阅读说明：本技术 一种含氟化氢和氯化氢的混合气体的综合利用方法 (Comprehensive utilization method of mixed gas containing hydrogen fluoride and hydrogen chloride ) 是由 李云峰 薛旭金 韩建军 耿梦湍 李凌云 段宾 李喜 叶家铭 张亚辉 于 2020-07-17 设计创作，主要内容包括：本发明属于氟化工技术领域,具体涉及一种含氟化氢和氯化氢的混合气体的综合利用方法。本发明利用三乙胺对含氟化氢和氯化氢的混合气体进行多级吸收,生成的三乙胺盐酸盐为沉淀物,三乙胺三氢氟酸为溶液,因此经简单固液分离即可实现上述产品分离开,再经过后续精制过程,完成低价值氟化氢和氯化氢向高价值三乙胺三氢氟酸和三乙胺盐酸盐产品的转化。本发明所述方法具有工艺简单,操作性强,产品附加值高,满足有机氟行业需求,工艺闭路循环,不产生二次污染等优点。(The invention belongs to the technical field of fluorine chemical industry, and particularly relates to a comprehensive utilization method of a mixed gas containing hydrogen fluoride and hydrogen chloride. According to the invention, triethylamine is utilized to carry out multistage absorption on the mixed gas containing hydrogen fluoride and hydrogen chloride, the generated triethylamine hydrochloride is a precipitate, triethylamine trihydrofluoride is a solution, and therefore, the products can be separated through simple solid-liquid separation, and the conversion of low-value hydrogen fluoride and hydrogen chloride into high-value triethylamine trihydrofluoride and triethylamine hydrochloride products is completed through a subsequent refining process. The method has the advantages of simple process, strong operability, high product added value, capability of meeting the requirements of the organic fluorine industry, closed cycle of the process, no secondary pollution and the like.)

1. A method for comprehensively utilizing a mixed gas containing hydrogen fluoride and hydrogen chloride is characterized by comprising the following steps: the method comprises the following steps:

1) multi-stage absorption: introducing mixed gas containing hydrogen fluoride and hydrogen chloride into a multistage absorption reactor for reaction, wherein the multistage absorption reactor is connected in series, and 50-75% by volume of triethylamine is filled in each stage of reactor; the reaction temperature is 10-40 ℃, and the pressure is-1 to-5 KPa; discharging mixed material liquid in the first-stage reactor when the solid-liquid ratio of the material liquid in the first-stage reactor at the initial end reaches 10-50%, then sequentially transferring next-stage material liquid to the first-stage reactor, and continuing to react;

2) filtering and separating: carrying out solid-liquid separation on the mixed feed liquid in the first-stage reactor obtained in the step 1), and measuring the concentration of fluorine ions in the filtrate; if the concentration of the fluorine ions in the obtained filtrate is less than 350g/L, conveying the filtrate to the last stage reactor, and simultaneously supplementing triethylamine until 50-75% of the volume of the last stage reactor continues to perform absorption reaction;

3) and (3) refining a product: solid obtained by solid-liquid separation in the step 2) is a triethylamine hydrochloride crude product, and filtrate with the fluorine ion concentration not less than 350g/L is a triethylamine trihydrofluoric acid crude product; dissolving the triethylamine hydrochloride crude product by using an organic solvent, and carrying out reduced pressure distillation to obtain a triethylamine hydrochloride product; and (3) rectifying the triethylamine trihydrofluoric acid crude product to obtain a triethylamine trihydrofluoric acid product.

2. The method for comprehensive utilization of a mixed gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 1, wherein: and (3) introducing inert gas into the multistage reactor for replacement before use, wherein the treatment time is 10-30 min.

3. The method for comprehensively utilizing a mixed gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 1, wherein: the multistage reactor in the step 1) is formed by connecting 2-4 stages of reactors in series.

4. The method for comprehensively utilizing a mixed gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 1, wherein the purification process of the crude triethylamine hydrochloride in the step 3) comprises:

dissolving a triethylamine hydrochloride crude product into an organic solvent, wherein the volume of the organic solvent is 2-4 times of the mass of the triethylamine hydrochloride crude product; filtering to remove impurities, distilling the filtrate under reduced pressure, concentrating to 50-75% of the original volume, and stopping distillation; filtering the concentrated slurry, drying the obtained solid to obtain a triethylamine hydrochloride product, and returning the obtained filtrate which is mother liquor containing triethylamine hydrochloride to a reduced pressure distillation system; wherein the organic solvent is polar protic solvent.

5. The method of comprehensively utilizing a mixed gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 4, wherein: the temperature of the reduced pressure distillation is 20-60 ℃, and the pressure is-0.09 to-0.1 MPa; the recovered liquid obtained by vacuum distillation can be reused as an organic solvent.

6. The method of comprehensively utilizing a mixed gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 4, wherein: and filtering the concentrated slurry, and drying the obtained solid for 0.5-2 hours at the temperature of 80-120 ℃ under the protection of nitrogen to obtain the triethylamine hydrochloride product.

7. The method for comprehensively utilizing the mixed gas containing hydrogen fluoride and hydrogen chloride as claimed in claim 1, wherein the rectification temperature of the triethylamine trihydrofluoric acid crude product in the step 3) is 70-85 ℃, and the reflux ratio is 0.5-2.5; triethylamine separated in the rectification process is recycled as absorption liquid in the multistage absorption process.

Technical Field

The invention belongs to the technical field of fluorine chemical industry, and particularly relates to a comprehensive utilization method of a mixed gas containing hydrogen fluoride and hydrogen chloride.

Background

A great amount of mixed tail gas containing hydrogen fluoride and hydrogen chloride is generated in the production process of the fluorine chemical industry, and the currently adopted treatment method is to obtain fluorine-containing hydrochloric acid by water absorption and then separate the fluorine by precipitation. However, the fluorine and chlorine are active in chemical property, so that the treatment difficulty is high, and a large amount of acid wastewater containing fluorine and chlorine is generated in the treatment process, so that secondary pollution to the environment is caused. Therefore, the search for more effective treatment method of mixed tail gas containing hydrogen fluoride and hydrogen chloride is an important prerequisite for clean production of fluorine chemical industry.

At present, the treatment method of fluorine-containing hydrochloric acid as a byproduct of the fluorine chemical industry comprises the following steps: precipitation and adsorption. CN201611033201.7 discloses a method for treating fluorine-containing waste hydrochloric acid, which comprises the steps of firstly adding high-alumina fly ash into the fluorine-containing waste hydrochloric acid to leach out total chloride ions of the high-alumina fly ash to prepare an aluminum-rich fluorine-containing waste hydrochloric acid solution, then adding calcium chlorate into the aluminum-rich fluorine-containing waste hydrochloric acid, and performing dissolution, polymerization and liquid-solid separation to obtain a liquid which is a polyaluminium chloride product, wherein fluorine impurity ions in the waste hydrochloric acid are left in a solid phase in the form of calcium fluoride. The method has the following defects: firstly, AlF is generated in the leaching process₃The precipitation causes F, Al resource waste, and the synthesized calcium fluoride particles are extremely fine in the fluorine precipitation process and difficult to separate from the polyaluminium chloride, so that the purity and the performance of the product are reduced. CN201711042879.6 discloses a fluorine-containing hydrochloric acid defluorination method, which comprises the following steps: 1) firstly, weighing fluorine-containing hydrochloric acid, putting the fluorine-containing hydrochloric acid into a reaction device, then adding silica gel into the reaction device, enabling the silica gel to be fully contacted with the fluorine-containing hydrochloric acid, and carrying out adsorption reaction on hydrogen fluoride in hydrochloric acid and the silica gel to remove fluorine ions;2) and oscillating the silica gel after adsorbing fluorine in a constant-temperature oscillator in a water bath for 1-2 h at the water bath temperature of 20-30 ℃, washing with a regenerant until the silica gel is neutral, draining the silica gel with filter paper, putting the silica gel into a reaction device, separating fluorine from the silica gel to regenerate the silica gel, and using the regenerated silica gel for removing fluorine with hydrochloric acid in the next cycle. The method has complex flow, and a large amount of fluorine-containing acidic wastewater is generated in the regeneration process of the silica gel, so that the treatment is difficult; meanwhile, the method is suitable for treating hydrochloric acid with low fluorine-containing impurities, and if the fluorine content is too high, side reactions can be generated to influence the adsorption and regeneration of the silica gel.

Therefore, a method for rapidly, efficiently and environmentally comprehensively utilizing mixed tail gas containing hydrogen fluoride and hydrogen chloride is urgently needed to be developed, so that the high-efficiency and high-value utilization of resources and the clean production of fluorine chemical industry are realized.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a comprehensive utilization method of a mixed gas containing hydrogen fluoride and hydrogen chloride, which directly treats the mixed gas containing hydrogen fluoride and hydrogen chloride in a fluorine chemical by a simple absorption separation method, realizes high-efficiency and high-quality utilization of low-grade fluorine and chlorine resources, and solves the problems of difficult treatment of fluorine-containing hydrochloric acid, large discharge amount of acid wastewater, low resource utilization rate and the like in the traditional process.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

a comprehensive utilization method of mixed gas containing hydrogen fluoride and hydrogen chloride comprises the following steps:

1) multi-stage absorption: introducing mixed gas containing hydrogen fluoride and hydrogen chloride into a multistage absorption reactor for reaction, wherein the multistage absorption reactor is connected in series, and 50-75% by volume of triethylamine is filled in each stage of reactor; the reaction temperature is 10-40 ℃, and the pressure is-1 to-5 KPa; discharging mixed material liquid in the first-stage reactor when the solid-liquid ratio of the material liquid in the first-stage reactor at the initial end reaches 10-50%, then sequentially transferring next-stage material liquid to the first-stage reactor, and continuing to react;

2) filtering and separating: carrying out solid-liquid separation on the mixed feed liquid in the first-stage reactor obtained in the step 1), and measuring the concentration of fluorine ions in the filtrate; if the concentration of the fluorine ions in the obtained filtrate is less than 350g/L, conveying the filtrate to the last stage reactor, and simultaneously supplementing triethylamine until 50-75% of the volume of the last stage reactor continues to perform absorption reaction;

3) and (3) refining a product: solid obtained by solid-liquid separation in the step 2) is a triethylamine hydrochloride crude product, and filtrate with the fluorine ion concentration not less than 350g/L is a triethylamine trihydrofluoric acid crude product; dissolving the triethylamine hydrochloride crude product by using an organic solvent, and carrying out reduced pressure distillation to obtain a triethylamine hydrochloride product; and (3) rectifying the triethylamine trihydrofluoric acid crude product to obtain a triethylamine trihydrofluoric acid product.

Preferably, before the multistage reactor is used, inert gas is introduced in advance to perform system replacement on a reaction system, and the treatment time is 10-30 min.

Preferably, the multistage reactor in the step 1) is formed by connecting 2-4 stages of reactors in series.

Preferably, the refining process of the crude triethylamine hydrochloride in the step 3) is as follows:

dissolving a triethylamine hydrochloride crude product into an organic solvent, wherein the volume of the organic solvent is 2-4 times of the mass of the triethylamine hydrochloride crude product; filtering to remove impurities, distilling the filtrate under reduced pressure, concentrating to 50-75% of the original volume, and stopping distillation; filtering the concentrated slurry, and drying the obtained solid to obtain a triethylamine hydrochloride product; the obtained filtrate is mother liquor containing triethylamine hydrochloride and returns to a reduced pressure distillation system; wherein the organic solvent is polar protic solvent.

Preferably, the temperature of the reduced pressure distillation is 20-60 ℃, and the pressure is-0.09 to-0.1 MPa; the recovered liquid obtained by reduced pressure distillation can be reused as an organic solvent.

Preferably, after the concentrated slurry is filtered, drying the obtained solid for 0.5-2 hours at the temperature of 80-120 ℃ under the protection of nitrogen to obtain the triethylamine hydrochloride product.

Preferably, the rectification temperature of the triethylamine trihydrofluoric acid crude product in the step 3) is 70-85 ℃, and the reflux ratio is 0.5-2.5; triethylamine separated in the rectification process can be used as absorption liquid in the multistage absorption process for recycling.

The chemical equation for the reaction of hydrogen fluoride and hydrogen chloride with triethylamine in the present invention is as follows:

(CH₃CH₂)₃N + HCl → (CH₃CH₂)₃NHCl↓

(CH₃CH₂)₃N + 3HF → (CH₃CH₂)₃N（HF）₃

the triethylamine hydrochloride is a precipitate, and the triethylamine trihydrofluoric acid is a solution, so the products can be separated by simple solid-liquid separation, and the conversion of low-value hydrogen fluoride and hydrogen chloride into high-value triethylamine trihydrofluoric acid and triethylamine hydrochloride products is completed through a subsequent refining process.

The invention adopts an absorption separation method to directly treat the tail gas containing the hydrogen fluoride and the hydrogen chloride, and the removal rate of the hydrogen fluoride and the hydrogen chloride in the mixed tail gas can reach more than 98.5 percent after the multi-stage absorption treatment. Compared with the prior art, the method has the advantages that,

the invention realizes the conversion of low-added-value hydrogen fluoride and hydrogen chloride to high-added-value triethylamine trihydrofluoric acid and triethylamine hydrochloride products, realizes the high-efficiency and high-quality utilization of low-grade fluorine and chlorine resources, and solves the problems of difficult treatment of fluorine-containing hydrochloric acid, large discharge amount of acid wastewater, low resource utilization rate and the like in the traditional process. The method has the advantages of simple process steps, strong operability and high treatment efficiency, meets the requirements of the organic fluorine industry, can realize closed cycle of the whole process, does not cause secondary pollutants, and lays a foundation for promoting energy conservation, emission reduction and clean production of the fluorine chemical industry.

Drawings

FIG. 1 is a process flow diagram of the method for the integrated utilization of a gas mixture containing hydrogen fluoride and hydrogen chloride according to the invention.

Detailed Description

The present application is described in further detail below with reference to specific examples.