JPS5943930B2 - Method for producing methyl chloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing methyl chloride from hydrogen chloride and methyl alcohol.

Many methods for producing methyl chloride from hydrogen chloride and methyl alcohol have been reported, but the typical method currently being industrialized is a gas phase catalyst in which the reaction is carried out in one gas phase using a catalyst such as alumina. method, a liquid phase catalytic method in which a reaction is carried out using a catalyst such as zinc chloride in two liquid phases,
and a liquid phase non-catalyst method in which the reaction is carried out in three liquid phases without the presence of a catalyst. However, each of these conventional methods has various disadvantages and cannot be said to be necessarily satisfactory.

For example, in the gas phase catalytic method, the reaction temperature is as high as 300 to 500° C., so the by-product of dimethyl ether is larger than in other methods, and the catalyst needs to be replaced or regenerated due to catalyst deterioration.

In addition, in the liquid phase catalytic method, the reaction temperature is higher than in the liquid phase non-catalytic method, and since a catalyst is used, dimethyl ether is more likely to be produced as a by-product, and it is necessary to remove water accompanying the raw material hydrogen chloride and water generated during the reaction by evaporation. Because of this, the amount of heating may be large, and because the reaction rate is slow and the reaction rate is low, unreacted hydrogen chloride and methanol evaporate, which requires equipment for recovering them.

Furthermore, in the liquid phase non-catalytic method, the by-product of dimethyl ether is smaller than in the former two methods, but the reaction rate is very low, so an excessive reaction volume is required, and the J reaction rate is low, so unreacted hydrogen chloride and There were drawbacks such as the need for methyl alcohol recovery equipment.

Many examples are known of the same liquid phase non-catalytic method as the present invention. For example, in JP-A No. 53-34704, a similar reaction was carried out in an excess of hydrogen chloride.
Since the by-product water is extracted in liquid form, unreacted hydrogen chloride accompanies the by-product water, resulting in a low reaction rate of hydrogen chloride, and a large amount of refining energy is required to reuse the by-product hydrochloric acid. There are disadvantages such as the need for

The greatest feature of the method of the present invention is that in producing methyl chloride in a liquid phase without catalyst, compared to the conventional technology, (1) the production rate per unit volume of the reactor (hereinafter referred to as the "volume hourly yield") is higher. (2) almost stoichiometrically converts hydrogen chloride introduced as a raw material into methyl chloride; and (3) almost eliminates hydrogen chloride taken out of the reactor as an unreacted product. , (4) Furthermore, a production method that dramatically simplifies the equipment for recovering unreacted substances such as unreacted methyl alcohol by removing the water produced by the reaction from the reactor together with methyl chloride as water containing almost no hydrogen chloride. The purpose is to provide the following.

That is, the present invention relates to a method for producing methyl chloride, which is characterized by introducing hydrogen chloride and methyl alcohol into a reaction solution containing water, methyl alcohol, and hydrogen chloride at a temperature of 70 to 150°C, and causing the reaction to occur. .

By the way, the production rate of methyl chloride is as follows when the reaction medium is a solution consisting of hydrogen chloride, water and methyl alcohol.
It is known that increasing the temperature, hydrogen chloride concentration, and methyl alcohol concentration of the solution will increase the concentration. The yield of methyl chloride is reduced accordingly as the scattering of hydrogen and methyl alcohol vapors increases.

Furthermore, as the methyl alcohol concentration increases, the by-product of dimethyl ether increases. However, when the present inventors used a substantially catalyst-free reaction solution consisting of water, methyl alcohol, and hydrogen chloride as a reaction medium, and introduced hydrogen chloride gas and methyl alcohol into the reaction medium, Surprisingly, it is possible to recover methyl chloride from the scattering of hydrogen chloride and methyl alcohol without the need to raise the temperature of the above-mentioned "reaction solution" so high and without increasing the hydrogen chloride and methyl alcohol concentrations. It was confirmed that the production rate of methyl chloride was significantly increased without any decrease in production rate or increase in by-product of dimethyl ether.

The reason for this remarkable effect is thought to be as follows.

In other words, when hydrogen chloride gas and methyl alcohol are introduced into the reaction solution, they become bubbles and rise in the reaction solution, passing through the gas-liquid interface and dissolving into the reaction solution. In the vicinity, the temperature, hydrogen chloride concentration and methyl alcohol concentration are related to the temperature of the reaction solution,
Higher than hydrogen chloride and methyl alcohol concentrations. The production rate of methyl chloride in liquid phase reaction depends on temperature,
Since the hydrogen chloride and methyl alcohol concentrations increase significantly with small increases, the rate of methyl chloride formation at and near the gas-liquid interface is significantly higher than that in other parts of the reaction solution, resulting in an overall increase in methyl chloride concentration. It is thought that the production rate of methyl chloride increases. Bubbles introduced in gaseous form and rising through the reaction solution reduce the reaction components, hydrogen chloride and methyl alcohol, and therefore reduce the temperature, hydrogen chloride concentration, and methyl alcohol at and near the gas-liquid interface. The alcohol concentration gradually approaches the temperature and concentration of the reaction solution and eventually becomes almost the same, so the amount of hydrogen chloride and methyl alcohol that is entrained in the generated methyl chloride and scattered does not increase, and the yield of methyl chloride is Can hold high values.

The fact that the production rate of methyl chloride can be significantly increased compared to the production rate by homogeneous liquid phase reaction alone in the reaction solution without substantially increasing the temperature, hydrogen chloride concentration, and methyl alcohol concentration of the reaction solution. This is an extremely important advantage because it does not involve any loss of hydrogen chloride or methyl alcohol and no increase in dimethyl ether by-product (these can be kept low). In general, the physical absorption rate and dissolution rate of hydrogen chloride gas and methyl alcohol are extremely high compared to the reaction rate, so the volume at and near the interface is extremely small and is considered to have no effect on improving the overall reaction rate. It is surprising that the effect of significantly improving the overall reaction rate as described above can be obtained despite the above-mentioned effects.

As explained above, the present invention essentially involves forming a gas-liquid rising surface in the reaction solution by introducing hydrogen chloride gas and methyl alcohol into the reaction solution, thereby increasing the concentration of hydrogen chloride and methyl alcohol. This can be achieved by effectively utilizing reactions at or near these interfaces, where the alcohol concentration and temperature are high and the production rate of methyl chloride is extremely high. In order to more effectively achieve the effects of the present invention, it is necessary to maintain the hydrogen chloride concentration in the reaction solution at 25% by weight or less. If this concentration exceeds 25% by weight, the amount of hydrogen chloride lost to the produced methyl chloride and water increases, resulting in a decrease in the yield of methyl chloride. Note that hydrogen chloride monowater and hydrogen chloride monowater monomethyl alcohol systems have a maximum azeotropic point, so it is extremely difficult to recover the lost hydrogen chloride.
The yield of methyl chloride is forced to decrease. The reaction temperature is 7
A temperature of 0 to 150°C (reaction solution temperature) is required.

This is because at temperatures below 70°C, the production rate of methyl chloride decreases, while at temperatures above 150°C, unfavorable results such as an increase in the by-product of dimethyl ether are brought about. Note that there is no need to set particularly strict restrictions on the methyl alcohol concentration in the reaction solution.

The key is to maintain the hydrogen chloride concentration below 25% by weight and keep the temperature at 7%.
The methyl alcohol concentration may be such that it can be maintained at 0 to 150°C, and may be approximately 0.5 to 40% by weight. If this is 0.5% by weight or less, 25% by weight of hydrogen chloride
If it exceeds 40% by weight, it becomes difficult to maintain the reaction temperature at 70 to 150°C. From the viewpoint of keeping the amount of dimethyl ether by-product as low as possible, it is desirable to keep the methyl alcohol concentration as low as possible within the above range. The reaction pressure is the temperature of the reaction solution at 70-1
Any pressure can be used as long as the temperature can be maintained at 50° C. and the hydrogen chloride concentration can be maintained at 25% by weight or less, but a pressurized state is preferable in order to further improve the reaction results.

When hydrogen chloride gas is introduced into the reaction solution, it is desirable to keep the reaction solution in a static state. When introduced into a reaction solution that is vigorously flowing due to mechanical stirring or the like, the rate of absorption of hydrogen chloride gas into the reaction solution increases, so the hydrogen chloride concentration becomes high relative to the size of the space-time yield. In addition, the introduction rate of hydrogen chloride gas into the reaction solution is per 11 of the reaction solution,
It is desirable to set the rate to 1007 per hour or more, and if the introduction rate is lower than this, not only will the space-time yield decrease, but also the proportion of hydrogen chloride gas absorbed into the reaction solution will increase, and the proportion of the size of the space-time yield will increase. In this case, the hydrogen chloride concentration in the reaction solution does not decrease. The molar ratio of hydrogen chloride and methyl alcohol supplied to the reaction solution does not need to be strictly defined, and the molar ratio of methyl alcohol (MeOH) to hydrogen chloride (HCl) (MeOH)/(HCl) is approximately 0.5. ~3.
It is sufficient if the value is within the range of 0.

If this becomes 0.5 or less, it becomes difficult to maintain the hydrogen chloride concentration in the reaction solution at 25% by weight or less,
On the other hand, if it exceeds 3.0, the methyl alcohol concentration increases and it becomes difficult to maintain the temperature of the reaction solution at 70 to 150°C. Stoichiometrically, it is desirable to set this molar ratio to 1.0, but even if methyl alcohol is in excess of 1.0 or more, the excess methyl alcohol will be converted into methyl chloride together with the water produced by the methyl chloride production reaction. After being taken out of the reaction system, the methyl alcohol may be separated and supplied to the reaction system again. When hydrogen chloride and methyl alcohol are each introduced into the reaction solution in gaseous form, the reaction system becomes exothermic and it is necessary to cool the reaction solution.

On the other hand, when methyl alcohol is introduced in liquid form, the reaction system becomes endothermic and the reaction solution needs to be heated. It is possible to balance exothermic and endothermic reactions, thereby saving energy for reaction control. Next, steps for carrying out the method of the present invention will be explained based on the attached drawings.

First, the drawings schematically illustrate steps for carrying out the method of the present invention.

In the figure, 1 is a reactor, which holds the above-mentioned reaction solution.

This reactor may be either a tank type or a tower type. Hydrogen chloride and methyl alcohol are introduced into the bottom of the reactor 1 and reacted. Hydrogen chloride is carried out in a gaseous state, and methyl alcohol is carried out in a gaseous and/or liquid state. The drawing shows the case where the gas is introduced, and 2 is an evaporator for methyl alcohol. Furthermore, if there is a partition plate to separate the reaction solution held in the reactor 1 into upper and lower parts, the concentration of hydrogen chloride and methyl alcohol can be made higher in the lower part and lower in the upper part, which results in better results. can be given.

Further, a constant amount of the reaction solution is always circulated from the upper part of the reactor into the tank 3 by a pump 4 in order to eliminate temporal variations and changes in the amount of actual liquid in the reactor due to gas inclusion. However, the circulation should not be too vigorous for the reasons mentioned above. By reacting in this manner, methyl chloride is produced, which is introduced in gaseous form from the upper part of the reactor 1 through the reflux condenser 5 and into the recovery condenser 6.

In the reflux condenser 5, part of the entrained water and methyl alcohol is refluxed, but an amount of water corresponding to the water by-produced by the reaction is led together with the methyl alcohol to the recovery condenser 6, where it is condensed and converted into water. Enter receiver 7. On the other hand, uncondensed methyl chloride is led to a cryogenic condenser 8, where it is condensed and stored in a methyl chloride receiver 9. Note that methyl alcohol is separated from the water-methyl alcohol in the water receiver 7 by distillation or the like, and water containing almost no hydrogen chloride is discharged.

The advantages of the present invention are summarized below.

(1) The present invention is a method that does not use a catalyst, and can completely avoid the economic disadvantage of using a large amount of catalyst and the disadvantage of contamination with the product as in the prior art.

(2) The space-time yield can be significantly increased, and the economic and industrial advantages are extremely large.

The space-time yield greatly influences the economic efficiency of reaction equipment, and according to the method of the present invention, the space-time yield of methyl chloride can be reduced to 20%.
It can also be made 0 to 400 kg/m3hr. (3
) The reaction yield of hydrogen chloride and methyl alcohol can be significantly improved.

Even if the hydrogen chloride concentration in the reaction solution is lowered to 25% by weight or less, a sufficiently economical space-time yield can be obtained, and as a result, the water distilled out with the generated methyl chloride contains hydrogen chloride. Hydrogen chloride is contained in reactor 1.
Almost 100% methyl chloride can be utilized in one pass. When this utilization rate is low, hydrogen chloride is lost along with the water produced, but separating and recovering this hydrogen chloride from water requires a complicated azeotropic distillation system and a large amount of energy.

Example 1 An overflow pipe was installed at the top of a Pyrex glass column with an internal volume of 2000 ml and an internal diameter of 50 mm, and the length was 1600 m.
A reactor capable of holding a liquid of
A reaction solution consisting of water, methyl alcohol and hydrogen chloride was charged into a ml tank and heated.

The pressure in the reaction system was maintained at 1.5k9/cdG, and when the temperature of the reaction solution reached 100°C, hydrogen chloride gas and methyl were pumped and circulated from the tank to the reactor through the nozzle at the bottom of the reactor. Alcohol supply was started at the same time.

The hydrogen chloride feed rate was adjusted to 2737/hour. Methyl alcohol was introduced into the evaporator in gas form using a metering pump, and the feed rate was adjusted to 3347/hour. As the reaction progresses, methyl chloride, water and a small amount of dimethyl ether are produced.

The produced methyl chloride is taken out in the gas phase from the top of the reactor and led to a recovery condenser via a reflux condenser. This methyl chloride is accompanied by water, methyl alcohol, and hydrogen chloride, but due to the action of the reflux condenser, when some of these are refluxed, most of the hydrogen chloride is refluxed, so it is not transferred to the next step. The water produced by the reaction with methyl chloride and the accompanying methyl alcohol are led from this reflux condenser to the recovery condenser, where the condensed water and methyl alcohol are put into a water receiver, and the uncondensed methyl chloride is sent to a deep-cooled condenser. where it was condensed and stored in a methyl chloride receiver. Regarding the water, methyl alcohol, and some dissolved methyl chloride in the water receiver, the methyl chloride was vaporized and recovered by heating, and the methyl alcohol was separated and effectively used for the reaction. The temperature of the reaction solution when the reaction is in steady operation is 12
The temperature was 0°C, and the concentration of hydrogen chloride in the reaction solution was 16.5% by weight, and the concentration of methyl alcohol was 5% by weight.

The water receiver contains 13% water and 13% methyl alcohol each.
67/hour, 93? /hour, and contained almost no hydrogen chloride. On the other hand, methyl chloride was obtained at a rate of 3797/hour, which included dimethyl ether at a rate of 3797/hour. It contained 5% by weight.

The actual consumption of methyl alcohol is 242 k/hour, the reaction rate of hydrogen chloride to methyl chloride is 99.9%, and the reaction rate of methyl alcohol to methyl chloride is 71.5% (however, the accompanying methyl alcohol is (99.0% considering that it was recovered and reused), and the space-time yield of methyl chloride was 237 kg/Rrl'Hr. Example 2 According to the method of Example 1, hydrogen chloride and methyl alcohol were reacted.

However, water, methyl alcohol, and hydrogen chloride accompanying methyl chloride generated from the upper part of the reaction solution are all condensed in a reflux condenser and refluxed into the reactor, and the supply rate of hydrogen chloride monomethyl alcohol is 280 k/hour and 242 k/hour, respectively. ku/time. When the reaction was carried out in this manner, by-product water was accumulated in the reactor, so a portion of the reaction solution was extracted from the bottom of the tank.

Reaction temperature at steady state: 110°C, hydrogen chloride concentration: 1
8% by weight, methyl alcohol concentration 9.1% by weight,
As a result, methyl chloride was obtained at a rate of 3507/hr, which contained 1.6% by weight of dimethyl ether.
The water produced as a by-product of the reaction was discharged from the system by withdrawing the reaction solution from the bottom of the tank at a rate of 1727/hour.
Since the reaction solution contained hydrogen chloride and methyl alcohol at the above concentrations, these were discharged at the same time.

The reaction rate of hydrogen chloride to methyl chloride was 90.0%, the reaction rate of methyl alcohol was 90.0%, and the space-time yield of methyl chloride was 219 kg/M3hr.

Example 3 According to the method of Example 1, hydrogen chloride and methyl alcohol were reacted.

However, a mixture of water, methyl alcohol, hydrogen chloride, and some methyl chloride in a water receiver with an inner diameter of 50 mm
s A distillation column having a height of 1000 mm and packed with 10 mm Ratschig rings is supplied, and methyl chloride, methyl alcohol and a small amount of water are extracted from the top of the column and returned to the reaction column.
On the other hand, the feeding rate of methyl alcohol is 242'? / Tokito.

As a result, methyl chloride was obtained at a rate of 3797/hour,
This contained 0.5% by weight of dimethyl ether.

The reaction rates of hydrogen chloride and methyl alcohol to methyl chloride were 99.9% and 99%, respectively, and the space-time yield of methyl chloride was 2371<g/M3hr.

Example 4 According to the method of Example 1, hydrogen chloride and methyl alcohol were reacted.

However, the supply rates of hydrogen chloride and methyl alcohol were 4707/hour and 3877/hour, respectively.

Temperature of reaction solution in steady state: 110°C, hydrogen chloride concentration: 21.4% by weight, methyl alcohol concentration: 7.5% by weight
It was hot.

As a result, methyl chloride was obtained at a rate of 571 k/hr, which contained 0.9% by weight of dimethyl ether.

The reaction rates of hydrogen chloride and methyl alcohol to methyl chloride were 87.0% and 92.3%, respectively, and the space-time yield of methyl chloride was 357k9/M3hr.

Example 5 Hydrogen chloride and methyl alcohol were reacted according to the method of Example 2.

However, the reaction pressure was atmospheric pressure, the reaction solution temperature was 88°C, and the supply rates of hydrogen chloride and methyl alcohol were each 27°C.
The reaction was carried out at 77/hour and 2357/hour, and the concentrations of hydrogen chloride and methyl alcohol in the reaction solution at steady state were 24.5% by weight and 17.0% by weight, respectively.

As a result, methyl chloride was obtained at a rate of 3187/hour,
This contained 0.3% by weight dimethyl ether. The reaction rates of hydrogen chloride and methyl alcohol to methyl chloride were 82.8% and 85.4%, respectively, and the space-time yield of methyl chloride was 199 kg/M3hl-.

[Brief explanation of drawings]

The drawings show a schematic process diagram for carrying out the method of the invention. 1... Reactor, 2... Evaporator, 3...
... Tank, 5 ... Reflux condenser 6
... Recovery condenser 7 ... Water receiver 1, 8 ... Deep cooling condenser 9 ...
...Methyl chloride receiver.

Claims (1)

[Claims] 1. Hydrogen chloride gas and methyl alcohol are introduced into a reaction solution consisting of water, methyl alcohol, and hydrogen chloride, and has a hydrogen chloride content of 25% by weight or less and a temperature of 70 to 150°C to cause a reaction. A method for producing methyl chloride, characterized by: 2. The method according to claim 1, wherein when hydrogen chloride gas is introduced into the reaction solution, the introduced hydrogen chloride gas exists as bubbles in the reaction solution. 3. The method according to claim 1 or 2, characterized in that hydrogen chloride gas is introduced at a rate of 100 g per hour or more per liter of reaction solution. 4 Methyl chloride production reaction at atmospheric pressure to 3 kg/cm^
The method according to claim 3, characterized in that the method is carried out in 2G. 5. Claim 4, characterized in that water produced as a by-product in the methyl chloride production reaction is extracted from the reaction solution in gaseous form.
The method described in section.