JPH0513700B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a gas phase intramolecular dehydration catalyst used for converting alkanolamines represented by the general formula () into cyclic amines represented by the general formula (). (In the formula, R and R' are each selected from the group consisting of hydrogen, methyl group, and ethyl group, and n is an integer in the range of 2 to 5.) The cyclic amines represented by () above are generally: Since it is highly reactive and reacts with compounds having various functional groups, it is possible to produce various derivatives having amino groups. Furthermore, since a ring-retaining reaction is also possible, derivatives having ring-opening reactivity can also be produced. Furthermore, polyamine-based polymers can also be produced by ring-opening polymerization reaction, making it a highly useful compound. Derivatives of cyclic amines are extremely useful compounds that are widely used in various industries as textile processing agents, antistatic agents, raw materials for pharmaceuticals and agricultural chemicals, and the like. The present invention
The present invention provides a high-performance catalyst for producing cyclic amines, which are such useful compounds, by intramolecular dehydration reaction of alkanolamines in the gas phase, which is very advantageous in terms of productivity. [Prior art] Methods for converting alkanolamines into cyclic amines through a dehydration reaction include a method of intramolecular ring-closing of a halogenated amine with a concentrated alkali (Gabriel method), a method of intramolecular ring closure of a halogenated amine with a concentrated alkali, and a method of converting an alkanolamine sulfate with a hot concentrated alkali. Method of ring closure (Wenker
However, these methods have low productivity because they use a large amount of alkali in the form of a concentrated solution, and the basic unit of alkali in the raw material cost is large. There are many problems industrially, such as by-products. In recent years, monoethanolamine has been used as the alkanolamine for the liquid phase method described above,
Several attempts have been reported to dehydrate this in the gas phase in the presence of a catalyst to continuously produce the corresponding cyclic amine, ie, ethyleneimine. For example, in Special Publication No. 50-10593,
A method using a tungsten oxide catalyst is described, and US Pat. No. 4,301,036 describes a method using a catalyst consisting of tungsten oxide and silicon, and US Pat.
No. 4337175 and No. 4477591 each disclose a method using a niobium or tantalum catalyst. However, in all of these methods, the conversion rate of monoethanolamine is low, and even when the conversion rate is relatively high, the proportion of products due to side reactions such as deammonification reaction and dimerization reaction is high, so it is difficult to select ethyleneimine. gender has become low. Furthermore, according to the studies conducted by the present inventors, as far as the life of the catalyst is concerned, in all cases, the activity decreases significantly in a short period of time, which is completely unsatisfactory from an industrial point of view. [Structure of the present invention] As a result of extensive research into catalysts for gas-phase intramolecular dehydration reactions of alkanolamines, the present inventors found that a trace amount or equivalent amount of alkali metal and/or
or the general formula SiaXbOc (where Si is silicon and X is one or more elements selected from alkali metals and/or alkaline earth metals). , O represents oxygen. Subscripts a, b, c
indicates the atomic ratio of each element, and when a=1, b=0.005 to 1 (preferably b=0.01
~0.5), and c takes a value determined by a and b. ) By using the oxide catalyst represented by the formula, the gas phase intramolecular dehydration reaction of alkanolamines proceeds extremely favorably, and the desired cyclic amines can be produced with high selectivity and yield over a long period of time. The present invention was completed by discovering that it can be produced stably. The catalyst of the present invention effectively acts on the gas phase intramolecular dehydration reaction, and the alkanolamines used as reaction raw materials have the general formula (In the formula, R and R' are each selected from hydrogen, a methyl group, and an ethyl group, and n takes an integer in the range of 2 to 5.) Preferred are alkanolamines represented by these. Examples include (a) monoethanolamine, (b) isopropanolamine, (c) 3-amino-1-propanol, (d) 5-
Amino-1-pentanol, (e)2-amino-1-
Examples include, but are not limited to, butanol. These amines according to the invention have the general formula (In the formula, R, R' and n are the same as the formula.) Corresponding to the above compounds, (a') ethyleneimine and (b') 2-methyl-ethylene, respectively. It is stably converted to imine, (c') azetidine, (d') piperidine, and (e') 2-ethyl-ethyleneimine with high conversion and high selectivity over a long period of time. The method for preparing the catalyst according to the present invention is not particularly limited, and a commonly used preparation method can be used. As the alkali metal and/or alkaline earth metal element source which is the X component of the catalyst raw material, oxides, hydroxides, halides, carbonates,
Sulfates, nitrates, etc. are used, and silicon sources include silicon oxide, silicon halides,
Silicic acid, silicates, silicon oxide sols, organosilicon compounds, etc. are used. An example of the method for preparing the catalyst according to the invention is:
Various catalyst raw materials are dissolved or suspended in water,
A method of heating and concentrating under stirring, drying, molding, and further calcination to make a catalyst, or dissolving or suspending various catalyst raw materials in water and making a hydroxide by adding aqueous ammonia, followed by filtration and washing with water. There is a method in which oxides or hydroxides of various elements are mixed in powder form and an appropriate molding aid (e.g. water, alcohol, etc.) is added. Examples include a method of post-molding, drying, and firing. Further, the catalyst according to the present invention can also be used by being supported on a known inert carrier (for example, silica, alumina, Celite (trade name), etc. are preferable, but not limited to these). The firing temperature of the catalyst may vary widely from 300°C to 800°C, preferably from 400°C to 700°C, although it depends on the type of raw materials used. [Function] When the catalyst of the present invention is used in the gas phase intramolecular dehydration reaction of alkanolamines, it exhibits extremely high activity compared to conventionally known catalysts, and the selectivity for the target cyclic amine is also extremely high. It was hot. Moreover, even when this reaction is carried out continuously for a long time, no deterioration of catalyst activity is observed, and both activity and yield are extremely stable, and short-term deterioration phenomenon is the most important for industrialization. This was a sufficient solution to the problem of overcoming this problem. The catalytic performance was evaluated using known catalysts for ethyleneimine synthesis from monoethanolamine (for example, WO ₃ -SiO ₂ and Nb ₂ O ₅ -BaO shown in Japanese Patent Publication No. 50-10593 and U.S. Pat. No. 4,337,175). When compared with other composition catalysts, the performance of the catalyst according to the present invention was significantly superior to those catalysts in terms of both activity and selectivity. Although the details of the reason why the catalyst according to the present invention exhibits extremely excellent performance in the gas phase dehydration reaction from alkanolamines to cyclic amines are not clear, the present inventor has discovered that an alkali metal, which is an essential component, It is speculated that the effects of and/or alkaline earth metal elements are significant. That is, oxides of alkali metals and alkaline earth metals have basicity due to bridging oxygen atoms or surface hydroxyl groups,
The base site allows the generated cyclic amine to be quickly removed from the catalyst surface, thereby suppressing sequential polymerization reactions or decomposition reactions. The properties of the acid sites of silicon, which is an acidic component element, are appropriately controlled to suppress side reactions such as deammonia and intermolecular condensation reactions caused by too strong acid sites. It is thought that the basic site promotes the hydrogen abstraction reaction from the amino group and has the effect of improving the activity. Therefore, on the catalyst of the present invention, the reaction proceeds effectively due to acid-base cooperation, and at the same time , product desorption becomes smoother, deactivation due to poisoning of strongly adsorbed substances on the catalyst is suppressed, and the desired cyclic amine can be produced stably over a long period of time with high conversion and high selectivity. It is considered possible. More specifically, for example, when a=1, b
= in the range of 0.005 to 1, and when b = less than 0.005, even if an alkali metal and/or alkaline earth metal is added, there is little improvement in both the reaction conversion rate and the selectivity of the target product, and b = When it exceeds 1, although the reaction conversion rate is significantly improved, the selectivity of the target product is not improved. In either case, the balance between acid sites and base sites of the catalyst is lost, which is undesirable. In carrying out the present invention, the reactor is a fixed bed flow type,
Any fluidized bed type can be used. The raw material alkanolamines are diluted with an inert gas such as nitrogen, helium, or argon to a concentration of 1 to 80% by volume, preferably 2 to 50% by volume, as necessary. Further, in some cases, ammonia, water, or the like may be supplied together with alkanolamines for the purpose of suppressing side reactions. The reaction is usually carried out under normal pressure, but can also be carried out under increased or reduced pressure if necessary. The reaction temperature varies depending on the type of raw material, and is
~500℃ range. The space velocity of the raw material gas varies depending on the type of raw material and the concentration of the raw material gas, but
A range of 100 to 500 hr ^-1 , preferably 500 to 3000 hr ^-1 is suitable. The present invention will be specifically described in Examples below, and the conversion rate, selectivity, and single flow yield in the Examples shall comply with the following definitions. Conversion rate (mol%) = Number of moles of alkanolamine consumed/Number of moles of alkanolamine fed x 100 Selectivity (mol%) = Number of moles of cyclic amine produced/Number of moles of alkanolamine consumed ×100 Single flow yield (mol%) = number of moles of cyclic amine produced/
Number of moles of alkanolamine supplied x 100 Example 1 0.58 g of magnesium hydroxide and 30 g of silicon oxide were suspended in 100 ml of water, and heated and concentrated at 90° C. with thorough stirring to obtain a white slurry mixture. After drying this in air at 120°C overnight, it was crushed into 3.5 meshes and calcined at 600°C for 2 hours to obtain a catalyst. After filling 20 ml of this catalyst into a stainless steel reaction tube with an inner diameter of 16 mm, it was immersed in a molten salt bath at 370°C, and the volume ratio of monoethanolamine:nitrogen = 5:
The reaction was carried out by passing 95 raw material gases at a space velocity of 1500 hr ^-1 . The reaction product was quantified by gas chromatography, and the results shown in Table 1 were obtained. Example 2 A catalyst was prepared in the same manner as in Example 1, except that 1.11 g of calcium hydroxide and 30 g of silicon oxide were used as catalyst raw materials. Using this catalyst, monoethanolamine and isopropanolamine were reacted based on the reaction conditions of Example 1. The results are shown in Table 1. Example 3 A catalyst was prepared in the same manner as in Example 1, except that 13.28 g of strontium hydroxide (octahydrate), 1.02 g of rubidium hydroxide, and 30 g of silicon oxide were used as catalyst raw materials, and monoethanolamine and The reaction of 3-amino-1-propanol was carried out according to Example 1, and the results shown in Table 1 were obtained. Example 4 Barium hydroxide (octahydrate) as catalyst raw material
Example 1 except that 63.1g and 30g of silicon oxide were used.
A catalyst was prepared in the same manner as above, and a continuous reaction of monoethanolamine was carried out based on the reaction conditions of Example 1, and the results shown in Table 1 were obtained. Comparative Example 1 A catalyst was prepared in the same manner as in Example 1 using only 30 g of silicon oxide as a catalyst raw material. Using this catalyst, a reaction was carried out according to the reaction in Example 1, and the results shown in Table 2 were obtained. Comparative Example 2 40 g of silicon carbide with a diameter of 5 mm was immersed in 65.2 g of ammonium metatanxstate aqueous solution (50 wt% based on WO ₃ ), evaporated to dryness on a hot water bath, and then dried in air at 150°C for 1 hour. even more in the air
A catalyst precursor was obtained by calcining at 715°C for 4 hours. This was immersed in 50 ml of 10% silicon oxide colloid, evaporated to dryness on a hot water bath, dried in air at 150°C for 1 hour, and then calcined in air at 715°C for 4 hours. A supported catalyst containing 3.3% by weight of silicon (W _1.0 Si _0.5 O _4.1 in atomic ratio) was obtained. Using this catalyst, monoethanolamine was reacted based on the reaction conditions of Example 1, and the results shown in Table 2 were obtained. Note that this catalyst was prepared according to Example 4 described in US Pat. No. 4,301,036. Comparative Example 3 After completely dissolving 5.0 g of niobium pentachloride in 50 ml of water while heating at 60°C, aqueous ammonia was added,
The pH of the solution was set to 7.0. Thereafter, the solid obtained through filtration and water washing was dissolved in 80 ml of a 10% by weight oxalic acid aqueous solution, and further barium hydroxide (octahydrate) 0.2
g was added. silicon carbide 60 in this solution
500 cc in air after soaking and evaporating to dryness at 80℃
A supported catalyst (atomic ratio) containing 3.7% by weight of niobium pentoxide and 0.5% by weight of barium oxide was calcined at ℃ for 3 hours.
Nb _1.0 Ba _0.1 O _2.6 ) was obtained. Using this catalyst, a reaction was carried out based on Example 1, and the results shown in Table 2 were obtained. Note that this catalyst was prepared according to Example 3 described in US Pat. No. 4,477,591. Example 5 A catalyst was prepared in the same manner as in Example 1 using 0.28 g of potassium hydroxide and 30 g of silicon oxide as catalyst raw materials. Using this catalyst, the reaction of monoethanolamine and 2-amino-1-butanol was carried out based on the reaction conditions of Example 1.
The results shown in 1 were obtained. Example 6 As a catalyst raw material, 0.58 g of magnesium hydroxide,
A catalyst was prepared in the same manner as in Example 1 using 0.20 g of sodium hydroxide and 30 g of silicon oxide. Using this catalyst, monoethanolamine and 5-
The reaction of amino-1-pentanol was carried out based on the reaction conditions of Example 1, and the results shown in Table 1 were obtained. Example 7 A catalyst was prepared in the same manner as in Example 1 using 0.37 g of calcium hydroxide, 3.94 g of barium hydroxide (octahydrate), and 30 g of silicon oxide as catalyst raw materials. Using this catalyst, the reaction of monoethanolamine and isopropanolamine was carried out in Example 1.
The reaction was carried out under the following reaction conditions, and the results shown in Table 1 were obtained. Example 8 As catalyst raw materials, 0.75 g of cesium hydroxide, 4.73 g of barium hydroxide (octahydrate), and silicon oxide
A catalyst was prepared in the same manner as in Example 1 using 30 g. Using this catalyst, a continuous reaction of monoethanolamine was carried out based on the reaction conditions of Example 1, and the results shown in Table 1 were obtained.

【table】

【table】

[Table] Example 9 Using the catalyst of Example 8, the monoethanolamine concentration in the supplied raw material gas was 100%, and the reaction temperature was 400.
℃, reaction pressure 60mmHg, space velocity 100hr ^-1 (STP)
Intramolecular gas-phase dehydration reaction of monoethanolamine was carried out. Analysis of the product 1 hour after the start of the reaction revealed that the monoethanolamine conversion rate was 56.3 mol%, the ethyleneimine selectivity was 72.0 mol%, and the ethyleneimine single flow yield was 40.5 mol%.

Claims (1)

[Claims] 1. A general formula formed by adding a trace or equivalent amount of one or more elements selected from alkali metals and/or alkaline earth metals to silicon.
SiaXbOc (where Si is silicon and X is 1 selected from alkali metals and/or alkaline earth metals)
The species or more elements, O, represent oxygen. Subscripts a, b, c indicate the atomic ratio of each element,
When a=1, b=0.005 to 1, and c
takes a value determined by a and b. ), characterized in that it is an oxide composition represented by the general formula (In the formula, R and R' are each selected from hydrogen, a methyl group, and an ethyl group, and n takes an integer value in the range of 2 to 5.) Alkanolamines represented by the general formula (In the formula, R, R' and n are the same as in the above formula ()).