TWI626983B - Wet flue gas desulfurization method from gas containing hydrogen sulfide - Google Patents

Abstract

The wet desulfurization method containing hydrogen sulfide gas of the present invention is carried out by contacting a hydrogen sulfide gas with a desulfurization catalyst solution, wherein the desulfurization catalyst solution is a desulfurization catalyst. The solution is dissolved in an alkaline solution, and at least one of methylhydroquinone and formamidine is used as the desulfurization catalyst.

Description

Wet desulfurization method containing hydrogen sulfide gas

FIELD OF THE INVENTION The present invention relates to a wet desulfurization method containing hydrogen sulfide gas, which removes hydrogen sulfide from a hydrogen sulfide-containing gas by a wet method, and uses the desulfurization catalyst to remove the hydrogen sulfide to sulfur or a sulfur-containing salt. It is recycled in other forms.

Background of the Invention As a main method for removing hydrogen sulfide from a hydrogen sulfide-containing gas including a coke oven gas by a wet method, there are a Takahax method and a Fumaks method. In either method, an apparatus including the absorption tower 1 and the regeneration tower 2 as shown in Fig. 1 is often used. The absorption tower 1 is in contact with the desulfurization catalyst solution 5 in which the hydrogen sulfide-containing gas 3 is dissolved in an alkaline solution. The regeneration tower 2 is in contact with the oxygen-containing gas 6 and the desulfurization catalyst solution 5.

In the absorption tower 1, by bringing the hydrogen sulfide-containing gas 3 into contact with the desulfurization catalyst solution 5, the hydrogen sulfide contained in the hydrogen sulfide-containing gas 3 is dissolved in the desulfurization catalyst solution 5. Thereby, hydrogen sulfide is removed from the hydrogen sulfide-containing gas 3 to form the purified gas 4. The hydrogen sulfide dissolved in the desulfurization catalyst solution 5 is oxidized by reacting with the desulfurization catalyst dissolved in the desulfurization catalyst solution 5 to become solid sulfur or a sulfur-containing salt or a sulfur-containing ion. At this time, the desulfurization catalyst itself is reduced and changes from the oxidant to the reducing body.

Further, in the regeneration tower 2, the oxygen-containing gas 6 is brought into contact with the desulfurization catalyst solution 5 in which the hydrogen sulfide is dissolved, so that the oxygen contained in the contact oxygen-containing gas 6 is dissolved in the desulfurization catalyst solution. 5. Thereby, the oxygen dissolved in the desulfurization catalyst solution 5 reacts with the reducing body desulfurization catalyst which is reacted with the hydrogen sulfide contained in the desulfurization catalyst solution 5. As a result, the desulfurization catalyst is returned to the oxidant, and is regenerated into a form capable of re-reacting with the hydrogen sulfide dissolved in the desulfurization catalyst solution 5.

The desulfurization catalyst is reciprocally reacted with the hydrogen sulfide or oxygen dissolved in the desulfurization catalyst solution 5 to be reused between the reduction body and the oxidant. The desulfurization catalyst solution 5 is recycled while being circulated between the absorption tower 1 and the regeneration tower 2. The desulfurization catalyst solution 7 in which the generated sulfur or the sulfur-containing salt or the sulfur-containing ion is dissolved is discharged to the outside of the system.

The Takahax method described in Patent Document 1 mainly uses an anthracene, a hydroquinone or a salt having a naphthalene having two aromatic rings, a fluorene or a phenanthrene skeleton having three aromatic rings, and exhibiting standard oxidation. A substance having a reduction potential E ₀ = 0.45 to 0.7 V is used as a desulfurization catalyst. In this case, since there are two or more aromatic rings in the molecule, the solubility in water is lowered. Therefore, a substance which has improved the solubility in water by introducing an acidic group such as a sulfonic acid or a carboxylic acid is used as a desulfurization catalyst.

Conventionally, in the Takahax method, 1,4-naphthoquinone-2-sulfonate or a reduced form thereof is usually used as a catalyst. The sulfhydryl group of the catalyst compound in the aqueous solution is repeatedly oxidized and reduced, and is transferred to and from the sodium 1,4-naphthoquinone-2-sulfonate and its reducing body, or to and from the 1,4-naphthoquinone-2-sulfonic acid ammonium. Between the reducing body and the reducing body, the hydrogen sulfide dissolved in the desulfurization catalyst solution is used as a solid sulfur or an aqueous solution containing a sulfur salt or a sulfur ion.

At the present time when the invention of Patent Document 1 is completed, the main purpose is to recover by solid sulfur, but the recovery of the value of the solid sulfur market, etc., recently, in the form of an aqueous solution containing a sulfur-containing salt or a sulfur-containing ion, is recovered. Gradually generalized. Non-Patent Document 1 is being developed for the development of a catalyst which is more easily recovered in an aqueous solution, and to carry out 1,2,4-trihydroxybenzene or 4-methylcatechol having only one aromatic ring. 1,2,4-trihydroxybenzene exhibits good desulfurization activity in a stable state, but is expensive and has practical problems. On the other hand, 4-methylcatechol is decomposed in the air in addition to being expensive, so it needs to be stored in an inert gas atmosphere, and the cost at the time of storage or transportation is large.

Further, the Fumaks method of Patent Document 2 is a wet desulfurization method containing hydrogen sulfide gas as shown in Fig. 1, which uses an aromatic polynitro compound or an aromatic polyoxy compound as a catalyst to desulfurize it. In the case of a catalyst, picric acid is usually used. The form of sulfur recovery is not only solid sulfur, but is also recovered in the form of an aqueous solution in which a sulfur-containing salt or a sulfur-containing ion is dissolved. Prior Technical Literature Patent Literature

Patent Document 1: Japanese Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. literature

Non-Patent Document 1: Uchida, Jinliuyitong, Kawada Tatsuya, Teraji Tatsujiro, Kojima Yuki, Ikeda, and Ichiro "The wet oxidation desulfurization method for 2-nitroso-1-naphthol-4-sulfonic acid" Fuel Association, Vol. 60, 1981, p.58-64

SUMMARY OF THE INVENTION Problems to be Solved by the Invention In either of the Takahax method and the Fumaks method, the form of the desulfurization catalyst and the form at the time of transportation are all aqueous solutions, so that the capacity is increased and the cost is consumed at the time of storage and transportation. The cost of such a problem. Therefore, a desulfurization catalyst is desired which is not in the form of an aqueous solution of a desulfurization catalyst at the time of storage and transportation, but is solid.

However, if the desulfurization catalyst of the Fumaks method, that is, bitter acid is dried and solidified, it is explosive. Therefore, when storing and transporting a large amount of bitter acid, it can only be operated in an aqueous solution state for safety reasons.

On the other hand, the desulfurization catalyst of the Takahax method has a possibility of solidification as described in Patent Document 3, but it is necessary to temporarily crystallize and crystallize it by salt solution. Therefore, the process for crystallizing the desulfurization catalyst of the Takahax method is complicated and has a problem of cost. Therefore, the current state cannot be used for production, and it is difficult to obtain it by solidification.

Further, 1,2,4-trihydroxybenzene, which is discussed in Non-Patent Document 1, is expensive to sell as a solid, and has practical problems. In the case of 4-methylcatechol, it is expensive and decomposes in the air, so it becomes necessary to store it in an inert gas atmosphere, and the cost at the time of storage and transportation is large.

In view of the above problems, an object of the present invention is to provide a wet desulfurization method containing hydrogen sulfide gas, which uses a desulfurization catalyst which can be operated in a solid state without explosion, which is a safety problem, low cost and easy It is obtained and has the same desulfurization performance as the conventional desulfurization catalyst. Means to solve the problem

In view of the above problems, the inventors of the present invention have intensively studied a catalyst which is less explosive and solid. As a result, it has been found that in the wet desulfurization method, if one of methylhydroquinone or toluquinone or both is used as a desulfurization catalyst, the desulfurization ability is high.

The present inventors conducted a discussion on a compound which can be operated in a solid state and has few aromatic rings from the viewpoint of the cost of storage and transportation. In Patent Document 1, in order to ensure water solubility, it is necessary to introduce an acidic group. However, it is understood that in the case of a compound having only one aromatic ring in the molecule, an aqueous solution can be obtained without introducing an acidic group. In addition, it has been confirmed that the active 1,2,4-trihydroxybenzene is not expensive, and it is difficult to put it practical from the viewpoint of cost because it is expensive. Therefore, when the gallic phenol having the same substituent and only the position of the functional group is different, it is understood that sufficient activity cannot be obtained. Therefore, it is obvious that not only the type of the simple functional group but also the positional relationship must be considered.

A compound in which a methyl group is substituted on hydroquinone or catechol, and in the same manner as 1,2,4-trihydroxybenzene, it can be handled in a solid state, and is excellent in terms of cost of storage and transportation. . Non-Patent Document 1 has been studied for 4-methylcatechol. However, 4-methylcatechol is an unstable compound and decomposes in the air. Therefore, it needs to be stored in an inert gas atmosphere and stored. And the cost of transportation will be huge.

Therefore, other compounds in which a methyl group is substituted on hydroquinone or catechol, that is, methylhydroquinone, are discussed. As a result, it was found that methylhydroquinone has sufficient activity. The reaction mechanism is shown in Fig. 2. It is presumed that, similarly to the conventional Takahax catalyst, reduction due to dissolved hydrogen sulfide (H ₂ S) 11 occurs in the sulfhydryl group, and oxygen (O ₂ ) 13 Oxidation is caused by the change between the oxime 9 of the oxidant and the methylhydroquinone 10 of the reducing body.

Therefore, it is also known that even if only one of formazan or methylhydroquinone is used in the reaction system, the sulfhydryl group of the catalyst is repeatedly oxidized and reduced, and becomes a reaction between the reductant and the reducing body. The system coexists and the desulfurization proceeds.

Further, methylhydroquinone is usually commercially available as a solid powder, and it is extremely easy to obtain. As a conventional use, there are a raw material of a polymer or a polymerization inhibitor, a polymerization inhibitor, a stabilizer, etc., and thus the market value is secured, and a relatively stable supply can be expected. It is also produced in large quantities, and can be obtained at a low price of about one-tenth of the 1,2,4-trihydroxybenzene and about one-fourth of the 4-methylcatechol. Further, methyl hydrazine, which is an oxidant of methylhydroquinone, is also widely used as a polymerization inhibitor and an oxidizing agent, and it is also possible to obtain a desulfurization catalyst in the form of an oxidant, thereby making it easier to obtain a desulfurization catalyst.

Thus, it has been found that in the wet desulfurization method, the problem of the present invention can be solved by using one or both of methylhydroquinone or formazan as a desulfurization catalyst, and the present invention has been completed.

(1) A wet desulfurization method containing hydrogen sulfide gas according to an aspect of the present invention, wherein the desulfurization of the hydrogen sulfide-containing gas is carried out by contacting a hydrogen sulfide-containing gas with a desulfurization catalyst solution The medium solution is obtained by dissolving a desulfurization catalyst in an alkaline solution, and the wet desulfurization method uses at least one of methylhydroquinone and formamidine as the desulfurization catalyst. (2) In the wet desulfurization method containing hydrogen sulfide gas described in the above (1), ammonia may be used as the alkali source of the alkaline solution. (3) In the wet desulfurization method containing hydrogen sulfide gas according to (1) or (2), the desulfurization catalyst solution may be at least one of the methylhydroquinone and the formazan The state is put into the aforementioned alkaline solution and dissolved to be produced. (4) In the wet desulfurization method containing hydrogen sulfide gas according to any one of the above (1) to (3), at least one of the methylhydroquinone and the formazan may be supplied in a solid state. To the aforementioned desulfurization catalyst solution, the aforementioned desulfurization catalyst is supplemented. (5) In the wet desulfurization method containing hydrogen sulfide gas according to any one of the above (1) to (4), the following may be employed: the desulfurization catalyst solution is used while the absorption tower and the regeneration tower are used. Desulfurization is performed while circulating between the absorption tower and the regeneration tower, and hydrogen sulfide in the hydrogen sulfide-containing gas is dissolved in the absorption tower by contacting the hydrogen sulfide-containing gas with the desulfurization catalyst solution. In the desulfurization catalyst solution, the hydrogen sulfide is removed from the hydrogen sulfide-containing gas to produce a purified gas, and the desulfurization catalyst solution in which the hydrogen sulfide is dissolved is circulated from the absorption tower to the regeneration tower. In the regeneration tower, an oxygen-containing gas is brought into contact with the desulfurization catalyst solution to generate sulfur, a sulfur-containing salt, or a sulfur-containing ion, and the sulfur, the sulfur-containing salt, or the sulfur-containing ion is recovered, and then The aforementioned desulfurization catalyst solution is recycled to the aforementioned absorption tower. (6) In the wet desulfurization method containing hydrogen sulfide gas according to the above (5), at least one of the methylhydroquinone and the formazan is supplied as a solid to the desulfurization catalyst in the regeneration tower. The solution is supplemented with the aforementioned desulfurization catalyst. Effect of the invention

According to the above aspects of the present invention, it is possible to provide a wet desulfurization method using hydrogen sulfide gas using one or both of methylhydroquinone or formazan as a desulfurization catalyst, and the desulfurization method used therefor The catalyst can be operated in a solid state, has no explosiveness, is easy to obtain at low cost, and has desulfurization performance equivalent to that of a conventional desulfurization catalyst.

MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described. As shown in Fig. 1, the wet desulfurization method of the present embodiment is basically constituted by two steps of an absorption step and a regeneration step, similarly to the conventional wet desulfurization method.

The first absorption step is a step of bringing the hydrogen sulfide contained in the hydrogen sulfide-containing gas 3 into contact with the alkaline desulfurization catalyst solution 5 and dissolving the hydrogen sulfide in the desulfurization catalyst solution 5, and is carried out in the absorption tower 1.

The hydrogen sulfide-containing gas 3 is mainly an exhaust gas discharged from various dry distillation furnaces, heating furnaces, power plants, etc., and is a gas containing about 10 ppm to 10,000 ppm of hydrogen sulfide. Further, the hydrogen sulfide-containing gas 3 has a high hydrogen sulfide removal rate from a problem in which the hydrogen sulfide gas is dissolved in an alkaline solution to a certain extent. Therefore, it is more preferable to contain 1000 ppm or more and 10000 ppm. The following gases of hydrogen sulfide. The hydrogen sulfide-containing gas 3 may further contain hydrogen, methane, carbon monoxide, carbon dioxide, nitrogen, ammonia, hydrogen cyanide or the like in addition to hydrogen sulfide. The coke oven gas discharged from the coke oven usually contains hydrogen sulfide in the above-described degree, and is a good example in which the hydrogen sulfide-containing gas 3 of the present embodiment is applied.

By bringing the desulfurization catalyst solution 5 into contact with the hydrogen sulfide-containing gas 3, the hydrogen sulfide contained in the hydrogen sulfide-containing gas 3 is dissolved in the desulfurization catalyst solution 5, but at this time, the cyanide contained in the hydrogen sulfide-containing gas 3 is contained. It is also possible to dissolve other acid gases such as hydrogen into the desulfurization catalyst solution 5, especially for the purpose of simultaneously removing hydrogen cyanide.

The desulfurization catalyst solution 5 in which hydrogen sulfide is dissolved by contact with the hydrogen sulfide-containing gas 3 is one in which one or both of methylhydroquinone or formazan is dissolved as a desulfurization catalyst in an alkaline solution. Founder. In this case, in order to obtain sufficient activity, the concentration of the desulfurization catalyst is preferably 0.01 mmol/L or more. Further, since the solubility of formazan in water is not large, the upper limit is preferably 100 mmol/L or less.

Further, in order to absorb hydrogen sulfide from the hydrogen sulfide-containing gas 3, the pH of the desulfurization catalyst solution 5 must be kept alkaline, but if it becomes too highly alkaline, the activity of the desulfurization catalyst is lowered. Therefore, the pH of the desulfurization catalyst solution 5 is preferably maintained in the range of 7.5 to 11.0.

By using one of methylhydrazine or formazan or both as a desulfurization catalyst, compared to, for example, the desulfurization catalyst using the Takahax method, that is, sodium 1,4-naphthoquinone-2-sulfonate In the existing sales form of 1,4-naphthoquinone-2-sulfonic acid sodium (1 mol/L sodium salt aqueous solution), about 1 mol of sodium 1,4-naphthoquinone-2-sulfonate is contained per 1 kg, Here, the methylhydroquinone powder contains 8 mol of methylhydroquinone per 1 kg. The molecule of any desulfurization catalyst carries one active site with respect to one molecule, and therefore, the methylhydroquinone powder per unit weight of the active site is relatively comparable to the 1,4-naphthylquinone which can be obtained. The aqueous solution of sodium -2-sulfonate is 8 times, and the cost of storage and transportation can be reduced. If thinking from this point of view, it is preferred that the number of rings is small and the number of substituents is small. In one or both of methylhydroquinone and formazan used in the present invention, the number of aromatic rings is one, and the substituent is also only one methyl group, which is effective for reducing storage and transportation costs.

As the alkali source constituting the alkaline solution of the desulfurization catalyst solution 5, sodium hydroxide, sodium carbonate, ammonia or the like can be used. In the present embodiment, one or both of methylhydroquinone or formazan, which is a desulfurization catalyst, does not contain an alkali metal. Therefore, in particular, by using ammonia as an alkali source, the desulfurization effect can be exerted by a desulfurization catalyst solution containing no alkali metal. In this case, after the process, the step of recovering the sulfate ion or its salt from the desulfurization catalyst solution 5 or the step of treating the desulfurization catalyst solution 5 as the waste liquid becomes unnecessary to be considered due to the alkali metal. Damage to the equipment, etc. Therefore, it becomes advantageous to relax the restrictions on equipment and mechanical work, and therefore it is preferable to use ammonia for the alkali source.

In the method of contacting the desulfurization catalyst solution 5 and the hydrogen sulfide-containing gas 3, the hydrogen sulfide-containing gas 3 may be introduced from the lower portion of the absorption tower 1, and the desulfurization catalyst solution 5 may be dispersed from the upper portion of the absorption tower 1. The method for absorbing hydrogen sulfide by the desulfurization catalyst solution 5. Alternatively, a method in which the desulfurization catalyst solution 5 is accumulated in the absorption tower 1 and the hydrogen sulfide-containing gas 3 is blown into the accumulated desulfurization catalyst solution 5 may be used. Further, the contact may be made by a method other than the above. When the hydrogen sulfide-containing gas 3 is introduced from the lower portion of the absorption tower 1 and the desulfurization catalyst solution 5 is dispersed from the upper portion of the absorption tower 1, the contact between the hydrogen sulfide-containing gas 3 and the desulfurization catalyst solution 5 is used. The area is increased, and a filler or the like can also be used.

The reproduction step will be described mainly with reference to Fig. 3. In order to clarify the correspondence relationship with Fig. 1, in the following description, the symbols in Fig. 1 are indicated by brackets. Further, Fig. 3 is a schematic view of a desulfurization apparatus having a regeneration tower provided with an input port of a solid desulfurization catalyst. In the regeneration step, the oxygen-containing gas 20 (6) is blown into the desulfurization catalyst solution 5 absorbing hydrogen sulfide to regenerate the desulfurization catalyst, and the hydrogen sulfide dissolved in the desulfurization catalyst solution 5 is made into sulfur or A step of containing a sulfur salt or a sulfur-containing ion. The regeneration step is carried out in the regeneration column 19 (2). The oxygen-containing gas 20 is required for oxidizing methylhydroquinone to formamidine, and air, oxygen, or oxygen-enriched air may be used.

The action of the oxidized body which is a desulfurization catalyst in the desulfurization catalyst solution 5, that is, formazan, and the methyl hydrazine which is a reducing body is described. In the absorption tower 16 (1), if hydrogen sulfide is dissolved in the alkaline solution containing the desulfurization catalyst, the formamidine in the desulfurization catalyst solution 5 reacts with hydrogen sulfide to become methylhydroquinone. In the absorption tower 16, the amount of hydrogen sulfide dissolved in the alkaline solution becomes higher than the concentration of the desulfurization catalyst, so that the desulfurization catalyst in the desulfurization catalyst solution 5 taken out from the absorption tower 16 is mostly turned into a The hydroquinone is sent to the regeneration tower 19 when the treatment of the total amount of hydrogen sulfide is not completed. In the regeneration tower 19, as described above, by blowing the oxygen-containing gas 20, methylhydroquinone reacts with oxygen in the oxygen-containing gas to form formazan, and thus it is possible to react with hydrogen sulfide again.

The desulfurization catalyst introduced into the desulfurization catalyst solution 5 of the regeneration tower 19 from the absorption tower 16 is mostly methylhydroquinone as described above, but the reaction with oxygen is repeated in the regeneration tower 19 and In the reaction with hydrogen sulfide, if the amount of hydrogen sulfide in the desulfurization catalyst solution 5 is gradually reduced, the formazan becomes unable to react with hydrogen sulfide. On the other hand, since oxygen is supplied at any time and only the reaction of methylhydroquinone to formamidine is carried out, the proportion of formazan in the desulfurization catalyst in the desulfurization catalyst solution 5 gradually increases. The desulfurization catalyst solution 5 in which the proportion of formazan is increased is sent from the regeneration tower 19 to the absorption tower 16 to be reused. Therefore, a part of the hydrogen sulfide in the desulfurization catalyst solution 5 is oxidized in the absorption tower 16, but most of it is oxidized in the regeneration tower 19 to become sulfur or a sulfur-containing salt or a sulfur-containing ion.

In addition, as the above-described mechanism, the desulfurization catalyst dissolved in the desulfurization catalyst solution 5 may be either methylhydroquinone or formamidine or both. This is because the absorption tower 16 and the regeneration tower 19 are stabilized in the above-described existence form depending on the reaction.

The method of contacting the desulfurization catalyst solution 5 with the oxygen-containing gas 20 may be a method in which the desulfurization catalyst solution 5 is accumulated in the regeneration tower 19, and the oxygen-containing gas 20 is blown into the accumulated desulfurization catalyst solution 5. Alternatively, the oxygen-containing gas 20 is taken in from the lower portion of the regeneration tower 19, and the desulfurization catalyst solution 5 is dispersed from the upper portion of the regeneration tower 19, and the desulfurization catalyst solution 5 is absorbed by the hydrogen sulfide, and the other methods are also can.

In the apparatus for performing the absorption step and the regeneration step, as described above, the absorption tower 16 (1) and the regeneration tower 19 (2) may be separately configured. As shown in Fig. 4, if it is considered to be blown in, When the hydrogen sulfide-containing gas 24 is not mixed with the oxygen-containing gas 30, it may be carried out by using one device having both the function of the regeneration tower and the absorption tower (for example, see Patent Document 4).

In Fig. 4, the upper portion of the partition wall 27 provided in the tower functions as an absorption tower, and an absorption step is performed on the upper portion. Further, the lower portion of the partition wall 27 functions as a regeneration tower, and a regeneration step is performed. Further above the partition wall 27, the hydrogen sulfide-containing gas 24 is blown in from a position close to the partition wall 27. Then, the desulfurization catalyst solutions 28, 31 in which the desulfurized catalyst to be recycled is dissolved are dispersed from the upper portion in the column, thereby making contact with the hydrogen sulfide-containing gas 24. As a result, the hydrogen sulfide in the hydrogen sulfide-containing gas 24 is absorbed by the desulfurization catalyst solutions 28 and 31, and the hydrogen sulfide-containing gas 24 from which hydrogen sulfide has been removed is recovered as a purified gas 25 from the top of the column. At this time, in order to increase the contact area between the hydrogen sulfide-containing gas 24 and the desulfurization catalyst solutions 28 and 31, the introduction portion of the hydrogen sulfide-containing gas 24 at the upper portion of the column and the outlet portion of the purified gas 25 may be A filler layer 26 is provided. The desulfurization catalyst solutions 28, 31 absorbing hydrogen sulfide are stored along the partition wall 27 and are stored in the lower portion of the tower via the sealed tank 29. The oxygen-containing gas 30 is blown into the desulfurization catalyst solution 28 accumulated in the lower portion of the column to regenerate the desulfurization catalyst. After the oxygen-containing gas 30 has passed through the desulfurization catalyst solution 28, it is discharged as the exhaust gas 33. The desulfurization catalyst solutions 28 and 31 accumulated in the lower portion of the tower are taken out from the lower portion of the tower and introduced from the upper portion of the tower by the liquid feeding pump 32, thereby being recycled. The hydrogen sulfide-containing gas 24 blown in by the partition wall 27 and the sealed can 29 is not mixed with the oxygen-containing gas 30.

When the solid desulfurization catalyst of the present embodiment is introduced into the desulfurization catalyst solution 5, 28, and 31 in the apparatus, it may be dissolved in water or an alkaline solution to be used as an aqueous solution before being added to the solution. Desulfurization catalyst solution 5, 28, 31 in the equipment. Alternatively, a solid desulfurization catalyst may be directly introduced into the desulfurization catalyst solution 5, 28, 31 in the apparatus. When the solid desulfurization catalyst is directly supplied to the desulfurization catalyst solution 5, 28, and 31 in the apparatus, it is not necessary to form the solid desulfurization catalyst into an aqueous solution, thereby preventing the step from being complicated. good.

The desulfurization catalyst slowly disappears due to deterioration or discharge of a part of the desulfurization catalyst solution in the step of recovering sulfur or sulfur-containing salt or sulfur-containing ions, and thus is preferably continuously or intermittently replenished during operation of the apparatus. In the replenishment, it is appropriate to consider the discharge amount of the desulfurization catalyst solution 5, 28, 31 in the cycle, the composition of the discharged solution, and the oxidation-reduction potential of the desulfurization catalyst solution 5, 28, 31 in the cycle. The amount of desulfurization catalyst added can be timely.

Further, when a solid desulfurization catalyst is directly charged, it is necessary to provide an input port for input into the apparatus. For example, a method in which the regeneration tower 19 and the absorption tower 16 are separately formed, a desulfurization catalyst solution 5 is accumulated in the regeneration tower 19, and the oxygen-containing gas 20 is blown into the accumulated desulfurization catalyst solution 5 is as shown in the figure. In the case of the general situation, it is preferable to directly provide the inlet port 21 into which the solid desulfurization catalyst is introduced in the upper portion of the regeneration tower 19. The desulfurization catalyst solution 5 accumulated in the regeneration tower 19 occupies most of the desulfurization catalyst solution 5 circulating between the devices, and the aeration gas 20 is blown in, and the stirring is promoted. The desulfurization catalyst is efficiently dissolved and diffused into the desulfurization catalyst solution 5.

Further, when the solid desulfurization catalyst of the present embodiment is introduced into the desulfurization catalyst solution 5 in the apparatus, the desulfurization catalyst solution 5 may contain other catalyst. For example, when the conventional wet desulfurization apparatus is used to carry out the method of the present embodiment, the desulfurization catalyst solution 5 already contains the desulfurization catalyst 1,4-naphthoquinone-2 used in the conventional Takahax method. The sulfonate and the reduced form thereof may be added to the solution in such a manner that a solid desulfurization catalyst according to the present embodiment is gradually added.

[Examples] [Comparative Example 1] As shown in Fig. 5, 400 mL of the simulated reaction liquid 35 was placed in a 500 mL beaker 34, and the simulated reaction liquid 35 was stirred while passing through a cylindrical gas injection pipe 37 with a magnetic stirrer 36. L/min was blown into the air to see the reaction. The composition of the reaction liquid 35 was simulated, and as a substitute for dissolved hydrogen sulfide, NaSH was set to a concentration of 10 mmol/L, and the desulfurization catalyst 1,4-naphthoquinone-2-sulfonic acid sodium of the Takahax method was set to 0.2 mmol. /L concentration. Since hydrogen sulfide is dissolved in an alkaline solution, it becomes a hydrogen sulfide ion. Therefore, when aqueous solution is used, sodium ion and ionized NaSH are used as a substitute for hydrogen sulfide. Since the pH of the simulated reaction liquid 35 is adjusted to be in the range of 7.5 to 11.0 due to the basicity of NaSH, the pH adjustment by the alkali source is not performed. In order to make the evaluation of the activity by the desulfurization catalyst constant, the temperature of the reaction liquid was kept constant at 30 ° C using a hot water bath 40. Further, this test is a batch test and is carried out under the condition that the concentration of hydrogen sulfide ions in the simulated reaction liquid 35 is continuously decreased.

During the reaction time of 1 hour and 30 minutes, sampling of the simulated reaction solution 35 was performed a plurality of times, and the hydrogen sulfide ion concentration according to the capillary electrophoresis apparatus was measured. Then, the rate of reduction of hydrogen sulfide ions was 1.50 ^{mmol·L -1} ·hr ^-1 from the change in the concentration of hydrogen sulfide ions over time. Furthermore, the relationship between the concentration of hydrogen sulfide ions and the reaction time is linearly approximated by the least squares to obtain the magnitude of the negative slope, which is obtained from the magnitude of the obtained slope minus the same experiment without placing the catalyst. The magnitude of the slope is determined as the reduction rate of hydrogen sulfide ions.

[Example 1] The same experiment as in Comparative Example 1 was carried out by placing a solid methylhydroquinone in place of sodium 1,4-naphthoquinone-2-sulfonate and dissolving it in the simulated reaction liquid 35. The concentration, the alkali source, and the reaction temperature were the same as in Comparative Example 1. At this time, 1.81 ^{mmol·L -1} ·hr ^{-1 was obtained} as a reduction ratio of hydrogen sulfide ions. This means that methylhydroquinone can have a hydrogen sulfide ion treatment ability equivalent to or higher than that of the conventional Takahax catalyst 1,4-naphthoquinone-2-sulfonate.

[Example 2] The same experiment as in Comparative Example 1 was carried out by placing inmazan instead of sodium 1,4-naphthoquinone-2-sulfonate. The concentration, the alkali source, and the reaction temperature were the same as in Comparative Example 1. At this time, 1.63 ^{mmol·L -1} ·hr ^{-1 was obtained} as a reduction ratio of hydrogen sulfide ions. This indicates that the formazan which is an oxidized body of methylhydroquinone has a hydrogen sulfide ion treatment ability equal to or higher than that of the conventional Takahax catalyst 1,4-naphthoquinone-2-sulfonic acid sodium, and represents a methyl group as a reducing body. Any form of hydroquinone or oxidized formamidine can be used as a desulfurization catalyst by putting it into the system.

[Comparative Example 2] The same experiment as in Comparative Example 1 was carried out by placing hydroquinone instead of sodium 1,4-naphthoquinone-2-sulfonate. The concentration, the alkali source, and the reaction temperature were the same as in Comparative Example 1. At this time, the reduction rate of hydrogen sulfide ions was 1.02 ^{mmol·L -1} ·hr ^-1 . This indicates that hydroquinone having one of the simplest compounds having a mercapto group cannot obtain the same performance as the conventional Takahax catalyst sodium 1,4-naphthoquinone-2-sulfonate.

[Comparative Example 3] The same experiment as in Comparative Example 1 was carried out by placing catechol instead of sodium 1,4-naphthoquinone-2-sulfonate. The concentration, the alkali source, and the reaction temperature were the same as in Comparative Example 1. At this time, the reduction ratio of hydrogen sulfide ions was 0.87 ^{mmol·L -1} ·hr ^-1 . This indicates that catechol having one of the simplest compounds having a mercapto group cannot obtain the same performance as the conventional Takahax catalyst 1,4-naphthoquinone-2-sulfonate.

[Comparative Example 4] The same experiment as in Comparative Example 1 was carried out by placing sodium 1,2-naphthoquinone-4-sulfonate instead of sodium 1,4-naphthoquinone-2-sulfonate. The concentration, the alkali source, and the reaction temperature were the same as in Comparative Example 1. At this time, the reduction ratio of hydrogen sulfide ions was 1.46 ^{mmol·L -1} ·hr ^-1 . This means that sodium 1,2-naphthoquinone-4-sulfonate has the same hydrogen sulfide ion treatment ability as the conventional Takahax catalyst 1,4-naphthoquinone-2-sulfonic acid sodium. However, since the amount of the active site per unit weight is 0.477 times that of methylhydroquinone, the methylhydroquinone used in the present invention can obtain the same activity as the conventional one at a lower weight.

[Comparative Example 5] The same experiment as in Comparative Example 1 was carried out by placing 1,2,4-trihydroxybenzene in place of sodium 1,4-naphthoquinone-2-sulfonate. The concentration, the alkali source, and the reaction temperature were the same as in Comparative Example 1. At this time, the reduction ratio of hydrogen sulfide ions was 1.53 mmol·L ^-1 ·hr ^-1 . This means that 1,2,4-trihydroxybenzene can have the same hydrogen sulfide ion treatment ability as the conventional Takahax catalyst 1,4-naphthoquinone-2-sulfonic acid sodium. However, if it is more expensive than methylhydroquinone, the methylhydroquinone used in the present invention can obtain the same activity as conventionally obtained at a relatively low cost.

[Comparative Example 6] The same experiment as in Comparative Example 1 was carried out by placing 4-methylcatechol instead of sodium 1,4-naphthoquinone-2-sulfonate. The concentration, the alkali source, and the reaction temperature were the same as in Comparative Example 1. At this time, the reduction ratio of hydrogen sulfide ions was 1.72 ^{mmol·L -1} ·hr ^-1 . This means that 4-methylcatechol can have the same hydrogen sulfide ion treatment ability as the conventional Takahax catalyst 1,4-naphthoquinone-2-sulfonic acid sodium. However, if it is expensive compared with methylhydroquinone, the methylhydroquinone used in the present invention can obtain the same activity as conventionally. Moreover, 4-methyl catechol needs to be stored in an inert gas environment due to stability problems, and the storage cost is large.

[Comparative Example 7] The same experiment as in Comparative Example 1 was carried out by placing gallicol instead of sodium 1,4-naphthoquinone-2-sulfonate. The concentration, the alkali source, and the reaction temperature were the same as in Comparative Example 1. At this time, the reduction ratio of hydrogen sulfide ions was 0.03 ^{mmol·L -1} ·hr ^-1 . This indicates that gallicol does not have hydrogen sulfide ion treatment ability, and if it has the same functional group as compared with the result of 1,2,4-trihydroxybenzene, there is a difference in hydrogen sulfide ion treatment ability due to its position.

[Comparative Example 8] An experimental apparatus is shown in Fig. 6 . The absorption tower 42 is a charging tower in which a 10 mmφ Raschig ring is placed at a height of 750 mm in a glass tower having a column diameter of 60 mm and a height of 900 mm. The regeneration tower 48 is a bubble column made of glass having a column diameter of 80 mm and a height of 1300 mm, and a cylindrical gas injection pipe is used for the gas injection port, and the effective liquid height is 1000 mm. Further, a 10 L glass bottle was used as the circulating liquid tank 45 for the experiment.

The composition of the simulated gas 41 was prepared by supplying nitrogen gas containing 10000 ppm of ammonia and 5000 ppm of hydrogen sulfide, and blowing from the lower portion of the absorption tower 42 at 0.8 Nm ³ /hr. Further, the flow rate of the air 49 blown from the lower portion of the regeneration tower 48 was set to 50 NL/hr. The simulated reaction liquid 46 was circulated in the system by a liquid supply pump 47 at a flow rate of 45 L/hr. The simulated reaction liquid 46 was adjusted to a concentration of 2 mmol/L of the desulfurization catalyst 1,4-naphthoquinone-2-sulfonic acid sodium of the Takahax method, and the initial pH was adjusted to 9.0 using ammonia water as an alkali source. The alkali source after the start of the test was set to be only the ammonia contained in the pseudo-gas 41, and pH 値 adjustment other than the other was not performed.

The gas chromatograph 44 using the flame photometric detector measures the hydrogen sulfide concentration of the treated purified gas 43 from the upper portion of the absorption tower 42 at regular intervals, and obtains the hydrogen sulfide removed from the introduced hydrogen sulfide. The ratio of the concentration, that is, the hydrogen sulfide removal rate. As a result, after 5 hours from the start of the test, the hydrogen sulfide removal rate was 100.0%, and after 15 hours, the hydrogen sulfide removal rate was 99.2%.

[Example 3] The same experiment as in Comparative Example 8 was carried out by placing methylhydroquinone instead of sodium 1,4-naphthoquinone-2-sulfonate. The experimental equipment, concentration, alkali source, and reaction temperature were all the same as in Comparative Example 8. At this time, the hydrogen sulfide removal rate was 99.8% and 99.4%, respectively, 5 hours after the start of the test and 15 hours later. This means that methylhydroquinone has the same hydrogen sulfide ion treatment ability as the conventional Takahax catalyst 1,4-naphthoquinone-2-sulfonic acid sodium.

[Comparative Example 9] The same experiment as in Comparative Example 8 was carried out by placing hydroquinone instead of sodium 1,4-naphthoquinone-2-sulfonate. The experimental equipment, concentration, alkali source, and reaction temperature were all the same as in Comparative Example 8. At this time, the hydrogen sulfide removal rate was 87.3% and 62.8%, respectively, 5 hours after the start of the test and 15 hours later. This indicates that hydroquinone cannot obtain the same performance as the conventional Takahax catalyst 1,4-naphthoquinone-2-sulfonic acid sodium. It is presumed that hydrogen sulfide dissolved in an alkaline solution in a simulated reaction liquid is not sufficiently treated by a catalyst to accumulate in an alkaline solution, and as a result, hydrogen sulfide cannot be sufficiently absorbed.

[Example 4] When the composition of the simulated gas in the same experiment as in Example 3 was set to nitrogen containing 12,000 ppm of ammonia, 4000 ppm of hydrogen sulfide, 1000 ppm of hydrogen cyanide, 25,000 ppm of carbon dioxide, and 3000 ppm of methane, hydrogen sulfide after 5 hours The removal rate was 99.2%. This means that the other acid gases contained in the coke oven gas, that is, hydrogen cyanide and carbon dioxide, or the hydrocarbon gas contained in the coke oven gas, that is, methane, do not affect the desulfurization performance.

[Example 5] In the same experiment as in Example 3, after 5 hours after the start of the test, the flow of the simulated gas, the circulation of the liquid, and the blowing of the air were stopped once, and 2 L of the simulated reaction liquid was taken out from the circulating liquid tank, and 2 L was introduced. The diluted ammonia water was used to bring the pH to 9.0. Further, the solid desulfurization catalyst inlet port 50 in the upper portion of the regeneration tower was directly solid powder, and 497 mg of methylhydroquinone was charged to the solution accumulated in the regeneration tower. Thereafter, the flow of the simulated gas, the circulation of the liquid, and the blowing of the air were started again, and after 2 hours from the start of the restart, the hydrogen sulfide removal rate was 99.5%. This means that even if it is directly put into a solid powder, it does not affect the desulfurization performance. Industrial availability

According to the present invention, it is possible to provide a wet desulfurization method containing a hydrogen sulfide gas, which uses a desulfurization catalyst which can be operated in a solid state and has no explosiveness, and is easily obtained at a low cost. It has the same desulfurization performance as the conventional desulfurization catalyst.

1, 16, 42‧‧ absorbing tower

2, 19, 48‧ ‧ regenerative tower

3, 15, 24‧‧‧ Containing hydrogen sulfide gas

4, 17, 25, 43‧‧ ‧ purified gas

5, 28, 31‧‧‧ Desulfurization catalyst solution

6, 20, 30‧‧‧ Oxygen-containing gas

7, 23‧‧‧Sulphur or a desulfurization catalyst solution containing sulfur or sulfur ions

8, 22, 33, 51‧‧‧ exhaust

9‧‧‧ Hyperthyroidism (oxidation)

10‧‧‧Methylhydroquinone (reducing body)

11‧‧‧ Hydrogen sulfide

12‧‧‧Sulphur

13‧‧‧Oxygen

14‧‧‧ water

18, 32, 47‧‧‧ liquid pump

21, 50‧‧‧ input port for solid desulfurization catalyst

26‧‧‧Filling agent

27‧‧‧ partition wall

29‧‧‧Sealed cans

34‧‧‧500mL beaker

35, 46‧‧‧ simulated reaction solution

36‧‧‧Magnetic mixer

37‧‧‧Cylinder gas injection pipe

38‧‧‧pH/ORP meter

39‧‧‧Dissolved Oxygen Analyzer

40‧‧‧Hot bath

41‧‧‧ Containing hydrogen sulfide gas (simulated gas)

44‧‧‧Gas Chromatograph with Flame Photometric Detector

45‧‧‧Circulating tank

49‧‧‧ Air

Fig. 1 is a schematic configuration diagram of a wet desulfurization method using a hydrogen sulfide gas using a general desulfurization catalyst. 2 is a tentative reaction formula of methylhydroquinone and formazan, and hydrogen sulfide (H ₂ S) and oxygen (O ₂ ). Fig. 3 is a schematic view of a desulfurization apparatus having a regeneration tower provided with an input port of a solid desulfurization catalyst. Fig. 4 is a schematic view of a desulfurization apparatus having both the function of an absorption tower and a regeneration tower. Fig. 5 is a schematic view showing a desulfurization catalyst activity evaluation test apparatus used in Examples 1 and 2 and Comparative Examples 1 to 7. Fig. 6 is a schematic view showing the desulfurization test apparatus used in Examples 3 to 5 and Comparative Examples 8 and 9.

Claims (7)

A wet desulfurization method containing hydrogen sulfide gas, characterized in that desulfurization of the hydrogen sulfide-containing gas is carried out by contacting a hydrogen sulfide-containing gas with a desulfurization catalyst solution, and the desulfurization catalyst solution is a desulfurization catalyst The medium is dissolved in an alkaline solution, and the wet desulfurization method uses at least one of methylhydroquinone and formamidine as the above-mentioned desulfurization catalyst. A wet desulfurization method containing hydrogen sulfide gas according to claim 1, which uses ammonia as an alkali source of the aforementioned alkaline solution. The wet desulfurization method containing hydrogen sulfide gas according to claim 1 or 2, wherein the desulfurization catalyst solution is at least one of the methylhydroquinone and the aforementioned formazan, and is supplied to the alkaline solution in a solid state. It is made by dissolving it. A wet desulfurization method containing hydrogen sulfide gas according to claim 1 or 2, wherein at least one of the methylhydroquinone and the aforementioned formazan is supplied to the desulfurization catalyst solution in a solid state to supplement the Sulfur catalyst. The wet desulfurization method containing hydrogen sulfide gas according to claim 3, wherein at least one of the methylhydroquinone and the aforementioned formazan is supplied to the desulfurization catalyst solution in a solid state, and the desulfurization catalyst is supplemented. . A wet desulfurization method containing hydrogen sulfide gas, characterized in that it is a wet desulfurization method containing hydrogen sulfide gas according to any one of claims 1 to 5, which uses an absorption tower and a regeneration tower, and Desulfurization is performed between the absorption tower and the regeneration tower while circulating the desulfurization catalyst solution. In the absorption tower, the hydrogen sulfide-containing gas is contacted with the desulfurization catalyst solution, and the hydrogen sulfide in the hydrogen sulfide-containing gas is dissolved in the desulfurization catalyst solution to be removed from the hydrogen sulfide-containing gas. Producing a purified gas by using the hydrogen sulfide, and circulating the desulfurization catalyst solution in which the hydrogen sulfide is dissolved from the absorption tower to the regeneration tower, and contacting the oxygen-containing gas with the desulfurization catalyst solution in the regeneration tower. Sulfur, a sulfur-containing salt or a sulfur-containing ion is generated, and the sulfur, the sulfur-containing salt or the sulfur-containing ion is recovered, and then the desulfurization catalyst solution is recycled to the absorption tower. A wet desulfurization method containing a hydrogen sulfide gas according to claim 6, wherein at least one of the methylhydroquinone and the formazan is supplied to the desulfurization catalyst solution as a solid in the regeneration tower. The aforementioned desulfurization catalyst.