Method for producing stable isotope labeled carbon monoxide and method for producing stable isotope labeled carbon dioxide

The present invention relates to a method for producing stable isotope labeled carbon monoxide and a method for producing stable isotope labeled carbon dioxide.

Priority is claimed on Japanese Patent Application No. 2018-020361, filed Feb. 7, 2018, the content of which is incorporated herein by reference.

Since stable isotope labeled carbon monoxides are rich in reactivity, stable isotope labeled carbon monoxides are useful as a labeling substance and the like in industrial fields such as natural science and medicine, and industrially widely manufactured. As the stable isotope labeled carbon monoxide, there are mainly six stable isotope of 12 C 16 O, 12 C 17 O, 12 C 18 O, 13 C 16 O, 13 C 17 O, and 13 C 18 O.

As a method for concentrating a specific kind of the stable isotope labeled carbon monoxide from carbon monoxide containing a plurality of kinds of stable isotopes, a cryogenic separation method has been known. According to the cryogenic separation method, the stable isotope labeled carbon monoxide ( 13 CO) having 13 C is concentrated to raise the abundance ratio of 13 C and the concentration of 13 CO in carbon monoxide can be increased to, for example, 95 atom % or more.

A concentration method combining the cryogenic separation method and an isotope exchange reaction has also been known (by B. Andreev, “Separation of Isotope of Biogenic Elements in Two-phase Systems”, First edition, ISBN: 9780444529817, Elsevier Science, Dec. 28, 2006, pp 217-245.

According to the method described in “Separation of Isotope of Biogenic Elements in Two-phase Systems”, for example, 12 C 18 O is first concentrated by the cryogenic separation method, and a part of the 12 C 18 O concentrated is converted to 13 C 18 O by the isotope exchange reaction represented by the following formula (1). Next, the 13 C 18 O converted is concentrated again to concentrate 13 CO to 98 to 99 atom %, and thereby the abundance ratio of 13 C is further increased.

12 C 18 O+ 13 C 16 O→ 13 C 18 O+ 12 C 16 O  Formula (1)

On the other hand, according to the cryogenic separation method, it is possible to concentrate a specific kind of the stable isotope labeled carbon monoxide while freely controlling the concentration of 13 CO in carbon monoxide to be less than 95 atom %.

Table 1 shows an example of the abundance ratio of each stable isotope labeled carbon monoxide concentrated by the cryogenic separation method. As shown in Table 1, according to the cryogenic separation method, 13 C 16 O of which the natural abundance ratio is 1.1 atom % can be concentrated to about 92.4 atom %.

Thus, in the prior art, it was possible to concentrate a specific kind of the stable isotope labeled carbon monoxide while freely controlling the abundance ratio of 13 C to be an arbitrary value.

Technical Problem

However, no investigation has been made on the abundance ratio of the stable oxygen isotope in the conventional method described in “Separation of Isotope of Biogenic Elements in Two-phase Systems”. Therefore, in the conventional method, the abundance ratio of the stable oxygen isotope has been left to the conclusion of concentrating 13 CO. That is, it is difficult to control the abundance ratio of a specific kind of the stable oxygen isotope to be an arbitrary value by the conventional method described in “Separation of Isotope of Biogenic Elements in Two-phase Systems”.

When the inventor of the present invention concentrated 13 CO by the conventional method, the abundance ratio of 18 O in the concentrated 13 CO was about 8 to 17 atom %. Thereby, it was found that 13 CO, which was concentrated by the conventional method, may be difficult to apply for industrial applications as they are.

For example, 13 CO, which mainly contains about 15 atom % of 13 C 18 O and about 85 atom % of 13 C 16 O, may not be applicable to industrial or medical application requiring a higher concentration of 13 C 16 O. In this case, a further process is needed to reduce the abundance ratio of 13 C 18 O to less than 1 atom %.

On the other hand, since the abundance ratio of 18 O in 13 CO concentrated by the conventional method is about 8 to 17 atom %, in order to be used to applications requiring a high concentration of 13 C 18 O, there are cases in which further processes are required to increase the abundance ratio of 13 C 18 O to 98 atom % or more.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing stable isotope labeled carbon monoxide capable of controlling the abundance ratio of a specific kind of the stable oxygen isotope to be an arbitrary value, and a method for producing stable isotope labeled carbon dioxide capable of controlling the abundance ratio of a specific kind of the stable oxygen isotope to be an arbitrary value.

Solution to Problem

In order to solve the above problem, the present invention has the following methods.

[1] A method for producing stable isotope labeled carbon monoxide including:

a first mixing step in which carbon monoxide selectively containing at least one kind of stable isotope selected from the group consisting of 12 C 16 O, 12 C 17 O, 12 C 18 O, 13 C 16 O, 13 C 17 O, and 13 C 18 O, and water vapor selectively containing at least one kind of stable isotope selected form the group consisting of H 2 16 O, H 2 17 O and H 2 18 O are mixed to produce stable isotope labeled carbon dioxide: and

a second mixing step in which the stable isotope labeled carbon dioxide produced in the first mixing step and hydrogen are mixed.

[2] The method for producing stable isotope labeled carbon monoxide according to [1], wherein, in the first mixing step, a volume ratio (V 1 /V 2 ) between a flow rate V 1 of the water vapor and a flow rate V 2 of the carbon monoxide is set to 1 to 100.

[3] The method for producing stable isotope labeled carbon monoxide according to [1] or [2], wherein, in the second mixing step, a volume ratio (V 3 /V 4 ) between a flow rate V 3 of the hydrogen and a flow rate V 4 of the stable isotope labeled carbon dioxide is set to 1 to 20.

[4] The method for producing stable isotope labeled carbon monoxide according to any one of [1] to [3], wherein, before the first mixing step, an abundance ratio of stable carbon isotope in the carbon monoxide is controlled to be an arbitrary value in advance.

[5] The method for producing stable isotope labeled carbon monoxide according to any one of [1] to [4], wherein, before the first mixing step, an abundance ratio of stable oxygen isotope in the water vapor is controlled to be an arbitrary value in advance.

[6] The method for producing stable isotope labeled carbon monoxide according to any one of [1] to [5], wherein, after the second mixing step, an abundance ratio of stable carbon isotope is controlled to be an arbitrary value.

[7] The method for producing stable isotope labeled carbon monoxide according to any one of [1] to [6], wherein the second step is performed a plurality of times.

[8] The method for producing stable isotope labeled carbon monoxide according to any one of [1] to [7], wherein the water vapor contains 95 atom % or more of H 2 18 O with respect to a total of 100 atom % of H 2 16 O, H 2 17 O, and H 2 18 O.

[9] The method for producing stable isotope labeled carbon monoxide according to any one of [1] to [7], wherein the at least one kind of stable oxygen isotope in the stable isotope selectively contained in the carbon monoxide and a kind of stable oxygen isotope in the stable isotope selectively contained in the water vapor are different from each other.

[10] The method for producing stable isotope labeled carbon monoxide according to [9], wherein the water vapor selectively contains one or both of H 2 16 O and H 2 17 O.

[11] A method for producing stable isotope labeled carbon dioxide including:

a mixing step in which carbon monoxide selectively containing at least one kind of stable isotope selected from the group consisting of 12 C 16 O, 12 C 17 O, 12 C 18 O, 13 C 16 O, 13 C 17 O, and 13 C 18 O and water vapor selectively containing at least one kind of stable isotope selected from the group consisting of H 2 16 O, H 2 17 O, and H 2 18 O are mixed.

Advantageous Effects of Invention

According to the present invention, it is possible to control the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide or the stable isotope labeled carbon dioxide to be an arbitrary value.

FIG. 1 is a schematic diagram showing an example of a producing apparatus applicable to a method for producing stable isotope labeled carbon monoxide according to a first embodiment.

FIG. 2 is a schematic diagram showing an example of a producing apparatus applicable to a method for producing stable isotope labeled carbon monoxide according to a third embodiment.

In the present description, “selectively containing stable isotope” means containing a specific kind of stable isotope more than the natural abundance ratio.

Hereinafter, a method for producing stable isotope labeled carbon monoxide and a method for producing stable isotope labeled carbon dioxide according to one embodiment of the present invention will be described in detail with reference to the drawings. In order to make the features easier to understand, there are cases where the characteristic portion is enlarged for the sake of convenience, and the dimensional ratio and so on of each component is not necessarily the same as the actual.

First Embodiment

FIG. 1 is a schematic diagram showing an example of a producing apparatus 1 applicable to a method for producing stable isotope labeled carbon monoxide according to first embodiment. In other words, the producing apparatus 1 is an apparatus in which the abundance ratio of a specific kind of stable isotope in carbon monoxide containing a plurality of kinds of stable isotopes is controlled. As shown in FIG. 1 , the producing apparatus 1 includes supply sources 3 , 4 , and 5 , supply lines L 1 , L 2 , and L 4 , a connection line L 3 , a lead-out line L 5 , catalyst tubes C 1 and C 2 , temperature control device 6 and 7 , and dehumidifiers F 1 and F 2 .

The supply line L 1 has a first end connected to the supply source 3 , and a second end connected to the primary side (upstream side) of the catalytic tube C 1 . The supply line L 1 is provided with a flow regulator M 1 and a heat exchanger H 1 in this order from the primary side.

The supply line L 2 has a first end connected to the supply source 4 , and a second end connected to a supply line L 1 between the heat exchanger H 1 and the catalytic tube C 1 . The supply line L 2 is provided with a pump P and a heat exchanger H 2 in this order from the primary side.

The connection line L 3 has a first end connected to the secondary side (downstream side) of the catalytic tube C 1 and a second end connected to the primary side of the catalytic tube C 2 . Thereby, the connection line L 3 connects between the secondary side of the catalyst tube C 1 and the primary side of the catalytic tube C 2 . The connection line L 3 is provided with the dehumidifier F 1 and a heat exchanger H 3 in this order from the primary side.

The supply line L 4 has a first end connected to the supply source 5 and a second end connected to the connection line L 3 between the heat exchanger H 3 and the catalytic tube C 2 . The supply line L 4 is provided with a flow regulator M 2 and a heat exchanger H 4 in this order from the primary side.

The lead-out line L 5 has a first end connected to the secondary side of the catalyst tube C 2 , and a second end (not shown) connected to a storage container (not shown). The lead-out line L 5 is provided with the dehumidifier F 2 . In addition, the lead-out line L 5 is provided with an analyzer (not shown) at the secondary side of the dehumidifier F 2 . As the analyzer (not shown), FT-IR, gas chromatography and the like are exemplary examples; however, the analyzer is not limited to these examples.

A catalyst provided in the catalyst tubes C 1 and C 2 is not particularly limited. Examples of the catalyst provided in the catalyst tubes C 1 and C 2 include Cu/Zn/Al 2 O 3 based catalysts, Cu/Cr/Fe based catalysts, Cu/Zn/Al/Mg based catalysts, Fe/Cr/Cu/C based catalysts, and Ni/Al based catalysts.

The temperature control device 6 is not particularly limited as long as it can control the temperature of the heat exchangers H 1 and H 2 and the catalyst tube C 1 . Similarly, the temperature control device 7 is not particularly limited as long as it can control the temperature of the heat exchangers H 3 and H 4 and the catalyst tube C 2 .

The supply source 3 is a supply source of carbon monoxide. The supply source 3 supplies carbon monoxide into the catalyst tube C 1 via the supply line L 1 . The carbon monoxide selectively contains at least one kind of stable isotope selected from the group consisting of 12 C 16 O, 12 C 17 O, 12 C 18 O, 13 C 16 O, 13 C 17 O, and 13 C 18 O. The carbon monoxide may contain a plurality of kinds of stable isotopes. In the present description, “a plurality of kinds of stable isotope labeled carbon monoxides” means at least two kinds of stable isotopes selected from the group consisting of 12 C 16 O, 12 C 17 O, 12 C 18 O, 13 C 16 O, 13 C 17 O, and 13 C 18 O.

The amount of the specific stable isotope selectively contained in the carbon monoxide is preferably 30 atom % or more, more preferably 50 atom % or more, still more preferably 90 atom % or more, and particularly preferably 95 atom % or more with respect to the total of 100 atom % of all kinds of stable isotopes contained in the carbon monoxide. When the amount of the stable isotope selectively contained in the carbon monoxide is within this range, the abundance ratio of the specific stable carbon isotope and the specific stable oxygen isotope in the stable isotope labeled carbon monoxide produced by the method of the present embodiment can be easily controlled to be an arbitrary value.

In the present description, the specific stable carbon isotope is either one or both of 12 C and 13 C, and the specific stable oxygen isotope is at least one kind selected from the group consisting of 16 O, 17 O and 18 O.

It is preferable that the abundance ratio of 12 C or 13 C in the stable isotope selectively contained in the carbon monoxide be controlled to be an arbitrary value in advance. Thereby, the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide obtained by the method of this embodiment can be easily controlled to be an arbitrary value. At the same time, the abundance ratio of the specific stable carbon isotope in the stable isotope labeled carbon monoxide can also be easily controlled to be an arbitrary value.

Further, it is preferable that the specific stable isotope selectively contained in the carbon monoxide include either 12 C or 13 C. When the specific stable isotope selectively contained in the carbon monoxide includes either one of 12 C or 13 C, the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide produced by the method of this embodiment can be easily controlled to be an arbitrary value. At the same time, the abundance ratio of the specific stable carbon isotope in the stable isotope labeled carbon monoxide produced by the method of this embodiment can also be easily controlled to be an arbitrary value.

The carbon monoxide may be prepared by concentrating a specific kind of stable isotope by the cryogenic separation method. In addition, the carbon monoxide selectively containing specific stable isotope may be prepared by combining the cryogenic separation method and the isotope exchange reaction. For example, the abundance ratio of the stable carbon isotope in the carbon monoxide can be controlled to be an arbitrary value in advance by the cryogenic separation method or the combination of the cryogenic separation method and the isotope exchange reaction.

The supply source 4 is a supply source of water. The water supplied from the supply source 4 is heated by the heat exchanger 2 to produce water vapor. The water vapor produced is supplied into the catalyst tube C 1 via the supply line L 2 and a part of the supply line L 1 . The water vapor selectively contains at least one kind of stable isotope selected from the group consisting of H 2 16 O, H 2 17 O, and H 2 18 O.

The amount of the specific stable isotope selectively contained in the water vapor is preferably 30 atom % or more, more preferably 50 atom % or more, still more preferably 90 atom % or more, and particularly preferably 95 atom % or more with respect to the total of 100 atom % of all kinds of stable isotopes contained in the water vapor. When the amount of the specific stable isotope selectively contained in the water vapor is within this range, the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide obtained by the method of this embodiment can be easily controlled to be an arbitrary value.

In the present embodiment, it is preferable that the water vapor selectively contain one kind of H 2 16 O, H 2 17 O, and H 2 18 O as the specific stable isotope. When water vapor selectively contains one kind of stable isotope of H 2 16 O, H 2 17 O, and H 2 18 O as the specific stable isotope, it is possible to control the abundance ratio of the specific oxygen stable isotope in the stable isotope labeled carbon monoxide obtained by the method of this embodiment to a high arbitrary value, that is, concentrate the specific oxygen stable isotope in the stable isotope labeled carbon monoxide.

For example, when the water vapor selectively contains selectively only H 2 18 O as the specific stable isotope, the abundance ratio of 18 O in the obtained stable isotope labeled carbon monoxide can be concentrated to be an arbitrary value.

The supply source 5 is a supply source of hydrogen. The supply source 5 supplies hydrogen into the catalyst tube C 2 via the supply line L 4 and a part of the connection line L 3 .

In the producing apparatus 1 having the above-described configuration, the carbon monoxide and the water vapor can be mixed in the catalyst tube C 1 to produce a reaction product containing stable isotope labeled carbon dioxide. The stable isotope labeled carbon dioxide which can be produced in the catalyst tube C 1 selectively contains at least one kind of stable isotope labeled carbon dioxide selected from the group consisting of 12 C 16 O 16 O, 12 C 17 O 17 O, 12 C 18 O 18 O, 12 C 16 O 17 O, 12 C 17 O 18 O, 12 C 18 O 16 O, 13 C 16 O 16 O, 13 C 17 O 17 O, 13 C 18 O 18 O, 13 C 16 O 17 O, 13 C 17 O 18 O, and 13 C 18 O 16 O.

Moreover, the stable isotope labeled carbon dioxide may contain a plurality of kinds of carbon dioxides stable isotopes. Examples of the plurality of kinds of carbon dioxides include at least two selected from the group consisting of 12 C 16 O 16 O, 12 C 17 O 17 O, 12 C 18 O 18 O, 12 C 16 O 17 O, 12 C 17 O 18 O, 12 C 18 O 16 O, 13 C 16 O 16 O, 13 C 17 O 17 O, 13 C 18 O 18 O, 13 C 16 O 17 O, 13 C 17 O 18 O, and 13 C 18 O 16 O.

The amount of the specific kind of stable isotope labeled carbon dioxide selectively contained in the stable isotope labeled carbon dioxide is preferably 30 atom % or more, more preferably 50 atom % or more, still more preferably 90 atom % or more, and particularly preferably 95 atom % or more with respect to the total of 100 atom % of all kinds of stable isotope labeled carbon dioxides. When the amount of the specific kind of stable isotope labeled carbon dioxide selectively contained in the stable isotope labeled carbon dioxide is within this range, the abundance ratio of the specific stable carbon isotope and the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide produced by the apparatus 1 can be easily controlled to arbitrary values.

In the apparatus 1 , it is preferable to select the stable isotope labeled carbon monoxide and the water vapor such that the stable isotope labeled carbon dioxide contains at least one kind selected from the group consisting of 12 C 16 O 16 O, 12 C 17 O 17 O, 12 C 18 O 18 O, 13 C 16 O 16 O, 13 C 17 O 17 O, and 13 C 18 O 18 O as the specific stable isotope labeled carbon dioxide. In apparatus 1 , it is more preferable to select the stable isotope labeled carbon monoxide and the water vapor such that the stable isotope labeled carbon dioxide contains at least one kind selected from the group consisting of 12 C 17 O 17 O, 12 C 18 O 18 O, 13 C 16 O 16 O, 13 C 17 O 17 O, and 13 C 18 O 18 O as the specific stable isotope labeled carbon dioxide. When the stable isotope labeled carbon dioxide selectively contains at least one kind selected from the group consisting of 12 C 16 O 16 O, 12 C 17 O 17 O, 12 C 18 O 18 O, 13 C 16 O 16 O, 13 C 17 O 17 O, and 13 C 18 O 18 O as the specific stable isotope labeled carbon dioxide, the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide produced by the method of the present embodiment can be easily controlled to be an arbitrary value.

As a method for producing the stable isotope labeled carbon dioxide selectively containing at least one kind selected from the group consisting of 12 C 16 O 16 O, 12 C 17 O 17 O, 12 C 18 O 18 O, 13 C 16 O 16 O, 13 C 17 O 17 O, and 13 C 18 O 18 O as the specific stable isotope labeled carbon dioxide, a method for producing stable isotope labeled carbon dioxide according to the present embodiment which is explained below can be used, but the method is not limited thereto.

(Method for Producing Stable Isotope Labeled Carbon Monoxide)

Next, a method for producing stable isotope labeled carbon monoxide of the first embodiment will be described with reference to FIG. 1 . In order to simplify the explanation, in the following first embodiment, a case, in which the carbon monoxide selectively contains only 13 C 16 O as the specific stable isotope, and the water vapor selectively contains only H 2 18 O as the specific stable isotope, will be described as one embodiment.

First, carbon monoxide and water vapor are mixed in the method for producing stable isotope labeled carbon monoxide according to the first embodiment. Specifically, carbon monoxide is supplied from the supply source 3 into the catalyst tube C 1 , water is supplied from the supply source 4 into the catalyst tube C 1 , and the carbon monoxide and the water are mixed in the catalyst tube C 1 . At this time, the carbon monoxide flowing through the supply line L 1 is regulated in flow rate by the flow regulator M 1 . After the carbon monoxide is heated by the heat exchanger H 1 , the carbon monoxide heated is supplied into the catalyst tube C 1 . In addition, the water flowing through the supply line L 2 is regulated in pressure by the pump P, heated and vaporized by the heat exchanger H 2 , and then supplied into the catalyst tube C 1 .

The equilibrium reaction shown in the following equation (2) occurs by mixing the carbon monoxide and the water vapor in the catalyst tube C 1 . When the equilibrium reaction shown in the following equation (2) occurs, the oxygen atom ( 18 O in the present embodiment) in the specific stable isotope selectively contained in the water vapor is introduced into the stable isotope ( 13 C 16 O in the present embodiment) selectively contained in the carbon monoxide, and 13 C 16 O 18 O is produced in the present embodiment.

13 C 16 O+H 2 18 O⇔ 13 C 18 O 16 O+H 2   Formula (2)

In the equilibrium state shown in the formula (2), an isotope exchange reaction shown in the following formula (3) occurs by excessively supplying the water vapor (H 2 18 O in the present embodiment). When the reaction shown in in the following formula (3) occurs, the oxygen atom in 13 C 18 O 16 O is exchanged with 18 O contained in an excessive amount of the water vapor to produce 13 C 18 O 18 O.

13 C 18 O 16 O+H 2 18 O→ 13 C 18 O 18 O+H 2 16 O  Formula (3)

Next, the stable isotope labeled carbon dioxide selectively containing 13 C 18 O 18 O is mixed with hydrogen.

Specifically, the reaction product of the formula (3) from the catalyst tube C 1 is introduced into the connection line L 3 , moisture contained in the reaction product is removed by the dehumidifier F 1 , heated by the heat exchanger H 3 , and then supplied into the catalyst tube C 2 as the stable isotope labeled carbon dioxide selectively containing 13 C 18 O 18 O. On the other hand, the hydrogen flowing through the supply line L 4 is regulated in flow rate by the flow regulator M 2 , heated by the heat exchanger H 4 , and then supplied into the catalyst tube C 2 .

In the catalyst tube C 2 , the chemical reaction shown in the following formula (4) occurs by in particular excessively supplying hydrogen. The temperature at which the chemical reaction shown in the following formula (4) is carried out may be adjusted appropriately according to the kind of the catalyst provided in the catalyst tube C 1 , and is not particularly limited.

13 C 18 O 18 O+H 2 → 13 C 18 O+H 2 18 O  Formula (4)

Thereafter, moisture contained the reaction product of the chemical reaction represented by the formula (4) is removed by the dehumidifier F 2 and then the reaction product is led into a storage container (not shown) as stable isotope labeled carbon monoxide selectively containing 13 C 18 O via the lead-out line L 5 . At this time, the abundance ratio of the specific stable isotope labeled carbon monoxide ( 13 C 18 O in this embodiment) may be analyzed by an analyzer (not shown).

As a result of the chemical reaction represented by the formula (4), an oxygen atom is transferred from the specific stable isotope labeled carbon dioxide ( 13 C 18 O 18 O in the present embodiment) selectively contained in the stable isotope labeled carbon dioxide to hydrogen. As a result, it is possible to introduce the specific oxygen atom isotope ( 18 O in the present embodiment) to the specific stable isotope ( 13 C 16 O in the present embodiment). By such a chemical reaction, it is possible to easily and effectively change the abundance ratio of the oxygen atom isotope in carbon monoxide, and selectively produce the specific stable isotope labeled carbon monoxide.

When mixing the carbon monoxide and the water vapor, the volume ratio (V 1 /V 2 ) between the flow rate V 1 of the water vapor and the flow rate V 2 of the carbon monoxide is preferably 1 to 100. However, the volume ratio (V 1 /V 2 ) can be appropriately adjusted according to the abundance ratio of the stable carbon isotope of the stable oxygen isotope in the specific stable isotope selectively contained in carbon monoxide.

In particular, as described in the present embodiment, when controlling the abundance ratio of the stable oxygen isotope in the carbon monoxide selectively containing 13 C 16 O, the volume ratio (V 1 /V 2 ) is preferably from 1 to 10, and more preferably from 5 to 10. When the volume ratio (V 1 /V 2 ) is equal to or more than the lower limit value, the chemical reaction between the carbon monoxide and the water vapor is easily proceeded. When the volume ratio (V 1 /V 2 ) is equal to or less than the upper limit value, it is advantageous from the viewpoint of cost.

The temperature at which the carbon monoxide and the water vapor are mixed is not particularly limited, and the temperature may be, for example, 100 to 700° C. The temperature may be appropriately adjusted according to the catalyst provided in the catalyst tube C 1 .

When mixing the stable isotope labeled carbon dioxide and hydrogen, the volume ratio (V 3 /V 4 ) between the flow rate V 3 of the hydrogen and the flow rate V 4 of the stable isotope labeled carbon dioxide is preferably 1 to 20, and more preferably 5 to 20. When the volume ratio (V 3 /V 4 ) is equal to or more than the lower limit value, the chemical reaction between the stable isotope labeled carbon dioxide and the hydrogen is easily proceeded. When the volume ratio (V 3 /V 4 ) is equal to or less than the upper limit value, it is advantageous from the cost aspect.

The temperature at which the stable isotope labeled carbon dioxide and the hydrogen are mixed is not particularly limited, and the temperature may be, for example, 600 to 800° C. The temperature may be appropriately adjusted according to the catalyst provided in the catalyst tube C 2 .

In the present embodiment, it is preferable to perform at least one of the following operations A1 to A3.

Operation A1: Before mixing the carbon monoxide and the water vapor, an operation for controlling the abundance ratio of the stable carbon isotope in the carbon monoxide to be an arbitrary value in advance. Operation A2: Before mixing the carbon monoxide and the water vapor, an operation for controlling the abundance ratio of the stable oxygen isotope in the water vapor to be an arbitrary value in advance Operation A3: After mixing the stable isotope labeled carbon dioxide and the hydrogen, an operation for controlling the abundance ratio of the stable carbon isotope in the stable isotope labeled carbon monoxide to be an arbitrary value.

When at least one of the operations A1 to A3 is performed, the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide obtained by the method of this embodiment can be easily controlled to be an arbitrary value, and at the same time, the abundance ratio of the specific stable carbon isotope in the stable isotope labeled carbon monoxide obtained by the method of this embodiment can also be easily controlled to be an arbitrary value.

As a method for controlling the abundance ratio of the stable carbon isotope to be an arbitrary value in operations A1 and A3, a method in which the stable isotope labeled carbon monoxide or the stable isotope labeled carbon dioxide in the producing apparatus 1 is led into a storage container from the lead-out line L 5 , and the cryogenic separation method or the method combining the cryogenic separation method and the isotope exchange reaction is carried out, is an exemplary example.

Either one of the operations A1 to A3 may be performed independently, and plural operations may be performed in combination. Even when plural operations are performed in combination, an effect by each operation combined can be obtained.

The operation A2 will be described in more detail. When the abundance ratio of the stable oxygen isotope in the water vapor is controlled to be an arbitrary value in advance before mixing the carbon monoxide and the water vapor in the first embodiment, the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon dioxide obtained can be easily controlled to be an arbitrary value. As a result, it is possible to freely control the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide obtained.

For example, before mixing the carbon monoxide and the water vapor, when the abundance ratio of the specific stable oxygen isotope in the water vapor is controlled to be an arbitrary value in advance, for example, when the water vapor containing 95 atom % of H 2 18 O with respect to the total of 100 atom % of H 2 16 O, H 2 17 O and H 2 18 O, the abundance ratio of 18 O in the stable isotope labeled carbon dioxide produced can be controlled to 95 atom % or more. As a result, the abundance ratio of 13 C 18 O in the stable isotope labeled carbon monoxide ratio produced can be arbitrarily controlled and increased to 95 atom % or more.

In this way, it is possible to arbitrarily control the abundance ratio of the specific stable oxygen isotope ( 18 O in the present embodiment) in the stable isotope labeled carbon dioxide produced and the stable isotope labeled carbon monoxide produced by arbitrarily changing the abundance ratio of the stable oxygen isotope contained in the specific stable isotope (H 2 18 O in the present embodiment) contained in the water vapor.

(Method for Producing Stable Isotope Labeled Carbon Dioxide)

A method for producing stable isotope labeled carbon dioxide will be explained. In the present embodiment, carbon monoxide selectively containing at least one kind of stable isotope selected from the group consisting of 12 C 16 O, 12 C 17 O, 12 C 18 O, 13 C 16 O, 13 C 17 O, and 13 C 18 O and water vapor selectively containing at least one kind of stable isotope selected from the group consisting of H 2 16 O, H 2 17 O, and H 2 18 O are mixed.

Specifically, the carbon monoxide is supplied from the supply source 3 into the catalyst tube C 1 , the water is supplied from the supply source 4 into the catalyst tube C 1 after being vaporized, and the carbon monoxide and the water vapor are mixed in the catalyst tube C 1 . Moisture is removed from the reaction product produced by the chemical reaction between the carbon monoxide and hydrogen by the dehumidifier F 1 . Then, stable isotope labeled carbon dioxide (the reaction product) is led into the storage container, which is not shown in figures, through the connection line L 3 and the lead-out line L 5 . Thereby, it is possible to produce the stable isotope labeled carbon dioxide selectively containing the specific kind of stable isotope labeled carbon dioxide.

Preferable conditions and modes for mixing the carbon monoxide and the water vapor are the same as the method for producing stable isotope labeled carbon monoxide of the first embodiment.

(Effects)

In the first embodiment as described above, the carbon monoxide selectively containing at least one kind of stable isotope selected from the group consisting of 12 C 16 O, 12 C 17 O, 12 C 18 O, 13 C 16 O, 13 C 17 O, and 13 C 18 O and the water vapor selectively containing at least one kind of stable isotope selected from the group consisting of H 2 16 O, H 2 17 O, and H 2 18 O are mixed to produce the stable isotope labeled carbon dioxide selectively containing the specific stable isotope labeled carbon dioxide. Therefore, it is possible to introduce the specific oxygen atom isotope derived from the water vapor to the carbon monoxide. Therefore, according to the method for producing stable isotope labeled carbon monoxide in the first embodiment, it is possible to arbitrarily control the abundance ratio of the specific oxygen atom isotope without addition of a process for decreasing or increasing the abundance ratio of the specific stable oxygen isotope.

Second Embodiment

Below, a second embodiment will be described with reference to FIG. 1 . In the description of the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and an explanation thereof will be omitted.

In the second embodiment, a case in which carbon monoxide selectively contains 13 C 18 O as specific stable isotope and water vapor selectively contains either one or both of H 2 16 O and H 2 17 O as specific stable isotope.

First, in the second embodiment, carbon monoxide and water vapor are supplied into the catalyst tube C 1 and mixed together. Thereby, at least one of the equilibrium reactions represented by the following formulas (5) to (10) occurs depending on the kind of stable isotope contained in the carbon monoxide.

13 C 18 O+H 2 16 O⇔ 13 C 18 O 16 O+H 2   Formula (5)

13 C 18 O+H 2 17 O⇔ 13 C 17 O 18 O+H 2   Formula (6)

13 C 17 O+H 2 16 O⇔ 13 C 16 O 17 O+H 2   Formula (7)

13 C 17 O+H 2 17 O⇔ 13 C 17 O 17 O+H 2   Formula (8)

13 C 16 O+H 2 16 O⇔ 13 C 16 O 16 O+H 2   Formula (9)

13 C 16 O+H 2 17 O⇔ 13 C 16 O 17 O+H 2   Formula (10)

In the equilibrium state represented by the formula (5), when H 2 16 O is excessively supplied, the isotope exchange reaction shown in the following formula (11) occurs. When the reaction shown in the following formula (11) occurs, the oxygen atom in 13 C 18 O 16 O is exchanged with 16 O contained in an excessive amount of water vapor, and 13 C 16 O 16 O is produced.

13 C 18 O 16 O+H 2 16 O→ 13 C 16 O 16 O+H 2 18 O  Formula (11)

In the equilibrium state represented by the formula (6), when H 2 17 O is excessively supplied, the isotope exchange reaction shown in the following formula (12) occurs. When the reaction shown in the following formula (12) occurs, the oxygen atom in 13 C 17 O 18 O is exchanged with 17 O contained in an excessive amount of the water vapor, and 13 C 17 O 17 O is produced.

13 C 17 O 18 O+H 2 17 O→ 13 C 17 O 17 O+H 2 18 O  Formula (12)

As shown in the formulas (11) and (12), in the second embodiment, the oxygen atom in 13 C 18 O is exchanged with 16 O or 17 O, and the abundance ratio of 18 O in the stable isotope labeled carbon dioxide is decreased. The chemical reaction shown in the formula (13) mainly occurs in the catalyst tube C 2 by supplying the stable isotope labeled carbon dioxide with a reduced abundance ratio of 18 O and hydrogen into the catalyst tube C 2 and mixing them. When the chemical reaction shown in the formula (13) occurs, the stable isotope labeled carbon monoxide with a reduced abundance ratio of 18 O is produced.

13 COO+H 2 → 13 CO+H 2 O  Formula (13)

In the formula (13), O is either 16 O or 17 O.

In the method for producing the stable isotope labeled carbon monoxide of the second embodiment, the conditions such as the flow rate and the temperature at the time of carrying out the reaction shown in the formulas (5) to (13) are the same as those of the formulas (2) to (4).

(Effects)

In the second embodiment described above, the carbon monoxide selectively containing 13 C 18 O and the water vapor selectively containing either or both of H 2 16 O and H 2 17 O are mixed. Therefore, the carbon oxide stable isotope with a reduced abundance ratio of 18 O is produced. According to the method for producing stable isotope labeled carbon monoxide of the second embodiment, it is possible to reduce the abundance ratio of 18 O to be an arbitrary value without adding a step of decreasing the amount of 18 O.

According to the second embodiment, even when the carbon monoxide ( 13 C 18 O in the present embodiment), which includes 1 to 20 atom % of stable isotope having 18 O with respect to the total of 100 atom % of the stable isotope labeled carbon monoxide having 16 O, the stable isotope labeled carbon monoxide having 17 O, and the stable isotope labeled carbon monoxide having 18 O, is used, it is possible to control the abundance ratio of 18 O in the stable isotope labeled carbon dioxide produced to 8 atom % or less. It is possible to decrease the abundance ratio of 13 C 18 O in the stable isotope labeled carbon monoxide produced to less than 8 atom %, that is, dilute 13 C 18 O by the method according to the second embodiment.

In this way, according to the second embodiment, at least one kind of stable oxygen isotope ( 18 O in the present embodiment) contained in the stable isotope selectively contained in the carbon monoxide and the stable oxygen isotope ( 16 O or 17 O in the present embodiment) contained in the stable isotope selectively contained in the water vapor are different from each other. Therefore, the abundance ratio of the specific stable oxygen isotope ( 18 O in the present embodiment) in the stable isotope labeled carbon dioxide, which is produced by mixing the carbon monoxide and the water vapor, can be decreased to be an arbitrary value, that is, the specific stable oxygen isotope ( 18 O in the present embodiment) in the stable isotope labeled carbon dioxide can be diluted. It is possible to decrease the abundance ratio of the specific stable oxygen isotope in the stable isotope labeled carbon monoxide produced by mixing the stable isotope labeled carbon dioxide produced and hydrogen.

The method for producing stable isotope labeled carbon monoxide according to the second embodiment described above is a method for diluting the specific kind of stable isotope by reducing the abundance ratio of specific kind of stable isotope in the carbon monoxide containing a plurality of kinds of stable isotopes. In the second embodiment, the case in which the water vapor selectively contains one or both of H 2 16 O and H 2 17 O has been described as an example, but the second embodiment is not limited to this example. For example, in order to reducing the abundance ratio of 13 C 16 O in carbon monoxide to be an arbitrary value, that is, to dilute, water vapor which selectively contains either or both H 2 17 O and H 2 18 O and carbon monoxide may be mixed.

Third Embodiment

Below, a third embodiment will be described with reference to FIG. 1 . In the description of the third embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and an explanation thereof will be omitted.

FIG. 2 is a schematic diagram showing one example of a producing apparatus 2 which can be used in a method for producing stable isotope labeled carbon monoxide of the third embodiment. As shown in FIG. 2 , the producing apparatus 2 includes supply sources 3 , 4 , and 5 and supply lines L 1 , L 2 , L 4 , and L 7 , catalyst tubes C 1 , C 2 , and C 3 , temperature control devices 6 , 7 , and 8 , connection lines L 3 and L 6 , a lead-out line L 8 and dehumidifiers F 1 , F 2 , and F 3 .

The connection line L 6 has a first end connected to the secondary side of the catalyst tube C 2 and a second end connected to the primary side of the catalyst tube C 3 . Thereby, the connection line L 6 connects between the secondary side of the catalyst tube C 2 and the primary side of the catalyst tube C 3 . The connection line L 6 is provided with the dehumidifier F 2 and a heat exchanger H 5 in this order from the primary side.

The supply line L 7 has a first end connected to the supply line L 4 between the supply source 5 and the flow regulator M 2 and a second end connected to the connection line L 6 between the heat exchanger H 5 and the catalyst tube C 3 . The supply line L 7 is provided with a flow regulator M 3 and a heat exchanger H 6 in this order from the primary side.

The supply source 5 is a supply source of hydrogen. In the third embodiment, the supply source 5 supplies hydrogen into the catalyst tube C 2 via supply line L 4 and a part of the connection line L 3 . In addition, the supply source 5 also supplies hydrogen into the catalyst tube C 3 via a part of the supply line L 4 , the supply line L 7 , and a part of the connection line L 6 .

As the catalyst of the catalyst tube C 3 , the same catalyst as that of the catalyst tubes C 1 and C 2 is an exemplary example.

The temperature control device 8 is not particularly limited as long as it can adjust the temperature of the heat exchangers H 5 and H 6 and the catalyst tube C 3 .

The lead-out line L 8 has a first end connected to the secondary side of the catalyst tube C 3 , and a second end (not shown) is connected to a storage container (not shown). The lead-out line 8 is provided with the dehumidifier F 3 . In addition, the lead-out line 8 is provided with an analyzer (not shown) at the secondary side of the dehumidifier F 3 .

Next, a method for producing stable isotope labeled carbon monoxide according to the third embodiment will be described. In order to simplify the explanation, in the following third embodiment as well as the first embodiment, a case in which carbon monoxide selectively contains only 13 C 16 O as specific stable isotope and water vapor selectively contains only H 2 18 O as specific stable isotope will be described as an embodiment. However, the third embodiment is not limited to this embodiment.

First, carbon monoxide and water vapor are mixed in the method for producing stable isotope labeled carbon monoxide of the third embodiment. Specifically, carbon monoxide is supplied from the supply source 3 into the catalyst tube C 1 , and water vapor is supplied from the supply source 4 into the catalyst tube C 1 . Thereby, an equilibrium reaction expressed by the following equation (2) occurs in the catalyst tube C 1 .

13 C 16 O+H 2 18 O⇔ 13 C 18 O 16 O+H 2   Formula (2)

In the equilibrium state shown in the formula (2), an isotope exchange reaction shown in the following formula (3) occurs by excessively supplying the water vapor. When the reaction shown in the following formula (3) occurs, the oxygen atom in 13 C 18 O 16 O is exchanged with 18 O contained in an excessive amount of the water vapor to produce 13 C 18 O 18 O.

13 C 18 O 16 O+H 2 18 O→ 13 C 18 O 18 O+H 2 16 O  Formula (3)

Next, in the method for producing stable isotope labeled carbon monoxide of the third embodiment, the stable isotope labeled carbon dioxide and hydrogen are mixed. 13 C 18 O 18 O which is the reaction product of the formula (3) passes through the connection line L 3 . After removal of moisture by the dehumidifier F 1 , the reaction product is heated by the heat exchanger H 3 , and supplied into the catalyst tube C 2 as stable isotope labeled carbon dioxide selectively containing 13 C 18 O 18 O. On the other hand, an excessive amount of the hydrogen is supplied from the supply source 5 into the catalyst tube C 2 via the supply line L 4 and the like. Therefore, in the catalyst tube C 2 , the chemical reaction shown in the following formula (4) occurs.

13 C 18 O 18 O+H 2 → 13 C 18 O+H 2 18 O  Formula (4)

Next, in the method for producing stable isotope labeled carbon monoxide of the third embodiment, the stable isotope labeled carbon dioxide and hydrogen are mixed once more. Unreacted stable isotope labeled carbon dioxide, which is not reacted with hydrogen, is flowing through the connection line L 6 . The unreacted stable isotope labeled carbon dioxide passes through the connection line L 6 together with the reaction product, 13 C 18 O, of the chemical reaction shown in formula (4). The moisture is removed by the dehumidifier F 2 , the unreacted stable isotope labeled carbon dioxide and the reaction product are heated by the heat exchanger H 5 , and then supplied into the catalyst tube C 3 . On the other hand, an excessive amount of hydrogen is supplied into the catalyst tube C 3 from the supply source 5 through the supply line L 7 and the like. Therefore, in catalyst tube C 3 , the chemical reaction shown in equation (4) occurs one more time.

Thereafter, 13 C 18 O which is the reaction product of the chemical reaction shown in the formula (4) passes through the lead-out line L 8 . After removing moisture by the dehumidifier F 3 , the reaction product is led into a storage container (not shown).

(Effects)

In the third embodiment above, since the operation of mixing of the stable isotope labeled carbon dioxide and hydrogen is performed a plurality of times, it is possible to reliably react unreacted stable isotope labeled carbon dioxide which has not reacted with hydrogen in the chemical reaction shown in the first formula (4) with hydrogen. Therefore, according to the method for producing of stable isotope labeled carbon monoxide of the third embodiment, in addition to the same effects as those of the first embodiment can be obtained, the yield of the stable isotope labeled carbon monoxide, in which the abundance ratio of specific kind of stable oxygen isotope is controlled to be an arbitrary value, can be higher than that in the first embodiment.

Although several embodiments have been described above, the present invention is not limited to the specific embodiments. In addition, the present invention may be added, omitted, substituted, and other changes in composition within the scope of the present invention described in the claims.

For example, in the first embodiment and third embodiment above, the case in which the carbon monoxide selectively contains only 13 C 16 O and the water vapor selectively contains only H 2 18 O has been described as an example. However, the first embodiment and the third embodiment are not limited to this example. In other words, the carbon monoxide may selectively contain one kind of stable isotope other than 13 C 16 O, and may contain at least two or more kinds of stable isotopes. Similarly, the water vapor may selectively contain one kind of stable isotope other than H 2 18 O and may contain at least two or more kinds of stable isotopes.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited by the following examples. In the following examples, carbon monoxide includes stable isotope (C 17 O) having 17 O. However, the description of C 17 O may be omitted for the sake of simplicity.

The method for producing stable isotope labeled carbon monoxide and a method for producing stable isotope labeled carbon dioxide of the present invention can be applied to the industrial production of stable isotope-labeled gas.

1 , 2 producing apparatus

3 to 5 supply source

6 to 8 temperature control device

L 1 , L 2 , L 4 , and L 7 supply line

L 3 and L 6 connection line

L 5 and L 8 lead-out line

C 1 to C 3 catalyst tube

F 1 to F 3 dehumidifier

H 1 to H 6 heat exchanger

M 1 to M 3 flow regulator