RU2277082C1 - Method of the vacuum rectification of ethylene chlorohydrin - Google Patents

Abstract

FIELD: petrochemical industry; methods of production of ethylene chlorohydrin.

SUBSTANCE: the invention is pertaining to the field of petrochemical industry, in particular, to the method of the vacuum rectifying separation of ethylene chlorohydrin (EChH) both from the mixtures with the high-boiling hydrins and at the regeneration of EChH in the process of the synthesis of the different compounds on its base. The method provides for the vacuum rectification of EChH with the continuous feeding of ethylene oxide into the distillation residue section of the column of separation up to its content in the distillation residue liquid within the interval of 0.01-0.15 mass % at the temperatures exceeding 90°C. As a rule the ethylene oxide is introduced in the form of the solution in the material flow of the phase of the rectification. The method ensures reduction of the corrosion activity of the medium, the increased reliability and the service life of the equipment, stabilization of the commercial EChH quality and the raised efficiency.

EFFECT: the invention ensures reduction of the corrosion activity of the medium, the increased reliability and the service life of the equipment, stabilization of the commercial EChH quality and the raised efficiency.

2 cl, 1 tbl, 9 ex

Description

The invention relates to the field of chemistry of organic compounds, and in particular to a method for the distillation separation of ethylene chlorohydrin (ECG) both from mixtures with high boiling hydrines and during the regeneration of ECG during the synthesis of various compounds based on it.

ECG is widely used in industry as a solvent for fats, oils, resins, in the synthesis of plasticizers, special types of synthetic rubber, choline chloride, etc.

The product has high demands on purity, color and metal content. According to the requirements of TU No. 6-01-05757587-58-94, the content of the main substance should be at least 99.6% (premium), 99.2% (first grade), the iron content should not exceed 0.005%, the content of hydrogen chloride - not more than 0.015%, density -1,200-1,205 g / cm ³ , appearance - a clear, colorless or light yellow liquid.

In the industrial production of ECG by the method of liquid-phase hydrochlorination of ethylene oxide, simultaneously with the target, up to 93 wt.%, By-products are obtained - high-boiling esters of ECG (2-chloroethyl ether of ethylene glycol HGDEG, 2-chloroethyl ether of diethylene glycol HGTEG, etc.), from the mixture with which ECG is isolated by vacuum distillation.

ECG and high boiling hydrins are thermolabile substances. In the process of distillation separation of ECG already at a temperature of 100-110 ° C, thermal decomposition reactions begin to occur (Zilberman IE Investigation of the thermal transformations of ethylene chlorohydrin. ZhPKh, 1985, No. 11, p.2529). Thermal degradation products worsen the quality of commercial ECG and lead to its increased corrosion activity. Therefore, the hardware design of the method of vacuum distillation of ECG is difficult in a corrosion respect.

Similar difficulties are encountered in the production of complex organic compounds based on ECG, for example, in the production of choline chloride, formals, etc.

A known method of distillation separation of ECG with a concentration of 98-99 wt.% (DE 19648887, class C 07 With 3 1/36, date prior. 26.11.96). According to this method, the separation of ECG from the reaction mixture containing high-boiling hydrins is carried out in vacuum on a packed or other distillation column. Cold ECG - raw served on the top plate or above the nozzle. High purity ECG is taken from the top of the column. High-boiling components in the reverse flow go into the cube of the column, the temperature of the cube is maintained below 110 ° C. Moreover, the equipment used for this method is made of glass, polytetrafluoroethylene and polyolefins. The disadvantages of this method are the need to use non-metallic structural materials, which is quite difficult, expensive and requires increased costs during operation, low purity of commodity ECG, which is only 98-99%.

Closest to the proposed method is the vacuum distillation specified in the article "The use of titanium in the process of obtaining choline chloride" by A.A. Pozdeeva, E.I. Antonovskaya and others from the collection "Titanium for the national economy". M .: Nauka, 1976, p. 218-222. The target ECG by this method is distilled off on a distillation column operating at a cube temperature of 70-80 ° C and a residual pressure of 10 mm RT. Art. The resulting ECG should contain at least 98% of the main product, organic impurities not more than 0.4%, water in the range up to 1.6%, hydrogen chloride not more than 0.005% and be colorless. The use of titanium equipment for implementing this method is limited by the following conditions: temperature not higher than 90 ° C, water content not less than 0.3-0.5%, acidity in terms of hydrogen chloride not more than 0.15%, contact time with the apparatus at 90 ° C no more than 50 hours

The authors of the article believe that the presence of water as an oxygen supplier, providing the creation of a passivating film on titanium, is necessary to ensure the corrosion resistance of titanium.

This method has the following disadvantages: rectification at temperatures not exceeding 90 ° C, severely limits the performance of the process, because the capacity of the distillation column decreases due to the large volume of vapor with increasing vacuum in the system, the presence of water in the distilled medium leads to a violation of the quality of commercial ECG, because water is taken together with the distillate.

An object of the present invention is to reduce the corrosiveness of the medium and thereby increase the reliability and durability of the equipment, stabilize the quality of commercial ECG and increase the productivity of the method.

According to the proposed method, vacuum distillation of the ECG is carried out in the presence of ethylene oxide while continuously supplying it to the bottom of the separation column. The supply of ethylene oxide is carried out in such a way that its concentration in the bottom part is 0.01-0.15 wt.%.

Dosing of ethylene oxide is carried out in any way: ethylene oxide in a gaseous or liquid state or in the form of a solution of ethylene oxide in the material stream (distillate, initial mixture) of the rectification stage.

The presence of ethylene oxide in the cubic part of the distillation column allows the use of metallic structural materials for processing the process, allows to stabilize the high quality of the obtained ECG, increase the temperature in the cubic part, and therefore, carry out the process at a higher residual pressure and thereby increase the productivity of the method.

The invention is illustrated by the following examples.

Example 1 (comparative).

A mixture of ECG with high boiling hydrins (2-chloroethyl ether of ethylene glycol HGDEG, 2-chloroethyl ether of diethylene glycol HGTEG, etc.) of the following composition in wt.%: Water is fed to a distillation unit with an efficiency of two theoretical plates in the exhaustive part and two theoretical plates in the strengthening part. - 0.5; hydrogen chloride - 0.06; dioxane 0.02; ECG - 31.92, high-boiling hydrins - 67.5. At a cube temperature of 90 ° C, ECG is taken from the top of the unit in the form of a distillate, maintaining the reflux ratio equal to 0.5, and the residual pressure in the system is 10 mm Hg. Metal samples — steel — 3 or titanium VT 1-0 — are placed in the still bottom. The analysis of the distillate is carried out according to TU No. 6-01-05757587-58-94. The obtained distillate contains in wt.%: ECG - 97.301, water -1.597, hydrogen chloride - 0.193, dioxane - 0.499, unidentified light impurities - 0.196, HGDEG and HGTEG - 0.214, has a density of 1.192 g / cm ³ . Thus, the quality of the allocated ECG does not meet the requirements of TU.

The distillation distillation unit capacity was taken as 1.

Example 2 (comparative).

The experiment is carried out analogously to example 1.

As food for distillation separation serves a mixture with a content, wt.%: ECG - 90.1; water - 0.3; dioxane - 0.124; hydrogen chloride - 0.006; HGDEG and HGTEG - 9.47. At a cube temperature of 80 ° C, a reflux ratio of 0.5, a residual pressure of 10 mm Hg the distillate of the following composition is taken from the top of the unit: water - 0.35; hydrogen chloride - 0.012; dioxane 0.62; unidentifiable light components - 0.475; ECG - 98.27, HGDEG and HGTEG - 0.273. The density of 1.2017 g / cm ³ . The corrosion rate in the test medium was 1-0 8.5 mm / year for VT titanium and 3 14.4 mm / year for steel. The test duration was 720 hours. Comparative productivity 1.

Examples 3 to 9

The experiments are carried out analogously to examples 1 and 2, while in examples 3-6, ethylene oxide is supplied to the bottom part in gaseous or liquid form, maintaining a given concentration of ethylene oxide. Examples 7, 8 are made with feeding ethylene oxide into the bottom part in the form of a solution in the initial mixture of 1.459 and 9.189 wt.%, Respectively. Example 9 is made with the feed into the cubic part of a solution of ethylene oxide in the distillate concentration of 5.0 wt.%.

The results obtained during the experiments are presented in the table.

An analysis of the results shows that the introduction of ethylene oxide (OE) into the bottoms of the distillation unit at temperatures exceeding 90 ° C allows us to stabilize the quality of the released ECG, the distillate obtained does not contain excessive concentrations of hydrogen chloride, water and other decomposition products. In addition, this allows the process to be carried out using metallic materials, as corrosion rates are reduced by more than 100 times.

The capacity of the distillation unit increased by more than 3.7 times.

An increase in the content of ethylene oxide in bottoms liquid over 0.15 wt.% Leads to a decrease in the content of the basic substance and an overspending of ethylene oxide.

Table
The test results of the proposed method of vacuum distillation of ethylene chlorohydrin No. p / p The name of indicators Experience Number one 2 3 four 5 6 7 8 9 one The residual pressure in the system, mm Hg 10 10 one hundred 200 fifty 200 200 one hundred 200 2 The composition of the initial mixture, wt.% Water 0,500 0,300 0,020 0,030 0.010 0,030 0,030 0,020 0,025 Hydrogen chloride 0,060 0.006 0,070 0,110 0.008 0,090 0,120 0,080 0,083 Dioxane 0,020 0.124 0,020 0.124 0,093 0,089 0.118 0.015 0.051 ECG 31,920 90,100 32,000 87,000 90,500 86,500 87,000 30,000 88,150 Σ HGDEG and HGTEG 67,500 9,470 67,890 12,736 9,389 13,291 12,732 69,885 11,691 3 The temperature of the bottom liquid, ° C 90 80 130 130 90 130 130 130 130 four The concentration of OE in bottoms, wt.% Ots. Ots. 0.10 0.10 0.01 0.15 0.05 0.10 0.13 5 The composition of the distillate (commercial product) Water 1,597 0.35 0,060 0,040 0,020 0,034 0,040 0,060 0,027 OE Ots. Ots. 0.008 0.003 Ots. 0.159 Ots. 0.006 0,082 Hydrogen chloride 0.193 0.012 0.002 0.006 0.003 Ots. 0.006 0.002 Ots. Dioxane 0.499 0.620 0,069 0.147 0.105 0.105 0.155 0.056 0.056 Light impurities 0.196 0.475 0,052 0,043 0.003 0,084 0,050 0,063 0.019 ECG 97,301 98,270 99,670 99.64 99.71 99.26 99.62 99.65 99,600 Σ HGDEG and HGTEG 0.214 0.273 0.139 0.121 0.159 0.322 0.129 0.163 0.217 6 Density, g / cm ³ 1,192 1,2017 1,2021 1,2020 1,2023 1,2000 1,2023 1,2021 1,2020 7 Test duration, hour 522 720 638 582 720 535 615 560 597 8 Comparative performance one one 3,1 3,7 1.7 3,7 3,7 3,1 3,7 9 Corrosion rate, mm / year Titanium VT 1-0 12.5 8.5 0.02 0.01 0.01 0.009 0.01 0.02 0.009 Steel 3 35.10 14.40 0.33 0.31 0.30 0.27 0.31 0.29 0.28

The corrosion rate determined according to GOST 9.905-82, GOST 9.907-83, GOST 9.908-85 in the conditions of the experiment was: for titanium VT 1-0 12.5 mm / year, steel 3 - 35.1 mm / year. The duration of the test was 522 hours

Claims (2)

1. The method of vacuum distillation of ethylene chlorohydrin, characterized in that the process is carried out with a continuous supply of ethylene oxide in the bottom part of the separation column until it is contained in the bottom liquid in the range of 0.01-0.15 wt.% At temperatures exceeding 90 ° C. 2. The method according to claim 1, characterized in that the ethylene oxide is introduced in the form of a solution in the material stream of the rectification stage.