SK41995A3 - Process for the production of unhydrous ethylen chlorhydrin with high purity - Google Patents

Abstract

To the reactor of the first stage (R01) with ethylenechlorohydrine is through the mixer (Z01) under continuous circulation of the reactive shaft added dry salt acid, later through the mixer (Z02) ethylene oxide. The reactive heat is removed by the heat exchanger (E01). Concurrently with the salt acid saturation washing the gases begins in the absorber over (R01) by undercooled raw ethylenechlorohydrine from the reactor of the second stage (R02) and to the (R02) is added ethylene oxide through the mixer (Z03). Degas from (R02) is conducted to the bottom part of the second absorber, countercurrently is sprinkled by the raw ethylenechlorohydrine, saturated salt acid, outgoing overflow from (R01). The raw ethylenechlorohydrine is continuously conducted to the reservoir (H01), from which it is lead to rectification. The pure water-free product, ethylenechlorohydrine is removed as a distillate from the head of rectifying column (C01).

Description

The present invention relates to a process for the production of anhydrous ethylene chlorohydrin (ECH) of high purity by reacting ethylene oxide (EO) with hydrogen chloride (HCl) in a two-stage reactor.

The prior art

ECH was first obtained by reacting ethylene glycol with hydrogen chloride in 1859 and later by reacting ethylene glycol with Blnny chloride. The reaction of ethylene b with hypochlorous acid - chlorohydrination was the most important, but in this case a dilute aqueous solution of ECH was obtained. There are still several procedures for preparing ECH, but they have no practical application. Anhydrous ECH is more easily obtained by reacting EO with HCl. The reaction is carried out with a 10% molar excess of HCl in vertical ceramic or glass packed columns. The reaction gases are passed to the top, the resulting ECH condenses and flows to the reservoir. Such a method can be used in both laboratory and operational scale (reference # 2). The by-product of this synthesis is 2, (2 chloroethoxy) ethanol, which is formed by the reaction of ECH with EO. Synthesis conditions are: temperature 30 ° C, molar ratio EO: HCl = 1: 1, reactant feed rate 650-750 g / h (reference # 1).

The industrial scale used a wet process for the production of ECH utilizing the reaction of ethylene with chlorine in an aqueous medium, producing both 1.1 dichloroethane and ECH. Obtaining anhydrous ECH is uneconomical and a 5 to 6% aqueous solution of ECH was subjected to dehydrochlorination and production of EO (reference # 1).

The most preferred method for obtaining anhydrous ECH is the synthesis of HCl and EO. The reaction is strongly exothermic, the reaction heat is 150.72 KJ / mol ECH. The Czechoslovak patent 100737 (Literature 3) solves a process for continuous production of anhydrous ECH from EO and HCl in liquid phase. that Ba EO and HCl are fed through perforated tubes, disks or ceramic frits to a cylindrical reactor filled with a liquid that can be mixed with ECH and dissolves EO and HCl but does not react chemically with either of these in an amount of 100-1000 1 per hour of reactor volume, preferably at a reaction temperature of up to 70 ° C, whereby the heat-heated mixture rises to the thermosiphon, where it is cooled and returned to the reactor, whereby circulation of the reaction mixture occurs due to different specific weights. The apparatus for producing anhydrous ECH according to the method comprises a cylindrical tower reactor of corrosion resistant material, preferably of iron, pooled inside, provided at the bottom with perforated pipes for EO and HCl inlet, the reactor being connected to a thermosiphon via water and drain lines. cooler and in the upper part of the reactor there is an overflow to the liquid product and a connection to the degassing and entrained liquid separator.

British Patent 660835 (4) describes a process for producing ethylene glycol and ECH by introducing EO vapors into aqueous HCl. In this process, ECH is formed as an azeotrope with water and such a product is only suitable for the production of EO by classical alkaline dehydrochlorination.

BSD patent 968902 (5) is based on EO or alkylene oxide-containing gases which are introduced into anhydrous alkylene hydrine saturated with HCl. The production method is mainly used for the production of ethylene and propylene chlorohydrin and has the advantage over (4) that no side reactions run, operating at normal temperatures and pressures. Suitable off-gases containing alkylene oxide are obtained e.g. in distillation of EO, in degassing of EO containers or in the production of EO by direct oxidation. It has the advantage, compared to the processes known at the time, that from the alkylene oxide-containing off-gases in one process a high-percentage, anhydrous alkylene-chlorohydrin is obtained, which is easily purified to a suitable purity for synthesis by simple distillation. The disadvantage of this procedure is the difficulty of regulating the synthesis in one

stage, unsuitability of the apparatus for the processing of concentrated alkylene oxide.

USSR 130502 (6) describes a process for obtaining anhydrous ECH by hydrochlorination of EO in an ECH environment in the presence of a phosphate, which increases product yield and reduces apparatus corrosion. The molar ratio of continuously dosed dry HCl and EO reactants was 1.3 to 1.5. Temperature 50 ^and C. The reactor dimensions and reagent dosing rate are adjusted so that the residence time of the product in the reaction zone is about 10h. The use of phosphate makes it possible to use ordinary steel as the construction material of the apparatus.

The disadvantage of this process is the contamination of the product with ferric chloride. phosphate and a lower selectivity of the reaction due to the molar excess of EO and the risk of purification of the product due to the excess of EO.

Disadvantages of the mentioned processes such as low reactor load due to poor heat dissipation, low selectivity of the reaction and formation of 2 (2 chloroethoxy) ethanol due to insufficient mixing of the reactants and low excess of HCl up to 10 mol%. respectively. molar excess EO. contamination of the product with metals or admixtures of diluted EO. insufficient disposal of residual reactants; and poor process control and process safety. are removed by the production method of the present invention.

SUMMARY OF THE INVENTION

The advantage of the process for producing ECH according to the invention is that. that a high molar excess of HCl in liquid ECH in the range of 10 to 40 mol% in the first stage of the reactor makes it possible to achieve high selectivity by increasing the likelihood of reactants meeting. which at the same time suppresses the formation of 2. (2 chloroethoxy) ethanol, which results from the subsequent reaction of ECH with EO. The product addition flows continuously through the absorber to the second stage of the reactor, where the molar excess of HCl in ECH is neutralized by EO to the desired value.

Perfect homogenization of gaseous reactants in ECH in special mixers. placed outside the reactor, utilizing the very good solubility of both reactants in ECH. increases the likelihood of encountering reactants, thereby helping to increase selectivity.

The excess of HCl in ECH in both reactor stages is controlled by the functional dependence of the conductivity of the reaction medium at a given temperature from the HCl concentration. allowing immediate intervention in the process.

Due to the toxicity of the off-gases and their aggressiveness, the process is conducted in this way. that the off-gas from the first stage of the reactor is fed to the bottom of the abeorber located above the first stage of the reactor and is countercurrently scrubbed with neutralized ECH from the second stage of the reactor, cooled to 10 to -20 ° C. The exhaust from the second stage of the reactor is passed to the bottom of the second absorber, where it is countercurrently scrubbed with raw ECH, saturated with HCl, leaving the overflow from the first stage of the reactor. Such an arrangement makes it possible to achieve excellent results also in terms of environmental protection.

The distillation of crude ECH Ba is carried out under vacuum on a packed or other rectification column with a minimum of 4 theoretical plates. The cold crude ECH is injected onto the upper tray, or over the packed bed. The high-boiling ¹ ECH i higher fractions are removed from the top of the column as reflux and passed to the column reboiler, with decomposition of 2 (2 chloroethoxy) ethanol to 1,4-dioxane preventing the temperature in the reboiler below 110 ° C.

Industrial usability

The process uses glass, teilone and polyolefin as the construction materials of the apparatus, which allows to achieve high product purity almost without the presence of metals for the use of the product mainly in the pharmaceutical industry.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

The reactor (ROD according to the diagram in the accompanying drawing is dosed with 2750? ECH and the reactor (R02) 1500? ECH. Both reactors and the whole plant according to the diagram in drawing Ba are inerted with nitrogen. • with continuous circulation of the reaction batch, dry * HCl is added until the desired molar excess is quantified by measuring the conductivity of the mixture.Then, EO is added via the mixer (Z02), and the resulting heat of reaction is discharged through the exchanger (E01). The flow of EO and HCl into the mixers is gradually adjusted to provide the desired molar excess of HCl.Along with the saturation of HCl, the scrubbing of the offsets in the absorber above (ROD subcooled neutralized ECH from the reactor (R02) begins). (R02) to increase the conductivity of the mixture and thus the HCl concentration, the EO is dosed via the mixer (Z03) so that the The temperature of the mixture in the reactor (R02) must not exceed 30 ° C. The raw neutralized ECH is continuously discharged into a storage tank (HOD from which it is led for rectification).

Technological conditions according to example 1:

(ROD HCI flow: EO flow Excess HCl: temperature 8.89 mol / h 7.06 mol / h 33.3 mol. 31.4 »C (R02) EO flow temperature Selectivity: EO Conversion: 1.82 mol / h 20 'C 95.1 « 99.2 * Example 2 Preparation procedure as in Technological conditions: Example 1. (ROD HCI flow : 19.61 mol / h

EO flow rate: 17.18 mol / h

Excess HCl: 28.2 mol%.

Temperature: 39 ° C (R02) EO flow rate: 2.40 mol / h Temperature: 30 · C

EO conversion: 98.72 * Selectivity: 89.85 *

Example 3

Preparation procedure as in Example 1. Technological conditions:

(R01) HCl flow : 25.90 mol / h EO flow : 23.53 mol / h Excess HCl : 21 * mol. temperature : 50 ° C (R02) EO flow : 2.19 mol / h temperature : 25C EO conversion : 98.9 * selectivity : 91 *

PATENT CLAIMS

Claims (7)

PATENT CLAIMS A process for preparing anhydrous ethylene chlorohydrin by reaction with hydrogen chloride in a two-stage reactor, characterized in that: The reaction is carried out in an environment of liquid ethylene chlorohydrin with an excess of hydrogen chloride of 10 to 40% in the first stage and neutralization of the excess hydrogen chloride with ethylene oxide in the second stage of the reactor. 2. The excess of hydrogen chloride in ethylene chlorohydrin in both reactor stages is controlled by the functional dependence of the conductivity of the reaction medium on the hydrogen chloride concentration at a given temperature. 3. Homogenization of the reactants in the mixers achieves selectivity up to 96% and conversion of ethylene oxide 98 to 99 *. 4. The reaction in the first step is conducted at temperatures of preferably from 20 to 60 ° C, the excess of hydrogen chloride allowing a selectivity of from 90 to 100 ° C to be achieved, in the second step the reaction is conducted at a temperature of preferably 10 to 30 ° C. 5. The waste from the first stage of the reactor is fed to the bottom of the absorber located above the first stage of the reactor and is countercurrently scrubbed with raw neutralized ethylene chlorohydrin from the second stage of the reactor, cooled to 10 to -20 ° C. of the second absorber and countercurrently is sprinkled with crude ethylene chlorohydric saturated hydrogen chloride leaving the overflow from the first stage of the reactor. 6. Pure 98-99% ethylene chlorohydrin is withdrawn as distillate from the top of the rectification column, into the upper part of which ethylene chlorohydrin is injected, at a boiling temperature of preferably up to 110 ° C. 7. Glass, teflon, polyolefins are used for apparatus construction.