JP5224471B2 - Method and apparatus for producing nitric oxide gas - Google Patents

Description

  The present invention relates to a method and apparatus for producing nitric oxide (NO) gas that occupies an important position as an industrial gas, a medical gas, or the like used as a raw material for semiconductor devices, for example.

As a method for producing nitric oxide gas, a method of reducing nitric acid (HNO ₃ ) with sulfur dioxide (SO ₂ ) is known as represented by the following reaction formula (1) (see Patent Document 1).
2HNO ₃ + 3SO ₂ + 2H ₂ O → 2NO + 3H ₂ SO ₄ (1)

Further, as represented by the following reaction formula (2), ferrous sulfate (FeSO ₄ ) is reacted with sodium nitrite (NaNO ₂ ) under acidic conditions with sulfuric acid (H ₂ SO ₄ ) or the like. Thus, a method for obtaining nitric oxide gas is also known (see Non-Patent Document 1).
2NaNO ₂ + 2FeSO ₄ + 2H ₂ SO ₄ → 2NO + Fe ₂ (SO ₄ ) ₃ + Na ₂ SO ₄ (2)

JP-A-9-175804

Inorg. Syn., 2,126 (1946)

In the method represented by the reaction formula (1), only 1 mol of nitric oxide can be obtained from 1.5 mol of sulfur dioxide. In other words, it shows that only 30 g of nitric oxide having a molecular weight of 30 can be obtained from 96 g of sulfur dioxide having a molecular weight of 64. In addition, nitric acid (HNO ₃ ), which is a reaction substrate in reaction formula (1), is a compound having a higher degree of oxidation than nitrous acid (HNO ₂ ), and in order to increase the degree of oxidation in an industrial production process, nitric acid is used. The process is added rather than the case of manufacturing. That is, there is a problem that the method represented by the reaction formula (1) is not economically excellent.

In the method represented by the reaction formula (2), when 1 mol (30 g) of nitric oxide is obtained, 0.5 mol of ferric sulfate (200 g as a pentahydrate) is formed, and the ferric sulfate is disposed of as waste. As a result, there is a problem that the cost for processing is increased.
An object of this invention is to provide the manufacturing method and manufacturing apparatus of nitric oxide gas which can solve the subject of the above prior arts.

  In the method for producing nitric oxide gas according to the present invention, a nitric oxide compound is reacted with an acid to produce nitric oxide gas via nitrous acid, and is produced at the time of producing nitric oxide gas via the nitrous acid. Nitric oxide gas is generated by reacting nitric acid or nitrogen dioxide with at least one of sulfur dioxide and sulfite compounds.

There are two embodiments of the method for producing nitric oxide gas according to the present invention.
In the first aspect of the method of the present invention, a first stage process for producing a reaction by-product containing nitric acid and nitric oxide gas by reacting a nitrite compound with an acid, and the reaction by-product It is preferable to provide a second stage step of generating nitric oxide gas by reacting nitric acid contained in the catalyst with at least one of sulfur dioxide and sulfite compound.
In this case, in the first step, by reacting an acid with the nitrous acid compound, for example, a continuous reaction represented by the following reaction formula (3) and reaction formula (4) occurs. Reaction formula (3) illustrates the case where sodium nitrite is used as the nitrite compound and sulfuric acid is used as the acid.
3NaNO ₂ + 1.5H ₂ SO ₄ → 3HNO ₂ + 1.5Na ₂ SO ₄ (3)
3HNO ₂ → 2NO + HNO ₃ + H ₂ O (4)
The self-reduction reaction of nitrous acid represented by the reaction formula (4) proceeds under acidic conditions, and preferably proceeds at a pH value of 5 or less.
When the reaction formula (3) and the reaction formula (4) are added together, the first stage process is represented by the following reaction formula (5). By this reaction, a reaction by-product containing nitric acid and nitric oxide gas are formed. can get.
3NaNO ₂ + 1.5H ₂ SO ₄ → 2NO + HNO ₃ + H ₂ O + 1.5Na ₂ SO ₄ (5)

In the second step, nitric acid contained in the reaction by-product is reacted with at least one of sulfur dioxide and sulfite compound, for example, as shown in the following reaction formula (6). Nitric oxide gas is obtained. Reaction formula (6) illustrates the case where nitric acid is reacted with sulfur dioxide, and the reaction in this case is equal to the reaction represented by reaction formula (1). Nitric oxide gas is obtained by the reduction reaction of nitric acid.
HNO ₃ + 1.5SO ₂ + H ₂ O → NO + 1.5H ₂ SO ₄ (6)
When the reaction formula (5) in the first stage process and the reaction formula (6) in the second stage process are added together, the whole reaction is expressed by the following reaction formula (7).
3NaNO ₂ + 1.5SO ₂ → 3NO + 1.5Na ₂ SO ₄ (7)
As apparent from the reaction formula (7), 3 moles of nitric oxide can be obtained from 1.5 moles of sulfur dioxide, and per mole compared with the reaction represented by the conventional reaction formula (1). Nitric oxide gas obtained from sulfur dioxide is tripled. That is, since the amount of nitric oxide gas generated per certain amount of sulfur dioxide increases, the amount of waste per certain amount of nitric oxide gas obtained can be relatively reduced. Moreover, since the amount of nitric oxide gas generated can be increased by using nitrous acid having a low oxidation number instead of nitric acid having a high oxidation number as in the prior art, it is economically superior.

The acid that acts on the nitrite compound in the first step is not limited to sulfuric acid, but nitrite is produced by reaction with the nitrite compound, and the resulting nitrous acid is oxidized by an auto-redox reaction under acidic conditions. Any acid that can generate nitrogen gas may be used. For example, hydrochloric acid or nitric acid may be used. Further, the nitrite compound used in the first step is not limited to sodium nitrite, and for example, potassium nitrite can be used.
In the second step, the sulfite compound used in place of or together with sulfur dioxide is not particularly limited, and for example, sodium bisulfite (NaHSO ₃ ) and / or sodium sulfite (Na ₂ SO ₃ ) is used. be able to.

  When the reaction in the first stage process and the reaction in the second stage process are caused to occur in separate reactors, the apparatus for carrying out the method for producing nitric oxide gas of the present invention comprises a nitrite compound and an acid. A first reactor to be introduced; a second reactor into which at least one of sulfur dioxide and a sulfite compound is introduced; and nitric oxide gas produced by reacting a nitrite compound with an acid. In order to send a first outflow passage for flowing out from one reactor and a reaction by-product containing nitric acid generated by reacting a nitrite compound with an acid from the first reactor to the second reactor. And a nitric oxide gas generated by reacting nitric acid contained in the reaction by-product with at least one of sulfur dioxide and a sulfurous acid compound, for causing the nitric oxide gas to flow out of the second reactor. 2 Preferably provided with Detchi Prefecture.

In the second aspect of the method of the present invention, nitric oxide gas is produced together with a reaction byproduct containing nitrogen dioxide by reacting the nitrite compound with an acid in the presence of at least one of sulfur dioxide and sulfite compound. It is preferable to generate nitrogen monoxide gas by reacting at least one of sulfur dioxide and sulfurous acid compound with nitrogen dioxide contained in the reaction by-product.
In this case, for example, a series of elementary reactions occurs under acidic conditions represented by the following reaction formulas (8) to (11). Here, a case where sodium nitrite and sulfuric acid are reacted in the presence of sulfur dioxide is illustrated.
2NaNO ₂ + H ₂ SO ₄ → 2HNO ₂ + Na ₂ SO ₄ (8)
2HNO ₂ → NO + NO ₂ + H ₂ O (9)
NO ₂ + SO ₂ → NO + SO ₃ (10)
SO ₃ + H ₂ O → H ₂ SO ₄ (11)
The following reaction formula (12) is a total reaction formula obtained by adding the elementary reaction formulas of the reaction formulas (8) to (11).
2NaNO ₂ + SO ₂ → 2NO + Na ₂ SO ₄ (12)
This reaction formula is the same as the above reaction formula (7). Therefore, the amount of waste per a certain amount of nitric oxide gas obtained in the same manner as in the first aspect can be relatively reduced, and it is economically excellent. Furthermore, nitric oxide can be obtained with high purity under mild conditions without passing through nitric acid during the reaction.
In this case as well, the acid that acts on the nitrous acid compound is not limited to sulfuric acid, and nitrous acid is produced by reaction with the nitrous acid compound, and nitric oxide gas is produced by the auto-redox reaction of the produced nitrous acid under acidic conditions. Any acid can be used as long as it can generate, for example, hydrochloric acid or nitric acid. Moreover, a nitrite compound is not limited to sodium nitrite, For example, potassium nitrite can be used. The sulfite compound used in place of or together with sulfur dioxide is not particularly limited, and for example, sodium bisulfite (NaHSO ₃ ) and / or sodium sulfite (Na ₂ SO ₃ ) can be used.
In this case, an apparatus for carrying out the method for producing nitric oxide gas of the present invention includes a reactor into which a nitrite compound, an acid, and at least one of sulfur dioxide and sulfite compound are introduced, and nitrous acid. Nitric oxide gas produced by reacting a compound with an acid, and nitrogen dioxide contained in a reaction byproduct produced by reacting a nitrite compound with an acid, at least one of sulfur dioxide and sulfite compounds It is preferable to provide an outflow passage for allowing the nitric oxide gas produced by the reaction with the outflow channel to flow out from the reactor.

  In the method of the present invention, it is preferable to provide a gas scrubber that generates nitrogen monoxide gas by reducing nitrogen dioxide gas contained in the nitrogen monoxide gas with an aqueous solution of a sulfurous acid compound. Thereby, the purity of the generated nitric oxide gas can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, nitric oxide gas can be manufactured economically, and the industrially excellent method and apparatus which can reduce a waste can be provided.

Structure explanatory drawing of the manufacturing apparatus of nitric oxide gas concerning a 1st embodiment of the present invention. Structure explanatory drawing of the manufacturing apparatus of the nitric oxide gas which concerns on 2nd Embodiment of this invention. Structure explanatory drawing of the manufacturing apparatus of nitric oxide gas concerning a 3rd embodiment of the present invention. Structure explanatory drawing of the manufacturing apparatus of nitric oxide gas concerning a 4th embodiment of the present invention.

The present invention will be specifically described below by showing embodiments, but the first aspect according to the present invention is the first to third embodiments, and the second aspect according to the present invention. Is the fourth embodiment.
The nitric oxide gas production apparatus 1 according to the first embodiment shown in FIG. 1 includes a first reactor 2 and a second reactor 3. Both reactors 2, 3 are each constituted by a packed tower. The packing packed in each packed tower is not particularly limited, and for example, Raschig ring can be used. Each of the reactors 2 and 3 is provided with heating devices 4 and 5 for controlling the reaction temperature. Each of the heating devices 4 and 5 includes, for example, a heater capable of controlling the heating temperature, and is built in a jacket that covers the outer periphery of the reactors 2 and 3. The 1st storage part 6 integrated in the lower part of the 1st reactor 2 and the 2nd storage part 7 integrated in the lower part of the 2nd reactor 3 are provided. Reaction by-products falling from the first reactor 2 are stored in the first storage unit 6, and reaction by-products falling from the second reactor 3 are stored in the second storage unit 7. The storage units 6 and 7 are provided with heating devices 12a and 12b for controlling the temperature of the reaction by-products, thereby preventing a decrease in the reaction temperature in the second stage process.

  An introduction path 8 for continuously introducing a nitrite compound into the first reactor 2 is provided. One end of the introduction path 8 is connected to a supply source 9 of the nitrite compound, and the other end is disposed above the first reactor 2. In this embodiment, an aqueous sodium nitrite solution is supplied as the nitrite compound. Thereby, the sodium nitrite aqueous solution is introduced into the first reactor 2 from above through the introduction path 8 at a flow rate set via a flow rate controller (not shown) such as a flow rate control valve.

  An introduction path 10 for continuously introducing the acid into the first reactor 2 is provided. One end of the introduction path 10 is connected to the acid supply source 11, and the other end is disposed above the first reactor 2. In this embodiment, a sulfuric acid aqueous solution is supplied as the acid. An aqueous sulfuric acid solution is introduced into the first reactor 2 from above through an introduction path 10 at a flow rate set via a flow rate controller (not shown) such as a flow rate control valve.

  In the packed tower constituting the first reactor 2, the reaction by-product containing nitric acid and monoxide are caused by the reaction caused by the action of the acid introduced from the introduction passage 10 on the nitrite compound introduced from the introduction passage 8. Nitrogen gas is generated. This is the reaction in the first stage process, and is represented by the above reaction formula (5) in this embodiment. In order to cause the nitrogen monoxide gas generated by this reaction to flow out from the first reactor 2, a first outflow passage 13 that is continuous with the upper end opening of the first reactor 2 is provided.

  The concentration of the acid aqueous solution introduced from the introduction path 10 is not particularly limited. However, if the concentration is too low, the volumetric efficiency is lowered because the necessary amount for the reaction is increased, and the produced nitric oxide is used as a gas. The ratio of dissolving in the reaction solution without flowing out increases. For example, when an aqueous sulfuric acid solution is used, the concentration is preferably 5% by weight to 100% by weight, and more preferably 50% by weight to 100% by weight.

  When the reaction temperature in the first stage process is lowered, the reaction rate is lowered, and the ratio of the produced nitric oxide to be dissolved in the reaction solution without flowing out as a gas is increased. On the other hand, when the reaction temperature is increased, nitrogen dioxide gas is generated from the by-produced nitric acid and mixed into the nitrogen monoxide gas. Therefore, the reaction temperature in the first step is preferably 0 ° C. to 100 ° C., more preferably 10 ° C. to 80 ° C. In addition, you may produce | generate nitrogen monoxide gas by reduce | restoring the nitrogen dioxide gas mixed in nitrogen monoxide gas with the aqueous solution of a sulfurous acid compound. Therefore, for example, a gas scrubber 40 that performs gas scrubbing with an aqueous solution of a sulfurous acid compound is preferably disposed in the first outflow passage 13 as indicated by a chain line in the figure. Thereby, even if nitrogen dioxide gas mixes in nitrogen monoxide gas, the mixed nitrogen dioxide gas can be reduced to generate nitrogen monoxide gas, and the purity of the nitrogen monoxide gas can be improved. The aqueous solution of the sulfite compound used for the gas cleaning may be used for the reduction reaction of nitric acid in the second step.

  The reaction by-product in the first stage process is stored in the first storage unit 6 by dropping downward from the lower end opening of the first reactor 2. The reaction by-products of this embodiment are nitric acid, sodium sulfate, and water. A communication path 20 a that connects the inside of the first reservoir 6 and the upper side of the second reactor 3 is provided. The reaction by-product stored in the 1st storage part 6 is continuously introduce | transduced by the flow volume set to the 2nd reactor 3 with the pump 20b arrange | positioned at the communication path 20a. That is, the communication path 20a and the pump 20b constitute a feeding device 20 for sending reaction by-products from the first reactor 2 to the second reactor 3 as a reaction liquid.

  An introduction path 30 for continuously introducing sulfur dioxide into the second reactor 3 is provided. One end of the introduction path 30 is connected to a supply source 31 of sulfur dioxide (sulfurous acid gas), and the other end is disposed below the second reactor 3. Sulfur dioxide is introduced into the second reactor 3 through the introduction path 30 at a flow rate set via a flow rate controller (not shown) such as a flow rate control valve.

  In the packed tower constituting the second reactor 3, nitric oxide gas is generated by reacting nitric acid contained in the reaction by-product introduced from the communication path 20 a with sulfur dioxide introduced from the introduction path 30. Is done. This is the reaction in the second stage process, and is represented by the above reaction formula (6) in this embodiment. In order to cause the generated nitric oxide gas to flow out from the second reactor 3, a second outflow path 32 connected to the upper end opening of the second reactor 3 is provided. The reaction by-product in the second stage process is stored in the second storage unit 7 by dropping downward from the lower end opening of the second reactor 3. The reaction by-product in the second stage process of the present embodiment is sulfuric acid, and is stored in the second storage unit 7 together with sodium sulfate and water of the reaction by-product in the first stage process that has not been subjected to the reaction. .

  In the reaction system of the first embodiment shown in FIG. 1, the reaction rate decreases as the reaction temperature in the second stage process decreases. On the other hand, when the reaction temperature rises, the amount of water vapor mixed into the generated nitric oxide gas increases, and a large amount of energy is required for its removal. Therefore, the reaction temperature in the second step is preferably 30 ° C to 120 ° C, more preferably 40 ° C to 110 ° C.

  The introduction flow rate of the nitrous acid compound from the introduction path 8, the introduction flow rate of the acid from the introduction path 10, the feed flow rate of the reaction by-product through the communication path 20a, and the introduction flow rate of sulfur dioxide from the introduction path 30 are as follows: What is necessary is just to determine experimentally according to the desired production | generation speed | rate of gas.

  FIG. 2 shows a nitric oxide gas production apparatus 101 according to the second embodiment of the present invention. Hereinafter, differences from the first embodiment will be described, and the same parts are denoted by the same reference numerals, and description thereof will be omitted. First, the 1st reactor 102 and the 2nd reactor 103 are each comprised by the reaction tank, and the storage part only for storage of the reaction by-product is not provided. The agitation blades 102a and 103a disposed inside the reactors 102 and 103 are driven by the motors 102b and 103b, whereby the reaction liquid is agitated. Nitrogen monoxide produced from the first outflow passage 13 by the reaction in the first stage process caused by introducing the nitrous acid compound into the first reactor 102 from the introduction passage 8 and introducing the acid from the introduction passage 10. Gas is spilled. The reaction by-product generated in the first reactor 102 is sent as a reaction solution to the second reactor 103 by the feeding device 20. Nitrogen monoxide gas generated from the second outflow path 32 flows out by the reaction in the second stage process caused by introducing sulfur dioxide into the second reactor 103 from the introduction path 30, and enters the second reactor 103. The reaction by-product in the second stage process is stored together with the reaction by-product in the first stage process that has not been subjected to the reaction. Others are the same as in the first embodiment.

  FIG. 3 shows a nitric oxide gas production apparatus 201 according to the third embodiment of the present invention. Hereinafter, differences from the first embodiment will be described, and the same parts are denoted by the same reference numerals, and description thereof will be omitted. First, the 1st reactor 202a and the 2nd reactor 202b which comprise the manufacturing apparatus 201 are integrated. That is, the 2nd reactor 202b comprised by the reaction tank is integrated in the lower part of the 1st reactor 202a comprised by the packed tower. A first heating device 204 for controlling the reaction temperature in the first reactor 202a and a second heating device 205 for controlling the reaction temperature in the second reactor 202b are provided. No feeding device is provided. The other ends of the introduction path 8 for continuously introducing the nitrous acid compound and the introduction path 10 for continuously introducing the acid are arranged above the first reactor 202a. The other end of the introduction path 30 for continuously introducing sulfur dioxide is disposed inside the second reactor 202b. In the first reactor 202a, a reaction by-product containing nitric acid and nitric oxide gas are generated by a reaction caused by the action of the acid introduced from the introduction passage 10 on the nitrite compound introduced from the introduction passage 8. Is done. The produced reaction by-product falls from the first reactor 202a and is stored as a reaction liquid in the second reactor 202b. In the second reactor 202b, nitric oxide gas is generated by reacting nitric acid contained in the reaction byproduct with sulfur dioxide introduced from the introduction path 30. In order to flow out the nitrogen monoxide gas generated by both reactions, an outflow path 206 is provided which is continuous with the upper end opening of the first reactor 202a. In the second reactor 202b, the reaction by-product in the first stage process and the reaction by-product in the second stage process that have not been subjected to the reaction are stored as a reaction liquid. An outlet 202c for taking out the reaction liquid stored in the second reactor 202b is provided. Others are the same as in the first embodiment.

FIG. 4 shows a nitric oxide gas production apparatus 301 according to the fourth embodiment of the present invention, which is a method for producing nitric oxide gas according to the second aspect. Hereinafter, differences from the first embodiment will be described, and the same parts are denoted by the same reference numerals, and description thereof will be omitted. First, the production apparatus 301 is provided with a single reactor 302 constituted by a reaction tank, not two separate and independent reactors, and a single heating device 304 for controlling the reaction temperature is also provided. A storage part and a feeding device dedicated to storing objects are not provided. The reaction liquid is stirred by driving the stirring blade 302a disposed inside the reactor 302 by the motor 302b. The reactor 302 has an introduction path 8 for continuously introducing a nitrite compound, an introduction path 30 for continuously introducing sulfur dioxide, and an introduction path 30 ′ for continuously introducing a sulfite compound. The other end of each introduction path 8, 30, 30 ′ is disposed inside the reactor 302. One end of the introduction path 30 'is connected to a sulfite compound supply source 31'. In this embodiment, a sodium hydrogen sulfite aqueous solution is supplied as a sulfite compound. The reactor 302 is charged with a predetermined amount of acid, and in this embodiment, an aqueous sulfuric acid solution is charged.
Into the reactor 302 charged with acid, an aqueous sodium nitrite solution is introduced via the introduction path 8, sulfur dioxide is introduced via the introduction path 30, and an aqueous sodium hydrogen sulfite solution is introduced via the introduction path 30 ′ via the introduction path 11. Thus, a sulfuric acid aqueous solution can be introduced. That is, the reaction liquid is kept acidic in the reactor 302, and the nitrous acid compound is charged into the reactor 302 while keeping the reaction liquid always containing at least one of sulfur dioxide and sulfite compound. As a result, the nitric oxide gas is produced together with the reaction by-product containing nitrogen dioxide by the reaction of the nitrous acid compound with the acid in the presence of at least one of sulfur dioxide and sulfurous acid compound, and the reaction by-product is produced. Nitric oxide gas is produced by the reaction of nitrogen dioxide contained in the product with the sulfite compound.
The reaction of the present embodiment is different from the reaction in the first to third embodiments, and nitric oxide gas can be generated even at a low temperature. For example, when sodium nitrite and sulfuric acid are reacted in the presence of sulfur dioxide, the elementary reaction of this embodiment is expressed by the above reaction formulas (8) to (11). Moreover, when sodium nitrite and sulfuric acid are reacted in the presence of sodium hydrogen sulfite, the reaction temperature is preferably 0 ° C. to 100 ° C., more preferably 0 ° C. to 80 ° C. When the reaction temperature is lower than 0 ° C., the reaction rate is slow, and when the reaction temperature is high, the amount of water accompanying nitrogen monoxide may increase. The reason why the reaction temperature can be lowered as compared with the first aspect of the present invention is that the reaction intermediate does not pass through nitric acid as shown in the reaction formulas (8) to (11).
An outflow path 306 provided in the upper part of the reactor 302 is provided in order to flow out the nitric oxide gas generated by the reaction from the reactor 302. A gas scrubber 40 that generates nitrogen monoxide gas by reducing nitrogen dioxide gas that has not been reduced to nitrogen monoxide gas in the reactor 302 with an aqueous solution of a sulfurous acid compound may be provided in the outflow path 306. Reaction by-products that have not been subjected to the reaction are stored in the reactor 302. An outlet 302 c for taking out the reaction liquid stored in the reactor 302 is provided. Others are the same as in the first embodiment.

The following experiment was conducted using the manufacturing apparatus 1 of the first embodiment.
The first reactor 2 and the second reactor 3 were each composed of a packed column in which a glass column having an inner diameter of 6 cm and a height of 30 cm was packed with a magnetic Raschig ring having a diameter of 6 mm, a length of 6 mm, and a thickness of 0.4 mm. The first reservoir 6 and the second reservoir 7 are each made of glass and have a volume of 2 liters.
A sodium nitrite aqueous solution having a concentration of 50% by weight was introduced into the first reactor 2 through the introduction path 8 at a flow rate of 1000 g / hour (7.25 mol / hour). Further, an aqueous sulfuric acid solution having a concentration of 70% by weight was dropped into the first reactor 2 through the introduction path 10 at a flow rate of 1000 g / hour (7.14 mol / hour). The first reactor 2 was heated from the outside at 40 ° C. by the heating device 4. As a result, a reaction by-product and nitric oxide gas were generated by a reaction caused by the action of sulfuric acid on sodium nitrite. The generated nitric oxide gas was discharged from the first outflow passage 13 and recovered. The reaction by-product containing nitric acid was kept at about 40 ° C. by the heating device 12 in the first reservoir 6.
The reaction by-product stored in the first storage unit 6 was introduced into the second reactor 3 as a reaction liquid. The introduction flow rate of the reaction by-product into the second reactor 3 by the feeding device 20 was set to about 2000 g / hour so that the reaction by-product stored in the first storage unit 6 was held at about 1 liter. . Further, sulfur dioxide (sulfurous acid gas) was introduced into the second reactor 3 through the introduction path 30 at a flow rate of 224 g / hour (3.50 mol / hour). The second reactor 3 was heated from the outside at 80 ° C. by the heating device 5. Thereby, in the packed tower which comprises the 2nd reactor 3, the nitric oxide gas was produced | generated by making the nitric acid contained in the reaction by-product flowing down react with the rising sulfur dioxide. The generated nitric oxide gas was discharged from the second outflow passage 32 and collected.
The amount of nitric oxide gas generated during the 1 hour from the lapse of 5 hours after the start of continuous operation of the production apparatus 1 is 105.3 liters from the first reactor 2 in terms of anhydrous, standard condition, From the second reactor 3, the total amount was 58.5 liters, 158.5 liters (212 g, 7.08 mol), and the yield was 97.7% based on sodium nitrite.

The following experiment was performed using the manufacturing apparatus 201 of the third embodiment.
The first reactor 202a is constituted by a packed column in which a glass column having an inner diameter of 6 cm and a height of 30 cm is packed with a magnetic Raschig ring having a diameter of 6 mm, a length of 6 mm, and a thickness of 0.4 mm, and the second reactor 202b has a capacity. A 2-liter glass reactor was used.
An aqueous sodium nitrite solution having a concentration of 50% by weight was dropped into the first reactor 202a through the introduction path 8 at a flow rate of 1000 g / hour (7.25 mol / hour). Further, an aqueous sulfuric acid solution having a concentration of 70% by weight was dropped into the first reactor 202a through the introduction path 10 at a flow rate of 1000 g / hour (7.14 mol / hour). Further, sulfur dioxide (sulfurous acid gas) was introduced into the second reactor 202b through the introduction path 30 at a flow rate of 224 g / hour (3.50 mol / hour). The first reactor 202a was externally heated at 80 ° C. by the first heating device 204, and the second reactor 202b was externally heated at 80 ° C. by the first heating device 205. As a result, a reaction by-product and nitric oxide gas are generated by a reaction generated by allowing sulfuric acid to act on sodium nitrite in the first reactor 202a, and are included in the reaction by-product in the second reactor 202b. Nitric oxide gas was produced by reacting nitric acid with sulfur dioxide. The generated nitric oxide gas was recovered from the outflow path 206. The reaction liquid stored in the second reactor 202b was taken out from the take-out port 202c during operation so as not to exceed about 1 liter.
The amount of nitric oxide gas generated during the first hour after the start of continuous operation of the production apparatus 201 is 147.8 liters (198 g, 6.60 mol) in terms of anhydrous and standard conditions. The yield was 91.0% based on sodium nitrite.

The following experiment was performed using the manufacturing apparatus 301 of the fourth embodiment.
The reactor 302 was constituted by a glass reaction tank having a capacity of 2 liters.
The reactor 302 was previously charged with 1000 g of a 50% by weight sulfuric acid aqueous solution, and the liquid temperature was 30 ° C.
Next, an aqueous sodium sulfite solution having a concentration of 30% by weight is introduced through the introduction passage 8 at a flow rate of 1000 g / hour (7.25 mol / hour), and an aqueous sodium hydrogen sulfite solution having a concentration of 30% by weight is introduced through the introduction passage 30 '. At a flow rate of 1320 g / hour (3.80 mol / hour), an aqueous sulfuric acid solution having a concentration of 50% by weight was further introduced into the reactor 302 through the introduction path 11 at a flow rate of 1400 g / hour. A reaction occurred simultaneously with the introduction, and nitrogen monoxide gas was generated. The generated nitric oxide gas was discharged from the outflow passage 306 and recovered. In the reactor 302, the reaction solution was stirred by the stirring blade 302a. Further, the reaction liquid stored in the reactor 302 was taken out from the outlet 302c during operation so as not to exceed about 1 liter.
The amount of nitric oxide gas produced during the 1 hour from the time point 5 hours after the start of the reaction in the reactor 302 was 153.3 liters (205 g, 6.84 mol) in terms of anhydrous and standard conditions. The yield was 94.4% based on sodium nitrite.

  According to each of the above examples, it can be confirmed that nitric oxide gas can be generated with high yield.

The present invention is not limited to the above embodiments and examples.
For example, although sodium nitrite is used as the nitrite compound in the above embodiment, a nitrite compound that can generate a reaction by-product containing at least one of nitric acid and nitrogen dioxide and nitric oxide gas by reaction with an acid. If it is, it will not specifically limit, For example, it may replace with sodium nitrite or may use potassium nitrite with sodium nitrite.

  In the above embodiment, sulfuric acid is used as the acid. However, the acid is not particularly limited as long as it is an acid that can generate nitric oxide gas via nitrous acid by reaction with a nitrous acid compound. For example, hydrochloric acid or nitric acid may be used.

  In the first to third embodiments, the nitrous acid compound and the acid are simultaneously introduced into the reactor to cause the reaction, but after introducing the nitrous acid compound into the reactor, the acid may be introduced to cause the reaction. Further, a solid phase nitrous acid compound may be introduced into a reactor storing liquid phase acid, or a liquid phase acid may be introduced into a reactor containing solid phase nitrite compound, From the viewpoint of controlling the reaction, it is preferable to use an aqueous solution of a nitrite compound.

  In the first to third embodiments, nitric acid was reduced by sulfur dioxide in the first step, but nitric acid was reduced by using sulfite instead of sulfur dioxide or by using both sulfur dioxide and sulfite compound. Therefore, the second reactor 3, 103, 202b of the first to third embodiments may be provided with a sulfite compound introduction path 30 'as indicated by a chain line.

  In the above embodiment, sodium bisulfite is used as the sulfite compound, but it is not particularly limited as long as nitric acid can be reduced. For example, sodium sulfite may be used in place of or together with sodium bisulfite.

  DESCRIPTION OF SYMBOLS 1, 101, 201, 301 ... Nitric oxide gas production apparatus, 2, 102 ... First reactor, 3, 103 ... Second reactor, 13 ... First outflow path, 20 ... Feeding device, 32 ... Second Outflow channel, 206, 306 ... Outflow channel

Claims (6)

Nitric oxide gas is produced via nitrous acid by reacting nitrous acid compound with acid,
Nitric oxide gas production method for producing nitric oxide gas by reacting nitric acid or nitrogen dioxide produced during production of nitric oxide gas via nitrous acid with at least one of sulfur dioxide and sulfurous acid compound . A first stage process for generating a reaction by-product containing nitric acid and nitric oxide gas by reacting a nitrous acid compound with an acid;
2. The nitric oxide gas according to claim 1, further comprising a second step of generating nitric oxide gas by reacting nitric acid contained in the reaction by-product with at least one of sulfur dioxide and a sulfurous acid compound. Manufacturing method. Nitric oxide gas is produced together with a reaction byproduct containing nitrogen dioxide by reacting a nitrite compound with an acid in the presence of at least one of sulfur dioxide and sulfurous acid compound, and is contained in the reaction byproduct. The method for producing nitric oxide gas according to claim 1, wherein nitrogen monoxide gas is produced by reacting nitrogen dioxide with at least one of sulfur dioxide and a sulfurous acid compound. An apparatus for producing nitric oxide gas for carrying out the method according to claim 2,
A first reactor into which a nitrous acid compound and an acid are introduced;
A second reactor into which at least one of sulfur dioxide and sulfite compound is introduced;
A first outflow passage for letting out nitric oxide gas generated by reacting a nitrous acid compound with an acid from the first reactor;
A feeding device for sending a reaction by-product containing nitric acid produced by reacting a nitrite compound with an acid from the first reactor to the second reactor;
A second outflow passage for letting out nitric oxide gas produced by reacting nitric acid contained in the reaction by-product with at least one of sulfur dioxide and sulfite compound from the second reactor; An apparatus for producing nitric oxide gas. An apparatus for producing nitric oxide gas for carrying out the method according to claim 3,
A reactor into which a nitrite compound, an acid, and at least one of sulfur dioxide and a sulfite compound are introduced;
Nitric oxide gas produced by reacting a nitrite compound with an acid, and nitrogen dioxide contained in a reaction by-product produced by reacting a nitrite compound with an acid, are contained in sulfur dioxide and sulfite compounds. An apparatus for producing nitric oxide gas, comprising: an outflow passage for causing nitric oxide gas generated by reacting with at least one to flow out of the reactor. The apparatus for producing nitric oxide gas according to claim 4 or 5, further comprising a gas scrubber that generates nitrogen monoxide gas by reducing nitrogen dioxide gas contained in the nitrogen monoxide gas with an aqueous solution of a sulfurous acid compound.

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