EP0475968A1

EP0475968A1 - Process for preparing tenside mixtures based on ether sulphonates and use of said tenside mixtures

Info

Publication number: EP0475968A1
Application number: EP90908224A
Authority: EP
Inventors: Willi WÜST; Rainer Eskuchen; Bernd Richter
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1989-06-05
Filing date: 1990-05-28
Publication date: 1992-03-25
Also published as: CA2058761A1; WO1990015050A1; DE3918265A1; US5318709A

Abstract

Procédé pour fabriquer des mélanges tensio-actifs dont des alkyléthersulfonates, ou leurs sels (éthersulfonates), sont le constituant principal et qui sont utiles en particulier dans le cadre de l'exploitation tertiaire du pétrole, en faisant réagir des alkyléthersulfates avec une solution aqueuse de sulfite alcalin à une température comprise entre 160 et 220°C. Pour obtenir des mélanges des éthersulfonates au moins en grande partie exempts de sels de sulfate à partir d'alcools alcoxylés d'origine naturelle et/ou synthétique, la réaction se fait avec des quantités au plus à peu près égales des alcools alcoxylés, dans un milieu aqueux, à un pH légèrement alcalin, avec un excédent stoechiométrique de sulfate alcalin; suit, le cas échéant, une réaction ultérieure dans les conditions précitées; on extrait ensuite le mélange tensio-actif ainsi obtenu avec des alcools au moins en grande partie solubles dans l'eau, à une température inférieure mais toujours élevée. L'invention porte en outre sur l'utilisation pour l'extraction tertiaire du pétrole de ces mélanges tensio-actifs, en particulier sous forme de mélanges avec de l'alcool résiduaire provenant de la phase d'extraction.Process for manufacturing surfactant mixtures of which alkylethersulfonates, or their salts (ethersulfonates), are the main constituent and which are useful in particular in the context of tertiary petroleum exploitation, by reacting alkylethersulfates with an aqueous solution of alkali sulphite at a temperature between 160 and 220 ° C. To obtain mixtures of ethersulfonates at least largely free of sulfate salts from alkoxylated alcohols of natural and / or synthetic origin, the reaction is carried out with at most approximately equal amounts of the alkoxylated alcohols, in a aqueous medium, slightly alkaline pH, with a stoichiometric excess of alkaline sulfate; follows, where appropriate, a subsequent reaction under the aforementioned conditions; then extracting the surfactant mixture thus obtained with alcohols at least largely soluble in water, at a lower temperature but still high. The invention further relates to the use for tertiary petroleum extraction of these surfactant mixtures, in particular in the form of mixtures with residual alcohol from the extraction phase.

Description

"Process for the preparation of surfactant mixtures based on ether sulfonate and their use"

The invention relates to a new process for the production of surfactants and surfactant mixtures based on fatty alcohol ether sulfonates, which leads to the economical extraction of this class of surfactants, which is of great technical interest.

Tertiary oil production, in which the residual oil quantities retained in the deposit by viscosity and capillary effects in the pore space are to be made at least partially extractable, is becoming increasingly important today. A whole series of process types have been proposed for this, for example polymer flooding, alkali flooding, thermal processes or solution flooding.

The invention relates to the type of process which has become known as surfactant flooding. While the oil is present in the fresh oil reservoir as a continuous phase in the Cesteins pore space, with increasing primary and secondary production the oil phase disintegrates into individual discrete drops, which are retained in narrow pores due to the large interfacial tension. To overcome the capillary forces, either extremely high pressures would be required or the interfacial tension between water and oil would have to be greatly reduced with suitable surfactants. In individual cases, this decrease depends very much on the reservoir temperature, the salinity of the reservoir water and the composition of the oil. Only by adapting the respective surfactant mixture and under the conditions of the extreme limit The desired so-called middle-phase microemulsion is formed and the middle third phase lies between the heavier salt water phase and the lighter oil phase. Your training is of crucial importance for residual oil removal.

Various surfactant requirements are placed on suitable surfactants, which go beyond the ability to extremely reduce the interfacial tension. For example, they must not form precipitation in the flood or formation water, otherwise there is a risk of irreversible blockage in the reservoir. They should be adsorbed on the rock as little as possible. They have to be stable under deposit conditions, whereby the distance between the injection probe and the conveyor probe is 50 to 300 m and flood speeds of approx. 0.3 m / d periods of stability are of the order of 1 to 3 years.

In particular, ether sulfates, ether carboxylates, ether sulfates and ether phosphates have been proposed as surfactants for use in highly saline reservoir waters. Ether sulfates and ether phosphates are technically easily accessible types of surfactants, but are not hydrolytically stable. The ether sulfonates, and here in particular the alkyl ether sulfonates, have shown particularly interesting properties in screening tests. They combine good electrolyte compatibility with high stability against hydrolysis phenomena at high temperatures. In particular, however, they also show the occurrence of the desired three-phase states in oil / water / surfactant systems with a broad mid-phase microemulsion range and a high reduction in interfacial tension. Mixing them with other surfactants and / or so-called cosolvents opens up technically interesting possibilities in the context of tertiary oil production. Numerous syntheses have been proposed for the preparation of ether sulfonates, cf. the publication "fatty alcohol ether sulfonates for tertiary oil production", Fette-Seifen-Anstrichmittel, 1985, 382 - 385 and the literature cited therein. The invention is based on the object of providing a technologically simple process which enables the economical production of this interesting class of surfactants and, in particular as a direct reaction product, provides a surfactant-containing multicomponent mixture which as such has valuable properties for the stated Intended use. This primary surfactant mixture consists of the alkyl ether sulfonates mentioned as the main component aimed for and also contains nonionic fatty alcohol ethers of the type on which the ether sulfonates are based and optionally so-called cosolvents based on synthetic and / or natural alcohols.

The invention accordingly relates in a first embodiment to a process for the preparation of surfactant mixtures based on alkyl ether sulfonic acids or. their salts (ether sulfonates) as the main constituent, which can be used in particular in the context of tertiary petroleum production and are obtained by reacting alkyl ether sulfates with an aqueous alkali sulfite solution at temperatures of 160 to 220 ° C, this method being characterized in that for the preparation of at least largely sulfate salt-free mixtures of the ether sulfonates based on alkoxylated alcohols of natural and / or synthetic origin with at most approximately equal amounts of the alkoxylated alcohols carrying out the reaction in the aqueous medium at a weakly alkaline pH with a stoichiometric excess of alkali sulfite, if desired with the stated Reaction conditions can react and then with lowered, but still increased Temperatures the surfactant mixture formed extracted with at least largely water-insoluble alcohols.

In a further embodiment, the invention relates to the surfactant mixtures produced by this process, in particular in a mixture with residual alcohol from the extraction stage for the tertiary petroleum production.

The alkoxylation of alcohols of natural and / or synthetic origin, in particular of the fatty alcohol range with ethylene oxide and / or propylene oxide, is known to lead to correspondingly alkoxylated fatty alcohol compounds with nonionic surfactant character. Their terminal esterification with sulfuric acid to form the corresponding sulfate salts provides the fatty alcohol sulfates.

In the type of process concerned according to the invention, the alkyl ether sulfates are converted to alkyl ether sulfonate in the context of a nucleophilic substitution by means of sulfite, which are referred to below simply as "ether sulfonates". The associated reaction equation for the desired main reaction is given as

R'-O-SO ₃ Na + a ₂ SO ₃ >R'-SO ^ a + a ₂ ≤O ₄ (I).

In this equation, R ¹ corresponds to the alkoxylated alcohol residue.

The nucleophilic substitution affected here requires comparatively high temperatures and correspondingly high pressures and is nevertheless still a relatively slow reaction. As a result of this reaction, which is carried out in an aqueous medium, alkoxylated alcohol is obtained in not insignificant amounts as a saponification product with a typically non-surfactant character. At the same time is for the invention Purpose of the surfactants formed the following additional consideration with decision-relevant:

The sodium sulfate obtained as a reaction by-product in the aqueous phase must have been almost completely removed from the surfactant mixture ultimately to be removed. If, in practical use, substantial amounts of the sulfate anion were introduced into the petroleum deposit via the surfactant components formed in this way, the capillary system would quickly become clogged due to the in situ formation of alkaline earth metal sulfates. The type of reaction affected here to form the ether sulfonates thus brings suitable surfactants or. Surfactant mixtures pose a much more complex problem than it initially appears. The situation is further complicated by the fact that the reaction of the ether sulfates with sodium sulfite in aqueous solution is not problem-free. The reaction mixtures tend to gel, are then difficult to handle and, at the high reaction temperatures required, quickly form crust-like deposits on the inside walls of the reactor, which require an interruption in the reaction and cleaning of the interior of the reactor.

The teaching according to the invention in its following representation comprises two sample areas, which are solved by the measures chosen according to the invention so that the industrial production of surfactants or. Surfactant mixtures of the type concerned here is made possible.

The first problem area relates to the sum of the measures, the observance of which leads to the optimization of the nucleophilic substitution previously represented in the formula. The second problem area relates to the separation and recovery of the product of value formed from the reaction mixture. The following applies in detail here: The nucleophilic substitution

The preferred starting materials on the side of the alkyl ether sulfates are corresponding components with at least predominantly 6 to 18 carbon atoms and in particular 10 to 16 carbon atoms in the alkyl radical of the alcohol. Alcohols or. Alcohol mixtures with an average of 12 to 14 carbon atoms in the molecule serve as the main body of the surfactant class concerned here. Suitable alcohols are of both natural and synthetic origin, and mixtures of such alcohols can also serve as the basis for the compounds concerned here. A suitable feed material for the production of the alkyl ether sulfates not naturally claimed in the context of the invention are e.g. B. Corresponding coconut and / or palm kernel fatty alcohols which have been obtained by hydrogenating reduction of the fatty acids or fatty acid methyl esters. The basic alcohols forming alkyl ether sulfates are preferably saturated compounds, but can, if desired, also be olefinically unsaturated.

The alcohols used primarily in the preparation of the alkyl ether sulfates are alkoxylated, ethylene oxide and / or ^ ropylene oxide being used in particular in a manner known per se for the alkoxylation. In the preferred embodiment, the corresponding fatty alcohol alkoxylates have an average degree of alkoxylation above 1 and preferably not above 10, whereby particularly suitable average degrees of alkoxylation can be in the range from about 2 to 8. The HLB values of the non-surfactant components formed are determined in a known manner by the length of the C chain distribution and the degree of alkoxylation. The alkyl ether sulfates used as the essential reactant in the process according to the invention are formed by esterification of the alkyl ethoxylates with sulfuric acid, the corresponding sodium salts being generally added to the reaction according to the invention in aqueous solution. Here has shown that 10 to 40 wt. -% aqueous solutions, in particular 15 to 25 wt. % aqueous solutions of the ether sulfates can be used with particular advantage. According to the invention, however, solutions of a much higher concentration, for. B. about 70% by weight solutions of the ether sulfates are used. The other reactant for carrying out the nucleophilic substitution reaction is sodium sulfite, which is likewise placed in an aqueous solution. Sodium sulfite can be used as such, but according to the invention it is also possible, in particular to save costs, to use the less expensive sodium disulfite (Na ₂ S_0 ₅ ). As is known, Na_S_0 ₅ forms the following equilibrium in aqueous solution in the presence of a base - preferably sodium hydroxide solution according to the invention:

Na ₂ S ₂ 0 ₅ + ₂ Na ₂ S0 ₃ + 2H ₂ 0 (II).

The invention provides for the alkali sulfite to be used in a stoichiometric excess in the reaction. A preferred upper limit for this stoichiometric excess is a molar ratio of sulfite / ether sulfate of about 5, a further preferred lower limit being about 1.5. Numerical values of the stoichiometric excess of sulfite in the range from about 1.5 to 3 moles, based on moles of alkyl ether sulfate, are particularly suitable.

Another preferred embodiment of the invention relates to the predetermined direction of addition of the reactant solutions to be reacted with one another. Here, in its more important embodiment, the invention presents the aqueous alkali sulfite solution under reaction conditions when working batchwise in a batch process. The aqueous alkyl ether sulfate solution is fed into this sulfite solution, expediently with simultaneous mixing. In particular, the addition of the alkyl ether sulfate solution becomes slow batchwise or preferably continuously doses that a not inconsiderable portion of the total reaction period selected is required for this feed of the alkyl ether sulfate requirement. In the preferred embodiment, at least about 20% of the total reaction period required is used for this addition.

In a further preferred embodiment, the concentration of the reactants is restricted such that surfactant contents in the resulting aqueous reaction mixture are not adjusted above about 40% by weight and in particular up to about 25% by weight. The reaction is carried out in the weakly alkaline range, in particular at pH values of about 7.5 to 10, sodium-alkaline conditions being particularly preferred here.

By coordinating the reaction parameters with one another, the implementation can be optimized in the direction of the desired nucleophilic substitution reaction with simultaneous restriction or minimization of the proportion of alcohol ethoxylate, preferably to values below 50% by weight and in particular at most about 30 to 40% by weight. %, based on total surfactant content. The particularly preferred process parameters are the following:

Reaction temperatures in the range from about 180 to 200 ° C., pH values of the reaction mixture in the range from about 8 to 9 and molar ratios of sulfite / alkyl ether sulfate in the range from 1.5 to 2 at pressures up to about 20 bar, preferably under autogenous pressure.

The surfactant mixtures formed can have an alkyl ether sulfonate content of at least 60% by weight and preferably at least about 70% by weight. The described choice of the delayed addition of the alkyl ether sulfate reaction component successfully prevents the undesired gelation of the reaction mixture and thus prevents the buildup of the inner wall of the reactor. The response times are usually about 2 to 6 hours, preferably at least about 3 hours per reaction batch.

The isolation of the surfactant mixture formed

The ether sulfonates, but preferably the resulting mixture of ether sulfonates and alcohol alkoxylates, must be separated from the aqueous salt solution in a subsequent step. As already stated, particular care must be taken to ensure that the salts dissolved in the aqueous phase do not, or at best only in small amounts, pass into the surfactant mixture to be separated off.

The teaching of the invention uses a working measure for this separation step, the usability and effectiveness of which in the form described below could not have been foreseen.

Under carefully selected working conditions, in particular the working temperature, it is possible to achieve an almost quantitative separation of the aqueous salt phase and the surfactant phase formed by extraction with water-insoluble alcohols. Suitable are at least largely water-insoluble alcohols of synthetic and / or natural origin with preferably up to 14 * C atoms, in particular with 4 to 8 C atoms. Particularly suitable extraction agents here are amyl alcohols and / or hexanols of synthetic and / or natural origin, which can be straight-chain and / or branched. The following applies again in detail:

The extraction with the alcohol phase is carried out in one or more stages at temperatures, preferably in the range from about 50 to 100 ° C. and in particular in the range from about 80 to 90 ° C. Suitable mixing ratios of the reaction mixture to be extracted from the extractant are preferably not more than about 30% by weight and in particular in the range from about 3.5 to 15% by weight. The extraction can be carried out batch-wise, semi-continuously or continuously. Simply mixing the phases to be brought into contact is sufficient for effective extraction.

After completion of the extraction, the aqueous and alcoholic phases are generally separated from one another smoothly, the alcoholic phase is drawn off and expediently fed to a further workup.

In the course of this workup, at least portions of the alcohol used as extractant are preferably recovered, for example by distillation, and separated from the surfactant mixture formed. The recovered alcohol can be reused in the next extraction stage.

For the purposes of the invention, however, it is of particular importance that lower alcohols of the type used here as extraction agents and in particular the particularly preferred alcohols of the C ₅ , g range in the context of tertiary petroleum production as so-called co- Solvents are used in practice. According to the invention, it is accordingly not necessary at all to carry out the alcohol removal except for very low residual alcohol contents in the surfactant mixture. The surfactant / alcohol multicomponent mixture, which still has considerable alcohol fractions, can be used directly for the intended purpose. For example, residual alcohol contents in the separated reaction product are preferred in the range up to about 100% by weight, preferably in the range from 15 to 35% by weight, based in each case on TensI-dge isch. The content of disruptive sulfate ions in the reaction mixture obtained in this way is usually below 0.5% by weight, expediently below 0.2% by weight and can also be kept at a maximum of about 0.1% by weight become. Such low levels of sulfate ions in the surfactant mixture are tolerable for the intended purpose.

Examples

I. Starting materials and reaction conditions for three typical pilot plant experiments (reaction)

Feed Experiment 1 Experiment 2 Experiment 3

Texapon K 14 S; 25% (kg) 310.5 414.2

(C ₁₂ / C ₁₄ ether sulfate; 3.6 EO)

LS 8 sulfate, 25% (kg) - - 393

(C ₁₂ / C _lit ether sulfate; 8 EO)

Sodium sulfite (kg) 33.9 60.0 59

Water (kg) 86.9 101.4 249.8

Surfactant content (%) 18 18 14

mol SO_

mol ether sulfate 1.5 2.0 3.0

pH 9 9 9

Reaction temperature (° C) 210 200 180

Dosing time (h) 1 1 1

reaction time

(incl. dosing time) (h) 5 4 8

Yield ether sulfonate (%) 72.3 76.2 78.9 II. Input materials and test parameters for extraction

Trial 1 Trial 2 Trial 3

Feed RG * Vers. 1 RG Vers. 2 RG Vers. 3

Extractant

Hexanol + - +

Pentanol (I somere mixture) - + -

Batch process - + + continuous + - -

Feed

Extractant 3, 5 10 2, 3

* Reaction mixture

I I. Experimental setup

1 . reaction

The syntheses of the ether sulfonates based on the corresponding

3 ether sulfates were carried out in a 1 m pressure reactor with the following technical data:

Stirred reactor, 1 m ³ , material 1.4539

Permissible operating pressure: 30 bar

In addition to the heating-cooling area over the reactor wall, the

Reactor equipped with an internal heating coil.

4-stage slotted Internig agitator with trapezoidal stirrer as

Final organ. Piston metering pump for metering the ether sulfate solution.

2. extraction

3 batch: 1 m pressure reactor continuous: 3 m extraction lifting column;

Inner diameter 5 cm, 50 sieve trays; about

Double jacket heated

IV. Carrying out the experiment

1 . reaction

The sodium sulfate solution adjusted to the desired pH with sulfuric acid is placed in the reactor, heated to the reaction temperature and the ether sulfate solution, with the pH adjusted accordingly, is metered in by means of the piston pump (see metering time). After the reaction has ended (see reaction time), the reaction mixture is cooled to a temperature below 100 ° C. and fed to the extractive workup.

2. extraction

The extraction experiments were carried out with n-hexanol and pentanol (mixture of isomers). Both alcohols should be evaluated equally in terms of their properties as extractants and in the extraction result.

The extraction tests were carried out at 80 ° C., since the depletion of the valuable product in the aqueous phase is favored by elevated temperatures. In a single-stage mode of operation, ether sulfonate in the raffinate is reduced to less than 1% by weight, so that under certain circumstances a multi-stage extraction can be dispensed with. By encore of salts such as NaCl, Na 2 SO 4 or ammonium acetate, the coalescence behavior of the system can be improved so that the phase separation times are shortened.

Trial 1

The reaction mixture from experiment 1 was worked up continuously in a 3 m extraction lifting column with an inner diameter of 5 cm and 50 sieve trays. The throughput was 18 l / h, the feed: extracting agent ratio 3.5 and the temperature 80 ° C. N-hexanol was used as the extractant. An extract with the following composition was obtained:

Ether sulfonate: 19%

Water: 21%

Hexanol: 53%

Impurities: * 7%

* Ether sulfate, non-ionic surfactants, Na_SO "

Trial 2

The reaction mixture from experiment 2 was worked up discontinuously in a one-step extraction with pentanol (isomer mixture). For this purpose, feed and extractant were placed in a ratio of 10: 1 in a stirred reactor, heated to 80 ° C. and stirred intensively for 0.5 hours (large phase interface). After phase separation, the two phases were drained separately. An extract with the following composition was obtained: Ether sulfonate: 29%

Water: 40%

Pentanol: 22%

Impurities: * 9%

* Ether sulfate, non-ionic surfactants, Na_SO _ü

Trial 3

The reaction mixture from experiment 3 was worked up discontinuously in a one-stage extraction with n-hexanol. For this purpose, feed and extractant were placed in a ratio of 2.3: 1 together with 2% NaCl in a stirred reactor, heated to 80 ° C. and stirred intensively for 0.5 hours (large phase interface). After phase separation, the two phases were drained separately and the organic phase was washed with 7% water and 1% NaCl.

An extract of the following composition was obtained:

LS8 sulfate: 1.2%

LS8 sulfonate: 13.6% non-ionic surfactants 4.4%

Claims

P a t e n t a n s r u c h e

Process for the preparation of surfactant mixtures based on alkyl ether sulfonic acids or. their salts (ether sulfates) as the main constituent, which can be used in particular in the context of tertiary petroleum production and can be obtained by reacting alkyl ether sulfates with an aqueous alkali sulfite solution at temperatures of 160 to 220 ° C, characterized in that at least largely Sulfate salt-free mixtures of the ether sulfonates based on alkoxylated alcohols of natural and / or synthetic origin with a maximum of about the same amounts of the alkoxylated alcohols carry out the reaction in an aqueous medium at a weakly alkaline pH with a stoichiometric excess of alkali sulfite, if desired at the given conversion reaction conditions and then extracted the surfactant mixture formed with at least largely water-insoluble alcohols at reduced but still elevated temperatures.

Process according to Claim 1, characterized in that alkyl ether sulfates with at least predominantly 6 to 18 carbon atoms, in particular with 12 to 14 carbon atoms in the alkyl radical, are used which have an average degree of alkoxylation above 1 and preferably not above 10, in particular in the range of approximately Have 2 to 8. 3. Process according to Claims 1 and 2, characterized in that the aqueous sulfite solution with a molar ratio of sulfite / alkyl ether sulfate to about 5, preferably in the range from about 1.5 to 3, and the aqueous alkyl ether sulfate solution are advantageously introduced into the sulfite solution simultaneous mixing and in such a time-delayed addition that at least about 20% of the total reaction time required is used for the addition of the alkyl ether sulfate reactant.

4. Process according to Claims 1 to 3, characterized in that the reaction in the pH range from 7.5 to 10, preferably using basic alkali metal compounds, in particular corresponding sodium compounds for adjusting the pH and at pressures up to about 20 bar is carried out.

5. The method according to claims 1 to 4, characterized gekennzeich¬ net that by matching the reaction parameters to each other and in particular by working in the temperature range from 180 to 200 ° C at pH values of the reaction mixture in the range from 8 to 9 and a molar ratio of sulfite / alkyl ether sulfate in the range from 1.5 to 2, preferably under autogenous pressure, in the surfactant mixture formed, an alkyl ether sulfonate content of at least 60% by weight. %, preferably at least 70% by weight, based on the surfactant mixture formed.

6. The method according to claims 1 to 5, characterized gekennzeich¬ net that the extraction of the surfactant mixture formed with at least largely water-insoluble alcohols synthetic and / or natural origin with up to 14 carbon atoms, preferably with 4 to 8 carbon atoms and is carried out in particular with amyl alcohol and / or hexanol and that the alcohols are preferably partially separated from the surfactant mixture and are preferably reused.

7. The method according to claims 1 to 6, characterized gekennzeich¬ net that the extraction is carried out at temperatures in the range of about 50 to 100 C, preferably in the range of about 80 to 90 ° C as a one-step or multi-step process.

8. The method according to claims 1 to 7, characterized gekennzeich¬ net that alkyl-oligo-ethoxy and / or propoxy sulfates are used and converted to the surfactant mixture based on the alkyl ether sulfonates and alcohol-Oiigoalkoxylate.

9. The method according to claims 1 to 8, characterized gekennzeich¬ net that one works with alkyl ether sulfates based on coconut and / or palm kernel as a feed.

10. Use of the surfactant mixtures produced by the process of claims 1 to 9, in particular in a mixture with residual alcohol from the extraction stage for the tertiary petroleum production.

11. Embodiment according to claim 10, characterized gekennzeich¬ net that the surfactant mixtures according to the invention are used in admixture with other surfactants with a particularly strong hydrophobicity.