JP6191862B2 - Hydrogen-oxygen bond device - Google Patents

Description

  The present invention relates to a hydrogen-oxygen bonding apparatus, and more particularly to a hydrogen-oxygen bonding apparatus for recombining hydrogen and oxygen generated by the decomposition of water.

  In general, a boiling water nuclear power plant is used as a nuclear power plant. In this boiling water nuclear power plant, a fuel containing nuclear fuel material is loaded into a reactor core in a nuclear reactor pressure vessel, and steam is generated by heating cooling water by heat generated by nuclear fission of the nuclear fuel material. The steam generated in this way is supplied to the turbine and used for power generation.

  On the other hand, cooling water may be decomposed into hydrogen (gas) and oxygen (gas) by radiation such as neutrons and gamma rays generated by fission.

  In addition, for example, hydrogen and oxygen may be generated due to equipment failure in addition to the normal operation described above. Specifically, for example, when an accident involving core melting occurs, a large amount of water is decomposed. May produce large amounts of hydrogen and oxygen.

  Furthermore, radioactive waste (including contaminated water) generated in a nuclear power plant is usually sealed in a container and buried in the ground. In the container, water is decomposed by the radioactive waste to generate hydrogen and oxygen. May occur.

  Since such a mixed gas of hydrogen and oxygen is flammable, it is required to recombine hydrogen and oxygen and return them to water from the viewpoint of safety. For example, recombination that recombines hydrogen and oxygen is required. It has been proposed to use a bound catalyst.

  Specifically, for example, a catalyst for recombining hydrogen and oxygen is disposed in the recombination apparatus, and a gas containing hydrogen and oxygen generated in the nuclear reactor is introduced into the recombination apparatus. It has been proposed to obtain water by contacting with a catalyst and recombining hydrogen and oxygen (see, for example, Patent Document 1).

  In addition, for example, it has been proposed to enclose a powdered catalyst together with radioactive waste in a container, and recombine hydrogen and oxygen generated by the decomposition of water by the radioactive waste with the catalyst to generate water. (For example, refer to Patent Document 2).

JP 2011-230064 A JP 2008-298640 A

  However, as described in Patent Document 1 and Patent Document 2, when hydrogen and oxygen are combined to produce water, reaction heat is generated, so the temperature around the catalyst rises and hydrogen ignites. There is a case. Therefore, it is required to suppress hydrogen ignition.

  Accordingly, an object of the present invention is to provide a hydrogen-oxygen bonding apparatus capable of combining hydrogen and oxygen and suppressing the ignition of hydrogen.

  In order to achieve the above object, a hydrogen-oxygen bonding apparatus according to the present invention includes a pass member through which a gas containing hydrogen and oxygen passes, and hydrogen and oxygen that are disposed in the pass member and contacted with the gas. A plurality of catalyst parts including a catalyst for binding the catalyst, and the catalyst parts are arranged along the gas flow direction, and the catalyst parts arranged downstream in the gas flow direction, Compared with the catalyst part arranged on the upstream side in the gas flow direction, more catalyst is provided.

  In the hydrogen-oxygen bonding apparatus of the present invention, a gas containing hydrogen and oxygen is passed through the pass member, and in the catalyst portion arranged in the pass member, is brought into contact with the catalyst, and hydrogen and oxygen are combined.

  In the path member, a plurality of catalyst parts are arranged along the gas flow direction, and a catalyst part arranged downstream of the gas flow direction is arranged upstream of the gas flow direction. Since many catalysts are provided as compared with the catalyst part, it is possible to suppress excessive generation of reaction heat and to suppress hydrogen ignition.

  More specifically, on the upstream side in the gas flow direction in which a large amount of hydrogen and oxygen are present, if they are combined with a relatively large amount of catalyst, an excessive amount of hydrogen and oxygen are combined to excessively generate heat of reaction. This can cause hydrogen to ignite. On the other hand, in the present invention, hydrogen and oxygen are recombined by a relatively small amount of catalyst on the upstream side in the gas flow direction, so that excessive reaction heat can be suppressed and hydrogen ignition is suppressed. be able to.

  In addition, if the amount of catalyst used is reduced in order to suppress hydrogen ignition, the hydrogen-oxygen bonding reaction may not be allowed to proceed efficiently, but in the present invention, on the downstream side in the gas flow direction, Since hydrogen and oxygen are recombined by a large number of catalysts, hydrogen and oxygen can be combined efficiently.

FIG. 1 is a schematic configuration diagram showing an embodiment of the hydrogen-oxygen recombination apparatus of the present invention. FIG. 2 is a schematic configuration diagram showing another embodiment of the hydrogen-oxygen recombination apparatus of the present invention.

  In FIG. 1, a hydrogen-oxygen bonding apparatus 1 includes a path member 2 through which a gas containing hydrogen and oxygen passes, and a catalyst member 3 as a plurality of (for example, three) catalyst portions disposed in the path member 2. A plurality of (for example, two) flame extinguishing members 4 are provided.

  The path member 2 is, for example, a cylindrical member extending in the longitudinal direction, and a gas containing hydrogen and oxygen (hereinafter simply referred to as a gas) is allowed to pass therethrough, and the gas is guided toward the catalyst member 3 (guide). ) Is provided. The size (inner diameter, longitudinal length, etc.) of the pass member 2 is appropriately set according to the purpose and application.

  As will be described in detail later, as shown by an arrow in FIG. 1, a gas containing hydrogen and oxygen is supplied from the lower side to the upper side of the paper.

  The plurality (three) of the catalyst members 3 are formed, for example, so that the outermost shape is a cylindrical shape, and are arranged so as to share the central axis with the pass member 2 by a fixing member (not shown). 2 are fixed to each other at a predetermined interval. Thereby, the plurality (three) of the catalyst members 3 are arranged in parallel along the gas flow direction.

  In the following description, when it is necessary to distinguish each catalyst member 3, the first catalyst member 3a and the second catalyst member 3b are sequentially arranged from the upstream side (the lower side in the drawing) in the gas flow direction (arrow in FIG. 1). And the third catalyst member 3c.

  A plurality (three) of the catalyst members 3 are each formed as a coating layer on the surface of the open cell of the catalyst support 5 and the catalyst support 5 formed of a porous member in which a large number of open cells penetrating in the gas flow direction are formed. And a catalyst 6 to be formed.

  The catalyst carrier 5 is formed of a honeycomb monolith carrier made of, for example, cordierite. Similar to the pass member 2, the size of the catalyst carrier 5 is appropriately set according to the purpose and application. For example, when the outermost shape of the catalyst carrier 5 is cylindrical, the outer diameter is formed to be approximately the same as the inner diameter of the path member 2. Although not shown in the drawings, the catalyst carrier 5 is not limited to the monolith carrier described above, and a known catalyst carrier such as a metal substrate can be used.

  The catalyst 6 is a hydrogen-oxygen bond catalyst for combining hydrogen gas and oxygen gas to generate water, and is disposed on the catalyst carrier 5 so as to be in contact with the gas in the path member 2. Has been.

  Examples of the catalyst 6 include a hydrogen-oxygen bond catalyst containing a perovskite complex oxide containing a noble metal and alumina and / or a ceria-based complex oxide.

  The perovskite complex oxide is represented, for example, by the following general formula (1).

_{A x B y O 3 ± δ} (1)
(In the formula, A represents at least one element selected from rare earth elements and alkaline earth metals, B represents at least one element selected from transition elements excluding precious metals and Al, and x represents x. , 0.8 represents an atomic ratio in the numerical range of x ≦ 1.3, y represents an atomic ratio of 1.0, and δ represents an oxygen excess or oxygen deficiency.)
In the perovskite complex oxide in the general formula (1), A is coordinated to the A site and B is coordinated to the B site.

  In the general formula (1), examples of the rare earth element represented by A include Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm ( Promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu ( Lutetium).

  Examples of the alkaline earth metal represented by A include Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium), and Ra (radium). These may be used alone or in combination of two or more.

  These may be used alone or in combination of two or more.

  In the A site of the general formula (1), x is 0.8 ≦ x ≦ 1.3, preferably 0.95 ≦ x ≦ 1.3, and more preferably 1.00 ≦ x ≦ 1. The atomic ratio of A in the numerical range of 30 is shown.

  In the general formula (1), as transition elements excluding the noble metal represented by B, for example, in the periodic table (IUPAC, 1990), atomic number 21 (Sc) to atomic number 30 (Zn), atomic number 39 ( Y) to atomic number 48 (Cd), atomic number 57 (La) to atomic number 80 (Hg), and each element having atomic number 89 (Ac) or more (but noble metals (atomic numbers 44 to 47 and 76 to 78) )). These may be used alone or in combination of two or more.

  Moreover, in General formula (1), the atomic ratio of B shown by y is 1.0.

  In the general formula (1), δ represents an oxygen excess or oxygen deficiency and is represented by 0 or a positive number. More specifically, oxygen generated by excessive or insufficient elements coordinated at the A site with respect to the theoretical composition ratio of the perovskite type complex oxide, A: B: O = 1: 1: 3. The ratio of excess or deficient atoms is shown.

  Such a perovskite complex oxide is not particularly limited, and for example, for preparing a complex oxide in accordance with the description of paragraph numbers [0039] to [0059] of JP-A-2004-243305. It can be produced by an appropriate method, for example, a production method such as a coprecipitation method, a citric acid complex method, or an alkoxide method.

  In the catalyst 6, the perovskite complex oxide contains a noble metal. Specific examples of such a perovskite complex oxide include a perovskite complex oxide supporting a noble metal and a perovskite complex oxide containing a noble metal as a composition.

  The perovskite complex oxide supporting a noble metal is represented by the following general formula (2).

_{N / A x B y O 3} ± δ (2)
(In the formula, N represents at least one element selected from noble metals, A represents at least one element selected from rare earth elements and alkaline earth metals, and B represents a transition element excluding noble metals. And at least one element selected from Al, x represents an atomic ratio in a numerical range of 0.8 ≦ x ≦ 1.3, y represents an atomic ratio of 1.0, and δ represents Indicates oxygen excess or oxygen deficiency.)
In the general formula (2), examples of the noble metal represented by N include Ru (ruthenium), Rh (rhodium), Pd (palladium), Ag (silver), Os (osmium), Ir (iridium), and Pt (platinum). ) And the like. Preferably, Rh, Pd, and Pt are mentioned. These may be used alone or in combination of two or more.

  In the general formula (2), the rare earth element and alkaline earth metal represented by A, the transition element excluding the noble metal represented by B, and Al may be the same as described above.

  In the general formula (2), x, y and δ have the same meaning as the above x, y and δ.

  Such a perovskite-type composite oxide carrying a noble metal is, for example, a perovskite-type composite oxide represented by the general formula (1) produced by the method described above, paragraph No. [0063] of JP-A-2004-243305. ], It can be produced by supporting a noble metal.

  The amount of noble metal supported on the perovskite complex oxide thus obtained is usually 20 parts by mass or less, preferably 0.2 to 5 masses per 100 parts by mass of the perovskite complex oxide, for example. Part.

  On the other hand, a perovskite complex oxide containing a noble metal as a composition is represented by the following general formula (3).

A _x B _1-z N _z O _{3 ± δ} (3)
(In the formula, A represents at least one element selected from rare earth elements and alkaline earth metals, B represents at least one element selected from transition elements excluding noble metals and Al, and N represents , X represents at least one element selected from noble metals, x represents an atomic ratio in a numerical range of 0.8 ≦ x ≦ 1.3, and z represents an atom of 0 <z ≦ 0.5. (Where δ represents oxygen excess or oxygen deficiency)
In the perovskite complex oxide in the general formula (3), A is coordinated to the A site, and B and N are coordinated to the B site.

  In addition, in the general formula (3), the rare earth element and alkaline earth metal represented by A, the transition element excluding the noble metal represented by B, and the noble metal represented by Al and N may be the same as described above.

  In the general formula (2), x and δ have the same meanings as x and δ.

  In the general formula (3), the atomic ratio of N represented by z is, for example, in the range of 0 <z ≦ 0.5, and preferably in the range of 0 <z ≦ 0.2. When z exceeds 0.5, the noble metal represented by N may be difficult to dissolve, and cost increases are unavoidable.

  In the general formula (3), the atomic ratio of B represented by 1-z is, for example, in a range of 0.5 ≦ 1-z <1, and preferably in a range of 0.8 ≦ 1-z <1. is there.

  Such a perovskite type complex oxide containing a noble metal as a composition is manufactured, for example, in accordance with the description of paragraph numbers [0039] to [0059] of JP-A-2004-243305 as described above. Can do.

  The content of the noble metal in the thus obtained perovskite complex oxide is usually 20 parts by mass or less, preferably 0.2 to 5 masses per 100 parts by mass of the perovskite complex oxide, for example. Part.

  The perovskite complex oxide containing the noble metal as a composition can be further loaded with the noble metal as described above.

  Of the above-described perovskite complex oxides, perovskite complex oxides containing a noble metal as a composition are preferably used.

  Examples of alumina include α-alumina, θ-alumina, and γ-alumina, and preferably θ-alumina.

  α-alumina has an α-phase as a crystal phase, and examples thereof include AKP-53 (trade name, high-purity alumina, manufactured by Sumitomo Chemical Co., Ltd.). Such α-alumina can be obtained by a method such as an alkoxide method, a sol-gel method, or a coprecipitation method.

  θ-alumina is a kind of intermediate (transition) alumina that has a θ-phase as a crystal phase and transitions to α-alumina, and includes, for example, SPHERALITE 531P (trade name, γ-alumina, manufactured by Procatalyze). . Such θ-alumina can be obtained, for example, by subjecting commercially available activated alumina (γ-alumina) to heat treatment at 900 to 1100 ° C. for 1 to 10 hours in the air.

  γ-alumina has a γ-phase as a crystal phase and is not particularly limited, and examples thereof include known ones.

  In addition, alumina containing La and / or Ba can also be used. Alumina containing La and / or Ba can be produced according to the description in paragraph [0073] of JP-A No. 2004-243305.

  These aluminas can carry a noble metal. Alumina on which a noble metal is supported can be produced, for example, by supporting a noble metal on the above-mentioned alumina in accordance with the description of paragraph numbers [0122] and [0126] of JP-A-2004-243305. .

  The amount of the noble metal supported in the alumina thus obtained (when a plurality of noble metals are supported, the total amount) is typically 0.01 to 5 parts by mass with respect to 100 parts by mass of alumina, for example. Preferably, it is 0.02-2 mass parts.

  The ceria-based composite oxide is represented, for example, by the following general formula (4).

Ce _{1- (a + b)} Zr _a L _b O _2-c (4)
(In the formula, L represents an alkaline earth metal and / or rare earth element (excluding Ce), a represents the atomic ratio of Zr, b represents the atomic ratio of L, and 1- ( a + b) indicates the atomic ratio of Ce, and c indicates the amount of oxygen defects.)
In the general formula (4), examples of the alkaline earth metal and / or rare earth element represented by L include the same alkaline earth metals and rare earth elements as those described above (excluding Ce). The alkaline earth metal is preferably Mg, Ca, Sr, or Ba, and the rare earth element is preferably Sc, Y, La, Pr, or Nd. These alkaline earth metals and rare earth elements may be used alone or in combination of two or more.

  Further, the atomic ratio of Zr represented by a is in the range of 0.2 to 0.7, and preferably in the range of 0.2 to 0.5.

  In addition, the atomic ratio of L represented by b is in the range of 0 to 0.2 (that is, L is an optional component that is arbitrarily included rather than an essential component, and if included, 0.2 or less) Atomic ratio). If it exceeds 0.2, phase separation or other complex oxide phases may be generated.

  The atomic ratio of Ce represented by 1- (a + b) is in the range of 0.3 to 0.8, and preferably in the range of 0.3 to 0.6.

  Furthermore, c represents the amount of oxygen defects, which means the proportion of vacancies formed in the crystal lattice of the fluorite-type crystal lattice that is normally formed by Ce, Zr and L oxides.

  Such a ceria-based composite oxide is not particularly limited. For example, according to the description of paragraph numbers [0090] to [0102] and [0109] of JP-A-2004-243305, It can be produced by an appropriate method for preparation, for example, a production method such as a coprecipitation method, a citric acid complex method, or an alkoxide method.

  Such a ceria-based composite oxide supports the above-mentioned noble metal or can be contained as a composition.

  The ceria-based composite oxide supporting a noble metal is represented by the following general formula (5).

N / Ce _{1- (a + b)} Zr _a L _b O _2-c (5)
(In the formula, L represents an alkaline earth metal and / or rare earth element (excluding Ce), N represents a noble metal, a represents an atomic ratio of Zr, and b represents an L atom. 1- (a + b) indicates the atomic ratio of Ce, and b indicates the amount of oxygen defects.)
In the above formula (5), examples of the noble metal represented by N include the aforementioned noble metals. These noble metals can be used alone or in combination of two or more.

  Such a ceria-based composite oxide loaded with a noble metal is, for example, added to the ceria-based composite oxide represented by the general formula (4) produced by the method described above in paragraph No. [ [0122] In accordance with the description of [0125], it can be produced by supporting a noble metal.

  The supported amount of the noble metal of the ceria-based composite oxide thus obtained is usually 0.01 to 5 parts by weight, preferably 0.02 with respect to 100 parts by weight of the ceria-based composite oxide, for example. ˜2 parts by mass.

  On the other hand, a ceria-based composite oxide containing a noble metal as a composition is represented by the following general formula (6).

Ce _{1- (d + e + f)} Zr _d L _e N _f O _2-g (6)
(In the formula, L represents an alkaline earth metal and / or rare earth element (excluding Ce), N represents a noble metal, d represents the atomic ratio of Zr, and e represents an L atom. (The ratio indicates the atomic ratio of N, 1- (d + e + f) indicates the atomic ratio of Ce, and g indicates the amount of oxygen defects.)
The atomic ratio of Zr represented by d is in the range of 0.2 to 0.7, and preferably in the range of 0.2 to 0.5.

  In addition, the atomic ratio of L represented by e is in the range of 0 to 0.2 (that is, L is an optional component that is optionally included rather than an essential component, and if included, 0.2 or less) Atomic ratio). If it exceeds 0.2, phase separation or other complex oxide phases may be generated.

  Moreover, the atomic ratio of N shown by f is the range of 0.001-0.3, Preferably, it is the range of 0.001-0.2.

  Moreover, the atomic ratio of Ce shown by 1- (d + e + f) is in the range of 0.3 to 0.8, and preferably in the range of 0.4 to 0.6.

  Further, g represents the amount of oxygen defects, which means the ratio of vacancies formed in the crystal lattice of the fluorite-type crystal lattice that is normally formed by Ce, Zr, L, and N oxides.

  For example, as described above, the ceria-based composite oxide containing such a noble metal as a composition conforms to the description of paragraphs [0090] to [0102] and [0109] of JP-A-2004-243305. And can be manufactured.

  In addition, a noble metal can be further supported on the ceria-based composite oxide containing the noble metal as a composition as described above.

  The content of the noble metal of the ceria-based composite oxide thus obtained (the total amount of the supported noble metal and the noble metal contained as a composition) is, for example, 100 parts by weight of the ceria-based composite oxide. Usually, it is 0.01-5 mass parts, Preferably, it is 0.02-2 mass parts.

  In the catalyst 6, the blending ratio of the perovskite-type composite oxide containing the noble metal and the alumina and / or ceria-based composite oxide is such that the alumina and / or the perovskite-type composite oxide containing noble metal is 100 parts by mass. The ceria-based composite oxide (the total amount when used together) is, for example, 50 parts by mass or more, preferably 100 parts by mass or more, for example, 6000 parts by mass or less, preferably 3000 parts by mass or less. It is.

  When alumina and ceria-based composite oxide are used in combination, the blending ratio of ceria-based composite oxide is, for example, 10 parts by weight or more, preferably 20 parts by weight with respect to 100 parts by weight of alumina. Part or more, for example, 500 parts by mass or less, preferably 200 parts by mass or less.

  More specifically, alumina is, for example, 50 parts by mass or more, preferably 100 parts by mass or more, for example, 6000 parts by mass or less, preferably 100 parts by mass of the perovskite complex oxide containing noble metal. Is 3000 parts by mass or less, and the ceria-based composite oxide is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, for example, 5000 parts by mass or less, preferably 2000 parts by mass or less.

  Further, the catalyst 6 can further contain other heat-resistant oxides, specifically, for example, perovskite-type complex oxides that do not contain noble metals, zirconia-based complex oxides, and the like.

  Examples of the perovskite complex oxide not containing a noble metal include the perovskite complex oxide represented by the general formula (1).

  The zirconia composite oxide is represented by the following general formula (7).

_{Zr 1- (h + i) Ce} h R i O 2-j (7)
(In the formula, R represents an alkaline earth metal and / or rare earth element (excluding Ce), h represents the atomic ratio of Ce, i represents the atomic ratio of R, and 1- ( h + i) represents the atomic ratio of Zr, and j represents the amount of oxygen defects.)
In the general formula (7), examples of the alkaline earth metal and / or rare earth element represented by R include the same alkaline earth metals and rare earth elements as those described above (excluding Ce). These rare earth elements and alkaline earth metals can be used alone or in combination of two or more.

  Moreover, the atomic ratio of Ce shown by h is in the range of 0.1 to 0.65, and preferably in the range of 0.1 to 0.5.

  In addition, the atomic ratio of R represented by i is in the range of 0 to 0.55 (that is, R is an optional component that is optionally included rather than an essential component, and if included, 0.55 or less) Atomic ratio). If it exceeds 0.55, phase separation or other complex oxide phases may be generated.

  Moreover, the atomic ratio of Zr shown by 1- (h + i) is in the range of 0.35 to 0.9, and preferably in the range of 0.5 to 0.9.

  Further, j represents the amount of oxygen defects, which means the ratio of vacancies formed in the crystal lattice of the fluorite-type crystal lattice that is usually formed by oxides of Zr, Ce, and R.

  Such a zirconia composite oxide is not particularly limited, and can be manufactured by a manufacturing method similar to the above-described method for manufacturing a ceria composite oxide.

  Such a zirconia-based composite oxide supports a noble metal or can be contained as a composition.

  A zirconia-based composite oxide carrying a noble metal is represented by the following general formula (8).

_{N / Zr 1- (h + i} ) Ce h R i O 2-j (8)
(In the formula, R represents an alkaline earth metal and / or rare earth element (excluding Ce), N represents a noble metal, h represents an atomic ratio of Ce, and i represents an R atom. 1- (h + i) indicates the atomic ratio of Zr, and j indicates the amount of oxygen defects.)
Such a noble metal-supported zirconia-based composite oxide is, for example, a method for supporting the above-mentioned ceria-based composite oxide on a zirconia-based composite oxide represented by the general formula (7) manufactured by the above-described method. It can be produced by supporting a noble metal by the same method as described above.

  The amount of the noble metal supported on the zirconia composite oxide thus obtained is usually 0.01 to 5 parts by mass, preferably 0.02 with respect to 100 parts by mass of the zirconia composite oxide, for example. ˜2 parts by mass.

  On the other hand, a zirconia composite oxide containing a noble metal as a composition is represented by the following general formula (9).

Zr _{1- (k + l + m)} Ce _k R _l N _m O _2-n (9)
(In the formula, R represents an alkaline earth metal and / or rare earth element (excluding Ce), N represents a noble metal, k represents an atomic ratio of Ce, and l represents an R atom. (The ratio indicates the atomic ratio of N, 1- (k + 1 + m) indicates the atomic ratio of Zr, and c indicates the amount of oxygen defects.)
The atomic ratio of Ce represented by k is in the range of 0.1 to 0.65, and preferably in the range of 0.1 to 0.5.

In addition, the atomic ratio of R represented by l is in the range of 0 to 0.55 (that is, R is an optional component that is optionally included rather than an essential component, and if included, 0.55 or less) Atomic ratio). If it exceeds 0.55, phase separation or other complex oxide phases may be generated.
Moreover, the atomic ratio of N shown by m is the range of 0.001-0.3, Preferably, it is the range of 0.001-0.2.

  Further, the atomic ratio of Zr represented by 1- (k + 1 + m) is in the range of 0.35 to 0.9, and preferably in the range of 0.5 to 0.9.

  Further, n represents the amount of oxygen defects, which means the ratio of vacancies formed in the crystal lattice of the fluorite-type crystal lattice normally formed by oxides of Zr, Ce and R.

  Such a zirconia composite oxide containing a noble metal as a composition can be produced, for example, by the same production method as the above-described method for producing a ceria composite oxide containing a noble metal as a composition.

  In addition, a noble metal can be further supported on the zirconia composite oxide containing the noble metal as a composition as described above.

  The content of the noble metal of the zirconia composite oxide thus obtained (the total amount of the supported noble metal and the noble metal contained as a composition) is, for example, 100 parts by mass of the zirconia composite oxide. Usually, it is 0.01-5 mass parts, Preferably, it is 0.02-2 mass parts.

  In the present invention, the Ce atomic ratio of the ceria-based composite oxide represented by the general formulas (4) to (6) is the same as that of the zirconia-based composite oxide represented by the general formulas (7) to (9). When overlapping with the atomic ratio, in the present invention, the overlapping zirconia composite oxide belongs to the ceria composite oxide.

Further, the catalyst 6 can further contain Ba, Ca, Sr, Mg, La sulfate, carbonate, nitrate and / or acetate. Of these salts, BaSO ₄ is preferably used.

  The content ratios of these perovskite complex oxides, zirconia complex oxides, sulfates, carbonates, nitrates, acetates, etc. that do not contain these precious metals are not particularly limited, and are appropriately set depending on the necessity and application. The

  Since such a catalyst 6 includes a perovskite complex oxide containing a noble metal and alumina and / or ceria-based complex oxide, hydrogen and oxygen can be combined and reacted at a relatively low temperature.

Specifically, the reaction start temperature of the catalyst 6 (the temperature of the sample piece when the conversion rate of H ₂ reaches 10%) is, for example, 80 ° C. or more, preferably 90 ° C. or more. 140 ° C. or lower, preferably 135 ° C. or lower.

  The catalyst 6 is preferably subjected to a reduction treatment.

As the reduction treatment, for example, the catalyst 6 may be reduced and calcined. Specifically, in a reducing atmosphere (for example, H ₂ —N ₂ mixed gas (H ₂ concentration 1 to 10%)), for example, For example, at 600 ° C. or more, preferably 800 ° C. or more, for example, 1000 ° C. or less, preferably 900 ° C. or less, for example, 0.1 hour or more, preferably 0.5 hour or more, for example, 10 hours or less, Preferably, baking is performed for 5 hours or less.

  Thereby, the catalyst 6 can be reduced and the reactivity can be improved.

Specifically, the reaction start temperature of the catalyst 6 after the reduction treatment (the temperature of the sample piece when the conversion rate of H ₂ reaches 10%) is, for example, 15 ° C. or higher, preferably 20 ° C. or higher. For example, it is 90 ° C. or lower, preferably 85 ° C. or lower.

  That is, according to such a reduction-treated catalyst 6, hydrogen and oxygen can be combined and reacted from a lower temperature state, for example, hydrogen and oxygen can be combined without generating heat to generate water. can do.

  The catalyst 6 is not limited to the catalyst 6 described above, and a known hydrogen-oxygen bond catalyst as described in, for example, Japanese Patent Application Laid-Open No. 2011-230064 and Japanese Patent Application Laid-Open No. 2008-298640 is used. You can also

  In order to form the catalyst 6 on the surface of the open cell of the catalyst carrier 5 as a coating layer, for example, first, the above-described components are mixed and water is added to form a slurry. The surface is coated, dried at 50 to 200 ° C. for 1 to 48 hours, and further fired at 350 to 1000 ° C. for 1 to 12 hours. Moreover, after adding water to each above-mentioned component to make a slurry, these slurries are mixed, coated on a catalyst carrier, dried at 50 to 200 ° C. for 1 to 48 hours, and further at 350 to 1000 ° C. It can also be fired for 1 to 12 hours.

  As a result, the catalyst 6 can be supported on the surface of the open cell of the catalyst carrier 5 and the catalyst member 3 can be obtained.

  In the hydrogen-oxygen bonding apparatus 1, the catalyst member 3 disposed on the downstream side in the gas flow direction includes a larger number of catalysts 6 than the catalyst member 3 disposed on the upstream side in the gas flow direction. .

  Specifically, the amount of catalyst 6 of the first catalyst member 3a arranged on the most upstream side in the gas flow direction is larger than that of the other catalyst members 3 (second catalyst member 3b and third catalyst member 3c). Designed to minimize the amount of catalyst 6.

  Moreover, the 2nd catalyst member 3b arrange | positioned 2nd from an upstream is designed so that many catalysts 6 may be provided rather than the catalyst 6 quantity of the 1st catalyst member 3a.

  Further, the amount of catalyst 6 of the third catalyst member 3c arranged on the most downstream side is such that the amount of catalyst 6 is the largest compared to the other catalyst members 3 (first catalyst member 3a and second catalyst member 3b). Designed to.

  As described above, the hydrogen-oxygen bonding apparatus 1 is designed so that the amount of the catalyst 6 of each catalyst member 3 increases sequentially from the upstream side to the downstream side in the gas flow direction.

  Specifically, in two catalyst members 3 adjacent to each other in the gas passage direction, the amount of catalyst 6 in the downstream catalyst member 3 exceeds 100 mass% with respect to the amount of catalyst 6 in the upstream catalyst member 3. For example, it is 120% by mass or more, preferably 150% by mass or more, more preferably 200% by mass or more, and usually 1000% by mass or less.

  If the amount of the catalyst 6 is in the above range, excessive reaction heat can be suppressed, and hydrogen ignition can be suppressed.

  The amount of catalyst 6 in each catalyst member 3 is appropriately set according to the purpose and application.

  When three or more catalyst members 3 are used, the difference in the amount of the catalyst 6 between the catalyst members 3 adjacent to each other in the gas flow direction is not particularly limited, and is appropriately set according to the purpose and application. .

  Specifically, for example, the difference in the amount of catalyst 6 between the adjacent catalyst members 3 is the same, and the amount of catalyst 6 in each catalyst member 3 becomes regular (from the upstream side to the downstream side in the gas flow direction) For example, the difference in the amount of catalyst 6 between adjacent catalyst members 3 is different from each other, and the amount of catalyst 6 in each catalyst member 3 is upstream in the gas flow direction. It may be designed so that it increases irregularly as it goes downstream from. Specifically, the difference in the amount of catalyst 6 between the upstream catalyst members 3 in the gas flow direction may be designed to be greater than the difference in the amount of catalyst 6 between the downstream catalyst members 3. It is also possible to design the difference in the amount of the catalyst 6 between the upstream catalyst members 3 to be smaller than the difference in the amount of the catalyst 6 between the downstream catalyst members 3.

  Further, if at least two catalyst members 3 designed so that the amount of catalyst 6 on the downstream side in the gas flow direction is larger than that on the upstream side, for example, the amount of catalyst member 3 on the upstream side and the amount of catalyst 6 are provided. However, the same amount of the catalyst member 3 can be disposed further upstream, and the downstream catalyst member 3 and the catalyst member 3 having the same amount of the catalyst 6 can be disposed further downstream.

  Further, although not shown, as the plurality of catalyst members 3, for example, the catalyst 6 powder may be used as it is without using the catalyst carrier 5. For example, the catalyst 6 may be formed into an arbitrary predetermined shape by a known method. You may shape | mold and use. In such a case, the plurality of catalyst members 3 are arranged and fixed in the path member 2 by a known fixing member (not shown). Even in such a case, similarly to the above, the plurality of catalyst members 3 are designed so that the amount of the catalyst 6 gradually increases from the upstream side to the downstream side in the gas flow direction.

  Two flame extinguishing members 4 are provided in the path member 2, and are arranged upstream and downstream in the gas flow direction (see arrows in FIG. 1) with respect to the catalyst member 3. More specifically, one flame extinguishing member 4 is disposed further upstream than the most upstream first catalyst member 3a, and the other flame extinguishing member 4 is further further than the most downstream third catalyst member 3c. Arranged downstream. Accordingly, the two flame extinguishing members 4 are provided as a pair so as to sandwich all the catalyst members 3, and are opposed to each other along the gas flow direction at a predetermined interval from the upstream and downstream catalyst members 3. Is arranged.

  Such a flame extinguishing member 4 is formed, for example, from a porous member in which a large number of open cells 8 penetrating in the gas flow direction are formed.

  In addition, the opening cell 8 is opened so that gas can pass through, and the shape thereof is not particularly limited, and is appropriately designed according to the purpose and application such as a circular shape or a polygonal shape.

  Moreover, the opening size (opening cross-sectional area) of the open cell 8 may be uniform in the gas passage direction, or may be an opening size (opening cross-sectional area) that is at least partially different.

  A flame extinguishing region is defined in the opening cell 8 of the flame extinguishing member 4.

  The flame extinguishing region is a region for exhibiting a flame extinguishing function when hydrogen is ignited around the catalyst member 3 and has a predetermined opening cross-sectional area (a direction orthogonal to the gas flow direction) in the opening cell 8. Is divided as a portion of the cross-sectional area in FIG.

  Specifically, for example, when the opening size (opening cross-sectional area) of the opening cell 8 is uniform over the entire length (the total length in the direction along the gas flow direction), all the portions of the opening cell 8 are the extinguishing regions. Is done. In addition, when the opening size (opening cross-sectional area) of the open cell 8 is not uniform, a portion of the predetermined open cross-sectional area in the open cell 8 is set as a flame extinguishing region.

Specifically, the opening cross-sectional area (cross-sectional area in the direction orthogonal to the gas flow direction) of the flame extinguishing region is, for example, 0.3 mm ² or less, preferably 0.15 mm ² or less, and is usually 0. 1 mm ² or more.

  If the opening cross-sectional area of the flame extinguishing region is in the above range, the gas can be allowed to pass satisfactorily, and even when hydrogen is ignited by the reaction heat of the catalyst 6 in the catalyst member 3, the flame can be extinguished quickly.

  The shape of the flame extinguishing region is not particularly limited, and is appropriately designed according to the purpose and application, such as a circular shape or a polygonal shape.

  Such a porous member is not particularly limited, and examples thereof include a honeycomb monolith support made of cordierite similar to the catalyst support 5 described above, a metal mesh member, and the like. Preferably, the catalyst support 5 and Similar monolithic carriers are mentioned.

  If a monolithic carrier similar to the catalyst carrier 5 is used as the porous member, the number of types of members can be reduced, so that the cost can be reduced.

  The size of the flame extinguishing member 4 is set as appropriate according to the purpose and application, as with the pass member 2. For example, when the outermost shape of the flame-extinguishing member 4 is a cylindrical shape, the outer diameter is formed to be substantially the same as the inner diameter of the path member 2 and is arranged so as to share the center axis with the path member 2.

  Although not shown, the flame extinguishing member 4 is not limited to the above, and a known extinguishing member can be used.

  Such a hydrogen-oxygen bonding apparatus 1 is arranged so that the longitudinal direction of the path member 2 is along the vertical direction from the viewpoint of the coupling efficiency between hydrogen and oxygen, and hydrogen and oxygen are supplied from below the vertical direction. The contained gas is supplied.

  That is, in this hydrogen-oxygen bonding apparatus 1, when hydrogen and oxygen are combined, there is a case where heating is performed to the reaction start temperature of the catalyst member 3 (catalyst 6) described above. In addition, reaction heat is generated during the bonding reaction between hydrogen and oxygen. Therefore, an upward flow is generated in the path member 2.

  As a result, by arranging the longitudinal direction of the path member 2 along the vertical direction and supplying a gas containing hydrogen and oxygen from below the vertical direction, the gas can be efficiently transported, It is possible to improve the binding efficiency with oxygen.

  In such a hydrogen-oxygen bonding apparatus 1, when a gas containing hydrogen and oxygen is supplied, the gas passes through the path member 2, and the catalyst 6 is disposed in the catalyst member 3 disposed in the path member 2. Contacted with. Thereby, hydrogen and oxygen are combined to produce water.

  Thereby, the explosion accident by the mixed gas (flammable gas) of hydrogen and oxygen can be prevented.

  On the other hand, when hydrogen and oxygen are combined by this hydrogen-oxygen bonding apparatus 1 to produce water, reaction heat is generated, and therefore the temperature around the catalyst member 3 rises and hydrogen may ignite. is there. Therefore, it is required to suppress hydrogen ignition.

  In this regard, in the hydrogen-oxygen bonding apparatus 1 described above, a plurality of catalyst members 3 are arranged in the path member 2 along the gas flow direction and are arranged downstream of the gas flow direction. Compared with the catalyst member 3 disposed on the upstream side in the gas flow direction, the member 3 includes a larger number of catalysts 6, so that excessive reaction heat can be suppressed and hydrogen ignition can be suppressed. be able to.

  More specifically, on the upstream side in the flow direction of the gas in which a large amount of hydrogen and oxygen are present, if they are combined by a relatively large amount of the catalyst 6, an excessive amount of hydrogen and oxygen are combined to cause excessive reaction heat. May cause hydrogen to ignite.

  On the other hand, in the hydrogen-oxygen bonding apparatus 1 described above, since hydrogen and oxygen are recombined by a relatively small amount of the catalyst 6 on the upstream side in the gas flow direction, it is possible to suppress the generation of excessive reaction heat. , Hydrogen ignition can be suppressed.

  Further, if the amount of the catalyst 6 used is reduced in order to suppress the ignition of hydrogen, the hydrogen-oxygen bonding reaction may not be allowed to proceed efficiently. However, in the hydrogen-oxygen bonding apparatus 1 described above, Since hydrogen and oxygen are recombined by a relatively large number of catalysts 6 on the downstream side in the flow direction, hydrogen and oxygen can be combined efficiently.

  In the hydrogen-oxygen bonding apparatus 1 described above, the flame member 4 is provided in the path member 2 on the upstream side and the downstream side in the gas flow direction with respect to the catalyst member 3. That is, the flame generated around the catalyst member 3 is sandwiched between the two flame extinguishing members 4.

  Therefore, in the hydrogen-oxygen bonding apparatus 1 described above, the flame extinguishing member 4 can quickly extinguish the flame even when the temperature rises when hydrogen and oxygen are combined and hydrogen ignites.

  Such a hydrogen-oxygen bonding apparatus 1 is not particularly limited, but is used for bonding hydrogen and oxygen in various industrial plants that discharge hydrogen and oxygen, preferably in a nuclear power plant.

  Specifically, for example, during normal operation of a boiling water nuclear power plant, cooling water may be decomposed by radiation such as neutrons and gamma rays generated by nuclear fission of nuclear fuel material to generate hydrogen and oxygen. In addition, for example, hydrogen and oxygen may be generated due to equipment failure or the like in addition to the normal operation described above. Furthermore, radioactive waste (including contaminated water) generated in a nuclear power plant is usually sealed in a container and buried in the ground. In the container, water is decomposed by the radioactive waste to generate hydrogen and oxygen. May occur.

  Since such a mixed gas of hydrogen and oxygen is flammable, from the viewpoint of safety, the hydrogen-oxygen bonding apparatus 1 is arranged in a nuclear reactor or a radioactive waste container, and is generated as described above. Hydrogen and oxygen are recombined to produce water.

  Thus, by recombining hydrogen and oxygen, an explosion accident caused by a mixed gas (flammable gas) of these hydrogen and oxygen can be prevented.

  In particular, in the hydrogen-oxygen bonding apparatus 1, the catalyst member 3 disposed on the downstream side in the gas flow direction includes more catalysts 6 than the catalyst member 3 disposed on the upstream side in the gas flow direction. Therefore, it can suppress that reaction heat arises too much and can suppress ignition of hydrogen.

  In the above description, the plurality of catalyst members 3 are provided as the plurality of catalyst portions. However, as shown in FIG. 2, for example, a single (one) catalyst member 3 is provided, and the catalyst member 3 includes A plurality (for example, three) of catalyst regions 7 can be defined as a plurality of (for example, three) catalyst portions along the gas flow direction (see the broken line in FIG. 2). In the following, when it is necessary to distinguish the catalyst regions 7, the first catalyst region 7a, the second catalyst region 7b, and the third catalyst region are sequentially arranged from the upstream side in the gas flow direction (arrow in FIG. 2). This is referred to as 7c.

  In such a case, similarly to the above, the amount of catalyst 6 in each catalyst region 7 is designed to increase sequentially from the upstream side to the downstream side in the gas flow direction.

  Specifically, the amount of catalyst 6 in the first catalyst region 7a arranged on the most upstream side in the gas flow direction is larger than that in the other catalyst regions 7 (second catalyst region 7b and third catalyst region 7c). Designed to minimize the amount of catalyst 6.

  In addition, the second catalyst region 7b arranged second from the upstream side is designed to include more catalysts 6 than the amount of catalyst 6 in the first catalyst region 7a.

  Further, the amount of catalyst 6 in the third catalyst region 7c arranged on the most downstream side is such that the amount of catalyst 6 is the largest compared to the other catalyst regions 7 (first catalyst region 7a and second catalyst region 7b). Designed to.

  Although not shown, for example, the catalyst 6 can be designed so that the amount of the catalyst 6 gradually increases from the upstream side to the downstream side in the gas flow direction without partitioning the region.

  Even in these cases, since many catalysts 6 are provided on the upstream side in the gas flow direction rather than on the downstream side in the gas flow direction, it is possible to suppress the generation of excessive reaction heat and suppress the ignition of hydrogen. can do.

  Further, in the above description, one flame extinguishing member 4 is arranged on the upstream side and the downstream side in the gas flow direction with respect to the catalyst member 3, but for example, two or more on the upstream side and / or the downstream side in the gas flow direction ( A total of three or more flame-extinguishing members 4 can also be arranged.

  In the above description, the path member 2 is formed in a cylindrical shape, and the catalyst member 3 and the flame extinguishing member 4 having substantially the same diameter are arranged so as to share the central axis with the path 2. A hollow member extending in the flow direction (longitudinal direction) may be used, and the catalyst member 3 and the flame extinguishing member 4 are preferably the same shape as the opening shape when the hollow space of the hollow member is projected in the gas flow direction. And a porous member having a plurality of open cells 8 penetrating in the gas flow direction.

  Furthermore, in the above description, the catalyst member 3 and the flame extinguishing member 4 are arranged so as to be spaced apart from each other. For example, the catalyst member 3 and the flame extinguishing member 4 are not spaced apart from each other. They can also be placed in contact with each other. In such a case, the peripheral side walls of the catalyst member 3 and the flame extinguishing member 4 also serve as the path member 2.

DESCRIPTION OF SYMBOLS 1 Hydrogen-oxygen coupling device 2 Pass member 3 Catalyst member 4 Flame extinguishing member 5 Catalyst carrier 6 Catalyst 7 Catalyst region 8 Open cell

Claims (1)

A path member through which a gas containing hydrogen and oxygen passes;
A plurality of catalyst parts that are arranged in the path member and include a catalyst that combines hydrogen and oxygen by being in contact with the gas;
The plurality of catalyst parts are arranged along the gas flow direction,
The catalyst portion disposed on the downstream side in the gas flow direction,
Compared to the catalyst part arranged upstream in the gas flow direction,
A hydrogen-oxygen bonding apparatus comprising a large number of the catalysts.

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