The method of producing lactam

 

(57) Abstract:

The invention relates to the production of aliphatic lactams, in particular E-caprolactam used in the production of polyamides. The lactam is obtained by hydrolysis with water in the vapor phase at 200 - 450°C aliphatic aminonitriles, including alkyl, C3-C12. As catalyst using alumina with a specific surface area of 10 to 280 m2/g and a volume of pores having a pore diameter of more than 500 from 10 to 45 ml/100 g Molar ratio water : aminonitriles equal to (0.5 to 50) : 1, preferably (1-20) : 1. Used catalyst provides high selectivity and has a long service life while reducing the number of regeneration cycles. 7 C.p. f-crystals, 4 PL.

The present invention relates to the receipt of the lactam by tsiklitiria hydrolysis of the corresponding aminonitriles.

Aliphatic lactams, for example, caprolactam, is a basic compound to obtain polyamides (polyamide 6 from caprolactam).

One of the known methods for producing lactams is to conduct tsiklitiria hydrolysis of the corresponding aminonitriles, in particular, aliphatic, not branched aminonitriles by PN way to get lactam in the vapor phase, when the mixture of water and aminonitriles passed through a dehydration catalyst, which is, for example, activated alumina gel silica or Biofactory acid.

Patent US 4 628 085 offers a way to get the lactam in the vapor phase, which is brought into contact aliphatic or aromatic aminonitriles and water with a catalyst based on silica in the form of spherical particles with a specific surface area BET of more than 250 m2g with an average pore diameter of less than 20 nm, and typically in the presence of hydrogen, and ammonia.

The catalysts used are known from the prior art methods allow in some cases to reach the high results on the selectivity of lactam, but at the same time may also be a rapid loss of their activity, which causes great difficulty in the industrial application of these methods.

Furthermore, the method in patent US 4 628 085 involves the use of very complex reaction mixture was held at the end of the reaction operations for separation and recycling, significantly complicating this method.

The present invention provides new catalysts of aluminum oxide is characterized by a large life and therefore, need less frequent regeneration.

More specifically, the invention relates to a process for the preparation of lactam by reacting in the vapor phase of aliphatic aminonitriles General formula (1)

NC-R-NH2, (1)

in which R means alkilinity radical with 3 to 12 carbon atoms, with water in the presence of a solid catalyst, which catalyst is aluminum oxide with a specific surface area measured by BET method, of greater than or equal to 10 m2/,

Preferably used in the method according to the invention, the aluminum oxide had a specific surface area equal to or less than 500 m2/,

Among aminonitriles formula (1) are most suitable aminonitriles, allowing you to get the lactams used as a source of raw material for polyamide 4, 5, 6 and 10, i.e., aminonitriles, in the formula which symbol indicates a linear alkalinity radical with 3, 4, 5 and 9 carbon atoms.

The preferred compound of formula (1) is 6-aminocaproate (or cupronickel), allowing to obtain caprolactam, polymerization which produces a polyamide 6.

Oxides of aluminum, suitable for COI is UP>2/g and less than or equal to 280 m2/g volume of pores of diameter greater than 500 angstroms, greater than or equal to 10 ml/100 g

The specific surface according to BET - this is the surface which is determined by nitrogen adsorption according to ASTM D 3663-78 established on the basis of method of BRUNAUER-EMMET-TELLER described in the periodical "The Journal of the American Society" (journal of the American society, 60, 309 (1938).

The volume of pores with a diameter of more than 500 represents the total volume, formed by all pores with a diameter of more than 500 This amount is measured by a method of mercury penetration, which uses the law Kelvin.

Preferably, the oxides of aluminum specified first group had a pore volume having a diameter greater than 500 greater than or equal to 20 ml/100 g, even more preferably more than or equal to 30 ml/100 g

It is preferable that the alumina of the specified first group had a specific surface area greater than or equal to 50 m2/,

Oxides of aluminum, also suitable for use in the present method, are the oxides, which have a specific surface greater than or equal to 50 m2/g and less than or equal to 280 m2/g and pore volume with a diameter of more than 70 greater than or equal to 30 ml/100 g

equal to 45 ml/100 g

It is preferable that the alumina specified second group had a specific surface area greater than or equal to 80 m2/,

Oxides of aluminum, suitable for use in this method are also oxides, which have a specific surface greater than or equal to 280 m2/g and a total pore volume greater than or equal to 15 ml/100 g

Preferably, the oxides of aluminum such third group had a total pore volume greater than or equal to 22 ml/100 g, and more preferably, it exceeded or was equal to 30 ml/100 g

In addition, the oxides of aluminum and are characterized by their acidity.

Mentioned acidity can be measured by the test for the isomerization of 1-butene to 2-butene.

This test is based on the reaction of isomerization of 1-butene to the formation of the mixture of CIS-2-butene to TRANS-2-butene at a temperature T (in this case T= 400oC).

The isomerization reaction is characterized by thermodynamic equilibrium. There are two constants:

- constant theoretical equilibrium TOT(T) calculated by the formula

< / BR>
where [butene] ek. denotes the concentration of each isomer in the equilibrium state at temperature T;

- constantaly each isomer at the outlet of the reactor at the temperature T.

Isomerizing activity (A) oxides of aluminium is determined by the activity in relation to equilibrium

.

In practice, testing is carried out in a reactor with a steam phase, operating in pulsed mode, in this case it is administered 500 mg of powdered aluminum oxide (particle size from 400 to 500 μm). The aluminum oxide was incubated for 2 hours at a temperature of 250oC in a stream of helium at a flow rate of 2.5 l/H. Then the alumina is heated to a temperature of 400oC and over alumina injected into a stream of helium 1 ml of 1-butene. Analysis of the gases at the output produced by gazofaznoi chromatography, which allows to measure the number caught 1-butene and 2-butene, CIS and TRANS.

Received isomerizing activity (A) is adjusted to the isomerizing activity of the catalyst obtained under the same conditions in the empty reactor. Adjusted isomerizing activity ACrepresents the acidity of the mentioned oxides of aluminum.

When the content of alkali or alkaline-earth metal contained in the oxide of aluminum is less than 60 mmol per 100 g of aluminum oxide, the higher the value of ACthe higher the acidity of the alumina.

As p is p, in this connection, to point to the encyclopedia KIR-OTHMER, I. 2, pp. 291-297.

The alumina used in this way, can be obtained by contacting a hydrated aluminum oxide in finely powdered form with a stream of hot gas at a temperature of from 400 to 1000oC, when the duration specified contact from fractions of a second to 10 seconds, followed by separation of the partially digidratirovannogo of aluminum oxide and hot gases. Here we can refer in particular to the method described in the American patent US 2 915 365.

You can also apply autoclaving agglomerate obtained above of aluminum oxide in aqueous medium, optionally in the presence of acid, at temperatures above 100oC, preferably at a temperature of from 150 to 250oC, during the time of 1-20 hours, then drying and calcination.

The temperature of annealing is controlled so that it was possible to obtain specific surface area and the volume of pores corresponding to the ranges of the above values.

In connection with the basic principles of obtaining aluminum oxide used in this way often contain sodium, the content of which is expressed normally in the mass of Na2 is ka, balls of crushed material, the extruded products and tableting, molding can be carried out optionally with a binder.

Can be used preferably balls of aluminum oxide obtained by the droplet coagulation. This type of beads can be obtained, for example, by the method described in the patents EP-A-0 015 801 and EP-A-0 097 539. Control over the porosity can be carried out, in particular, by the method described in the patent EP-A-0 097 539 through drip coagulation aqueous suspension or aqueous dispersion of aluminum oxide or of a solution of a basic aluminium salts are in the form of an emulsion comprising an organic phase, aqueous phase, a surfactant or emulsifier. Specified organic phase can be, in particular, hydrocarbons.

Can be used and crushed aluminum oxide. Crushed material can be obtained by crushing of any material based on aluminum oxide, for example, balls, obtained by any method (droplet coagulation, in a rotating drum or the extruded products. Control over the porosity of the crushed materials is achieved by the choice of material based on aluminum oxide.

Can be applied and the products of the former is again of aluminum oxide, moreover, this material can be obtained by rapid dehydration of hydrargillite or gel deposition of aluminum oxide. Control over the porosity of such extrudates can be accomplished by the use of aluminum oxide and conditions of receipt of aluminum oxide or regime grinding of alumina prior to extrusion so that the aluminum oxide can be mixed in the process of rubbing with a pore-forming agents. As an example, the extrudates can be prepared according to the method, opened in patent US 3 856 708.

In some cases it may be appropriate to at least a portion of the free volume of the reactor was filled with inert solids, such as quartz, in order to increase the evaporation and dispersion of the reactants.

For reaction tsiklitiria hydrolysis requires the presence of water. The molar ratio between the injected water and aminonitriles is usually 0.5 to 50, preferably 1-20. The ratio of the largest value is not critical for the invention, however, a higher ratio of almost no interest from the point of view of economy.

Aminonitriles and water may be introduced in the form of the s reagents, which then served in the mixing chamber.

You can use without any damage of any inert gas as a carrier gas, such as nitrogen, helium or argon.

The temperature of the implementation of the method according to the invention should be sufficient to maintain the reactants in the vapor state. It is usually from 200 to 450oC, preferably from 250 to 400oC.

The time of contact of aminonitriles with catalyst is not critical. It may vary depending on the equipment. Contact time is mainly from 0.5 to 200 seconds, preferably from 1 to 100 seconds.

Pressure is not critical way. For example, the process can be conducted at pressures ranging from 10-3bar up to 200 bar. Preferably, the method was carried out at a pressure of from 0.1 to 20 bar.

You can use inert under the reaction conditions solvent, for example, alkane, cycloalkane, aromatic hydrocarbon, or one of their halogenated derivatives and to ensure thus the liquid phase in the reaction stream.

The examples below illustrate the invention.

An EXAMPLE of the first heating means, holes for inlet and outlet gas streams and feed system reagents sequentially loaded 10 ml quartz, 1 ml of catalyst in powder form with a grain size distribution 0,8-1,25 µm (the nature of the catalyst are given in table 1) and again 10 ml of quartz.

Loaded so the reactor was heated to 400oWith air flow (at a flow rate of 1.5 l/h) for 2 hours. Then the reactor was cooled to 320oC (selected reaction temperature) and placed under a stream of nitrogen (at a flow rate of 1 l/h).

Then use the pump filed a mixture consisting of 6-aminocaproate (ACN) and water (weight ratio: 50/50, i.e., the molar ratio of water/ACN : 6,2). The feed rate of the mixture was 1.2 ml/h

At the exit of the reactor vapors are condensed in a glass trap at ambient temperature for 2 hours.

The final reaction mixture was analyzed by chromatography in the vapor phase.

Determined the extent of transformation (TT) aminoacetonitrile, output (RT) of caprolactam with respect to the transformed aminoacetonitrile and activity of the catalyst for 2 hours reaction time, measured in grams educated caprolactam per millimeter catalytic layer in an hour.


- aluminum oxide, 7: acidity AC(400oC)=62%; specific surface (SS)=81 m2/g; 0,0714% Na2O; volume of pores with a diameter of more than 500 27 ml/100 g

- aluminum oxide 6: - acidity AC(400oC) = 65%; specific surface (SS) = 244 m2/g; 0,0730% Na2O; volume of pores with a diameter of more than 500 12 ml/100 g

- aluminium oxide 16: acidity AC(400oC) = 65%; specific surface (SS): 314 m2/g; 0,3640% Na2O; total pore volume of 40 ml/100 g

- alumina 10: acidity AC(400oC) = 99%; specific surface (SS): 217 m2/g; 0,0030% Na2O; volume of pores with a diameter of more than 70 45 ml/100 g

Table 1 shows the results.

EXAMPLES 5-7

Repeat the experience according to examples 1-3, exploring the activity of various catalysts used for 32 hours.

Table 2 presents the values of the activity of each catalyst with increasing reaction time.

You can see that the aluminum oxide does not lose its catalytic activity for at least 32 hours.

EXAMPLES 8-21 AND COMPARATIVE EXAMPLE 1

In a cylindrical reactor with a capacity of 20 ml of pericoloso glass, set of verticchio, sequentially loaded 2 ml quartz, 5 ml of the catalyst granules 1-5 mm and again 5 ml of quartz.

Loaded so the reactor was heated to 350oC in a flow of nitrogen (at a flow rate of 5.2 l/h) for 2 hours. Then the reactor was cooled to 250oC (selected reaction temperature) and placed in a stream of nitrogen (at a flow rate of 5.2 l/h).

Then use the pump filed a mixture consisting of 6-aminocaproate (ACN) and water (molar ratio of water/ACN: 2,9). The rate of flow of the liquid mixture was 14 g/h

At the exit of the reactor vapors are condensed in a glass trap at ambient temperature for 2 hours.

The final reaction mixture was analyzed by chromatography in the vapor phase.

Determined the degree of education (TT) aminoacetonitrile, output (RT) of caprolactam with respect to the transformed aminoacetonitrile and activity of the catalyst for 2 hours reaction time, measured in grams of the resulting caprolactam per gram of catalyst per hour (activity a) and in grams of the resulting caprolactam per milliliter catalytic layer per hour (activity b).

The degree of conversion of 6-aminocaproate is 25 to 40% of acteristic of aluminum oxide, used as catalysts (specific surface SS, total pore volume VPT, the volume of pores with a diameter of more than 500 = V500A volume of pores with a diameter of more than 70 = V70 , and the activity values a and b of different types of aluminum oxide are shown in table 3.

EXAMPLES 22 - 28

In the reactor described in the previous examples, sequentially loaded 3 ml quartz, 2 ml of the catalyst granules from 1 to 5 mm and again 5 ml of quartz.

Loaded so the reactor was heated to 350oC in a flow of nitrogen (at a flow rate of 5.2 l/h) for 2 hours. Then the reactor was kept at 350oC (selected reaction temperature) and placed in a stream of nitrogen (at a flow rate of 5.2 l/h).

Then use the pump filed a mixture consisting of 6-aminocaproate (ACN) and water (molar ratio of water/ ACN: 1,1). The feed rate of the mixture was equal to 11 g/h

At the exit of the reactor vapors are condensed in a glass trap at ambient temperature within the time listed in the following table 4.

The final reaction mixture was analyzed by chromatography in the vapor phase.

Determined the extent of transformation (TT) aminoacetonitrile, output (RT) of caprolactam in relation to the converted amiocap the Osia caprolactam per gram of catalyst per hour (activity a) and in grams of the resulting caprolactam per milliliter catalytic layer per hour (activity b).

The degree of conversion of 6-aminocaproate presented in table 4, the output RT in examples 22-28 amounted to more than 90%.

1. The method of producing lactam by reacting in the vapor phase of aliphatic aminonitriles General formula:

N C-R-NH2< / BR>
in which R means alkilinity radical with 3 to 12 carbon atoms, with water in the presence of a solid catalyst, wherein the catalyst is aluminum oxide with a specific surface area measured by the method of WET, above or equal to 10 m2/g, while the oxide is chosen from: a) oxides of aluminium with a specific surface area less than or equal to 280 m2/g and a volume of pores having a diameter greater than 500 greater than or equal to 10 ml/100 g; (b) alumina with a specific surface area greater than or equal to 50 m2/g and less than or equal to 280 m2/g, and the volume of pores having a diameter greater than 70 greater than or equal to 30 ml/100 g

2. The method according to p. 1, characterized in that the aluminium oxide selected from oxides of aluminium (a) with a volume of pores having a diameter greater than 500 greater than or equal to 20 ml/100 g, preferably more than or equal to 30 ml/100 g

3. The method according to p. 1 or 2, characterized in that the aluminium oxide selected from oxides of aluminium (a) with a specific surface area above or RA is I b) having a volume of pores with diameters of more than 70 greater than or equal to 45 ml/100 g

5. The method according to PP.1 to 4, characterized in that the aluminium oxide selected from oxides of aluminium (b) with a specific surface greater than or equal to 80 m2/,

6. The method according to PP.1 to 5, characterized in that aminonitriles formula (I) is 6-aminocaproate.

7. The method according to PP.1 - 6, characterized in that the molar ratio between the injected water and aminonitriles is from 0.5 to 50, preferably from 1 to 20.

8. The method according to PP.1 to 7, characterized in that the temperature at which carry out the method, is from 200 to 450oC, preferably from 250 to 400oC.

 

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