CS209761B1 - Method of preparing 2-ethyl hexanol - Google Patents

Abstract

The invention is within the field of petrochemical synthesis. Process for preparing 2-ethylhexanol according to the invention The invention is based on the fact that 2-ethylhexanol is present obtained by catalytic hydrogenation of 2-ethylhexenal at an elevated temperature of 200 to 290 ° C and at an elevated pressure of 10 to 30 MPa in the presence zinc-containing catalyst; chromium, which additionally contains copper oxide. Weight ratio copper oxide: oxide zinc: the oxide of the zinc (12.3 to 54): (11.0-52.2): (6-23.2).

Description

The present invention relates to a process for the preparation of 2-ethylhexanol by hydrogenation of 2-ethylhexenal.

2-Ethylhexanol is widely used as a solvent for natural and synthetic resins, as a component for fuel and oil additives, ester lubricants and emulsifiers, flotation and extraction agents. Especially preferred is the treatment of 2-ethylhexanol into esters, in particular phthalates, which are used as plasticizers for vinyl polymers, in particular for polyvinyl chloride. Plasticizers based on 2-ethylhexanol are advantageously characterized by a number of valuable properties over other plasticizers. They have low solubility in water, stability at elevated temperature, frost resistance, good color stability, resistance to aging.

It is known to produce 2-ethylhexanol by hydrogenating 2-ethylhexenal on a chromium-chromium catalyst (GB-A-1,097,819) at 165 ° C and 10 MPa.

The process is carried out with a high degree of conversion and high selectivity. However, the catalyst is particularly unstable and the presence of minute impurities in 2-ethylhexenal, such as acids, water, cobalt and iron traces, leads to cell disruption or rapid loss of activity. In addition, the spatial feed rate of the feedstock does not exceed 0.2 h ^-1 .

It is also known to produce 2-ethylhexanol by condensation of n-butyraldehyde in the presence of alkali followed by rectification of the condensate and hydrogenation of the obtained 2-ethylhexenal on a nickel-chromium catalyst at a temperature of 150-170 ° C at atmospheric pressure (GB patent. 1,244,442). The addition of nickel to the chromium-chromium catalyst makes it possible to obtain 2-ethylhexanol which is almost free of unsaturated compounds. Spatial velocity (0.18 h -1) and stability to the effect of noxious impurities, however, remain at the level of the chromium-chromium catalyst.

Disclosed is the hydrogenation of 2-ethylhexenal on a catalyst comprising a silica-based catalyst at a temperature of 125 ° C, a pressure of 3 to 5 MPa and a space velocity of 0.3 h ^- (GB patent specification 1 219 038). However, the yield of the end product, 2-ethylhexanol, does not exceed 80% due to the low degree of conversion of the 2-ethylhexenal used.

A process for the hydrogenation of 2-ethylhexenal on a catalyst containing copper on diatomaceous earth at a temperature of 160 ° C is known (FR Patent 2,058,532). This catalyst is also characterized by low space velocity and low stability to the effects of acids, water, cobalt traces and iron.

The 2-ethylhexenal obtained by condensation of pure n-butyraldehyde in the presence of alkali and subsequent rectification of the condensate contains virtually none of the harmful impurities mentioned and can be hydrogenated to 2-ethylhexanol on said copper-containing catalysts without reducing their activity and stability.

Now, however, the raw materials for the synthesis of 2-ethylhexanol have greatly expanded. New methods for producing 2-ethylhexenal from n-butyraldehyde synthesized by oxosynthesis without prior separation of n-butyraldehyde from the hydroformylation product, for example using cobalt salts circulating in the oxosynthesis process as a condensation catalyst (USSR Certificate No. 258,296; USSR copyright certificate No. 559 547).

In carrying out the process in this manner, a fraction of dimeric products is separated from the condensation catalyst, which in addition to 2-ethylhexenal contains admixtures of butyric acids, water, esters and other secondary process products, cobalt admixture and iron. The catalysts mentioned above are not suitable for the hydrogenation of such products.

A significant disadvantage of such catalysts is, moreover, the low spatial feed rate of the feedstock (0.2 to 0.3 h -1).

It is also known to synthesize 2-ethylhexanol by condensation on the cobalt salts of n-butyraldehyde, obtained by oxosynthesis and subsequent two-stage hydrogenation of the condensate obtained (USSR Authorization Certificate No. 406 823). . .

The hydrogenation is carried out in the first step in the presence of a zinc-chromium catalyst, for example AlZnCr, at a temperature of 280 to 290 ° C, at a pressure of 30 MPa, and in the second step in the presence of a copper or nickel catalyst at a temperature of 30 MPa. The use of a zinc-containing catalyst allows the space velocity to be increased to 1.5 to 2 h -1. In addition, the zinc-rich catalyst is not susceptible to acid, cobalt and iron poisoning and has high mechanical strength.

Additives of hydroformylation by-products (butyric acids, esters, acetals) are not harmful to the zinc and chromium catalyst, but are hydrogenated from 70 to 90% to valuable butanol alcohols which have a separate use, which significantly improves the technical-economic value of the synthesis process 2-ethylhexanol. The selectivity of the process is 96 to 98%.

Said process has a number of advantages over hydrogenation processes on copper and nickel catalysts. High selectivity (96-98%) can only be achieved with this catalyst system when using a dilute feedstock with a concentration of 2-ethylhexenal not more than 40-50 weight percent.

When the concentration of 2-ethylhexenal is increased to 70 to 90%, the selectivity of the process decreases to 86 to 88% due to the formation of hydrocarbons.

In addition, the double bonds in the feedstock are not hydrogenated on the zinc-chromium catalyst and it is therefore necessary to carry out the second hydrogenation step using a nickel or copper catalyst.

Therefore, when carrying out the process on a large scale, it is necessary to provide two reactors with an internal heat dissipation device, since a considerable amount of heat is generated in both the first and second hydrogenation stages.

For the hydrogenation of pure 2-ethylhexenal or dimeric product fraction, it was necessary to choose a catalyst which would provide a high yield of 2-ethylhexanol using a sufficiently concentrated feedstock with high space velocity and allow the hydrogenation of the aldehyde group and double bond in 2-ethylhexenal regarding the selective hydrogenation of hydroformylation by-products to valuable butyl alcohols.

The purpose of the invention is to increase the yield of the end product and to simplify the process technology.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the yield of the end product and to simplify the process technology in a process for the hydrogenation of pure 2-ethylhexenal or dimer product fraction by developing a new catalyst modification.

This object is achieved by the process of preparing 2-ethylhexanol by hydrogenating 2-ethylhexenal or a 2-ethylhexenal-containing product at elevated temperature in the presence of a zinc-chromium catalyst and separating the final hydrogenate product according to the invention. contains, in addition, copper oxide at a weight ratio of copper oxide: zinc oxide: tremendous oxide (12,3 to 54): (11,0 to 52,2):

(6 to 23.2) on the support and the process is carried out at a temperature of 200 to 290 ° C and a pressure of 10 to 30 MPa.

The catalytic hydrogenation is expediently carried out at temperatures of 230 DEG to 270 DEG C., since at temperatures below 230 DEG C. a reduction in the degree of conversion and selectivity of the process is observed due to the ongoing aldehyde condensation side reactions leading to the formation of a bubble product. At temperatures above 270 ° C, a decrease in selectivity is observed by the unsaturated aldehyde cleavage reactions leading to the formation of hydrocarbons.

Increasing the hydrogen pressure from atmospheric to 10 MPa increases the degree of conversion of aldehydes, esters, acetals, acids and unsaturated compounds. A further increase in pressure from 10 to 30 MPa causes an increase in the hydrogenation degree of only the unsaturated compounds and does not affect the degree of conversion of the other mentioned groups. Therefore, if it is important to obtain 2-ethylhexanol with a very high degree of purity according to the content of unsaturated compounds, the process is expediently carried out at pressures of approximately 30 MPa.

According to the invention, a cell of pure 2-ethylhexenal or products containing 2-ethylhexenal is used as the starting product, as the condensation products of a propylene hydroformylation catalyst, a fraction of dimeric products separated from the propylene hydroformylation catalyst and besides 2-ethylhexenal contains butylbutyrates, butyric acids .

Catalysts of the following composition are used.

Table 1

Sample of the catalyst C. Copper oxide Cu ₂ O ₃ Content (% by weight) Zinc oxide ZnO Chromium oxide Cr ₂ O ₃ 1 12.3 ± 1.5 52.2 ± 2 23.2 + 1.5 2 19.8 + 2 40.6 + 2 18.5 + 1.0 3 54 ± 3 11.5 + 1.5 14 ± 1.5 4 38 ± 1.5 30.5 ± 1.5 7 ± 1

Copper-zinc-chromium catalysts have never been used to hydrogenate aldehydes, especially unsaturated aldehydes. The use of catalysts containing copper, zinc and chromium in the proportions shown in the table has been shown to make it possible to obtain 2-ethylhexanol in a yield of 96 to 97%, regardless of the starting material composition. The process is carried out at 200 to 290 ° C, at a hydrogen pressure of 10-30 MPa, the space velocity of the feedstock inlet by 1.5 to 3 h ^- '. The acids contained in the feedstock are hydrogenated to 85 to 95%, esters to 80 to 90%, acetals to 80 to 90%. 2-Ethylhexanol of world-class quality is separated from the obtained hydrogenate by conventional rectification. The virtually complete (over 95%) hydrogenation of the double bonds makes it possible to carry out the process in a single reactor with a heat sink, thereby greatly simplifying the process diagram.

The concentration of 2-ethylhexenal in the raw material for the catalyst according to the invention is almost twice as high as for the aluminum-zinc-chromium catalyst, whereby the total space-time yield relative to 2-ethylhexanol increases considerably.

The increase in butyl alcohols by hydrogenation of the by-products is not less than that of the aluminum-zinc-chromium catalyst. The catalyst maintains its activity and selectivity for a period of time that is sufficient for implementation on a large technical scale.

Therefore, the addition of copper to the zinc and chromium catalysts results in a qualitatively new structure that combines the advantages of copper catalysts, double bond hydrogenation and high yield of end product and zinc and chromium catalysts, stability, high space velocity , by-product hydrogenation. Such an increase in the efficiency of the zinc-containing catalyst after the addition of copper oxide is very surprising, since it is known that exchangeable catalysts are unstable to the effect of hydroformylation by-products and rapidly lose their activity. In addition, the optimum hydrogenation temperature on the 150 to 170 ° C copper catalyst is low for the hydrogenation of hydroformylation by-products, namely acids, esters, acetals. However, raising the temperature to 230-270 ° C, which is optimal for the by-product hydrogenation, leads to complete decomposition of the cuprous catalyst.

The method according to the invention is illustrated by the following description of an embodiment with reference to the accompanying drawing, in which a technological diagram of the principle is shown. Giant. 1 shows a flow chart for the hydrogenation of 2-ethylhexenal, which is a process for preparing 2-ethylhexanol.

The hydrogenation is carried out in a continuous, high-pressure circulating apparatus with a reactor volume of 0.5 L (Fig. 1). The reactor is designed in the form of a tube 1000 mm high and 25 mm in diameter, which is equipped with a two-part electric heating. A thermocouple recess is located in the upper reactor lid. The temperature is measured at four points according to the height of the catalyst layer. Samples of the copper-zinc-chromium catalyst (composition shown in Table 1) were introduced as 5 x 5 mm tablets. The catalyst is activated in a stream of hydrogen at elevated temperature prior to operation.

The feedstock is fed from the tank 1 to the top of the reactor via a liquid pump. Hydrogen is supplied to tank 2 from the top of the reactor. In the reactor 1, hydrogenation of 2-ethylhexenal and hydroformylation by-products occurs at a temperature of 200 to 290 ° C and a hydrogen pressure of 20 to 30 MPa. The chemistry of the hydrogenation process can be illustrated by the following scheme:

1. Hydrogenation of 2-ethylhexenal to an unsaturated alcohol with simultaneous isomerization of the double bond by chain length

CH ₃ - (CH 2) 2 -CH = C -CH ₂ -OH c ₂ h ₅ .

CH ₃ - (CH ₂ ) 2 -CH = C-d + h ₂ - * ch ₃ -ch ₂ -ch = ch-ch -ch ₂ -oh

C2H5 Η C ₂ H ₅

OH ₃ -CH = CH-CH ₂ -CH-CH ₂ -OH

2-etylhexenol _{C2 H5} isomeric octenol

This very interesting fact of isomerization of unsaturated alcohol was first discovered by us in the hydrogenation test of 2-ethylhexenal on an aluminum-zinc-chromium catalyst and was also confirmed for the catalyst according to the invention.

2. Hydrogenation of isomeric octenols to 2-ethylhexanol:

isomeric octenols + H ₂ -> CH ₃ - (CH ₂ ) ₃ - 4 H-CH ₂ OH c ₂ h ₅

2-ethylhexanol

3. Isomerisation of unsaturated alcohol to saturated aldehyde:

c ₂ h ₅ ch ₃ - (ch ₂ ) ₂ -ch = c-ch ₂ oh;

= * CH ₃ - (CH ₂ ) ₃ -CH _{2 - 5} h ₅

2-ethylhexen-2-ol-1

2-ethylhexanal

4. Hydrogenation of 2-ethylhexanal to 2-ethylhexanol c ₂ h ₅

CH ₃ - (CH ₂ ) 3 -CH-CH ₂ - + H ₂ - K H ₃ - (CH ₂ ) 3 -CH-CH ₂ OH.

IH c ₂ h ₅

2-ethylhexanal. 2-ethylhexanol

5. Side reactions of cleavage of unsaturated aldehyde into hydrocarbons:

CH ₃ - (CH _{2) 2} -CH = CC ^ -> CH3- _{(CH2) 2} -CH = CH-CH 2 »CH3 + GO

I H »

C ₂ H ₅

2-ethylhexenal hepten- (3).

6, Hydrogenation of butyric acids to butyl alcohols:

y °

CH ₃ - (CH ₂ ) ₂ -C 4 _h + 2H ₂ -> - CH ₃ - (CH ₂ ) ₂ -CH ₂ OH + H ₂ 0 n-butyric acid n-butanol

CH ₃ -GH (CH ₃ ) -C 1-4 + 2H ₂ -> - CH ₃ -CH (CH ₃ ) -CH ₂ OH + H ₂ 0 isobutyric acid isobutanol

7. Hydrogenation of butyl esters to butyric acids:

a) CH ₃ - (CH ₂ ) ₂ -1-O (CH ₂ ) ₃ -CH ₃ + 2H ₂ -> 2 CH ₃ - (CH ₂ ) ₂ -CH ₂ OH n-butylbutyrate n-butanol

(b)

c) CH ₃ - (CH _{2) 2} - $ - O-CH ₂ -CH-CH ₃ + 2H ₂ -> CH ₃ - (CH _{2) 2} -CH ₂ OH CH ₃ isobutyl butyrate n-butanol + CH ₃ -CH (CH ₃ ) -CH ₂ OH isobutanol

O CH ₃

II I

CH ₃ -CH (CH ₃ ) -CO-CH ₂ -CH-CH 3 + 2H ₂ - »- 2CH ₃ -CH (CH ₃ ) -CH ₂ OH isobutylisobutyral isobutanol

8. Hydrogenation of butyraldehyde and butyl alcohol acetals:

, ^ 0C ₄ H 9 ^C 4 ^H & L + H ₂ + H ₂ 0-> 3C ₄ H9OH

OG ₄ Hg iso- or n-butylacetals iso- or n-butanol iso- or n-butyral

The reaction products and hydrogen enter through the cooler 6 into the high-pressure separator 2, where the gas and liquid phases are separated. From the upper part of the high-pressure separator, the gas pump 2 is returned via the oil separator 4, 10 to the upper part of the reactor. From the high-pressure separator 7, the reaction products enter the low-pressure separator 8. A portion of the gas is discharged from the high-pressure separator 2 through the gas meter 11 to the atmosphere to prevent the accumulation of inert impurities in the hydrogen circulating.

Therefore, the process according to the invention gives an increase in the yield of the end product, 2-ethylhexanol by approximately 10% compared to the known process, by reducing the hydrocarbon formation rate and simplifying the technology by carrying out the process in a single reactor with heat removal device instead of two-stage hydrogenation. Furthermore, in the process according to the invention, the energy consumption for heating the feedstock decreases since the optimum hydrogenation temperature on the copper-chromium catalyst is 230 to 270 ° C, which is 30 to 50 ° C lower than the optimum hydrogenation temperature on the aluminum- zinc-chrome.

In order to better understand the nature of the invention, examples of specific embodiments are given below.

He did

Hydrogenation is carried out according to the scheme shown in Figure 1. The raw material is a condensation product of n-butyraldehyde obtained by oxosynthesis in the presence of a cobalt salt (4550 g), comprising: 3,640 g of 2-ethylhexenal (80 wt%); 332.2 g of 2-ethylhexanal (7.3 wt%);

32.0 g of butyraldehyde and butanol acetals (0.7 wt%); 68.3 g of butyl alcohols (1.5 wt. 515); 332.2 g butylbutyrates (7.3 wt%); 13.6 g of 2-ethylhexanol (0.3 wt%); 68.3 g of butyric acids (1.5 wt.; 22.8 g water (0.5 wt.%); 40.1 g of unidentified products (0.9 wt.%). by pump 2 at a space velocity of 1.6 h ^- to the top of the reactor 2, not filled with a copper-zinc-chromium catalyst having the following composition: copper oxide (CU2O3) 12.3 and 1.5 wt.%, zinc oxide (ZnO) 52.2 ± 2.0 wt.% 515, chromium trioxide (CrgO ^) 23.2 ± 1.5 wt.% 515.

Hydrogen (supplied to the circulation and fresh from tank 2) also enters the top of the reactor 2 at a pressure of 20 MPa. · The hydrogen feed rate is 2.5 m3 / kg of feedstock. The reactor is maintained at a temperature of 230-240 ° C.

The reaction yielded 4,690 g of hydrogenate containing 3,934.5 g of 2-ethylhexanol (83.8 wt. 515); 361 g butanols (7.7 wt. 515); 42.2 g of 2-ethylhexanal (0.9 wt. 515); 6.1 g water (1.3 wt. 515); 121.9 g of hydrocarbons (2.6 wt. 515); 46.9 g butylbutyrates (1 wt. 0); 4.7 g acetals (0.1 wt%) and 121.9 g other products (2.6 wt%).

The degree of conversion of 2-ethylhexenal is over 99,515, process selectivity 97 S5. Rectification of the obtained hydrogenate separates 3,820 g of 2-ethylhexsinol, which contains 99.3% of the basic substance and 0.018% by weight of unsaturated compounds (for other values, see Table 2, Example 1) and 343 g of butyl alcohols.

The yield of 2-ethylhexanol obtained by rectification was 94,515 based on the aldehyde reacted.

Example 2

The process is carried out under the conditions described in Example 1 on a catalyst of the same type, but at a hydrogen pressure of 23 MPa, at a feed rate of 2 h @ -1. The raw material used was an alkaline condensation product of n-butyraldehyde oxosynthesis in an amount of 3,900 g containing 3,561 g of 2-ethylhexenal (91.3% by weight); 4.2.9 g of butanols (1.1 wt. 515); 62.4 g of butyraldehydes (1.6 wt. 515); 198.9 g of high-boiling products (5.1 wt. 515); 35.1 g water (0.9 wt.%).

Hydrogenation yielded 3 970 g of hydrogenate containing 3,474 g of 2-ethylhexanol

-209761

⁴⁷ (87.5 wt.%); 166.7 g of butanols (4.2 wt%); 107.2 g of high-boiling products (2.7 wt%); 107.2 hydrocarbons (2.7 wt%); 79.4 g water (2.0 wt%); 35.7 g 2-ethylhexanal (0.9 wt%).

The degree of conversion of 2-ethylhexenal is over 99% by weight, selectivity 97%. In 1 rectification of the obtained hydrogenate, 2-ethylhexanol containing 99.6% of the base substance is separated, 0.02% by weight. % unsaturated compounds. For other values, see Table 2, Example 2.

The yield of 2-ethylhexanol separated by rectification is 94% based on the aldehyde reacted.

Example 3

The process is carried out under the conditions described in Example 1, but using a copper-zinc-chromium catalyst of the following composition: CuO 19.8 ± 2.0 wt. %; Zinc oxide (ZnO) 40.6 ± 2.0 wt. %; chromium oxide (Cr 2 O 3) 18.5 ± 1.0 wt. %, A pressure of 28-30 MPa, a space velocity of the feedstock inlet by 2.3 h ^- ', a temperature of 245-255 ° C as a raw material using dimeric product fractions separated from the product .hydroformylace propylene having the following composition: 5.3 wt butanols . % butylbutyrates 6.1 wt. %, 2-ethyl-4-methylpentenal 0.9 wt. %, 2-ethylhexanal 8.0 wt. %, 2-ethylhexenal 70.5 wt. %, 2-ethyl-4-methylpentanol 0.2 wt. %, 2-ethylhexanol 0.5 wt. %, butyric acid 3.5 wt. % butyraldehydes and butyl alcohols 2.0 wt. %, unidentified products 2.7 wt. %, water 0.3 wt. %.

Hydrogenation gave the following composition: butanols 12.8 wt. % butylbutyrates 0.3 wt. %, 2-ethylhexanal 0.5 wt. %, 2-ethyl-4-methylpentenol 1.2 wt. %, octenols 0.3 wt. %, 2-ethylhexanol 76.1 wt. %, butyric acid 0.5 wt. 0.3 wt. %, unidentified products 4 wt. %, water 1.3 wt. %, hydrocarbons 2.7 wt. %.

The overall degree of conversion of aldehydes is 99.3%, the selectivity of 2-ethylhexanol formation is 97.5%. In the rectification of the hydrogenate, 2-ethylhexanol, containing 99% of the basic substance, 0.02 wt. % unsaturated compounds (Table 2, Example 3).

Example

The process is carried out under the conditions described in Example 1, but using a copper-zinc-chromium catalyst consisting of 54 ± 3 wt. % copper oxide (CuO); 11.5 and 1.5 wt. percent zinc oxide (ZnO); 14 ± 1.5 wt. % hydrogen bromide (Ο ^ Οβ), at a hydrogen pressure of 10 MPa, a temperature of 257 to 265 ° C and a feed rate of 1.5 h ^- '. The fraction of dimeric products whose composition is given in Example 3 is used as raw material.

Hydrogenation gave the following composition: butanols 12.3 wt. % butylbutyrates 0.7 wt. %, 2-ethylhexanal 0.6 wt. %, 2-ethyl-4-methylpentenal 0.2 wt. %, 2-ethylhexenal 0.1 wt. %, 2-ethyl-4-methylpentanol 1.0 wt. %, octenols 1.3 wt. %, 2-ethylhexanol 75.1 wt. %, butyric acid 0.8 wt. %, unidentified products 3.4 wt. %, hydrocarbons 2.7 wt. %, water 1.5 wt. %.

The degree of conversion of aldehydes is 99%, the selectivity of 2-ethylhexanol formation is 95%.

2-Ethylhexanol separated by rectification of the hydrogenate contains 98.5 wt. and 0.5 wt. % unsaturated compounds. To reduce the amount of unsaturated compounds to the amount given by the standard, the hydrogenate is fed into a reactor filled with nickel catalyst on diatomaceous earth.

Prehydrogenation is carried out at a temperature of 180 ° C, a space velocity of 1 h ^-1 and a hydrogen pressure of 28 to 30 MPa. Hydrogenation yields 2-ethylhexanol, which contains 99% of the parent substance and 0.01 wt. % unsaturated compounds (Table 2, Example 4). The hydrogenation on the copper-zinc-chromium catalyst at a pressure of 10 MPa does not guarantee the necessary degree of hydrogenation of the double bond in 2-ethylhexenal. In this case, in order to produce 2-ethylhexanol of the corresponding standard, it is necessary to add a second stage, pre-hydrogenation on copper or nickel catalysts.

Example 5

The process is carried out under the conditions described in Example 1 on a catalyst of the composition given in Example 1, but at a hydrogen pressure of 26 MPa, a temperature of 280 to 290 ° C, the feed rate of the feed of 1.5 h1. A fraction of dimeric products, the composition of which is given in Example 3, is used as the raw material. Hydrogenation yields the product of the following composition: butanols 12.6 wt. % butylbutyrates 0.5 wt. %, 2-ethylhexanal 0.5 wt. %, 2-ethyl-4-methylpentanol 1.2 wt. 56, 2-ethylhexanol 55.0 wt. 56, butyric acid 0.3 wt. 56, acetals 0.2 wt. %, unidentified products 6.4 wt. %, water 3.5 wt. 56, hydrocarbons 19.8 wt. 56.

The total degree of conversion of the aldehydes is 99.5 56, the selectivity to form 2-ethylhexanol 70 56. In the rectification of the hydrogenate, 2-ethylhexanol is recovered in a yield of 96 56 containing a base substance of 99 56 and unsaturated compounds of 0.01 wt. 56 (see Table 2, Example 6).

As can be seen from the above example, increasing the temperature to 280-290 ° C leads to a large increase in the side reaction by degrading 2-ethylhexenal to hydrocarbons, which has a disadvantageous effect on process selectivity.

Example 6 (Comparative example)

Example 6 illustrates an experiment carried out in a known manner on an aluminum-zinc-chromium catalyst at a temperature of 280 to 290 ° C, a pressure of 30 MPa in the first stage and a nickel catalyst on diatomaceous earth at a temperature of 180 ° C, a space velocity of 1 h ^- in the second stage. The fraction of dimeric products described in Example 3 serves as raw material.

Two-stage hydrogenation gave the following composition: butanols 12.6 wt. percent, butyl butyrates 1.6 wt. %, 2-ethylhexanal 1.0 wt. 56.2-Ethyl-4-methylpentanol 1.2 wt. 56, 2-ethylhexanal 1.0 wt. %, 2-ethyl-4-methylpentanol 1.2 wt. 56, octenols 0.2 wt. percent, 2-ethylhexanol 68.1 wt. 56, butyric acid 0.1 wt. %, acetyls 0.3 wt. 56, unidentified products 4.2 wt. %, water 2.2 wt. 56, hydrocarbons 8.5 wt. 56.

The degree of conversion of the aldehydes is 98.8 56, the selectivity of formation of 2-ethylhexanol is 87.8 56.

2-Ethylhexanol separated from the hydrogenate contains 99 56 base substance, 0.02 wt. % unsaturated compounds.

Therefore, the selectivity of the reaction of 2-ethylhexanol formation according to the known process is about 10 56 lower than in the process according to the invention (cf. example 3) at the same concentration of 2-ethylhexenal used, which is 70.5% by weight ·

Example 7

The process is carried out under the conditions described in Example 1, but at a hydrogen pressure of 30 MPa, a temperature of 200 ° C and a feed rate of 1.5 h ^-1 . A fraction of dimeric products having the composition described in Example 3 serves as raw material. Under hydrogenation under these conditions the degree of conversion of 2-ethylhexenal is 92%, the selectivity of formation of 2-ethylhexanol 91 56 due to the formation of high-boiling condensation products. After repeated hydrogenation of the separated 2-ethylhexanol on a nickel catalyst, a standard product is obtained. Therefore, lowering the temperature of the hydrogenation process to 200 ° C results in some selectivity reduction as well as incomplete hydrogenation of 2-ethylhexenal, which requires the addition of an additional degree of hydrogenation to achieve 2-ethylhexanol corresponding to the standard.

Example

The process is carried out under the conditions described in Example 1 but using a copper-chromium catalyst consisting of 38 to 1.5 wt. % copper oxide (CuO), 30.5 and 1.5 wt. % of zinc oxide (ZnO), 7 wt. at a temperature of 260 to 270 ° C, a hydrogen pressure of 26 MPa and a space feed rate of 3 h ^- 3. Pure 2-ethylhexenal in a quantity of 4,100 g containing 97 wt. % Of 2-ethylhexenal and 3 wt. % of high-boiling products.

The reaction yielded 4 180 g of hydrogenate of the following composition: 2-ethylhexanol 93.0 wt. percent, high-boiling products 2.8 wt. %, hydrocarbons 2.8 wt. %, 2-ethylhexanal 1 wt. %, water 0.4 wt. %.

The degree of conversion of 2-ethylhexenal is 99%, the selectivity of 2-ethylhexanol formation is 97%.

The yield of 2-ethylhexanol separated by rectification is 94.5% based on the reacted aldehyde, the base substance content in the product is 99.7%, the unsaturated compounds content 0.01% (see Table 2, Example 8).

Therefore, it is possible to carry out the process under optimal conditions and in one step, without additional pre-hydrogenation.

Table2

Technological state of quality of 2-ethylhexanol obtained by the process according to the invention in comparison with the values of various companies

Quality values set by the standard Comparative values of RGW recommendations for standardization Japan firm Mitsubishi 2-ethylhexanol obtained according to example no. 1 2 3 4 5 8 1. Platinum-cobalt color number, maximum 10 10 10 10 10 10 10 10 2. Density, ²⁰ 3 4, g / cm ^J 0.831-0.836 0,835 0,834 0,835 0,834 0,834 0,83 ' 3. Content of basic substance of matter. %, at least 98.0 99.0 99.3 99.6 99.0 99.0 99.0 99.7 4. Aldehyde content, mass. %, maximum 0.1 miss miss miss miss miss errors: 5. Content of unsaturated compounds, calculated on 2-ethylhexenal, wt. %, maximum 0.1 0.1 0.018 0.02 0.02 0.01 0.01 0.01 6. Acid value, mg KOH / g, maximum 0.14 0.23 0.02 0.02 0.02 0.02 0.02 0.01 7. Boiling range, ° C 182-186 183 až 184 183 až 184 183 až 184 183 až 184 183 až 184 183 až 184

Claims (2)

SUBJECT OF THE INVENTION A process for the preparation of 2-ethylhexanol by catalytic hydrogenation of 2-ethylhexenal or a product of 2-ethylhexenal containing at elevated temperature and elevated pressure in the presence of a zinc-containing and catalyst-containing catalyst and separating the final product from the hydrogenate. copper oxide at a weight ratio of copper oxide: zinc oxide: chromium oxide (12.3 to 54): (11.0 to 52.2): (6 to 23.2) on the support and the process is carried out at a temperature of 200 to 290 ° C and a pressure of 10 to 30 MPa. 2. The process according to claim 1, wherein the process is carried out at a temperature of 230 to 270 [deg.] C.