JPH0345068B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing N-alkylmorpholine from N-alkyldiethanolamine. More specifically, the present invention relates to improvements in catalysts and reaction methods for producing N-alkylmorpholine in high yield by bringing N-alkyldiethanolamine into contact with a catalyst containing alumina as a main component in the gas phase to react. N-alkylmorpholine is widely used as a raw material for solvents, disinfectants, fiber finishing agents, and as catalysts for polyurethane foam foaming, and is an extremely useful substance industrially. Conventionally, N-alkyldiethanolamine to N
-The method for producing alkylmorpholine is as follows:
Several methods have been proposed. For example, N-
Hydrochloric acid is added to the alkyldiethanolamine raw material, and a dehydration cycloreaction reaction is carried out in the liquid phase under the acidity of hydrochloric acid.
- Process for producing alkylmorpholines (U.S. patent
3654271). This liquid phase method is based on N
- Although it is advantageous in that alkylmorpholine can be obtained in high yield, the reaction is carried out under strong acidity using a large amount of hydrochloric acid or sulfuric acid, and after the reaction, the hydrochloride or sulfate of the amine is neutralized with an alkali. Sum processing and N-
Since the alkylmorpholine is recovered, it has the following disadvantages. In other words, the reaction takes a long time to complete, a large amount of acid or alkali is consumed as a raw material, and the resulting by-product salts must be separated through complicated operations, and the separated by-product salts are organic substances. Since it contains , it causes pollution problems when it is disposed of, and furthermore, there are problems such as corrosion of equipment due to the use of strong acids in the reaction. In order to solve these problems of the liquid phase method, in recent years, a gas phase method has been trending, which does not involve by-product salts and allows easy separation and recovery of N-alkylmorpholine. For example, the method by Ishiguro et al. (Pharmacy Journal 1952,
74 P1162-1165), using silica-alumina with a silica content of 75-86% by weight as a catalyst, the raw material N-ethyldiethanolamine was reacted without dilution at a concentration of 100% at a reaction temperature of 400°C to form N- Ethylmorpholine was obtained with a yield of 40.5%. For example, according to US Pat. No. 2,597,260, N-ethyldiethanolamine was reacted without dilution at a concentration of 100% using alumina as a catalyst at a reaction temperature of 340°C to produce N-ethylmorpholine in a yield of 59.8%. It has gained. However, although these gas phase methods are inherently extremely advantageous in terms of reaction and separation operations, they are industrially disadvantageous due to the problem of low yields. As a result of intensive studies aimed at improving the shortcomings of the prior art, the present inventors discovered new knowledge regarding catalysts and reactions in the production of N-alkylmorpholines from N-alkyldiethanolamines using a gas phase method, and achieved high yields. The present invention has been completed by establishing an industrially extremely advantageous method for obtaining the same. That is, when alumina containing metal oxides was used as a catalyst to react N-alkyldiethanolamine as a raw material in the gas phase, the selectivity was improved, especially by lowering the raw material concentration. An unexpected finding was obtained:
The reason behind this new finding is not clear, but ordinary solid acid catalysts such as silica/alumina, zeolite, and silica have low selectivity regardless of the raw material concentration, whereas metal oxides have low selectivity regardless of the raw material concentration. It is presumed that when the raw material concentration of the alumina contained was within a limited range, an intermediate suitable for the production of N-alkylmorpholine was formed, and the selectivity was greatly improved. Therefore, an object of the present invention is to provide an industrially excellent method for producing N-alkylmorpholine in high yield using N-alkyldiethanolamine as a raw material based on these new findings. That is, the gist of the present invention is that the general formula (In formula [], R is a C ₁ to C ₂₀ alkyl group or
_C3 - _C8 cycloalkyl group) from N-alkyldiethanolamine represented by the general formula (In formula [], R has the same meaning as in formula []) When producing N-alkylmorpholine, titania, zirconia, phosphorus pentoxide, sulfur oxide, tungsten oxide, chromia,
The content of one or more metal oxides selected from the group consisting of zinc oxide, manganese oxide, and antimony oxide is 0.1 to 0.1 based on the weight of the total catalyst.
This is a method for producing N-alkylmorpholine, which is characterized by using 10% alumina as a catalyst and carrying out the reaction in the gas phase. The present invention will be explained in detail below. The raw material used in the present invention is N-alkyldiethanolamine represented by the formula [], where R is
A _C1 - _C20 alkyl group or a _C3 - _C8 cycloalkyl group, specifically N-methyldiethanolamine, N-ethyldiethanolamine, N-ethyldiethanolamine,
-Propyldiethanolamine, N-butyldiethanolamine, N-hexyldiethanolamine, N-octyldiethanolamine, N-decyldiethanolamine, N-dodecyldiethanolamine, N-cyclopentyldiethanolamine, N-cyclohexyldiethanolamine, N
-cycloheptyldiethanolamine, N-cyclooctyldiethanolamine, and the like. Preferably, it is a _C1-8 alkyl group, such as a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, or octyl group. Preferred examples include N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine, and N-butyldiethanolamine. These N-alkyl diethanolamines are easily obtained by adding 2 moles of ethylene oxide to 1 mole of alkylamine or cycloalkylamine. (R is an alkyl group or a cycloalkyl group) The catalyst used in the present invention is alumina containing a metal oxide, and the metal oxide specifically includes titania, zirconia, phosphorus pentoxide, sulfur oxide, Tungsten oxide, chromia, zinc oxide,
One or more types selected from manganese oxide and antimony oxide. The content of metal oxides is between 0.1 and 10%, preferably between 0.1 and 10%, based on the weight of the total catalyst. When the metal oxide content is less than 0.1%, it is too small to have any effect of addition, and no increase in selectivity is observed. On the other hand, if the metal oxide content exceeds 10%, the properties of the added metal oxide will be strongly manifested, the amount of by-products due to decomposition will increase, and the selectivity will decrease, which is industrially undesirable. This catalyst is prepared from an aluminum compound and one or more compounds selected from titanium, zirconium, phosphorus, sulfur, tungsten, molybdenum, chromium, zinc, manganese, or antimony compounds. Examples of aluminum compounds include hydroxides, halides, nitrates, sulfates, oxides, and organic complex salts.Specifically, aluminum hydroxide, aluminum chloride, aluminum nitrate, aluminum sulfate, sodium aluminate, and alumina. ,
Examples include colloidal alumina, aluminum, and isopropoxide. Compounds of titanium, zirconium, phosphorus, sulfur, tungsten, molybdenum, chromium, zinc, manganese or antimony include hydroxides, halides, nitrates, sulfates, oxides or organic carboxylates, etc. Includes titanium tetrachloride, titania, titanium sulfate, zirconium hydroxide, zirconium oxychloride, zirconia,
Zirconium nitrate, zirconium sulfate, orthophosphoric acid, pyrophosphoric acid, phosphorus trichloride, sulfuric acid, tungstic acid, tungsten oxide, tungsten chloride, ammonium molybdate, molybdenum oxide, chromium sulfate, chromium chloride, chromium hydroxide, chromium nitrate, chromia, Zinc acetate, zinc oxide, zinc chloride, zinc hydroxide, zinc nitrate, zinc sulfate, manganese acetate, manganese chloride, manganese hydroxide, manganese oxide, manganese nitrate, manganese sulfate, antimonic acid, antimony oxide, antimony chloride, antimony nitrate, etc. can be given. A mixture of two or more of these compounds can also be used. Various methods can be used to prepare the catalyst in the present invention as long as the alumina and metal oxide constituting the catalyst are thoroughly and intimately mixed with each other. For example, water-soluble salts of aluminum and metals (such as halides, nitrates, or sulfates) are dissolved in water, stirred thoroughly to mix uniformly, and then an alkali, such as aqueous ammonia or caustic, is added. Aluminum and metals are precipitated as water-insoluble compounds, separated, washed with water, and after drying,
A method of firing, finely powdering aluminum and insoluble salts of metals (such as hydroxides or oxides),
Insoluble salts of aluminum (e.g. hydroxides or oxides), which are mixed with each other wet or dry in a gel or sol state, dried and then fired.
Add a solution such as a soluble salt of a metal to impregnate it,
It may be prepared by a method of drying and then firing. Firing is performed above the reaction temperature, and the firing temperature is 400 ~
The temperature is 700°C, preferably 450°C to 650°C. The catalyst thus prepared can be used in the form of powder, granules, cylinders, spheres or tablets. When used after molding, various commonly used methods can be employed, such as the method of molding before heating and firing as described above, or the method of molding after heating and firing. The form of alumina in the catalyst obtained by calcination is
Any form of θ, κ, δ, η, γ, χ and β-alumina may be used, but preferably γ-alumina,
Or η-alumina or γ-alumina and η-
It is a mixture of alumina. The specific surface area of the catalyst is 50 m ² /g or more, preferably 100 to 500 m 2 /g.
m ² /g. In the method of heating the raw material represented by the formula [] to the reaction temperature and contacting it with the catalyst, the concentration range of N-alkyldiethanolamine in the raw material mixed gas is 1 to 50 mol%, preferably 1 to 30 mol%.
It is. If the concentration is less than 1 mol %, the yield will be high, but since a large amount of diluent is used, the amount of product obtained per unit volume of catalyst will be small, resulting in poor economic efficiency. On the other hand, if the concentration exceeds 50 mol%, by-products such as polymers will increase and the yield will drop sharply, which is industrially undesirable. The diluent for adjusting the concentration of N-alkyldiethanolamine may be any diluent that is inert to the raw materials and products and gaseous under the reaction conditions, such as inert gases, nitrogen, hydrogen, water vapor, etc. or ammonia, preferably nitrogen, water vapor or ammonia. These diluents are mixed with vaporized N-alkyldiethanolamine gas and fed to the reactor. At that time, two or more of these diluents may be used in combination at the same time. Furthermore, when using steam, an aqueous solution of N-alkyldiethanolamine and water may be vaporized in an evaporator and then supplied to the reactor. The feed rate can be varied within a wide range, but typically the contact time based on the catalyst filling volume of the feed gas may be between 0.01 and 50 seconds, preferably between 0.5 and 10 seconds.
Seconds. If the reaction temperature is too low, the conversion rate will be extremely low.
If the temperature is too high, decomposed products will increase, so the temperature is 200 to 400°C, preferably 250 to 300°C. The method of the present invention may be carried out in a conventional fixed bed, but it can also be carried out in a fluidized bed. The reaction is usually carried out under normal pressure, but may also be carried out under reduced pressure or increased pressure. The gas exiting the reactor is generally N-alkylmorpholine, unreacted N
-alkyldiethanolamine and the inert gas used. N,N'-dialkylpiperazine and N-alkylethanolamine are mainly produced as by-products, but these are in small amounts and can be easily separated from N-alkylmorpholine. N-alkylmorpholine can be efficiently isolated from the reaction mixture by known purification methods such as distillation and extraction, and highly pure N-alkylmorpholine can be obtained. According to the method of the present invention, the yield of N-alkylmorpholine can be dramatically improved, the number of by-products has been greatly reduced, and separation and purification has become easier. It has become possible to obtain good yield and reduce utility. Hereinafter, the present invention will be explained in more detail with reference to Examples, but it is not limited to these Examples. The definitions of conversion rate and selectivity in Examples are as follows. Conversion rate = Number of moles of N-alkyldiethanolamine reacted/Number of moles of N-alkyldiethanolamine supplied x 100 (%) Selectivity = Number of moles of N-alkylmorpholine produced/Number of moles of N-alkyldiethanolamine reacted x 100 (%) Yield = Number of moles of N-alkylmorpholine produced/Number of moles of N-alkyldiethanolamine supplied x 100 (%) Comparative Examples 1 to 3 A catalyst was placed in a quartz reaction tube with an inner diameter of 26 mm and a length of 600 mm. of
After filling the reaction tube with 20 ml and heating it in an electric furnace to 280°C in a nitrogen stream, the nitrogen was turned off and 5.95 g of N-ethyldiethanolamine per hour and 15.3 g of water per hour were added using metering pumps. was supplied to the reaction tube. This corresponds to a composition of 5.0% by volume of N-ethyldiethanolamine and 95.0% by volume of water. The silica-alumina catalyst has a silica content of 72% by weight (manufactured by Catalysts & Chemicals Co., Ltd., trade name: IS-28), and has a specific surface area of 349 m ² /g. In addition, the alumina catalyst is 100wt% γ-alumina (Mizusawa Chemical Co., Ltd.)
Co., Ltd., trade name: Neobeat C), and the specific surface area is 210 m ² /g. The results are shown in Table 1.

[Table] Example 1 250 g of aluminum sulfate/13 hydrate was dissolved in 5 water, and a 20% ammonia aqueous solution was added dropwise to the solution while stirring to adjust the pH to 6. The obtained precipitate was filtered, washed with water, dried at 120℃, and ground to 12 mesh or less.
After forming into a tablet with a diameter of 5 mm and a height of 5 mm,
It was baked at 450°C for 3 hours. The proportion of sulfuric acid in the catalyst obtained was 4.6% based on the weight of the total catalyst, and the specific surface area was 330 m ² /g. A quartz reaction tube with an inner diameter of 26 mm and a length of 600 mm was filled with 20 ml of catalyst, and the reaction tube was placed in an electric furnace and heated to a temperature of 280°C in a nitrogen stream, then the nitrogen was stopped and 5.95 g of N was added per hour. -Ethyldiethanolamine and 15.3 g of water per hour were each supplied to the reaction tube using metering pumps. This corresponds to a composition of 5.0% by volume of N-ethyldiethanolamine and 95.0% by volume of water. The results are shown below, and the yield of N-ethylmorpholine was 88.0%. N-ethyldiethanolamine conversion rate 99.4% N-ethylmorpholine selectivity 88.5% Example 2 241g of aluminum chloride hexahydrate and 85% phosphoric acid
2.9g was dissolved in 5 water, and while stirring the solution, 20% ammonia aqueous solution was added dropwise to adjust the pH to 6. The obtained precipitate was filtered, washed with water, dried at 120℃, and ground into 12 meshes or less, 5 mm in diameter and 5 mm in height.
After molding into a tablet, it is heated at 600℃ in air for 3 hours.
Baked for an hour. The proportion of phosphorus pentoxide in the catalyst obtained was 3.4%, based on the weight of the total catalyst, and the specific surface area was 330 m ² /g. When a reaction was carried out using this catalyst in the same manner as in Example 1, the following results were obtained.
The yield of ethylmorpholine was 87.5%. N-ethyldiethanolamine conversion rate 99.3% N-ethylmorpholine selectivity 88.1% Examples 3 to 7 Colloidal alumina (manufactured by Nissan Chemical Co., Ltd., trade name, Alumina Sol 200) with an alumina content of 10 wt%,
An aqueous solution of a water-soluble salt of each metal was added dropwise while stirring, and after the addition was completed, it was evaporated to dryness on a water bath while stirring. After drying at 120°C, the tablets were crushed into 12 meshes or less, formed into tablets with a diameter of 5 mm and a height of 5 mm, and then baked in air at 450°C for 3 hours. A reaction was carried out in the same manner as in Example 1 using each of the obtained catalysts. The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1. General formula (In the formula [], R is a C ₁ to C ₂₀ alkyl group or
_C3 - _C8 cycloalkyl group) from N-alkyldiethanolamine represented by the general formula (In formula [], R has the same meaning as in formula []) When producing N-alkylmorpholine, titania, zirconia, phosphorus pentoxide, sulfur oxide, tungsten oxide, chromia, zinc oxide, The content of one or more metal oxides selected from the group consisting of manganese oxide and antimony oxide is 0.1 to 10% based on the weight of the total catalyst.
A method for producing N-alkylmorpholine, which comprises reacting in a gas phase using alumina as a catalyst. 2. The method according to claim 1, wherein the concentration of the N-alkyldiethanolamine is 1 to 50 mol%.