JPS6039045B2 - How to dry dichlorobutene - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for drying dichlorobutene.

When dichlorobutene is mixed with water, various problems occur. For example, when 1,4-dichlorobutene-2 is isomerized to 3,4-dichlorobutene-1, which is the raw material for chloroprene, if water is contained, the isomerization reaction proceeds slowly and the reaction rate becomes slow. The mixture in the reactor solidifies. Furthermore, when dichlorobutene containing water is distilled, the distillation column and condenser may be corroded. Compounds such as iron chloride produced by corrosion are good catalysts for promoting the isomerization of dichlorobutene, and therefore cause other isomers to be mixed into dichlorobutene products that have been painstakingly produced. As a method for drying a mixture containing dichlorobutene,
There is dehydration due to calcium chloride.

However, when dehydrating with calcium chloride, 200 to 70 pm of water remains in the dried dichlorophthene, depending on the processing temperature. Since dichlorobutene containing 200 to 700 ppm of water is highly corrosive, it is necessary to use a high-quality acid-resistant material with a high content of nickel and added molybdenum, for example.

Examples of this acid-resistant high-grade material include SUS-316
and Hastelloy C (product name) are used. The purpose of the present invention is to prepare a mixture containing dichlorobutene with a residual water content of 50%.
It is an object of the present invention to provide a dehydration method capable of dehydrating down to ppm or less.

In the present invention, mordenite is used as a dehydrating agent for drying dichlorobutene or a mixture containing dichlorobutene.

The mordenite used in the present invention has the historical formula M20
:N203:XSi02:YH20 (where M is an alkali metal, alkali metal, hydrogen, or a mixture thereof, n is the valence of M, X is a number from about 6 to about 45, and Y It is a crystalline aluminosilicate having a number of about 1. Its typical composition is Ma20:Ma203:10 Si02:YH20.

Mordenite occurs naturally, but it can also be synthesized. The molar ratio of Si02:AI203 in mordenite is about 6 to 45:1, whereas it is 2 to 3:1 in A-type and ×-type zeolites and 3 to 6:1 in Y-type zeolite.
The content of Si02 is high. The crystal structure of mordenite is
a=18.13A, b=20.49A, c=7.52A
It is an orthorhombic system with a unit cell size of , and its pores are composed of 4-, 5-, 6-, 8-, and 12-membered rings of oxygen, and the maximum diameter of the 12-membered ring constituting the largest pore is approximately 7. .0A, the minimum length is an ellipse of about 5.8A. The pore paths formed by these pores are parallel to the C axis and have an independent tunnel structure.
It is different from three-dimensional cavities such as the type and Y-shaped faujasites. Therefore, the crystal structure of mordenite can be color-coded by X-ray diffraction analysis, and its content can be analyzed. The drying temperature is preferably 100°C or lower. 1000
Although it is possible to carry out the process at a temperature of 0 or more, it is not preferable because the amount of water per unit amount of dehydrating agent becomes small and frequent regeneration is required.

Example 1 S with an inner diameter of 25 ribs inserted into an electric furnace equipped with a temperature controller
A US-304 tube was used as a dryer, and 500 cc of mordenite having the composition of N Kame 20, AI 203, 1 Eiji 02, and YH 20 was filled into it.

A dichlorobutene mixture prepared to have a water content of about 1000 ppm (about 36% by weight of 3,4-dichlorobutene-1, about 50% by weight of 1,4-dichlorobutene-2, about 1% by weight of low-boiling compounds, and about 1% by weight of high-boiling compounds) (consisting of approximately 6% by weight) was fed to the dryer at a rate of 7000 ml per hour. After continuously supplying the dichlorophthene mixture for one hour, the supply of the dichlorophthene mixture was interrupted, the liquid was drawn out, the interior of the dryer was replaced with nitrogen gas, and the temperature was gradually raised while supplying the nitrogen gas at a rate of 100% per hour for regeneration.

It took 2 hours to raise the temperature to 25,000, and then another 2 hours to 25
After maintaining the temperature at 0.000, the temperature was lowered to 70.00 in about 1 hour.

Next, the supply of nitrogen gas was stopped, and a dichlorobutene mixture having the same composition as above was again supplied at a rate of 1/hour at 7000 ml. The above operation was repeated 10 times, and the moisture in the dichlorobutene mixture at the outlet of the dryer was measured using gas chromatography and a Karl Fischer moisture meter by collecting a portion of the liquid just before stopping the supply of raw materials for regeneration. It was measured using In both cases, the water concentration in the outlet liquid was in the range of 5 to loppm. On the other hand, after the test was repeated 10 times, the mordenite was taken out of the dryer and its performance and structure were checked. As a result, the amount of moisture adsorbed was almost the same as before use, and the crystal structure according to X-ray analysis was approximately 90%.
It was retained. For comparison, the above test was conducted using 3A-type zeolite Moleculite Snake and 4A-type zeolite Moleculiteze (both registered trademarks of Kurita Water Industries, Ltd.) as dehydrating agents.

Both were regenerated after feeding the dichloroptene mixture continuously for one hour to check performance and structure. As a result, both the amount of water adsorption and the X-ray intensity ratio were approximately 30% of those before use.
The moisture concentration in the dryer outlet liquid is 50 p
It was more than m. Furthermore, for comparison, a 10-circuit test was conducted using activated alumina as a dehydrating agent in the same manner as mordenite.

After 10 cycles, the amount of water adsorption decreased by about 50%, and the X-ray intensity ratio decreased by about 50%. The water concentration in the dryer outlet liquid gradually increases as the test is repeated, and in the 10th test it reaches 50%.
It has become more than pm. Example 2 A long-term test was carried out using the method of Example 1, varying the water concentration in the dichlorobutene mixture and the regeneration cycle.

In other words, Na20 at 500℃, mountain 203, 1 eave i02
- A dichlorophthene mixture (components are the same as in Example 1) containing about 500 ppm water based on YH20 was fed at a rate of 1 hourly. After continuous feeding at 70° C. for 4 holding periods, regeneration was carried out in exactly the same manner as described in Example 1, and the dichlorobutene mixture having the above-mentioned self-composition was fed again.

This operation was repeated 20 times. The moisture content after drying was measured each time and was in the range of 5-30 ppm throughout all tests. On the other hand, about 85% of the crystal structure of mordenite was maintained by X-ray analysis after the test was repeated 20 times. Example 3 The effect of water in dichlorobutene on striped hornworms was tested.

The water concentration in the dichloroptene mixture having the same composition as used in Example 1 was adjusted to two levels, 50 ppm and 500 ppm, and each solution was placed in a test tube, a metal piece was immersed in the test tube, and after the tube was sealed, the water concentration was 90 ppm. It was placed in an oil bath whose temperature was controlled at C. After two months, each test piece was taken out and the degree of corrosion was measured, and the results shown in Table 1 were obtained.

Table 1

Claims (1)

[Claims] 1 General formula M2/nO:Al_2O_3:XSiO
_2: YH_2O (where M is an alkali metal, alkaline earth metal, hydrogen, or a mixture thereof, n is the valence of M, X is a number from about 6 to about 45, and Y is about 12 or less A method for drying dichlorobutene characterized by using mordenite as a dehydrating agent.