JPS5943932B2 - Manufacturing method of methyl chloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing methyl chloride by reacting ammonium chloride and methylamine.

Methyl chloride is an industrially important compound that is used as an intermediate raw material in the production of chloromethanes such as methylene chloride, chloroform, and carbon tetrachloride, as well as as an intermediate raw material in the production of silicone resins and as a solvent in the production of butyl rubber. be. Conventionally, methods for producing methyl chloride include thermal chlorination of methane with chlorine, photochlorination, or
One known method is a dehydration condensation reaction between methanol and hydrochloric acid.

On the other hand, a large amount of ammonium chloride is produced as a by-product in the production of soda carbonate using the ammonia-soda method, but production is forced to decline due to demand constraints when processing this as fertilizer.・It is hindering the rationalization of the soda law. For this reason, various methods have been proposed for recovering chlorine or hydrochloric acid and ammonia from ammonium chloride, but all of them involve complicated reactions and operations, and no satisfactory method has been found. The present inventor conducted extensive studies on an advantageous method for producing methyl chloride using ammonium chloride as a raw material, and as a result, discovered that methyl chloride can be obtained by reacting ammonium chloride with methylamines, and completed the present invention.

That is, the present invention is a method for producing methyl chloride by subjecting ammonium chloride and methylamines to a gas phase catalytic reaction in the presence of a solid catalyst.

In the present invention, as the ammonium chloride used as a raw material, a wide range of ammonium chloride can be used without particular limitation, such as naturally occurring ones, those obtained by the ammonia-soda method, double decomposition of ammonium sulfate and salt, etc.

Also, these ammonium chlorides mixed with methylamines, their hydrochlorides, or tetramethylammonium chloride can be used without any problem.
Furthermore, it can be used in a wide variety of forms, including solid forms, aqueous solutions, and slurry forms, and these are sublimed inside or outside the reactor. The composition ratio of methylamines used as one of the raw materials is not particularly limited, and trimethylamine, dimethylamine, and monomethylamine may be used alone or in a mixture of any ratio in gaseous or aqueous solution. It may also be mixed with methanol. The catalysts used in the present invention are solid catalysts, such as various oxides such as alumina, silica, titania, magnesia, chromia, silica-alumina, zeolite, aluminaboria, silica-magnesia, silica-zirconia, zinc monochromite, etc. , various composite oxides such as iron-chromia, titania arboria, activated carbon, and activated carbon supported with sodium aluminate potassium aluminate, or a mixture of two or more of these catalysts can be used. may contain hydrochlorides, sulfates, phosphates, aluminates, molybdates, nitrates, etc. of various metals.

Further, there is no particular restriction on the shape of these catalysts, and the contact between the raw material gas and the catalyst can be carried out in any suitable manner, such as a fixed bed or a fluidized bed. The supply ratio of raw material ammonium chloride and methylamines can be arbitrarily selected, but the molar ratio of ammonium chloride to the total number of moles of methyl groups in methylamines is 0.1 to 5.0, preferably 0.2 to 5.0.
It is in the range of 1.5.

As this value increases, the amount of unreacted ammonium chloride increases, requiring a large amount of energy to recover and recycle it. On the other hand, as the molar ratio decreases, unreacted methylamines increase and methyl Side reactions such as decomposition of amines and high boiling temperatures become more likely to occur. The reaction temperature in carrying out the present invention is in the range of 250 to 600°C,
Preferably it is in the range of 380 to 450°C.

At temperatures below 250° C., a substantial reaction rate cannot be obtained and the vapor pressure of ammonium chloride is low, resulting in a decrease in the ammonium chloride concentration in the raw material gas.

Further, at a temperature of 600° C. or higher, decomposition reactions increase and the methyl chloride selectivity decreases. The reaction pressure is not particularly limited and may be normal pressure, increased pressure or reduced pressure, but it is usually convenient to operate at normal pressure or slightly increased pressure.

The feeding space velocity (SV) of the raw materials to the reactor can vary within a fairly wide range, but is usually in the range of 100 to 3000 hrH, preferably 200 to 2000 hr.

According to the present invention, a mixture of ammonium chloride, methyl chloride, ammonia and methylamines is obtained as a reaction product. Ammonium chloride can be easily separated.

Unreacted ammonium chloride can be recycled and reused as a reaction raw material. Methyl chloride, ammonia and methylamines separated from unreacted ammonium chloride are further separated into methyl chloride, ammonia and methylamines by a known method such as a water absorption method. Ammonia and methylamines may be further separated by means such as distillation, and the methylamines may be used again as a reaction raw material, or the mixture may be recycled to the reaction system or purification system of the methylamine plant as necessary. . When the present invention has an adjacent methylamine plant, it is possible not only to effectively utilize the methylamines circulating in large quantities within the methylamine plant, but also to reduce the total number of methyl amines produced by the present invention. The reduced methylamines and ammonia can be reused as raw materials in the methylamine process,
Alternatively, since it can be sent to a purification system, it is possible to produce essentially only methyl chloride, in the same way as methyl chloride is produced by reacting methanol and hydrogen chloride, and moreover, it can be produced from cheap ammonium chloride. This is particularly advantageous because chlorine can be used effectively and ammonia can be recovered.

Furthermore, in the present invention, it can be advantageously used even when ammonium chloride is mixed with hydrogen chloride, aqueous hydrochloric acid, or even methylamine hydrochloride, so it is even more economical if these can be used as by-products. can be increased.

Example 1 A reactor with an inner diameter of 22 mmφ heated in an electric furnace was filled with 40 ml of MSr-alumina fluidized catalyst with an average particle size of 50 Itm (micrometers), and a mixed gas of trimethylamine and ammonium chloride was added to the reactor with a molar ratio of ammonium chloride to trimethylamine. Set the ratio to 1.0. SV560hr'-
1. Contact was carried out at a reaction temperature of 400°C.

The high-temperature reaction product gas is introduced into a cylindrical glass air-cooled collector equipped with a filter, where it is gradually cooled to about 150°C to collect the entire amount of unreacted ammonium chloride as a solid.Then, it is converted into methylamine by water absorption. and ammonia were separated and collected from the methyl chloride-containing gas.

As a result, the conversion rate of ammonium chloride was 66.7%, the conversion rate of trimethylamine was 43.1%, the yield of methyl chloride was 66.6% based on ammonium chloride, the yield of methyl chloride was 22.2% based on the methyl group of trimethylamine, Dimethylamine yield: 14.1%, monomethylamine yield: 5.7%, ammonia yield based on the number of moles of trimethylamine supplied: 30
．． It was 0%.

Example 2 A fluidized catalyst prepared by adding Y-type zeolite to silica-alumina (Si/Al: 20,4) with an average particle size of 60 μm at an amount of about 5 wt% was packed into a fluidized reactor, and the moles of monomethylamine, ammonium chloride, and ammonia were Ratio 5' is 1:0.29:0
．． 78 raw material gas, reaction temperature 352℃, SV5OOh
A fluid contact reaction was carried out under conditions of r-1.

As a result of recovering the reaction product using the same method as in Example 1, the conversion rate of ammonium chloride was 53.0%, the conversion rate of monomethylamine was 69.2%, and the yield of methyl chloride based on ammonium monochloride was 52.5%. , the yield of methyl chloride based on the methyl group of monomethylamine supplied was 15.1%, and the yield of trimethylamine and dimethylamine based on the same basis was 2%, respectively.
They were 7.4% and 24.1%. Further, the ammonia yield based on 1 mole of monomethylamine supplied was 61.5%. Example 3 In the presence of the same catalyst as in Example 2, raw material gas with a molar ratio of dimethylamine, ammonium chloride, and ammonia of 1:0.62:1 was reacted at a reaction temperature of 359°C and SV
The reaction and recovery were carried out in the same manner as in Example 1 except that the reaction was carried out under the conditions of 75 Ohr-1.

As a result, the conversion rate of ammonium chloride was 50.0%, the conversion rate of dimethylamine was 71.0%, the yield of methyl chloride was 50.0% based on ammonium chloride, and the yield of methyl chloride, trimethylamine, and monomethylamine was based on the methyl group of the supplied dimethylamine. The yields were 15.3%, 37.5% and 14.7%, respectively. Further, the ammonia yield based on the number of moles of dimethylamine supplied was 46.0%. Example 4 In the presence of the catalyst shown in Table 1, the molar ratio of trimethylamine, ammonium chloride, and ammonia was 1.0:0.88:
2.0 raw material gas at reaction temperature 350℃, SV6OOhr
Table 1 shows the results of reaction and recovery conducted in the same manner as in Example 1, except that the reaction was carried out under the conditions of -1.

Example 5 Activated carbon (4-.8 mesh) was used as a fixed bed catalyst and the molar ratio of dimethylamine to ammonium chloride was 1:1.
638 raw material gas, reaction temperature 380°C, SVlOOOO
The reaction and recovery were carried out in the same manner as in Example 1 except that the reaction was carried out under hrH conditions.

As a result, the conversion rate of ammonium chloride was 46.1%, the conversion rate of dimethylamine was 91.6%, the yield of methyl chloride was 46.1% based on ammonium chloride, and the yield of methyl chloride, monomethylamine, and trimethylamine was based on the methyl group of the supplied dimethylamine. The yields were 31.8%, 10.1% and 2, respectively.
It was 9.3%.

Further, the ammonia yield based on the number of moles of dimethylamine supplied was 94.1%. Example 6 Spherical γ-alumina with a diameter of 2 to 4 was used as a fixed bed catalyst, and the molar ratio of trimethylamine didimethylamine dimonomethylamine dichloride ammonium diammonium was 0.6.
The reaction and recovery were carried out in the same manner as in Example 1, except that the raw material gas having a composition of 8:0, 42:0.46:1:2.1 was reacted at a reaction temperature of 400 ° C. and under the conditions of SV9OOhr-1. I did it.

Claims (1)

[Claims] 1. A method for producing methyl chloride, which comprises subjecting ammonium chloride and methylamines to a gas phase contact reaction in the presence of a solid catalyst.