JPH01257102A - Production of chlorine from hydrogen chloride - Google Patents

Abstract

PURPOSE:To stably obtain Cl2 in a high space-time yield over a long period when HCl is oxidized with molecular O2 in a fluidized bed reactor packed with a specified catalyst to produce Cl2, by bringing HCl and molecular O2 into a reaction in a specified molar ratio of HCl/O2. CONSTITUTION:Copper chloride or copper oxide, an alkali metal halide such as KCl and a halide or compd. of a rare earth element such as LaCl3 are supported on a carrier such as silica gel to prepare a catalyst. This catalyst is packed into a fluidized bed reactor and heated to 350-400 deg.C from the outside with a fluidized sand bath or the like. In the reactor, HCl and molecular O2 are brought into a reaction in 1/(0.5-2) molar ratio of HCl/O2 to oxidize the HCl with the molecular O2 by throughput of 400-1,000Nl/kg.h HCl.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is directed to a method for producing mM chlorine by oxidizing a chlorinated water gas with molecular oxygen. In particular, the present invention relates to a method of obtaining chlorine at a high space-time yield (hereinafter referred to as high STY) using a fluidized bed reactor, and also operating the fluidized bed catalyst bed stably over a long tI period.

The technical background of the present invention is as follows. Chlorine is produced industrially through the electrolysis of table salt, and although the demand for chlorine is increasing year by year, the amount of caustic soda produced during the electrolysis of table salt is less than that of chlorine, so the imbalance can be corrected by
The situation is difficult to correct. On the other hand, since human hydrogen chloride is produced as a by-product during the chlorination reaction of filN compounds or when using phosgene,
Since the demand for fj is significantly higher than the demand for 25 products, it is difficult to correct this imbalance. The chloride water system of the person 111 is unused and wasted, and a large amount of cost is also spent on the disposal 5611'. Therefore, if chlorine can be efficiently recovered from the hydrogen chloride that is being disposed of by humans, it will be possible to correct the imbalance with the production of caustic soda and meet the demand for salt.

Conventional technology> The reaction of producing chlorine by oxidizing hydrogen chloride has been around for a long time 1)
This is known as the e scon reaction.

In 1868, a copper-based catalyst invented by Qeacon
Conventional amounts are considered to be catalysts that exhibit excellent activity, and many catalysts have been proposed in which various compounds are added as third components to chlorinated steel and potassium chloride. A catalyst in which a rare earth compound is added as the third component has the advantage of being able to operate at a reaction temperature of 350 to 370°C (Japanese Patent Publication No. 3 B-20358). However, the biggest problem with the above-mentioned catalyst is that the catalytic active component Cu-KCL-rare earth compound becomes a molten salt under various reaction conditions. Therefore, when using a catalyst, it is necessary to support the above-mentioned active ingredient on a suitable carrier. The oxidation reaction of hydrogen chloride is 14Kc
Since it is an exothermic reaction of a l/mo I, it is difficult to use a fixed bed reactor for guided operation, and it is essential to use a fluidized bed reactor.

When a catalyst having 100% of molten salt supported on a carrier is used in a fluidized bed reactor, the catalyst body flows at a high linear velocity, resulting in fragmentation of the catalyst body. When the catalyst body is damaged, the molten salt stored in the pores of the carrier overflows to the outside, causing solidification of the catalyst body. During long-term operation, this causes a decrease in the fluidity of the fluidized bed.
Furthermore, the catalyst layer will solidify, making the operation unstable.

Furthermore, another problem with the copper chloride catalyst is that the STY is extremely low. Described in Special Publication No. 38-20358 (
Treatment of hydrogen chloride! 11 is 41 each 160L HC
L/K (] catalyst, only 1-1r. Also, C
hCm, &1nd, (london) 1962 7
Pages 6 to 83 also describe the same culm rα.

However, since the throughput of hydrogen chloride is low, the size of the reactor becomes too large, and HC1-10, C1,
For example, a large amount of F-grade material that can withstand l:f4 temperatures is used, which has the disadvantage of increasing reactor stress.

<Problems to be Solved by the Invention> The first object of the present invention is to improve the shortcomings that occur when using a copper chloride-based catalyst in a fluidized bed reactor, and to improve the STY from hydrogen chloride to chlorine. The purpose is to provide a method for manufacturing.

<Means for Solving the Problems of the Present Invention> The present invention provides a catalyst in which chlorinated steel or oxidized copper oxide, an alkali metal halide, a rare earth halide, or a compound thereof is supported on a carrier. When using the JJN reactor to oxidize hydrogen chloride with molecular oxygen to produce chlorine, the molar ratio of molecular oxygen to hydrogen chloride, HCL, is 10°.
This is a method for producing chlorine from hydrogen chloride in which the reaction is carried out in a range of 5 to 1/2.

In order to achieve the above object of the invention, the present inventors have made extensive research and found that the molar ratio of hydrogen chloride to molecular oxygen) ICL1
It has been found that when the reaction is carried out under conditions where 0□ is smaller than 110.5, caking of the catalyst particles does not substantially occur and the fluidized bed reactor can be stably operated for a long period of time. On the other hand, if a fluidized bed reactor is operated under conditions where HCL/O is greater than 4, catalyst particles will solidify.
It has been found that operating a fluidized bed is extremely difficult.

As mentioned above, the molar ratio of hydrogen chloride/M element is 110.5.
By keeping the value to a smaller value, the throughput of hydrogen chloride can be greatly improved and STY can be improved at the same time.

If HCL/O, is smaller than 1/2, this is preferable for preventing caking of the fluidized bed catalyst, but the amount of unreacted oxygen recycled increases, and the power cost required for this increases too much. This is undesirable.

In addition, when the generated chlorine is compressed and cooled to recover chlorine as a liquid, the chlorine recovery rate also decreases.
It is not appropriate to make , smaller than 1/2.

As the catalyst used in the present invention, a conventional catalyst in which a copper chloride-potassium chloride-rare earth compound is supported on silica is used.

The temperature of the reaction is in the range of 350-400 °C, HCL &
It is essential that the molar ratio of O is maintained within the above range.

HCL (7) Processing fdjt400~100ONL/K
The range of O0Hr is fully possible, and the conventional 100 to 20
BSTY is much more impressive than ONL/Ko and Hr.

To keep HCL/O, below 110.5,
Molecular lI! It is preferable to use pure oxygen gas as the elementary source.The purity of the M elementary gas is preferably 80% or more.If air is used as the hexagonal oxygen source, the above H
In order to maintain the CL10 ratio within the specified range, the nitrogen component becomes excessive, which is undesirable. That is, if the nitrogen content is large, it becomes difficult to maintain the linear velocity of the fluidized bed within an appropriate range, and the efficiency of the process of compressing and liquefying the produced chlorine decreases. In addition, the amount of inert ingredients increases, which is not preferable.

<Function> Specify the molar ratio of hydrogen chloride and molecular M element to prevent caking of the catalyst in the fluidized bed reactor.

<Example> The present invention will be explained using examples and comparative examples, and the results will be presented in the first section.
Shown in the table.

Surface M250m/c+, pore volume 0.9 (II/g silica gel is used for 10 bodies. The average particle size of the wood carrier is 62μ
It has a grain distribution suitable for 8-layer flow. Copper chloride 20wt
%, 10 wt % of potassium chloride, and 10 wt % of lanthanum chloride were infiltrated from an aqueous solution and then dried at 200°C to prepare a catalyst.

The packing density of this catalyst was 1.0 g/cc.

2KQ of this catalyst was packed into a stainless steel fluidized bed reactor with an inner diameter of 4 inches, and heated to 300'C in a sand fluidized bath from the outside.
heated to. Under the conditions of HCLlo, -110,75, H
CL processing ff180ONL/KO.

The response is +-+r. The temperature of the catalyst layer rose to 360-370°C due to the heat of reaction. The gas at the outlet was sampled, the chlorine formed as 1 was absorbed into a solution of 1, and the 1 formed was titrated with thioMM soda to measure the conversion rate of hydrogen chloride to chlorine. In order to test the durability of the catalyst, the reaction was continued for a long period of time, and the stability of the fluidized bed and the solidification of catalyst particles were checked by periodically sampling a small diameter of the catalyst from the fluctuations in the pressure difference in the fluidized bed.

For comparison, HCL/0. The results of continuous tests conducted with different ratios are also listed in Table 1.

Table-1 Comparative Example Example 1 Example 2 1-I OL/0 (mole ratio) 110.24+ 110.5
1/1700 hourly differential pressure change vJtfi small minute minute catalyst solidification
tfiffl None Intense HCL vagueness%
67 78 8314GG Hourly contact differential pressure fluctuation Medium f1 degree Micro Small amount of catalyst consolidation Small amount None Intense 80111 degrees%
62 75 Differential pressure fluctuation after 80210011 question Large Micro Small catalyst solidification
(moderately small, silently poor flowability) HCL concentration% 57 74 80 Example 3 Silica microspheres (average particle size 62 μ) with surface area 280 m/g and pore volume M0.85 cc/Q were coated with 12 wt% copper chloride and potassium chloride. The reaction was carried out in the same reactor as in Example 1 using a fluidized bed catalyst supporting 8 wt% and 12 wt% of didymium chloride (a mixture of rare earth chlorides consisting of 75% neodymium, 23% praseodymium, and 42% other rare earth w). Ta.

HCLlot-110,75, catalyst bed temperature 365”C
The reaction was carried out at a supply amount of 5HCL of 80 ONL/KO, Hr.

As a result of continuously carrying out the reaction for a long period of time, the reaction started at 72O.
HCL conversion rate 85% after Hrs, 82% after 2100Hrs
%, a conversion of 81% was maintained after 280 OHrs. The differential pressure fluctuation in the fluidized bed is minute, and immediately after the start of the reaction and at 2800 m
No change was observed after hours, and the operating condition of the fluidized bed was extremely stable.

<Effects of the Invention> It has been confirmed that the object of the invention is achieved by the present invention.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1) When producing chlorine by oxidizing an aqueous chloride system with molecular oxygen using a catalyst in which copper chloride or copper oxide and an alkali metal halide, a rare earth halide, or a compound thereof are supported on a carrier in a fluidized bed reaction. , the molar ratio of molecular oxygen to hydrogen chloride HCL/O_2 is 1/0.5 ~
A method for producing chlorine from hydrogen chloride, characterized in that the reaction is carried out in a range of 1/2.