DD240009A1 - PROCESS FOR CLEANING AN ALKANSULFONATE SOLUTION - Google Patents

Abstract

The invention relates to the use in the production of alkanesulfonates via the sulfochlorination of paraffins and the subsequent saponification of the alkanesulfonyl chlorides with dilute sodium hydroxide solution, resulting in unsaponifiable portions of sodium alkanesulfonate and common salt. After separation of the unsaponifiable material, the saline-containing sulfonate solution is cooled and gravity separates the high-boiling sub-layer and the sulfonate-rich upper layer. The separators can contain internals to keep the separation times short and to ensure the quality of the separation products even with increased overall throughput. An improved separation result is achieved in that the majority of upper layer in a first Trenngefäî preferably with Platteneinbauten at temperatures below 20 degrees C and the sulfonatarme, saline rich sub-layer after cooling to 0 to 10 degrees C of further sulfonate-rich shares in a 2nd Trenngefäî after Passing a coalescer be separated.

Description

Field of application of the invention

The invention relates to a process for purifying alkanesulfonate solutions which are formed in the saponification of alkanesulfonyl chlorides with dilute sodium hydroxide solution and therefore contain sodium chloride as by-product.

Characteristic of the known technical solutions After saponification of alkanesulfonyl chlorides with dilute sodium hydroxide solution and the separation of the undissolved

unsaponifiable components of the saline-containing sulfonate solution, the sulfonate solution to temperatures below 20 ⁰ Cabgekühlt, wherein an emulsion is formed which is generally rectangular in a round or Horizontalstromabscheider

Cross-section is separated. Low-salt sulfonates according to the method described in F. Asinger "Chemistry and Technology of Paraffinic Hydrocarbons" To prepare the process, the saline sulfonate solution after the separation of the unsaponifiable fractions after DD-PS 4 610 are cooled to temperatures below 25 ⁰ C. According to DD-PS 118 082, the deposition of saline solutions of saline sulfonate solutions can be more effective in two Carrying out stages, first cooling the alkanesulfonate solution preferably to 10 to 15 ⁰ C, the separating,

more or less alkansulfonathaltige, saline underlayer of the alkansulfonatreichen topsheet is worked up in a known manner, is separated and this lower layer after mixing with about ^{_1/10 of} top layer in a second cooling step to 0 to 10 ° C, preferably 4 to 6 ° C, cooled and the now sulfonatarme, saline rich layer of the

separates sulfonate-rich layer. ^v ""

It is also known that the purification of the alkanesulfonate two-stage at temperatures of about 10 ⁰ C and 5 ° C, respectively

can be performed, but why a considerable expenditure of cooling energy is required.

The known technical solutions accomplish this separation of both layers exclusively using the Gravity, which at the given, relatively low separation speeds to large dimensions of the separation apparatus

leads. In the case of the usually continuously operated separating vessels, it is necessary to optimize between still acceptable expenditure on equipment and free space as well as the maximum permissible sulphonate content of the underlayer, which as a rule is supplied to the sewage network. You will very quickly reach the limits if you want to increase your system capacity.

Object of the invention

The aim of the invention is to increase the effect of the phase separation in order to make the process for alkanesulfonate production more economical and environmentally friendly.

Explanation of the essence of the invention

The invention has for its object to change both the separation conditions and the dispersity of the emulsion to be separated so that at a given separation speed of the liquid-liquid system, the separation shortened or at constant main equipment dimensions, the separation rate is increased to an improved separation result to reach. This object is achieved by a process for purifying an alkanesulfonate solution which is formed in the saponification of alkanesulfonyl chlorides with dilute sodium hydroxide solution as a low-sodium, alkanesulfonate-rich, lighter phase in admixture with a sodium chloride-rich, alkanesulfonate heavy phase, the mixture being separated in one or more stages to separate the heavier phase is cooled to temperatures below 20 ⁰ C in order to achieve the fullest possible phase separation in a short time by the present invention, the mixture is introduced in the first stage at temperatures above 10 ⁰ C in a separator, i ι the Platteneinbauten at a distance of 0.1 to 0.5 times Trennapparatinnendurchmessers, preferably 0.2 times, can be arranged away from the inlet of the sodium alkanesulfonate solution to be separated, which have a length of 0.3 to 0.8 times the separation distance, preferably 0.6 to 0.7 times, wherein the Plates an angle from 5 to 20 , Preferably 10 °, form the flow horizontal, that the alkansulfonatreiche upper layer was separated in a known manner and further processed and the sodium chloride-rich lower phase after cooling to below 10 ° C and a face velocity of 3 x 10 ~ ⁴ to 1.5 TO ^"2 m ~ see ^"1, preferably 4.5 x 10 ~ ^4-3 - 10 ~ ³ m see" ¹ .einem Koaleszerzugeführt is composed of a layer with irregular, breitverteiltem pore spectrum and then again separated into two layers, the upper phase united with the upper phase of the first stage.

Surprisingly, it has been found that coalescers can be used to solve the problem, although it is generally known that surfactants counteract the coalescence and low temperatures and low interfacial tensions, as in the present case, do not promote the Koaleszenzneigung.

By installing inclined plates, between which the product flows along, the separation path of the disperse droplets is shortened substantially compared to the empty tube, resulting in a shortening of the separation time at a given separation speed.

In addition, there are opportunities for coalescence during the outflow of separated droplets from the oblique plate, which additionally accelerates the separation process. It makes sense to use the internals only if the viscosity of the top layer still allows a flow of the drops, usually at temperatures of 10-15 ° C.

The obtained at the end of the first separator sulfonate-rich, cooking salt poorer upper layer is further processed in a known manner, while the high-boiling, somewhat sulfonate-containing lower layer is again cooled to temperatures of 0-10 ⁰ C, which in turn forms an emulsion.

This dispersion of very small droplets is transferred by means of a coalescer into a second separator in a well separable dispersion with increased separation rate and then separated. The result is another top layer that contains recyclable sulfonate and a process wastewater that, due to its low sulfonate content, is less polluting to the environment than before.

The second cooling of the sulfonate-rich sublayer and the separation of the resulting emulsion by means of coalescer and gravitational separation apparatus can take place and also in two stages.

Embodiment ·

The implementation of the method according to the invention can be seen from the following examples.

Example 1:

1 I · h ^"1 a saline containing Sulfonatlösungmit 27,50 wt .-% residue and 4.48 wt .-% saline was continuously separated in a separation tube of 85 mm diameter and 850 mm length after cooling to 15 ° C.

The top layer drawn off at the end of the separation vessel contained 36.15% by weight of monosulfonate and 1.85% by weight of sodium chloride, and the bottom layer had a content of 2.25% by weight of monosulfonate and 7.05% by mass of common salt.

When using a plate pack, consisting of two parts, each with ten plates at a distance of 5 mm, which was arranged at a distance of 0.2 times Trennapparatinnendurchmessers from the inlet, had a length of 0.67 times the separation distance and their plates at an angle of 10 ° to the flow horizontal, the contents changed as follows:

Upper layer lower layer

37.00% by weight of monosulfonate 1.85% by weight of monosulfonate

1.75 mass% of common salt "7.45 mass% of common salt.

With four times the throughput of the Monosulfonatgehalt the withdrawn from the conduit underclass increased by about 1O ⁰ C, while the lower layer of the plate baffles was even sulfonatärmer than 1 lh ^-1.

Example 2:

30 "I · h ¹ a saline underlayer from a first separation stage with 0.38 wt .-% monosulfonate and 7.64 wt .-% of sodium chloride were cooled down to 4.5 ° C continuously in a separation tube of 150 mm diameter and The deposited top layer contained 1.87% by weight of monosulfonate and 7.47% by weight of sodium chloride, the bottom layer had a content of 0.35% by weight of monosulfonate and 7.75% by mass of common salt By using a coalescer with a layer thickness of 25 mm, which consisted of 45 layers of glass fiber fleece with fiber diameters of 10.15 and 25 μπη, the monosulfonate content of the underlayer was lowered to 0.15 mass%, the flow velocity being 5 × 10 ~ ⁴ m · s ~ ¹ .

Claims (1)

-1 - Z4U uua Invention claim: A process for purifying an alkanesulfonate solution which is formed in the saponification of alkanesulfonyl chlorides with dilute sodium hydroxide solution as low-sodium, alkansulfonatreiche lighter phase mixed with a sodium chloride-rich, alkansulfonatarmen heavier phase, wherein the separation of the heavier phase, the mixture one or more stages to temperatures below 20 ⁰ C. is cooled in order to achieve the fullest possible phase separation in a short time, characterized in that the mixture is introduced in the first stage at temperatures above 1O ⁰ C in a separator in which Platteneinbauten at a distance of 0.1 to 0.5fachen Separator inner diameter, preferably of 0.2 times, can be arranged away from the inlet of the sodium alkanesulfonate solution to be separated, which have a length of 0.3 to 0.8 times the separation distance, preferably 0.6 to 0.7 times, wherein the plates at an angle of 5 to 20 °, preferably 10 °, to the flow gshorizontalen that the alkanesulfonate-rich upper phase is separated and processed in a known manner and the sodium chloride-rich lower phase after cooling to below 10 ⁰ C with a flow rate of 3 10 " ⁴ to 1.5 10 ~ ² m · see" ¹ , preferably 4, 5 10 ~ ^{4 to} 3 · 10 ~ ³ m · see " ^{1 is} fed to a coalescer, which consists of a layer of irregular, widely distributed pore spectrum, and then in turn separated into two layers, the upper phase with the upper phase of the first stage is united.