reaction formula (1) above, in the radical water, the following reaction formula proceeds, which further produces liquid hydrocarbons HC due to the radicalization: (2n+1)H 2 +nCO→C n H 2n+2 +nH 2 O (2) Therefore, C generated in the upper region of the water W n H 2n+2 The liquid hydrocarbon layer formed by the above process is derived from reaction (2). Incidentally, the carbon number n is the same as the carbon number of the liquid hydrocarbons HC that are blended in advance and are in a mixed state with the radical water, and therefore the liquid hydrocarbons HC that are blended in advance are called the mold. However, the reason why the carbon number n of the further synthesized liquid hydrocarbons HC is the same as the carbon number of the template liquid hydrocarbons HC has not been fully elucidated.

[0025] In the case of the above reaction formulas (1) and (2), the carbon dioxide which is in the stage of passing through the layer of liquid hydrocarbons HC and generating mixed gas M with air A, and the carbon dioxide which is generating mixed gas M with air A above the layer, permeate the layer of liquid hydrocarbons HC due to their affinity for the liquid hydrocarbons HC, which are non-polar liquids, and further, because they are easily dissolved in water W, even though the water W in the lower region is a polar liquid, they migrate to the side of water W and dissolve therein.

[0026] The dissolution promotes the reduction reaction of the formula (1), which in turn promotes the synthesis reaction of the formula (2). As far as the reaction formulas (1) and (2) are concerned, the higher the concentration of the liquid hydrocarbons HC, which can be freely adjusted above the interface, the more the reactions of the formulas (1) and (2) are promoted.

[0027] However, according to the experience of the inventors, it has been found that the higher the concentration of carbon dioxide, the more the reactions of the above formulas (1) and (2) are not promoted, and when the concentration of carbon dioxide above the interface exceeds a certain level, the production of liquid hydrocarbons HC may actually decrease.

[0028] At present, the exact reason why the efficiency of synthesis of liquid hydrocarbons HC decreases when the concentration of carbon dioxide exceeds a certain value is not clear. However, it can be assumed that the function of the photocatalyst in the above reaction formulas (1) and (2) will be reduced if the carbon dioxide concentration exceeds a certain level.

[0029] The appropriate concentration of carbon dioxide at the upper interface depends on the amount of carbon dioxide contained in the water, but in most cases, the appropriate carbon dioxide concentration can be set within the numerical range of 430 ppm to 2000 ppm.

[0030] In the basic configurations (1) and (2) that assume a continuous supply of carbon dioxide, the mixture gas M of carbon dioxide and air A is From the bottom and / or sides of the reactor 1 supply 、 or Carbon dioxide is fed from the bottom of reactor 1 and Air A From the side of reactor 1 The supply can achieve a carbon dioxide concentration in the appropriate range as described above.

[0031] In the case of the configuration of Patent Document 2, in which oxygen nanobubbles are essential, it was assumed that the temperature in the reaction tank 1 would preferably be room temperature, 40°C, and more preferably 30°C (paragraph

[0028] ). In contrast, in the cases of basic configurations (1) and (2), the water temperature includes the natural state, the case where it is cooled, and the case where it is heated, but the water temperature does not have a significant effect on the synthesis efficiency of liquid hydrocarbons HC.

[0032] The basis for this is believed to be that the photocatalyst acting through the reduction reaction of the above formula (1) and the synthesis reaction of liquid hydrocarbons HC of the above formula (2) locally generates molecular vibrations in the water with frequencies orders of magnitude greater than thermal vibrations, and that the thermal vibrations that affect the water temperature have almost no effect on the molecular motion.

[0033] The reduction reaction of the above formula (1) is preferably carried out in a calm state. In such a case, when bubbles of air A or a mixed gas M of carbon dioxide and air A are raised into the water W as in the basic configurations (1) and (2), there is a concern that the calm state may be destroyed and the reduction reaction of the above formula (1) may be hindered. However, in reality, no such destruction has occurred.

[0034] The reason for this is that the rising of the bubbles does not create a vibration state or even a turbulent state in the water W that would interfere with the reduction reaction, and therefore the reduction reaction and the rising of the bubbles can be fully achieved. In fact, even in the case of the conventional technology in which bubbles of air A or a mixed gas M of carbon dioxide and air A are not supplied, the movement of the bubbles of carbon dioxide that are continuously supplied does not cause any particular hindrance to the reduction reaction of the above formula (1).

[0035] In the basic configuration (1), an embodiment is adopted that adjusts the supply amount of air A being mixed or supplied at the bottom and / or side, and in the basic configuration (2), an embodiment is adopted that is characterized by being equipped with a supply amount adjustment device 5 for air A being mixed or supplied at the bottom and / or side, as shown in Figure 2(a). However, FIG. 2(a) shows a case where a supply amount adjusting device 5 for the air A before it is mixed is employed.

[0036] In these embodiments, by adjusting the amount of carbon dioxide, or air A, or mixed gas M of carbon dioxide and air A, the synthesis efficiency of liquid hydrocarbons HC can be adjusted and a preferable carbon dioxide concentration of 430 ppm to 2000 ppm can be set.

[0037] In the basic configuration (1), an embodiment is adopted in which air A is delivered to the upper side of the upper interface and the amount of the delivered air is adjusted, and in the basic configuration (2), an embodiment is adopted in which an air supply source 4 and a supply amount adjustment device 5 are provided above the reaction tank 1, as shown in Figure 2 (b).

[0038] In these embodiments, the supply amount of the mixed gas M of carbon dioxide and air A or the supply amount of air A is kept constant, and by adjusting the supply amount of air A supplied above the water W surface, it is possible to adjust the synthesis efficiency of the liquid hydrocarbons HC and set a preferable carbon dioxide concentration of 430 ppm to 2000 ppm.

[0039] In the two above-mentioned embodiments for adjusting the supply amount, in the basic configuration (1), a configuration characterized by measuring the carbon dioxide concentration above the upper interface is adopted, and in the basic configuration (2), as shown in Figures 2(a) and (b), a configuration in which a carbon dioxide concentration measuring device 6 is provided above the reaction tank 1 is adopted, whereby an accurate carbon dioxide concentration can be set.

[0040] In the basic configuration (1), an embodiment is adopted in which a resistance element for slowing down the movement speed of the bubbles is provided in the layer of liquid hydrocarbons HC, and in the basic configuration (2), in the case of these embodiments, at the stage where the bubbles pass through the layer of liquid hydrocarbons HC, the bubbles generate a mixed gas M of carbon dioxide and air A at a considerable ratio, and as a result of the slowing down of the movement speed of the bubbles as described above, the contact time between the liquid hydrocarbons HC and the bubbles in a mixed state is increased, thereby making it possible to promote the synthesis efficiency of the liquid hydrocarbons HC. The resistor element and the filter of When provided in the water W below the layer of liquid hydrocarbons HC, it is possible to promote the mixing of the supplied air A bubbles with the carbon dioxide bubbles without generating the mixed gas M.

[0041] In the basic configuration (1), an embodiment is adopted in which water W containing oxygen in which nanobubbles have been formed by ultrasonic vibration is supplied to the bottom and / or side of the reaction tank 1, and in the basic configuration (2), an embodiment is adopted in which a supply tank for oxygen in which nanobubbles have been formed in a water tank equipped with an ultrasonic vibration device is connected to the bottom and / or side of the reaction tank 1.

[0042] In these embodiments, oxygen nanobubbles are formed in advance by ultrasonic vibration and then supplied into the reaction vessel 1, thereby making it possible to improve the synthesis efficiency of liquid hydrocarbons HC, while at the same time making it possible to realize the reduction reaction of (1) above in a calm state since no ultrasonic vibration is generated in the reaction vessel 1.

[0043] In the basic configuration (1), an embodiment is adopted in which carbon dioxide and / or air A in which nanobubbles are formed by ultrasonic vibration is supplied to the bottom and / or side of the reaction vessel 1, and in the basic configuration (2), an ultrasonic vibration device is provided. Aquarium In the above, an embodiment characterized in that a supply tank for carbon dioxide and / or air A in which nanobubbles are formed is connected to the bottom and / or side of the reaction tank 1 can be adopted.

[0044] In these embodiments, the nano-bubbled carbon dioxide and / or air A is activated, and the efficiency of synthesis of liquid hydrocarbons HC can be improved.

[0045] Specifically, the nanobubbles narrow the volume of the bubbles of carbon dioxide and / or air A, thereby slowing down the speed at which they move through the water W. This not only makes it easier for the air A supplied without being mixed with carbon dioxide to be mixed with carbon dioxide that is supplied separately, but also reduces the speed at which the liquid hydrocarbons HC move through the layer, thereby increasing the period during which the layer is in contact with the mixed gas M, thereby promoting the improvement of the synthesis efficiency.

[0046] Moreover, since the ultrasonic vibration is realized outside the reaction vessel 1, the reduction reaction of the above formula (1) can be realized in a calm state, similar to the case of the above oxygen nanobubbles.

[0047] In the basic configuration (1), an embodiment can be adopted in which the concentration of carbon dioxide in the mixed gas is 430 ppm to 2000 ppm. In accordance with such an embodiment, in the basic configuration (2), An embodiment characterized in that a shield plate for blocking the upward movement of the mixed gas M of carbon dioxide and air A is provided above the reaction vessel 1 can be adopted. In such an embodiment, the concentration of carbon dioxide in the mixed gas M of carbon dioxide and air A above the interface of the liquid hydrocarbons HC can be set to a concentration significantly higher than 430 ppm, which is approximately equal to that at atmospheric pressure. especially, Multiple Shielding plate Between When a configuration is adopted in which a predetermined gap is provided and the size of the gap can be adjusted, the concentration can be appropriately selected by adjusting the gap.

[0048] In the basic configuration (1), ultraviolet light is irradiated onto dissolved oxygen. do In the basic configuration (2), the oxygen dissolved in the reaction vessel is added to the Irradiate An embodiment characterized by including an ultraviolet ray irradiation device can be adopted. In these embodiments, The amount of dissolved oxygen is reduced by irradiation with ultraviolet light. at least When a part of the catalyst is activated, the efficiency of carbon dioxide reduction can be significantly improved compared to when the catalyst is not activated.

[0049] The basis is that hydrogen peroxide (H 2 O 2 ) is generated by the activation of dissolved oxygen, and as a result, efficient reduction of carbon dioxide can be assumed by the following chemical formula. CO 2 +H 2 O 2 →CO+H 2 +3O 2 / 2 ···(3)

[0050] Hereinafter, an explanation will be given with reference to examples.

Example

[0051] Example 1 is characterized in that in the basic configuration (1), the liquid hydrocarbon HC and the water W in a mixed state flow into the reaction tank 1.

[0052] Due to such a feature, in the reaction tank 1, frequent contact between the liquid hydrocarbon HC flowing into the reaction tank 1 and the bubbles of the gas mixture M of carbon dioxide and air A is realized, which contributes to further promoting the synthesis efficiency of the liquid hydrocarbon HC.

Example

[0053] Example 2 is characterized in that in the basic configuration (2), a supply device for supplying water W to the reaction tank 1 is provided, and a receiving tank for receiving the supply of the liquid hydrocarbon HC from the reaction tank 1 is provided.

[0054] Due to such a feature, in the device of the basic configuration (2), continuous and efficient generation of the liquid hydrocarbon HC can be realized.

Industrial Applicability

[0055] The present invention, which is based on the method of the basic configuration (1) and the apparatus of the basic configuration (2), has the great advantage that liquid hydrocarbons can be efficiently produced by contacting the entire surface of the bubbles with a mixed gas of carbon dioxide and air in the layer in which liquid hydrocarbons are produced, and further by contacting the mixed gas of carbon dioxide and air with the upper interface of the layer, and thus has enormous industrial value. [Explanation of symbols]

[0056] W water A. Air HC Liquid hydrocarbons (abbreviation of hydrocarbon) M A mixture of carbon dioxide and air 1 Reactor 2. Source of carbon dioxide and air mixture 3. Sources of Carbon Dioxide 4. Air supply source 5 Supply amount adjustment device 6. Carbon dioxide concentration measuring equipment

Claims

1. A method for synthesizing liquid hydrocarbons, comprising the steps of: reducing carbon dioxide and water to carbon monoxide and hydrogen via a photocatalyst in a reaction vessel containing water in which carbon dioxide, which is continuously supplied, is dissolved and which is mixed with liquid hydrocarbons; and further synthesizing the liquid hydrocarbons by a chemical reaction between the carbon monoxide and the hydrogen via the photocatalyst, wherein bubbles of a mixed gas of the carbon dioxide and air or air bubbles are supplied from the bottom and / or side of the water, so that the upper interface of a layer of liquid hydrocarbons produced in an upper region of the reaction vessel is maintained in a state of contact with the mixed gas of carbon dioxide and air which has passed through the layer.

2. 2. The method for synthesizing liquid hydrocarbons according to claim 1, further comprising adjusting the amount of air mixed or supplied at the bottom and / or side.

3. 2. The method for synthesizing liquid hydrocarbons according to claim 1, further comprising the step of feeding air to the upper side of said upper interface and adjusting the amount of said air fed.

4. 4. The method for synthesizing liquid hydrocarbons according to claim 2, wherein the concentration of carbon dioxide is measured above the upper interface.

5. 4. The method for synthesizing liquid hydrocarbons according to claim 1, 2 or 3, further comprising providing a resistance element in the layer of liquid hydrocarbons for reducing the movement speed of the bubbles.

6. 4. The method for synthesizing liquid hydrocarbons according to claim 1, 2 or 3, wherein oxygen dissolved in water is in the form of nanobubbles due to ultrasonic vibration.

7. 4. The method for synthesizing liquid hydrocarbons according to claim 1, 2 or 3, characterized in that oxygen-containing water in which nanobubbles have been formed by ultrasonic vibration is supplied to the bottom and / or side of the reaction tank.

8. 4. The method for synthesizing liquid hydrocarbons according to claim 1, 2 or 3, characterized in that carbon dioxide and / or air in which nanobubbles have been formed by ultrasonic vibrations is supplied to the bottom and / or side of the reaction vessel.

9. 4. The method for synthesizing liquid hydrocarbons according to claim 1, 2 or 3, wherein the liquid hydrocarbons and the water in a mixed state flow into a reaction vessel.

10. 4. The method for synthesizing liquid hydrocarbons according to claim 1, 2 or 3, characterized in that the concentration of carbon dioxide in the mixed gas is 430 ppm to 2000 ppm.

11. 4. The method for synthesizing liquid hydrocarbons according to claim 1, 2 or 3, characterized in that the dissolved oxygen is at least partially activated by selectively irradiating it with ultraviolet light as a photocatalyst or by irradiating it with ultraviolet light superimposed on a photocatalyst.

12. An apparatus for reducing carbon dioxide continuously supplied into a reaction tank containing water mixed with liquid hydrocarbons via a photocatalyst into carbon monoxide and hydrogen in the water, and further synthesizing liquid hydrocarbons in a layer form in the upper region of the reaction tank by a chemical reaction between the carbon monoxide and the hydrogen via the photocatalyst, said apparatus for synthesizing liquid hydrocarbons being connected to a photocatalyst means in said reaction tank, and to a source of a mixed gas of carbon dioxide and air or a source of air at the bottom and / or side of said reaction tank.

13. 13. The apparatus for synthesizing liquid hydrocarbons according to claim 12, further comprising a supply amount adjusting device for the air mixed or supplied at the bottom and / or side.

14. 13. The apparatus for synthesizing liquid hydrocarbons according to claim 12, further comprising an air supply source and a supply amount adjusting device provided above the reaction vessel.

15. 15. The apparatus for synthesizing liquid hydrocarbons according to claim 13, further comprising a carbon dioxide concentration measuring device provided above the reaction vessel.

16. 15. The apparatus for synthesizing liquid hydrocarbons according to any one of claims 12, 13 and 14, characterized in that one or more filters are installed in the layer of liquid hydrocarbons.

17. 15. The apparatus for synthesizing liquid hydrocarbons according to claim 12, further comprising an ultrasonic vibration device for forming nanobubbles from oxygen dissolved in the water in the reaction tank.

18. 15. The apparatus for synthesizing liquid hydrocarbons according to any one of claims 12, 13 and 14, characterized in that a supply tank for oxygen in which nanobubbles have been formed in a water tank equipped with an ultrasonic vibration device is connected to the bottom and / or side of the reaction tank.

19. 15. The apparatus for synthesizing liquid hydrocarbons according to any one of claims 12, 13 and 14, characterized in that a supply tank for carbon dioxide and / or air in which nanobubbles are formed in water equipped with an ultrasonic vibration device is connected to the bottom and / or side of the reaction tank.

20. 15. The apparatus for synthesizing liquid hydrocarbons according to claim 12, further comprising a shield plate for blocking the upward movement of the mixed gas of carbon dioxide and air above the reaction vessel.

21. 21. The apparatus for synthesizing liquid hydrocarbons according to claim 20, characterized in that the shielding plate is provided with a predetermined gap, and the degree of the gap can be adjusted.

22. 15. The apparatus for synthesizing liquid hydrocarbons according to any one of claims 12, 13 and 14, characterized in that an ultraviolet ray irradiation device is selected as a photocatalyst or an ultraviolet ray irradiation device is superimposed on a photocatalyst in order to activate at least a portion of the oxygen dissolved in the reaction tank.

23. 15. The apparatus for synthesizing liquid hydrocarbons according to claim 12, further comprising a supply device for supplying water to the reaction tank, and a receiving tank for receiving liquid hydrocarbons from the reaction tank.

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