CN102923662A

CN102923662A - Method for separating hydrogen fluoride and hydrogen chloride in chloropyridine derivative fluorination process

Info

Publication number: CN102923662A
Application number: CN2012105020337A
Authority: CN
Inventors: 姜友法; 贺书泽; 丁泽升; 丁剑剑; 谢邦伟; 卜标; 陈康
Original assignee: Jiangsu Yangnong Chemical Co Ltd
Current assignee: Jiangsu Youjia Chemistry Co., Ltd.; Jiangsu Yangnong Chemical Co Ltd
Priority date: 2012-11-30
Filing date: 2012-11-30
Publication date: 2013-02-13
Anticipated expiration: 2032-11-30
Also published as: CN102923662B

Abstract

The invention provides a separation technology of the mixed tail gas of hydrogen fluoride and hydrogen chloride in the chloropyridine derivative fluorination process. The tail gas after fluorination contains the mixture of hydrogen chloride and hydrogen fluoride; the molar ratio of the hydrogen chloride to hydrogen fluoride is (98:2)-(60:40); and the reparation method comprises the following steps: performing pressure cooling of the mixed gas so as to change the hydrogen fluoride into liquid and realize separation, and performing one-level or multi-level water absorption and recovery of the gas hydrogen chloride and trace hydrogen fluoride to obtain a qualified technical hydrochloric acid product. The separation method provided by the invention can recover raw materials, reduce the consumption of the raw materials and realize recovery of the byproduct.

Description

The method of separating fluorine hydride and hydrogenchloride in the chloro-pyridine derivative fluorination process

Technical field

The present invention relates to the separating technology of hydrogen fluoride and hydrogenchloride in the chloro-pyridine derivative fluorination process.

Background technology

In the synthetic operation of fluoridizing of DTMP, requirement hydrogen fluoride is excessive, and generate hydrogen chloride gas in the reaction process, what reaction system ejected like this is hydrogenchloride and hydrofluoric mixed gas, if this mixed gas is without separation, be to recycle, thereby cause the increase of raw material consumption and the increase of three wastes discharge amount.

And traditional separation method has three kinds of chemical precipitation, flocculation sediment, absorption etc., and chemical precipitation method generally adopts calcium salt precipitation method, i.e. feeding lime in the waste water makes fluorion and calcium ion generate the CaF2 precipitation and removes.This technique have method simple, process the advantages such as convenient, that expense is low, but exist process after water outlet be difficult to up to standard, body refuse sedimentation slowly and the shortcoming such as dehydration difficulty; The flocculation agent that flocculent precipitation is commonly used is aluminium salt.Aluminium salt utilizes Al after being added in the water ³⁺With F ^-Complexing and aluminium salt hydrolysis intermediate product and the last Al (OH) that generates ₃(am) alumen ustum is swept ligand exchange, physical adsorption, the volume of fluorion and is acted on the fluorion of removing in the water.Compare with calcium salt precipitation method, aluminium salt flocculent precipitation has advantages of that added amount of chemical is few, treatment capacity is large, can reach discharging standards after the primary treatment, aluminium salt flocculent precipitation also exists obvious shortcoming, namely use scope little, if fluorine content is large, the coagulating agent usage quantity is many, and processing costs is larger, produces sludge quantity many; The fluoride ion removing effect is subjected to SO in the operation factors such as agitation condition, settling time and the water ₄ ^2-, Cl ^-Impact Deng negatively charged ion is larger, and effluent quality is stable not; The sorbent material commonly used that suction type is used for defluorination mainly contains activated alumina, clinoptilolite, activated magnesia, the higher hydroxyapatite of adsorption capacity of fluoride ion, zirconium white etc. have also been reported in recent years, absorption method is effective for the fluoride ion removing of trace, but exist the problems such as the processing water yield is little, loading capacity is low to be not suitable for scale operation, present invention focuses on the difference according to hydrogenchloride and hydrogen fluoride boiling point difference and solubleness, and then by device reinforcement differences such as the many suctions of pressurization absorptions, reach both and separate.

Summary of the invention

The object of the invention provides hydrogen fluoride in a kind of chloro-pyridine derivative fluorination process and the separating technology of hydrogenchloride, to reclaim raw material, reduces raw material consumption, and the recovery that realizes by product.

The present invention is achieved by the following technical solutions:

The separating technology of hydrogen fluoride and hydrogenchloride mixed tail gas in the one class chloro-pyridine derivative fluorination process is provided, the tail gas that obtains behind described the fluoridizing contains hydrogenchloride and hydrofluoric mixture, wherein hydrogenchloride and hydrofluoric molar ratio are 98/2 ~ 60/40, it is characterized in that: mixed gas is first by the pressurization cooling, make hydrogen fluoride become liquid, realize to separate, still obtain qualified technical hydrochloric acid goods for the hydrogenchloride of gas and micro-hydrogen fluoride absorb recovery through one or more levels water again.

The preferred 2-chloro-5-trichloromethylpyridine of described chloro-pyridine derivative or 2,3-, two chloro-5-trichloromethylpyridines (DTMP).

Described pressurization cooling, pressure is preferably in the 0.1-5Mpa scope.

Described pressurization cooling can be finished through one or more levels pressurization refrigerating unit.

When described hydrogenchloride and micro-hydrogen fluoride absorb recovery through one-level water, preferably control the F ionic concn and pump dilute hydrochloric acid less than under the 100PPM.

When described hydrogenchloride and micro-hydrogen fluoride absorb recovery through multistage water, can process according to following dual mode:

One-level absorbs control F ionic concn less than 100PPM, and the F ionic concns of different concns that obtain at different levels are less than the hydrochloric acid goods of 100PPM thereafter;

Perhaps

One-level absorbs HCl to saturated, and subsequently adjustings at different levels obtain the F ionic concn of different concns less than the hydrochloric acid goods of 100PPM; And the mother liquor reuse that the F ionic concn reduces after one-level is accumulated HF concentration greater than 5% aftertreatment one-level absorption liquid, processed is to system.Processing mode is processed routinely, for example works as HF concentration and reaches 20%, adds calcium chloride under the room temperature, and reaction generates precipitation Calcium Fluoride (Fluorspan), filters out Calcium Fluoride (Fluorspan), and at this moment hydrogen fluoride concentration drops to about 3% in the mother liquor, continues retrieval system with this mother liquor again and applies mechanically.

Compared with prior art, the separation method of invention can reclaim raw material, reduces raw material consumption, and the recovery that realizes by product.

Description of drawings

Fig. 1 is the schematic flow sheet of separating technology of the present invention.

Embodiment:

Below among each embodiment, the pressurization heat-eliminating medium is-20 ℃ water, it is the recirculated water of ambient temperature that water absorbs the falling-film tower heat-eliminating medium.

Embodiment 1

System pressure 3.5MPa-4.0MPa adopts one-level pressurization cooling, and three grades of water absorb, and institute goes out hydrochloric acid one-level content 32%, hydrofluoric acid 80ppm, and hydrochloric acid secondary content 31.5%, hydrofluoric acid 30ppm, three grades of content 31.5% hydrofluoric acid of hydrochloric acid are 2ppm.

Embodiment 2

System pressure 3.5MPa-4.0MPa adopts the two-stage pressurizing cooling, and three grades of water absorb, and institute goes out hydrochloric acid one-level content 32.6%, hydrofluoric acid 10ppm, and hydrochloric acid secondary content 31.5%, hydrofluoric acid 5ppm, three grades of content 31.1% hydrofluoric acid of hydrochloric acid are 2ppm.

Embodiment 3

System pressure 3.5MPa-4.0MPa adopts three grades of pressurization coolings, and three grades of water absorb, and institute goes out hydrochloric acid one-level content 33.6%, and hydrofluoric acid 5ppm, hydrochloric acid secondary content 31.5%, hydrofluoric acid 2ppm, three grades of content 31.1% of hydrochloric acid, hydrofluoric acid are zero 2ppm.

Embodiment 4

System pressure 3.5MPa-4.0MPa adopts the two-stage pressurizing cooling, and secondary water absorbs, and institute goes out hydrochloric acid one-level content 33.6%, hydrofluoric acid 5ppm, hydrochloric acid secondary content 31.5%, hydrofluoric acid 2ppm.

Claims

1. the separating technology of hydrogen fluoride and hydrogenchloride mixed tail gas in the chloro-pyridine derivative fluorination process, the tail gas that obtains behind described the fluoridizing contains hydrogenchloride and hydrofluoric mixture, wherein hydrogenchloride and hydrofluoric molar ratio are 98/2 ~ 60/40, it is characterized in that: mixed gas is cooled off by pressurization first, make hydrogen fluoride become liquid, realize to separate, still obtain qualified technical hydrochloric acid goods for the hydrogenchloride of gas and micro-hydrogen fluoride absorb recovery through one or more levels water again.

2. separating technology claimed in claim 1, it is characterized in that: described chloro-pyridine derivative is 2-chloro-5-trichloromethylpyridine or 2,3-, two chloro-5-trichloromethylpyridines.

3. separating technology claimed in claim 1 is characterized in that: described pressurization cooling, pressure is in the 0.1-5Mpa scope.

4. separating technology claimed in claim 1 is characterized in that: described pressurization cooling is finished through one or more levels pressurization refrigerating unit.

5. separating technology claimed in claim 1 is characterized in that: described hydrogenchloride and micro-hydrogen fluoride absorb through one-level water and reclaim, and control F ionic concn pumps dilute hydrochloric acid less than under the 100PPM.

6. separating technology claimed in claim 1, it is characterized in that: described hydrogenchloride and micro-hydrogen fluoride absorb through multistage water and reclaim, wherein, one-level absorbs control F ionic concn less than 100PPM, and the F ionic concns of different concns that obtain at different levels are less than the hydrochloric acid goods of 100PPM thereafter.

7. separating technology claimed in claim 1 is characterized in that: described hydrogenchloride and micro-hydrogen fluoride absorb through multistage water and reclaim, and wherein, one-level absorbs HCl to saturated, and subsequently adjustings at different levels obtain the F ionic concn of different concns less than the hydrochloric acid goods of 100PPM; And the mother liquor reuse that the F ionic concn reduces after one-level is accumulated HF concentration greater than 5% aftertreatment one-level absorption liquid, processed is to system.