JP5862147B2 - Carbon dioxide hydrogen reduction apparatus and carbon dioxide hydrogen reduction method - Google Patents

Description

Present invention, the powdery catalyst by the hydrogen reduction reaction carbon dioxide with methane and relates to a hydrogen reduction process of hydrogen reduction apparatus and carbon dioxide of carbon dioxide to produce water.

In recent years, carbon dioxide emissions into the atmosphere derived from the combustion of fossil fuels can have a significant impact on ecosystems and the global environment, and therefore, suppression of carbon dioxide emissions has been demanded worldwide.
For this reason, technology that does not emit carbon dioxide or that reduces carbon dioxide emissions has been developed, and as part of this, technology that fixes carbon dioxide or converts it to other substances has also been developed. Yes.
In a completely closed space such as the International Space Station and rockets, replenishment of materials is not easy, and it is necessary to keep the replenishment and discharge to the minimum necessary at the elemental level.
For this reason, it is required to increase substances that can be recovered by converting the generated carbon dioxide into other substances, and to reduce substances that are replenished and discharged as much as possible at the elemental level.

Therefore, as one of the solutions to these demands, the Sabatier reaction in which carbon dioxide is reduced with hydrogen using a catalyst to obtain methane and water, that is,
CO ₂ + 4H ₂ → CH ₄ + 2H ₂ O
R & D is being conducted to efficiently realize the reduction reaction represented by
For example, in general, the reaction conditions of high temperature (about 300 to 400 ° C.) and normal pressure to about 10 atm are required. A technique capable of efficiently reacting even at about 200 ° C. and atmospheric pressure is known (Patent Document 1).

JP 2009-131835 A

However, although the known catalyst according to Patent Document 1 is highly efficient when an optimum environment is given in the experimental facility, the catalyst is powdery and the particle size is very small. When it is unavoidable that the reaction is carried out continuously with practical equipment, it becomes difficult to pass a large amount of carbon dioxide and hydrogen, which are gases, in order to obtain a practical throughput. There was a problem that the pressure was increased and the apparatus had to be enlarged.
Further, the catalyst since it is - reducing reaction that reacted by heating the, when it is filled as a powder-like temperature control is difficult, that variations in the local temperature decreases the efficiency of the generated reaction There was a problem.

Therefore, the present invention solves the above-mentioned problems, and in a technology for performing a hydrogen reduction reaction of carbon dioxide using a powdered catalyst, a practical throughput can be obtained with a small apparatus, and the reaction temperature can be reduced. It is an object of the present invention to provide a carbon dioxide hydrogen reduction apparatus and a carbon dioxide hydrogen reduction method that are easy to manage and have high reaction efficiency.

The invention according to claim 1 is a carbon dioxide hydrogen reduction apparatus having a reaction vessel containing a powdered catalyst and a heating mechanism for heating the powdered catalyst in the reaction vessel, wherein the powdered catalyst Is supported on a porous structure to constitute an immobilized catalyst, and a plurality of the immobilized catalysts are stacked and fixed inside the reaction vessel, and the heating mechanism includes the immobilized catalyst. The object is solved by having a heater for heating and a temperature adjusting means capable of individually adjusting the temperature of the immobilized catalyst.

In addition to the structure of the carbon dioxide hydrogen reduction apparatus according to claim 1, the invention according to claim 2 is a temperature detection in which the temperature adjusting means individually detects the temperature of the immobilized catalyst inside the reaction vessel. And the temperature control unit that controls the temperature of the heater in accordance with the temperature detected by the temperature detection unit.

The invention according to claim 3 includes, in addition to the configuration of the hydrogen reduction apparatus for carbon dioxide according to claim 2, the reaction vessel is housed in a heating furnace provided with a plurality of the heaters, and the plurality of heaters are respectively The said subject is solved by providing in the position which can heat the some fixed catalyst inside the said reaction container individually.

In addition to the structure of the carbon dioxide hydrogen reduction device according to claim 3, the invention according to claim 4 is configured such that the reaction container is formed by connecting a plurality of container units, and each of the container units has one inside. The above-described problem is solved by being configured to be able to hold an immobilized catalyst, and by providing each of the temperature detection units in the container unit.

In addition to the structure of the carbon dioxide hydrogen reduction device according to claim 2, the invention according to claim 5 is configured such that the reaction container is formed by connecting a plurality of container units, each of which has one container unit inside. The above-mentioned problem is solved by being configured to be able to hold the immobilized catalyst, and by providing the heater and the temperature detection unit in the container unit, respectively.

In addition to the structure of the carbon dioxide hydrogen reduction device according to claim 5, the invention according to claim 6 solves the above problem by providing the heater inside the reaction vessel. .

The invention according to claim 7 is a carbon dioxide hydrogen reduction method in which a powdered catalyst is contained in a reaction vessel and a raw material gas is supplied into the reaction vessel while heating the powdered catalyst to obtain a product. A plurality of immobilized catalysts supported on a porous structure and stacked and fixed inside the reaction vessel, and the temperatures of the plurality of immobilized catalysts are individually adjusted. The above-mentioned problem is solved.

The invention according to the claims 8, in addition to the configuration of the hydrogen reduction method of carbon dioxide according to claim 7, which prior Symbol powdery catalyst was powdered carrier are carried a nanoparticulate ruthenium, the The product is methane gas and water to solve the above-mentioned problems.

The invention according to claim 9 includes, in addition to the constitution of the hydrogen reduction method for carbon dioxide according to claim 7 or claim 8, the temperature of the fixed catalyst is adjusted to less than 300 ° C., and the raw material gas is at atmospheric pressure. Thus, the above-mentioned problem is solved by being supplied into the reaction vessel.

According to the carbon dioxide hydrogen reduction apparatus according to claim 1 and the carbon dioxide hydrogen reduction method according to claim 7, the reaction is performed after the powdered catalyst is supported on the porous structure to constitute the immobilized catalyst. By holding inside the container, the powdered catalyst is not held dense, and gas can pass at an optimal flow rate even at low pressure, so the gas pressure is not increased and the apparatus is enlarged. The optimum throughput can be obtained continuously.
In addition, since the powdered catalyst is supported on the surface including the internal space of the porous structure to constitute the immobilized catalyst, the temperature of the powdered catalyst is optimized by heating and controlling the temperature of the immobilized catalyst. It becomes possible to manage.
Furthermore, since multiple immobilized catalysts are stacked and the temperature is adjusted individually, local temperature variations are suppressed, and there are no parts below the reaction temperature or excessively heated parts. High reaction efficiency can be maintained.

According to the configuration of the second aspect of the present invention, the temperature of the immobilized catalyst can be individually detected and the temperature can be managed by feedback control, so that local temperature variations can be further suppressed.
According to the configuration of the third aspect of the present invention, each of the immobilized catalysts can be individually heated to an optimum temperature, so that more accurate temperature management is possible.
According to the configuration of the present invention, since the immobilized catalyst and the container can be appropriately increased or decreased in units, it is possible to configure a flow path that provides an optimum reaction rate according to the required processing capacity. This makes it possible to design optimally according to the required processing capacity and usage environment.

According to the configuration described in claim 5, since the fixed catalyst and the container including the heater can be appropriately increased or decreased in units, it is not necessary to change the configuration as long as it can be accommodated in the heating furnace. Therefore, it is possible to more easily carry out an optimum design according to the required processing capacity and usage environment.
According to the configuration described in claim 6, since the immobilized catalyst can be heated more efficiently, high reaction efficiency can be maintained with less energy.
According to the configuration described in claim 8, so-called Sabatier reaction can be performed more efficiently.
According to the configuration described in claim 9, it is possible to carry out without preparing environmental conditions that can withstand high temperature and high pressure for the hydrogen reduction reaction of carbon dioxide . Even in a closed space , hydrogen reduction of carbon dioxide can be carried out without wasting space or energy.

The basic structure schematic of the hydrogen reduction device of carbon dioxide and the hydrogen reduction method of carbon dioxide of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The schematic explanatory drawing of the reaction container of the hydrogen reduction apparatus of the carbon dioxide which is 1st Example of this invention. FIG. 3 is a schematic cross-sectional explanatory diagram of FIG. 2. The schematic explanatory drawing of the reaction container of the hydrogen reduction apparatus of the carbon dioxide which is 2nd Example of this invention. FIG. 5 is a schematic cross-sectional explanatory diagram of FIG. 4. The schematic diagram of the fixed catalyst of the experiment example of this invention. The graph which shows the temperature dependence of the reduction rate of a carbon dioxide. Explanatory drawing of experiment of temperature distribution. The graph which shows the experimental result of temperature distribution.

A basic configuration of the carbon dioxide hydrogen reduction apparatus and the carbon dioxide hydrogen reduction method of the present invention is schematically shown in FIG.
Hydrogen gas and carbon dioxide gas, which are raw material gases, are supplied from a hydrogen tank 101 and a carbon dioxide tank 102, respectively, and are mixed to an optimum mixing ratio via a flow control valve 103, and the mixed gas is heated via a main valve 104. It is supplied to the reaction vessel 110 provided with the mechanism 120.
Water and methane gas (including some unreacted raw material gas), which are products reduced in the reaction vessel 110, are discharged downstream of the reaction vessel 110 and collected through the condenser 105.
In the condenser 105, in order to separate water and methane gas which are products, the water is condensed by cooling at an ice temperature.
In addition to the illustrations, valves for adjusting the pressure and flow rate, auxiliary devices for monitoring, control, safety, etc., filters, and the like may be provided at appropriate places.

As shown in FIGS. 2 and 3, the reaction vessel 110 of the carbon dioxide hydrogen reduction apparatus 100 according to the first embodiment of the present invention has a plurality of (in this embodiment, five) container units 111 stacked. In each container unit 111, an immobilized catalyst 130 in which a powdered catalyst is supported on a porous structure is fixedly held.
The heating mechanism 120 is a temperature at which the temperature of the plurality of heaters 141 provided in the heating furnace 140 in which the reaction vessel 110 is accommodated so as to be positioned on the outer periphery of each vessel unit 111 and the temperature of the immobilized catalyst 130 can be individually adjusted. And adjusting means.
The temperature adjusting means includes a temperature detection unit 123 that individually detects the temperature of the immobilized catalyst 130 provided in each container unit 111, and the temperature detection unit 123 according to the temperature detected by the temperature detection unit 123. And a temperature control unit 121 that controls the temperature of the heater 141 at the position of the container unit 111.

Further, in this embodiment, an overall control unit 124 is provided, and by receiving a signal from each temperature control unit 121 or issuing a command, monitoring of the temperature and control status of each unit and overall cross-sectional control are provided.・ It is configured to allow operation.
In the figure, each temperature control unit 121 and the overall control unit 124 are provided independently, but the device itself does not need to be divided as long as it is a control device having these functions.
Moreover, although the temperature detection part 123 is provided in two places for every container unit 111, one place may be sufficient and three or more places may be sufficient.

Furthermore, in this embodiment, the reaction vessel 110 is composed of five vessel units 111, but four or less vessel units, or six or more vessel units 111 may be used depending on the required processing capacity and use environment.
The container units 111 may be connected to each other by detaching them by tightening the flange portion with a bolt or the like. If a plurality of container units 111 having the same design are prepared, they can be easily increased or decreased as necessary. .
In addition, a plurality of immobilized catalysts 130 are stacked in one container unit, and a temperature detection unit and a heater are provided so that the temperature can be individually adjusted for each fixed catalyst 130, and the number of container units is stacked. The number of the immobilized catalysts 130 may be less, and the entire reaction vessel 110 may be configured as one vessel unit.

As shown in FIGS. 4 and 5, the reaction vessel 210 of the carbon dioxide hydrogen reduction device according to the second embodiment of the present invention has a plurality of (in this embodiment, five) vessel units 211 laminated, Inside each container unit 211, an immobilized catalyst 230 in which a powdered catalyst is supported on a porous structure is fixedly held.
The heating mechanism includes a heater 222 provided on the outer periphery of each container unit 211 and temperature adjusting means capable of individually adjusting the temperature of the immobilized catalyst 230.
The temperature adjusting means includes a temperature detection unit 223 that individually detects the temperature of the immobilized catalyst 230 provided in each container unit 211, and the temperature detection unit 223 according to the temperature detected by the temperature detection unit 223. And a temperature control unit 221 that controls the temperature of the heater 222 provided in the container unit 211.

In addition, as in the first embodiment, an overall control unit 224 is provided, and by receiving a signal from each temperature control unit 221 or issuing a command, monitoring of the temperature / control status of each unit and the entire cross-section are performed. It is possible to perform various controls and operations.
Further, as in the first embodiment, various modifications are possible.

Next, experimental results of the carbon dioxide hydrogen reduction apparatus and the carbon dioxide hydrogen reduction method of the present invention will be described below.
In the experimental example of the present invention, as schematically shown in FIG. 6, a powdered catalyst 132 (NPJ-002: Patent Document 1) in which ruthenium as a catalytic metal is supported in the form of nanoparticles on the surface of powdered titanium dioxide. In the porous structure 131 made of silicon carbide was used as an immobilized catalyst 130 (NPJ-002 / SiC).

First, an immobilized catalyst (NPJ-002 / SiC) used in the present invention, a powder catalyst (NPJ-002) as a comparative example, and a pellet catalyst (Ru / Al ₂ O) in which ruthenium is supported on an aluminum oxide carrier. The temperature dependence of the reduction rate of carbon dioxide of ( ₃ : commercial product) is shown in a graph in FIG.
The reduction rate of the immobilized catalyst (NPJ-002 / SiC) and the powdered catalyst (NPJ-002) increases at a temperature lower than that of the conventional pellet-shaped catalyst (Ru / Al ₂ O ₃ ). The immobilized catalyst used (NPJ-002 / SiC) always shows a higher reduction rate than the powdery catalyst (NPJ-002) at the same temperature.
From this, it can be seen that the reaction efficiency can be increased by forming the immobilized catalyst by supporting the powdered catalyst on the porous structure, which is the constitution of the present invention.

Next, an immobilized catalyst (NPJ-002 / SiC) used in the present invention, a powdery catalyst (NPJ-002) as a comparative example, and a pellet catalyst (Ru / Al ₂ ) in which ruthenium is supported on an aluminum oxide support. The temperature distribution when O ₃ : commercial product) is put in a reaction vessel and heated will be described.
As shown in FIG. 8, a plurality of immobilized catalysts (NPJ-002 / SiC) are laminated and fixed inside the reaction vessel 110 of the present invention, the temperature of the present invention is adjusted, and a powdered catalyst (NPJ-002) is obtained. ) And the pellet-shaped catalyst (Ru / Al ₂ O ₃ ) were held in a normal reaction vessel 510 and heated by a conventional method.
Each is set so that the maximum reduction rate can be obtained as a whole, and both the reaction vessels 110 and 210 have a catalyst layer inlet A, a catalyst layer inside B of about 1/3 from the inlet, a catalyst layer inside C of about 2/3, and The temperature at four points at the catalyst layer outlet D and the temperature of the heater for heating were measured.

The result is shown in FIG.
Since the pellet catalyst (Ru / Al ₂ O ₃ ) originally requires a high temperature to obtain a high reduction rate, the heater temperature must be 300 ° C., and the temperature distribution of the reaction vessel 510 is at the inlet. It is very high and decreases at a considerable rate toward the outlet, and the overall energy efficiency required to obtain the maximum reduction rate is poor.
The powdered catalyst (NPJ-002) is higher in energy efficiency than the pelletized catalyst (Ru / Al ₂ O ₃ ) at a heater temperature of 240 ° C., but the temperature distribution in the reaction vessel 510 still varies.

On the other hand, the immobilized catalyst (NPJ-002 / SiC) of the present invention is controlled by using the reaction vessel 110 of the present invention to control the heater temperature between 225 ° C. and 240 ° C. The temperature distribution of the container 110 is substantially uniform, and the whole is maintained in the temperature region where the reduction efficiency is the highest with less energy.
The immobilization catalyst is made of silicon carbide as the porous structure supporting the powdered catalyst, but any material can be used as long as it is stable to the raw material gas, the product, and the operating temperature. good.
The porous structure may have any structure such as a sponge shape, a lattice shape, or a felt shape as long as the porous structure can be held in the reaction vessel and gas can pass therethrough.

Hydrogen reduction method of the hydrogen reduction system and carbon dioxide carbon dioxide according to the present invention, the carbon dioxide is hydrogen reduction reaction is advantageously Sabatier reaction to produce methane and water, in space or the like, the space and energy It has a special effect as achieving limited circulation and reuse of materials with less energy without wasting.

DESCRIPTION OF SYMBOLS 100 ... Carbon dioxide hydrogen reduction apparatus 101 ... Hydrogen tank 102 ... Carbon dioxide tank 103 ... Flow control valve 104 ... Main valve 105 ... Condensers 110, 210 ... Reaction container 111, 211 ... container unit 120 ... heating mechanism 121, 212 ... temperature control unit 222 ... heater 123, 223 ... temperature detection unit 124, 224 ... overall control unit 130 ... Immobilized catalyst 131 ... porous structure 132 ... powder catalyst 140 ... heating furnace 141 ... heater 510 ... reaction vessel (conventional example)

Claims (9)

A hydrogen reduction apparatus for carbon dioxide having a reaction vessel containing a powdered catalyst and a heating mechanism for heating the powdered catalyst in the reaction vessel,
The powdered catalyst is supported on a porous structure to constitute an immobilized catalyst,
A plurality of the immobilized catalysts are configured to be stacked and fixed inside the reaction vessel,
The carbon dioxide hydrogen reduction apparatus, wherein the heating mechanism includes a heater for heating the immobilized catalyst and a temperature adjusting means capable of individually adjusting the temperature of the immobilized catalyst. The temperature adjusting unit individually detects the temperature of the immobilized catalyst inside the reaction vessel, and the temperature control unit controls the temperature of the heater according to the temperature detected by the temperature detecting unit. The hydrogen reduction apparatus for carbon dioxide according to claim 1, comprising: The reaction vessel is accommodated in a heating furnace provided with a plurality of the heaters,
The carbon dioxide hydrogen reduction apparatus according to claim 2, wherein the plurality of heaters are provided at positions where the plurality of immobilized catalysts inside the reaction vessel can be individually heated. The reaction vessel is constituted by connecting a plurality of vessel units,
Each of the container units is configured to hold one immobilized catalyst therein;
The carbon dioxide hydrogen reduction apparatus according to claim 3, wherein the temperature detection unit is provided in each of the container units. The reaction vessel is constituted by connecting a plurality of vessel units,
Each of the container units is configured to hold one immobilized catalyst therein;
The hydrogen reduction apparatus for carbon dioxide according to claim 2, wherein the heater and the temperature detection unit are respectively provided in the container unit. The carbon dioxide hydrogen reduction apparatus according to claim 5, wherein the heater is provided inside the reaction vessel. A method for hydrogen reduction of carbon dioxide which encloses a powdered catalyst in a reaction vessel and supplies a raw material gas into the reaction vessel while heating the powdery catalyst to obtain a product,
A plurality of immobilized catalysts in which the powdery catalyst is supported on a porous structure are stacked and fixed inside the reaction vessel,
A method for hydrogen reduction of carbon dioxide, wherein the temperature of each of the plurality of immobilized catalysts is individually adjusted. The powdery catalyst is a powdery carrier on which nanoparticulate ruthenium is supported,
The method for hydrogen reduction of carbon dioxide according to claim 7, wherein the products are methane gas and water. The temperature of the fixed catalyst is adjusted to less than 300 ° C .;
The method for hydrogen reduction of carbon dioxide according to claim 7 or 8, wherein the source gas is supplied into the reaction vessel at atmospheric pressure.

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