CN1285813A

CN1285813A - Method of production hydrofluorocarbons

Info

Publication number: CN1285813A
Application number: CN98813141A
Authority: CN
Inventors: J·S·巴斯; P·H·谢德勒
Original assignee: AlliedSignal Inc
Current assignee: Honeywell International Inc
Priority date: 1997-11-21
Filing date: 1998-11-23
Publication date: 2001-02-28
Also published as: BR9815103A; KR20010032295A; JP2001524459A; WO1999026906A2; CA2311547A1; EP1034156A2; AU1535099A; WO1999026906A3

Abstract

A process for producing fluorinated organic compounds comprising reacting an organic compound fluorination agent in the presence of a fluorination catalyst, while maintaining a pressure less than sufficient for high-temperature distillation, to produce the desired fluorinated carbon compound.

Description

Produce the method for hydrofluorocarbons

The field of the invention

The present invention relates generally to the preparation method of hydrofluorocarbons and fluorocarbons.More particularly, the present invention relates to the method for catalytic fluorination, the activity that this method has improved the productive rate of required hydrofluorocarbons/fluorocarbons and prolonged used fluorination catalyst.

Background of the present invention

The production method of hydrofluorocarbons (HFCs) and fluorocarbons (FCs) is known in the art.Generally speaking, these production methods comprise fluoridizes to produce required HFC or FC compound chlorinated organic cpd, reclaims required compound by rectifying then.Preferred gas phase catalytic fluorination method in fluorination process.For example, when producing methylene fluoride (HFC-32), with chlorinated organic cpd (for example as methylene dichloride (CH ₂Cl ₂)) and fluorizating agent (for example as hydrogen fluoride (HF)) preheating and in the presence of fluorination catalyst interreaction obtain product stream.

Required HFC or FC compound reclaim from described product stream by using rectification method, and described product stream also contains other material of byproduct of reaction as described.Rectifying is for known in the art, generally includes the rectifying instrument that uses as the circulation post, and this circulation post is operated under certain temperature and pressure, to isolate required compound from product stream.The pressure and temperature of rectifying is inter-related, and therefore high working pressure is usually corresponding to high rectification temperature.The cooling of rectification temperature decision post needs.

Here the purpose in order to discuss, cooling--the high temperature cooling and the subcooling of dividing two kinds of base types.High temperature cooling is meant to be cooled to and is not less than about 0 ℃ temperature.This high temperature cooling can relatively easily and cheaply be finished by using general equipment and refrigeration agent.On the other hand, subcooling refers to be cooled to and is not higher than approximately-15 ℃ temperature.Equipment that subcooling is required and refrigeration agent can be more required than high temperature cooling costliness.Therefore, industrial, more preferably in the pressure range that allows the use high temperature cooling, operate described circulation post, hereinafter referred to as " high temperature rectifying ".

For obtaining suitable product stream flow, described circulation post is lower than at pressure under the pressure of described reactor to be operated.Therefore, consider that the pressure between described reactor and the described circulation post falls, the application of custom is to carry out described reaction under the pressure that allows the rectifying of use high temperature.Foot can easily be measured by the technician in rectifying field in the reaction pressure of carrying out high temperature rectifying.It depends on multiple factor, comprises reactor and the pressure difference of described circulation post, the phase behaviour of required product and the composition of other product stream as described.For example, for the pressure that is fit to of described HFC-32 high temperature rectifying for being higher than about 100psig.

Although use extensivelyr by fluoridizing the prior art method of producing HFCs and FCs with rectifying, they all have several shortcomings.One is the problem of catalyst deactivation in the fluorination process in these bigger shortcomings, and this will cause lower productive rate.In a measure that keeps catalyst activity, usually with regenerator (as chlorine) in reactor as described in reagent is co-fed in a continuous manner.Yet thisly add the formation that chlorine has increased the by product of generally not wanting continuously.

By product makes rectifying become complicated, and can greatly reduce the product productive rate and reduce product quality.For example, in producing HFC-32, the formation of chlorofluoromethane (CFC-12) greatly increases along with the increase of the amount of the chlorine that uses.Regrettably, CFC-12 and HFC-32 have formed a kind of low azeotropic mixture that boils, and required HFC-32 product is difficult to separate from this mixture.For a CFC-12 of every removal, rectifying needs about ten parts HFC-32 to separate from product.Even described volume of industrial production has enough height to regulate such loss, but also there is the problem of processing in the described by product of not wanting.

Therefore, there are needs prepare HFCs and FCs and not have the method for above-mentioned and other shortcoming.The present invention has satisfied this needs.

The description of the present invention and preferred embodiment

The present invention determined to fluoridize/and reaction pressure scope in the fluorinated organic compounds of rectificating method production such as hydrofluorocarbons and fluorocarbons, reduced the passivation of catalyzer and the formation of the by product do not wanted and improved productive rate in this reaction pressure scope.Determined reaction pressure scope is lower than applied traditionally pressure, preferably is lower than the pressure that high temperature rectifying is used always.

Though because the described advantage of high temperature rectifying and produce preferred relative high reaction pressure among HFCs and the FCs at prior art, according to the present invention by using low relatively reaction pressure to realize the significant astonishing reduction effect of catalyst deactivation.Thereby the amount of the required oxygenant of described catalyzer (as chlorine) of regenerating has been reduced.Use more a spot of oxygenant to reduce the formation of the by product of not wanting again, these by products cause low product productive rate, make the problem that rectifying is complicated and existence is handled.Therefore, use " low pressure " of the present invention method to cause the formation of such product stream, promptly its product of producing than " high pressure " method of using prior art flows easier rectifying.This provides high product output, simple rectifying and low by product to form.

In preferred embodiments, the invention provides the method for producing fluorinated organic compounds, this method comprises: (a) under the low relatively reaction pressure of maintenance, the reaction medium that contains at least a fluorizating agent and a kind of organic compound is reacted produce product stream; (b) from described product stream, reclaim required fluorinated organic compounds by rectifying.Each step of these steps all illustrates in greater detail hereinafter.Though for illustrative purposes, concrete consideration is done in the preparation of methylene fluoride, yet be should be appreciated that method of the present invention can be applied to prepare various HFCs and FCs, for example as pentafluoride ethane (HFC-125), 1,1,1,2 Tetrafluoroethanes (HFC-134a) and hexafluoroethane (FC-116).

The reaction medium of Shi Yonging comprises fluorizating agent and organic compound in the method for the invention.

The fluorizating agent that is fit to is included in any material that fluorine can be provided in the described reaction.Preferred fluorizating agent is substantially anhydrous hydrogen fluoride (HF).Exist water will cause the described fluorination catalyst of passivation in the described reaction.Terminology used here " substantially anhydrous " meaning is that hydrogen fluoride contains the water that is less than about 0.05% (weight), and preferably contains the water that is less than about 0.02% (weight).Yet the existence that should be understood that water in the described catalyzer can compensate by increasing catalyst levels.

Described organic compound can be to contain atom that the chlorine of bond with carbon or other can replace by fluorine and/or any compound that contains the saturated carbon-to-carbon unsaturated bond of available fluorine.The organic compound that is fit to comprises as hydrogen cfc (compound that contains carbon, chlorine, fluorine and hydrogen), hydrochlorinate carbon (compound that contains carbon, chlorine and hydrogen), cfc (compound that contains carbon, chlorine and fluorine), chlorination carbon (compound that contains carbon and chlorine) or two or more mixture wherein.In preferred embodiments, described chlorinated organic cpd is methylene dichloride (HCC-30).

Described reaction medium comprises the recycled material that preferably flows back to receipts from described product.If the continuous cycling stream of the high-boiling fraction that will obtain adds in institute's reaction medium, then should use a large amount of excessive fluorizating agents for organic compound in described rectifying.Use the higher mole ratio of fluorizating agent and organic compound will cause higher productive rate and selectivity usually.In addition, use a large amount of excessive fluorizating agents will reduce the passivation rate of catalyzer and cause decomposition less in preheater and vaporizer, particularly be higher than when carrying out under 3 normal atmosphere when described being reflected at.In the production of HFC-32, a large amount of excessive HF also can cause the minimizing of the hydrogen chlorofluoromethane (HCFC-31) that produces and the minimizing of unreacted HCC-30 concentration.Usually, HF pressed about at least 25: 1 to about at least 300: 1 with the ratio (measured as separate the back from product stream at HFC-32) of HCFC-31, preferably about at least 50: 1 to about at least 200: 1, more preferably used to about 150: 1 at least ratio in about at least 75: 1.

Though described reaction medium preferably includes recycled material, also can use new raw material.When described method was moved under circulation not continuously, the fluorizating agent that should offer described reaction capacity was to provide with respect to the fluorine of stoichiometry at least of chlorine in the described chlorinated organic cpd.In described embodiment preferred, wherein use HF and HCC-30, the mol ratio of described HF and HCC-30 is preferably from about 1: 1 to about 10: 1, more preferably from about 1: 1 to about 4: 1.Choose wantonly new HCFC-31 is added in the described reaction medium.

Preheating at least one vaporizer before one or more reactants (containing fluorizating agent and chlorinated organic cpd) being delivered to described reactor when needing.Described term " preheating " refers to vaporization and optional overheated described reactant.The temperature range that preheating is fit to is from about 125 ℃ to about 400 ℃, preferably from about 150 ℃ to about 350 ℃, more preferably from about 175 ℃ to about 275 ℃, also more preferably from about 200 ℃ to about 250 ℃.The described vaporizer of Shi Yonging and other container can adopt suitable corrosion resistant material manufacturing in the method.

Preferably before adding described reagent, described reactor adds fluorination catalyst.Terminology used here " fluorination catalyst " is meant the inorganic metal catalyzer, and this catalyzer can quicken to comprise that fluorine replaces the reaction of the chlorine in the chlorination organic molecule.These fluorination catalysts are known by those skilled in the art.Exemplary catalyzer comprises (infinite): the oxide compound of chromium, copper, aluminium, cobalt, magnesium, manganese, zinc, nickel, iron, oxyhydroxide, halogenide, oxyhalogenide and their inorganic salt, Cr ₂O ₃/ Al ₂O ₃, Cr ₂O ₃/ AlF ₃, Cr ₂O ₃/ carbon, CoCl ₂Cr ₂O ₃/ Al ₂O ₃, NiCl ₂/ Cr ₂O ₃/ Al ₂O ₃, CoCl ₂AlF ₃And NiCl ₂/ AlF ₃In addition, but also the metal catalyst of working load as nickel, cobalt, zinc, iron and copper by chromic oxide, magnesium oxide or alumina load.These chromic oxide/aluminium oxide catalysts are known for people, and as U.S. Patent number 5,155, describe in 082.The preferred chromic oxide that uses commercial obtainable catalyzer.Described chromic oxide should be crystal form or unbodied.The amorphous oxidation chromium of preferred use.

Before the described reagent of adding arrived described reactor, the described catalyzer of method pre-treatment that preferably adopts chemistry and/or physics was to produce reactive site, and it will promote fluoridation.For example described catalyzer can be by being equal to or higher than under the temperature of described fluorination reaction temperature, calcining pre-treatment down at inert gas (as nitrogen).Then, be exposed in the fluorizating agent individually or with as many as about 5 rare gas elementes to about 99% (weight) through the incinerating catalyzer described, the time is under about 200 ℃ to about 450 ℃ about at least one hour.Preferred described catalyzer experienced for the 3rd step again, this step in make oxygenant (as chlorine) with as described in catalyzer contact with its reactivity of further raising.The HF of preferred employing about 60 to about 75% and/or about 20 to about 30% inert gas dilution chlorine.Chlorine can pass through from described catalyzer, and the cumulative volume of chlorine is about 1: 3 with the cumulative volume of catalyzer ratio, and 000, preferably approximately 10: 1,000, more preferably about 50: 500.Exposure duration can be from about 1 to about 200 hours, and preferably approximately 5 is to about 70 hours, more preferably about 10 to about 30 hours.The exposure of chlorine can be carried out under any temperature and pressure of described fluoridation being convenient to.

Described reagent can be separately or is transported in the described reactor as mixture and forms reaction medium.In a single day described reaction is carried out, and then described reagent adds the reagent that continues the required other amount of reaction to provide serially under pressure.

The temperature that described fluoridation is carried out and the time of reaction are depended on raw material, used amount and used catalyzer.Those skilled in the art can easily optimize the condition of described reaction to obtain desired result in this area.Temperature is usually between about 125 ℃ to about 425 ℃, preferably between about 150 ℃ to about 300 ℃, more preferably between about 200 ℃ to about 250 ℃.

Depend on Several Factors duration of contact, comprise as catalyst concn, catalyst type and as described in temperature.Reagent by required time of catalyst bed (supposing the catalytic bed of 100% sky) usually from about 1 to about 120 seconds, preferably from about 2 to 60 seconds, more preferably from about 4 to about 50 seconds, also more preferably from about 5 to about 30 seconds.

As mentioned above, method of the present invention is carried out under than the low relatively pressure of using traditionally, described use traditionally comprise sufficiently high pressure usually to guarantee high temperature rectifying.The required minimal pressure of high temperature rectifying depends on described product stream, more particularly, depends on the low boiler cut of described product stream.Described rectifying pressure should be enough high so that can the described low boiler cut of partial condensation under given temperature.Under the situation of high temperature rectifying, described temperature is higher than about 0 ℃.The used described reaction pressure of method of the present invention preferably is lower than carries out the required pressure of high temperature rectifying.As the required minimum pressure of HFC-32 high temperature rectifying for being higher than about 100psig.

The method according to this invention, described reaction pressure should not be higher than about 135psig usually, more preferably between the extremely about 100psig of about barometric point, also more preferably between the extremely about 80psig of about 20psig, most preferably between the extremely about 75psig of about 40psig.

Method of the present invention can comprise an optional step, in this step oxygenant is added in the described reaction with the described catalyzer of regenerating.The oxygenant that is fit to is known in the art.They comprise as elemental chlorine or oxygen.Described oxygenant can adopt any suitable mode to add, as can with as described in the oxygenant continuously or intermittently add, as with its with as described in reagent mix and when the needs adding to keep catalyst activity.In preferred mode, described oxygenant is periodically added, can reduce described reaction of monitoring and the described oxygenant needs of charging in a continuous manner like this.Perhaps according to prior art, by periodically stopping the described catalyzer of described reaction regeneration keeps activity of such catalysts.Because described catalyzer can not be passivated soon under working pressure of the present invention, thus described reactor shutdowns need be than the much less that carries out under the technological operation condition is formerly arranged.

As mentioned above, carry out described reaction by the pressure by its regulation, described catalyzer under high pressure carries out described reaction such as fruit can be kept its activity the longer time.Therefore, can use the catalyzer of reduction.This formation that undesirable by product has been described reduces.For example produce under the top condition of HFC-32 at described high pressure, the amount of the CFC-12 that finds in the low cut that boils is usually above about 500ppm.When using method of the present invention, the amount of corresponding C FC-12 greatly reduces.The concentration of CFC-12 is less than about 250ppm under preferred pressure, be less than about 100ppm under preferred pressure, also is being less than about 50ppm under the preferred pressure.

Required HFC or FC compound adopt equipment and technology commonly used to reclaim from described reaction mixture.In described embodiment preferred, described product stream is separated into low boiling and high-boiling fraction, required then compound reclaims from their cuts separately.For example, in the production of methylene fluoride, described product stream may also include HCFC-31 and HCl and unreacted raw material such as HF and HCC-30.This product stream is delivered to described circulation post to be separated.Described high-boiling fraction or the bottom current that comes out from stripping tower contains unreacted HF, HCC-31 and intermediate reactant HCFC-31.This mixture preferred cycle is to described reactor as mentioned above.To contain described low the boil cut or the upper stream recovery of methylene fluoride, HCl, HF and byproduct of reaction.

Perhaps, described fraction separation can be undertaken by two steps.In the first step, with described product flow quenching, even the temperature of described product stream is reduced to it below dew point.Quenching can be carried out in the packed column that contains any suitable anticorrosive packing material and the phegma that is fit to such as HF, HCC-30 and/or HCFC-31.The product of described quenching is delivered into the circulation post subsequently.

The product of basic purifying reclaims from the described low cut that boils by any suitable method.Described recovery is preferably carried out step by step by a series of, is included in and handles described gas phase mixture under the condition that is suitable for removing HCl and trace HF in the HCl distillation column or in the HCl aqueous solution absorption tower.Described then crude product (as methylene fluoride) carries out neutralization reaction and forms under the condition of neutralized reaction product and handle carrying out residual acidity in first caustic scrubber.Usually, described caustic scrubber contains water, sodium hydroxide or potassium hydroxide.Then, handle described neutralized reaction product removing residual chlorine effectively and form under the condition of not chloride product substantially in second caustic scrubber, this laveur preferably contains sodium hydroxide and sulphite, for example S-WAT.The product that will be substantially free of chlorine is then handled with the sulfuric acid laveur, uses solid drier such as any suitable commercial obtainable molecular sieve subsequently, and this siccative can absorb residual moisture content and form water-free substantially product from the gas stream that contains product.At last, be enough to remove residual impurity and produce under pure substantially product (being higher than 99.97% (weight) as the methylene fluoride) condition will be substantially not the product of water content import by a plurality of rectifying columns.Any as mentioned above residual HCFC-31 that removes in this final step can be recycled.Under the situation of producing methylene fluoride, the minimizing of CFC-12, and the minimizing of CFC-12/HFC-32 azeotropic mixture thus makes above-mentioned rectification step reduce to minimum.

Embodiment

Embodiment described below is explanation enforcement of the present invention.More particularly, these embodiment describe the low pressure method of producing methylene fluoride, and wherein the formation of the passivation of catalyzer and undesirable by product has reduced with respect to the result who uses high pressure method to obtain.

Embodiment 1

The present embodiment explanation is kept the activity that the low relatively pressure of described reactor has prolonged described fluorination catalyst in producing described methylene fluoride.At diameter is to add the 4L chromium oxide catalyst in 4 Monel metal 400 reactors, and this catalyzer has carried out following preprocessing process.With described catalyzer under 30 ℃, the nitrogen flow of per minute 20 standard liters (slpm) dry 8 hours.With described catalyzer by being to be added in the nitrogen that flow velocity is 0.21b/h in 250 ℃ the reactor, with HF to regulate (condition) in temperature.Make the HF flow velocity bring up to 11b/h, stoping the excess catalyst heat release, it will cause " scorching hot " phenomenon of knowing under so enough low speed.Make temperature little by little be elevated to 350 ℃ and keep 4h then.Make the temperature of described catalyst bed be reduced to 250 ℃ subsequently, chlorine is introduced HF/N with the speed of per minute 500 standard cubic centimeters (sccm) ₂In the mixture, the time length is 24h.

After this pre-treatment step, stop described chlorine and nitrogen gas stream, HCC-30 and HF are mixed be incorporated in 185 ℃ and pass through preheater.As illustrated in following table 1, the HCC-30 of vaporization and HF mixture are transported in the described reactor that maintains under the predetermined pressure.The effluent of described reactor uses heat exchanger to quench and be delivered to pressure and maintains in the circulation post that is lower than under the described reactor pressure 5-10psig.Described low rectifying composition (HCFC-31, HF and the HCC-30) circulation of boiling is mixed with new HF and HCC-30 incoming flow, and be that 4lb/in is delivered to described preheater and reactor with the flow velocity.New HF and the feeding rate of HCC-30 maintain 0.6 and 1.2lb/in respectively.

As illustrated in following table 1, described experimental procedure is included under the different pressures reacts.For 45 and 75psig under experiment for, chlorine speed with 200sccm in 6-8 hour of keeping the catalyst activity sexual needs joins in the described incoming mixture.When under 135psig, operating, chlorine is added 300-400g can recover the requirement adding of catalyst activity to aforementioned levels, to be generally in 6h.The transformation efficiency of the HCC-30 that obtains is 85-95%.Transformation efficiency drops to 60% suddenly and shows that needs add chlorine to recover transformation efficiency to previous level.Under the more low pressure of the inventive method, find requiring to add the time that chlorine keeps between the catalyst activity has increased surprisingly.This is shown in the following table 1.

The adding of table 1-chlorine

Reactor pressure (psig) adds the time (hrs) between the chlorine

45 100

75 60

135 20

Embodiment 2

The formation that the low relatively pressure of described reactor can reduce the described low by product that boils is kept in the present embodiment explanation in the production of methylene fluoride.The different pressure that uses in simultaneous test is determined in following table 2.Other reaction conditions is as describing in embodiment 1.Isolating described hanging down boiled composition (HCl and HFC-32) by containing the caustic scrubber of 10%KOH in described rectifying column, removes HCl here.Drying is also collected crude product HFC-32 product.

The low by product that boils that can form in reaction in addition is CFC-12, HCFC-22 and HFC-23.These by products are represented great production loss, particularly CFC-12, and itself and HFC-32 form azeotropic mixture.As shown in the following table 2, find that surprisingly the formation speed of these by products improves along with the increase of reactor pressure.The concentration of described by product is represented with every ppm part (ppm) of methylene fluoride (HFC-32) in the thick product.Elution time, (time on stream) was to represent with the hours of operating under specified pressure.

Table 2

The low by product that boils

Pressure elution time CFC-12 HCFC-22 HFC-23

(psig) (h) (ppm) (ppm) (ppm)

45 260 n．d. n.d. n．d．

75 240 n．d． n．d． n．d．

75 977 19 102 1497

135 577 654 2815 2816n.d.=do not detect, and detect to be limited to 1ppm.

As shown in the last table 2, the described low by product that boils just is being observed after through the extremely long elution time under the low pressure (45 and 75psig), and under high pressure (135psig), they are observed immediately on high level.

Embodiment 3

Described reactor is kept in present embodiment explanation in the production of methylene fluoride can reduce the boil formation of by product of described height at low relatively pressure.The different pressures that uses in described simultaneous test is determined in following table 3.Other reaction conditions is as describing in embodiment 1.The height by product that boils forms in the method.Height boil example such as the methyl chloride (HCC40) and the HCFC-21 of by product.Though these materials and unreacted HF, HCC-30 and HCFC-31 are recycled described reactor, yet they represent great production loss.And HCC-40 can react with HFC-41 very lentamente, therefore gathers in described cycling stream, needs periodically to stop work to clean described system.Find that surprisingly the boil formation speed of by product of these height increases along with the increase of reactor pressure, as shown in the following table 3.Described concentration is that the weight percent with all organic concentration in the described cycling stream provides.

The table 3 height by product that boils

Pressure elution time HCC-40 HCFC-21

(psig) (h) (wt％) (wt％)

45 260 n.d. n．d.

75 914 n.d. n.d.

135 180 0.23 n.d.

135 582 0.64 n.d.

135 703 0.97 1.34 as shown in the last table 3, the described height by product that boils be not detected after through the extremely long elution time under the low pressure (45 and 75psig), yet under high pressure (135psig), HCC-40 was observed through the short relatively time, was observed after the time of HCFC-21 process than length.

Claims

1. produce the method for fluorinated organic compounds, this method comprises: be not enough under the pressure of high temperature rectifying in maintenance, the reaction of organifying compound and fluorizating agent is to produce product stream in the presence of fluorination catalyst; With from described product stream, reclaim described fluorinated organic compounds by low temperature fractionation.

2. the process of claim 1 wherein that described reaction pressure remains on is not higher than about 100psig.

3. the method for claim 2, wherein said reaction pressure remains between about 20 to about 80psig.

4. the method for claim 3, wherein said reaction pressure remains between about 40 to about 75psig, and described low temperature fractionation is carried out under not being higher than approximately-15 ℃.

5. the method for claim 1, it also comprises periodically makes described catalyzer contact with oxygenant.

6. produce the method for fluorinated organic compounds, this method comprises: keeping not being higher than under the pressure of about 135psig organifying compound and fluorizating agent reaction production product stream in the presence of fluorination catalyst; With from described product stream, reclaim described fluorinated organic compounds by rectifying.

7. the method for claim 6, wherein said reaction pressure remain on about normal pressure to approximately between the 100psig.

8. the method for claim 7, wherein said reaction pressure remains between about 20 to about 80psig.

9. produce the method for methylene fluoride, this method comprises: be not enough under the pressure of high temperature rectifying in maintenance, make methylene dichloride steam and hydrogen fluoride steam reaction produce product stream in the presence of fluorination catalyst; Receive described methylene fluoride with flowing back to from described product by low temperature fractionation.

10. the method for claim 9, wherein said reaction pressure remains on and is not higher than about 100psig.

11. the method for claim 10, wherein said reaction pressure remain between about 20 to about 80psig.

12. the method for claim 11, wherein said reaction pressure remain between about 40 to about 75psig.

13. the method for claim 9, it also comprises periodically makes described catalyzer contact with oxygenant.

14. produce the method for methylene fluoride, the step that this method comprises is: keeping that the CFC-12 concentration of described low boiler cut is not higher than under the reaction pressure of about 500ppm, making methylene dichloride and hydrogen fluoride reaction produce product stream in the reactor of fluorination catalyst is housed; Reclaim high-boiling fraction and the low cut that boils by rectifying from described product stream, the described low cut that boils contains methylene fluoride; With the described methylene fluoride of recovery from the described low cut that boils.

15. remaining on the CFC-12 concentration that makes described low boiler cut, the method for claim 14, wherein said reactor pressure be not higher than about 100ppm.

16. remaining on the CFC-12 concentration that makes described low boiler cut, the method for claim 15, wherein said reactor pressure be not higher than about 50ppm.

17. remaining on pressure, the method for claim 16, wherein said reactor be not higher than under about 100psig and temperature be not higher than approximately-15 ℃.

18. in reaction, keep the active method of described fluorination catalyst, wherein come synthesis of fluorinated carbon compounds and from this product stream, reclaim described fluorinated carbon compounds by rectifying by making chlorinated organic cpd and fluorizating agent in the reactor of described fluorination catalyst is housed, react generation product stream; Described method comprises: keep described reactor under the pressure that is not enough to high temperature rectifying.

19. the method for claim 14, wherein said reactor pressure remain on about normal pressure to approximately between the 100psig.

20. the method for claim 15, wherein said reactor pressure remain between about 20 to about 80psig.