JP6780847B2 - Hydrogen iodide decomposition catalyst and hydrogen production method - Google Patents

Description

The present invention relates to a hydrogen iodide decomposition catalyst that promotes a reaction in a decomposition reaction of hydrogen iodide, and a hydrogen production method using such a hydrogen iodide decomposition catalyst.

The IS (Iodine Sulfur) method is known as a method for producing hydrogen by thermally decomposing water (see Patent Document 1). The IS method is composed of the following three steps.
I Bunsen reaction step Aqueous sulfuric acid solution and hydrogen iodide aqueous solution are produced from iodine, sulfur dioxide and water.
II Hydrogen iodide concentration decomposition step After concentrating the hydrogen iodide aqueous solution obtained in the Bunsen reaction step, hydrogen iodide is decomposed to obtain hydrogen as a product and iodine to be supplied to the Bunsen reaction step.
III Sulfuric acid concentration decomposition step After concentrating the sulfuric acid aqueous solution obtained by the Bunzen reactor, the sulfuric acid is decomposed to obtain oxygen and sulfur dioxide to be supplied to the Bunzen reaction step. The sulfur dioxide obtained in this step is obtained by further decomposing sulfur trioxide produced by the decomposition of sulfuric acid.

Each of the above three steps I to III is connected to form a closed cycle.

The Bunzen reaction is an exothermic reaction, but the decomposition reaction of hydrogen iodide in the hydrogen iodide concentration decomposition step, the decomposition reaction of sulfuric acid in the sulfuric acid concentration decomposition step, and the decomposition reaction of sulfur trioxide generated by the decomposition of sulfuric acid are regarded as heat absorption reactions. To. Therefore, when the IS method is realized, heat energy is input to the hydrogen iodide concentration decomposition step and the sulfuric acid concentration decomposition step.
Japanese Unexamined Patent Publication No. 2004-107115 P. Favuzza, C. Felici, L. Nardi, P. Tarquini, A. Tito, "Kinetics of hydrogen iodide decomposition over activated carbon catalysts in pellets", Applied Catalysis B: Environmental 105 (2011) 30-40 Xiangdong Lin, Yanwei Zhang, Zhihua Wang, Rui Wang, Junhu Zhou, Kefa Cen, "Hydrogen production by HI decomposition over nickel-ceria-zirconia catalysts via the sulfur-iodine thermochemical water-splitting cycle", Energy Conversion and Management 84 (2014) ) 664-670 Laijun Wang, Songzhi Hu, Daocai Li, Qi Han, Ping Zhang, Songzhe Chen, Jingming Xu, "Effects of the second metals on the active carbon supported Pt catalysts for HI decomposition in the iodine-sulfur cycle", International J. Hydrogen Energy 39 (2014) 14161 -14165

In the IS method, both the decomposition reaction of hydrogen iodide that produces hydrogen and the decomposition reaction of sulfur trioxide that produces oxygen are restricted by the chemical equilibrium. In particular, as shown in FIG. 7, since the conversion rate of chemical equilibrium is small in the decomposition reaction of hydrogen iodide, the circulation amount of HI and I ₂ in the process is large, and the equipment for producing hydrogen becomes large.

Ce-based oxides, Ni-based catalysts and activated carbon have been mainly proposed as catalysts used for the purpose of promoting the decomposition reaction of hydrogen iodide (for example, Non-Patent Documents 1 to 3). Since the activities of Ce-based oxides and Ni-based catalysts are not necessarily high, the HI conversion rate of these catalysts is lower than the equilibrium conversion rate, which is a problem.

In addition, when only activated carbon is used as the decomposition catalyst for hydrogen iodide, the generated I ₂ is adsorbed on the catalyst, which tends to cause clogging of the catalyst bed and deactivation, so that a long-term continuous reaction is carried out. There was also the problem that it could not be done and had to be played regularly.

In order to solve the above problems, the hydrogen iodide decomposition catalyst according to the present invention is a hydrogen iodide decomposition catalyst that promotes the reaction of decomposing hydrogen iodide into iodine and hydrogen, and is a metal or a metal cation. It is composed of a porous substance carrying cerium oxide to which (hereinafter abbreviated as metal M) is added and platinum, and the metal M is a group consisting of Cu, Tb, Pr, Fe, Y, La, Ni and Mn. It is characterized by consisting of at least one metal selected from or a combination of a plurality of metals .

Further, the hydrogen iodide decomposition catalyst according to the present invention is characterized in that the porous substance is activated carbon.

Further, the hydrogen production method according to the present invention is a product obtained by decomposing a bunzen reaction step of producing a sulfuric acid aqueous solution and a hydrogen iodide aqueous solution from iodine, sulfur dioxide and water, and a hydrogen iodide aqueous solution obtained by the bunzen reaction step. A hydrogen iodide decomposition catalyst comprising a hydrogen iodide decomposition step of obtaining hydrogen as a hydrogen iodide and iodine to be supplied to the Bunzen reaction step, and a porous substance carrying cerium oxide to which metal M is added and platinum. Promotes the reaction in the hydrogen iodide decomposition step, and the metal M is of at least one metal or a plurality of metals selected from the group consisting of Cu, Tb, Pr, Fe, Y, La, Ni and Mn. It is characterized by being composed of a combination .

Further, the hydrogen production method according to the present invention is characterized in that the porous substance is activated carbon.

According to the hydrogen iodide decomposition catalyst according to the present invention, HI decomposition can be carried out at a conversion rate close to equilibrium, deactivation is difficult, and a long-term continuous reaction can be promoted.

Further, according to the hydrogen production method according to the present invention, a hydrogen iodide decomposition catalyst capable of performing HI decomposition at a conversion rate close to equilibrium, hardly deactivating, and capable of performing a long-term continuous reaction is used. Since the reaction is promoted in the hydrogen iodide decomposition step, the hydrogen production efficiency is improved.

It is a schematic block diagram which showed an example of the hydrogen production apparatus which realizes the hydrogen production method which concerns on this invention. It is a vertical sectional view of a hydrogen iodide decomposer. It is a figure which shows the temperature dependence of the equilibrium achievement rate of the comparative example which supported the hydrogen iodide decomposition catalyst which concerns on this invention, cerium oxide (CeO ₂ ) simple substance on a porous substance, and comparative example of a porous substance alone. .. Comparative example in which the hydroiodide catalyst according to the present invention and cerium oxide (CeO ₂ ) alone were supported on a porous material, a comparative example in which platinum was supported on a porous material, and a comparative example of a porous material alone. It is a figure which shows the temperature dependence of the equilibrium achievement rate of. It is a figure which shows the characteristic of the hydrogen iodide decomposition catalyst which concerns on this invention which supported Cu-added CeO ₂ on a porous substance. It is a figure which shows the time-dependent change of the hydrogen iodide decomposition catalyst 116 which concerns on this invention. It is a figure which shows the temperature dependence of the conversion rate in the decomposition reaction of hydrogen iodide.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of a hydrogen production apparatus that realizes a hydrogen production method.

The hydrogen production apparatus 1 decomposes water as a raw material by thermal decomposition to produce hydrogen (further, oxygen) as a product. The hydrogen production apparatus 1 employs the IS (Iodine Sulfur) method, and includes a Bunzen reaction apparatus 2, a hydrogen iodide concentration decomposition apparatus 3, and a sulfuric acid concentration decomposition apparatus 4.

As the heat source supplied to the hydrogen iodide concentrating and decomposing device 3 and the sulfuric acid concentrating and decomposing device 4, nuclear heat energy of a high-temperature gas furnace (not shown), solar heat, and the like are used. That is, the sensible heat of the secondary helium gas obtained via the intermediate heat exchanger 10 is used.

The intermediate heat exchanger 10 exchanges heat between the primary helium gas, which has been heated to a high temperature by the nuclear heat of the HTGR, and the secondary helium gas, which gives heat to the hydrogen production apparatus 1 side. The intermediate heat exchanger 10 is connected to a primary side pipe 10a through which the primary helium gas flows and a secondary side pipe 10b through which the secondary helium gas flows. The secondary helium gas flowing through the secondary side pipe 10b is heated to about 880 ° C. in the intermediate heat exchanger 10, and its pressure is set to about 4 MPa.

The secondary helium gas heated in the intermediate heat exchanger 10 exchanges heat with the sulfur trioxide decomposer 17, the sulfuric acid decomposer 15, and the hydrogen iodide decomposer 11, which will be described later.

The Bunsen reactor 2 includes a Bunsen reactor 5 and a two-phase separator 7.

The bunzen reactor 5 contains water (H ₂ O) as a raw material, iodine (I ₂ ) supplied from the hydrogen iodide concentrating decomposition device 3, and sulfur dioxide (SO ₂ ) supplied from the sulfuric acid concentrating decomposition device 4. ) Is supplied. In the Bunzen reactor 5, for example, under the conditions of 0.1 MPa (gauge pressure) and 100 ° C., the Bunzen reaction according to the following formula is carried out to produce an aqueous hydrogen iodide solution and an aqueous sulfuric acid solution. Since the Bunsen reaction is an exothermic reaction, no energy is input from the outside.

SO ₂ (g) + I ₂ (L) + 2H ₂ O → H ₂ SO4 (aq) + 2HI (aq) ・ ・ ・ (1)
The two-phase separator 7 separates the sulfuric acid aqueous solution and the hydrogen iodide aqueous solution obtained in the Bunsen reactor 5. The inside of the two-phase separator 7 is set to, for example, 0.1 MPa (gauge pressure) and 100 ° C. The hydrogen iodide aqueous solution and the sulfuric acid aqueous solution separated in the two-phase separator 7 are led to the hydrogen iodide concentration decomposition device 3 and the sulfuric acid concentration decomposition device 4, respectively.

The hydrogen iodide decomposing apparatus 3 includes a hydrogen iodide purification concentrator 9 and a hydrogen iodide decomposing device 11.

The hydrogen iodide purification concentrator 9 purifies the hydrogen iodide aqueous solution and concentrates the hydrogen iodide aqueous solution under the conditions of, for example, 1 MPa (gauge pressure) and 100 to 234 ° C. Hydrogen iodide is vaporized in the hydrogen iodide purification concentrator 9 and led to the hydrogen iodide decomposer 11. The thermal energy required for the purification and concentration process is input to the hydrogen iodide purification and concentration device 9.

The hydrogen iodide decomposer 11 decomposes hydrogen iodide according to the following formula under the conditions of, for example, 1 MPa (gauge pressure) and 450 ° C.

2 HI (g) → H ₂ (g) + I ₂ (g) ・ ・ ・ (2)
The hydrogen iodide decomposition reaction is an endothermic reaction, and therefore thermal energy is input. That is, the hydrogen iodide decomposition reaction of the formula (2) proceeds by heat exchange with the gas pipe 13 through which the heated secondary helium gas flows in the intermediate heat exchanger 10.

The hydrogen decomposed in the hydrogen iodide decomposer 11 is taken out as a product. Further, the iodine decomposed in the hydrogen iodide decomposer 11 is guided to the Bunsen reactor 5. The unreacted hydrogen iodide is returned to the hydrogen iodide purification concentrator 9. A more detailed configuration of the hydrogen iodide decomposer 11 will be described later.

The sulfuric acid concentrating and decomposing device 4 includes a sulfuric acid refining concentrator 14, a sulfuric acid decomposing device 15, and a sulfur trioxide decomposing device 17.

The sulfuric acid purification concentrator 14 purifies sulfuric acid and concentrates an aqueous sulfuric acid solution under the conditions of, for example, 0.1 MPa (gauge pressure) and 100 to 391 ° C. The thermal energy required for the purification and concentration process is input to the sulfuric acid purification and concentrator 14. The water separated from the sulfuric acid aqueous solution in the sulfuric acid purification concentrator 14 is sent to the Bunsen reactor 5. Sulfuric acid (liquid) purified and concentrated in the sulfuric acid purification concentrator 14 is led to the sulfuric acid decomposer 15.

The sulfate decomposer 15 decomposes sulfuric acid according to the following formula under the conditions of, for example, 2 MPa (gauge pressure) and 391 to 527 ° C.

H ₂ SO ₄ (L) → H ₂₀ (g) + SO ₃ (g) ・ ・ ・ (3)
The sulfuric acid decomposition reaction is an endothermic reaction, and therefore thermal energy is input. That is, the sulfate decomposition reaction of the formula (3) proceeds by heat exchange with the gas pipe 19 through which the heated secondary helium gas flows in the intermediate heat exchanger 10.

The sulfur trioxide and water vapor decomposed in the sulfuric acid decomposer 15 are guided to the sulfur trioxide decomposer 17.

The sulfur trioxide decomposer 17 decomposes sulfur trioxide according to the following formula under the conditions of, for example, 2 MPa (gauge pressure), 527 to 850 ° C.

SO ₃ (g) → SO ₂ (g) + 1 / 2O ₂ (g) ・ ・ ・ (4)
The sulfur trioxide decomposition reaction is an endothermic reaction, and therefore thermal energy is input. That is, the sulfur trioxide decomposition reaction of the formula (4) proceeds by heat exchange with the gas pipe 20 through which the heated secondary helium gas flows in the intermediate heat exchanger 10. As shown in FIG. 1, in order to bring the highest temperature to the sulfur trioxide decomposer 17, the secondary helium gas heated in the intermediate heat exchanger 10 is first introduced to the sulfur trioxide decomposer 17. It is supposed to be taken. The secondary helium gas that has completed heat exchange in the sulfur trioxide decomposer 17 undergoes heat exchange in the sulfuric acid decomposer 15 and the hydrogen iodide decomposer 11.

The oxygen generated in the sulfur trioxide decomposer 17 is taken out of the system as a product. Further, the sulfur dioxide produced in the sulfur trioxide decomposer 17 is guided to the Bunzen reactor 5 together with a small amount of water vapor.

As described above, according to the hydrogen production apparatus 1 according to the present embodiment, by charging water as a raw material into the Bunzen reactor 2, hydrogen as a product is concentrated and decomposed by sulfuric acid from the hydrogen iodide concentrated decomposition apparatus 3. It can be obtained from device 4.

Next, a more detailed configuration of the hydrogen iodide decomposer using the hydrogen iodide decomposition catalyst 116 according to the present invention will be described. The outline of the hydrogen iodide decomposer 11 is shown in FIG.

The hydrogen iodide decomposer 11 is a reaction vessel composed of an upper mirror 101, a body 102, a bottom plate 103, and a heat transfer tube 120. A hydrogen iodide decomposition catalyst 116 that promotes the decomposition of hydrogen iodide gas is loaded in the heat transfer tube 120. Since the decomposition reaction of hydrogen iodide gas is an endothermic reaction, it is circulated to the outside of the heat transfer tube 120 so that it can be heated by using a heating gas so that the temperature of the hydrogen iodide gas does not decrease. The heat transfer tube 120 is attached to an upper tube plate 110 provided at the upper part of the body 102 and a lower tube plate 111 provided at the lower part. A baffle plate 125 for increasing the flow velocity of the heating gas is installed on the body 102.

The hydrogen iodide gas is introduced from the hydrogen iodide gas inlet nozzle 108 provided in the lower part of the cylinder 102, rises inside the heat transfer tube 120, and is the next step from the mixed gas outlet nozzle 105 provided in the upper part of the cylinder 102. Will be sent to.

The heating gas enters from the heating gas inlet nozzle 109 provided in the upper part of the body 102, and while descending the outside of the heat transfer tube 120, heats the hydrogen iodide gas or the mixed gas inside the heat transfer tube 120. , Return to the system from the heating gas outlet nozzle 104 provided at the lower part of the body 102.

The hydrogen iodide gas entering from the hydrogen iodide gas inlet nozzle 108 decomposes into a mixed gas while rising inside the heat transfer tube 120 filled with the hydrogen iodide decomposition catalyst 116. As the mixed gas, hydrogen gas and undecomposed hydrogen iodide gas are taken out from the mixed gas outlet nozzle 105 of the upper mirror 101 above the heat transfer tube 120.

Next, the hydrogen iodide decomposition catalyst 116 according to the present invention used in the hydrogen iodide decomposition device 11 as described above will be described.

The hydrogen iodide decomposition catalyst according to the present invention used in the hydrogen iodide decomposer 11 is a hydrogen iodide decomposition catalyst that promotes a reaction (reaction of equation (2)) for decomposing hydrogen iodide into iodine and hydrogen. It is composed of a simple substance of cerium oxide (CeO ₂ ) or a porous substance carrying cerium oxide (CeO ₂ ) to which a metal or metal cation (hereinafter abbreviated as metal M) is added and platinum (Pt). It is a feature. Here, activated carbon, zeolite, alumina (Al ₂ O ₃ ), silica (SiO ₂ ), and the like can be used as the porous substance.

Further, as the metal M used for the hydroiodide catalyst, at least one metal selected from the group consisting of Cu, Zr, Tb, Pr, Fe, Y, La, Ni and Mn can be used. Further, as the metal M, a combination of a plurality of metals selected from the group consisting of Cu, Zr, Tb, Pr, Fe, Y, La, Ni, and Mn may be used.

Hereinafter, Ce _1-x M _x O _{2 in} which metal M is added to cerium oxide (CeO ₂ ) may be simply referred to as CeMO ₂ . The ratio (x) of adding the metal M is preferably 0.1 ≦ x ≦ 0.3 based on the amount of the metal M dissolved in cerium oxide (CeO ₂ ).

Here, for the metal M added to cerium oxide (CeO ₂ ), an element that expresses electron conduction that contributes to the introduction and movement of oxygen defects related to activity improvement was selected. Specifically, the metal M selected from this viewpoint is Cu, Zr, Tb, Pr, Fe, Y, La, Ni, Mn.

The method of adding metal M to cerium oxide (CeO ₂ ) will be described. In this embodiment, activated carbon was used as the porous substance. The activated charcoal used in this embodiment is M563 (manufactured by Osaka Gas Chemical Co., Ltd., Shirasagi activated charcoal, surface area of about 1500 m ² / g) or MSC30 (manufactured by Kansai Thermochemical Co., Ltd., specific surface area: 3300 m ² / g). It is either.

The procedure for producing the hydroiodide catalyst according to the present invention is shown below.
(1) After suspending the activated charcoal in ion-exchanged water, it is once boiled and cooled.
(2) Prepare an aqueous solution in which cerium nitrate (Ce (NO ₃ ) ₃ ) and element M (nitrate) are mixed at a predetermined mixing ratio. The mixing ratio is adjusted so that the ratio of the elements is 9: 1, for example, when it is desired to prepare an oxide of Ce _0.9 M _0.1 O ₂ .
(3) The activated carbon of (1) is mixed with the aqueous solution of (2) and evaporated to dryness. Here, the amount of the aqueous solution of (2) is adjusted so that the weight ratio with the activated carbon is 10 to 30 wt% (the amount of CeMO ₂ supported). (The weight ratio with activated carbon is the weight ratio of ceria dioxide containing element M)
(4) The solid obtained in (3) is dried overnight at 80 ° C. in a vacuum dryer, calcined at 400 ° C. for 2 hours in N2, and then suspended in ion-exchanged water again.
(5) Platinum chloride acid (H ₂ PtCl ₆ , H ₂ PtCl ₄ ) is dissolved in water, added so that Pt is 1 wt% with respect to activated charcoal, and evaporated to dryness.
(6) After drying overnight at 80 ° C. in a vacuum dryer, hydrogen reduction (100 ml / min) is performed at 500 ° C. for 1 hour to obtain a hydrogen iodide decomposition catalyst according to the present invention.

Next, the temperature dependence of the equilibrium achievement rate of the hydrogen iodide decomposition catalyst according to the present invention, a comparative example in which cerium oxide (CeO ₂ ) alone is supported on a porous material, and a comparative example of the porous material alone is shown. This will be described with reference to 3.

MSC30 and M562 are activated charcoals with different surface areas, 3300 m ² / g and 1500 m ² / g, respectively. It is considered that the higher the surface area of activated carbon is used as the carrier, the higher the dispersion of supported CeO ₂ and Pt and the higher the exposed surface area, so that higher hydrogen iodide decomposition activity can be obtained.

Next, a comparative example in which the hydroiodide catalyst according to the present invention and a simple substance of cerium oxide (CeO ₂ ) are supported on a porous substance, a comparative example in which platinum is supported on a porous substance, and a simple substance of the porous substance. The temperature dependence of the equilibrium achievement rate of the comparative example of the above will be described with reference to FIG.

FIG. 4 shows the results when Cu, Zr, Tb, Pr, Fe, Y, La, Ni, Mn, are used as the metal M.

FIG. 4 shows the activity of hydrogen iodide decomposition at SV = 1000h ^-1 . The equilibrium achievement rate was used as an index showing the activity. The equilibrium achievement rate indicates the ratio of the hydrogen iodide conversion rate of the catalyst used to the equilibrium conversion rate.

For comparison, FIG. 4 also shows the results of the activated charcoal alone and the results of the activated charcoal carrying platinum. It can be seen that the hydrogen iodide decomposition catalyst according to the present invention exhibits higher activity than activated carbon in all temperature ranges. Further, in the hydroiodide catalyst according to the present invention, regarding the metal M added to cerium oxide (CeO ₂ ), all of Cu, Zr, Tb, Pr, Fe, Y, La, Ni and Mn have good results. It can be seen that

Further, in the hydrogen iodide decomposition catalyst according to the present invention, the equilibrium achievement rate exceeded 100%, but this was due to the shift of equilibrium due to the adsorption of I ₂ on the catalyst at the initial stage of the reaction, and the adsorption occurred. When equilibrium is reached, the equilibrium conversion rate is almost within the experimental error. That is, hydrogen iodide can be decomposed to almost equilibrium-controlled conditions.

FIG. 5 shows the temperature dependence of the activity of Pt-CeCuO ₂ / MSC30 and Pt-CeCuO ₂ / M56 carrying Cu-added CeO ₂ which was relatively active in M563 activated carbon. In the legend of FIG. 5, for example, "1% Pt-30% CeCuO ₂ / MSC-30" has a Pt loading amount of 1 wt% and a Ce _0.9 Cu _0.1 O ₂ loading amount of 30 wt%. It is shown that. It can be seen that the hydrogen iodide decomposition catalyst according to the present invention can almost achieve an equilibrium conversion rate at all temperatures from 300 ° C to 500 ° C. Therefore, it can be seen that the catalyst carrying Cu-added CeO2 exhibits excellent activity.

FIG. 6 shows the time course of the hydrogen iodide decomposition catalyst according to the present invention. The results in FIG. 6 are based on Pt-CeCuO ₂ / MSC30, Pt-CeCuO ₂ / M563.

As shown in FIG. 6, it can be seen that the activity with a high equilibrium conversion rate is maintained for 100 to 200 hours. As described above, the hydrogen iodide decomposition catalyst according to the present invention has long-term stability without causing deactivation, which has been a conventional problem.

As described above, according to the hydrogen iodide decomposition catalyst according to the present invention, HI decomposition can be performed at a conversion rate close to equilibrium, deactivation is difficult, and a long-term continuous reaction can be promoted. ..

Further, according to the hydrogen production method according to the present invention, HI decomposition can be performed at a conversion rate close to equilibrium, and a hydrogen iodide decomposition catalyst capable of performing a long-term continuous reaction with less deactivation is used. Since the reaction is promoted in the hydrogen iodide decomposition step, the efficiency of hydrogen production is improved.

Further, they have found that the hydrogen iodide decomposition catalyst according to the present invention can achieve the equilibrium activity of the hydrogen iodide decomposition reaction from a low temperature range of 300 ° C., can maintain the activity even at a high space velocity, and can maintain stable performance for a long period of time. It was.

Therefore, by introducing the hydrogen iodide decomposition catalyst according to the present invention, the hydrogen iodide decomposition reaction at an equilibrium conversion rate becomes possible even at a relatively low temperature of 300 ° C., and the process equipment by improving the thermal efficiency and reducing the amount of catalyst. It is possible to reduce the size of the catalyst and the frequency of catalyst replacement.

1 ... Hydrogen production device 2 ... Bunzen reactor 3 ... Hydrogen iodide concentration decomposition device 4 ... Sulfuric acid concentration decomposition device 5 ... Bunzen reactor 6 ... Moisture film separation device 7 ... Two-phase separator 9 ... Hydrogen iodide purification concentrator 10 ... Intermediate heat exchanger 10a ... Primary side piping 10b ... Secondary side piping 11 ... Hydrogen iodide cracker 14 ... Sulfuric acid purification concentrator 15 ... Sulfuric acid decomposer 17 ... Sulfuric acid cracker 19 ... Gas pipe 20 ... Gas pipe 101 ... Top mirror 102 ... Body 103 ... Bottom plate 104 ... Heating gas outlet nozzle 105 ... Mixed gas outlet nozzle 108 ... Hydrogen iodide gas inlet nozzle 109 ... Heating gas inlet nozzle 110 ... Upper tube plate 111 ... Lower tube plate 116・ ・ ・ Hydrogen iodide decomposition catalyst 120 ・ ・ ・ Heat transfer tube 125 ・ ・ ・ Interfering plate

Claims (4)

A hydrogen iodide decomposition catalyst that promotes the reaction of decomposing hydrogen iodide into iodine and hydrogen.
It is composed of a porous substance carrying platinum and cerium oxide to which a metal or metal cation (hereinafter abbreviated as metal M) is added .
A hydrogen iodide decomposition catalyst , wherein the metal M comprises at least one metal selected from the group consisting of Cu, Tb, Pr, Fe, Y, La, Ni, and Mn, or a combination of a plurality of metals . The hydrogen iodide decomposition catalyst according to claim 1 , wherein the porous substance is activated carbon. A Bunsen reaction step to produce an aqueous sulfuric acid solution and an aqueous hydrogen iodide solution from iodine, sulfur dioxide and water,
The hydrogen iodide decomposition step of decomposing the hydrogen iodide aqueous solution obtained by the Bunzen reaction step to obtain hydrogen as a product and iodine to be supplied to the Bunzen reaction step is included.
The reaction in the hydrogen iodide decomposition step is promoted by a hydrogen iodide decomposition catalyst composed of cerium oxide to which metal M is added and a porous substance supporting platinum .
A method for producing hydrogen , wherein the metal M comprises at least one metal selected from the group consisting of Cu, Tb, Pr, Fe, Y, La, Ni, and Mn, or a combination of a plurality of metals . The hydrogen production method according to claim 3 , wherein the porous substance is activated carbon.