JP5165865B2 - Hydrogen iodide production method and hydrogen iodide production apparatus - Google Patents

Description

  The present invention relates to a hydrogen iodide production method and a hydrogen iodide production apparatus that can be used in a hydrogen production method using a thermochemical decomposition method (IS method).

  There is a thermochemical decomposition process as a method for extracting hydrogen from water. Water is chemically converted to a chemical form containing hydrogen, and hydrogen is extracted using thermal energy. Depending on the type of chemical used, there are many different approaches.

  One of the thermochemical decomposition processes is the IS method (see Patent Documents 1 to 7 and Non-Patent Documents 1 and 2). The IS method is based on the following three basic reactions.

I ₂ + SO ₂ + 2H ₂ O → 2HI + H ₂ SO ₄ (1)
_{2HI → H 2 + I 2 (} 2)
2H ₂ SO ₄ → 2SO ₂ + 2H ₂ O + O ₂ (3)
First, water is reacted with iodine (I ₂ ) and sulfur dioxide (SO ₂ ) to produce hydrogen iodide (HI) and sulfuric acid (H ₂ SO ₄ ). This reaction is also called the Bunsen reaction. The produced hydrogen iodide is thermally decomposed at 400 ° C. or higher and decomposed into hydrogen (H ₂ ) and iodine. Hydrogen, which is the thermal decomposition product of hydrogen iodide, is the final goal produced by the thermochemical decomposition process. The iodine produced at this time is returned to the Bunsen reaction and reused. The sulfuric acid produced by the Bunsen reaction is also thermally decomposed at a high temperature of 600 ° C. or higher, and the generated sulfur dioxide is also returned to the Bunsen reaction and reused.

  The IS method is a method of thermally decomposing water into hydrogen and oxygen using iodine and sulfur dioxide.

  Since the IS method is a method in which water is chemically changed to hydrogen iodide and thermally decomposed to extract hydrogen, generation and concentration of hydrogen iodide and removal of impurities in the Bunsen reaction are important.

  The concentration of the aqueous hydrogen iodide solution is about 57% by weight under atmospheric pressure, and even when distilled, it distills as an azeotrope with water and does not exceed 57%. An aqueous hydrogen iodide solution having a concentration of 70% that exceeds 57% of the azeotropic composition with a commercially available reagent releases excess hydrogen iodide in the aqueous solution after opening, and the concentration decreases to 57%.

  The aqueous hydrogen iodide solution obtained by the IS method Bunsen reaction is obtained by adding excess iodine to a mixed solution of sulfuric acid and hydrogen iodide and separating into two phases from the difference in specific gravity. Since hydrogen iodide has a high affinity with iodine, it forms a complex with iodine and moves to the lower phase liquid. The complex formation reaction between major iodide ions and iodine is shown below.

I ₂ + I ⁻ → I ₃ − (4)
2I ₂ + I ⁻ → I ₅ − (5)
^{_{3I 2 + I - → I 7}} - (6)
^{_{4I 2 + I - → I 9}} - (7)
Iodide ions are thought to stably concentrate in the lower phase by complexing with iodine. However, the concentration of hydrogen iodide in the lower phase liquid extracted by the Bunsen reaction carried out under atmospheric pressure conditions does not exceed 57%, and it is difficult to isolate hydrogen iodide by distilling the lower phase liquid. It is.

  In addition, sulfuric acid and hydrogen iodide, which are slightly dissolved in the lower phase liquid, react with each other, and sulfur compounds such as sulfur and hydrogen sulfide are generated as by-products, and hydrogen iodide in the lower phase is reduced.

As a reason why the concentration of hydrogen iodide in the lower phase liquid does not exceed the azeotropic composition, it is considered that the solubility of sulfur dioxide in water under atmospheric pressure conditions is not so large as about 5% by weight. When dissolved in water, sulfur dioxide hydrates and changes to sulfurous acid (H ₂ SO ₃ ) as shown in the following reaction formula. A chemical species in which one molecule of water is hydrated per one molecule of sulfur dioxide is generally known sulfurous acid.

SO ₂ + H ₂ O → H ₂ SO ₃ (8-1)
SO ₂ + nH ₂ O → SO ₂ .nH ₂ O (8-2)
Sulfurous acid is reducible and causes an oxidation-reduction reaction with iodine to produce hydrogen iodide and sulfuric acid.

_{H 2 SO 3 + I 2 +} H 2 O → 2HI + H 2 SO 4 (9)
Therefore, the IS method Bunsen reaction involves reaction formula (8-1) in which sulfur dioxide dissolves in water to produce sulfurous acid and reaction formula (9) in which sulfurous acid and iodine react to produce hydrogen iodide and sulfuric acid. It is formed from two elementary reactions.

Under atmospheric pressure conditions, the chemical reaction equilibrium constant of the formula (8-1) is not large, and less sulfurous acid is produced. As the chemical reaction formula (9) proceeds, a side reaction in which a sulfur compound is generated also occurs. Therefore, it is difficult for the hydrogen iodide concentration in the lower phase liquid to exceed the azeotropic composition.
Japanese Patent Publication No. 60-52081 Japanese Examined Patent Publication No. 60-48442 Japanese Examined Patent Publication No. 4-37001 Japanese Examined Patent Publication No. 4-37002 Japanese Patent No. 40899939 Japanese Patent No. 4089940 Japanese Patent No. 4127644 M. Sakurai, H. Nakajima, R. Amir, K. Onuki, and S. Shimizu, Experimental study on side-reaction occurrence condition in the iodine-sulfur thermochemical hydrogen production process, International Journal of Hydrogen Energy, 25 (2000) 613-619. M. Sakurai, H. Nakajima, K. Onuki, and S. Shimizu, Investigation of 2 liquid phase separation characteristic on the iodine-sulfur thermochemical hydrogen production process, International Journal of Hydrogen Energy, 25 (2000) 605-611.

  In the prior art, the Bunsen reaction is performed under atmospheric pressure conditions, and then two-phase separation is performed to separate the produced hydrogen iodide and sulfuric acid by the difference in specific gravity. At this stage, the concentration percentage by weight of hydrogen iodide (= (Mass of hydrogen iodide contained in lower phase liquid) / (sum of mass of hydrogen iodide and water contained in lower phase liquid)) cannot exceed the azeotropic composition and is contained in the lower phase liquid The hydrogen iodide concentration was 57% or less.

  By the way, as a cause of making it difficult to isolate hydrogen iodide from the lower phase liquid, there is sulfuric acid dissolved in the lower phase liquid. When the lower phase liquid is distilled, it reacts with hydrogen iodide due to the presence of sulfuric acid and produces sulfur and hydrogen sulfide.

_{14HI + 2H 2 SO 4 → H} 2 S + 7I 2 + S + 8H 2 O (11)
Since 7 mol of hydrogen iodide is consumed per 1 mol of sulfuric acid, if there is a slight amount of sulfuric acid, hydrogen iodide concentrated in the lower phase disappears. A similar reaction occurs with sulfur dioxide. 5 mol of hydrogen iodide is consumed per 1 mol of sulfur dioxide.

_{10HI + 2SO 2 → H 2 S} + 5I 2 + S + 4H 2 O (12)
Therefore, it is necessary to remove the sulfur compound from the lower phase liquid before isolating hydrogen iodide by distillation.

  An object of the present invention is to make it possible to efficiently isolate hydrogen iodide from a lower phase solution containing hydrogen iodide obtained by the Bunsen reaction.

In order to achieve the above object, the method for producing hydrogen iodide according to the present invention generates hydrogen iodide and sulfuric acid by reacting sulfur dioxide, iodine and water under a pressure condition of 0.1 MPa or more in gauge pressure. A reaction step of adding a separation solution having a specific gravity intermediate between hydrogen iodide and sulfuric acid and chemically stable to hydrogen iodide and sulfuric acid, and hydrogen iodide becomes a lower phase liquid, A separation step of separating three phases so that sulfuric acid becomes an upper phase liquid and the separated liquid becomes an intermediate phase liquid formed between the lower phase liquid and the upper phase liquid; and a sulfur compound is removed from the upper phase liquid. And a removing step for removing.

The hydrogen iodide production apparatus according to the present invention is a hydrogen iodide production apparatus for producing hydrogen iodide by reacting sulfur dioxide, iodine and water, and has an intermediate specific gravity between hydrogen iodide and sulfuric acid. And containing a chemically stable separation solution against hydrogen iodide and sulfuric acid, and reacting sulfur dioxide, iodine and water under pressure conditions of 0.1 MPa or more in gauge pressure to produce hydrogen iodide. And a reaction vessel for producing sulfuric acid, and a distillation column for distilling a lower phase solution produced in the reaction vessel and obtained by three- phase separation.

  According to the present invention, hydrogen iodide can be efficiently isolated from the lower phase solution containing hydrogen iodide obtained by the Bunsen reaction.

  Embodiments of a hydrogen iodide production method and a hydrogen iodide production apparatus according to the present invention will be described below.

[First Embodiment]
FIG. 1 is a flowchart showing a method for producing hydrogen iodide according to the first embodiment of the present invention.

That is, sulfur dioxide (SO ₂ ) is supplied and sulfur dioxide is dissolved in water under pressurized conditions. Then, an aqueous solution of iodine and sulfur dioxide is reacted under a pressurized condition (Bunsen reaction). Thereby, hydrogen iodide and sulfuric acid are produced. Furthermore, iodine and water are added to the product solution under pressure conditions to separate the two phases, and further, an aqueous sulfur dioxide solution is added to cause the Bunsen reaction, while hydrogen iodide is taken into the lower phase and hydrogen iodide is shared. Concentrate above boiling composition.

  At this time, a liquid (separated liquid) having a specific gravity between an upper phase composed of an aqueous sulfuric acid solution and a lower phase composed of iodine and hydrogen iodide is added to the Bunsen reactor. This separated liquid does not mix with the upper phase liquid and the lower phase liquid, and forms an intermediate phase during phase separation. After the concentration step, the aqueous sulfuric acid solution in the upper phase liquid is transferred to the sulfuric acid decomposition step, and the lower phase hydrogen iodide is transferred to the hydrogen iodide distillation step.

  As the pressurizing condition, for example, the gauge pressure is preferably 0.1 MPa or more.

  The specific gravity of the separated liquid needs to be intermediate between the upper phase liquid and the lower phase liquid, and is preferably about 1.5 to 2.3, for example.

  As the separation liquid, a liquid that hardly chemically reacts with the upper phase liquid and the lower phase liquid and is hardly soluble in water is preferable. For example, an ionic liquid is preferable. An ionic liquid is a “salt” composed of only ions (anions and cations), and in particular, a liquid compound is called an ionic liquid. Sometimes called “room temperature molten salt”, “room temperature molten salt”, or the like.

  Examples of ionic liquids that can be used here include (a) 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, (b) 1-propyl-3-methylimidazolium iodide, (c) 1-ethyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) imide (1 -ethyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) imide), (d) N, N, N ′, N′-tetramethyl-N ″ -ethylguanidinium tris (pentafluoroethyl) trifluorophosphate (N, N, N, N ′, N′-tetramethyl-N ″ -ethylguanidinium tris (pentafluoroethyl) trifluorophosphate). The chemical structures of these ionic fluids are shown in FIGS. 2 (a) to 2 (d), respectively.

  In the above steps, before reacting iodine, sulfur dioxide and water to produce hydrogen iodide and sulfuric acid, sulfur dioxide is first dissolved in water under pressure and hydrated. Since hydrated sulfur dioxide has reducibility, when it is added to iodine, it causes an oxidation-reduction reaction with iodine to produce hydrogen iodide and sulfuric acid. In the stage where the amount of iodine is excessive with respect to the amount of hydrogen iodide produced by the Bunsen reaction, phase separation occurs simultaneously with the Bunsen reaction. Since iodine and hydrogen iodide have a high affinity, a complex-forming reaction between iodide ions and iodine (formulas (4) to (7)) proceeds to produce polyiodide, which is concentrated to the lower phase.

  The sulfuric acid aqueous solution having a small specific gravity is phase-separated into the upper phase. At this time, by adding an intermediate phase of the separated liquid having an intermediate specific gravity between the upper phase and the lower phase, the sulfuric acid aqueous solution slightly remaining in the lower phase undergoes phase separation due to the specific gravity difference, and at the same time, Since neither the upper phase nor the lower phase is mixed, the aqueous sulfuric acid solution does not diffuse from the intermediate phase to the lower phase until chemical equilibrium, and the aqueous sulfuric acid solution is not brought into the lower phase. Therefore, hydrogen iodide and sulfuric acid produced by the Bunsen reaction are completely phase-separated by adding an intermediate phase.

  According to the present embodiment, by adding an intermediate phase that is not mutually soluble with the upper phase and the lower phase, it is possible to prevent the sulfuric acid aqueous solution from remaining in and contacting with the lower phase. Thereby, the side reaction (Formula (11)) with the hydrogen iodide and sulfuric acid which were produced | generated by the Bunsen reaction can be suppressed. As a result, during the Bunsen reaction and phase separation, it is possible to prevent the generation of sulfur and interference with hydrogen iodide concentration due to side reactions, and a lower phase liquid containing a high concentration of hydrogen iodide can be obtained.

  Furthermore, according to this embodiment, the Bunsen reaction is performed under a pressurized condition of a gauge pressure of 0.1 MPa or more. This pressurization provides the effects described below.

  FIG. 3 shows a graph in which the conversion rate of sulfur dioxide, which has reacted with iodine to produce hydrogen iodide and sulfuric acid when sulfur dioxide is passed through an aqueous iodine solution, is plotted against the gauge pressure. The conversion rate of sulfur dioxide is one half of the amount of hydrogen iodide produced according to reaction formula (1) or the amount of sulfur dioxide added with the amount of sulfuric acid added. Shows the percentage.

  The solubility of sulfur dioxide at atmospheric pressure is about 5 to 10% by weight percentage concentration, and the conversion rate was about 8% at a gauge pressure of 0 MPa (atmospheric pressure). This is almost equal to the solubility of sulfur dioxide at atmospheric pressure. Consistent. Up to 0.2 MPa, the conversion rate of sulfur dioxide increases almost in proportion to the pressure, and at 0.2 MPa or more, all of the added sulfur dioxide reacts, and the conversion rate reaches 100%. It can be seen that by applying pressure, the conversion is markedly improved.

  On the other hand, FIG. 4 shows the pressure dependence of the hydrogen iodide concentration in the lower phase liquid produced by the Bunsen reaction. In this figure, the horizontal axis is the pressure, and the vertical axis is the weight percentage concentration of hydrogen iodide in the lower phase liquid ([HI] = (mass of hydrogen iodide contained in the lower phase liquid) / (included in the lower phase liquid). The sum of the masses of hydrogen iodide and water)).

  In FIG. 4, the hydrogen iodide concentration in the lower phase liquid is 34% under an atmospheric pressure condition of 0 MPa as a gauge pressure, and does not exceed 57% of the azeotropic composition, but a pressure condition of 0.1 MPa or more. It was found that the hydrogen iodide concentration in the lower phase liquid produced below exceeded 57% of the azeotropic composition. When the hydrogen iodide concentration of the lower phase liquid exceeds the azeotropic composition, it becomes easy to isolate hydrogen iodide from the lower phase liquid in the subsequent distillation step, and the lower phase liquid is subjected to iodine by pressurization. It can be seen that the concentration of hydrogen fluoride can be improved.

  By applying pressure, sulfur dioxide dissolves in water and becomes hydrated, and instantaneously undergoes a redox reaction with dissolved iodine to produce hydrogen iodide and sulfuric acid. Under atmospheric pressure conditions, the rate of oxidation-reduction reaction between hydrated sulfur dioxide and iodine was in the vicinity of 8%, but 100% can be reacted by applying pressure and adding sulfur dioxide to the aqueous iodine solution.

[Second Embodiment]
FIG. 5 is a schematic configuration diagram of a hydrogen iodide production apparatus according to the second embodiment of the present invention.

  The sulfur dioxide dissolving part is for dissolving sulfur dioxide in water, and receives pressurized sulfur dioxide supplied from a sulfur dioxide feeder (for example, sulfur dioxide cylinder) 9 into the dissolving tank 2. Yes. A heater 20 is attached to the sulfur dioxide supplier 9. Water is stored in the water supply tank 4, and a carrier gas supply device 11 such as a nitrogen gas cylinder is connected to pressurize the inside of the water supply tank 4. The water in the water supply tank 4 is pressurized by the pressure of the carrier gas (for example, nitrogen gas) supplied from the carrier gas supply device 11, and the pressurized water is supplied to the dissolution tank 2 through a pipe.

  A pressure gauge 8 a and a mass flow meter 12 are connected to the piping from the sulfur dioxide supplier 9 to the dissolution tank 2, and the pressure and mass flow rate of sulfur dioxide supplied to the dissolution tank 2 can be measured. A back pressure valve 21 and a pressure gauge 8b are connected to the upper part of the dissolution tank 2 so that the pressure in the dissolution tank 2 can be adjusted.

  The bottom of the dissolution tank 2 is connected to the reaction tank 1. A pressure gauge 8 c and a back pressure valve 10 a are connected to the upper part of the reaction tank 1, and the lower part is connected to the reboiler 3. A distillation column 7 is disposed above the reboiler 3. The upper part of the distillation column 7 is connected to the scrubber 13 through the condenser 6, the hydrogen iodide recovery pipe 5, and the back pressure valve 10b in this order.

  In the sulfur dioxide dissolving part, water is put in the dissolving tank 2 in advance from the water supply tank 4, and sulfur dioxide is injected into the dissolving tank 2 while being heated to 30 to 50 ° C. by the heater 20. At this time, sulfur dioxide is supplied by adjusting and controlling the pressure in the dissolution tank 2 using the back pressure valve 21 or a pressurizing pump (not shown) so that the pressure in the dissolution tank 2 becomes 0.1 MPa or more by the pressure gauge 8b.

  After the sulfur dioxide is completely dissolved and hydrated in the dissolution tank 2 to form an aqueous sulfite solution, the hydrated sulfur dioxide is supplied to the reaction tank 1. In the reaction tank 1, iodine, water, and an intermediate phase forming liquid (separated liquid) are put in advance. In the reaction tank 1, iodine and sulfur dioxide hydrated water (sulfurous acid aqueous solution) are subjected to a Bunsen reaction to generate hydrogen iodide and sulfuric acid. After the reaction, only the lower phase liquid containing hydrogen iodide is pumped to the distillation column 7 via the reboiler 3 and subjected to pressure distillation. The distilled hydrogen iodide is cooled with a refrigerant and collected in a hydrogen iodide recovery pipe 5 as a liquefied gas.

  According to this embodiment, before reacting iodine, sulfur dioxide and water to produce hydrogen iodide and sulfuric acid, sulfur dioxide is first dissolved in water under pressure and hydrated. By injecting sulfur dioxide into water in the dissolution tank 2 under pressurized conditions, sulfur dioxide can be completely dissolved in water, and an aqueous sulfite solution is generated. Since hydrated sulfur dioxide has reducibility, when it is added to iodine, it causes an oxidation-reduction reaction with iodine to produce hydrogen iodide and sulfuric acid. By pumping to the reaction vessel 1 while maintaining the pressurized state, the sulfurous acid aqueous solution maintaining a high concentration can be oxidized and reduced with iodine. Therefore, the hydrogen iodide produced per unit amount of sulfur dioxide to be used in comparison with atmospheric pressure conditions is larger under pressurized conditions.

  In the stage where the amount of iodine is excessive with respect to the amount of hydrogen iodide produced by the Bunsen reaction, phase separation occurs simultaneously with the Bunsen reaction. Since iodine and hydrogen iodide have a high affinity, a complex-forming reaction between iodide ions and iodine (formulas (4) to (7)) proceeds to produce polyiodide, which is concentrated to the lower phase.

  The sulfuric acid aqueous solution having a small specific gravity is phase-separated into the upper phase. At this time, by adding a liquid phase (separated liquid) having an intermediate specific gravity between the upper phase and the lower phase, the sulfuric acid aqueous solution slightly remaining in the lower phase undergoes phase separation due to the difference in specific gravity, while Since neither the upper phase nor the lower phase is mixed, the aqueous sulfuric acid solution does not diffuse from the intermediate phase to the lower phase until chemical equilibrium, and the aqueous sulfuric acid solution is not brought into the lower phase. Therefore, hydrogen iodide and sulfuric acid produced by the Bunsen reaction are completely phase-separated by adding an intermediate phase.

  Here, the separation liquid is, for example, an ionic liquid, as in the first embodiment. In normal two-phase separation without using a separate solution, polyiodide produced by the complexing reaction between iodine and hydrogen iodide is concentrated to the lower phase solution, but the upper phase sulfuric acid aqueous solution is always in contact with the lower phase. For this reason, the sulfuric acid aqueous solution in the upper phase shifts to the lower phase from the interface between the upper phase and the lower phase until the mutual equilibrium is reached. In addition, generation of sulfur due to side reactions is also observed at the interface.

  The ionic liquid does not dissolve in most solvents including water and is chemically stable, and therefore does not react and decompose. In the phase separation of hydrogen iodide and sulfuric acid produced by the Bunsen reaction, the presence of an intermediate phase allows three or more phases to be separated, and hydrogen iodide and sulfuric acid can be completely separated. When the Bunsen reaction occurs in the lower phase, hydrogen iodide stays in the lower phase as it is because of its affinity with iodine, but sulfuric acid moves to the upper phase via the intermediate phase because of its low specific gravity. Since the intermediate phase is an ionic liquid in which neither the upper phase nor the lower phase is mutually soluble, the sulfuric acid transferred to the upper phase is not mixed into the aqueous solution of polyiodide in the lowermost phase.

  According to this embodiment, by installing the sulfur dioxide dissolution tank 2 in the previous stage of the reaction tank 1 as an apparatus, the sulfur dioxide can be pressurized and completely dissolved in the solvent water. Generation of sulfur by the reaction can be avoided. Also, all the injected sulfur dioxide can be reacted with iodine. As a result, there is a risk that non-hydrated sulfur dioxide will not be brought into the reaction vessel 1, and sulfur dioxide and hydrogen iodide produced by the Bunsen reaction may cause side reactions to produce sulfur compounds such as sulfur and hydrogen sulfide. Can be avoided (formula (12)).

  In addition, in the phase separation of hydrogen iodide and sulfuric acid produced by the Bunsen reaction, by adding an intermediate phase of ionic liquid, sulfuric acid can be completely separated into the upper phase and hydrogen iodide can be separated into the lower phase. Since sulfuric acid does not dissolve into the lower phase, it is possible to avoid side reactions between hydrogen iodide and sulfuric acid in the lower phase. Similarly, since the upper phase of the sulfuric acid aqueous solution and the lower phase of polyhydrogen iodide are not in contact with each other through the intermediate phase, hydrogen iodide and sulfuric acid do not cause a side reaction at the interface (formula (12)). By adding an intermediate phase, the lower phase is composed only of iodine, hydrogen iodide and water. Since the ratio of hydrogen iodide and water exceeds 57% which is an azeotropic composition under pressurized conditions, hydrogen iodide can be easily isolated from the lower phase liquid by distillation. Since the lower phase liquid distilled at this time does not contain sulfur compounds such as sulfuric acid, hydrogen iodide can be isolated without causing a side reaction between hydrogen iodide and sulfuric acid during the lower phase liquid distillation. .

It is a flowchart which shows the hydrogen iodide manufacturing method which concerns on the 1st Embodiment of this invention. It is a figure which shows the example chemical structure of the ionic liquid applicable as a separation liquid in embodiment of this invention, Comprising: (a) is 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, (b ) Is 1-propyl-3-methylimidazolium-iodide, (c) is 1-ethyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) imide, (d) is N, N, The figure which shows N ', N'-tetramethyl-N' '-ethylguanidinium tris (pentafluoroethyl) trifluorophosphate. It is a graph which shows the effect of embodiment of this invention, Comprising: The conversion rate of the sulfur dioxide which reacted with iodine and produced | generated hydrogen iodide and the sulfuric acid when aeration was carried out to iodine aqueous solution was plotted with respect to a gauge pressure. Chart. It is a graph which shows the effect of embodiment of this invention, Comprising: The graph which shows the pressure dependence of the hydrogen iodide density | concentration in the lower phase liquid produced | generated by the Bunsen reaction. The horizontal axis is the pressure, and the vertical axis is the concentration percentage of hydrogen iodide in the lower phase liquid ([HI] = (mass of hydrogen iodide contained in the lower phase liquid) / (hydrogen iodide contained in the lower phase liquid and The sum of the mass of water)). It is a schematic block diagram of the hydrogen iodide manufacturing apparatus which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reaction tank 2 ... Dissolution tank 3 ... Reboiler 4 ... Water supply tank 5 ... Hydrogen iodide recovery pipe 6 ... Condenser 7 ... Distillation towers 8, 8a, 8b, 8c ... Pressure gauge 9 ... Sulfur dioxide supplier 10a, 10b ... Back pressure valve 11 ... Nitrogen gas cylinder (carrier gas supply device)
12 ... Mass flow meter 13 ... Scrubber 20 ... Heater 21 ... Back pressure valve

Claims (8)

A reaction step of producing hydrogen iodide and sulfuric acid by reacting sulfur dioxide, iodine and water under a pressure condition of 0.1 MPa or more at a gauge pressure ;
Adding a separation liquid having a specific gravity intermediate between hydrogen iodide and sulfuric acid and chemically stable to hydrogen iodide and sulfuric acid;
Separation step of separating three phases so that hydrogen iodide becomes a lower phase liquid, sulfuric acid becomes an upper phase liquid, and the separated liquid becomes an intermediate phase liquid formed between the lower phase liquid and the upper phase liquid When,
A removal step of removing sulfur compounds from the upper phase liquid;
A method for producing hydrogen iodide, comprising: The method for producing hydrogen iodide according to claim 1, wherein the reaction step includes a step of generating an aqueous solution containing iodine and a step of injecting sulfur dioxide into the aqueous solution containing iodine. The reaction step includes a dissolution step of dissolving sulfur dioxide in water to produce a sulfur dioxide aqueous solution or a sulfurous acid aqueous solution, and a mixing step of mixing the sulfur dioxide aqueous solution or the sulfurous acid aqueous solution with an aqueous solution containing iodine. The method for producing hydrogen iodide according to claim 1 or 2, characterized in that: The method for producing hydrogen iodide according to any one of claims 1 to 3, wherein the separation liquid is an ionic liquid . The method for producing hydrogen iodide according to any one of claims 1 to 4, wherein the removing step includes a step of isolating hydrogen iodide by distilling the lower phase liquid . In a hydrogen iodide production apparatus for producing hydrogen iodide by reacting sulfur dioxide, iodine and water,
  A separation liquid having a specific gravity intermediate between hydrogen iodide and sulfuric acid and chemically stable against hydrogen iodide and sulfuric acid is contained, and sulfur dioxide and A reaction vessel for reacting iodine with water to produce hydrogen iodide and sulfuric acid;
  A distillation column for distilling a lower phase liquid produced in the reaction vessel and obtained by three-phase separation;
  An apparatus for producing hydrogen iodide, comprising: It further has a dissolution tank for dissolving sulfur dioxide in water under a pressure condition of 0.1 MPa or more at a gauge pressure to generate a sulfur dioxide aqueous solution or a sulfurous acid aqueous solution,
It is configured to transfer the sulfur dioxide aqueous solution or the sulfurous acid aqueous solution generated in the dissolution tank to the reaction tank under a pressurized condition,
An apparatus for producing hydrogen iodide according to claim 6 . The hydrogen iodide production apparatus according to claim 6 or 7, wherein the separation liquid is an ionic liquid .

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