JPS6319490B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing methyl chloride in the gas phase from methanol and hydrogen chloride. The reaction between methanol and hydrogen chloride in the gas phase is usually carried out at 250 to 350°C and about 0 to 4 kg/cm ² G. It is well known that commercially available alumina, silica/alumina, etc. are used as catalysts as they are. However, according to the experience of the present inventors, when these catalysts are used under the above conditions, they gradually deteriorate, leading to a decrease in the raw material conversion rate and an increase in side reactions. Although the cause of deterioration is not necessarily clear, one of the causes is thought to be the accumulation of carbon on the catalyst. As a result of various studies on prevention of catalyst deterioration over time, the present inventor found that the acid strength distribution state on the surface of alumina or silica/alumina (including the case of and, the same shall apply hereinafter) has a large influence. In particular, the presence of strong acid sites greatly contributes to the by-product of carbon. Therefore, by removing these strong acid sites, we have completed a catalyst that is less susceptible to deterioration due to use. That is, the present invention uses methanol and hydrogen chloride to produce methyl chloride as a catalyst with a surface acid strength of +0.8 to +15.0, preferably 4.0.
This is a method for producing methyl chloride characterized by using alumina of ~+12.2 or silica/alumina. One of the features of the present invention is its catalyst. The action of a catalyst in a chemical reaction is extremely subtle, and even a slight change in its surface state can produce unexpected effects. In the present invention, examples of using γ-alumina and silica-alumina have been known. However, in general, alumina is -3.0 to +3.3 silica, and alumina is -
8, and they were used casually in the past. In the case of such catalysts, when they are first used, they have sufficiently high activity and can be used for reactions, so it is presumed that little further study has been conducted. However, we investigated in detail the changes in catalyst performance through long-term operation, and
By specifying the distribution of surface acid sites within a certain range, and in particular by limiting the strong acid sites, it was possible to obtain a catalyst that hardly deteriorates even during continuous operation for 2 to 3 months. Such a catalyst can generally be easily obtained by treating commercially available alumina or silica-alumina with an alkali. As the alkali used in the alkali treatment, basic substances such as hydroxides or carbon salts of alkali metals or alkaline earth metals are used, but hydroxides are best. If desired, two or more of these may be used in combination. The alkali treatment method involves impregnating alumina or silica/alumina with a solution, preferably an aqueous solution, of an alkali metal or alkaline earth metal hydroxide dissolved in water or an organic solvent such as methanol, ethanol, acetone, etc. It is convenient to use after drying. Generally, it is most preferred to further condition the dry catalyst. Of course, as another manufacturing method, the above-mentioned alkali metal or alkaline earth metal hydroxide or the like may be added in advance when manufacturing alumina or silica-alumina. The temperature for calcining is preferably 110°C or higher, preferably 400°C or higher and 600°C or lower. In the present invention, the surface acid strength is expressed by a Hammett acidity function, and its measurement method is based on the Benetsi method. Conventionally known catalyst shapes, reaction methods, etc. used in the present invention can be applied as they are. For example, the catalyst can be pelletized into various shapes before or after the treatment of the present invention. The catalyst is used by filling it in a reactor and passing methanol vapor and hydrogen chloride through the reactor at an elevated temperature. The reaction conditions are not particularly limited, but the space-time velocity is 300 to 1000 h _v ^-1 ,
Generally, the temperature is 200 to 400°C and about 0 to 5 kg/cm ² G. According to the present invention, it is possible to obtain a catalyst with a long life, which could not be expected with conventional technology, in which the yield of methyl chloride is maintained at 90% or more in continuous operation for four months or more. Therefore, the present invention is an industrially extremely useful method for producing methyl chloride. Examples and comparative examples are shown below. Example 1 Spherical alumina with a diameter of about 5 mm and a surface acid strength of -
4.5 kg of 3.0 to +4.8 was immersed for 2 hours in a solution of 117 g of reagent grade sodium hydroxide dissolved in 3 pure water. After that, after drying at 110℃ for 20 hours,
It was baked at 450°C for 2 hours. The acid strength of this is +6.8 ~
It was +15.0. This catalyst has an inner diameter of 43 mm and a length of 1 m.
The reaction temperature was 300°C, methanol:HCl molar ratio was 1:1.1, and methanol was supplied at 1.5 kg/hour for reaction. After 3000 hours, a part of the catalyst was taken out and the amount of carbon was measured. The results are shown in Table-1. 20 ml of the taken out catalyst was placed in a reaction tube with an inner diameter of 30 mm, and the methanol:HCl molar ratio was 1:1.1, methanol was supplied at 12 g/hr, and the reaction was carried out at 300°C. The results are shown in Table-1. Comparative Example 1 shows the results of the catalyst that was not treated with alkali.
It is shown in Table-1. Example 2 Alumina 4.5Kg same as that used in Example 1
was immersed in a solution of 10 g of reagent-grade sodium hydroxide dissolved in 3 parts of pure water, filtered, and heated at 110℃ for 20 minutes.
After drying for an hour, it was fired at 450°C for 2 hours. The acid strength of this was +0.43 to +6.8. Table 1 shows the results of the same operation as in Example 1. Example 3 5kg of the same alumina used in Example 1 was immersed in a solution of 252g of reagent grade potassium hydroxide dissolved in 3.4% pure water for 2 hours, dried at 110℃ for 20 hours, and then dried at 450℃ for 2 hours. Fired. The acid strength of this is +
It was 6.8 to +15.0. Table 1 shows the results of the same operation as in Example 1. Example 4 5 kg of silica/alumina with a surface acid strength of -8 or less
Soak for 2 hours in a solution of 420g of reagent grade barium hydroxide dissolved in 3.2% pure water, filter, and then
It was dried at 110°C for 20 hours and then fired at 450°C for 2 hours. The acid strength of this was +6.8 to +15.0. Table 1 shows the results of the same operation as in Example 1. Comparative example 2 3.5 kg of the same alumina used in Example 1
Soak for 2 hours in a solution of 300g of reagent grade sodium hydroxide dissolved in 5 pure water, filter, and then
It was dried at 110°C for 20 hours and then fired at 450°C for 2 hours. The acid strength of this was +15 to +18.4. Grind a part of this to about 100 mesh, put 20 ml into a reaction tube with an inner diameter of 30 mm, methanol: HCl molar ratio 1:1.1,
Methanol was supplied at 12 g/hr and the reaction was carried out at 250°C. The results are shown in Table 1. Example 5 The same alumina as in Example 1 was treated with reagent special grade sodium hydroxide and heated to 105°C after filtering and washing.
After drying for 20 hours at 500℃, acid strength +4.0~+
A catalyst of 12.2 was obtained. This was subjected to a reaction between methanol and hydrogen chloride in the same manner as in Example 1. Display the results -
Shown in 1.

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Claims (1)

[Scope of Claims] 1. A methyl compound characterized in that alumina or silica-alumina having a surface acid strength of +0.8 to +15.0 is used as a catalyst in the reaction of producing methyl chloride from methanol and hydrogen chloride. Method for producing chloride. 2 By treating commercially available alumina or silica/alumina with alkali, its surface acid strength can be increased.
The method according to claim 1, characterized in that a catalyst adjusted to 0.8 to +15.0 is used. 3 Commercially available alumina or silica/alumina is soaked in an alkaline aqueous solution, dried, and heated to 400°C.
3. The method according to claim 2, which uses a catalyst characterized in that it is calcined at ~600°C.