JP6902070B2 - Carbon monoxide stable isotope concentrator and carbon monoxide stable isotope enrichment method - Google Patents

Description

The present invention relates to a carbon monoxide stable isotope concentrator and a carbon monoxide stable isotope enrichment method.

There are two types of stable isotopes of ^{carbon, 12} C and ^{13 C.} Of these, ^13C is currently used mainly as a tracer in the natural sciences and medical fields.

As a method for concentrating stable isotopes to a high concentration of 99% or more, a technique that combines isotope scrambling with a distillation cascade process is known. Here, the distillation cascade process is a process in which a plurality of distillation columns are connected in a cascade manner, specific components to be concentrated in each distillation column are supplied to adjacent distillation columns, and the distillation columns are further concentrated. In addition, isotope scrambling is an exchange reaction in which atoms constituting a compound are randomly rearranged.

For the distillation of carbon monoxide, a technique that combines the above-mentioned distillation cascade process with isotope scrambling has come to be used. ^{In this technique, some of the 12} C ¹⁸ O molecules concentrated by the distillation cascade process are converted to ¹³ C ¹⁸ O by isotope scrambling ⁽¹³ C ¹⁶ O + ¹² C ¹⁸ O → ¹² C ¹⁶ O + ¹³ C ^18). O), isotope scrambled carbon monoxide is further concentrated in a distillation cascade process to more efficiently (in high yields) concentrate ¹³ CO ( ^{total of 13} C ¹⁶ O and ¹³ C ¹⁸ O). To do. By this technique, ^{carbon monoxide obtained in which 13} C ¹⁶ O and ¹³ C ¹⁸ O are concentrated to a high concentration of 99% or more in total is obtained.

However, carbon monoxide obtained by the above-mentioned technique ^{has a high concentration of 13} C ¹⁸ O, which is a combination with ¹⁸ O, which is a stable isotope of oxygen, and has a problem in being used as a tracer in the medical field.

For the above problems, Patent Document ^1, a combination of techniques that the presence proportion of lower ¹⁸ O impairment isotopic molecules containing ^{18 O,} to give a ¹³ CO product with a reduced abundance ratio of 13 ^{C 18} O There is. Specifically, in Patent Document 1, among a plurality of distillation columns connected in cascade, the distillation column between the distillation column arranged at the upstream end and the distillation column arranged at the downstream end is ¹⁸ O. A stable carbon monoxide isotope enricher to which an impaired device is connected is disclosed.

In the carbon monoxide stable isotope concentrator disclosed in Patent Document 1, in a distillation tower to which an ¹⁸ O attenuating device is connected, carbon monoxide enriched with a stable carbon monoxide isotope containing ^{13 C is discharged from the distillation tower. 18} withdrawn to ^O impairment device, ^{18 O} impairment device to an oxidation-reduction reaction in a part of the monoxide carbon isotope molecules containing ^{18 O,} converted to carbon monoxide stable isotope molecules containing ^{16 O, 18} Attenuates carbon monoxide stable isotope molecules, including O.

JP-A-2018-164884

By the way, in an industrial process, a general water-gas shift reaction is used as a redox reaction. The water-gas shift reaction has a positive reaction represented by the following formula (A) and a reverse reaction represented by the following formula (B).
(Positive reaction) ¹³ C ¹⁸ O + H ₂ ¹⁶ O → ¹³ C ¹⁶ O ¹⁸ O + H ₂ ... Equation (A)
(Reverse reaction) ¹³ C ¹⁶ O ¹⁸ O + H ₂ → ¹³ C ¹⁶ O + H ₂ ¹⁸ O ・ ・ ・ Equation (B)

Further, in the water gas shift reaction, the positive reaction is an exothermic reaction as shown in the following formula (C). For example, the equilibrium constant of a positive reaction at 25 ° C. is about 100,000.
CO + H ₂ O → CO ₂ + H ₂ K _298K = 1.03 × 10 ⁵・ ・ ・ Equation (C)

Therefore, in the reverse reaction of the water-gas shift reaction, in order to make the total amount of ¹³ CO ₂ ¹³ CO, it is necessary to carry out the reverse reaction in multiple stages under high temperature conditions. Further, in order to promote the reverse reaction, it is necessary to take the unreacted product at the time of the normal reaction or the product at the time of the reverse reaction out of the reaction system.
In Patent Document 1 described above, as a simple method for promoting the reverse reaction, the reaction gas generated during the reverse reaction is sufficiently cooled to condense water, and water as a reaction product is discharged.

However, carbon dioxide has a high solubility in water, and ¹³ CO ₂ is dissolved in a small amount in the condensed water. Therefore, there is a problem that a loss of ¹³ C occurs when the condensed water is discharged from ^{the 18 O impairment device.} The loss ratio due to the discharge of condensed water is ^{extremely small with respect to the amount of carbon monoxide introduced into the 18} O impairment device, but the loss during the concentration process greatly affects the final product volume.

On the other hand, a method is also conceivable in which the condensed water generated by the reverse reaction is reused as a part of the water supplied by the positive reaction without being discharged from the ^{18 O impairment device.} However, the condensed water generated in the reverse reaction includes many ^{18 O,} can not be impaired itself ^{18 O} is the purpose of a positive reaction in the water gas shift reaction.

The present invention has been made in view of the above problems, and is a carbon monoxide stable isotope concentrator and a carbon monoxide stable isotope enrichment device capable of concentrating ¹³ C ^{16 O to a high concentration and obtained in a high yield.} The challenge is to provide a method.

In order to achieve the above problems, the present invention adopts the following configuration.
[1] A carbon monoxide stable isotope concentrator that concentrates ¹³ C ^{16 O, which is a stable carbon monoxide isotope molecule.}
A group of distillation columns in which a plurality of distillation columns are cascaded to distill a raw material carbon monoxide containing a plurality of types of stable carbon monoxide isotope molecules and concentrate a stable carbon monoxide isotope molecule containing ^{13 C.}
An aqueous gas shift that is connected to at least one of the distillation columns other than the distillation column arranged at the downstream end of the distillation column group and includes a positive reaction represented by the following formula (1) and a reverse reaction represented by the following formula (2). ^{A 18} O attenuation device, which attenuates a stable carbon monoxide isotope molecule containing ¹⁸ O by a reaction, is provided.
The ¹⁸ O impairment device includes the first unit that performs the positive reaction and the first unit.
One or more second units located after the first unit and performing the reverse reaction, and
A third unit that collects the condensed water obtained by cooling the gas generated in the first unit and the second unit and heats the condensed water to separate the vapor phase.
It has a path for supplying the vapor phase from the third unit to the first unit.
Carbon monoxide stable isotope concentrator.
¹³ C ¹⁸ O + H ₂ ¹⁶ O → ¹³ C ¹⁶ O ¹⁸ O + H ₂ ... Equation (1)
¹³ C ¹⁶ O ¹⁸ O + H ₂ → ¹³ C ¹⁶ O + H ₂ ¹⁸ O ・ ・ ・ Equation (2)
[2] Part or all of carbon monoxide enriched with stable carbon monoxide isotope molecules including ¹³ C is extracted from the distillation column to which the ¹⁸ O impairment device is connected and introduced into the ^{18 O impairment device.} Being done
The carbon monoxide stable isotope concentrator according to the preceding item [1], wherein carbon monoxide in which carbon monoxide stable isotope molecules containing ^{18 O are impaired is returned from the 18} O impairment device to the distillation column.
[3] A carbon monoxide stable isotope enrichment method for concentrating ¹³ C ^{16 O, which is a carbon monoxide stable isotope molecule.}
Distillation that distills raw material carbon monoxide containing a plurality of types of carbon monoxide stable isotope molecules and concentrates carbon monoxide stable isotope molecules including ^{13 C in a group of distillation columns in which a plurality of distillation columns are cascaded.} Process and
Part or all of carbon monoxide enriched with stable carbon monoxide isotope molecules including ¹³ C was extracted from at least one of the distillation towers other than the distillation towers arranged at the downstream end of the distillation tower group. ^{The carbon monoxide stable isotope molecule containing 18} O contained in this carbon monoxide was ^{subjected to the above 18} by an aqueous gas shift reaction including a positive reaction represented by the following formula (1) and a reverse reaction represented by the following formula (2). A part of the carbon monoxide stable isotope molecule containing O is converted into the carbon monoxide stable isotope molecule containing ^{16 O, and the carbon monoxide stable isotope molecule containing 18} O is impaired to obtain carbon monoxide. Te, comprising ¹⁸ and ^O impairment step of returning the carbon monoxide to the distillation column, and
The ¹⁸ O impairment step includes the first step of performing the positive reaction and
After the first step, one or more second steps that carry out the reverse reaction, and
The first step and the third step of recovering the condensed water obtained by cooling the gas generated in the second step and heating the condensed water to separate the vapor phase are included.
A carbon monoxide stable isotope enrichment method for supplying the vapor phase to the first step.
¹³ C ¹⁸ O + H ₂ ¹⁶ O → ¹³ C ¹⁶ O ¹⁸ O + H ₂ ... Equation (1)
¹³ C ¹⁶ O ¹⁸ O + H ₂ → ¹³ C ¹⁶ O + H ₂ ¹⁸ O ・ ・ ・ Equation (2)

According to the carbon monoxide stable isotope concentrator and the carbon monoxide stable isotope enrichment method of the present invention, ¹³ C ¹⁶ O can be concentrated to a high concentration and obtained in a high yield.

It is a system diagram which shows the main part of the carbon monoxide stable isotope enrichment apparatus which concerns on embodiment of this invention. It is a reaction flow chart of the ¹⁸ O impairment apparatus which concerns on embodiment of this invention. It is a system diagram which shows the main part of the carbon monoxide stable isotope enrichment apparatus used in the comparative example 1. FIG. It is a reaction flow chart of ^{the 18} O impairment apparatus used in Comparative Example 1.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, showing embodiments.
In the drawings used in the following description, in order to make the features easier to understand, the featured parts may be enlarged for convenience, and the dimensional ratios of each component may not be the same as the actual ones. Absent.

(Carbon monoxide stable isotope concentrator)
FIG. 1 is a system diagram showing a main part of a carbon monoxide stable isotope concentrator according to an embodiment of the present invention.
The carbon monoxide stable isotope concentrator 100 of the present embodiment includes a group of distillation columns in which 13 distillation columns 1 to 13 are cascade-connected, an ¹⁸ O-damaging device 20, 13 capacitors 21, and 13 units. It includes a reboiler 22, a raw material supply line 30, a product lead-out line 31, an isotope-enriched gas extraction line 32, and an isotope-enriched gas return line 33.
Hereinafter, the nth distillation column from the upstream end of the distillation column group is referred to as the nth distillation column.
In FIG. 1, among the first to thirteenth distillation columns 1 to 13, the first distillation column 1 and the fourth distillation column to which high-purity carbon monoxide as a raw material is supplied are shown in FIG. Only 4 and the 9th to 13th distillation columns 9 to 13 are shown.

The first to thirteenth distillation columns 1 to 13 are a first distillation column 1, a second distillation column 2, a third distillation column 3, and a fourth distillation to which high-purity carbon monoxide as a raw material is supplied. Tower 4, Fifth Distillation Tower 5, Sixth Distillation Tower 6, Seventh Distillation Tower 7, Eighth Distillation Tower 8, Ninth Distillation Tower 9, Tenth Distillation Tower 10, Eleventh Distillation Tower The eleventh, the twelfth distillation column 12, and the thirteenth distillation column 13 (the distillation column at the downstream end of the distillation column group) are cascade-connected in this order.

The first to thirteenth distillation columns 1 to 13 concentrate low-boiling carbon monoxide isotope molecules on the top side of the column by low-temperature distillation of cooled carbon monoxide (performing a distillation cascade process). Carbon monoxide isotope molecules with a high boiling point are concentrated on the bottom side of the column.
Of the first to thirteenth distillation columns 1 to 13, the fourth distillation column 4 to which the raw material is supplied has the largest distillation load, and therefore has the largest diameter. Further, the distillation load is gradually reduced from the fourth distillation column 4 toward the upstream end and the downstream end (the diameter of the column is decreasing).
A rectification stage (shelf), a regular filler, an irregular filler, and the like (none of which are shown) are provided in the first to thirteenth distillation columns 1 to 13, respectively.

One capacitor 21 is provided for each distillation column (first to thirteenth distillation columns 1 to 13).
The condenser 21 is provided on a circulation line 37 whose ends are connected at different positions on the top of each distillation column. The condenser 21 has a function of liquefying the gas that has risen in the distillation column by heat exchange and lowering the inside of the distillation column again. In this example, a heat medium fluid circulation line 39 that circulates the heat medium fluid through a plurality of capacitors 21 is provided, and heat exchange is performed by the heat medium fluid that circulates in the heat medium fluid circulation line 39. ing.

One reboiler 22 is provided for each distillation column.
The reboiler 22 is provided on a circulation line 38 in which both ends are connected at different positions on the bottom of each distillation column. The reboiler 22 has a function of vaporizing the liquid that has descended in the distillation column by heat exchange and raising the inside of the distillation column again. In this example, a heat medium fluid circulation line 40 that circulates the heat medium fluid through the plurality of reboilers 22 is provided, and heat exchange is performed by the heat medium fluid that circulates in the heat medium fluid circulation line 40. ing.

One end of the raw material supply line 30 is connected to the intermediate portion of the fourth distillation column 4. The raw material supply line 30 is a line for supplying high-purity carbon monoxide (raw material carbon monoxide) to the intermediate portion of the fourth distillation column 4. The raw material supply line 30 is provided with a valve.
The middle portion of the distillation column indicates a position other than the top and bottom of the distillation column.
High purity means that the total purity of carbon monoxide is 99.999% or more.
The high-purity carbon monoxide supplied from the raw material supply line 30 contains 6 types of stable isotope molecules shown in Table 1 below. The abundance ratio of each stable isotope molecule is usually the same as the natural abundance ratio shown in Table 1.

One end of the isotope concentrated gas extraction line 32 is connected to the intermediate portion of the tenth distillation column 10, and the other end is connected to the ¹⁸ O impairment device 20. A valve is provided in the isotope concentrated gas extraction line 32.
The isotope concentrated gas extraction line 32 derives a part or all of carbon monoxide from the middle part of the tenth distillation column 10 when the valve is open, ^{and supplies it to the 18} O impairment device 20. ing.
Carbon monoxide derived from the intermediate portion of the tenth distillation column 10 was concentrated by distillation column 10 in the first to ^tenth, the carbon monoxide stable isotope molecules ^{(13 C 16} O containing ¹³ C , ¹³ C ¹⁸ O, etc.). Also, ^{usually, 12} carbon monoxide stable isotope molecules comprising ^{C (12 C 16 O, 12} C 18 O , etc.) are also included.

^{The 18} O depletion device 20 utilizes an aqueous gas shift reaction including a positive reaction represented by the following formula (1) and a reverse reaction represented by the following formula (2), and contains, for example, a proportion of ¹⁸ O larger than the natural abundance ratio. A part of carbon monoxide stable isotope molecules ( ¹³ C ¹⁸ O, ¹² C ¹⁸ O, etc.) is converted into carbon monoxide stable isotope molecules containing ¹⁶ O, and carbon monoxide stable isotope molecules containing ^{18 O.} Is impaired.

・ Water-gas shift reaction (positive reaction) ¹³ C ¹⁸ O + H ₂ ¹⁶ O → ¹³ C ¹⁶ O ¹⁸ O + H ₂ ... Equation (1)
(Reverse reaction) ¹³ C ¹⁶ O ¹⁸ O + H ₂ → ¹³ C ¹⁶ O + H ₂ ¹⁸ O ・ ・ ・ Equation (2)

^{Specifically, in the forward reaction, 13} C ¹⁶ O ¹⁸ O is produced by reacting with water having a high natural abundance ratio of ^{16 O introduced into the 18} O impairment device 20 from the introduction path 34, and further in the reverse reaction, ¹³ By generating C ¹⁶ O, some ¹³ C ¹⁸ O ^{can be converted to 13} C ¹⁶ O as a result.

^{The 18} O impairment device 20 is provided with a water recycling line (route) 36 for recovering water, which is a reaction / product of the water gas shift reaction, and reintroducing a part of the recovered water into the introduction route. There is.
Further, the ¹⁸ O impairment device 20 is provided with discharge paths 35 and 41 for separating hydrogen as a product and water that is not reused from carbon monoxide and discharging them to the outside of the device, respectively.

FIG. 2 is a schematic diagram showing the configuration and reaction flow of ^{the 18 O impairment device 20 of the present embodiment.}
As shown in FIG. 2, the ¹⁸ O impairment device 20 includes a water vaporization unit 60, a positive reaction unit 61, a water condensing unit 62, a reverse reaction unit 63, a hydrogen separation unit 64, and a recovered water heating unit 65.

The water vaporization unit 60 vaporizes water having a high natural abundance ratio of ^{16 O introduced into the 18} O impairment device 20 from the introduction path 34.

The positive reaction unit (first unit) 61 performs the positive reaction represented by the above formula (1). The water vaporized by the water vaporization unit 60 is introduced into the positive reaction unit 61.

The reverse reaction unit (second unit) 63 is located in the subsequent stage (secondary side) of the normal reaction unit 61. The reverse reaction unit 63 is connected in series in three stages. The reverse reaction unit 63 performs the reverse reaction represented by the above formula (2).

The water condensing section 62 is located on the secondary side of the forward reaction section 61 and each reverse reaction section 63, respectively. The mixed gas after the reaction discharged from the normal reaction unit 61 and the reverse reaction unit 63 is supplied to each water condensing unit 62. The water condensing unit 62 has a function of cooling the mixed gas by heat exchange to liquefy it and separating it into condensed water and a substance other than water.

The hydrogen separation unit 64 is located on the secondary side of the reverse reaction unit 63 in the final stage. The mixed gas after the reaction is introduced into the hydrogen separation unit 64 from the reverse reaction unit 63 of the third stage, and the ^{carbon monoxide stable isotope molecule containing 18} O is separated into impaired carbon monoxide and hydrogen. .. The hydrogen separation method is not particularly limited, and examples thereof include adsorption, membrane separation, and distillation. The separated hydrogen is discharged to the outside of the device from the discharge path 41.

The recovered water heating unit (third unit) 65 is connected to each water condensing unit 62. Condensed water is supplied to the recovered water heating unit 65 from each water condensing unit 62. In the recovered water heating unit 65, the condensed water is heated again to separate the steam phase. The separated vapor phase is reintroduced into the water vaporization section 60 via the water recycling line (path) 36 and used for the reaction in the positive reaction section 61. On the other hand, the separated liquid phase is discharged to the outside of the device from the discharge path 35.

The heating temperature in the recovered water heating unit (third unit) 65 is preferably 80 ° C. to 95 ° C., more preferably 85 ° C. to 90 ° C. When the heating temperature is in the above range, the condensed water can be separated into a vapor phase and a liquid phase, and the carbon dioxide dissolved in the condensed water moves to the vapor phase. By reintroducing the vapor phase containing carbon dioxide into the water vaporization unit 60, the loss of the C component can be prevented. Liquid phase containing unwanted _H ^{2 18} O is discharged from the discharge path 35 to the outside of the apparatus.

One end of the isotope concentrated gas return line 33 is ^{connected to the 18} O impairment device 20, and the other end is connected to the intermediate portion of the tenth distillation column 10. A valve is provided in the isotope concentrated gas return line 33.
Isotopically enriched gas return line 33 when the valve is in the open state, ^{18 O} impairment device 20 of carbon monoxide which is highly purified from (hydrogen separation unit 64), tenth distillation column 10 (carbon monoxide Is returned to the middle part of the distillation column) from which it was derived.
The carbon monoxide returned to the tenth distillation tower 10 is a stable carbon monoxide isotope molecule containing ^{18 O (12} C ¹⁸ O, ¹³ C ¹⁸ ) as compared with the time when it was derived from the tenth distillation tower 10. O) is ^impaired, carbon monoxide stable isotope molecules ^{(12 C 16 O, 13 C} 16 O) is concentrated including ¹⁶ O.
The carbon monoxide returned to the tenth distillation column 10 is distilled in the eleventh to thirteenth distillation columns 11 to ^13, and the carbon monoxide stable isotope molecule containing 13 C is further concentrated.

One end of the product lead-out line 31 is connected to the lower part of the thirteenth distillation column 13. The product out-licensing line 31 is a line for out-licensing a ^{13 CO product. The 13} CO product is carbon monoxide containing ¹³ C ¹⁶ O concentrated to a high concentration (eg, 99% or more) ^{and 13} C ^{18 O.}

In the carbon monoxide stable isotope concentrator 100 described above, the first distillation column 1 (distillation column arranged at the upstream end) and the thirteenth distillation column 13 (distillation arranged at the downstream end) ^{Since the 18} O depletion equipment is connected to the distillation column between the column) ^{, 13} CO can be efficiently concentrated.
In addition, since there is no loss of stable carbon monoxide isotope in ^{the 18 O impairment device, a 13} CO product can be obtained in a high yield.
Further, the obtained ¹³ CO product contains ¹³ C ¹⁶ O in a high concentration, and ^{the abundance ratio of 13} C ¹⁸ O is not too high as compared with the natural abundance ratio, so that it is useful as a tracer in the medical field and the like.

(Stable isotope enrichment method for carbon monoxide)
Next, the carbon monoxide stable isotope enrichment method according to the embodiment of the present invention will be described with reference to FIG. ^{In this embodiment, 13} CO is concentrated using the carbon monoxide stable isotope concentrator 100 shown in FIG.
The carbon monoxide stable isotope enrichment method of the present embodiment includes a distillation step and an ¹⁸ O impairment step.

In the distillation step, high-purity carbon monoxide (a plurality of types of monoxide) supplied from the raw material supply line 30 to the fourth distillation column 4 of the distillation column group in which the first to thirteenth distillation columns 1 to 13 are cascade-connected. Raw material carbon monoxide containing carbon stable isotope molecules) is distilled in the distillation column groups (1st to 13th distillation columns 1 to 13) to concentrate carbon monoxide stable isotope molecules containing ^{13 C.} ..

^{In the 18} O impairment step, first, between the tenth distillation column 10 of the distillation column group (between the first distillation column 1 arranged at the upstream end and the thirteenth distillation column 13 arranged at the downstream end). A part or all of carbon monoxide enriched with a stable carbon monoxide isotope molecule containing ¹³ C is extracted from the distillation column) ^{and introduced into the 18} O attenuating device 20 through the isotope enriched gas extraction line 32. ^{Next, the carbon monoxide stable isotope molecule containing 18} O contained in the carbon monoxide is subjected to an aqueous gas shift reaction including a positive reaction represented by the following formula (1) and a reverse reaction represented by the following formula (2). Then, it is converted into a carbon monoxide stable isotope molecule containing ^{16 O, and a carbon monoxide stable isotope molecule containing 18} O is impaired to obtain carbon monoxide. The carbon monoxide is then returned to the tenth distillation column 10 through the isotope concentrated gas return line 33.

With reference to FIG. ^2, it will be described in detail ¹⁸ O impairment process using ¹⁸ O impairment device 20.
^{In the 18} O impairment step, first, ^{water having a high natural abundance ratio of 16} O introduced from the introduction path 34 is vaporized by the water vaporization unit 60 and supplied to the positive reaction unit 61. In the positive reaction section 61, carbon monoxide and water vapor are mixed and subjected to a positive reaction represented by the above formula (1) (first step).
Next, in the water condensing section 62 in the subsequent stage of the positive reaction section 61, the mixed gas (gas) generated in the reaction in the positive reaction section 61 is cooled by heat exchange and liquefied to obtain condensed water. Next, in the water condensing section 62, the condensed water and a substance other than water are separated.

Next, the condensed water recovered by the water condensing section 62 is sent to the recovered water heating section 65 and heated again. Of the heated condensed water, only the steam phase is separated (third step). The separated vapor phase is reintroduced into the water vaporization unit 60, supplied to the positive reaction unit 61, and used for the positive reaction. On the other hand, the liquid phase of the condensed water is discharged from the discharge path 35.

Next, the reaction gas separated from the condensed water in the water condensing section 62 in the subsequent stage of the positive reaction section 61 is introduced into the reverse reaction section 63 in the first stage. The reverse reaction unit 63 causes a reverse reaction (second step). The mixed gas (gas) generated by the reaction in the reverse reaction unit 63 is separated into condensed water and a substance other than water by the water condensing unit 62 located in the subsequent stage, and the condensed water passes through the recovered water heating unit 65. It is reintroduced to the water vaporization unit 60. For the reverse reaction, the same step is repeated in three steps.

Next, the mixed gas (gas) generated in the reaction of the third stage is introduced into the hydrogen separation unit 64, and the ^{carbon monoxide stable isotope molecule containing 18} O is separated into impaired carbon monoxide and hydrogen. .. The ^{carbon monoxide stable isotope molecule containing the separated 18} O is impaired and returned to the tenth distillation column 10 through the isotope concentrated gas return line 33. The separated hydrogen is discharged from the discharge path 41.

^{In the reaction flow of the 18} O attenuating device 20 of the present embodiment, the condensed water recovered by each water condensing unit 62 is heated by the recovered water heating unit 65, so that the carbon dioxide dissolved in the condensed water moves to the steam phase. By reintroducing this vapor phase into the water vaporization unit 60, the loss of the C component can be eliminated.

Since the recovered condensate is ^{18 O} concentration is higher than the natural abundance ratio, water in the vapor phase to be re-introduced into the moisture reduction unit 60 is small in comparison with the normal introduction water, ¹⁸ O The function of impairment is not impaired.

^{The 18} O impairment step is carried out in the middle of the distillation step. That is, the distillation step is divided into a first distillation step performed in the first to tenth distillation columns 1 to 10 and a second distillation step performed in the eleventh to thirteenth distillation columns 11 to 13. , With an ¹⁸ O attenuation step between them.

The high-purity carbon monoxide supplied from the raw material supply line 30 contains the six types of stable isotope molecules shown in Table 1 above. The abundance ratio of each stable isotope molecule is usually the same as the natural abundance ratio shown in Table 1.

Immediately after the start of the distillation step (immediately after the start of each distillation column), each concentration of each stable isotope molecule is uniform in all the distillation columns (first to thirteenth distillation columns 1 to 13). Then, over time, carbon monoxide stable isotope molecules with relatively high boiling points, especially ¹³ C ¹⁶ O, ¹² C ¹⁸ O, and ¹³ C ¹⁸ O, are concentrated near the middle of the tenth distillation column 10. ..

Therefore, the carbon monoxide extracted from the intermediate portion of the tenth distillation column 10 to the ^{18 O depletion device 20 in the first distillation step is 13} C ¹⁶ O, ¹² C ¹⁸ O, ¹³ C, as compared with the raw materials. ¹⁸ O is concentrated.

^{In the 18 O impairment step, a part of 12} C ¹⁸ O and ¹³ C ¹⁸ O contained in the carbon monoxide extracted from the middle part of the 10th distillation column 10 is converted into ¹² C ¹⁶ O or ¹³ C ^{16 O.} Will be done. Therefore, the total concentration of carbon monoxide returned to the tenth distillation column 10 in ^{the 18 O impairment step was lower than that at the time of extraction, and the total concentrations of 12} C ¹⁸ O and ¹³ C ¹⁸ O were lower, and ¹² C ¹⁶ O and ¹³ C The total concentration of ^{16 O is high.}

In the second distillation step, a stable carbon monoxide isotope molecule ( ¹³ C ^{16 ) containing 13} C, which has a relatively high boiling point, contained in the carbon monoxide returned to the tenth distillation column 10 in the ^{18 O attenuation step.} O, ¹³ C ¹⁸ O) is concentrated near the bottom of the thirteenth distillation column 13. The carbon monoxide distilled at this time ^{is converted into 12} C ¹⁶ O or ¹³ C ^{16 O in a part of 12} C ¹⁸ O and ¹³ C ¹⁸ O in the ¹⁸ O impairment step, so that it is converted into 12 C 16 O or 13 C 16 O in the second distillation step. ^{Even if 12} C ¹⁸ O and ¹³ C ¹⁸ O are concentrated, the amount is limited. Therefore, is derived through the product outlet line 31 from the distillation column 13 of the ^{13, 13} C is a high concentration, ¹⁸ O concentration in the ¹³ CO product isotope concentration of, for example, ¹³ C enriched at least 99%, the tracer It is low enough to be used as, for example, the ¹⁸ O isotope concentration is 5% or less.

In the carbon monoxide stable isotope enrichment method described above, since the ¹⁸ O impairment step is performed in ^{the middle of the distillation cascade process (distillation step), 13} C ¹⁶ O can be efficiently concentrated.
In addition, since there is no loss of stable carbon monoxide isotope in ^{the 18 O impairment step, a 13} CO product can be obtained in a high yield.
The obtained ¹³ C ¹⁶ O product contains ¹³ C ¹⁶ O in a high concentration, and ^{the abundance ratio of 13} C ¹⁸ O is not too high as compared with the natural abundance ratio, so that it is useful as a tracer in the medical field and the like.

Although the carbon monoxide stable isotope enrichment apparatus and the carbon monoxide stable isotope enrichment method of the present invention have been described above by showing embodiments, the present invention is not limited to these embodiments. Each configuration in the above embodiment and a combination thereof are examples, and the configuration can be added, omitted, replaced, and other changes can be made without departing from the spirit of the present invention.
For example, the number of distillation columns (cascade-connected distillation columns) constituting the distillation column group is not limited to 13, and can be any number. The distillation column is not limited to a packed column filled with a regular packed bed, and may be a packed column or a shelf column filled with an irregular packed bed.
^{The 18} O impairment device is not limited to the tenth distillation column 10, and may be a distillation column other than the tenth distillation column 10. However, ¹⁸ at least one of ^O impairment device is connected distillation columns are distillation columns other than the distillation column disposed on the downstream end of the distillation column group.
^{The 18} O impairment device may be connected to a plurality of distillation columns.
^The reverse reaction section 63 and the reverse reaction step constituting the 18 O impairment device are not limited to three steps, and the number of reaction steps can be arbitrary depending on the reaction conditions.
The above-mentioned condenser 21 and reboiler 22 are not indispensable for each distillation column, and may not be provided when the gas rise is sufficient due to the pressure difference between the front and rear distillation columns, the pump, the blower, and the like.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

(Example 1)
^{In Example 1, 13} C ¹⁶ O was concentrated using the carbon monoxide stable isotope concentrator 100 shown in FIG. ^{The impairment step in the 18} O impairment device 20 was performed according to the flow shown in FIG. The composition of the raw material carbon monoxide to be supplied is as shown in Table 1 above.
The supply amount of raw material carbon monoxide was 12.0 Nm ³ / h, and the amount of carbon monoxide extracted to the ^{18 O impairment device 20 was 3.00 Nm 3} / h.
^{In the 18} O impaired equipment 20, the cooling temperature in the water condensing section 62 was set to 5 ° C., and the heating temperature in the recovered water heating section 65 was set to 90 ° C.

The abundance ratio of stable isotope molecules of the ¹³ CO product delivered from the thirteenth distillation column 13 when the apparatus was stabilized was as shown in Table 2. From Table 2, even if a part of the recovered condensed water was reintroduced into the positive reaction section 61 via the water vaporization section 60, the ^{function of suppressing the 18} O enrichment in the product was not impaired.
The amount of carbon monoxide returned from the ^{18 O impairment device 20 and the amount of 13} CO products delivered from the thirteenth distillation column 13 are as shown in Table 3. From Table 3, ¹³ C of the ratio ⁽¹³ C yield) of the raw material carbon monoxide to ¹³ C content in the product was about 90%.

(Comparative Example 1)
^{In Comparative Example 1, 13} CO was concentrated using the carbon monoxide stable isotope concentrator 200 shown in FIG. Monoxide carbon isotope enrichment apparatus 200, ^{18 O} water is the reaction / product in impairment device 20 is recovered, the water recycle line 36, and the recovered water heating unit 65 not to reintroduce a part of the recovered water Other than that, it is the same as the carbon monoxide stable isotope concentrator 100. In addition, the entire amount of water, which is a reaction / product, is discharged from the discharge path 35.
^{The reaction in the 18} O impairment device 20 was carried out according to the flow shown in FIG.
^{The supply amount of the raw material carbon monoxide was 12.0 Nm 3} / h as in Example 1, and the amount of carbon monoxide extracted to ^{the 18} O impairment device 20 was 3.00 Nm ³ / h.
^{In the 18} O impairment device 20, the cooling temperature at the water condensing section 62 was set to 5 ° C.
The abundance ratio of stable isotope molecules of the ¹³ CO products delivered from the thirteenth distillation column 13 when the apparatus was stabilized was as shown in Table 4.
The amount of carbon monoxide returned from the ^{18 O impairment device 20 and the amount of 13} CO products sent from the thirteenth distillation column 13 were as shown in Table 5. From Table 5, ^{the yield of 13C} was about 80%. ^{The loss rate on the 18} O impairment device was about 0.5%, but ^{the yield on the 13} CO product was reduced by about 10%.

The present invention is a distillation apparatus for distilling an ultra-low temperature fluid, and uses a distillation apparatus provided with a group of distillation columns in which a plurality of distillation columns are cascaded, and is stable in carbon monoxide, which exists in a very small amount in nature. applicable to isotope molecule ^{(13 C} 16 ^O) CO isotope enrichment apparatus and carbon monoxide stable isotope enrichment method for concentrating.

1, 4, 9, 10, 11, 12, 13 ... Distillation column 20 ... ¹⁸ O Impaired equipment 21 ... Condenser 22 ... Recycler 30 ... Raw material supply line 31 ... Product out-licensing line 32 ... isotope concentrated gas extraction line 33 ... isotope concentrated gas return line 34 ... introduction route 35, 41 ... discharge route 36 ... water recycling line (route)
60 ・ ・ ・ Water vaporization part 61 ・ ・ ・ Positive reaction part (1st unit)
62 ・ ・ ・ Water condensing part 63 ・ ・ ・ Reverse reaction part (2nd unit)
64 ・ ・ ・ Hydrogen separation part 65 ・ ・ ・ Recovery water heating part (3rd unit)

Claims (3)

A carbon monoxide stable isotope concentrator that concentrates ¹³ C ¹⁶ O, which is a stable carbon monoxide isotope molecule.
A group of distillation columns in which a plurality of distillation columns are cascaded to distill a raw material carbon monoxide containing a plurality of types of stable carbon monoxide isotope molecules and concentrate a stable carbon monoxide isotope molecule containing ^{13 C.}
An aqueous gas shift that is connected to at least one of the distillation columns other than the distillation column arranged at the downstream end of the distillation column group and includes a positive reaction represented by the following formula (1) and a reverse reaction represented by the following formula (2). ^{A 18} O attenuation device, which attenuates a stable carbon monoxide isotope molecule containing ¹⁸ O by a reaction, is provided.
The ¹⁸ O impairment device includes the first unit that performs the positive reaction and the unit.
One or more second units located after the first unit and performing the reverse reaction, and
A third unit that collects the condensed water obtained by cooling the gas generated in the first unit and the second unit and heats the condensed water to separate the vapor phase.
It has a path for supplying the vapor phase from the third unit to the first unit.
Carbon monoxide stable isotope concentrator.
¹³ C ¹⁸ O + H ₂ ¹⁶ O → ¹³ C ¹⁶ O ¹⁸ O + H ₂ ... Equation (1)
¹³ C ¹⁶ O ¹⁸ O + H ₂ → ¹³ C ¹⁶ O + H ₂ ¹⁸ O ・ ・ ・ Equation (2) A part or all of carbon monoxide enriched with a stable carbon monoxide isotope molecule containing ¹³ C was extracted from the distillation column to which the ¹⁸ O impairment device was connected and introduced into the ^{18 O impairment device.}
The carbon monoxide stable isotope concentrator according to claim 1, wherein carbon monoxide in which carbon monoxide stable isotope molecules containing ^{18 O are impaired is returned from the 18} O impairment device to the distillation column. A carbon monoxide stable isotope enrichment method for concentrating ¹³ C ¹⁶ O, which is a stable carbon monoxide isotope molecule.
Distillation that distills raw material carbon monoxide containing a plurality of types of carbon monoxide stable isotope molecules and concentrates carbon monoxide stable isotope molecules including ^{13 C in a group of distillation columns in which a plurality of distillation columns are cascaded.} Process and
Part or all of carbon monoxide enriched with stable carbon monoxide isotope molecules including ¹³ C was extracted from at least one of the distillation towers other than the distillation towers arranged at the downstream end of the distillation tower group. ^{The carbon monoxide stable isotope molecule containing 18} O contained in this carbon monoxide was ^{subjected to the above 18} by an aqueous gas shift reaction including a positive reaction represented by the following formula (1) and a reverse reaction represented by the following formula (2). A part of the carbon monoxide stable isotope molecule containing O is converted into the carbon monoxide stable isotope molecule containing ^{16 O, and the carbon monoxide stable isotope molecule containing 18} O is impaired to obtain carbon monoxide. Te, comprising ¹⁸ and ^O impairment step of returning the carbon monoxide to the distillation column, and
The ¹⁸ O impairment step includes the first step of performing the positive reaction and
After the first step, one or more second steps that carry out the reverse reaction, and
The first step and the third step of recovering the condensed water obtained by cooling the gas generated in the second step and heating the condensed water to separate the vapor phase are included.
A carbon monoxide stable isotope enrichment method for supplying the vapor phase to the first step.
¹³ C ¹⁸ O + H ₂ ¹⁶ O → ¹³ C ¹⁶ O ¹⁸ O + H ₂ ... Equation (1)
¹³ C ¹⁶ O ¹⁸ O + H ₂ → ¹³ C ¹⁶ O + H ₂ ¹⁸ O ・ ・ ・ Equation (2)

Images