CN100999439B

CN100999439B - Preparation method of pentafluoroethane

Info

Publication number: CN100999439B
Application number: CN2007100000054A
Authority: CN
Inventors: 吕剑; 张伟; 寇联岗; 石磊; 王博; 庞国川; 何飞; 崔文华
Original assignee: Xian Modern Chemistry Research Institute
Current assignee: Xian Modern Chemistry Research Institute
Priority date: 2007-01-04
Filing date: 2007-01-04
Publication date: 2010-10-06
Anticipated expiration: 2027-01-04
Also published as: CN100999439A

Abstract

This invention relates to a preparation method of pentafluoroethane (HFC-125). It takes hydrogen fluoride (HF) and tetrachloroethene (PCE) as raw material, used two reaction vessel through two-step gaseous phase fluoridation to prepare HFC-125. The first reactor mainly fluorate PCE to synthesize 2,2 - dichloro-1 ,1,1 - halothane (HCFC-123) and 2-chloro-1 ,1,1,2 - tetrafluoroethane (HCFC-124); the second reaction mainly fluorate at least one of HCFC-123, HCFC-124 to synthesize HFC-125. Using distillation column to take PCE from the products of first reactor, and then circulate to first reactor. Take phase separator to separate HF, HCFC-123 and HCFC-124 from products of first and second reactor, HF can circulate to first and second reactor for continues reaction, HCFC-123 and HCFC-124 can be recycled to the second reactor continued reaction, but also can through distillation and separation to obtain HCFC-123 and HCFC-124 products. The invention mainly for prepare pentafluoroethane.

Description

The preparation method of pentafluoride ethane

Technical field

The present invention relates to a kind of preparation method of pentafluoride ethane, relate in particular to and a kind ofly prepare HCFC-123 and HCFC-124, the method that makes the further catalytic fluorination of HCFC-123 and HCFC-124 produce pentafluoride ethane then by zellon and hydrogen fluoride gas phase catalytic reaction.This method is mainly used in the preparation of pentafluoride ethane and the preparation of HCFC-123 and HCFC-124.

Background technology

Pentafluoride ethane (abbreviating HFC-125 as) is a kind of fluorinated hydrocarbons compound to atmospheric ozone layer safety, mainly be used as 1-chloro-1 at present, the substitute of 1-methylene fluoride (HCFC-22) refrigeration agent in addition, also is widely used as whipping agent, solvent, propellant, fire-fighting medium and dry etching agent.

The method of known industrial synthetic HFC-125 has three kinds.A kind of method is to fluoridize suitable precursor with HF in the presence of fluorination catalyst.U.S. Pat 3755477, US6417413B1 and CN1057516C disclose and have comprised that fluoridizing precursor is zellon (hereinafter referred PCE) or 2,2-two chloro-1,1, the method of 1-Halothane (hereinafter referred HCFC-123), U.S. Pat 6503865 and Chinese patent CN1157352C comprise that openly fluoridizing precursor is HCFC-123 or 2-chloro-1,1,1, the method of 2-Tetrafluoroethane (hereinafter referred HCFC-124), Chinese patent CN1793094A and CN1286786C openly fluoridize the method that precursor is a tetrafluoroethylene.Second method is the synthetic HFC-125 of HCFC-124 disproportionation under the effect of catalyzer, as the CN1232487C disclosed method.The third method is to be raw material with the trieline, under the effect of catalyzer, through fluoridizing, chlorination, fluoridizing synthetic HFC-125 of three steps, as Chinese patent CN1840506A and CN1660728A disclosed method.

The raw material HCFC-124 of second method needs at first to fluoridize PCE by first method or HCFC-123 obtains.The third method steps is more, and each step reaction type difference, and required catalyzer is also different, technology and actually operating relative complex.Compare with back two kinds of methods, first method has advantages such as reaction type is single, step is less, technology is simple, raw material is easy to get, and is the most widely used method of industrial synthetic HFC-125.

In the method for first kind of synthetic HFC-125, when being precursor with the tetrafluoroethylene, the fluoridation heat release is violent, and the polyreaction of tetrafluoroethylene easily takes place, and has the danger of blast.And when being raw material with HFC-123, HFC-124, need at first to obtain by fluoridizing PCE.Therefore, adopt in the presence of fluorination catalyst with HF and fluoridize suitable precursor when preparing HFC-125, preferably the PCE that can obtain from the market with industrial acceptable price is as raw material.

Aforesaid method is except productive target product HFC-125, also obtain many intermediates and by product simultaneously, as one or more isomer and unreacted hydrogen fluoride, PCE and the byproduct hydrogen chloride of HCFC-123, HCFC-124, HCFC-133a, HFC-134a and CFC-115.Intermediate product, as HCFC-123 and HCFC-124, and unreacted hydrogen fluoride usually it can be crossed distillation and separates from product stream, and be recycled in the fluorination reactor further fluoridation.

All adopt single fluorination reactor in the above-mentioned patent, owing to the difference that has boiling point and phase between the intermediate product HCFC-123, the HCFC-124 that are circulated to fluorination reactor and unreacted PCE and the HF, and all there are azeotropism in HCFC-123, HCFC-124 with HF, cause entering the material proportion instability of fluorination reactor easily, cause the fluoridation instability, be difficult to operation; Even cause the reactive system material not have the phenomenon of HF, and can cause the quick coking and deactivation of catalyzer, have a strong impact on life of catalyst.Simultaneously, because PCE, HCFC-123 and HCFC-124 carry out fluoridation in same reactor, the restriction that influences molecular balance that existed by HCFC-123 and HCFC-124, the transformation efficiency of PCE is relatively low, and temperature of reaction is higher, has aggravated the coking speed of catalyzer.

Summary of the invention

The invention provides a kind of deficiency that exists in the background technology that overcome, make material proportion stablize, be convenient to operation, catalyst life prolongation, comprise the preparation method of the pentafluoride ethane of preparation intermediate product HCFC-123 and HCFC-124.

In order to realize the object of the invention, consider that all there are azeotropism in HCFC-123, HCFC-124 with HF, be difficult to it be separated by distillation tower.If HCFC-123, HCFC-124 are not separated with HF, not only easily cause reactive system material proportion shakiness, and HCFC-123 and HCFC-124 can cause a large amount of HF wastes during as the product extraction.Discover through the contriver, the mixture of HCFC-123, HCFC-124 and HF divides effect fine under suitable temperature mutually, the quality percentage composition of HF in the organic phase is less than 1%, even is lower than 0.3%, inorganic in mutually HCFC-123 and the quality percentage composition of HCFC-124 less than 3%.Therefore, the present invention adopts phase separator that HCFC-123, HCFC-124 are separated with HF, not only solved the reactive system material proportion problem of unstable that background technology exists, and a large amount of HF wastes that cause when having reduced HCFC-123, HCFC-124 as the product extraction.Adopt two fluorination reactors, with PCE and hydrogen fluoride is raw material, first reactor mainly fluoridized the reaction that PCE generates intermediate product HCFC-123, HCFC-124, second reactor mainly fluoridized the reaction that HCFC-123, HCFC-124 generate target product HFC-125, and utilize distillation tower and phase separator effectively to separate the organic intermediate product and the unreacted hydrogen fluoride of different boiling ranges, above-mentioned material is circulated to continues reaction in first fluorination reactor and second fluorination reactor as required.Stablize by controlling the fresh flow realization response system material proportion of adding material and recycle stock, especially the flow of Control Circulation HF.

The invention provides a kind of is the method for feedstock production pentafluoride ethane with PCE and HF, comprises the method for preparing intermediate product HCFC-123 and HCFC-124, and it may further comprise the steps:

A. hydrogen fluoride and zellon enter first reactor, fluoridation takes place in the presence of fluorination catalyst, comprise 2 of reaction generation in the product stream, 2-two chloro-1,1,1-Halothane, 2-chloro-1,1,1,2-Tetrafluoroethane, pentafluoride ethane, hydrogenchloride and unreacted hydrogen fluoride and zellon;

B. the product stream with step a carries out fractionation by distillation, the zellon that contains low amount of fluorinated hydrogen after separating is circulated to first reactor continues reaction;

C. with 2 of fractionation by distillation in the product stream of step a, 2-two chloro-1,1,1-Halothane, 2-chloro-1,1,1,2-Tetrafluoroethane and partially fluorinated hydrogen enter second reactor, continue fluoridation in the presence of fluorination catalyst, comprise pentafluoride ethane, hydrogenchloride and the unreacted hydrogen fluoride, 2 of generation in the product stream of second reactor, 2-two chloro-1,1,1-Halothane, 2-chloro-1,1,1, the 2-Tetrafluoroethane;

D. with step a after separating zellon product stream and the product stream of step c distill, make pentafluoride ethane, hydrogenchloride and hydrogen fluoride, 2,2-two chloro-1,1,1-Halothane and 2-chloro-1,1,1, the separation of 2-Tetrafluoroethane;

E. the isolating pentafluoride ethane of steps d, hydrogenchloride are deacidified, technology such as dehydration, rectifying, obtain the target product pentafluoride ethane;

F. with the isolating hydrogen fluoride of steps d, 2,2-two chloro-1,1,1-Halothane and 2-chloro-1,1,1, the 2-Tetrafluoroethane is separated at-30～60 ℃, is rich in a hydrofluoric inorganic part mutually and is circulated to first reactor, and a part is circulated to second reactor and uses, be rich in 2,2-two chloro-1,1,1-Halothane and 2-chloro-1,1,1, the organic phase of 2-Tetrafluoroethane is circulated to second reactor and further reacts;

G. also can step f is isolated 2,2-two chloro-1,1,1-Halothane, 2-chloro-1,1,1, the 2-Tetrafluoroethane further distills, and obtains 2,2-two chloro-1,1,1-Halothane and 2-chloro-1,1,1,2-Tetrafluoroethane product.

At least a second reactor that enters of HCFC-123, HCFC-124 reacts.

The type of reactor that is used for fluoridation is not crucial, can use tubular reactor, fluidized-bed reactor etc.In addition, adiabatic reactor or isothermal reactor also can be used to the present invention.

In fluoridation, chromic oxide, chromium fluoride, fluorizated chromic oxide, aluminum fluoride, fluorizated aluminum oxide, the known fluorination catalysts such as chromic oxide that are carried on the chromic oxide on gac, aluminum fluoride, the magnesium fluoride and contain multiple metal (as Zn, Co, Ni, Ge, In etc.) all are applicable to the present invention.

To the fluorizated reaction conditions without limits, can suitably select according to catalyst activity levels.Reaction pressure is 0～2.0MPa, preferred 0.5～1.5MPa, more preferably 0.8～1.2MPa.The pressure of first reactor and second reactor can be the same or different.The temperature of reaction of first reactor is 200～400 ℃, preferred 250～350 ℃, and more preferably 280～330 ℃.The temperature of reaction of second reactor is 200～400 ℃, preferred 300～380 ℃, and more preferably 330～350 ℃.The first reactor inlet place, the mol ratio of HF and PCE is preferably 3～15, and more preferably 6～10; The second reactor inlet place, the mol ratio of HF and organic raw material (among HCFC-123 and the HCFC-124 at least a) mixture is preferably 3～10, and more preferably 6～8.In first reactor, can be preferably 5～30 seconds the duration of contact of unstripped gas and catalyzer, more preferably 10～20 seconds; In second reactor, be preferably 1～20 second the duration of contact of unstripped gas and catalyzer, more preferably 5～10 seconds.

Among the present invention, for the HF that controls reactive system and the mol ratio of organic materials, a large amount of HF circulate in reactive system, and fresh HF raw material can or enter reactive system by first reactor, second reactor simultaneously by any one reactor in first reactor, second reactor.

The present invention can suitably select according to the working pressure of the level of equipment, general facilities, reactive system and the isolating composition of desire etc. to the operational condition of distillation tower without limits.Working pressure is 0.2～2.0MPa, preferred 0.5～1.5MPa, more preferably 0.8～1.2MPa.Generally speaking, the working pressure of distillation tower is consistent with reactive system.

Owing to all contain HF, HCFC-123 and HCFC-124 in first reactor and second reactor, therefore, first reactor product stream behind the separation PCE can be separated HCl and HFC-125 with second reactor product stream in same distillation tower, also can separate at different distillation towers.When different distillation towers separate, first reactor product stream is separated at different phase separators with HCFC-123, HCFC-124 with HF in second reactor product stream; When same distillation tower separates, separate at same phase separator.

Divide the phase separation temperature of device to be-30～60 ℃ mutually, preferred-10～40 ℃, more preferably 10～30 ℃.The phase separation temperature that divides device mutually be organism such as HCFC-123, HCFC-124 can with the isolating key of HF, temperature is low more, separating effect is good more.

Description of drawings

Fig. 1 represents the process flow sheet of pentafluoride ethane preparation.

Fig. 2 represents the pentafluoride ethane preparation technology schema of coproduction HCFC-123, HCHC-124.

At Fig. 1, the label meaning in 2 is as follows.Pipeline: 1,2,4,6,7,8,10,11,13,14,15,16,17,18,19,21,22,23,25 and 26; First reactor: 3; Distillation tower: 5,9 and 24; Phase separator: 12; Second reactor: 20.

Embodiment

Embodiment 1:

The present invention is described in more detail with reference to Fig. 1.The mixture of fresh PCE or PCE and HF is through pipeline 1, enter in first reactor 3 that is filled with fluorination catalyst by pipeline 2 with HF logistics that recycles and the PCE logistics that recycles, being 200～400 ℃ in temperature reacts, the reaction product pipeline 4 of flowing through enters distillation tower 5 and separates, the PCE that tower still component contains small amount of H F enters first reactor by pipeline 6 circulations, and cat head component HCFC-123, HCFC-124, HFC-125, HF and HCl enter distillation tower 9 by pipeline 7,8 to be separated.The cat head component of distillation tower 9 is HFC-125 and HCl, enters the product after-treatment system by pipeline 11, can obtain the HFC-125 product by deacidification, dehydration, rectifying; The still component enters phase separator 12 by pipeline 10 and is separated, and the upper strata is the inorganic phase that is rich in HF, and its part enters first reactor by

pipeline

13,14 circulations, and its another part enters second reactor 20 by

pipeline

13,15,17,18 circulations.The lower floor of phase separator 12 is the organic phase that is rich in HCFC-123, HCFC-124, enters second reactor by

pipeline

16,17,18 circulations.HF, the HCFC-123, the HCFC-124 that enter second reactor 20 are under the effect of fluorination catalyst, and in 200～400 ℃ of reactions of temperature, reacting product stream enters distillation tower 9 by pipeline 21,8 to be separated.

The main streams composition sees Table 1 among the embodiment.

Table 1

The pipeline logistics	1	4	6	7	10	11	14	15	16	21
The pipeline logistics	1	4	6	7	10	11	14	15	16	21	HF	90	403		403	1073	2	371	670	32	672
PCE	150	72	72								HF	90	403		403	1073	2	371	670	32	672
PCE	150	72	72								HCFC-123		73		73	280		4	8	268	207
HCFC-124		57		57	244		3	7	234	187	HCFC-123		73		73	280		4	8	268	207
HCFC-124		57		57	244		3	7	234	187	HFC-125		5		5		104				99
CFC-115						1				1	HFC-125		5		5		104				99
CFC-115						1				1	HCl		79		79		133				54
Other		1		1	1				1		HCl		79		79		133				54
Other		1		1	1				1		Total amount (kg/h)	240	690	72	618	1598	240	378	685	535	1220

Embodiment 2:

The present invention is described in more detail with reference to Fig. 2.Figure 2 shows that the pentafluoride ethane preparation method of coproduction HCFC-123, HCHC-124, on pentafluoride ethane preparation method basis shown in Figure 1, increased the distillation tower 24 that separates HCFC-123, HCFC-124.In this case, the organic phase of HCFC-123 and HCFC-124 is rich in the lower floor of phase separator 12, its part is circulated to second reactor 20 by

pipeline

16,22 and reacts, its another part enters distillation tower 24 by

pipeline

16,22 to be separated, tower still component is HCFC-123, and the cat head component is HCFC-124.Isolated HCFC-123 and HCFC-124 enter the product after-treatment system through

pipeline

25 and 26 respectively, by obtaining the finished product after deacidification, dehydration, the rectifying.

The main streams composition sees Table 2 among the embodiment.

Table 2

The pipeline logistics	1	4	6	7	10	11	14	15	16	19	21	23	25	26
The pipeline logistics	1	4	6	7	10	11	14	15	16	19	21	23	25	26	HF		403		403	1073	2	461	580	32	90	672	3	2	1
PCE	150	72	72												HF		403		403	1073	2	461	580	32	90	672	3	2	1
PCE	150	72	72												HCFC-123		73		73	280		4	8	268		207	50	50
HCFC-124		57		57	244		3	7	234		187	46		46	HCFC-123		73		73	280		4	8	268		207	50	50
HCFC-124		57		57	244		3	7	234		187	46		46	HFC-125		5		5		104					99
CFC-115						1					1				HFC-125		5		5		104					99
CFC-115						1					1				HCl		79		79		133					54
Other		1		1	1				1						HCl		79		79		133					54
Other		1		1	1				1						Total amount (kg/h)	150	690	72	618	1598	240	468	595	535	90	1220	99	52	47

Claims

1. the preparation method of a pentafluoride ethane may further comprise the steps:

E. the isolating pentafluoride ethane of steps d, hydrogenchloride are deacidified, dehydration, rectifying, obtain the target product pentafluoride ethane;

F. with the isolating hydrogen fluoride of steps d, 2,2-two chloro-1,1,1-Halothane and 2-chloro-1,1,1, the 2-Tetrafluoroethane is separated at-30～60 ℃, and be rich in a hydrofluoric inorganic part mutually and be circulated to first reactor,

A part is circulated to second reactor and uses, and is rich in 2,2-two chloro-1,1, and 1-Halothane and 2-chloro-1,1,1, the organic phase of 2-Tetrafluoroethane is circulated to second reactor and further reacts;

G. step f is isolated 2,2-two chloro-1,1,1-Halothane, 2-chloro-1,1,1, the 2-Tetrafluoroethane further distills, and obtains 2,2-two chloro-1,1,1-Halothane and 2-chloro-1,1,1,2-Tetrafluoroethane product.

2. pentafluoride ethane preparation method according to claim 1 is characterized in that the described distillation of steps d carries out at different distillation towers.

3. pentafluoride ethane preparation method according to claim 2 is characterized in that the described hydrogen fluoride of step f and 2,2-two chloro-1,1, and 1-Halothane, 2-chloro-1,1,1,2-Tetrafluoroethane are separated and carry out at different phase separators.

4. pentafluoride ethane preparation method according to claim 1 is characterized in that 2,2-two chloro-1,1, and 1-Halothane, 2-chloro-1,1,1, at least a second reactor that enters of 2-Tetrafluoroethane reacts.

5. pentafluoride ethane preparation method according to claim 1 is characterized in that fresh hydrogen fluoride raw material enters first reactor and/or second reactor.

6. pentafluoride ethane preparation method according to claim 1 is characterized in that the described phase separation temperature of step f is-10～40 ℃.

7. pentafluoride ethane preparation method according to claim 1 is characterized in that the described phase separation temperature of step f is 10～30 ℃.