DE19540295A1 - Process for the production of short chain alkyl sulfates - Google Patents

Abstract

The invention concerns a process for preparing short-chain alkyl sulphates in which alcohols of formula (I), R<1>OH, in which R<1> stands for a linear or branched, saturated or unsaturated alkyl group with between 6 and 12 carbon atoms, are sulphated with a mixture of SO3 and inert gas in a stirrer vessel cascade arrangement comprising at least two stirrer vessels which can be supplied with gas independently of each other. The alcohols are then neutralized with aqueous bases. Sulphation is carried out in the presence of acid anionic surfactants of formula (II), R<1>OSO3H, in which R<1> has the above meaning. In this way, high yields of high-quality alkyl sulphates are obtained and the risk of explosive alcohol mixtures igniting in the exhaust air purified by electrostatic filters is simultaneously prevented.

Description

The invention relates to a method for producing short-chain Alkyl sulfates by sulfating fatty alcohols with SO₃.

State of the art

For the production of alkyl sulfates, which are often called fatty alcohol sulfates are referred to, primary, linear or branched alcohols out. These are usually mixed with sulfuric acid, oleum, chlorosulfonic acid and mainly implemented with gaseous SO₃. The resulting Sulfuric acid half-esters are then with aqueous bases such. B. Sodium hydroxide solution, ammonia or alkanolamines neutralized (J. Falbe (ed.) "Surfactants in consumer products", Springer Verlag, Berlin, 1987, p. 67 or J. Falbe, U. Hasserodt, "Catalysts, Surfactants and Mineral Oil Additives", Thieme Verlag, Stuttgart, 1978, p. 132). Sulphation is on an industrial scale predominantly with sulfur trioxide / air mixtures in falling film reactors carried out, but the use of short-chain fatty alcohols with serious technical problems are:

Usually the sulfation with an average SO₃ content of 3 vol .-% carried out in air. The resulting exhaust air contains Fat vapors and aerosols and SO₂ / SO₃ at a temperature of 50 to 60 ° C. When using short-chain fatty alcohols with flash points around 75 ° C it can  therefore in the e-filters connected to the ignition for cleaning the exhaust air for ignition of these ignitable mixtures come.

The object of the present invention was a technical easy to carry out, safe process for the production of short-chain Developing alkyl sulfates.

Description of the invention

The invention accordingly relates to a method for the production short-chain alkyl sulfates, in which alcohols of the formula (I)

R1 OH (I)

in the R1 for a linear or branched, saturated or unsaturated Alkyl radical having 6 to 12 carbon atoms is in a cascade of stirred tanks consisting of at least two stirred kettles, which are gassed independently can be sulfated with a SO₃ / inert gas mixture and then with neutralized aqueous bases, wherein the sulfation in the presence of acidic anionic surfactants of the formula (II)

R¹OSO₃H (II)

carries out in which R¹ has the meaning given above.

It has now surprisingly been found that the Process according to the invention in high yields, lower alkyl sulfates are good Preserves quality, and the cleaning of the exhaust air by means of electrostatic filters runs smoothly because the content of fatty alcohols in the exhaust air is clear is reduced and ignitable mixtures can no longer form.  

Fatty alcohols

Among fatty alcohols in the context of the present invention are primary to understand aliphatic alcohols of the formula (I)

R1 OH (I)

in the R1 for a saturated or unsaturated, linear or branched Hydrocarbon radical having 6 to 22 carbon atoms.

Typical examples are capronic alcohol, caprylic alcohol, 2-ethylhexyl alcohol, Capric alcohol, lauryl alcohol, isotridecyl alcohol, myristyl alcohol, cetyl alcohol, Palmoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, Elaidyl alcohol, petroselinyl alcohol, linolyl alcohol, linolenyl alcohol, Elaeo stearyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol and brassidyl alcohol and their technical mixtures, the z. B. at the High pressure hydrogenation of technical methyl esters based on fats and Oils or aldehydes from Roelen's oxo synthesis and as a monomer fraction in the dimerization of unsaturated fatty alcohols. Linear and / or are particularly preferred for the purposes of the present invention branched alcohols with 6 to 12 carbon atoms. In a preferred one Embodiment is sulfated 2-ethylhexyl alcohol.

method

The sulfation is preferably carried out continuously in a cascade of stirred tanks consisting of at least two stirred kettles. The sulfation takes place in the presence of acidic anionic surfactants of the formula (II)

R¹OSO₃H (II)

in which R¹ has the same meaning as given above. Preferably you lay First, the alcohol to be sulfated in each kettle and directs the SO₃ / inert gas mixture, preferably with air as the inert gas, so that first one  discontinuous sulfation takes place in the individual boilers. The template is usually 20 to 50 wt .-% per in the continuous Operation hourly amount of alcohol to be fed. The sulfation is in usually carried out at a temperature in the range of 30 to 50 ° C an acid number of 240 to 250 has been reached. The SO₃ / inert used gas mixture can 5 to 15 vol .-%, preferably 6 to 10 vol .-% SO₃ in Contain air; despite this high concentration, there is predominantly one Sulfation of alcohols and not for oxidation. Then will continuously fed alcohol into the first kettle and as it passed through the Cascade in each boiler by gassing with SO₃ / inert gas mixture, preferably again with a content of 6 to 10 vol .-% SO₃, sulfated. in the The connection to the last boiler is neutralized as quickly as possible.

In a particularly preferred embodiment, the sulfation is carried out in a stirred tank cascade consisting of two reactors. To 50 to 150 kg of alcohol are preferably placed in each reactor and discontinuously sulfated. The continuous sulfation usually takes place at a temperature in the range of 30 to 60, preferably 35 to 45 ° C. Of the Alcohol is fed into the first reactor with a mass flow of 180 to 230 kg / h initiated. The SO₃ / inert gas mixture is in the preferred embodiment with a mass flow of 40 to 60 kg sulfur / h evenly on both Reactors distributed. Air is preferably used as the inert gas. Right in After sulfation, neutralization is usually carried out at 40 to 60% by weight aqueous alkali, alkaline earth or ammonium hydroxide solution.

Neutralization with 50% by weight aqueous is preferred Sodium hydroxide solution performed.

The exhaust gases are first passed through an electrostatic filter and then subjected to an alkaline treatment.

In a particularly preferred embodiment, the exhaust gases in the sulfation of the short-chain alcohols, together with those those in the sulfation of longer-chain alcohols or alkylbenzenes in one  second system arise, passed on an electrostatic filter. By the Mixing the exhaust gases results in the short-chain dilution highly flammable compounds in the exhaust air and thus the Risk of ignition reduced.

The alkyl sulfates obtained can then with butyl glycol or polyol polyethers can be compounded.

Industrial applicability

Alkyl sulfates are widely used as surfactants, the short chain Products can be used for special applications, e.g. B. for production of textile auxiliaries.

Examples Production of 2-ethylhexyl sulfate

In a sulfonation reactor consisting of two cascaded Mixing kettles, each with separate SO₃ fumigation, were initially in both Boilers 100 kg (0.78 kMol) of 2-ethylhexanol and placed at 35 to 40 ° C. discontinuously reacted with sulfur trioxide until an acid number of 240 to 250 was reached. Then with a mass flow of 230 kg / h 2-ethylhexanol is introduced into the first kettle and the solution continuously sulfated, the SO₃ / inert gas mixture with a mass flow of 55 kg / h Sulfur was evenly distributed across both reactors. Air became the inert gas used, the dilution was 6 vol .-% SO₃ in air. After sulfation the crude product was continuously in a 35 wt .-% aqueous solution of Sodium hydroxide introduced and neutralized. The neutralized product was adjusted to a pH of 8.5.

Claims (7)

1. A process for the preparation of short-chain alkyl sulfates, in which alcohols of the formula (I) R¹OH (I) in which R¹ represents a linear or branched, saturated or unsaturated alkyl radical having 6 to 12 carbon atoms, in a stirred tank cascade consisting of at least two stirred tanks, which can be gassed independently, sulfated with a SO₃ / inert gas mixture and then neutralized with aqueous bases, characterized in that the sulfation is carried out in the presence of acidic anionic surfactants of the formula (II) R¹OSO₃H (II), where R¹ has the meaning given above . 2. The method according to claim 1, characterized in that one Carries out sulfation with an SO₃ content of 5 to 15 vol .-% in air. 3. Process according to claims 1 and 2, characterized in that the sulfation continuously in a stirred tank cascade consisting of two Performs stirring kettles. 4. Process according to claims 1 to 3, characterized in that continuous sulfation with a mass flow of alcohol from 180 to Performs 230 kg / h and the SO₃ / inert gas mixture with one Mass flow of 40 to 60 kg sulfur / h evenly on both reactors distributed.   5. The method according to claims 1 to 4, characterized in that the Sulfation is carried out at a temperature between 30 and 60 ° C. 6. Process according to claims 1 to 5, characterized in that for continuous neutralization of aqueous solutions of alkali, alkaline earth or anunonium hydroxide. 7. The method according to claims 1 to 6, characterized in that the exhaust air generated in this process, together with that in the Sulfation of longer chain alcohols or alkylbenzenes in a second The resulting exhaust air is directed to an electrostatic filter.