阅读说明：本技术 一种二氯丙醇盐酸共沸液的分离方法 (Method for separating dichloropropanol hydrochloric acid azeotropic liquid ) 是由 程终发 杨尚文 王宁宁 于 2020-12-10 设计创作，主要内容包括：本发明提供了一种二氯丙醇盐酸共沸液的分离方法,用饱和氯化钙盐析分离氯化氢,破坏三元体系,进一步分离出二氯丙醇。本发明使用无机盐盐析的方式分离二氯丙醇盐酸共沸液,避免了有机类带水剂的使用,与传统工业相比,更加安全环保。本发明在氮气保护下进行高温分离操作,有效避免产品在处理过程中的氧化,降低产品色度,提高品质。本发明有效分离二氯丙醇、氯化氢和氯化钙溶液：其中,二氯丙醇纯度＞99%,氯化氢经干燥后循环参与反应,氯化钙浓缩后循环使用,在生产高品质二氯丙醇的基础上,有效降低生产成本,且无三废产生,安全环保,利于工业化推广。(The invention provides a separation method of dichloropropanol hydrochloric acid azeotropic liquid, which is characterized in that saturated calcium chloride is used for salting out and separating hydrogen chloride, a ternary system is destroyed, and dichloropropanol is further separated. The invention uses the inorganic salt salting-out mode to separate the dichloropropanol hydrochloric acid azeotropic solution, avoids the use of organic water-carrying agents, and is safer and more environment-friendly compared with the traditional industry. The invention carries out high-temperature separation operation under the protection of nitrogen, effectively avoids the oxidation of the product in the treatment process, reduces the product chromaticity and improves the quality. The invention effectively separates dichloropropanol, hydrogen chloride and calcium chloride solution: wherein, the purity of the dichloropropanol is more than 99 percent, the hydrogen chloride circularly participates in the reaction after being dried, the calcium chloride is circularly used after being concentrated, the production cost is effectively reduced on the basis of producing the high-quality dichloropropanol, and the method has no three wastes, is safe and environment-friendly, and is beneficial to industrial popularization.)

1. A method for separating dichloropropanol hydrochloric acid azeotropic liquid is characterized by comprising the following steps:

1) mixing dichloropropanol hydrochloric acid azeotropic solution and calcium chloride solution to form a new azeotropic system and placing the new azeotropic system in an external steaming kettle;

2) heating to 100-120 ℃, making the outer vapor pass through a reflux device, wherein the gas is hydrogen chloride, and pumping the reflux liquid back to the outer steaming kettle;

3) and after externally steaming for 1-2 h, transferring the residual azeotropic liquid in the steaming kettle to a liquid separating device, standing for 4-6 h, separating a water phase from an organic phase, and drying the organic phase to obtain the dichloropropanol product.

2. The method according to claim 1, wherein the dichloropropanol hydrochloric acid azeotropic solution is generated in a process of preparing dichloropropanol from glycerol and hydrogen chloride, wherein the mass parts of the dichloropropanol, the hydrogen chloride and the water are 30-35: 15-25: 40 to 55.

3. The method according to claim 1, wherein the mass fraction of the calcium chloride solution is 40-60%; the mass ratio of the azeotrope to the calcium chloride solution is 1: 1.0 to 2.0.

4. The method as claimed in claim 1, wherein the aqueous phase in step 3) is concentrated under reduced pressure to obtain the target calcium chloride solution and concentrated water, the concentrated water is degraded and then stored in a reservoir for utilization, and the calcium chloride solution is recycled.

5. The method according to claim 4, wherein the concentration temperature is 80-100 ℃, the pressure is 0.05-0.07 MPa, and the degradation mode of the concentrated water is biodegradation or Fenton degradation.

6. The method of claim 1, wherein in step 2), before heating, nitrogen is used to replace the air in the system.

Technical Field

The invention relates to the technical field of fine chemicals, in particular to a method for separating dichloropropanol hydrochloric acid azeotrope.

Background

The prior production method of epoxy chloropropane mainly comprises 3 methods: propylene high-temperature chlorination process using propylene as a raw material, propylene acetate process, and glycerin chlorination process using glycerin as a raw material. The intermediates of all three processes form an azeotrope of dichloropropanol-water-hydrogen chloride. When the mixed aqueous solution of dichloropropanol and hydrogen chloride is used for saponification with calcium hydroxide and sodium hydroxide to prepare epoxy chloropropane, the hydrogen chloride in the azeotrope can be subjected to neutralization reaction with alkali liquor, so that the alkali consumption in the saponification process is high, a large amount of chloride is generated, and the sewage pollution is serious. The above problems are effectively solved if the dichloropropanol in the dichloropropanol-water-hydrogen chloride azeotrope can be separated.

The current method for separating the dichloropropanol-water-hydrogen chloride azeotrope mainly uses alkane organic solvent for extraction separation.

The patent CN200610161842.0 discloses a method for extracting and separating dichloropropanol from dichloropropanol hydrochloric acid solution, wherein the dichloropropanol is separated and purified by using halogenated hydrocarbon, aromatic ether and phosphate ester alkane organic solvent as an extracting agent.

Shanghai chlor-alkali chemical Co., Ltd discloses a method for preparing epoxy chloropropane from hydrochloric acid aqueous solution of dichloropropanol in patent CN200910046282.8, wherein the dichloropropanol is extracted and purified by adopting an alkane organic solvent such as alcohols, aromatic hydrocarbons or ethers.

The extraction and separation of the alkane organic solvent generally needs multi-stage extraction, multi-stage extraction equipment is added, the operation procedures are relatively complicated, the resource waste and the environmental pollution are caused, and the production cost is greatly increased.

The unit patents CN109134197A and CN109232183A disclose methods for separating dichloropropanol from dichloropropanol hydrochloric acid azeotropic liquid by using alkyl, ester and ether organic azeotropic agents respectively. The two methods have high separation efficiency and simple operation, and the entrainer can be recycled, but the entrainer is an organic matter, so that certain potential safety hazard and potential environmental pollution hazard exist.

Disclosure of Invention

The invention provides a separation method of dichloropropanol hydrochloric acid azeotropic liquid, which is characterized in that saturated calcium chloride is used for salting out and separating hydrogen chloride, a ternary azeotropic system is destroyed, and the dichloropropanol is further separated. The method mainly comprises the following steps:

(1) mixing dichloropropanol hydrochloric acid azeotropic solution and calcium chloride solution to form a new azeotropic system, and placing the new azeotropic system in an external steaming kettle, wherein the external steaming kettle is connected with a condensing device, an azeotropic solution recovery device and a liquid separating device;

(2) introducing nitrogen to replace air in the system, heating the temperature in the outer steaming kettle to 100-120 ℃, separating gaseous hydrogen chloride and condensate from the outer steam through a condensing device, pumping the condensate into other outer steaming kettles for circulating outer steaming, and drying and recycling the hydrogen chloride;

(3) after external steaming is carried out for 1-2 hours, transferring the residual azeotropic liquid in the steaming kettle to a liquid separating device, standing for 4-6 hours, separating a water phase and an organic phase, drying the organic phase to obtain a dichloropropanol product, and transferring the water phase to a concentrating device;

(4) and (3) carrying out reduced pressure concentration on the water phase to obtain a target calcium chloride solution and concentrated water, degrading the concentrated water and then utilizing the concentrated water in a reservoir, and recycling the calcium chloride solution.

Further, the dichloropropanol and hydrochloric acid azeotropic liquid in the step (1) is generated in the process of preparing dichloropropanol from glycerol and hydrogen chloride, wherein the mass parts of the dichloropropanol, the hydrogen chloride and the water are 30-35: 15-25: 40-55, wherein the preparation temperature of the calcium chloride solution is 60-100 ℃, the mass fraction of the calcium chloride solution is 40-60%, and the preferable mass fraction is 45-50%.

Further, the mass ratio of the azeotrope to the calcium chloride solution in the step (1) is 1: (1.0 to 2.0), preferably 1: (1.0-1.5).

Further, the drying mode in the steps (2) and (3) is drying by a drying agent.

Further, in the step (4), the concentration temperature is 80-100 ℃, the pressure range is 0.05-0.07 MPa, and the degradation mode of the concentrated water is biodegradation or Fenton degradation.

The invention reduces the solubility of hydrogen chloride gas and destroys the ternary negative azeotropic system of dichloropropanol-hydrogen chloride-water by the homoionic effect. At a lower temperature, the hydrogen chloride is distilled off.

In addition, the invention selects the strong electrolyte of calcium chloride which has high solubility, contains more chlorine in a single molecule and is slightly soluble in alkali corresponding to metal radical. Sodium chloride, potassium chloride and the like cannot reach high chlorine concentration due to low solubility, and have poor same-ion effect, while ferric chloride, copper chloride and the like are strong acid and weak base salts, and alkali corresponding to metal radicals of the ferric chloride and the copper chloride is insoluble alkali, and after the ferric chloride and the copper chloride are put in and steamed, the ferric chloride and the copper chloride are finally hydrolyzed to form weak acid buffer solution, so that hydrochloric acid residue is generated, and the subsequent purification is influenced.

The beneficial effects of the invention are as follows:

the invention uses the inorganic salt salting-out mode to separate the dichloropropanol hydrochloric acid azeotropic solution, avoids the use of organic water-carrying agents, and is safer and more environment-friendly compared with the traditional industry.

The invention carries out high-temperature separation operation under the protection of nitrogen, effectively avoids the oxidation of the product in the treatment process, reduces the product chromaticity and improves the quality.

The invention effectively separates dichloropropanol, hydrogen chloride and calcium chloride solution: wherein, the purity of the dichloropropanol is more than 99 percent, the hydrogen chloride circularly participates in the reaction after being dried, the calcium chloride is circularly used after being concentrated, the production cost is effectively reduced on the basis of producing the high-quality dichloropropanol, and the method has no three wastes, is safe and environment-friendly, and is beneficial to industrial popularization.

Detailed Description

The present invention is described in detail below by way of examples, which are intended to be illustrative only and not to be construed as limiting the scope of the invention, and one skilled in the art will be able to make variations within the scope of the invention based on the disclosure herein, in reagents, catalysts and reaction process conditions. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Part of the raw material specifications used in the examples:

the calcium chloride is industrial grade calcium chloride.

Example 1

Transferring 410.4kg of dichloropropanol hydrochloric acid azeotrope containing 25.7 percent of dichloropropanol into an external steaming kettle, adding 410kg of calcium chloride aqueous solution with the mass fraction of 45 percent, introducing nitrogen at the flow rate of 100L/min to replace air in the system, starting a stirring and condensing device, and heating the internal temperature of the external steaming kettle to 105 +/-5 ℃ for external steaming. And (3) separating gaseous hydrogen chloride and condensate from the external vapor through a condensing device, steaming for 2 hours, pumping 123.5kg of the obtained condensate into other external steaming kettles for circulating external steaming, and drying the hydrogen chloride to obtain 91.1kg of hydrogen chloride for recycling.

Transferring 604.3kg of the residual azeotropic solution in the external steaming kettle into a liquid separating device, standing for 4-6 h, separating to obtain 518.0kg of a water phase and 86.3kg of an organic phase, drying the organic phase to obtain 82.9kg of dichloropropanol, transferring the water phase into a concentration kettle, concentrating and externally steaming under the pressure of 0.05MPa to obtain 409.9kg of calcium chloride aqueous solution with the mass fraction of 45%, 108.1kg of concentrated water, recycling the calcium chloride aqueous solution, and introducing the concentrated water into a reservoir after Fenton degradation.

The dichloropropanol obtained is detected to be yellowish transparent liquid, the purity of the dichloropropanol is 99.5%, the primary recovery rate is 78.6%, and the chroma (Hazen) is 17.

Example 2

428.1kg of dichloropropanol hydrochloric acid azeotrope containing 20.5 percent of dichloropropanol is transferred into an external steaming kettle, 640kg of calcium chloride aqueous solution with the mass fraction of 50 percent is added, nitrogen is introduced according to the flow rate of 100L/min to replace air in the system, a stirring and condensing device is started, and the temperature in the external steaming kettle is heated to 115 +/-5 ℃ for external steaming. And (3) separating gaseous hydrogen chloride and condensate from the external vapor through a condensing device, steaming for 2 hours, pumping 148.7kg of the obtained condensate into other external steaming kettles for circulating external steaming, and drying the hydrogen chloride to obtain 124.5kg of hydrogen chloride for recycling.

Transferring 793.6kg of residual azeotropic liquid in the external steaming kettle into a liquid separating device, standing for 4-6 h, separating to obtain 721.1kg of water phase and 72.5g of organic phase, drying the organic phase to obtain 69.6kg of dichloropropanol, transferring the water phase into a concentration kettle, concentrating and externally steaming under the pressure of 0.07MPa to obtain 639.8kg of calcium chloride aqueous solution with the mass fraction of 50%, 81.3kg of concentrated water, recycling the calcium chloride aqueous solution, and performing fenton degradation on the concentrated water and then putting the concentrated water into a reservoir.

The dichloropropanol obtained is detected to be yellowish transparent liquid, the purity of the dichloropropanol is 99.6 percent, the primary recovery rate is 79.4 percent, and the chroma (Hazen) is 16.