CA1135940A - Process for recombination of oxygen with hydrogen - Google Patents
Process for recombination of oxygen with hydrogenInfo
- Publication number
- CA1135940A CA1135940A CA000347053A CA347053A CA1135940A CA 1135940 A CA1135940 A CA 1135940A CA 000347053 A CA000347053 A CA 000347053A CA 347053 A CA347053 A CA 347053A CA 1135940 A CA1135940 A CA 1135940A
- Authority
- CA
- Canada
- Prior art keywords
- noble metal
- heavy
- metal catalyst
- column
- oxygen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
Abstract
ABSTRACT OF THE DISCLOSURE
The recombination of oxygen with heavy hydrogen is carried out by allowing a flow of gas containing oxygen and heavy hydrogen to ascend in a reaction column charged with a noble metal catalyst and allowing a flow of water containing heavy hy-drogen peroxide to descend in said reaction column. Thus, both the recombination of oxygen with heavy hydrogen and the decompo-sition of heavy hydrogen peroxide are carried out simultaneously in one and the same reaction column to produce heavy water.
The recombination of oxygen with heavy hydrogen is carried out by allowing a flow of gas containing oxygen and heavy hydrogen to ascend in a reaction column charged with a noble metal catalyst and allowing a flow of water containing heavy hy-drogen peroxide to descend in said reaction column. Thus, both the recombination of oxygen with heavy hydrogen and the decompo-sition of heavy hydrogen peroxide are carried out simultaneously in one and the same reaction column to produce heavy water.
Description
The present inven-tion relates to a ~w~-*i*-i~ps~wY~
process for the recombination of oxygen with heavy hydrogen formed by the radiolysis of heavy water in, for example, a heavy water-moderated ligh-t water-cooled reactor of pressure tube type.
Heavy water D20 used as moderator reacts as Eollows under an influence oE radiation:
process for the recombination of oxygen with heavy hydrogen formed by the radiolysis of heavy water in, for example, a heavy water-moderated ligh-t water-cooled reactor of pressure tube type.
Heavy water D20 used as moderator reacts as Eollows under an influence oE radiation:
2 ~2 2 .... (1) , ~ , D20 ~ 2 2 2 2 ............................. (2) ' Heavy hydrogen D2 and oxygen 2 generated by the reac-tion `; formula (1) are accumulated in a cover gas such as helium.
~ Heavy hydrogen content of the cover gas should be kept below
~ Heavy hydrogen content of the cover gas should be kept below
- 3 molar %, since if the heavy hydrogén content is increased, : - .
. there exists a fear of causing explosion. For this purpose, there has been usually employed a process wherein heavy hydro-;- gen and oxygen in -the cover gas are made to react by the ~ reverse reaction of the formula (1), i.e. by the following I reaction (3j, in the presence of a catalyst comprising a noble ~, ~ metal oE Group VIII in the Periodic Table supported on a ~....................................... .
carrier of a large surface area such as alumina, to thereby recombine heavy hydrogen with oxygen to form heavy water:
D2 + 2 2 ~ D20 ---- (3) ; ~ The reco~bination according to the reaction formula (3) is carried out generally by passing the cover gas containing heavy hydrogen and oxygen through a catalyst bed. However, a part of oxygen formed by reaction (1) is consumed in the production of heavy hydrogen peroxide according to the reaction (2). Therefore, for converting all of heavy hydrogen contained ~' ' ~ ' ~3S"3~
in -the cover ~ras i.nto lleavy wa-ter, .it ls necessary to make up the oxygen balance in the cover ~as prior to -the recombina--~: tion according -to the reaction (3).
ur-ther, if heavy water vapor formed by the recombination according to the reaction (3) is condensed on the surface of the metal catalyst, the catalytic effec-t is deteriorated and, . consequently, reaction velocity is reduced. Therefore, it is required to heat the cover gas !to a temperature of abou-t 70-150C so as to preven-t the condensa-tion of heavy wa-ter vapor on the catalyst sur-Eace. ~ O
On the other hand, heavy hydrogen peroxide ~ formed by the reaction (2) accumulates in the heavy water. Since heavy hydrogen peroxide h.as a strong oxidizing power, i-t oxidizes an ion exchange resin used for.purifying the heavy .~. water to form H2SO~, H2CO3, H20, etc. As a result, the ele-ctric conductivity of the heavy water is increased, the . radiolysis of the heavy water is accelerated to reduce the I ~ heavy water concentration and the heavy water circulation system is corroded. Thus, heavy hydrogen peroxide in the , heavy water must be decomposed con-tinuously according to the followi.ng catalytic reaction (4):
D202 2 + 2 2 ----.(4) :1 In coventional processes, the decomposition of heavy hydrogen peroxide according to the reaction (4) is carried out separately from the recombination of oxygen with heavy hydrogen according to the reaction t3).
An object of the present invention is to provide a process wherein th.e recombination of oxygen wlth heavy hydrogen and ; the decomposition of heavy hydrogen peroxide are effected , ' ~
' .
~13~ V
:, simultaneous:Ly in a single step and wherein -the recombination of oxygen with heavy hydrogen can be carried out efficiently.
According to -the present invention, the recombination o-P oxygen with heavy hydrogen is carried out by allowing a . flow of gas containing oxygen and heavy hydrogen to ascend in ` a reac-tion column charged with a noble me-tal catalyst and allowing a Plow of water containing heavy hydrogen peroxide .; to descend in said reaction column. Thus, both the recombina-.' tion oP oxygen with heavy hydrogen and the decomposition o~ ;`!
heavy hydrogen peroxide are carried out simultaneously in one :~ and the same reaction column.
; Therefore, in the present inven-tion, the oxygen .shortage in the cover gas, which must be externally supplemented in the conventional processes for the recombinatio`n of oxygen with : heavy hydrogen in the cover gas, can be supplied continuously by the decomposi-tion of heavy hydrogen peroxide. Thus, the - recombination according to the reaction (3) can be carried , out efficiently and stoi.chiometrically without the external ; ~ supplementation of oxygen into the cover gas.
~;'! In a preferred embodiment of the present invention, the gas is introduced through the bottom of the reaction column '', ' ~ and discharged through the top thereof and the heavy water is `~ allowed to flow downwardly from the top to the bottom, whereby the ascending flow of the gas is countercurrently con-tacted with the descending flow of the heavy water in the catalyst bed. According to this countercurrent process, the recombina-:, :
: tion of oxygen with heavy hydrogen can be accomplished effecti-vely. The recombination by the reaction (3) is exothermic.
If, for example~ 1 vol. % heavy hydrogen in the cover gas is combined with oxygen, temperature is elevated by about 70C.
~j:
. there exists a fear of causing explosion. For this purpose, there has been usually employed a process wherein heavy hydro-;- gen and oxygen in -the cover gas are made to react by the ~ reverse reaction of the formula (1), i.e. by the following I reaction (3j, in the presence of a catalyst comprising a noble ~, ~ metal oE Group VIII in the Periodic Table supported on a ~....................................... .
carrier of a large surface area such as alumina, to thereby recombine heavy hydrogen with oxygen to form heavy water:
D2 + 2 2 ~ D20 ---- (3) ; ~ The reco~bination according to the reaction formula (3) is carried out generally by passing the cover gas containing heavy hydrogen and oxygen through a catalyst bed. However, a part of oxygen formed by reaction (1) is consumed in the production of heavy hydrogen peroxide according to the reaction (2). Therefore, for converting all of heavy hydrogen contained ~' ' ~ ' ~3S"3~
in -the cover ~ras i.nto lleavy wa-ter, .it ls necessary to make up the oxygen balance in the cover ~as prior to -the recombina--~: tion according -to the reaction (3).
ur-ther, if heavy water vapor formed by the recombination according to the reaction (3) is condensed on the surface of the metal catalyst, the catalytic effec-t is deteriorated and, . consequently, reaction velocity is reduced. Therefore, it is required to heat the cover gas !to a temperature of abou-t 70-150C so as to preven-t the condensa-tion of heavy wa-ter vapor on the catalyst sur-Eace. ~ O
On the other hand, heavy hydrogen peroxide ~ formed by the reaction (2) accumulates in the heavy water. Since heavy hydrogen peroxide h.as a strong oxidizing power, i-t oxidizes an ion exchange resin used for.purifying the heavy .~. water to form H2SO~, H2CO3, H20, etc. As a result, the ele-ctric conductivity of the heavy water is increased, the . radiolysis of the heavy water is accelerated to reduce the I ~ heavy water concentration and the heavy water circulation system is corroded. Thus, heavy hydrogen peroxide in the , heavy water must be decomposed con-tinuously according to the followi.ng catalytic reaction (4):
D202 2 + 2 2 ----.(4) :1 In coventional processes, the decomposition of heavy hydrogen peroxide according to the reaction (4) is carried out separately from the recombination of oxygen with heavy hydrogen according to the reaction t3).
An object of the present invention is to provide a process wherein th.e recombination of oxygen wlth heavy hydrogen and ; the decomposition of heavy hydrogen peroxide are effected , ' ~
' .
~13~ V
:, simultaneous:Ly in a single step and wherein -the recombination of oxygen with heavy hydrogen can be carried out efficiently.
According to -the present invention, the recombination o-P oxygen with heavy hydrogen is carried out by allowing a . flow of gas containing oxygen and heavy hydrogen to ascend in ` a reac-tion column charged with a noble me-tal catalyst and allowing a Plow of water containing heavy hydrogen peroxide .; to descend in said reaction column. Thus, both the recombina-.' tion oP oxygen with heavy hydrogen and the decomposition o~ ;`!
heavy hydrogen peroxide are carried out simultaneously in one :~ and the same reaction column.
; Therefore, in the present inven-tion, the oxygen .shortage in the cover gas, which must be externally supplemented in the conventional processes for the recombinatio`n of oxygen with : heavy hydrogen in the cover gas, can be supplied continuously by the decomposi-tion of heavy hydrogen peroxide. Thus, the - recombination according to the reaction (3) can be carried , out efficiently and stoi.chiometrically without the external ; ~ supplementation of oxygen into the cover gas.
~;'! In a preferred embodiment of the present invention, the gas is introduced through the bottom of the reaction column '', ' ~ and discharged through the top thereof and the heavy water is `~ allowed to flow downwardly from the top to the bottom, whereby the ascending flow of the gas is countercurrently con-tacted with the descending flow of the heavy water in the catalyst bed. According to this countercurrent process, the recombina-:, :
: tion of oxygen with heavy hydrogen can be accomplished effecti-vely. The recombination by the reaction (3) is exothermic.
If, for example~ 1 vol. % heavy hydrogen in the cover gas is combined with oxygen, temperature is elevated by about 70C.
~j:
- 4 -~ .
, ~ 3~
In SUC}l an exothermic reac-tion, it i5 desirable for maintain-ing the ca-talyst l.ife to control -the -temperature elevation as far as possible. Thus, by the countercurrent contact of -the ; heavy water with the gas, the temperature elevation can be ~ suppressed.
In a more preferred embodiment of the present i.nvention, a hydrophobic noble meta]. catalyst is used as the noble metal catalyst to be charged in the reaction column. The hydrophobic , catalyst can be prepared by supporting a noble metal on the ., surface of a hydrophobic carrier such as, for example, poly-tetrafluoroethylene or divinylbenzene styrene copolymer. As the noble metals, there may be used the same metals of Group . VIII in the Periodic Tab:Le as those used in the conventional .~ processes such as platinum, palladium, rhodium and ruthenium.
When such a hydrophobic noble metal catalyst is used, heavy water vapor formed by the recombination of oxygen and ~ .
:1: heavy hydrogen is not condensed on the catalyst surface and, I therefore, the catalytic activity is not deteriorated.
~ Accordingly, heating of the catalyst bed necessitated for pre-.
venting the condensation of heavy water vapor on the catalyst ~: surface in the conventional processes becomes unnecessary and in addition, preheating of the gas to be in-troduced becomes ~!~ also unnecessary.
.. The present invention will be further illustrated by way .~ of the accompanying drawings in which: .
Fig. 1 is a schematic diagram showing a reaction column !
. used in the invention , Fig. 2 is a schematic diagram of a modified bottom portion of Fig. 1 ;
Fig. 3 is a schematic diagram showing another reaction ' :
\
~13~i9~
, colwnn used in an embodiment of -the invention in wllich two catalyst beds are separately provided in the column; and Fig. 4 is a schema-tic diagram showing other reaction column used in an embodiment of the invention in which mul-tiple ca-talyst beds are provided :in the column.
Referring now to Fig. 1, there is shown an example of a preferred reaction column employed Eor practising -the presen-t invention. A gas containing oxygen and heavy hydrogen is in-troduced into the column through a gas-supplying pipe 1. While the gas ascends through a catalyst bed 2, oxygen and heavy hydrogen are recombined together to form heavy-water according to the catalytic effect. The gas is finally discharged from the column through a gas-dischargin~ pipe 3. On the other hand, heavy water containing heavy hydrogen peroxide is introduced into the column through a heavy water-supplying pipe ~ at the top of the column and contacted countercurrently with the Z
ascending gas Elow while it descends in the catalyst bed 2.
During thi.s descending the flow of heavy water cools the heat of reaction generated by the recombination of oxygen with heavy hydrogen, and heavy hydrogen peroxide in the heavy water is -decomposed to generate oxygen and finally discharged through a heavy water-discharging pipe 5 disposed at the bottom of the column. A given quantity of heavy water 6 is always stored at the bottom of the column so that the gas supplied through the gas-supplying pipe 1 would not be directly discharged through the discharging pipe 5 together with the heavy water. In order . ~ .
~; to store the given quantity of heavy water, heavy water supply and heavy water discharge are controlled by valves 7 and 8 and a controller 9. Another controlling device (not shown) may also be providecl in order to control heavy water supply and gas supply in connection with each o-ther so -that the decom-position of heavy hydrogen peroxide and the recombination of oxygen with heavy hydrogen are carried out properly.
As for contro]ling means for s-toring a given quantity of heavy wa-ter at the bottom of the column, there may be employed a method wherein heavy water level is detec-ted by photoelectric cells 10 and 11 and opening degree of the heavy water-discharg-ing valve 8 is controlled by a controller 12 as shown in Fig.
2.
It is desirable to select variety of the noble metal catalysts and modes of the supply of the gas and water depending on the heavy hydrogen content of tlle gas and the heavy hydrogen "
peroxide content of the heavy water to be introduced into the reaction column.
, In the case where the heavy hydrogen content of the gas is relatively high and the heavy hydrogen peroxide content of the heavy water is relatively low, it is preferred to charge ~i a hydrophobic noble metal catalyst in the react:ion column as shown in Fig. 1. In this case, the hydrophobic catalyst is used so as to prevent the condensation of the resulting heavy water vapor on the catalyst surface in order to effect the recombination of oxygen with heavy hydrogen particularly efficiently. The heat of reaction generated by the recombi-`` nation of oxygen and heavy hydrogen can be cooled effectively ~ by the heavy water descending countercurrently to the ascending ~
.~ , -gas fl~ow. Though the decomposition of heavy hydrogen peroxide is accelerated more effectively when a hydrophilic noble metal .:
catalyst is used than a case wherein a hydrophobic noble metal catalyst is used, said decomposition can also be carried out in the presence of a hydrophobic catalyst without being influenced ~3~
.
:.
i. by the recombination wl~en -the heavy hydrogen peroxide con-ten-t of the heavy water is rela-tively low.
In the case wherein both the heavy hydrogen content of the gas and the heavy hydrogen peroxide content of the heavy water are relatively high, it is necessary to carry out both i recombination of oxygen with heavy hydrogen and the decomposi-tion of heavy hydrogen peroxide efficiently. For this purpose, it is preferred to charge a mixture of the hydrophobic noble metal catalys-t and the hydrophilic noble metal caralyst in the ~ reaction column shown in Fig. 1. By using the mixed catalys-t ;` bed, the oxygen/heavy hydrogen recombining reaction and the heavy hydrogen peroxide-decomposing reaction ~can be promoted effectively by the hydrophobic catalyst and the hydrophilic catalyst, respectively.
Also when the heavy hydrogen content of the gas is . ~ .
~, relatively low and the heavy hydrogen peroxide content of the ;, heavy water is relatively high, the effective treatement is made possiblé if the mixed catalyst bed comprising hydrophobic catalyst and hydrophilic catalyst is used. The hydrophilic catalysts have been used heretofore, and can be prepared by supporting noble metals on carriers of a large surface area such . ~, as alumina and diatomaceous earth. ;
In the case where both the heavy hydrogen content of the ' ~ gas and the heavy hydrogen peroxide content of the heavy water l~ are relatively low, a modified method as shown in Fig. 3 can be employed favorably. In an embodiment shown in Fig. 3, a ; hydrophob1c noble metal catalyst bed 21 and a hydr~philic noble metal catalyst bed 22 are placed separately in an upper part and a lower part of a reaction column, respectively, with , leaving a space between the catalyst beds. The gas is introduced :~ - 8 -~L~3!5~
into a center por-tion of the column -through a gas-supplying pipe 23 disposed in a side wall of the column. While the gas ascneds through the hydrophobic catalys-t bed 21, the oxygen/heavy hydrogen recombining reaction is carried ou-t efficiently. The gas is finally discharged -from the column through a gas-discharging pipe 2~ provided at the top of the column. On the other hand, -the heavy water is introduced into the center portion of the column through a heavy water-supply-ing pipe 25 disposed in a side wall of the column. While the heavy water descends through the hydrophilic catalyst bed 22, the heavy hydrogen peroxide-decomposing reaction is carried out efficiently. The heavy water is finally discharged from the column through a heavy water-discharging pipe 26 provided at the bottom of the column. In the embodiment shown in Fig.
3, the countercurrent contact of the descerding flow of heavy water with the ascending flow of gas is not always required, since the heat ~uantity generated by the recombination of heavy hydrogen with oxygen is relatively small because of the relatively low heavy hydrogen content of the gas. However, . : :
like the embodiment shown in Fig. 1, oxygen formed by the decomposition effectively makes up the oxygen deficiency in the ~ recombination, since the oxygen/heavy hydrogen recombining reac-,~ tion and the heavy hydrogen peroxide-decomposing reaction pro-ceed simultaneously in one and the same reaction column.
, ~ If the recombination and the~decomposition are not com-: .
pleted by passing the flows of gas and water through only one hydrophobic catalYst bed and one hydrophilic catalyst bed as ,~, .
shown in Fig. 3, the reactions can be carried out more com-pletely by employing a column of multiple catalyst beds as shown in Fig. 4. In this embodiment, hydrophobic noble metal , ~ .
: ~ - g _ -:
~3~
catalys-t beds 31a and 31b and hydrophilic nob:Le me-tal catalyst beds 32a and 32b are placed alterna-tely and separately Prom one another in the column. A fl,ow of heavy water contaning heavy hydrogen peroxide is introduced through a wa-ter-supply-ing pipe 33 and allowed to descend -through the hydrophilic catalys-t bed 32a. The descending heavy wa-ter is once guided outside the column -through a wa-ter-guiding pipe 34 by means o~
an inclined par-ti-tion 35 and then introduced again in-to a par-t above -the second hydrophilic catalys-t bed 32b and allowed to descend through the catalys-t bed 32b. On the other haDd, the heavy hydrogen-containing gas is introduc~d through a gas-supplying pipe 36 and allowed to ascend through the lower hydrophobic catalyst bed 31a, once guided outside the column through a gas-guiding pipe 37 by the partition 35, then intro-duced again into a part below the second hydrophobic catalyst bed 3lb and allowed to ascend through the catalyst bed 3lb.
In order to prevent the gas introduced into the column through the gas-supplying pipe 36 and the gas-guiding pipe 37 from being directly discharged through the water-guiding pipe 34 and the water-supplying pipe 33, respectively, downstream end por-tions of the water-supplying pipe 33 and -the water-guiding pipe 34 are provided with water seal means (not shown). Though -two hydrophobic catalyst beds and two hydrophilic catalyst beds are provided in the embodiment of Fig. 4, more catalyst beds may be used in one and the same reaction column as a matter of course.
Thus, by providing multiple hydrophobic catalyst beds and hydro-philic catalyst beds alternately in one and the same react1on column, -the recombination and decomposition can be carried out completely in a compact device.
.
, ~ - 1 0 _ , ~ . . .
The foregoing descrip-tion has been made on the recombina-tion of oxygen with heavy hydrogen and the decomposition of heavy hydrogen peroxide contained in heavy water. It will be easily understood, however, that the present invention is also applicable to the recombination of oxygen with hydrogen and the decomposition o~ hydrogen peroxide con-tained in wa-ter.
Example A granular hydrophobic platinum carried on porous poly-tetrafluoroethylene was charged in a co:Lumn of a diameter of Scm to obtain a catalys-t bed of a length of 30 cm. A nonpre-; heated cover gas having the hydrogen content o-f 3 vol. % was introduced through the bottom of the catalyst bed at a flow rate of 1 Nm3/hr. and discharged through -the top of the column.
On the other hand, water containing 10 ppm of hydrogen peroxide was introduced through the top of the catalyst bed at a rate of 2 Kg/hr. and discharged through the bottom. Thus, the ascen-~ ing gas flow was contacted countercurrently with the descending ` water flow. The cover gas discharged through the top had the hydrogen content of less than O;l vol. % and water discharged through the bottom had the hydrogen peroxide content of less than 1 ppm. Temperature elevation in the catalyst bed was less than 50C.
~ It can be seen from the above description of the present i~ invention that the oxygen deficiency in the recombination of "~ oxygen with hydrogen can be made up continuously by oxygen formed by the decomposition of hydrogen peroxide, since the recombination and the decomposition are carried out simulta-neously in one and the same reaction column. Further, the activity of the catalyst is not deteriorated, since the .
. ~ .
~3S~
condensation of wa-ter vapor Eormed by -the recombina-tion on the catalyst surface can be prevented by using the hydroph~bic noble :~ metal catalyst and, therefore, a step of prehea-ting of the gas for the prevention of condensation is not required.
' .
., .
:, . .
.~' ,.
, I , ; :
!, 7,.~ ~ ;
', ,'~ :
"
,''',~ i ; - 12 -:
;~ . . : , ~ . ~:
, ~ 3~
In SUC}l an exothermic reac-tion, it i5 desirable for maintain-ing the ca-talyst l.ife to control -the -temperature elevation as far as possible. Thus, by the countercurrent contact of -the ; heavy water with the gas, the temperature elevation can be ~ suppressed.
In a more preferred embodiment of the present i.nvention, a hydrophobic noble meta]. catalyst is used as the noble metal catalyst to be charged in the reaction column. The hydrophobic , catalyst can be prepared by supporting a noble metal on the ., surface of a hydrophobic carrier such as, for example, poly-tetrafluoroethylene or divinylbenzene styrene copolymer. As the noble metals, there may be used the same metals of Group . VIII in the Periodic Tab:Le as those used in the conventional .~ processes such as platinum, palladium, rhodium and ruthenium.
When such a hydrophobic noble metal catalyst is used, heavy water vapor formed by the recombination of oxygen and ~ .
:1: heavy hydrogen is not condensed on the catalyst surface and, I therefore, the catalytic activity is not deteriorated.
~ Accordingly, heating of the catalyst bed necessitated for pre-.
venting the condensation of heavy water vapor on the catalyst ~: surface in the conventional processes becomes unnecessary and in addition, preheating of the gas to be in-troduced becomes ~!~ also unnecessary.
.. The present invention will be further illustrated by way .~ of the accompanying drawings in which: .
Fig. 1 is a schematic diagram showing a reaction column !
. used in the invention , Fig. 2 is a schematic diagram of a modified bottom portion of Fig. 1 ;
Fig. 3 is a schematic diagram showing another reaction ' :
\
~13~i9~
, colwnn used in an embodiment of -the invention in wllich two catalyst beds are separately provided in the column; and Fig. 4 is a schema-tic diagram showing other reaction column used in an embodiment of the invention in which mul-tiple ca-talyst beds are provided :in the column.
Referring now to Fig. 1, there is shown an example of a preferred reaction column employed Eor practising -the presen-t invention. A gas containing oxygen and heavy hydrogen is in-troduced into the column through a gas-supplying pipe 1. While the gas ascends through a catalyst bed 2, oxygen and heavy hydrogen are recombined together to form heavy-water according to the catalytic effect. The gas is finally discharged from the column through a gas-dischargin~ pipe 3. On the other hand, heavy water containing heavy hydrogen peroxide is introduced into the column through a heavy water-supplying pipe ~ at the top of the column and contacted countercurrently with the Z
ascending gas Elow while it descends in the catalyst bed 2.
During thi.s descending the flow of heavy water cools the heat of reaction generated by the recombination of oxygen with heavy hydrogen, and heavy hydrogen peroxide in the heavy water is -decomposed to generate oxygen and finally discharged through a heavy water-discharging pipe 5 disposed at the bottom of the column. A given quantity of heavy water 6 is always stored at the bottom of the column so that the gas supplied through the gas-supplying pipe 1 would not be directly discharged through the discharging pipe 5 together with the heavy water. In order . ~ .
~; to store the given quantity of heavy water, heavy water supply and heavy water discharge are controlled by valves 7 and 8 and a controller 9. Another controlling device (not shown) may also be providecl in order to control heavy water supply and gas supply in connection with each o-ther so -that the decom-position of heavy hydrogen peroxide and the recombination of oxygen with heavy hydrogen are carried out properly.
As for contro]ling means for s-toring a given quantity of heavy wa-ter at the bottom of the column, there may be employed a method wherein heavy water level is detec-ted by photoelectric cells 10 and 11 and opening degree of the heavy water-discharg-ing valve 8 is controlled by a controller 12 as shown in Fig.
2.
It is desirable to select variety of the noble metal catalysts and modes of the supply of the gas and water depending on the heavy hydrogen content of tlle gas and the heavy hydrogen "
peroxide content of the heavy water to be introduced into the reaction column.
, In the case where the heavy hydrogen content of the gas is relatively high and the heavy hydrogen peroxide content of the heavy water is relatively low, it is preferred to charge ~i a hydrophobic noble metal catalyst in the react:ion column as shown in Fig. 1. In this case, the hydrophobic catalyst is used so as to prevent the condensation of the resulting heavy water vapor on the catalyst surface in order to effect the recombination of oxygen with heavy hydrogen particularly efficiently. The heat of reaction generated by the recombi-`` nation of oxygen and heavy hydrogen can be cooled effectively ~ by the heavy water descending countercurrently to the ascending ~
.~ , -gas fl~ow. Though the decomposition of heavy hydrogen peroxide is accelerated more effectively when a hydrophilic noble metal .:
catalyst is used than a case wherein a hydrophobic noble metal catalyst is used, said decomposition can also be carried out in the presence of a hydrophobic catalyst without being influenced ~3~
.
:.
i. by the recombination wl~en -the heavy hydrogen peroxide con-ten-t of the heavy water is rela-tively low.
In the case wherein both the heavy hydrogen content of the gas and the heavy hydrogen peroxide content of the heavy water are relatively high, it is necessary to carry out both i recombination of oxygen with heavy hydrogen and the decomposi-tion of heavy hydrogen peroxide efficiently. For this purpose, it is preferred to charge a mixture of the hydrophobic noble metal catalys-t and the hydrophilic noble metal caralyst in the ~ reaction column shown in Fig. 1. By using the mixed catalys-t ;` bed, the oxygen/heavy hydrogen recombining reaction and the heavy hydrogen peroxide-decomposing reaction ~can be promoted effectively by the hydrophobic catalyst and the hydrophilic catalyst, respectively.
Also when the heavy hydrogen content of the gas is . ~ .
~, relatively low and the heavy hydrogen peroxide content of the ;, heavy water is relatively high, the effective treatement is made possiblé if the mixed catalyst bed comprising hydrophobic catalyst and hydrophilic catalyst is used. The hydrophilic catalysts have been used heretofore, and can be prepared by supporting noble metals on carriers of a large surface area such . ~, as alumina and diatomaceous earth. ;
In the case where both the heavy hydrogen content of the ' ~ gas and the heavy hydrogen peroxide content of the heavy water l~ are relatively low, a modified method as shown in Fig. 3 can be employed favorably. In an embodiment shown in Fig. 3, a ; hydrophob1c noble metal catalyst bed 21 and a hydr~philic noble metal catalyst bed 22 are placed separately in an upper part and a lower part of a reaction column, respectively, with , leaving a space between the catalyst beds. The gas is introduced :~ - 8 -~L~3!5~
into a center por-tion of the column -through a gas-supplying pipe 23 disposed in a side wall of the column. While the gas ascneds through the hydrophobic catalys-t bed 21, the oxygen/heavy hydrogen recombining reaction is carried ou-t efficiently. The gas is finally discharged -from the column through a gas-discharging pipe 2~ provided at the top of the column. On the other hand, -the heavy water is introduced into the center portion of the column through a heavy water-supply-ing pipe 25 disposed in a side wall of the column. While the heavy water descends through the hydrophilic catalyst bed 22, the heavy hydrogen peroxide-decomposing reaction is carried out efficiently. The heavy water is finally discharged from the column through a heavy water-discharging pipe 26 provided at the bottom of the column. In the embodiment shown in Fig.
3, the countercurrent contact of the descerding flow of heavy water with the ascending flow of gas is not always required, since the heat ~uantity generated by the recombination of heavy hydrogen with oxygen is relatively small because of the relatively low heavy hydrogen content of the gas. However, . : :
like the embodiment shown in Fig. 1, oxygen formed by the decomposition effectively makes up the oxygen deficiency in the ~ recombination, since the oxygen/heavy hydrogen recombining reac-,~ tion and the heavy hydrogen peroxide-decomposing reaction pro-ceed simultaneously in one and the same reaction column.
, ~ If the recombination and the~decomposition are not com-: .
pleted by passing the flows of gas and water through only one hydrophobic catalYst bed and one hydrophilic catalyst bed as ,~, .
shown in Fig. 3, the reactions can be carried out more com-pletely by employing a column of multiple catalyst beds as shown in Fig. 4. In this embodiment, hydrophobic noble metal , ~ .
: ~ - g _ -:
~3~
catalys-t beds 31a and 31b and hydrophilic nob:Le me-tal catalyst beds 32a and 32b are placed alterna-tely and separately Prom one another in the column. A fl,ow of heavy water contaning heavy hydrogen peroxide is introduced through a wa-ter-supply-ing pipe 33 and allowed to descend -through the hydrophilic catalys-t bed 32a. The descending heavy wa-ter is once guided outside the column -through a wa-ter-guiding pipe 34 by means o~
an inclined par-ti-tion 35 and then introduced again in-to a par-t above -the second hydrophilic catalys-t bed 32b and allowed to descend through the catalys-t bed 32b. On the other haDd, the heavy hydrogen-containing gas is introduc~d through a gas-supplying pipe 36 and allowed to ascend through the lower hydrophobic catalyst bed 31a, once guided outside the column through a gas-guiding pipe 37 by the partition 35, then intro-duced again into a part below the second hydrophobic catalyst bed 3lb and allowed to ascend through the catalyst bed 3lb.
In order to prevent the gas introduced into the column through the gas-supplying pipe 36 and the gas-guiding pipe 37 from being directly discharged through the water-guiding pipe 34 and the water-supplying pipe 33, respectively, downstream end por-tions of the water-supplying pipe 33 and -the water-guiding pipe 34 are provided with water seal means (not shown). Though -two hydrophobic catalyst beds and two hydrophilic catalyst beds are provided in the embodiment of Fig. 4, more catalyst beds may be used in one and the same reaction column as a matter of course.
Thus, by providing multiple hydrophobic catalyst beds and hydro-philic catalyst beds alternately in one and the same react1on column, -the recombination and decomposition can be carried out completely in a compact device.
.
, ~ - 1 0 _ , ~ . . .
The foregoing descrip-tion has been made on the recombina-tion of oxygen with heavy hydrogen and the decomposition of heavy hydrogen peroxide contained in heavy water. It will be easily understood, however, that the present invention is also applicable to the recombination of oxygen with hydrogen and the decomposition o~ hydrogen peroxide con-tained in wa-ter.
Example A granular hydrophobic platinum carried on porous poly-tetrafluoroethylene was charged in a co:Lumn of a diameter of Scm to obtain a catalys-t bed of a length of 30 cm. A nonpre-; heated cover gas having the hydrogen content o-f 3 vol. % was introduced through the bottom of the catalyst bed at a flow rate of 1 Nm3/hr. and discharged through -the top of the column.
On the other hand, water containing 10 ppm of hydrogen peroxide was introduced through the top of the catalyst bed at a rate of 2 Kg/hr. and discharged through the bottom. Thus, the ascen-~ ing gas flow was contacted countercurrently with the descending ` water flow. The cover gas discharged through the top had the hydrogen content of less than O;l vol. % and water discharged through the bottom had the hydrogen peroxide content of less than 1 ppm. Temperature elevation in the catalyst bed was less than 50C.
~ It can be seen from the above description of the present i~ invention that the oxygen deficiency in the recombination of "~ oxygen with hydrogen can be made up continuously by oxygen formed by the decomposition of hydrogen peroxide, since the recombination and the decomposition are carried out simulta-neously in one and the same reaction column. Further, the activity of the catalyst is not deteriorated, since the .
. ~ .
~3S~
condensation of wa-ter vapor Eormed by -the recombina-tion on the catalyst surface can be prevented by using the hydroph~bic noble :~ metal catalyst and, therefore, a step of prehea-ting of the gas for the prevention of condensation is not required.
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Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for recombination of oxygen with heavy hydrogen comprising allowing a flow of gas containing oxygen and heavy hydrogen to ascend in a reaction column charged with a noble metal catalyst and allowing a flow of water containing heavy hydrogen peroxide to descend in said reaction column, whereby both the recombination of oxygen with hydrogen and the decomposi-tion of hydrogen peroxide are carried out simultaneously in one and the same reaction column to produce heavy water.
2. The process according to claim 1 wherein the ascend-ing flow of the gas is contacted countercurrently with the descend-ing flow of water.
3. The process according to claim 2 wherein a hydro-phobic noble metal catalyst is used as the noble metal catalyst.
4. The process according to claim 2 wherein a mixture of a hydrophobic noble metal catalyst and a hydrophilic noble metal catalyst is used as the noble metal catalyst.
5. The process according to claim 1 wherein a hydro-phobic noble metal catalyst and a hydrophilic noble metal catalyst are charged separately from each other in an upper part and a lower part of the reaction column, respectively, the flow of gas is allowed to ascend through the hydrophobic noble metal catalyst bed and the flow of water is allowed to descend through the hydro-philic noble metal catalyst bed.
6. The process according to claim 5 wherein the hydro-phobic noble metal catalyst and the hydrophilic noble metal catalyst are charged alternately to form multiple catalyst beds in the reaction column, an inclined partition is placed below the hydrophilic catalyst bed so that the water flow des-cending through the hydrophilic catalyst bed is once guided outside the column and then introduced again into a part above a lower hydrophilic catalyst bed in the column, and the gas flow ascending through the hydrophobic catalyst bed is once guided outside the column by said partition and then intro-duced again into a part below the upper hydrophobic catalyst bed in the column.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP54-33872 | 1979-03-23 | ||
| JP54033872A JPS5943401B2 (en) | 1979-03-23 | 1979-03-23 | How to recombine oxygen and hydrogen |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1135940A true CA1135940A (en) | 1982-11-23 |
Family
ID=12398598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000347053A Expired CA1135940A (en) | 1979-03-23 | 1980-03-05 | Process for recombination of oxygen with hydrogen |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5943401B2 (en) |
| CA (1) | CA1135940A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5082647A (en) * | 1988-10-24 | 1992-01-21 | Atomic Energy Of Canada Limited | Production of hydrogen peroxide |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1141522A (en) * | 1980-11-03 | 1983-02-22 | Karl T. Chuang | Method of combining gaseous hydrogen and oxygen |
| US5160713A (en) * | 1990-10-09 | 1992-11-03 | The Standard Oil Company | Process for separating oxygen from an oxygen-containing gas by using a bi-containing mixed metal oxide membrane |
| JP6656306B2 (en) | 2018-06-08 | 2020-03-04 | 株式会社 資生堂 | Box assembly and packing system and controller for the system |
-
1979
- 1979-03-23 JP JP54033872A patent/JPS5943401B2/en not_active Expired
-
1980
- 1980-03-05 CA CA000347053A patent/CA1135940A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5082647A (en) * | 1988-10-24 | 1992-01-21 | Atomic Energy Of Canada Limited | Production of hydrogen peroxide |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5943401B2 (en) | 1984-10-22 |
| JPS55126502A (en) | 1980-09-30 |
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