JP2512637B2 - Method for producing allyl chloride - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing allyl chloride. More specifically, it relates to a method for producing allyl chloride from 1,2-dichloropropane by a dehydrochlorination reaction by catalytic decomposition.

[0002]

2. Description of the Related Art 1,2-Dichloropropane is a by-product when propylene is converted into chlorohydrin to produce a propylene oxide intermediate. It is also produced as a by-product in the production of allyl chloride by high temperature chlorination of propylene.
As an effective use of this by-product, 1,2-dichloropropane, it is known to produce allyl chloride by a dehydrochlorination reaction. The allyl chloride is useful as a raw material for resins such as epichlorohydrin, allyl alcohol, diallyl phthalate and other industrial chemicals.

Conventionally, the dehydrochlorination reaction of 1,2-dichloropropane is known to be a method of thermal decomposition or catalytic decomposition. In the thermal decomposition reaction, dehydrochlorination reaction is carried out at a high temperature of 500 to 700 ° C., and the selectivity for allyl chloride is 5.
It is 0 to 60%. Further, it is known that addition of a radical source such as chlorine or carbon tetrachloride improves the conversion rate and addition of oxygen improves the selectivity. In the catalytic cracking reaction, a dehydrochlorination reaction is carried out at a low temperature of 200 to 500 ° C. using a catalyst such as calcium chloride, silica-alumina and activated carbon.

[0004]

However, in the thermal decomposition reaction, when the conversion rate is increased, carbonaceous matter is generated, which causes problems such as a decrease in yield and clogging of the reaction tube. Further, in the catalytic decomposition reaction, 1-chloropropene and 2-chloropropene are the main products, and there is a problem that the selectivity of allyl chloride is low.

[0005]

[Means for Solving the Problems] The present inventors have conducted extensive studies to solve the above problems. As a result, in the dehydrochlorination reaction by the catalytic cracking described above, activated carbon heated in the presence of hydrogen chloride was used as a catalyst to give 1,2-
We have found that allyl chloride can be produced with high selectivity by dehydrochlorinating dichloropropane and completed the present invention.

That is, the present invention is a method for producing allyl chloride, which comprises heating 1,2-dichloropropane in the presence of activated carbon heat-treated in the presence of hydrogen chloride.

In the present invention, activated carbon heat-treated in the presence of hydrogen chloride is used as a catalyst for the dehydrochlorination reaction. The activated carbon is a carbonaceous raw material, activation method, pore size distribution,
The pore volume, specific surface area, etc. are not particularly limited, and known ones can be used without any limitation. Considering the space-time yield of allyl chloride, the pore volume is 0.3 cm ³
/ G or more and activated carbon having a specific surface area of 300 m ² / g or more is preferable. Further, the shape thereof is not particularly limited, but a crushed product or a molded product such as a spherical shape or a cylindrical shape is usually preferable because of easy handling.

Hydrogen chloride is used in the form of hydrogen chloride gas or an aqueous hydrochloric acid solution. Usually, commercially available activated carbon contains metals such as aluminum and iron as impurities, and therefore, it is washed with a mineral acid aqueous solution to remove them.
In the case of the present invention, it is preferable to use the above-mentioned hydrogen chloride in the form of an aqueous solution of hydrochloric acid because the impurities of the activated carbon can be washed at the same time. Even if the activated carbon is subjected to a heat treatment in the presence of an aqueous solution of a mineral acid other than hydrochloric acid, such as nitric acid or sulfuric acid, and the activated carbon obtained is subjected to the production of allyl chloride, allyl is obtained at a high selectivity as in the present invention. It is not possible to produce chloride.

In the present invention, the heat treatment of the activated carbon in the presence of hydrogen chloride is carried out by dipping the activated carbon in an aqueous hydrochloric acid solution, stirring and then drying, and further heating the liquid phase method, or by passing hydrogen chloride gas through the activated carbon. It is preferable to carry out the heating by a vapor phase method. Hereinafter, each will be described.

The concentration of the aqueous hydrochloric acid solution in the liquid phase method varies depending on the amount of activated carbon treated and the amount of the aqueous hydrochloric acid solution used, but it is usually in the range of 1 to 10 mol / l. The liquid temperature at the time of immersion is usually within the range of room temperature to 70 ° C, and the immersion time may be at least as long as the aqueous hydrochloric acid solution has entered the pores of the activated carbon, usually 1 to 10 hours. Within the range of. Next, the activated carbon pulled up from the hydrochloric acid aqueous solution
After the liquid adhering to the surface is dried, it is heated in an electric furnace or a reactor. The heating temperature is usually in the range of 300 to 700 ° C., and preferably set to a temperature 50 to 100 ° C. higher than the reaction temperature of the dehydrochlorination reaction of 1,2-dichloropropane described later. The heating time may be at least as long as the adsorbed hydrogen chloride gas, water vapor, decomposed gas and the like are completely desorbed, and is usually in the range of 1 to 20 hours. The atmosphere during heating may be air or an inert gas such as nitrogen or helium, and these gases are usually used by flowing them.

Next, the concentration of hydrogen chloride gas in the vapor phase method is not particularly limited and is usually 20 to 100.
Used within the range of volume%. Further, for diluting the hydrogen chloride gas, air or an inert gas such as nitrogen or helium can be used. The heating temperature is usually in the range of 300 to 700 ° C, preferably 50 to 100 ° C higher than the reaction temperature of the dehydrochlorination reaction of 1,2-dichloropropane. The heating time may be at least as long as the activated carbon and hydrogen chloride gas reach the adsorption equilibrium, and usually 1 to 1
Perform within 0 hours.

In the present invention, the dehydrochlorination reaction of 1,2-dichloropropane is carried out in the presence of activated carbon heat-treated in the presence of hydrogen chloride. The reaction temperature for the dehydrochlorination reaction is preferably 100 to 500 ° C, more preferably 200 to 500 ° C. Further, the pressure is preferably in the range of 0.5 to 10 atm, more preferably 0.5 to 5 atm.

The reaction system is not particularly limited and may be either a batch system or a continuous system, but industrially it is preferably a continuous system. When the present invention is carried out continuously, the space velocity SV (1,2-dichloropropane supply amount / activated carbon filling amount) is usually 100 to 500,000 hr.
^-1 done. The activated carbon may be used in either a fixed bed type or a fluidized bed type.

When this reaction is carried out using activated carbon which is not heat-treated in the presence of hydrogen chloride, 1-chloropropene, 2
-Increased production of chlorpropene and the like and reduced selectivity for allyl chloride. From this, it is considered that the heat treatment of the activated carbon in the present invention in the presence of hydrogen chloride contributes to the improvement of the selectivity of allyl chloride.

As can be understood from the above description, according to the present invention, allyl chloride can be produced at a higher conversion rate and a higher selectivity than 1,2-dichloropropane. In addition, carbonaceous substances are not generated and the reaction tube is not blocked. Further, 1,2-dichloropropane, which is a by-product, can be effectively used.

[0016]

EXAMPLES Examples will be given below to describe the present invention more specifically, but the present invention is not limited to these examples.

Example 1 20 g of granular activated carbon (plant-based) having a pore volume of 0.8 cm ³ / g and a specific surface area of 980 m ² / g
Was added to 500 ml of a hydrochloric acid aqueous solution having a concentration of 5 mol / l, and the mixture was stirred at room temperature for 6 hours.
It was dried at ° C. After drying the liquid adhering to the activated carbon surface, 5 g of activated carbon was put into a glass reaction tube (φ = 20 mm), and the reaction temperature of the dehydrochlorination reaction of 1,2-dichloropropane in Table 1 was carried out while circulating nitrogen gas. Heated at 100 ° C higher for 5 hours. Then, the temperature was lowered to the reaction temperature and the reaction was performed. The reaction was carried out by using a fixed bed atmospheric pressure distribution apparatus, and 30 ml of 1,2-dichloropropane was sent to a vaporizer at a rate of 0.5 ml / min by a micro quantitative pump, gasified and introduced into a reaction tube. The reaction temperature is 200 to 4
The temperature was changed in the range of 00 ° C. The reaction mixture was cooled with dry ice-methanol, collected, and analyzed by an FID gas chromatograph equipped with a PEG-20M capillary column. The conversion of 1,2-dichloropropane and the selectivity of allyl chloride were calculated by the following formulas. Unreacted PDC weight Conversion rate (%) = (1 ------------)-100 PDC supply weight (however, PDC represents 1,2-dichloropropane) Allyl chloride weight selection Rate (%) = ────────────── × 100 Product weight results are summarized in Table 1.

[0018]

[Table 1]

Comparative Example 1 A non-catalytic reaction was carried out without filling the reaction tube with activated carbon. The reaction procedure was the same as in Example 1. The results are shown in Table 2.
It was shown to.

[0020]

[Table 2]

Comparative Example 2 Instead of the aqueous hydrochloric acid solution used in Example 1, an aqueous nitric acid solution (concentration: about 5 mol / l) and an aqueous sulfuric acid solution (concentration: about 3 m)
ol / l) was used. All other operations are in Example 1.
Was performed in the same manner as described above. Also, for the reaction using activated carbon as it is, without performing treatment with a mineral acid aqueous solution,
I did. The respective results are summarized in Table 3.

[0022]

[Table 3]

Example 2 The activated carbon of Example 1 (plant type) was used, and the pore volume was 0.6 cm.
The crushed activated carbon (coal-based) having a specific surface area of ³ / g and a specific surface area of 850 m ² / g was replaced with hydrogen chloride treatment by a gas phase method. That is, 5 g of crushed activated carbon was charged into a reaction tube, hydrogen chloride gas diluted with nitrogen (30% by volume) was circulated, and the reaction temperature of the dehydrochlorination reaction of 1,2-dichloropropane in Table 4 was 100 ° C. Heat treatment was performed at a high temperature for 10 hours.
Then, the temperature was lowered to the reaction temperature and the reaction was performed. The reaction procedure was the same as in Example 1. The results are summarized in Table 4.

[0024]

[Table 4]

Claims (1)

(57) [Claims] 1. A process for producing allyl chloride, which comprises heating 1,2-dichloropropane in the presence of activated carbon heat- treated in the presence of hydrogen chloride.