JP2000272907A - Production of chlorine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably produce chlorine in high yield while suppressing excessive hot spots in a catalyst packed bed by arranging two or more reactive catalyst packed beds for oxidizing hydrogen chloride included in a gas with a gas containing oxygen, in series, and carrying out the temperature control of one or more thereof by a heat-exchanging method. SOLUTION: Hydrogen chloride included in a gas is oxidized by a gas containing 0.25-2 mol oxygen per mol hydrogen chloride in the presence of a catalyst to produce the objective chlorine. The reaction zone is composed of at least two (preferably two to eight) catalyst packed beds arranged in series. The whole amount of the gas containing the hydrogen chloride and 5-90% of the whole amount of the gas containing the oxygen are introduced to the first reaction zone, and the gas containing the oxygen is separately introduced to the second reaction zone and the following. Reaction temperature is preferably 200-500 deg.C, and the temperature control of at least one of the reaction zones, (preferably the whole reaction zones) is carried out by a heat-exchanging method. As a result, excessive hot spots in the reaction zones are suppressed and stable activities of the catalyst are maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing chlorine. More specifically, the present invention relates to a method for producing chlorine, in which hydrogen chloride in a gas containing hydrogen chloride is oxidized using a gas containing oxygen. By making effective use of the bed, stable activity of the catalyst is maintained and chlorine can be obtained in a stable and high yield, so that catalyst cost, equipment cost, operation cost, stability and ease of operation The present invention relates to a very advantageous method for producing chlorine from the viewpoint of the above.

[0002]

2. Description of the Related Art It is well known that chlorine is useful as a raw material for vinyl chloride, phosgene and the like, and is obtained by oxidation of hydrogen chloride. For example, as a method for producing chlorine by catalytically oxidizing hydrogen chloride with molecular oxygen using a catalyst, a copper-based catalyst called a Deacon catalyst has been conventionally considered to have excellent activity, and copper chloride and potassium chloride have been conventionally used. Many catalysts in which various compounds are added as a third component have been proposed. In addition to the Deacon catalyst, a method using chromium oxide or this compound as a catalyst and a method using ruthenium oxide or this compound as a catalyst have been proposed.

However, the oxidation reaction of hydrogen chloride is 59%.
This is an exothermic reaction of kJ / mol-chlorine, and it is important to suppress excessive hot spots in the catalyst packed bed from the viewpoint of reducing thermal deterioration of the catalyst and ensuring stability and ease of operation. . Excessive hot spots can also cause runaway reactions in the worst case, and cause high temperature gas corrosion of equipment materials due to hydrogen chloride and / or chlorine.

The magazine “Catalyst” (Vol. 33 No. 1)
(1991)), in a reaction between pure hydrogen chloride and pure oxygen using chromium oxide as a catalyst, it is difficult to remove hot spots in a fixed-bed reaction mode, and a fluidized-bed reactor must be used in an actual apparatus. It is described.

[0005]

In such a situation,
The problem to be solved by the present invention is a method for producing chlorine, in which hydrogen chloride in a gas containing hydrogen chloride is oxidized using a gas containing oxygen, which suppresses excessive hot spots in the catalyst packed bed. By effectively utilizing the catalyst packed bed, stable activity of the catalyst is maintained, and chlorine can be obtained in a high yield stably, so that catalyst cost, equipment cost, operation cost, operation stability and An object of the present invention is to provide a method for producing chlorine which is extremely advantageous from the viewpoint of easiness.

[0006]

That is, the present invention relates to a method for producing chlorine by oxidizing hydrogen chloride in a gas containing hydrogen chloride using a gas containing oxygen in the presence of a catalyst,
The present invention relates to a method for producing chlorine, which has a reaction zone composed of at least two catalyst packed layers arranged in series, and controls the temperature of at least one of the reaction zones by a heat exchange method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The gas containing hydrogen chloride used in the present invention includes a pyrolysis reaction and a combustion reaction of a chlorine compound, a phosgenation reaction of an organic compound, a dehydrochlorination reaction or a chlorination reaction, and a combustion in an incinerator. Any substance including hydrogen chloride generated in the above method can be used. As a gas containing hydrogen chloride, the concentration of hydrogen chloride in the gas is usually 10% by volume or more, preferably 50% by volume or more,
More preferably, 80% by volume or more is used. When the concentration is lower than 10% by volume, when separating generated chlorine and / or recycling unreacted oxygen,
Recycling can be complicated. Components other than hydrogen chloride in the gas containing hydrogen chloride include chlorinated aromatic hydrocarbons such as orthodichlorobenzene and monochlorobenzene, aromatic hydrocarbons such as toluene and benzene, and vinyl chloride and 1,2-dichloroethane. Chlorinated aliphatic hydrocarbons such as methyl chloride, ethyl chloride, propyl chloride and allyl chloride; and aliphatic hydrocarbons such as methane, acetylene, ethylene and propylene; and nitrogen, argon, carbon dioxide, carbon monoxide, phosgene, Hydrogen, carbonyl sulfide,
Inorganic gas such as hydrogen sulfide; In the reaction between hydrogen chloride and oxygen, chlorinated aromatic hydrocarbons and chlorinated aliphatic hydrocarbons are oxidized to carbon dioxide, water and chlorine, and aromatic hydrocarbons and aliphatic hydrocarbons are converted to carbon dioxide and water. Oxidized, carbon monoxide is oxidized to carbon dioxide, and phosgene is oxidized to carbon dioxide and chlorine.

As the gas containing oxygen, oxygen or air is used. Oxygen can be obtained by ordinary industrial methods such as air pressure swinging and cryogenic separation.

The theoretical molar amount of oxygen to 1 mole of hydrogen chloride is 0.25 mole, but it is preferable to supply more than the theoretical amount, and more preferably 0.25 to 2 moles of oxygen to 1 mole of hydrogen chloride. If the amount of oxygen is too small, the conversion of hydrogen chloride may decrease, while if the amount of oxygen is excessive, it may be difficult to separate generated chlorine from unreacted oxygen.

In the present invention, it is preferred that a gas containing oxygen is divided and introduced into a reaction zone comprising at least two catalyst packed layers arranged in series. As a method of dividing and introducing the gas containing oxygen, the entire amount of the gas containing hydrogen chloride and a part of the gas containing oxygen are introduced into the first reaction zone, and the reactant and the remaining gas containing oxygen are introduced into the first reaction zone. There is a method of introducing the compound into the reaction zone after the second reaction zone. Here, the first
The reaction zone means the most upstream reaction zone for the flow of the raw material gas, and the second reaction zone means the downstream reaction zone of the first reaction zone. The division amount of the gas containing oxygen introduced into the first reaction zone is 5 to 90% of the total amount, preferably 10 to 80%.
%, More preferably 30 to 60%. If the amount of division is too small, it may be difficult to control the temperature of the reaction zone after the second reaction zone.

In the present invention, it is necessary to control the temperature of at least one of the reaction zones by a heat exchange method. As a result, by suppressing excessive hot spots in the reaction zone and effectively utilizing the reaction zone,
Since stable activity of the catalyst is maintained and chlorine can be obtained stably at a high yield, catalyst cost, equipment cost, operation cost, stability and ease of operation can be secured.

In the reaction zone comprising at least two catalyst packed layers arranged in series, the reaction tube is filled with at least two kinds of catalysts and / or the temperature of the reaction zone is controlled in at least two ways. Formed by Here, the reaction zone consisting of the catalyst-packed bed forms a fixed-bed reactor, and does not form a fluidized-bed reactor and a moving-bed reactor. As a method of filling at least two kinds of catalysts, a method of dividing a catalyst packed bed in a reaction tube into at least two sections in a tube axis direction and filling catalysts having different activities, compositions and / or particle diameters, or a method of filling catalysts Is diluted in at least two ways with a packing molded only with an inert substance and / or a carrier, or a catalyst and a catalyst are diluted with an inert substance and / or
Alternatively, there may be mentioned a method of filling a material diluted with a filler molded only with a carrier. The catalyst is inert and / or
Alternatively, in the case of dilution with a packing molded only with a carrier, the whole of the packed catalyst and an inert substance and / or a packing molded only with a carrier means a reaction zone including a catalyst packed layer. Usually, successive reaction zones are in direct contact with each other, but an inert substance may be filled between the reaction zones. However, a packed bed composed only of an inert substance is not considered as a catalyst packed bed. As a method of controlling the temperature of the reaction zone composed of the catalyst packed bed by at least two methods, a method of controlling the temperature by at least two independent methods can be mentioned. In this case, at least one type of temperature control needs to be performed by a heat exchange method.

The heat exchange method of the present invention means a method in which a jacket is provided outside a reaction tube filled with a catalyst, and heat of reaction generated by the reaction is removed by a heat medium in the jacket. In the heat exchange method, the temperature of a reaction zone formed of a catalyst packed bed in a reaction tube is controlled by a heat medium in a jacket. Industrially, a reaction tube having reaction zones consisting of catalyst packed layers arranged in series is arranged in parallel, and a fixed tube multi-tube reactor of a multi-tube heat exchanger type having a jacket portion on the outside is used. You can also. As a method other than the heat exchange method, there is an electric furnace method, but there is a problem that it is difficult to control the temperature of the reaction zone.

In the present invention, it is preferable to control the temperature of at least two of the reaction zones by a heat exchange method. As this method, a method in which a heating medium is independently circulated through at least two independent jacket portions to control the temperature of the reaction zone, and / or the jacket portion is divided into at least two by a partition plate and partitioned. A method of controlling the temperature of the reaction zone by circulating a heat medium independently in each part can be given. The partition plate may be directly fixed to the reaction tube by welding or the like, but in order to prevent thermal distortion from occurring in the partition plate and the reaction tube, within a range where the heat medium can be substantially independently circulated. An appropriate distance can be provided between the partition plate and the reaction tube.
Preferably, the flow of the heat medium in the jacket flows upward from below.

In the present invention, a method in which the temperature of the entire reaction zone is controlled by a heat exchange method is preferable because the reaction heat is removed well and the stability and operability of the operation are ensured.

The heat medium may be a molten salt, steam, an organic compound or a molten metal, but a molten salt or steam is preferred from the viewpoint of thermal stability and ease of handling, and more favorable thermal stability In view of this, a molten salt is more preferred. Molten metal has problems such as high cost and difficulty in handling. As the composition of the molten salt, a mixture of 50% by weight of potassium nitrate and 50% by weight of sodium nitrite,
53% by weight of potassium nitrate and 40% by weight of sodium nitrite
And 7% by weight of sodium nitrate. Examples of the organic compound include Dowsome A (a mixture of diphenyl oxide and diphenyl).

The larger the number of reaction zones, the more effectively the reaction zones can be utilized.
Reaction zone, preferably 2-8 reaction zones, more preferably 2-8
Performed in four reaction zones. If the number of reaction zones is too large, the type of catalyst to be charged may be increased and / or the equipment for temperature control may be increased, which may be economically disadvantageous.

In the present invention, the ratio of the first reaction zone in the reaction zone comprising at least two catalyst packed layers arranged in series is preferably 70% by volume or less, more preferably 30% by volume or less. Further, the ratio of the first reaction zone is set to 70
Volume% or less, preferably 30 volume% or less, and the second
The temperature of the reaction zone is usually at least 5 ° C., preferably at least 10 ° C. higher than the first reaction zone, and / or the activity of the second reaction zone is usually at least 1.1 times higher than that of the first reaction zone, preferably It is more preferable to fill a catalyst or a filler molded only with a catalyst and an inert substance and / or a carrier so that the pressure is 1.5 times or more. Here, the activity of the reaction zone (mol-HC
1 / ml-reaction zone · min) is the product of the hydrogen chloride reaction activity per unit catalyst weight and time (mol-HCl / g-catalyst · min) and the catalyst loading amount (g), and the volume of the reaction zone (g). ml) means the calculated value. The hydrogen chloride reaction activity per unit catalyst weight and time was as follows: the ratio of the catalyst volume to the supply rate of hydrogen chloride under standard conditions (0 ° C., 0.1 MPa) was 4400 to 4800 h ⁻¹ , A value calculated from the amount of chlorine generated at this time by reacting at a reaction pressure of 0.1 MPa and a reaction temperature of 280 ° C. by supplying 0.5 mol of oxygen. In the first reaction zone, the reaction rate is high due to the high concentration of the reactants, hydrogen chloride and oxygen, and a hot spot is generated on the inlet side of the first reaction zone.
On the other hand, the outlet side of the first reaction zone has a temperature close to the temperature of the heat medium in the jacket. 70% by volume in the first reaction zone
If it is larger, the catalyst packed layer portion at a temperature close to the temperature of the heat medium in the jacket increases in the reaction zone, and the catalyst cannot be used effectively.

As the catalyst for the oxidation reaction of the present invention, a known catalyst known as a catalyst for producing chlorine by oxidizing hydrogen chloride can be used. Examples of the catalyst include a catalyst obtained by adding various compounds as a third component to copper chloride and potassium chloride, a catalyst containing chromium oxide as a main component, a catalyst containing ruthenium oxide, and the like. Among them, a catalyst containing ruthenium oxide is preferable, and a catalyst containing ruthenium oxide and titanium oxide is more preferable. Catalysts containing ruthenium oxide are disclosed, for example, in JP-A-10-1821.
No. 04, EP 936184. Catalysts containing ruthenium oxide and titanium oxide are described, for example, in JP-A-10-194705 and JP-A-10-338502. The content of ruthenium oxide in the catalyst is preferably 0.1 to 20% by weight. If the amount of ruthenium oxide is too small, the activity of the catalyst may be low and the conversion of hydrogen chloride may be low. On the other hand, if the amount of ruthenium oxide is too large, the price of the catalyst may be high.

The catalyst may be used in the form of spherical granules, cylindrical pellets, extruded shapes, ring shapes, honeycomb shapes, or granules of an appropriate size which are pulverized and classified after molding. At this time, the catalyst diameter is preferably 10 mm or less. If the catalyst diameter exceeds 10 mm, the activity may be reduced. The lower limit of the catalyst diameter is not particularly limited. However, when the catalyst diameter is excessively small, the pressure loss in the catalyst packed bed increases. In addition,
The term "catalyst diameter" as used herein means the diameter of a sphere in the case of spherical particles, the diameter of a cross section in the case of a cylindrical pellet, or the maximum diameter of a cross section in other shapes.

In the present invention, it is preferable to fill a catalyst or a filler molded only with a catalyst and an inert substance and / or a carrier so that the thermal conductivity of the first reaction zone is the highest. It is more preferable to fill the reaction zone from the zone to the final reaction zone so that the thermal conductivity of the reaction zone decreases in the gas flow direction. Here, the final reaction zone means the most downstream reaction zone for the gas flow. The thermal conductivity of the reaction zone means the thermal conductivity of the packing filled in the reaction zone. In the reaction zone on the inlet side of the raw material, the reaction rate is high due to the high concentration of the reactants hydrogen chloride and oxygen,
Large heat generation due to oxidation reaction. Therefore, by filling the reaction zone on the inlet side with a catalyst having a relatively high thermal conductivity of the catalyst, an excessive hot spot in the catalyst packed layer can be suppressed.

In the present invention, from the first reaction zone to the final reaction zone, only the catalyst or the catalyst and the inert substance and / or the carrier are molded so that the activity of the reaction zone becomes higher in the gas flow direction. Filling with the filled packing is preferable because the temperature difference in the continuous reaction zone can be reduced, and thus the operation can be stably and easily performed.

In the present invention, the activity of the final reaction zone is
The catalyst or the packing molded only with the catalyst and the inert substance and / or the carrier is filled so that the activity is higher than the activity of the immediately preceding reaction zone, and the hot spot of the final reaction zone is filled with the hot spot of the immediately preceding reaction zone. A method of lowering the temperature than the hot spot is preferable. If the activity of the final reaction zone is lower than that of the previous reaction zone and the hot spot of the final reaction zone is higher than the hot spot of the immediately preceding reaction zone, hydrogen chloride is oxidized with oxygen and converted to chlorine and water. Since the reaction is an equilibrium reaction, the conversion of hydrogen chloride may be low due to the chemical equilibrium composition.

The amount (volume) of the catalyst used is in the standard state (0
In terms of the ratio (GHSV) to the supply rate of hydrogen chloride at 0.1 ° C. and 0.1 MPa), the reaction is usually performed at 10 to 20,000 h ⁻¹ . The direction in which the raw material flows into the reaction zone may be upward or downward. The reaction pressure is usually from 0.1 to 5 MPa. The reaction temperature is preferably from 200 to 500C, more preferably from 200 to 380C. If the reaction temperature is too low, the conversion of hydrogen chloride may decrease, while if the reaction temperature is too high, the catalyst components may volatilize.

In the present invention, a method in which the gas temperature at the outlet of the final reaction zone is set to 200 to 350 ° C. is preferable.
A method of setting the temperature to 0 to 320 ° C is more preferable. If the gas temperature at the outlet of the final reaction zone is higher than 350 ° C., the conversion of hydrogen chloride to oxygen and conversion to chlorine and water is an equilibrium reaction. May be dominated and lower.

In the present invention, the gas linear velocity based on the superficial tower is preferably from 0.2 to 10 m / s, and from 0.2 to 5 m / s.
m / s is more preferred. If the gas linear velocity is too low,
In order to obtain a satisfactory throughput of hydrogen chloride in an industrial reactor, an excessive number of reaction tubes may be required, which may be disadvantageous. Pressure loss may increase. In addition, the gas linear velocity based on the superficial tower of the present invention refers to a standard state (0 ° C., 0.1 MPa
It means the ratio of the sum of the supply rates of the gas containing hydrogen chloride and the gas containing oxygen in a) to the cross-sectional area of the reaction tube.

The inner diameter of the reaction tube is usually 10 to 50 mm, preferably 10 to 40 mm, more preferably 10 to 30 m.
m. If the inner diameter of the reaction tube is too small, it may be disadvantageous because an excessive number of reaction tubes is required in order to obtain a satisfactory throughput of hydrogen chloride in an industrial reactor. If the inner diameter is too large, an excessive hot spot may be generated in the catalyst packed bed.

The ratio (D / d) of the inner diameter (D) of the reaction tube to the catalyst diameter (d) is usually 5/1 to 100/1, preferably 5/1 to 50/1, more preferably 5/1. ２０20/1. When the ratio is too small, an excessive hot spot may be generated in the catalyst packed bed, and when the ratio is too large, the pressure loss of the catalyst packed bed may be large.

[0029]

The present invention will be described below with reference to examples. Example 1 A reactor equipped with a jacket using a molten salt (potassium nitrate / sodium nitrite = 1/1 weight ratio) having a diameter of 18 mm and a length of 1 m (temperature measuring sheath having an outer diameter of 5 mm) was used in a reactor. Tube). On the upper side of the reaction tube, 80.2 g (60.0 m) of a 6.6 wt% ruthenium oxide extrusion catalyst supporting α-Al ₂ O ₃ having a diameter of 1.5 mm was loaded.
1) was filled to form a first reaction zone. In addition, this catalyst,
What was used for about 260 hours in the oxidation reaction of hydrogen chloride was reused. At the lower side of the first reaction zone, 35.9 g (35.6 ml) of a 6.6 wt% ruthenium oxide spherical granular catalyst supporting anatase crystalline TiO ₂ having a diameter of 1 to 2 mm and a diameter of 2 mm
Α-Al ₂ O ₃ spheres (Nikkato Co., Ltd., SSA995)
37.6 g (17.8 ml) are mixed well and filled,
This was the second reaction zone. The catalyst filling length was (first reaction zone / second reaction zone) = 0.280 m / 0.235 m. The catalyst filling volume was 1 reaction zone / second reaction zone = 66 ml / 55 ml
The ratio of the first reaction zone is calculated to be 54% by volume. The 1.5-mm diameter α-Al ₂ O ₃ supported 6.6 wt% ruthenium oxide extrusion catalyst was prepared by the following method. That is, commercially available α-Al ₂ O ₃ powder (manufactured by Sumitomo Chemical Co., Ltd., AES-12), ruthenium chloride, pure water, and alumina sol (manufactured by Nissan Chemical Co., Ltd., alumina sol 20)
0) was mixed well. The mixture was blown with dry air at room temperature and dried to an appropriate viscosity. This mixture was extruded to a diameter of 1.5 mm. Then, it was dried in air at 60 ° C. for 4 hours. The obtained solid was heated from room temperature to 350 ° C. in 1 hour, and calcined at the same temperature for 3 hours,
There was obtained a 6.6 wt% ruthenium oxide extrusion catalyst supporting α-Al ₂ O _{3 having a} diameter of 1.5 mm. An anatase crystalline TiO ₂ supported 6.6 wt% ruthenium oxide spherical granular catalyst having a diameter of 1 to 2 mm was prepared according to the method described in JP-A-10-338502. Further, the hydrogen chloride reaction activity per unit catalyst weight and time per hour of the 6.6 wt% ruthenium oxide extrusion catalyst supporting α-Al ₂ O ₃ used in this example was 1.3 × 10 ⁻⁴ mol-HCl / g-. Catalyst ・ min
And measured by the following method. 14 mm inner diameter Pyrex glass reaction tube (outer diameter 4 mm sheath tube for temperature measurement)
Was charged with 4.0 g (3.3 ml) of the catalyst, and the temperature was 280 ° C.
Into a molten salt bath of 0.26 l / min hydrogen chloride
(Standard state), oxygen 0.13 l / min (standard state) was circulated from the upper part to the lower part by down flow, and after 1.5 h, the outlet gas was sampled in an aqueous potassium iodide solution,
Absorb the generated chlorine, unreacted hydrogen chloride and generated water,
The amount of chlorine produced and the amount of unreacted hydrogen chloride were measured by iodine titration and neutralization titration, respectively. The unit catalyst weight and hydrogen chloride reaction activity per unit time of the anatase crystalline TiO ₂ supported 6.6 wt% ruthenium oxide spherical granular catalyst are 4.8 × 10 ⁻⁴ mol-HCl / g-catalyst · min. 1.9 g (2.0 ml), 0.16 l / min of hydrogen chloride (standard condition), 0.08 l / m of oxygen
5. α-Al ₂ O ₃ supported except that in (standard state) was used.
The test was performed in accordance with a 6% by weight ruthenium oxide extrusion catalyst. The activity of the first reaction zone is 1.6 × 10 ⁻⁴ mol-HCl
/ Ml-reaction zone · min, the activity of the second reaction zone is 3.1 ×
It is calculated as 10 ⁻⁴ mol-HCl / ml-reaction zone · min. Gas containing hydrogen chloride 6.1 l / min (standard condition, hydrogen chloride: 99 volume% or more), oxygen 3.05 l / m
in (standard condition, oxygen: 99% by volume or more) was allowed to flow from the upper portion to the lower portion of the Ni-made reaction tube by downflow, and the reaction was performed with the temperature of the molten salt in the jacket at 326 ° C. The gas linear velocity based on the superficial tower is calculated to be 0.65 m / s.
The reaction temperature in the first reaction zone is 332 ° C. at the inlet, 335 ° C. at the outlet,
The hot spot was 347 ° C. The reaction temperature in the second reaction zone is 335 ° C. at the inlet, 338 ° C. at the outlet,
4 ° C. The outlet gas of the second reaction zone is sampled into an aqueous solution of potassium iodide to absorb generated chlorine, unreacted hydrogen chloride and generated water, and determine the amount of chlorine produced and the amount of chlorine by iodometric titration and neutralization titration, respectively. The amount of unreacted hydrogen chloride was measured. Conversion of hydrogen chloride to chlorine is 30.6%
Met.

Example 2 The reactor was equipped with an electric furnace and had an inner diameter of 26 mm and a length of 2.
0 m Ni reaction tube (outer diameter 6 mm sheath tube for temperature measurement) 1
Book and molten salt (potassium nitrate / sodium nitrite = 1 /
1 wt.
A fixed bed reactor in which a total of three reaction tubes consisting of two reaction tubes having a length of 2.5 mm and a length of 2.5 m (sheath tubes having an outer diameter of 6 mm) were connected in series was used. In a reaction tube having an inner diameter of 26 mm, 69 g (60 ml) of a 6.6 wt% ruthenium oxide extruded catalyst supporting α-Al ₂ O ₃ having a diameter of 1.5 mm and a diameter of 2
132 g (60 ml) of α-Al ₂ O ₃ spheres having a diameter of mm were sufficiently mixed and filled to form a first reaction zone. The first reaction tube having an inner diameter of 18 mm has an anatase crystal form T having a diameter of 1 to 2 mm.
6.6% by weight of ruthenium oxide spherical catalyst supported on iO ₂ 3
Α-Al ₂ O ₃ spheres 3 of 00 g (300 ml) and 2 mm in diameter
40 g (150 ml) was sufficiently mixed and filled to form a second reaction zone. In the second reaction tube having an inner diameter of 18 mm, 297 g (294 ml) of a 6.6 wt% ruthenium oxide spherical granular catalyst supporting anatase crystalline TiO ₂ having a diameter of 1 to 2 mm was used.
To form a third reaction zone. The catalyst filling length is: first reaction zone / second reaction zone / third reaction zone = 0.21 m / 1.98 m
/1.37 m. The catalyst loading volume is the first reaction zone /
2nd reaction zone / 3rd reaction zone = 103ml / 447ml / 3
At 09 ml, the proportion of the first reaction zone is calculated to be 12% by volume. The 6.6 wt% ruthenium oxide extrusion catalyst supporting α-Al ₂ O ₃ was prepared according to Example 1, and the amount of the catalyst used was changed to 4.0 g (3.5 ml).
The hydrogen chloride reaction activity per unit catalyst weight and time measured in accordance with the above was 2.5 × 10 ⁻⁴ mol-HCl / g-catalyst · min. The activity of the first reaction zone is 1.7 × 10
^-4 mol-HCl / ml-reaction zone · min, activity in the second reaction zone is 3.2 × 10 ^-4 mol-HCl / ml-reaction zone · min, activity in the third reaction zone is 4.6 × 10 ^-4 mol-
HCl / ml-reaction zone · min. Gas containing hydrogen chloride 6 l / min (standard condition, hydrogen chloride: 99 vol% or more), oxygen 1.13 l / min (standard condition, oxygen: 99 vol% or more), and unreacted oxygen obtained after separating chlorine 2.15 l / min (standard condition, oxygen: 86.0 vol%, chlorine: 8.9 vol% (calculated value), nitrogen: 2.3 vol%, argon: 2.7 vol% , Carbon dioxide: 0.1% by volume) from the upper part to the lower part of the Ni reaction tube in a downflow manner, the inlet pressure of the reactor was 1.19 kg / cm ² -G (corresponding to 0.22 MPa), and the electric furnace was At 342 ° C. and the temperature of the molten salt in the jacket at 345 ° C. and 332 ° C. for the reaction. The gas linear velocity based on a superficial tower is 0.31 in a reaction tube having an inner diameter of 26 mm.
m / s, calculated to be 0.68 m / s for a reaction tube having an inner diameter of 18 mm. The reaction temperature in the first reaction zone was 322 ° C. at the inlet and 3 at the outlet.
43 ° C., hot spot 344 ° C. The reaction temperature in the second reaction zone was 336 ° C. at the inlet, 348 ° C. at the outlet, and 362 ° C. in the hot spot. The reaction temperature in the third reaction zone is inlet 3
The temperature was 25 ° C, the outlet was 338 ° C, and the hot spot was 350 ° C. The gas obtained from the reaction was cooled and subsequently fed into the absorption tower. The absorption tower was provided with a pure water tank, a pure water feed pump, a 20 wt% hydrochloric acid feed pump, and a pump for circulating hydrochloric acid in the tower. Pure water is fed into the pure water tank at 0.15 kg / h (29 ° C.) using a pure water feed pump, and absorbed in the pure water tank before feeding to the absorption tower. After contact with the gas obtained from the top of the tower, the gas was fed from the tank to the bottom of the absorption tower by overflow. 20 wt% hydrochloric acid 0.355 kg / h (29
C.) was fed from the upper part of the absorption tower using a pump for a 20% by weight hydrochloric acid feed and brought into contact with the gas in a countercurrent manner.
A solution of hydrochloric acid (24.7% by weight of hydrogen chloride, 0.39% by weight of chlorine) in a tower containing hydrogen chloride and water as main components is circulated to the upper part of the absorption tower by a circulation pump, and is counter-flowed with gas. Was contacted. Also, the solution was supplied 0.736 from the circulation pump outlet.
It was withdrawn at a flow rate of kg / h. From the top, the temperature is 2
A gas at normal pressure of 8 ° C. was obtained. The gas obtained from the top of the absorption tower was passed through the sulfuric acid drying tower. In the sulfuric acid drying tower,
A sulfuric acid feed pump was installed. In the sulfuric acid drying tower, 98% by weight sulfuric acid 0.14 was added using a sulfuric acid feed pump.
5 kg / h was fed, and sulfuric acid in the tower was withdrawn at 0.172 kg / h by overflow. The obtained dry gas (water: 0.05 mg / l or less) was separated into mist by a mist separator, and then fed to a compressor, and then dried at 9.25 kg / l.
cm ² -G (equivalent to 1.01 MPa), followed by-
After cooling to 20 ° C., it was separated into a liquid mainly composed of chlorine and a gas mainly composed of unreacted oxygen. The composition of the obtained chlorine was as follows: chlorine: 98.6% by volume (calculated value), oxygen: 1.1% by volume, nitrogen: 0.17% by volume, argon: 0.07% by volume, carbon dioxide: 0.09% % By volume. The gas containing unreacted oxygen as the main component was recycled to the reaction.

[0031]

As described above, according to the present invention, there is provided a method for producing chlorine by oxidizing hydrogen chloride in a gas containing hydrogen chloride using a gas containing oxygen, the method comprising: By effectively controlling the catalyst packed bed, the stable activity of the catalyst can be maintained, and chlorine can be obtained in a stable and high yield. From the viewpoint of the stability and easiness of the production of chlorine.

Continued on the front page (72) Inventor Yasuhiko Mori 5-1 Sokai-cho, Niihama-shi, Ehime Sumitomo Chemical Industries, Ltd. (72) Inventor Masayuki Yoshii 5-1, Anesaki Beach, Ichihara-shi, Chiba Sumitomo Chemical Industries, Ltd. F term (reference) 4G069 AA03 BA01A BA01B BA04A BA04B BB04A BB04B BB08A BC03A BC31A BC50A BC50B BC58A BC70A BC70B BD12A CB81 DA06 EA02Y EA04Y EA18 EB14Y EB18Y EE08

Claims (2)

[Claims] 1. A method for producing chlorine in which hydrogen chloride in a gas containing hydrogen chloride is oxidized using a gas containing oxygen in the presence of a catalyst, comprising the steps of: A method for producing chlorine, comprising: a reaction zone; and controlling the temperature of at least one of the reaction zones by a heat exchange method. 2. The chlorine production according to claim 1, wherein the proportion of the first reaction zone which is the most upstream reaction zone of the reaction zone comprising at least two catalyst packed layers arranged in series is 70% by volume or less. Method.