阅读说明：本技术 一种保险粉生产废液制备2-巯基乙醇的方法 (Method for preparing 2-mercaptoethanol from sodium hydrosulfite production waste liquid ) 是由 王国清 于 2020-04-28 设计创作，主要内容包括：本发明公开了一种保险粉生产废液制备2-巯基乙醇的方法,包括如下步骤：1)将保险粉生产废液置入搅拌釜中,升温至50-55℃后开始搅拌成稳定的液体；2)升压至0.15-0.25MPa,保持搅拌下缓慢加入氢氧化钠溶液,控制反应液pH在8.5-10.0之间,反应90min后,停止搅拌保温30min；3)将反应液在-30至-50KPa真空度的精馏塔中进行精馏,控制塔釜温度157-159℃,塔顶温度70-75℃,将塔顶出气经循环水冷却后,再经-10℃到-15℃的盐水冷凝器冷凝,冷凝液即为2-巯基乙醇。本发明的有益效果是：本发明利用保险粉生产过程中产生废液生产2-巯基乙醇,能够使保险粉生产过程中产生的废液达到无害化分类处理,生产出纯度在98％以上的2-巯基乙醇产品,并副产硫酸钠产品。(The invention discloses a method for preparing 2-mercaptoethanol from sodium hydrosulfite production waste liquid, which comprises the following steps: 1) putting the sodium hydrosulfite production waste liquid into a stirring kettle, heating to 50-55 ℃, and then starting stirring to form stable liquid; 2) increasing pressure to 0.15-0.25MPa, slowly adding sodium hydroxide solution while keeping stirring, controlling pH of the reaction solution to 8.5-10.0, reacting for 90min, stopping stirring, and keeping the temperature for 30 min; 3) rectifying the reaction liquid in a rectifying tower with vacuum degree of-30 to-50 KPa, controlling the temperature of the tower bottom at 157 and 159 ℃ and the temperature of the tower top at 70 to 75 ℃, cooling the discharged gas at the tower top by circulating water, and condensing the cooled gas by a brine condenser at the temperature of-10 ℃ to-15 ℃, wherein the condensate is the 2-mercaptoethanol. The invention has the beneficial effects that: the method utilizes the waste liquid generated in the production process of the sodium hydrosulfite to produce the 2-mercaptoethanol, can carry out harmless classification treatment on the waste liquid generated in the production process of the sodium hydrosulfite, produces the 2-mercaptoethanol product with the purity of more than 98 percent, and produces a sodium sulfate product as a byproduct.)

1. A method for preparing 2-mercaptoethanol from sodium hydrosulfite production waste liquid is characterized by comprising the following steps:

1) putting the sodium hydrosulfite production waste liquid into a stirring kettle, heating to 50-55 ℃, and then starting stirring to form stable liquid;

2) increasing pressure to 0.15-0.25MPa, slowly adding sodium hydroxide solution while keeping stirring, controlling pH of the reaction solution to 8.5-10.0, reacting for 90min, stopping stirring, and keeping the temperature for 30 min;

3) rectifying the reaction liquid in a rectifying tower with a vacuum degree of-30 to-50 KPa, controlling the temperature of a tower kettle at 157 and 159 ℃ and the temperature of a tower top at 70 to 75 ℃, cooling the discharged gas at the tower top by circulating water, condensing the gas by a brine condenser with the temperature of-10 to-15 ℃, wherein the condensate is 2-mercaptoethanol, evaporating and concentrating the residual liquid at the tower bottom, washing the crystallized liquid by methanol, and drying the crystallized liquid to obtain the sodium sulfate.

2. The method for preparing 2-mercaptoethanol from sodium hydrosulfite production waste liquid according to claim 1, wherein the concentration of the sodium hydroxide solution is 20-40 wt%.

Technical Field

The invention relates to the field of waste recovery, and in particular relates to a method for preparing 2-mercaptoethanol from sodium hydrosulfite production waste liquid.

Background

2-hydroxyethanol, also known as β -mercaptoethanol, 2-hydroxyethylthiol, β -mercaptoethanol) is an important organic compound, having the chemical formula C₂H₆OS, molecular weight 78.14, CAS number 60-24-2. 2-mercaptoethanol is a colorless transparent liquid with little thiol odor, flash point: 73 ℃, melting point: boiling at-100 deg.CPoint: 157-: 1.1143, relative vapor density (air ═ 1): 2.69, is easily soluble in organic solvents such as water, ethanol, ether and the like, and can be mixed and dissolved with benzene in any proportion. The 2-mercaptoethanol can be used as an organic synthesis intermediate for the production of pesticides, medicines, dyes and photographic chemicals. It can also be used as adjuvant in rubber, textile, plastic and paint industries. The polymer grade high-purity mercaptoethanol can be used as a blending agent of vinyl chloride and the like, a polymerization catalyst, a polymer cross-linking agent and a curing agent. The 2-mercaptoethanol is approved by the United states food and drug administration, and can be used as an additive for blow molding containers for food packaging made of styrene and methyl methacrylate ternary resin.

At present, domestic sodium hydrosulfite production enterprises all adopt a sodium formate method to produce sodium hydrosulfite. In order to inhibit side reactions in the production process of sodium hydrosulfite, namely to eliminate a byproduct sodium thiosulfate in the synthesis process of the sodium hydrosulfite so as to ensure the main content of the sodium hydrosulfite, ethylene oxide (C) is added in the synthesis process of the sodium hydrosulfite by each production enterprise₂H₄O) to mask the side reactions to sodium thiosulfate. Because the ethylene oxide is added in the production process of the sodium hydrosulfite, the ethylene oxide reacts with the sodium thiosulfate to generate NaS₂O₃-CH₂CH₂OH (Bunte salt) and NaOH, the reaction equation is: c₂H₄O+Na₂S₂O₃+H₂O＝NaS₂O₃-CH₂CH₂OH + NaOH. The waste liquid generated by the side reaction belongs to dangerous waste, and the main component is NaS₂O₃-CH₂CH₂OH (Bunte salt) with the content of more than 90 percent, and the balance of a small amount of water, inorganic salt and the like.

Patent ZL03112293.0 a method for utilizing crude methanol rectification raffinate in the sodium hydrosulfite production process to produce sodium formate, disclose recovering sodium formate from it, use for the sodium hydrosulfite production adjuvants. However, in the production practice, it is found that the specific technical scheme in the patent publication not only has low purity of the recovered sodium formate, but also does not reprocess the waste organic matter generated in the process of producing sodium formate from the crude methanol rectification residual liquid in the sodium hydrosulfite production process to produce products with higher added value, but also generates organic waste as dangerous waste after pre-concentration, vacuum concentration and crystallization extraction, and delivers the dangerous waste to qualified units for centralized incineration treatment. The treatment difficulty of the crude methanol rectification residual liquid in the production process of sodium hydrosulfite is high, the treatment cost is high, the amount of the generated dangerous waste is large, the waste organic matters are not recycled to produce products with higher added values, and a lot of valuable organic matters are greatly wasted.

Patent ZL201410548871.7 a method for producing ethanethiol by utilizing crude methanol rectification residual liquid in the production process of sodium hydrosulfite discloses that crude methanol rectification residual liquid is produced in the production process of sodium hydrosulfite, and ethanethiol is produced from the crude methanol rectification residual liquid. However, in production practice it was found that: the specific technical scheme in the patent not only has low purity and low yield in the production of the ethanethiol, but also has high energy consumption in the rectification process, and the rectification residues are used as hazardous wastes and are handed to qualified units for centralized incineration treatment, so that the cost for treating the crude methanol rectification residual liquid and producing the ethanethiol in the production process of the sodium hydrosulfite is high, and the amount of the generated hazardous wastes is hardly reduced.

Disclosure of Invention

The invention provides a method for preparing 2-mercaptoethanol from sodium hydrosulfite production waste liquid, aiming at the problem of incomplete classification and recovery of the waste liquid generated by sodium formate method for preparing sodium hydrosulfite.

The technical scheme for solving the technical problems is as follows: a method for preparing 2-mercaptoethanol from sodium hydrosulfite production waste liquid comprises the following steps:

1) putting the sodium hydrosulfite production waste liquid into a stirring kettle, heating to 50-55 ℃, and then starting stirring to form stable liquid;

2) increasing the pressure to 0.15-0.25MPa, slowly adding a sodium hydroxide solution while keeping stirring, controlling the pH of the reaction solution to be 8.5-10.0, reacting for 90min, stopping stirring and preserving the temperature for 30min, wherein the reaction formula is as follows:

NaS₂O₃-CH₂CH₂OH+NaOH＝HSCH₂CH₂OH+Na₂SO₄；

3) rectifying the reaction liquid in a rectifying tower with a vacuum degree of-30 to-50 KPa, controlling the temperature of a tower kettle at 157 and 159 ℃ and the temperature of a tower top at 70 to 75 ℃, cooling the discharged gas at the tower top by circulating water, condensing the gas by a brine condenser with the temperature of-10 to-15 ℃, wherein the condensate is 2-mercaptoethanol, evaporating and concentrating the residual liquid at the tower bottom, washing the crystallized liquid by methanol, and drying the crystallized liquid to obtain the sodium sulfate.

Wherein the concentration of the sodium hydroxide solution used in the step 2) is 20-40 wt%.

The invention has the beneficial effects that: the invention utilizes the waste organic substance Bunte salt generated in the production process of the sodium hydrosulfite to produce the 2-mercaptoethanol, can enable the waste organic substance generated in the production process of the sodium hydrosulfite to achieve harmless classification treatment, produces the 2-mercaptoethanol product with the purity of more than 98 percent, and produces the sodium sulfate product as a byproduct.

Detailed Description

The present invention is described below with reference to examples, which are provided for illustration only and are not intended to limit the scope of the present invention.