JP6889644B2 - Oxygen isotope substitution method and oxygen isotope substitution device - Google Patents

Description

The present invention relates to an oxygen isotope substitution method for introducing an oxygen isotope into carbon monoxide and an oxygen isotope substitution apparatus.

Stable carbon isotopes ( ¹³ C) are mainly used as tracers in the fields of natural science and medicine. ^{There are two types of stable isotopes, 12} C and ¹³ C, in carbon, and the proportions of their presence in nature are 98.9% and 1.1%, respectively.
On the other hand, oxygen has ^{three types of stable isotopes, 16} O, ¹⁷ O and ¹⁸ O, and their presence rates in nature are 99.76%, 0.04% and 0.20%, respectively.
Therefore, there are six types of stable isotope molecules ^{in carbon monoxide: 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.}

Conventionally, as a method for synthesizing an oxygen isotope-labeled compound, for example, _{a method using H 2} ^{O containing the oxygen isotope 17} O or ¹⁸ O as a raw material has been adopted (see, for example, Patent Documents 1 and 2). ).
Further, when the oxygen isotope is separated by distillation, for example, a distillation apparatus having a scrambler is used (see, for example, Patent Documents 3 and 4).

Further, as a method for separating and concentrating isotopes that are present in a very small amount in nature as described above, a distillation cascade process in which a plurality of distillation columns are connected in series and used as disclosed in Patent Document 3 is generally used. Has been adopted. Further, Patent Document 3 describes that, as a method of distilling an oxygen isotope, when ¹⁷ O is concentrated and separated, ¹⁸ O is selectively impaired by a laser.

Here, _{a steam reforming method for CH 4} and other hydrocarbons, carbon, etc. is widely known as a method for producing hydrogen as a raw material for a fuel cell (see, for example, Patent Document 5).
On the other hand, the reaction by the steam reforming method often contains a large amount of carbon monoxide CO, but since CO is a compound that may cause a problem in the fuel cell, carbon monoxide CO and carbon dioxide Many proposals have been made conventionally for a method for removing CO by a methanation reaction (methanation) of CO _{2 (see, for example, Patent Document 6).}

Japanese Unexamined Patent Publication No. 2006-008591 Japanese Unexamined Patent Publication No. 2011-057557 Japanese Patent No. 5026974 Japanese Patent No. 4467190 Japanese Patent No. 5710964 Japanese Unexamined Patent Publication No. 2013-11149

Conventionally, among the carbon monoxide six stable isotopes molecules as described above exists, for example, for the purpose of obtaining a stable isotope molecule is ^{13 C} 16 ^O containing ^{13 C} in a large amount, ¹³ C ¹⁶ A method of concentrating O in the distillation column at the end of the distillation cascade process is employed. However, for example, ¹³ C ¹⁶ O and ¹² C ¹⁸ O have similar molecular weights and boiling points, and their concentration proceeds at the same time, so that it is difficult to efficiently and highly concentrate ¹³ C ^{16 O.} It was.

Further, in the carbon monoxide distillation process as described above, a distillation apparatus having a scrambler as described in Patent Documents 3 and 4 is used, or oxygen isotopes ¹⁷ O and ¹⁸ O are impaired. However, at present, a ^{method capable of efficiently degrading these 17} O and ¹⁸ O has not been established.

Further, conventionally, as a method for synthesizing an oxygen isotope-labeled compound, a method using _{H 2} O containing the ^{oxygen isotope 17} O or ¹⁸ O as described above as a raw material has been adopted, but the scale is industrially productive. No method has been proposed in which an arbitrary oxygen isotope can be efficiently introduced into a carbon monoxide CO containing carbon isotopes ¹² C or ^{13 C at an arbitrary ratio.}
That is, a method or apparatus for performing efficient oxygen isotope substitution in a large amount of carbon monoxide CO in a production line has not been proposed so far.

The present invention has been made in view of the above problems, and any oxygen isotope can be efficiently introduced into carbon monoxide CO containing ^{carbon isotopes 12} C and ^{13 C at an arbitrary ratio, which is desired.} It is an object of the present invention to provide an oxygen isotope substitution method and an oxygen isotope substitution apparatus capable of obtaining a stable carbon oxide isotope with high purity.

The present inventors have made extensive studies to solve the above problems. As a result, when carrying out an oxygen isotope substitution reaction in a stable carbon isotope containing ¹² C and ¹³ C, first, carbon monoxide CO is reduced by _{H 2} ^{to obtain either 12} C, ¹³ C or a hydrocarbon. After conversion to, it _{is reacted with H 2} ^{O containing oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O, and an arbitrary oxygen isotope is introduced and substituted to replace the oxygen isotope in carbon monoxide. The present invention has been completed by finding that the concentration of the body can be easily changed and the synthesis of a compound, which has been difficult to carry out on an industrially productive scale in the past, can be efficiently performed.

That is, the invention according to claim 1 is an oxygen isotope substitution method for introducing an arbitrary oxygen isotope into carbon monoxide, wherein carbon monoxide CO and H ₂ ^{containing at least carbon isotopes 12} C and ^{13 C are used.} preparative reacted in the first reactor, and ^{12 C,} 13 ^C or reduction reaction step of converting to any hydrocarbon, either of the ^{12 C} generated in the reduction reaction ^step, 13 ^C or hydrocarbons, _{By reacting H 2} O containing oxygen isotopes ¹⁶ O, ¹⁷ O and ¹⁸ O in the second reactor and introducing an arbitrary oxygen isotope, stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² Oxygen isotope substitution comprising an oxidation reaction step that selectively produces either C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ^{18 O.} The method.

The invention according to claim 2 is the oxygen isotope substitution method according to claim 1, further, dehydration treatment of the oxidation reaction gas after the reaction in the oxidation reaction step to H ₂ O which is a by-product. _{After removing the above, CO 2} which is a by-product is recovered by using an adsorber, and then a hydrocarbon which is an unreacted product in the oxidation reaction step and H which is a by-product are used by using a distillation tower. _It is an oxygen isotope substitution method characterized by having a purification step of purifying the stable carbon monoxide isotope produced in the oxidation reaction step with high purity by recovering 2.

The invention according to claim 3 is the oxygen isotope substitution method according to claim 2, further comprising the unreacted hydrocarbon and the by-product recovered in the purification step. It is an oxygen isotope substitution method characterized by having a return step of returning _{CO 2 to the reduction reaction step and subjecting it to a rereaction.}

The invention according to claim 4 is the oxygen isotope substitution method according to claim 2 or 3, and further, in the purification step, H ₂ recovered in the distillation column is returned to the adsorbent. , An oxygen isotope substitution method characterized by performing a regeneration process of the adsorbent.

The invention according to claim 5 is the oxygen isotope substitution method according to any one of claims 1 to 4, and further, the reduction is performed between the reduction reaction step and the oxidation reaction step. Oxygen isotope substitution characterized by providing a dehumidifying step of dehumidifying ¹² C, ¹³ C or hydrocarbons produced in the reaction step in a _{dehumidifier to remove H 2 O, which is a by-product.} The method.

The invention according to claim 6 is an oxygen isotope substitution device that introduces an arbitrary oxygen isotope into carbon monoxide, and comprises at least carbon monoxide CO and H ₂ ^{containing carbon isotopes 12} C and ^{13 C. An oxygen isotope 16} with a first reactor that reacts internally ^{and converts to either 12} C, ¹³ C or a hydrocarbon, and any of the ¹² C, ¹³ C or hydrocarbons produced by the first reactor. _{By internally reacting with H 2} O including O, ¹⁷ O and ¹⁸ O and introducing an arbitrary oxygen isotope, stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O , ¹³ C ¹⁶ O, ¹³ C ¹⁷ O, or ¹³ C ¹⁸ O, which is an oxygen isotope substitution apparatus.

The invention according to claim 7 is the oxygen isotope substitution apparatus according to claim 6, further, dehydration treatment of the oxidation reaction gas after the reaction in the second reactor, and H ₂ O which is a by-product. A dehydrator for removing the _{above, an adsorber for adsorbing and recovering CO 2} which is a by-product, a hydrocarbon which is an unreacted product in the second reactor, and H ₂ which is a by-product are recovered. This is an oxygen isotope substitution apparatus including a distillation column for purifying the stable carbon monoxide isotope produced in the second reactor with high purity.

The invention according to claim 8 is the oxygen isotope substitution apparatus according to claim 7, and further, CO ₂ which is the by-product recovered by the adsorber and CO 2 recovered by the distillation column. The oxygen isotope substitution apparatus is provided with a return unit for returning the unreacted hydrocarbon to the first reactor.

The invention according to claim 9 is the oxygen isotopic substitution apparatus according to claim 7 or claim 8, further return of H ₂ recovered in the distillation column in the adsorber, the adsorber vessel It is an oxygen isotope substitution apparatus characterized by including an adsorber regeneration processing unit for performing regeneration processing.

The invention according to claim 10 is the oxygen isotope substitution device according to any one of claims 6 to 9, further, between the first reactor and the second reactor. Oxygen is provided with a dehumidifier that dehumidifies ¹² C, ¹³ C or hydrocarbons produced in the first reactor in a dehumidifier to remove _{H 2 O, which is a by-product.} It is an isotope substitution device.

According to the oxygen isotope substitution method according to the present invention, at least carbon monoxide CO containing ^{carbon isotopes 12} C and ¹³ C is reacted _{with H 2} to be converted into either ¹² C, ^{13 C or hydrocarbon.} By reacting ^{any of 12} C, ¹³ C or hydrocarbon with H ₂ ^{O containing oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O and introducing an arbitrary oxygen isotope, An oxidation reaction step that selectively produces any of the stable carbon oxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O, or ¹³ C ^{18 O.} The configuration with is adopted.
According to the present invention, by sequentially providing the reduction reaction step and the oxidation reaction step as described above, an arbitrary oxygen isotope can be efficiently introduced into the carbon monoxide CO at an arbitrary ratio. Therefore, a high-purity carbon monoxide stable isotope having a desired oxygen isotope can be efficiently obtained on an industrially productive scale at low cost.

Further, according to the oxygen isotope substitution apparatus according to the present invention, at least carbon monoxide CO containing ^{carbon isotopes 12} C and ¹³ C is reacted _{with H 2} ^{to be either 12} C, ¹³ C or a hydrocarbon. The first reactor that converts to is reacted with ^{any of 12} C, ¹³ C or hydrocarbons and H ₂ ^{O containing oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O to introduce any oxygen isotope. Second, selectively produces any of the stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ^{18 O.} A configuration equipped with a reactor is adopted.
According to the present invention, by adopting a configuration in which a first reactor that performs a reduction reaction and a second reactor that performs an oxidation reaction are sequentially provided, a high-purity one having a desired oxygen isotope as described above. It will be possible to obtain stable carbon oxide isotopes efficiently at low cost on an industrially productive scale.

It is a figure which schematically explains the oxygen isotope substitution method which is one Embodiment of this invention, and is the schematic which shows the flow path between steps in a simplified manner. It is a figure which shows typically the oxygen isotope substitution method and oxygen isotope substitution apparatus which are one Embodiment of this invention, and is the schematic diagram which shows the apparatus structure and each flow path in detail.

Hereinafter, the oxygen isotope substitution method and the oxygen isotope substitution apparatus according to the embodiment to which the present invention is applied will be described with reference to FIGS. 1 and 2 as appropriate. In addition, in the drawing used in the following description, in order to make the feature easy to understand, the feature portion may be enlarged or simplified for convenience. Further, the materials and the like exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

The oxygen isotope substitution method and the oxygen isotope substitution apparatus according to the present invention are methods and apparatus for introducing an arbitrary oxygen isotope into carbon monoxide, and for example, by an oxygen isotope substitution apparatus as exemplified below. On an industrially productive scale, any oxygen isotope ¹⁶ O, ¹⁷ O or ¹⁸ O is introduced into the ^{carbon monoxide CO containing the carbon isotopes 12} C and ^{13 C at any ratio.}

In the present invention, when performing an oxygen isotope substitution reaction in a stable carbon monoxide isotope containing ¹² C and ¹³ C, first, carbon monoxide CO containing ^{carbon isotopes 12} C and ¹³ C is reacted _{with H 2.} Then, a reduction reaction is carried out to convert the mixture into either ¹² C, ^{13 C or a hydrocarbon. Then, by reacting any of 12} C, ¹³ C or hydrocarbon produced in the reduction reaction with _{H 2} ^{O containing oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O, and introducing an arbitrary oxygen isotope. , Carbon monoxide stable isotope ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ O. Do. In the present invention, the concentration of the oxygen isotope can be easily and efficiently changed by introducing and substituting the oxygen isotope into carbon monoxide by such a method.

<Oxygen isotope replacement device>
An example of an oxygen isotope substitution device that can be used for oxygen isotope substitution in the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram showing a simplified flow path between steps in the present embodiment, and FIG. 2 is a diagram for explaining an apparatus configuration and each flow path in more detail.

The oxygen isotope substitution apparatus 10 of the present embodiment introduces an arbitrary oxygen isotope into carbon monoxide, and specifically, at least carbon monoxide CO containing a carbon isotope and H ₂ are internally contained. in ^reacted, 12 ^{C, 13} a first reactor 1A to be converted to either the C or hydrocarbons, one oxygen isotopes of the first ¹² C generated in the reactor ^{1A, 13} C or hydrocarbons It is provided with a second reactor 1B that selectively produces a stable carbon monoxide isotope by reacting with the contained H _{2 O and introducing and substituting an arbitrary oxygen isotope.}

Further, in the oxygen isotope substitution apparatus 10 of the illustrated example, in addition to the above-mentioned first reactor 1A and second reactor 1B, the reaction gas after the oxidation reaction in the second reactor 1B is further dehydrated to H ₂ Stable carbon monoxide produced in the second reactor 1B by recovering the dehydrator 2 that removes O, the adsorber 3 that adsorbs and recovers _{CO 2} , and hydrocarbons such as _{CH 4 and H 2.} It is provided with a distillation column 4 for purifying isotopes with high purity, CO ₂ recovered by the adsorber 3, and a return section 5 for returning the hydrocarbon recovered by the distillation column 4 to the reactor 1. Will be done. Further, in the oxygen isotope substitution device 10 of the illustrated example, a dehumidifier 7 is further provided between the first reactor 1A and the second reactor 1B.

The first reactor 1A internally reacts carbon monoxide CO containing ^{carbon isotopes 12} C and ¹³ _{C with H 2} ^{to convert it into either 12} C, ¹³ C or a hydrocarbon, which is a reaction formula described later. It causes an oxidation reaction as shown in. As shown in FIG. 2, a raw material supply line L1 is connected to the inlet side of the first reactor 1A, and carbon monoxide CO containing ^{carbon isotopes 12} C and ^{13 C is supplied.} Moreover, the path of the material supply line L1, is connected to the hydrogen supply line L2, the first reactor 1A, via a material supply line L1, and is configured so that it can supply of H ₂ with CO.

Here, the hydrocarbon obtained in the first reactor 1A in the present embodiment includes various hydrocarbons represented by _{C n} H _{2n + 1} in addition to _{CH 4.}

In order to cause the above reduction reaction in the first reactor 1A, it is also possible to put _{H 2 in the inside of the first reactor 1A in advance.}

In the oxygen isotope substitution device 10 of the illustrated example, the dehumidifier 7 is connected to the rear side of the first reactor 1A via the connection line L3. ^{The dehumidifier 7 is a device that dehumidifies 12} C, ¹³ C or hydrocarbons obtained by an oxidation reaction in the first reactor 1A _{to remove H 2} O, which is a by-product, to a certain extent, for example. Various dehumidifying devices such as a constant humidity and constant temperature bath that adjusts temperature and humidity can be used.

^{The second reactor 1B contains either 12} C, ¹³ C or a hydrocarbon obtained by an oxidation reaction in the first reactor 1A and H ₂ O ^{containing oxygen isotopes 16} O, ¹⁷ O and ^{18 O.} React internally. The second reactor 1B of the illustrated example has a connection line L5 connected to the inlet side and is connected to the first reactor 1A via the dehumidifier 7 described above. Further, a water supply line L6 is connected to the path of the connection line L5, _{and H 2} O ^{containing oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O is transmitted to the second reactor 1B via the connection line L5. It is configured to be able to supply.

The second reactor 1B causes the above-mentioned oxidation reaction, and the oxygen isotopes ¹⁶ O and ¹⁷ O ^{are added to the 12} C, ^{13 C or the hydrocarbon introduced from the first reactor 1A via the dehumidifier 7.} Alternatively ^{, any oxygen isotope of 18} O is introduced (oxidation reaction). As a result, the second reactor 1B is one of the carbon monoxide stable isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ O. Is selectively generated, and in addition to these, a reaction gas containing various by-products and unreacted products is generated.

The dehydrator 2 dehydrates the reaction gas after the oxidation reaction in the second reactor 1B to remove _{H 2 O, which is a by-product.} As shown in FIG. 2, the inlet of the dehydrator 2 is connected to the outlet side of the second reactor 1B via the connection line L7, and the reaction gas is introduced from the second reactor 1B. .. In addition, the dehydrator 2, the drain line L9 for discharging of H _{2 O} was removed from the reaction gas to the outside are connected by a dehydration process.

The dehydrator 2 is not particularly limited, and for example, a conventionally known chiller (water-cooled type or air-cooled type) can be used without any limitation. The dehydrator 2 is by its cooling effect, it is possible to remove the H _{2 O} contained in the reaction gas to a certain degree.

The adsorber 3 adsorbs and recovers _{CO 2} produced as a by-product in the oxidation reaction generated in the second reactor 1B. The adsorber 3 of the example shown in FIG. 2 is a _{first adsorber 31 into which a reaction gas from which H 2} O has been removed to a certain degree is introduced in the dehydrator 2, and a second adsorber 32 arranged on the subsequent stage side. It is composed of and. Further, in the adsorber 3 of the illustrated example, the inlet side of the first adsorber 31 is connected to the outlet side of the dehydrator 2 via the connection line L8, and the reaction gas dehydrated by the dehydrator 2 is introduced. , The inlet side of the second adsorber 32 is connected to the outlet side of the first adsorber 31 via the connection line L10.

In the adsorber 3 of the present embodiment, first, the reaction gas is further sufficiently dehydrated in the first adsorber 31, and CO ₂ is adsorbed and recovered in the second adsorber 32. Has been done.
As the first adsorber 31 and the second adsorber 32, conventionally known adsorption equipment can be adopted without any limitation.

The distillation column 4 is generated in the second reactor 1B by recovering _{hydrocarbons such as CH 4 which are unreacted substances and H 2} which is a by-product in the oxidation reaction generated in the second reactor 1B. The stable carbon monoxide isotope is purified to a high degree of purity. As shown in FIG. 2, the distillation column 4 has a configuration in which a plurality of distillation columns are cascaded in series, and in the illustrated example, _{a reaction gas from which H 2} O and CO ₂ introduced from the adsorber 3 have been removed. It is composed of a first distillation column 41 into which the carbon dioxide is introduced and a second distillation column 42 arranged on the subsequent stage side.

The inlet side of the first distillation column 41 is connected to the outlet side of the second adsorber 32 via the connection line L11. Then, the first distillation column 41 recovers _{H 2} , which is a by-product of the above-mentioned oxidation reaction, by distilling the reaction gas introduced from the adsorber 3 from which H ₂ O and CO _{2 have been removed.} To do.

The inlet side of the second distillation column 42 is connected to the outlet side of the first distillation column 41 via a connection line L12. Then, the second distillation column 42 further recovers hydrocarbons such as _{CH 4} by distilling the reaction gas in which _{H 2 is recovered in the first distillation column 41.}

Here, although detailed illustration is omitted, the connection line L11 is connected to, for example, the vicinity of the central portion in the height direction of the first distillation column 41. Further, for example, the inlet side of the connection line L12 is connected to an arbitrary position in the height direction of the first distillation column 41, and the outlet side is connected to the vicinity of the central portion in the height direction of the second distillation column 42. The "middle portion in the height direction of the distillation column" described in the present embodiment means a position other than the top and bottom of the first distillation column 41 and the second distillation column 42.

Although detailed illustration of the first distillation column 41 and the second distillation column 42 is omitted, carbon monoxide CO contained in the reaction gas is distilled at a low temperature (distillation cascade process) so that the carbon monoxide CO can be placed on the top side of each column. , Carbon monoxide isotope molecules with a low boiling point ( ¹² C ¹⁶ O, etc.) are concentrated, and carbon monoxide isotope molecules with a high boiling point (for example, ¹³ C ¹⁶ O, ¹² C ¹⁸ O and ¹³ C ^{18) are concentrated on the bottom side of the column.} It is configured so that O) can be concentrated.

Further, for example, ^{in the case of purifying 13} C ¹⁶ O as a carbon monoxide isotope, the distillation column 3 (first distillation column 41 and second distillation column 42) can be made larger in size so as to be on the bottom side of the column. , ¹³ C ¹⁶ O can be purified with higher purity.

Further, in general, of the first distillation column 41 and the second distillation column 42, the first distillation column 41 on the upstream side has a large distillation load, and the second distillation column 42 on the downstream side has a first distillation column 41. The distillation load is smaller than that. Therefore, the second distillation column 42 can be configured to have a smaller diameter than the first distillation column 41.

The inside of the first distillation column 41 and the second distillation column 42 are provided with a rectification stage (shelf), a regular filler, an irregular filler, and the like, which are not shown, respectively.

Further, although not shown in FIG. 2, the first distillation column 41 and the second distillation column 42 are vaporized by heat exchange of the liquid descending in each distillation column, and each distillation is performed again. A configuration equipped with a reboiler for raising the inside of the tower can be adopted. Further, each of the first distillation column 41 and the second distillation column 42 is provided with a capacitor for liquefying the rising gas in each distillation column by heat exchange and lowering the inside of each distillation column again. Can be adopted.

In the oxygen isotope substitution apparatus 10 of the present embodiment, the dehydrator 2, the adsorber 3, and the distillation tower 4 are provided, so that the by-products contained in the reaction gas undergoing the oxidation reaction in the second reactor 1B are provided. And selectively produced carbon monoxide stable isotopes ( ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ O) by removing unreacted substances. At least one of these) can be purified to a high degree of purity.

The carbon monoxide stable isotope produced in the second distillation column 42 with high purity is delivered from the final line L13 toward, for example, a product cylinder.
The "highly pure" carbon monoxide stable isotope described in the present invention means that the total concentration of the carbon monoxide stable isotope is 99.9% or more.

_{The return unit 5 returns CO 2} , which is a by-product recovered in the adsorber 3, and hydrocarbon, which is an unreacted product recovered in the distillation column 4, to the first reactor 1A. As shown in FIG. 2, the return unit 5 returns the hydrocarbon removed by the second distillation column 42 to the raw material supply line L1 communicated with the first reactor 1A via the return line 52 described later. It is composed of a first return line 51 and a _{second return line 52 that returns CO 2} removed by the second adsorber 32 to the raw material supply line L1.

In the oxygen isotope substitution apparatus 10 of the present embodiment, the above-mentioned unreacted products ( _{hydrocarbons such as CH 4} ) and by-products (H ₂ and CO ₂ ) are returned to the first reactor 1A again as a raw material. The effect of improving the yield of the desired stable carbon monoxide isotope can be obtained.

In the oxygen isotope substitution apparatus 10 of the present embodiment, as shown in FIG. 2, in addition to the above configurations, H ₂ recovered in the distillation column 4 (first distillation column 41) is further adsorbed. It is more preferable to include an adsorber regeneration processing unit 6 that returns to the vessel 3 (second adsorber 32) and _{regenerates the second adsorber 32 by the H 2.} As shown in the schematic diagram of FIG. 2, the adsorber regeneration processing unit 6 connects the first distillation column 41 and the second adsorber 32, and is composed of a pipe different from the connection line L11 described above. There is.

Since the oxygen isotope substitution device 10 includes the above-mentioned adsorber regeneration processing unit 6, the regeneration processing of the second adsorber 31 can be performed regularly or irregularly, so that the second adsorber 31 can be regenerated. The adsorption performance can be maintained at all times, and CO ₂ can be removed efficiently and reliably. Further, since the adsorber regeneration processing unit 6 _{reuses H 2} removed from the reaction gas, the second adsorber 31 can be regenerated at low cost, and the oxygen isotope replacement device 10 can be used. It becomes possible to further increase the purity of the obtained stable carbon monoxide isotope.

<Oxygen isotope substitution method>
The oxygen isotope substitution method of the present embodiment is a method of introducing an arbitrary oxygen isotope into carbon monoxide. Hereinafter, the oxygen isotope substitution method of the present embodiment will be described in detail with reference to a case where substitution is performed using the oxygen isotope substitution apparatus 10 of the present embodiment as shown in FIG.

In the oxygen isotope substitution method of the present embodiment, at least carbon monoxide CO containing ^{carbon isotopes 12} C and ¹³ _{C and H 2} are reacted in the first reactor 1A, and ¹² C, ¹³ C or hydrocarbons are reacted. The reduction reaction step of converting to any of the above, any of the ¹² C, ¹³ C or hydrocarbons _{produced in the reduction reaction step, and H 2} ^{O containing the oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O are second. By reacting in the reactor 1B and introducing an arbitrary oxygen isotope, carbon monoxide stable isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or A method comprising an oxidation reaction step of selectively producing any of ¹³ C ^{18 O (see FIG. 1).}

Further, in the present embodiment, following the above-mentioned reduction reaction step and oxidation reaction step, the reaction gas after the oxidation reaction is further dehydrated to remove _{H 2 O, and then CO 2} is recovered, and then CH. A method having a purification step of purifying a stable carbon monoxide isotope with high purity by recovering a hydrocarbon such as _{4 and H 2 will be described as an example.} Further, in the example described in the present embodiment, there is a _{return step of returning the unreacted hydrocarbon and the by-product CO 2} recovered in the purification step to the reaction step for re-reaction. doing. Furthermore, in this embodiment, between the above reduction reaction step and the oxidation reaction process, an example of the dehumidifying process provided for removing of H _{2 O} as a by-product in the reduction reaction step.
Hereinafter, each step will be described.

(1) Reduction reaction step First, in the reduction reaction step, carbon monoxide CO containing ^{carbon isotopes 12} C and ¹³ _{C and H 2} are reacted in the first reactor 1A, and ¹² C, ¹³ C or hydrocarbons are reacted. Convert to one of. At this time, ^{carbon monoxide CO containing carbon isotopes 12} C and ¹³ C is supplied from the raw material supply line L1, and H ₂ is supplied from the hydrogen supply line L2 via the raw material supply line L1.

As described above, by supplying each raw material to the first reactor 1A, as an example, the reduction reaction as shown in the following equations (1) and (2) proceeds, and C ( ¹² C or ¹³ C). Is obtained. _{That is, for example, by mixing CO and H 2} in the presence of an iron-based catalyst and heating them, ¹² C or ¹³ C is obtained, and H ₂ O, which is a by-product, is produced.
¹² C ¹⁸ O + H ₂ → ¹² C + H ₂ ¹⁸ O ・ ・ ・ ・ ・ (1)
¹³ C ¹⁸ O + H ₂ → ¹³ C + H ₂ ¹⁸ O ・ ・ ・ ・ ・ (2)

Further, in the reduction reaction step, the reduction reaction as shown in the following equations (3) and (4) proceeds, and CH ₄ ( ¹² CH ₄ or ¹³ CH ₄ ) is obtained. ^{That is, 12} CH ₄ or ¹³ CH ₄ is obtained by a so-called meta-nation reaction known as a catalytic reaction carried out to remove a small amount of CO generated in the hydrogen production process.
¹² C ¹⁸ O + 3H ₂ → ¹² CH ₄ + H ₂ ¹⁸ O ・ ・ ・ ・ ・ (3)
¹³ C ¹⁸ O + 3H ₂ → ¹³ CH ₄ + H ₂ ¹⁸ O ・ ・ ・ ・ ・ (4)

Further, in the reduction reaction step, although detailed reaction formulas are omitted, CO and H ₂ are reacted in the presence of a catalyst such as iron or cobalt, which is a so-called Fischer-Tropsch method (FT method) other than _{CH 4.} Cobalt is obtained.

In the reduction reaction step, it is preferable to cause the reduction reaction in the temperature range of 200 to 1200 ° C. in the first reactor 1A. By setting the temperature in the first reactor 1A within the above range, the above reduction reaction proceeds more effectively, and it becomes possible to efficiently generate either ¹² C, ^{13 C or a hydrocarbon.} .. Further, from the above viewpoint, the temperature in the first reactor 11A is more preferably 700 to 900 ° C.

If the temperature in the first reactor 1A is less than the lower limit of the above range, it may be difficult to effectively cause a reduction reaction. On the other hand, even if the temperature in the first reactor 1A exceeds the upper limit of the above range, the above-mentioned effect may be saturated and the energy used for heating the first reactor 1A may be wasted.

In the reduction reaction step, in order to cause the above reduction reaction in the first reactor 1A, it is also possible to _{preliminarily contain H 2 in the first reactor 1A as described above.} Is.

(2) Dehumidifying step Next, in the dehumidifying step, ¹² C, ¹³ C or hydrocarbons produced in the reduction reaction step are dehumidified in the dehumidifier 7 to remove water (H ₂ O) to a certain extent. .. Then, the removed H ₂ O is sent to the outside from the drainage line L4 connected to the dehumidifier 7.

(3) Oxidation reaction step Next, in the oxidation reaction step, H ₂ O ^{containing either 12} C, ¹³ C or hydrocarbon ^{produced in the reduction reaction step and oxygen isotopes 16} O, ¹⁷ O and ^{18 O.} Is reacted in the second reactor 1B to cause an oxidation reaction. At this time, the dehumidified ¹² C, ¹³ C or hydrocarbon is supplied from the connection line L5 to the second reactor 1B, and the oxygen isotopes ¹⁶ O and ^{17 are supplied from the water supply line L6 via the connection line L5.} H ₂ O containing O and ¹⁸ O is supplied. Here, in order to effectively introduce the oxygen isotope contained _{in H 2} O into carbon monoxide CO, it is preferable to supply a large amount of _{this H 2 O.} Thus, as a measure of the mass supplying H _{2 O} amount, for example, a volume ratio to the feed amount of carbon monoxide CO, may be in the range of about 10 to 30 times, in particular, carbon monoxide CO When introducing the oxygen isotope ¹⁷ O or ¹⁸ O, it is more preferable to supply as much _{H 2 O as possible.}

As described above, by causing an oxidation reaction in the second reactor 1B ^{and introducing an arbitrary oxygen isotope into either 12} C, ¹³ C or a hydrocarbon, the stable carbon monoxide isotope ¹² C ¹⁶ Either O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ O is selectively generated.

As an example, when the oxygen isotope ^{16 O is introduced into 12} C or ¹³ C, the reactions as shown in the following equations (5) and (6) first proceed in the second reactor 1B to carry out CO. Is generated.
¹² C + H ₂ ¹⁶ O → ¹² C ¹⁶ O + H ₂ ... (5)
¹³ C + H ₂ ¹⁶ O → ¹³ C ¹⁶ O + H ₂ ... (6)

Further, when the oxygen isotope ¹⁶ O is introduced into a hydrocarbon, for example, CH ₄ ( ¹² CH ₄ or ¹³ CH ₄ ), the following equations (7) and (8) are shown in the second reactor 1B. Oxidation reaction occurs.
¹² CH ₄ + H ₂ ¹⁶ O → ¹² C ¹⁶ O + 3H ₂ ... (7)
¹³ CH ₄ + H ₂ ¹⁶ O → ¹³ C ¹⁶ O + 3H ₂ ... (8)

The reaction between hydrocarbons such as CH _{4 and H 2} O as described above is based on a steam reforming method in which high-temperature steam (H _{2 O) reacts with carbides in the presence of a catalyst, and is coke.} , A method generally used when obtaining hydrogen from natural gas, petroleum, etc.

(5) to (8) that the oxidation reaction occurs as shown in the expression, the reaction between oxygen and ¹² C or ¹³ C in _{H 2} O, or carbide of ₄ such as oxygen and CH in _{H 2} O ^{Any oxygen isotope (16} O in the examples represented by the above formulas) can be introduced by the exchange reaction with hydrogen in hydrogen. By such an oxidation reaction, ^{the concentration of oxygen isotopes in the stable carbon monoxide isotopes including 12} C and ¹³ C can be easily and efficiently changed, and the stable carbon monoxide isotopes ( ^{13 in the examples of the above reaction formulas).} C ^{16 O)} it is possible to selectively produce. Further, as shown in the above equations (5) to (8), in particular, _{by supplying H 2} O having a high natural abundance ratio of the ^{oxygen isotope 16} O, the stable carbon monoxide isotope ¹³ C ^{containing 16 O is supplied. It is possible to generate 16} O and the like more efficiently and selectively.

In the oxidation reaction step, it is preferable to cause the oxidation reaction in the temperature range of 200 to 1200 ° C. in the second reactor 1B. By setting the temperature in the second reactor 1B within the above range, it becomes easy to introduce an arbitrary oxygen isotope into carbon monoxide, and a desired stable carbon monoxide isotope can be obtained more efficiently. Will be possible.
Further, from the above viewpoint, the temperature in the second reactor 1B is more preferably 800 to 1000 ° C.

If the temperature in the second reactor 1B is less than the lower limit of the above range, it may be difficult to effectively cause an oxidation reaction. On the other hand, even if the temperature inside the second reactor 1B exceeds the upper limit of the above range, the above-mentioned effect may be saturated and the energy used for heating the second reactor 1B may be wasted.

Further, in the oxidation reaction step, as in the case of the reaction formulas shown in the above formulas (5) to (8), for example, ^{oxygen isotope 17} O or ^{18 in any of 12} C, ¹³ C or hydrocarbon. By introducing O, either ¹² C ¹⁷ O or ¹³ C ^{17 O, or 12} C ¹⁸ O or ¹³ C ¹⁸ O can be selectively generated.
That is, in the reaction step in the oxygen isotope substitution method of the present embodiment, the stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ It is possible to selectively generate any one of O.

(4) Purification step Next, in the purification step, the reaction gas after the oxidation reaction in the above oxidation reaction step, that is, the stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ The ^{reaction gas containing either C 16} O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ _{O is dehydrated by the dehydrator 2 to remove H 2} O, which is a by-product generated in the oxidation reaction step, to a certain extent. To do.

Then, in the purification step, by using the first adsorber 31, further subjected to sufficient dehydration to the reaction gases, it is removed as much as possible H 2 _O.
Then, the second adsorber 32 is used to recover _{CO 2 which is a by-product.}

_{Next, in the purification step, the reaction gas from which H 2} O and CO ₂ have been removed is distilled by using the first distillation column 41 to recover _{H 2} , which is a by-product.
Next, the second distillation column 42 is used to distill the reaction gas in which _{H 2} is recovered in the first distillation column 41 to further recover hydrocarbons such as _{CH 4 which are unreacted products.}
Here, in the purification step of the present embodiment, the stable carbon monoxide isotope produced in the second reactor 1B is purified to high purity in the first distillation column 41 and the second distillation column. At this time, for example, immediately after the start of the purification process (immediately after the start of the first distillation column 41 and the second distillation column 42), the concentration of each stable carbon monoxide isotope is substantially uniform in each distillation column. .. Then, as the process time elapses, stable carbon monoxide isotopes with relatively high boiling points, especially ¹³ C ¹⁶ O, ¹² C ¹⁸ O and ¹³ C ¹⁸ O, are present in the first distillation column 41 and the second distillation column 42. Concentrated on the bottom side. Therefore, highly purified ¹³ C ¹⁶ O, ¹² C ¹⁸ O or ¹³ C ¹⁸ O can be taken out from the bottom side of the second distillation column 42, while it can be taken out from the top side of the second distillation column 42. ^{Can take out 12} C ¹⁶ O or the like having a relatively low boiling point in a state of being purified with high purity.

Then, in the purification step, the highly pure carbon monoxide stable isotope is delivered from the final line L13 connected to the second distillation column 42, for example, toward a product cylinder or the like.

In the purification step, in addition to each of the above treatments, H ₂ recovered in the first distillation column 41 is returned to the adsorber 3, specifically, the second adsorber 32, and the H ₂ is used. The second adsorber 32 may be regenerated.

(5) Return step Next, in the return step, the unreacted hydrocarbon and the by-product CO ₂ recovered in the purification step are returned to the reduction reaction step for re-reaction.
As described above, in the oxygen isotope substitution method of the present embodiment, the unreacted product ( _{hydrocarbon such as CH 4} ) and the by-product (H ₂ and CO ₂ ) in the reaction step are again reduced in the reduction reaction step (first). Returning to the reactor 1A) improves the yield of the desired stable carbon monoxide with respect to the raw material.

According to the oxygen isotope substitution method of the present embodiment, as a product containing a stable carbon monoxide isotope ^{, each of the oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O in CO has an arbitrary isotope concentration. It becomes possible to provide a compound. This makes it possible to obtain isotope-labeled compounds that were difficult to synthesize by conventional methods, for example, by introducing oxygen isotopes selectively and efficiently for alcohol, aldehyde, and ester bonds. Become.

As described ^{above, 13} in performing distillation (purification step) for CO separation including the C, there is a carbon isotope of ¹² C and ¹³ C is and C, also the O oxygen isotope ^{16 O, 17} O and ¹⁸ O are present, from the natural abundance ^ratio, mostly ¹³ C ¹⁶ O (molecular weight: 29) of the CO containing ¹³ C is. On the other hand, in the conventional method, as the concentration by distillation progresses, ¹² C ¹⁷ O (molecular weight: 29), ¹² C ¹⁸ O (molecular weight: 30), ¹³ C ¹⁷ O (molecular weight: 30) and ¹³ C ¹⁸ O (molecular weight: 30). : 31) could not be concentrated at a sufficiently high concentration ^{because the concentration of 13} ) proceeded at the same time. On the other hand, in the present embodiment, ^{CO containing 13} C can be efficiently concentrated by adjusting O to be replaced with a single oxygen isotope.

<Other forms>
Although an example of the oxygen isotope substitution method and the oxygen isotope substitution apparatus according to the present invention has been described above according to the embodiment, the present invention is not limited to the above embodiment. Each configuration and a combination thereof in the above-described embodiment are examples, and the configuration can be added, omitted, replaced, and other changes are possible without departing from the spirit of the present invention.
For example, in the present embodiment, an example in which the distillation column 3 is provided with two units of the first distillation column 41 and the second distillation column 42 is described, but the present invention is not limited to this, and an arbitrary number of units is set. It is possible.

<Effect>
As described above, according to the oxygen isotope substitution method of the present embodiment, carbon monoxide CO containing ^{at least carbon isotopes 12} C and ¹³ C is reacted _{with H 2} ^{to 12} C, ¹³ C or carbonized. A reduction reaction step to convert to any of hydrogen and any of ¹² C, ¹³ C or hydrocarbons reacted with H ₂ ^{O containing oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O to produce any oxygen isotope. By introduction, one of the stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ O is selectively produced. It employs a configuration having an oxidation reaction step of causing the carbonation. By adopting such a configuration in which the reduction reaction step and the oxidation reaction step are sequentially provided, an arbitrary oxygen isotope can be efficiently introduced into the carbon monoxide CO at an arbitrary ratio. Therefore, a high-purity carbon monoxide stable isotope having a desired oxygen isotope can be efficiently obtained on an industrially productive scale at low cost.

Further, in the oxygen isotope substitution method of the present embodiment, by further providing the above-mentioned purification step, the mixed gas containing the stable carbon monoxide isotope can be efficiently separated and purified, and the desired stable carbon monoxide isotope can be separated and purified. It is possible to obtain the body with high purity.
Further, by providing the above-mentioned return step, an efficient equilibrium reaction can be generated without wasting the raw material, and a high-purity carbon monoxide stable isotope can be obtained at low cost.

Next, according to the oxygen isotope substitution apparatus 10 of the present embodiment, carbon monoxide CO containing ^{at least carbon isotopes 12} C and ¹³ C is reacted _{with H 2} ^{to produce 12} C, ¹³ C or hydrocarbon. The first reactor 1A that converts to either is reacted with any of ¹² C, ¹³ C or hydrocarbons and H ₂ ^{O containing oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O to produce any oxygen isotope. By introduction, one of the stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ O is selectively produced. A configuration is adopted in which the second reactor 1B and the second reactor 1B are provided. As described above, by adopting a configuration in which the first reactor 1A for performing the reduction reaction and the second reactor 1B for performing the oxidation reaction are sequentially provided, a high-purity one having a desired oxygen isotope as described above is adopted. It will be possible to obtain stable carbon oxide isotopes efficiently at low cost on an industrially productive scale.

Further, in the oxygen isotope substitution device 10 of the present embodiment, a desired configuration including the above-mentioned dehydrator 2, adsorber 3, distillation column 4, return unit 5 and dehumidifier 7 is further adopted. High-purity carbon monoxide stable isotopes with oxygen isotopes can be efficiently obtained on an industrially productive scale at a lower cost.

Oxygen isotopic substitution method and the oxygen isotopic substitution device monoxide carbon isotope obtained in 10 of the present embodiment, in particular, carbon monoxide stable isotope ^{13 C} 16 ^O comprising the carbon isotope ^{13 C} in a high concentration, For example, it is extremely useful as a tracer in the medical field and the like.

Hereinafter, the oxygen isotope substitution method and the oxygen isotope substitution apparatus of the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples, and the gist thereof is changed. It can be changed as appropriate to the extent that it does not.

In the present embodiment, by using the oxygen isotopic substitution apparatus 10 as shown in FIG. 2, was synthesized (reaction) - Purification of carbon monoxide isotope ^{13 C} 16 ^O under the conditions and procedures given below. Further, at this time, the flow rate, concentration, and concentration ratio of the gas in each of the flow paths (A) to (R) in the oxygen isotope substitution apparatus 10 shown in FIG. 2 are shown in Table 1 below.

First, the oxygen isotope substitution device 10 is started, and the carbon monoxide CO containing the ^{carbon isotope 13 C is started from the separately prepared 13} C concentration distillation tower toward the first reactor 1A via the raw material supply line L1. (1 Nm ³ / h, ¹⁶ O: 85.8%, ¹⁷ O: 0.645%, ¹⁸ O: 13.5%) was supplied (see FIG. 2 and (A) shown in Table 1 below). _{At the same time, H 2} (5.0 Nm ³ / h) was mixed from the hydrogen supply line L2 via the raw material supply line L1. Furthermore, pre-treated regeneration gas in the second distillation column _{^{42 (5.44Nm 3 /h,CO:0.28%,H 2: 91.86}} %, CH 4: 2.53%, H 2 O: 0 .00%, CO ₂ : 5.33%) was mixed via the raw material supply line L1 and introduced into the first reactor 1A under the condition of 800 ° C. and 5 atm (in FIG. 2 and Table 1 below). (Q) and (B) shown). When the flow rate of hydrogen in the regenerated gas pretreated in the second distillation column 42 reached 5.0 Nm ³ / h, the supply of hydrogen from the hydrogen supply line L2 was stopped.

At this time, the first reactor 1A is pre-filled with a catalyst containing Ni as a main component, and the first reactor 1A is shown in the following equations (2) and (4). A reduction reaction was carried out to obtain a gas containing ¹³ C and CH _{4 (hydrocarbon).}
¹³ C ¹⁸ O + H ₂ → ¹³ C + H ₂ ¹⁸ O ・ ・ ・ ・ ・ (2)
¹³ C ¹⁸ O + 3H ₂ → ¹³ CH ₄ + H ₂ ¹⁸ O ・ ・ ・ ・ ・ (4)

Then, the reduction reaction gas after the reaction in the first reactor _{^{1A (3.96Nm 3 /h,CO:1.28%,H 2: 25.34}} %, CH 4: 34.77%, H 2 O: 38 .25%, CO _2: after 0.37%) was cooled to 10 ° C., subjected to dehumidification process by introducing to the dehumidifier 7, to remove the _{H 2} O.

_{Next, steam (H 2} O, 30 Nm ³ / h, ¹⁶ O: 99.8%, ¹⁷ O: 0.038%, ¹⁸⁾ from the water supply line L6 on the connection line L5 was added to the reduction reaction gas dehumidified by the dehumidifier 7. O: 0.23%) was mixed and introduced into the second reactor 1B under the conditions of 1000 ° C. and 5 atm (see FIG. 2 and (G) shown in Table 1 below). At this time, the atmosphere in the second reactor 1B was preliminarily filled with a catalyst containing Ni as a main component, and an oxidation reaction as shown in the following equations (6) and (8) was generated.
¹³ C + H ₂ ¹⁶ O → ¹³ C ¹⁶ O + H ₂ ... (6)
¹³ CH ₄ + H ₂ ¹⁶ O → ¹³ C ¹⁶ O + 3H ₂ ... (8)

Then, the oxidation reaction was the oxidation reaction gas in the second reactor ^{_{1B (34.96Nm 3 /h,CO:2.90%,H 2: 14.30}} %, CH 4: 0.39%, H 2 O: 81.57%, CO ₂ : 0.83%; see (H) in FIG. 2 and Table 1 below) was cooled in a dehydrator 2 made of a chiller for dehydration treatment.
Next, the reaction gas after the dehydration treatment was introduced into the first adsorber 31 to carry out a more sufficient dehydration treatment, and then introduced into the second adsorber 32 _{to remove CO 2} (FIG. 2 and the table below). (See (J) and (K) shown in 1).

Next, the _{reaction gas from which CO 2} has been removed by the second adsorption column is introduced into the first distillation column 41 _{to remove H 2} , and further, CH ₄ is removed by the second distillation column 42 to remove the final line L13. Carbon monoxide isotope CO ( ¹⁶ O: 99.7%, ¹⁷ O: 0.039%, ¹⁸ O: 0.21%) was obtained through (16 O: 99.7%, 18 O: 0.21%) ((M) shown in FIG. 2 and Table 1 below), ( See R)). _{At this time, H 2} removed by the first distillation column 41 is forwarded to the second adsorber 32 by the adsorber regeneration processing unit 6 for regeneration processing (flow rate: 5.0 Nm ³ / h). _{Together with the CO 2} removed by the second adsorber 32, the CO 2 was returned to the first reactor 1A by the second return line 52 via the first return line 51 and the raw material supply line L1 and subjected to rereaction (FIGS. 2 and 2). See (L) and (Q) shown in Table 1 below). _{Further, CH 4} removed in the second distillation column 42 was also returned to the first reactor 1A via the first return line 51, the second return line 52, and the raw material supply line L1 and subjected to rereaction (FIG. FIG. 2 and (N) and (Q) shown in Table 1 below).

As shown in (R) in Table 1 below, ¹⁶ O was selectively concentrated in ^{the obtained carbon monoxide isotope CO, and high-purity C 16} O was obtained.

From the results of the examples described above, the oxygen isotope substitution method and the oxygen isotope substitution apparatus according to the present invention can efficiently introduce an arbitrary oxygen isotope into the carbon monoxide CO at an arbitrary ratio. It is clear that it is possible to obtain the desired stable carbon monoxide isotope with high purity.

According to the oxygen isotope substitution method and the oxygen isotope substitution apparatus of the present invention, ^{stable carbon monoxide isotopes including carbon isotopes 12} C and ¹³ C can be selectively obtained, and in particular, carbon isotope ¹³ C. Since it is possible to produce a product containing a high concentration of ¹³ C ¹⁶ O containing a high concentration of 13 C 16 O, it is suitable for, for example, manufacturing a tracer in the medical field or the like.

1A ... 1st reactor 1B ... 2nd reactor 2 ... dehydrator 3 ... adsorber 31 ... 1st adsorber 32 ... 2nd adsorber 4 ... distillation column 41 ... 1st distillation column 42 ... 2nd distillation column 5 ... Return unit 51 ... 1st return line 52 ... 2nd return line 6 ... Adsorber regeneration processing unit 7 ... Dehumidifier 10 ... Oxygen isotope replacement device L1 ... Raw material supply line L2 ... Hydrogen supply line L3 ... Connection line L4 ... Drainage line L5 ... Connection line L6 ... Water supply line L7 ... Connection line L8 ... Connection line L9 ... Drain line L10 ... Connection line L11 ... Connection line L12 ... Connection line L13 ... Final line

Claims (10)

An oxygen isotope substitution method that introduces an arbitrary oxygen isotope into carbon monoxide.
A reduction reaction step of reacting carbon monoxide CO containing at least carbon isotopes ¹² C and ¹³ _{C with H 2} in the first reactor ^{to convert it to either 12} C, ^{13 C or hydrocarbon.
Either 12} C, ¹³ C or hydrocarbon produced in the reduction reaction step is reacted with H ₂ ^{O containing oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O in the second reactor to obtain arbitrary oxygen. By introducing an isotope, one of the stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ O is selected. An oxygen isotope substitution method comprising: Further, the oxidation reaction gas after the reaction in the oxidation reaction step is dehydrated _{to remove H 2} O which is a by-product, and then CO ₂ which is a by-product is recovered by using an adsorber.
Next, the stable carbon monoxide isotope produced in the oxidation reaction step is recovered by recovering the _{unreacted hydrocarbon and the by-product H 2} in the oxidation reaction step using a distillation column. The oxygen isotope substitution method according to claim 1, further comprising a purification step of purifying the body with high purity. Further, it is characterized by having a return step of returning the unreacted hydrocarbon and the by-product CO _{2 recovered in the purification step to the reduction reaction step for re-reaction.} The oxygen isotope substitution method according to claim 2. The oxygen isotope according to claim 2 or 3, wherein the purification step _{returns H 2 recovered in the distillation column to the adsorber and regenerates the adsorber.} Replacement method. Further, between the reduction reaction step and the oxidation reaction step, ¹² C, ¹³ C or hydrocarbons produced in the reduction reaction step are dehumidified in a dehumidifier to obtain H ₂ O which is a by-product. The oxygen isotope substitution method according to any one of claims 1 to 4, wherein a dehumidifying step for removing is provided. An oxygen isotope substitution device that introduces an arbitrary oxygen isotope into carbon monoxide.
A first reactor that internally reacts carbon monoxide CO containing at least carbon isotopes ¹² C and ¹³ _{C with H 2} to convert it to either ¹² C, ^{13 C or hydrocarbons.
Any of the 12} C, ¹³ C or hydrocarbons produced in the first reactor is internally reacted with H ₂ ^{O containing the oxygen isotopes 16} O, ¹⁷ O and ¹⁸ O to produce any oxygen isotope. By introduction, one of the stable carbon monoxide isotopes ¹² C ¹⁶ O, ¹² C ¹⁷ O, ¹² C ¹⁸ O, ¹³ C ¹⁶ O, ¹³ C ¹⁷ O or ¹³ C ¹⁸ O is selectively produced. An oxygen isotope substitution apparatus comprising: Further, a dehydrator that dehydrates the oxidation reaction gas after the reaction in the second reactor to remove _{H 2 O as a by-product.}
An adsorber that adsorbs and recovers _{CO 2} which is a by-product,
By recovering the unreacted hydrocarbon and the by-product H ₂ in the second reactor, the stable carbon monoxide isotope produced in the second reactor is purified to high purity. The oxygen isotope substitution apparatus according to claim 6, further comprising a distillation column. _{Further, it is provided with a return unit for returning the CO 2} which is the by-product recovered by the adsorber and the hydrocarbon which is the unreacted product recovered by the distillation column to the first reactor. The oxygen isotope substitution apparatus according to claim 7. _{The seventh or eighth aspect of the present invention, further comprising an adsorber regeneration processing unit for returning the H 2} recovered in the distillation column to the adsorber and performing the regeneration processing of the adsorber. Oxygen isotope substitution device. Further, between the first reactor and the second reactor, ¹² C, ¹³ C or a hydrocarbon produced by the first reactor is dehumidified in the dehumidifier, and H is a by-product. The oxygen isotope substitution apparatus according to any one of claims 6 to 9, wherein a dehumidifier for removing _{2 O is provided.}

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