CS200834B1 - Method of producing alkanolamines - Google Patents

Description

The invention relates to a process for the preparation of alkanolamines, preferably ethanolamines and isopropanolamines, from the corresponding alkylene oxide and ammonia.

Alkanolamines are important organic products used in various industries. Alkanolamines have amine and alcohol properties from a flame retardant site. In particular, two main groups of alkanolamines, namely ethanolamines and isopropanolamines, are produced industrially, the major part of the steel production being ethanolamines.

These are monoethanolamine, dletanolamine and triethanolamine.

It is known that industrially alkanolamines are produced by reacting alkylene oxide with an aqueous ammonia solution. As alkylene oxides, they are primarily used in industrial practice

1,2 alkylene oxides having a court or three atoms per molecule, i. ethylene oxide and propyl oxide.

It is also known that in the reaction of alkylene oxide with ammonia, a mixture of mono-, dia-trialkanolamine is formed, the ratio being dependent on the molar ratio of ammonia to alkylene oxide used in the reaction. A typical process for producing alkanolamines by reacting alkylene oxide with aqueous ammonia is described in GB-700215.

Since the ratio of the individual alkanolamines produced in the synthesis, which is clearly determined by the ammonia: alkylene oxide molar ratio used, does not correspond to the needs, it was necessary to look for new methods of producing alkanolamines that would allow the production of individual alkanolamines in accordance with changing needs.

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In the current state of the art, the problem of modifying the production of alkanolamines so that the production of the individual alkanolamines corresponds to their consumption can essentially be solved by the court.

First. oesta is oxyalkylene of mono or dlalkanolamine in anhydrous medium for trialkanolamine or oxyalkylated of monoalkanolamine for dialkanolamine. The oxyalkylene is carried out in a continuous manner at a temperature of from 30 ° C to 200 ° C and a pressure of up to 3.5 MPa to separate the devices of the various constructions with a continuous continuous process.

U.S. Pat. No. 2,602,819 describes the preparation of triethanolamine from mono or diethanolamine with ethylene oxide in an anhydrous and ammonia-free environment at a temperature of max. to 100 ° C. According to German Patent No. 2,307,902, triethanolamine can be prepared by a continuous epidsoby from mono or diethanolamine in anhydrous medium and in the absence of ammonia by reaction with ethylene oxide at a temperature of 110 ° C to 18 ° C, the reaction time being limited to max. 2 hrs and the synthesis is carried out at least in the dehumidifier, respectively. trooh reaction prtotorooh.

German Patent 2,535,328 discloses a continuous process for the preparation of dialkanolamines, according to which in the first reactor the monoalkanolamine is synthesized from alkylene oxide and aqueous ammonia solution at a temperature of 40 to 150 ° C and a pressure of 2.1 to 14.6 MPa and after the monoalkanolamine is separated. The monoalkanolamine column is fed to the second reaction space where it reacts with alkylene oxide to dialkanolamine in an anhydrous and ammonia-free environment at a temperature of 40 to 200 ° C and a pressure of 0.35 to 3.5 MPa.

The other ways of addressing this are the ways in which the regulation of the individual products is effected by returning a portion of the mono or dlalkanolamine produced to the reaction system. When the monoalkanolamine is returned to the reaction system, the production of di- and trialkanolamine is reduced. The amount of alkylene oxide depends on the molar ratio of ammonia: alkylene oxide in the reaction mixture. This method is described in U.S. Pat. No. 2,622,099.

When dlalkanolamine is returned to the reaction system, a reduction in the production of dl- and an increased production of trialkanolamine is achieved. A process for producing alkanolamines with dialkanol-fmi backing to the reaction system is disclosed in U.S. Pat. No. 2,622,073.

It follows that, according to the current state of the art, by boiling mono- or diethanolamine and by correspondingly changing the ammonia: ethylene oxide molar ratio in the synthesis, it is possible to achieve a composition of production which is in accordance with the requirements of the customers.

It also follows that the modification of the composition of the products entails an increase in the production of theavins for the costs associated with the poor return of mono- or diethanolamine and 1 regeneration of ammonia, in particular as in the landfill, a significant proportion of monoethanolamine.

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Obeone thus applies both to the continuous production of otanolamines and to the discontinuous oxyethylate of mono- or di-ethanolamines. According to known processes for modifying the composition according to the requirements of the customers, this has resulted in increased costs due to the disadvantages of vraoanal or oxyethylamino mono- or di-ethylamino. The basic disadvantages include:

(a) Mono- or di-ethanolamine must be isolated as pure products, that is to say that the capaoity will be reduced by the amount of otanolamine that has been injected and thus the production of products for disposal.

(b) Energy consumption per unit of goods shall be increased by the share of energy consumption for the increased production of the product returned.

o) The energy consumption will increase 1 due to the overpowered ammonia excess which is reflected! in increasing the amount of ammonia and water boiling.

d) In discontinuous oxyethylation, the above disadvantages in points (a) to (o) above are in addition to the need for a complete oxyothylating device, including its operation.

Another disadvantage of the oxyalkyleneol in the anhydrous environment, both in the continuous and discontinuous process, in addition to the need for a separate oxyalkylation device, is the formation of significant amounts of amounts unnecessary to the side products, resulting from the subsequent reaction of trlalkanolamine with ethylene oxide.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for the production of alkanolamines which allows modification of the production composition in a more efficient manner and without oxyalkyleneol of a portion of the mono- or di-ethanolamine produced in an anhydrous medium. np. a separate oxyalkylation device,

The initial disadvantages are eliminated by the process for the production of alkanolamines, preferably otanolamines and isopropanolamines, by reacting an aqueous solution of ammonia with 1,2 or more carbon atoms of the invention according to the invention, which is essentially carried out at a temperature of 20 to 16 ° C and a pressure of 0.01 up to 5 MPa in two separate stages, wherein the first stage is carried out at a molar ratio of ammonia: alkylene oxide of 1: 25: 1 and a part of the reaction mixture or the other reaction mixture from the first stage is fed to the second reaction stage in which it reacts with the alkylene oxide in an amount of 0.02 to 1.05 mol of alkyl oxide per 1 mol of hydrogen bound to nitrogen.

Compared to the one-step synthesis used in the known processes and who the alkanolamine amine ratio is unequivocally determined by the ammonium: alkylene oxide molar ratio used, the production method of the present invention allows the optimization of the process flow through a number of variables, namely:

- the ammonia: alkylene oxide molar ratio in the first reaction stage,

- the amount of alkylene oxide fed to the second reaction stage,

a plurality of reaction mixtures, fed to the subsequent reaction with alkylene oxide to the second reaction stage.

The proposed new process for the production of alkanolamines makes it possible to use additional strands to modify the composition of the production process, including the addition of mono- or triethanolamine;

200,034% of the alkanolamine mixture back to the second annual stage.

In the proposed process for the production of alkanolamines in two and one reaction steps in series, in the first step only the synthesis of alkanolamines by reaction with ammonia solution with alkylene oxide is carried out and in the second reaction step the modification of the production composition of the oxyalkylated reaction mixture is carried out. In the second reaction stage, the reaction of the alkylene oxide and the mono and dlalkanolamine is carried out, as well as the 1-reaction of the alkylene oxide and the ammonia used in the first step in excess. That is, in the second reaction step, in addition to modifying the composition of the process, a further partial increase in the concentration of the annual solution is achieved, notably due to oxyalkylene mono and dialkanolamine, but also due to roaco ammonia and alkylene oxide resulting in more alkanolamines.

By comparison with the current state of the art, in the proposed process for the production of alkanolamines, it is possible to significantly reduce or even eliminate the return of mono or dialkanolamines as finished products back to the production process, and reduce the amount of recovered ammonia and water per unit of production and thus more. reducing energy consumption and apparatus sizes for separating ammonia and water from the reaction mixture, and re-injecting it into the production prooose. Thus, the advantages of the two-step synthesis will greatly increase the production capacity of the plant and reduce the cost of production, especially when the production is contaminated with lower monoalkanolamine content and higher trlalkanolamine content. In addition, with mono and dlalkanolamine alkylene oxide in the presence of aqueous ammonia solution. degree, don't talk! The amount of alkalta of the trialkanolamine is as much as in the anhydrous medium, and thus the undesirable formation of trlalkanolamine ethers is suppressed.

The invention is illustrated by the following examples.

Example t

The preparation of the otanolamines is carried out in a continuous manner by contacting an aqueous solution of ammonia and ethylene oxide in two separate reaction steps. Aqueous ammonia solution is continuously metered into the first annual step. 28 wt. and otylene oxide in a 5: 1 molar ratio of ammonia: otylene oxide. The reaction temperature is maintained at 35 to 40 ° C and the pressure at 0.15 MPa. In the reaction of ammonia with otylene oxide, a mixture of 38% by weight of otanolamines is produced in the first step. % monoethanolamine, 33.3 wt. % diethanolamine and 28.7 wt. triotanolamínu. The aqueous solution of the otanolamines formed in the first reaction step contains, in addition to the otanolamines, soluble ammonia used in excess of the reaction with otylene oxide. The reaction mixture of the first stage is divided into two parts. One part at 55 volume, is fed to the second annual stage, and the other part at 45 # volume, was fed to the plant for the ammonia and water sections and regonorations.

In the second reaction step, at a temperature of 40 ° C and a pressure of 0.01 MPa, the ethylene oxide is continuously reacted with ammonia, monoethanolamine and diethylamine contained in the reaction mixture from the first step. The ethylene oxide dosage is continuous

200,034 in an amount of 0.92 moles per mole of hydrogen bound to nitrogen in ammonia, mono- and diethanolamine,

The reaction mixture formed in the second reaction step is an aqueous solution of a mixture of ethanolamines in a ratio of 11% by weight. mono. 14 $ wt. di- and 75 wt. triethanolamine and ammonia used in the reaction in excess. The aqueous solution leaving the second reaction stage is fed to an apparatus for separating and recovering ammonia and water.

Example 2

Procedure similar to Example 1. In the first reaction step, the reaction is carried out at a molar ratio of ammonia: ethylene oxide of 2: 1. The reaction solution contains a 20% by weight mixture of ethanolamines. % mono-, 20.7 $ wt. di- and 59.3 wt. triethanolamine.

The entire amount of the reaction mixture resulting from the first reaction stage is fed to the second reaction stage where it is reacted with ethylene oxide in an amount of 0.99 moles of ethylene oxide per mole of nitrogen bound hydrogen. The reaction solution formed in the second reaction stage comprises a mixture of ethanolamine % in a ratio of 5.2 wt. % mono-, 7.5 phy. dl- and 86.9% by weight of triethanolamine.

Example 3

Procedure similar to Example 1. Propylene oxide is used as the starting 1,2 alkylene oxide. In the first reaction step, the reaction is carried out at a molar ratio of ammonia: propylene oxide of 4: 1 and at a temperature of 65 ° C and a pressure of 0.4 to 0.5 MPa. The reaction solution contains a mixture of isopropanolamines in a ratio of 48% by weight, mono-, 12.5% by weight. % di- and 39.5 phy. triisopropanolamine. 60 phy by volume of the reaction solution is fed to the second reaction stage and 40 phy by volume are fed to a device for separating and recovering ammonia and water.

In the second reaction step, at 60 to 65 ° C and a pressure of 0.2 to 0.3 MPa, the propylene oxide is reacted continuously with the ammonia, monoisopropanolamine, contained in the reaction mixture fed from the first step. The metering of propylene oxide is continuously in an amount of 0.66 mol per 1 mol of hydrogen bound to nitrogen.

The reaction mixture formed in the second reaction step comprises an aqueous solution of a mixture of isopropanolamines in a ratio of 14% by weight. % mono-, 46 phy wt. di- and 40 fy bmotn. triisopropanolamine.

Example 4

Procedure similar to Example 1. An aqueous ammonia solution was added continuously to the first reaction step. 37 phy wt. and ethylene oxide in a molar ratio of ammonia: ethylene oxide of 8: 1. The reaction temperature is maintained at 148 ° C and the pressure at 4.7 MPa. The reaction solution contains a mixture of ethanolamines in a ratio of 50 phy. mono-, 31 phy, di- and 19 phy. triethanolamine.

fy by volume of the amount of the reaction mixture produced in the first reaction stage,

O is fed to a second reaction stage, where it is reacted with ethylene oxide in an amount of 0.62 moles of ethylene oxide per mole of nitrogen bound hydrogen at 147 DEG C. and a pressure of 4.5 MPa. The reaction solution formed in the second reaction step comprises a mixture of ethanolamines β

200-3% in a ratio of 17% by weight, mono-, 37% by weight, di- and 45% by weight of trlethanolamine.

Example 5

Procedure similar to Example 1. An aqueous ammonia solution was added continuously to the first reaction step. 33 wt. and ethylene oxide in a molar ratio of ammonia: ethylene oxide 2511. The reaction temperature is maintained at 153 ° C and the pressure at 4.8 MPa. The reaction solution contains a mixture of ethanolamines in the posterior · 88 wt. % mono-, 8.5 wt., dia 3.5 wt. trletanolamínu.

% by volume of the amount of the reaction mixture formed in the first reaction stage is fed to the second reaction stage, where it is reacted at 153 ° C and a pressure of 4.8 MPa with ethylene oxide in an amount of 1 mole ethylene oxide per mole of hydrogen bound to the hydrogen. The reaction solution formed in the second reaction step comprises a mixture of ethanolamines in a ratio

4.6 wt. % mono-, 7.1 wt. di- and 88.1% by weight of trlethanolamine.

Claims (2)

1. A process for the production of alkanolamines, preferably ethanolamines and isopropanolamines, by reaction of aqueous ammonia with 1,2 alkylene oxide having a backbone or three carbon atoms, characterized in that the reaction is carried out at a temperature of 20 to 16 ° C and a pressure of 0.01 to 5 MPa in The reaction is carried out at a molar ratio of ammonia to alkylene oxide of 1: 25: 1 and a part of the reaction mixture or the entire reaction mixture of the first stage is fed to the second reaction stage in which it reacts with the alkylene oxide in an amount of 0. 02 to 1.05 mol of alkylene oxide per 1 mol of hydrogen bound to nitrogen, 2. The process for producing alkanolamines according to claim 1, characterized in that a monoalkanolamine or a dialkanolamine or a mixture thereof is fed to the second reaction system from the dellaoo system.