CN103319303B - Method for simultaneously preparing 1,1,1,2-tetrafluoroethane and difluoromethane - Google Patents
Method for simultaneously preparing 1,1,1,2-tetrafluoroethane and difluoromethane Download PDFInfo
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Abstract
The invention discloses a method for simultaneously preparing 1,1,1,2-tetrafluoroethane (HFC-134a) and difluoromethane (HFC-32). 1,1,1,2-tetrafluoroethane and difluoromethane are simultaneously prepared through the gas-phase fluorination catalysis of a one-step reaction of raw materials comprising 1,1,1-trifluoro-2-chloroethane (HCFC-133a), dichloromethane (HCC-30) and anhydrous hydrogen fluoride (AHF). The method has the advantages of simple process, high yield, good selectivity, small equipment investment and low energy consumption.
Description
Technical field
The present invention relates to the preparation method of fluorocarbon (HFC).Specifically, a kind of method simultaneously preparing HFA 134a and methylene fluoride is related to.
Background technology
Methylene fluoride, ODP value is 0, and GWP value is 0.12, and it has good environmental-protecting performance, is generally made into the mixing mediums such as R407, R410 from other HFC series products by the different mixing of component concentration and uses.
Methylene fluoride is industrial two kinds of production methods:
1., under antimony-based catalyst exists, carry out liquid-phase fluorination with HF and methylene dichloride.
2., under chromium-based catalysts exists, carry out gas phase fluorination with HF and methylene dichloride.
Prior art industrialized unit majority adopts the operational path of liquid-phase fluorination, and this technological line exists the shortcomings such as equipment corrosion, and gas phase fluorination is high due to temperature, causes energy consumption high, but gas phase fluorination can long period continuous seepage, and catalyst life is longer.
1,1,1,2-Tetrafluoroethane is suitability for industrialized production comprehensively, in order to the methyl chlorofluoride (F12) in alternative home freezer and automative air conditioning, 1,1,1, the industrial gaseous fluoridizing method generally adopting 1,1,1-trifluoro-2-chloroethane of production method of 2-Tetrafluoroethane, the method catalyst life is long, can continuous seepage.
Because produce methylene fluoride and 1,1,1, the industrialized unit facility investment of 2-Tetrafluoroethane is large, and running cost is high, and produces methylene fluoride and 1 simultaneously, the multipurpose plant facility investment of 1,1,2-Tetrafluoroethane is few, the quantum of output of two kinds of products can be adjusted flexibly, device turndown ratio is large, therefore prepares methylene fluoride and 1,1 simultaneously, the technology of 1,2-Tetrafluoroethane becomes the focus of research.
As Chinese patent notification number CN1067042C, the June 13 calendar year 2001 day for announcing, denomination of invention: the method simultaneously preparing methylene fluoride and HFA 134a.This invention in gas phase with without any under the existence of catalyzer, temperature more than 500 DEG C, when having hydrogen to exist, prepare methylene fluoride and 1 by pyrolysis monochlorodifluoromethane (F22) simultaneously, 1,1,2-Tetrafluoroethane, this invention service temperature is high, the content of by product F134 is higher, methylene fluoride and 1,1, the selectivity of 1,2-Tetrafluoroethane is lower.
China Patent Publication No. CN1142220A, publication date on February 5th, 1997, denomination of invention: the preparation method of methylene fluoride and HFA 134a.This invention adopts two or more reactor to prepare methylene fluoride and HFA 134a simultaneously, and the first reactor makes methylene dichloride and trieline (TCE) and anhydrous hydrogen fluoride (AHF) react to prepare methylene fluoride and 1,1,1-trifluoro-2-chloroethane; In one or more reactor, make unreacted methylene dichloride and AHF react content to reduce methylene dichloride as far as possible again, through being separated methylene fluoride, 1,1,1, after 2-Tetrafluoroethane, AHF, then in other reactor, make 1,1,1-trifluoro-2-chloroethane and AHF react production 1,1,1,2-Tetrafluoroethane, then enters the first reactor and reacts by reactant.Weak point is complex process, and facility investment is high, and because the first temperature of reactor is lower than other reactor, turns back to 1 of the first reactor, the low conversion rate of 1,1-trifluoro-2-chloroethane, so a large amount of 1,1,1-trifluoro-2-chloroethane circulates in systems in which, and energy consumption is higher.
Summary of the invention
The present invention is directed to the deficiencies in the prior art, provide that a kind of technique is simple, yield is high, selectivity is good, energy consumption is low, facility investment little while prepare the method for HFA 134a and methylene fluoride.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is: a kind of method simultaneously preparing HFA 134a and methylene fluoride, comprises the following steps:
(1) by 1,1,1-trifluoro-2-chloroethane, methylene dichloride and anhydrous hydrogen fluoride are sent in reactor, under chromium-based fluorination catalyst exists, carry out gas phase fluorination catalyzed reaction, described temperature of reaction is 280 ~ 400 DEG C, and reaction pressure is 0.1 ~ 1.0MPa, anhydrous hydrogen fluoride and 1, the mol ratio of 1,1-trifluoro-2-chloroethane and methylene dichloride total amount is 10 ~ 50:1, and air speed is 800 ~ 2000h
-1, obtain reaction product.
(2) reaction product is sent into after the first knockout tower is separated HCl and obtain the first separated product;
(3) the first separated product is sent into the second knockout tower to be separated, obtain the second separated product and tower bottoms;
(4) namely the second separated product is dry, rectifying obtain HFA 134a and methylene fluoride respectively.
Further:
Described temperature of reaction is preferably 320 ~ 350 DEG C.
Described reaction pressure is preferably 0.3 ~ 0.7MPa.
Described air speed is preferably 800 ~ 1000h
-1.
The mol ratio of described anhydrous hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane and methylene dichloride total amount is preferably 20 ~ 25:1.
The preferred reaction parameter of step of the present invention (1) is combined as: temperature of reaction is 320 ~ 350 DEG C, reaction pressure is 0.3 ~ 0.7MPa, anhydrous hydrogen fluoride and 1,1, the mol ratio of 1-trifluoro-2-chloroethane and methylene dichloride total amount is 20 ~ 25:1, and air speed is 800 ~ 1000h
-1.
The tower bottoms that in the present invention, the second knockout tower obtains is capable of circulation to be proceeded to react to reactor.
The present invention chromium-based fluorination catalyst exist under, with 1,1,1-trifluoro-2-chloroethane (HCFC-133a), methylene dichloride (HCC-30) and anhydrous hydrogen fluoride (AHF) are raw material, 1 can be produced, 1,1 by the reaction of gas phase fluorination catalytic one-stage simultaneously, 2-Tetrafluoroethane (HFC-134a) and methylene fluoride (HFC-32), through conventional lock out operation as obtained 1,1,1 respectively after the unit operations such as depickling, drying, rectifying, 2-Tetrafluoroethane and methylene fluoride product, chemical equation is as follows:
CF
3CH
2Cl+HF→CF
3CH
2F+HCl (1)
CH
2Cl
2+HF→CH
2ClF+HCl (2)
CH
2ClF+HF→CH
2F
2+HCl (3)
According to above formula reaction, reaction (2) generates CH
2clF, it is an intermediate product, under the residence-time conditions that temperature is higher and longer, can change into CH
2f
2, have a small amount of unreacted CH completely
2clF Returning reactor proceeds reaction.
Temperature of reaction has impact to the transformation efficiency of raw material and the selectivity of product.The selectivity of HCFC-133a and HCC-30 transformation efficiency and HFC-134a and HFC-32, changes to some extent along with the rising of temperature of reaction.Temperature is higher, HCFC-133a and HCC-30 transformation efficiency rises, but the selectivity of HFC-134a and HFC-32 can decline.Temperature of reaction is lower, HCFC-133a and HCC-30 transformation efficiency reduces, but the selectivity of HFC-134a and HFC-32 can improve.Therefore, the temperature of reaction in the present invention controls at 280 ~ 400 DEG C, is preferably 320 ~ 350 DEG C.
The mol ratio of anhydrous hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane and methylene dichloride total amount is larger, the trend that feed stock conversion and selectivity are improved.For exchange chloride for fluoride, increase the generation that AHF concentration is conducive to conversion and product; Meanwhile, the mol ratio of anhydrous hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane and methylene dichloride total amount is larger, and the induction time of catalyzer is also shorter, can life-span of extending catalyst.But the mol ratio of anhydrous hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane and methylene dichloride total amount is too large, and aftertreatment load is large, energy consumption is high.Therefore, the mol ratio of the anhydrous hydrogen fluoride in the present invention and 1,1,1-trifluoro-2-chloroethane and methylene dichloride total amount is 10 ~ 50:1, is preferably 20 ~ 25:1.
Feed stock conversion and selectivity decline to some extent with the increase of air speed.Because air speed is larger, the duration of contact of HCFC-133a, HCC-30, AHF and catalyzer is shorter; Meanwhile, also can be increased by the organic materials of catalyst surface in the unit time, easy carbon distribution, affects the work-ing life of catalyzer, though can reduce carbon distribution when air speed is less, the space-time yield of catalyzer now also greatly reduces.Comprehensive above-mentioned situation, the air speed in the present invention is 800 ~ 2000h
-1, be preferably 800 ~ 1000h
-1.
The factor of impact reaction is except temperature, material ratio and air speed, and reaction pressure is also one of important influence factor.The reaction that this reaction reduces for volume, increase pressure contributes to reaction and moves towards positive dirction, accelerates the formation speed of HFC-134a, HFC-32; Meanwhile, improve pressure and can make increase the duration of contact of reaction mass and catalyzer, be conducive to improving transformation efficiency and selectivity.But pressure is too large, require high to reactor material, facility investment increases.Therefore the reaction pressure in the present invention controls at 0.1 ~ 1MPa, is preferably 0.3 ~ 0.7MPa.
In the present invention, do not limit the catalyzer of fluoridation, fluorination catalyst known in the art all can be used for the present invention, such as; Chromic oxide, chromium fluoride, fluorinated chromium, aluminum fluoride, fluorided alumina, the chromic oxide etc. be carried on aluminum fluoride, gac, magnesium fluoride, preferably with chromium-based catalysts.This chromium-based catalysts can adopt coprecipitation method well known in the art to prepare, such as: in proportion chromic salts and auxiliary salt are mixed with certain density solution, add precipitation agent reaction, slurries after filtration, washing, oven dry, roasting, then compression molding, loading reactor, passes into anhydrous HF and nitrogen carries out fluoridizing obtained catalyzer.
In the present invention, the reactor for fluoridation can adopt tubular reactor, fixed-bed reactor etc. multi-form.
In the present invention, the form of knockout tower and operational condition are not limited, appropriate selection can be carried out according to the operational condition etc. of the component be separated and reactive system, such as: the product that reaction can be generated is separated HCl by entering the first knockout tower dry method after compression, and the second knockout tower can adopt rectifying tower to operate, rectifying tower tower top temperature, bottom temperature are made up of rectifying tower working pressure and material and decide.
Compared with prior art, the present invention has the following advantages:
1, technique is simple, yield is high, and selectivity is good, and HCFC-133a transformation efficiency reaches as high as 32.5%, HCC-30 transformation efficiency and reaches as high as 98.9%; HFA 134a selectivity is up to 99.7%, and methylene fluoride selectivity is up to 99.8%;
2, facility investment is little, and energy consumption is low, achieves prepare HFA 134a and methylene fluoride simultaneously in a reactor, and product separation is purified simple.
Accompanying drawing explanation
Fig. 1 is process flow sheet of the present invention.
As shown in the figure: 1 is vaporizer, 2 is reactor, and 3 is compression pump, and 4 is the first knockout tower, and 5 is the second knockout tower, and 6,7,8,9,10,11 is pipeline.
Embodiment
As shown in Figure 1, HCC-30, HCFC-133a and AHF, after pipeline 11 is heat vaporized by vaporizer 1, is entered by pipeline 6 and fluorination catalyst, size are housed flow process of the present invention
material 316L reactor 2 react, reaction product containing HCFC-133a, HFC-32, HFC-134a, a small amount of HCC-30, hydrogenchloride and unreacted HF enters the first knockout tower 4 dry method and is separated HCl after the compressed pump 3 of pipeline 7 compresses, first knockout tower 4 tower top isolates HCl, and refinement treatment obtains hydrochloric acid separately.The material of the first knockout tower 4 tower reactor enters the second knockout tower 5 through pipeline 8, second knockout tower 5 tower top isolates HFC-32 and HFC-134a, drying, rectifying can obtain object product HFC-134a and HFC-32, second knockout tower 5 tower bottoms component is HCFC-133a, a small amount of HCC-30, HF, is circulated to reactor 2 proceeds reaction through pipeline 9.
Below by embodiment, the present invention is described in further detail, but the present invention is not limited to described embodiment.
Embodiment 1 ~ 26
The chromium-based catalysts of 150ml compressing tablet is loaded reactor, be warmed up to 350 DEG C, pass into nitrogen drying 6 hours, then 260 DEG C are cooled to, pass into the anhydrous hydrogen fluoride with nitrogen dilution, carry out activation treatment, due to first time logical anhydrous hydrogen fluoride, reactor bed focus is comparatively obvious, and the focus being controlled beds by the amount of nitrogen does not exceed 380 DEG C, activate after 4 hours, temperature of reactor is raised to 350 DEG C, closes nitrogen and activate, the outlet of question response device no longer includes water vapour and overflows, catalyst activation completes, and whole reactivation process needs 48 hours.
Temperature of reactor is adjusted to temperature of reaction, vaporizer is passed into by after HCC-30, HCFC-133a and anhydrous hydrogen fluoride mixing, gasification is reacted to a little less than entering reactor after temperature of reactor, temperature, pressure, mol ratio and air speed that adjustment is reacted are reacted respectively, and reaction result is in table 1.
Table 1 embodiment 1 ~ 26 reaction result
Claims (2)
1. prepare a method for HFA 134a and methylene fluoride simultaneously, it is characterized in that comprising the following steps:
(1) by 1,1,1-trifluoro-2-chloroethane, methylene dichloride and anhydrous hydrogen fluoride are sent in reactor, under chromium-based fluorination catalyst exists, carry out gas phase fluorination catalyzed reaction, described temperature of reaction is 320 ~ 350 DEG C, and reaction pressure is 0.3 ~ 0.7MPa, anhydrous hydrogen fluoride and 1, the mol ratio of 1,1-trifluoro-2-chloroethane and methylene dichloride total amount is 20 ~ 25:1, and air speed is 800 ~ 1000h
-1, obtain reaction product;
(2) reaction product is sent into after the first knockout tower is separated HCl and obtain the first separated product;
(3) the first separated product is sent into the second knockout tower to be separated, obtain the second separated product and tower bottoms;
(4) namely the second separated product is dry, rectifying obtain HFA 134a and methylene fluoride respectively.
2. the method simultaneously preparing HFA 134a and methylene fluoride according to claim 1, is characterized in that the tower bottoms that the second knockout tower obtains being circulated to reactor proceeds reaction.
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| JP6806174B2 (en) * | 2019-02-19 | 2021-01-06 | ダイキン工業株式会社 | Method for producing 1,1,2-trifluoroethane (HFC-143) |
| CN112047803B (en) * | 2020-08-06 | 2022-07-15 | 浙江衢化氟化学有限公司 | Method for synthesizing difluoromethane by gas phase catalysis |
| CN112125777B (en) * | 2020-08-27 | 2022-06-03 | 浙江衢化氟化学有限公司 | Method for coproducing hydrofluorocarbons |
| CN112409126A (en) * | 2020-12-01 | 2021-02-26 | 山东华安新材料有限公司 | Preparation method of 1, 1, 2, 2-tetrafluoroethane |
| CN113499741A (en) * | 2021-08-10 | 2021-10-15 | 聊城氟尔新材料科技有限公司 | Difluoromethane reaction gas separation device and method and application thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1142220A (en) * | 1993-12-09 | 1997-02-05 | 大金工业株式会社 | Process for producing difluoromethane and 1,1,1,2-tetrafluoroethane |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1142220A (en) * | 1993-12-09 | 1997-02-05 | 大金工业株式会社 | Process for producing difluoromethane and 1,1,1,2-tetrafluoroethane |
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Effective date of registration: 20181122 Address after: 324004 Juhua Group Co., Ltd. Kecheng District, Quzhou City, Zhejiang Province Co-patentee after: Zhejiang Quzhou Juxin Fluorine Chemical Co.,Ltd. Patentee after: Fluoro-Chemial Co., Ltd., Quzhou, Zhejiang Prov Co-patentee after: Zhejiang Engineering Design Co., Ltd. Address before: 324004 Juhua Group, Quzhou City, Zhejiang Province Patentee before: Fluoro-Chemial Co., Ltd., Quzhou, Zhejiang Prov |