U.S. patent application number 15/624338 was filed with the patent office on 2017-10-05 for process for producing 2,3,3,3-tetrafluoropropene.
This patent application is currently assigned to Honeywell International, Inc.. The applicant listed for this patent is Honeywell International, Inc.. Invention is credited to Selma BEKTESEVIC, Hsueh SUNG TUNG, Haiyou WANG.
Application Number | 20170283348 15/624338 |
Document ID | / |
Family ID | 51530205 |
Filed Date | 2017-10-05 |
United States Patent
Application |
20170283348 |
Kind Code |
A1 |
WANG; Haiyou ; et
al. |
October 5, 2017 |
PROCESS FOR PRODUCING 2,3,3,3-TETRAFLUOROPROPENE
Abstract
The invention relates to a process to prepare
2-chloro-3,3,3-trifluoropropene (HCO-1233xf) or
2-chloro-1,1,12-tetrafluoropropane (HCFC-244bb) using
dichloro-trifluoropropanes and/or trichloro-difluoropropanes, and
to prepare 2-chloro-3,3,3-trifluoropropene (HCO-1233xf) using
various 242 and 243 isomers.
Inventors: |
WANG; Haiyou; (Amherst,
NY) ; SUNG TUNG; Hsueh; (Getzville, NY) ;
BEKTESEVIC; Selma; (Williamsville, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Honeywell International, Inc. |
MORRISTOWN |
NJ |
US |
|
|
Assignee: |
Honeywell International,
Inc.
MORRISTOWN
NJ
|
Family ID: |
51530205 |
Appl. No.: |
15/624338 |
Filed: |
June 15, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15190828 |
Jun 23, 2016 |
9701599 |
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15624338 |
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14204054 |
Mar 11, 2014 |
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15190828 |
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61792769 |
Mar 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J 23/745 20130101;
B01J 23/75 20130101; C07C 17/087 20130101; C07C 19/10 20130101;
C07C 19/10 20130101; C07C 21/18 20130101; B01J 27/128 20130101;
C07C 17/25 20130101; B01J 23/26 20130101; Y02P 20/582 20151101;
B01J 27/125 20130101; B01J 27/10 20130101; C07C 17/206 20130101;
C07C 17/25 20130101; C07C 17/087 20130101; C07C 17/206 20130101;
B01J 23/755 20130101 |
International
Class: |
C07C 17/087 20060101
C07C017/087; B01J 27/128 20060101 B01J027/128; B01J 27/10 20060101
B01J027/10; B01J 23/755 20060101 B01J023/755; B01J 23/75 20060101
B01J023/75; C07C 21/18 20060101 C07C021/18; B01J 27/125 20060101
B01J027/125; B01J 23/26 20060101 B01J023/26; B01J 23/745 20060101
B01J023/745; C07C 19/10 20060101 C07C019/10; C07C 17/25 20060101
C07C017/25; C07C 17/20 20060101 C07C017/20 |
Claims
1.-8. (canceled)
9. A process to prepare 2-chloro-3,3,3-trifluoropropene
(HCO-1233xt) and 2-chloro-1,1,1,2-tetrafluoropropane (244bb)
comprising a contacting step comprising contacting at least one
compound of Formulae (I), (II), (III) CX.sub.2.dbd.CCl--CH.sub.2X
(I) CX.sub.3--CCl.dbd.CH.sub.2 (II) CX.sub.3--CHCl--CH.sub.2X (III)
wherein X is independently selected from F, Cl, Br, and I, provided
that at least one X is not fluorine, with anhydrous hydrogen
fluoride (HF) in the presence of a catalyst under conditions
effective to form a composition comprising HCO-1233xf and a
by-product selected from the group consisting of a
dichloro-trifluoropropane, a trichloro-difluoropropane and
combinations thereof; recovering the by-product from the
composition; recycling the by-product to the contacting step
wherein the by-product is converted to
2-chloro-1,1,1,2-tetrafluoropropane (244bb).
10. The process of claim 9 wherein the recovering step comprises
phase separation and distillation.
11. The process of claim 9 wherein the catalyst is selected from
the group consisting of Cr.sub.2O.sub.3, FeCl.sub.3/C,
Cr.sub.2O.sub.3/Al.sub.2O.sub.3, Cr.sub.2O.sub.3/AlF.sub.3,
Cr.sub.2O.sub.3/carbon, CoCl.sub.2/Cr.sub.2O.sub.3/Al.sub.2O.sub.3,
NiCl.sub.2/Cr.sub.2O.sub.3/Al.sub.2O.sub.3, CoCl.sub.2/AlF.sub.3,
NiCl.sub.2/AlF.sub.3 and combinations thereof.
12. The process of claim 9 wherein the dichloro-trifluoropropane is
selected from the group consisting of
2,2-dichloro-1,1,1-trifluoropropane (HCFC-243ab),
1,2-dichloro-1,1,2-trifluoropropane (HCFC-243bc), and combinations
thereof.
13. The process of claim 9 wherein the trichloro-difluoropropane is
selected from the group consisting of
1,2,2-trichloro-1,1-difluoropropane (HCFC-242ac),
1,1,2-trichloro-1,2-difluoropropane (HCFC-242bc), and combinations
thereof.
14. A process to prepare 2-chloro-3,3,3-trifluoropropene
(HCO-1233xf) comprising contacting
1,1,1-trifluoro-2,2-dichloropropane (243ab) with a
dehydrochlorination catalyst under conditions effective to form
1233xf.
15. The process of claim 14 wherein the dehydrochlorination
catalyst is selected from the group consisting of carbon solids,
metal halides, halogenated metal oxides, zero metals and
combinations thereof.
16. (canceled)
17. A process to prepare 2-chloro-3,3,3-trifluoropropene
(HCO-1233xf) comprising contacting at least one compound selected
from the group consisting of 2,2-dichloro-1,1,1-trifluoropropane
(HCFC-243ab), 1,2-dichloro-1,1,2-trifluoropropane (HCFC-243bc),
1,2,2-trichloro-1,1-difluoropropane (HCFC-242ac), and
1,2-dichloro-1,1,2-trifluoropropane (HCFC-243bc) in the presence of
HF under conditions effective to form (HCO-1233xf).
18. The process of claim 17 wherein the conditions effective
include the presence of a catalyst selected from the group
consisting of Cr.sub.2O.sub.3, FeCl.sub.3/C,
Cr.sub.2O.sub.3/Al.sub.2O.sub.3, Cr.sub.2O.sub.3/AlF.sub.3,
Cr.sub.2O.sub.3/carbon, CoCl.sub.2/Cr.sub.2O.sub.3/Al.sub.2O.sub.3,
NiCl.sub.2/Cr.sub.2O.sub.3/Al.sub.2O.sub.3, CoCl.sub.2/AlF.sub.3,
NiCl.sub.2/AlF.sub.3 and combinations thereof.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a process to prepare
2-chloro-3,3,3-trifluoropropene (HCO-1233xf) or
2-chloro-1,1,12-tetrafluoropropane (HCFC-244bb) using
dichloro-trifluoropropanes and/or trichloro-difluoropropanes, and
to prepare 2-chloro-3,3,3-trifluoropropene (HCO-1233xf) using
various 242 and 243 isomers.
BACKGROUND OF THE INVENTION
[0002] Certain hydrofluoroolefins (HFOs), such as
tetrafluoropropenes (including 2,3,3,3-tetrafluoropropene
(HFO-1234yf), are now known to be effective refrigerants, heat
transfer media, propellants, foaming agents, blowing agents,
gaseous dielectrics, sterilant carriers, polymerization media,
particulate removal fluids, carrier fluids, buffing abrasive
agents, displacement drying agents and power cycle working fluids.
Unlike most chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons
(HCFCs), most HFOs pose no threat to the ozone layer. HFO-1234yf
has also been shown to be a low global warming compound with low
toxicity and, hence, can meet increasingly stringent requirements
for refrigerants in mobile air conditioning. Accordingly,
compositions containing HFO-1234yf is a leader among the materials
being developed for use in many of the aforementioned
applications.
[0003] Several methods of preparing HFOs are known. For example,
U.S. Pat. No. 4,900,874 (Ihara et al) describes a method of making
fluorine containing olefins by contacting hydrogen gas with
fluorinated alcohols. Although this appears to be a relatively
high-yield process, commercial scale handling of hydrogen gas at
high temperature is potentially hazardous. Also, the cost of
commercially producing hydrogen gas, such as building an on-site
hydrogen plant, is economically costly.
[0004] U.S. Pat. No. 2,931,840 (Marquis) describes a method of
making fluorine containing olefins by pyrolysis of methyl chloride
and tetrafluoroethylene or chlorodifluoromethane. This process is a
relatively low yield process and a very large percentage of the
organic starting material is converted to unwanted and/or
unimportant byproducts, including a sizeable amount of carbon black
which tends to deactivate the catalyst used in the process.
[0005] The preparation of HFO-1234yf from trifluoroacetylacetone
and sulfur tetrafluoride has been described (See Banks, et al.,
Journal of Fluorine Chemistry, Vol. 82, Iss. 2, p. 171-174 (1997)).
Also, U.S. Pat. No. 5,162,594 (Krespan) discloses a process wherein
tetrafluoroethylene is reacted with another fluorinated ethylene in
the liquid phase to produce a polyfluoroolefin product.
[0006] Notwithstanding the above-noted process and other processes
for producing fluorinated olefins in general and fluorinated
propenes in particular, applicants have come to appreciate that a
need remains for a more economically efficient means of producing
hydrofluoroolefins in general and hydrofluoropropenes in
particular, such as HFO-1234yf. The present invention satisfies
this need among others.
SUMMARY OF THE INVENTION
[0007] It has been found that certain dichlorotrifluoropropane and
trichlorodifluoropropane by-products produced in the manufacture of
2-chloro-3,3,3-trifluoropropene (HFO-1233xf) and
2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) can be further
converted to the desired HFO-1233xf and/or HCFC-244bb product. Such
dichlorotrifluoropropanes include, but are not limited to,
2,2-dichloro-1,1,1-trifluoropropane (HCFC-243ab),
2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db),
1,2-dichloro-1,1,2-trifluoropropane (HCFC-243bc), and combinations
thereof. Trichlorodifluoropropanes include, but are not limited to,
1,2,2-trichloro-1,1-difluoropropane (HCFC-242ac),
1,1,2-trichloro-1,2-difluoropropane (HCFC-242bc),
1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc), and combinations
thereof.
[0008] In one aspect, the present invention relates to a process
for preparing 2-chloro-3,3,3,-trifluoropropene or
2-chloro-1,1,1,2-tetrafluoropropane that includes at least the
following steps: [0009] a. providing a feed stream comprising one
or more dichlorotrifluoropropanes, such as 2,2-dichloro-
1,1,1-trifluoropropane (HCFC-243ab),
2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db),
1,2-dichloro-1,1,2-trifluoropropane (HCFC-243bc), and combinations
thereof; and/or one or more trichlorodifluoropropanes such as
1,2,2-trichloro-1,1-difluoropropane (HCFC-242ac),
1,1,2-trichloro-1,2-difluoropropane (HCFC-242bc),
1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc), and combinations
thereof, [0010] b. contacting the feed stream with anhydrous
hydrogen fluoride in gas phase in the presence of a fluorination
catalyst under conditions sufficient to produce a product stream
comprising 2-chloro-3,3,3,-trifluoropropene and/or
2-chloro-1,1,1,2-tetrafluoropropane, and HCl, and [0011] c.
isolating 2-chloro-3,3,3,-trifluoropropene and/or
2-chloro-1,1,1,2-tetrafluoropropane from the said product
stream.
[0012] In another aspect, the present invention relates to a
process for preparing 2-chloro-3,3,3-trifluoropropene by providing
a starting composition including at least one compound of formula
I, II, and/or III
CX.sub.2.dbd.CCl--CH.sub.2X (I)
CX.sub.3--CCl.dbd.CH.sub.2 (II)
CX.sub.3--CHCl--CH.sub.2X (III)
wherein X is independently selected from F, Cl, Br, and I, provided
that at least one X is not fluorine. Such starting composition is
contacted with a fluorinating agent to produce a final composition
including 2-chloro-3,3,3-trifluoropropene (1233xf), HCl, unreacted
HF, optional unreacted starting compound(s), and one or more
by-products. The by-products may include one or a combination of
trichlorofluoropropene (1231) isomers,
2,3-dichloro-3,3-difluoropropene (1232xf),
2-chloro-1,1,1,2-tetrafluoropropane (244bb),
1,1,1,2,2-pentafluoropropane (245cb), dichlorotrifluoropropanes
(243), trichlorodifluoropropanes (242). The
dichlorotrifluoropropanes and trichlorodifluoropropanes may
include, but are not limited to, one or a combination of those
compounds identified above or otherwise herein.
[0013] This final composition is then processed to separate desired
products and recyclables from the remainder of the composition. In
one aspect, 1233xf and HCl are first separated by feeding the
composition into a recycle or distillation column From such a
column, the lighter components, such as 1233xf, 244bb (if any),
245cb (if any), HCl, and a portion of unreacted HF are isolated in
a first or top stream, and the remaining organic components, such
as unreacted HF, optional unreacted started compounds, one or more
by-products (e.g. 242 and 243 isomers), and residual 1233xf are
recovered in a second or bottom stream. From the top stream, 1233xf
is purified using standard distillation methods, such as those
provided herein. It is then forwarded to the second step of the
reaction (discussed below) to produce 244bb and, ultimately,
1234yf.
[0014] The bottom stream of the recycle or distillation column is
then further processed to isolate recyclable compounds from the
first reaction step. Unreacted HF, for example, is substantially
separated by phase separation. More specifically, the second or
bottom stream from the recycle column is provided to a phase
separator where unreacted HF separates into a first layer. In
certain embodiments, this first layer also includes, as a residual
portion, certain of the organics such as, but not limited to,
1233xf, 1232xf, and 243. The remaining organics (e.g. optional
unreacted starting compound, residual 1233xf, and one or more
by-products, which may include 1232xf, 242, and/or 243) are
separated into a second layer. The HF-rich first layer is then
extracted, optionally purified, and recycled. The second layer is
similarly extracted and the unreacted starting material (if any)
and recyclable products and/or by-products purified for recycling.
In certain embodiments of the invention, the purified by-products
preferably include at least one or more of the 242 and/or 243
isomers provided herein which are recycled to the first step
fluorination reaction to produce 1233xf and/or 244bb.
[0015] In an alternative embodiment of the foregoing, the final
composition of the reaction includes each of at least
2-chloro-3,3,3-trifluoropropene (1233xf), HCl, unreacted HF,
optional unreacted starting compound, trichlorofluoropropene (1231)
isomers, 2,3-dichloro-3,3-difluoropropene (1232xf), a first
by-product selected from the group consisting of
1,1,1,2-tetrafluoropropane (244bb), 1,1,1,2,2-pentafluoropropane
(245cb), and combinations thereof, and a second by-product selected
from the group consisting of dichlorotrifluoropropane (243),
trichlorodifluoropropane (242), and combinations thereof.
[0016] The final composition is then fed into a recycle or
distillation column, where the lighter components, such as 1233xf,
first by-product(s), HCl, and a portion of unreacted HF are
isolated from the column in a first or top stream. The remaining
components, such as unreacted HF, optional unreacted started
compounds, residual 1233xf, trichlorofluoropropene (1231) isomers,
2,3-dichloro-3,3-difluoropropene (1232xf), second by-product(s) and
third by-product(s) are recovered in a second or bottom stream.
[0017] From the top stream, the 1233xf is purified using standard
methods, such as those described herein, and forwarded to the
second stage of the reaction to produce 244bb.
[0018] The compounds in the bottom stream may then be further
separated to isolate recyclable compounds from the first reaction
step. Unreacted HF, for example, is separated by phase separation.
More specifically, the second stream from the recycle column is
provided to a phase separator where the majority of unreacted HF
separates into a first layer. In certain embodiments, this first
layer also includes, as a residual portion, certain of the organics
such as, but not limited to, 1233xf, 1232xf, and 243. The remaining
organics not provided in the first layer (e.g. optional unreacted
starting compound, residual amounts of 1233xf, 1231 isomers,
1232xf, and second and third by-product(s)), and a small portion of
unreacted HF) are separated into a second layer. The first layer,
which is rich in HF, is then extracted, optionally purified, and
recycled. With the second layer, the optional unreacted starting
compound, trichlorofluoropropene (1231) isomers,
2,3-dichloro-3,3-difluoropropene (1232xf), second by-product(s)
(e.g. 242 and/or 243) are separated from the third by-products by a
high boiler purge system and are recycled. The optional unreacted
starting compound, trichlorofluoropropene (1231) isomers,
2,3-dichloro-3,3-difluoropropene (1232xf), residual amounts of
1233xf and second by-product(s) may then be recycled to the reactor
alone or in conjunction with the second by-products (e.g. 242
and/or 243).
[0019] It has been found that the separation of the components in
the bottom stream of the first recycle column (e.g. HF, unreacted
starting compound, and certain by-products, such as 242 and 243
isomers) allows for easier recycle of reactants back into reactor.
The economy of the process is also improved by purifying such
recycles and removing undesirable by-products that deleteriously
affect catalyst life or otherwise degrade the reactor. To this end,
the processes of the present invention result in reduced catalyst
deactivation, as a result of the recycles, and corrosion of the
reactor is minimized The process to the present invention also
result in higher reaction efficiency and reduction of waste by
recycling unreacted and/or underfluorinated compounds, which are
further converted into the desired products. To this end the
present invention is further advantageous because it provides one
or more process steps for improving the reaction efficiency used
for the production of HFOs, such as
2-chloro-3,3,3,-trifluoropropene (1233xf) or, more broadly, for the
production of 2,3,3,3-tetrafluoropropene (1234yf), of which 1233xf
is a known intermediate. Additional embodiments and advantages to
the present invention will be readily apparent to one of skill in
the art, based on the disclosure provided herein.
[0020] In another aspect, it has found that in reacting 1233xf with
HF to form 244bb, varying amounts of 243ab are formed as
by-product. This is often particularly the case when a chloride
such as HCl is a co-feed to this reaction. The unwanted generation
of 243ab comes at the expense of 244bb yield. In another embodiment
of the invention, 243ab formed in this regard, is converted to
1233xf which can be returned to the reaction to form 244bb. In one
practice, the conversion of 243ab to 1233xf is by
dehydrochlorination using select catalysts, such as carbon solids,
metal halides, halogenated metal oxides, zero metals, and the like.
In a preferred embodiment, the 243ab is dehydrochlorinated in the
reaction whereby 244bb is converted to 1234yf. The 243ab is
concurrently converted to 1233xf which can then be re-used as
above.
[0021] In one embodiment, the invention is to a process to prepare
2-chloro-3,3,3-trifluoropropene (HCO-1233xf) or
2-chloro-1,1,12-tetrafluoropropane (HCFC-244bb) comprising
contacting a compound selected from the group consisting of a
dichloro-trifluoropropane, a trichloro-difluoropropane, and
combinations thereof, with anhydrous hydrogen fluoride (HF) under
conditions effective to produce 2-chloro-3,3,3-trifluoropropene
(HCO-1233xf), 2-chloro-1,1,12-tetrafluoropropane (HCFC-244bb), or
combinations thereof. In one embodiment, the process is practiced
with the proviso that 2,3-dichloro-1,1,1-trifluoropropane
(HCFC-243db) is excluded from the dichloro-trifluoropropanes when
preparing HCO-1233xf. In another embodiment, the invention is
directed to process to prepare 2-chloro-1,1,12-tetrafluoropropane
(HCFC-244bb) comprising contacting a compound selected from the
group consisting of a dichloro-trifluoropropane, a
trichloro-difluoropropane, and combinations thereof, with anhydrous
hydrogen fluoride (HF) under conditions effective to produce
HCFC-244bb.
[0022] In another embodiment, the invention is to a process to
prepare 2-chloro-3,3,3-trifluoropropene (HCO-1233xf) and
2-chloro-1,1,1,2-tetrafluoropropane (244bb) comprising a contacting
step comprising contacting at least one compound of Formulae (I),
(II), (III)
CX.sub.2.dbd.CCl--CH.sub.2X (I)
CX.sub.3--CCl.dbd.CH.sub.2 (II)
CX.sub.3--CHCl--CH.sub.2X (III)
[0023] wherein X is independently selected from F, Cl, Br, and I,
provided that at least one X is not fluorine, with anhydrous
hydrogen fluoride (HF) in the presence of a catalyst under
conditions effective to form a composition comprising HCO-1233xf
and a by-product selected from the group consisting of a
dichloro-trifluoropropane, a trichloro-difluoropropane and
combinations thereof; recovering the by-product from the
composition; recycling the by-product to the contacting step
wherein the by-product is converted to
2-chloro-1,1,1,2-tetrafluoropropane (244bb).
[0024] In another embodiment, the invention is to a process to
prepare 2-chloro-3,3,3-trifluoropropene (HCO-1233xf) comprising
contacting 1,1,1-trifluoro-2,2-dichloropropane (243ab) with a
dehydrochlorination catalyst under conditions effective to form
1233xf.
DETAILED DESCRIPTION OF THE INVENTION
[0025] According to one embodiment, the present invention relates
to a manufacturing process for making 2,3,3,3-tetrafluoroprop-1-ene
using a starting material according to any one or combination of
formulas I, II, and/or III:
CX.sub.2.dbd.CCl--CH.sub.2X (Formula I)
CX.sub.3--CCl.dbd.CH.sub.2 (Formula II)
CX.sub.3--CHCl--CH.sub.2X (Formula III)
wherein X is independently selected from F, Cl, Br, and I, provided
that at least one X is not fluorine. In certain embodiments, the
compound(s) of Formula I, II and/or III contains at least one
chlorine, a majority of the Xs as chlorine, or all Xs as chlorine.
In certain embodiments, the compound(s) of formula I includes
1,1,2,3-tetrachloropropene (1230xa). In certain embodiments, the
compound(s) of formula II includes 2,3,3,3-tetrachloropropene
(1230xf). In further embodiments, the compound(s) of formula III
include 1,1,1,2,3-pentachloropropane (240db).
[0026] The method generally includes at least three reaction steps.
In the first step, a starting composition including compounds of
Formula I, II, and/or III (e.g. 1,1,2,3-tetrachloropropene,
2,3,3,3-tetrachloropropene, and/or 1,1,1,2,3-pentachloropropane) is
reacted with anhydrous HF in a first vapor phase reactor
(fluorination reactor) to produce a mixture of
2-chloro-3,3,3-trifluoropropene (1233xf) and HCl. In certain
embodiments, the reaction occurs in the vapor phase in the presence
of a vapor phase catalyst, such as, but not limited to, a
fluorinated chromium oxide. The catalyst may (or may not) have to
be activated with anhydrous hydrogen fluoride HF (hydrogen fluoride
gas) before use depending on the state of the catalyst.
[0027] While fluorinated chromium oxides are disclosed as the vapor
phase catalyst, the present invention is not limited to this
embodiment. Any fluorination catalysts known in the art may be used
in this process. Suitable catalysts include, but are not limited to
chromium, aluminum, cobalt, manganese, nickel and iron oxides,
hydroxides, halides, oxyhalides, inorganic salts thereof and their
mixtures and any one of which may be optionally fluorinated.
Combinations of catalysts suitable for the present invention
nonexclusively include Cr.sub.2O.sub.3, FeCl.sub.3/C,
Cr.sub.2O.sub.3/Al.sub.2O.sub.3, Cr.sub.2O.sub.3/AlF.sub.3,
Cr.sub.2O.sub.3/carbon, CoCl.sub.2/Cr.sub.2O.sub.3/Al.sub.2O.sub.3,
NiCl.sub.2/Cr.sub.2O.sub.3/Al.sub.2O.sub.3, CoCl.sub.2/AlF.sub.3,
NiCl.sub.2/AlF.sub.3 and mixtures thereof. Chromium oxide/aluminum
oxide catalysts are described in U.S. Pat. No. 5,155,082 which is
incorporated herein by reference. Chromium (III) oxides such as
crystalline chromium oxide or amorphous chromium oxide are
preferred with amorphous chromium oxide being most preferred.
Chromium oxide (Cr.sub.2O.sub.3) is a commercially available
material which may be purchased in a variety of particle sizes.
Fluorination catalysts having a purity of at least 98% are
preferred. The fluorination catalyst is present in an excess but in
at least an amount sufficient to drive the reaction.
[0028] This first step of the reaction may be conducted in any
reactor suitable for a vapor phase fluorination reaction. In
certain embodiments, the reactor is constructed from materials
which are resistant to the corrosive effects of hydrogen fluoride
and catalyst such as Hastalloy, Nickel, Incoloy, Inconel, Monel and
fluoropolymer linings. If desired, inert gases such as nitrogen or
argon may be employed in the reactor during operation.
[0029] When the compound of formula I is 1230xa, the mol ratio of
HF to 1230xa in step 1 of the reaction is 1:1 to 50:1, from about
10:1 to about 50:1, or from about 10:1 to about 20:1. The reaction
between HF and 1230xa is carried out at a temperature from about
150.degree. C. to about 500.degree. C., in certain embodiments,
about 150.degree. C. to about 400.degree. C., or about 150.degree.
C. to about 300.degree. C. The reaction pressure is about of about
0 psig to about 500 psig, in certain embodiments from about 20 psig
to about 200 psig, or about 50 to about 100 psig.
[0030] Similarly, when the compound of formula II is 1230xf, the
mol ratio of HF to 1230xf in step 1 of the reaction is 1:1 to 50:1,
from about 10:1 to about 50:1, or from about 10:1 to about 20:1.
The reaction between HF and 1230xf is carried out at a temperature
from about 150.degree. C. to about 500.degree. C., in certain
embodiments, about 150.degree. C. to about 400.degree. C., or about
150.degree. C. to about 300.degree. C. The reaction pressure is
about of about 0 psig to about 500 psig, in certain embodiments
from about 20 psig to about 200 psig, or about 50 to about 100
psig.
[0031] Similarly, when the compound of formula III is 240db, the
mol ratio of HF to 240db in step 1 of the reaction is 1:1 to 50:1,
from about 10:1 to about 50:1, or from about 10:1 to about 20:1.
The reaction between HF and 240db is carried out at a temperature
from about 150.degree. C. to about 500.degree. C., in certain
embodiments, about 150.degree. C. to about 400.degree. C., or about
150.degree. C. to about 300.degree. C. The reaction pressure is
about of about 0 psig to about 500 psig, in certain embodiments
from about 20 psig to about 200 psig, or about 50 to about 100
psig.
[0032] The fluorination reaction may be carried out to attain a
single- or multi-pass conversion of at least 1% or higher, 5% or
higher, 10% or higher or about 20% or higher. In certain preferred
embodiments of the present invention, the starting reagent is
converted to 1233xf in a single pass, wherein the reaction
conditions achieve a conversion amount greater than 75%, greater
than 85%, greater than 95% or greater than 99%. To this end, the
resulting effluent includes small or trace amounts of unreacted
starting material or may be substantially free of such
compounds.
[0033] The effluent from the fluorination reaction step, including
any intermediate effluents that may be present in multi-stage
reactor arrangements, are processed to achieve desired degrees of
separation and/or other processing. For example, in embodiments in
which the reactor effluent includes 1233xf, the effluent will
generally also include HCl, unreacted HF, and trace amounts, if
any, of unreacted starting component (e.g. 1230xa, 1230xf and/or
240db). The effluent may also include one or more by-product
organics such as underfluorinated and/or overfluorinated
intermediates. Non-limiting examples of underfluorinated
intermediates include trichlorofluoropropene (1231) isomers and
2,3-dichloro-3,3-difluoropropene (1232xf), and non-limiting
examples of overfluorinated intermediates include
2-chloro-1,1,1,2-tetrafluoropropane (244bb) and
1,1,1,2,2-pentafluoropropane (245cb). Other by-product organics may
also include, but are not limited to, dichlorotrifluoropropane
(243), and trichlorodifluoropropane (242).
[0034] In certain embodiments, the reaction by-products include one
or more of dichlorotrifluoropropane and/or
trichlorodifluororpropane by-products. Such
dichlorotrifluoropropanes include, but are not limited to, one or
more of the compounds 2,2-dichloro-1,1,1-trifluoropropane
(HCFC-243ab), 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db), and
1,2-dichloro-1,1,2-trifluoropropane (HCFC-243bc).
Trichlorodifluoropropanes include, but are not limited to, one or
more of the compounds 1,2,2-trichloro-1,1-difluoropropane
(HCFC-242ac), 1,1,2-trichloro-1,2-difluoropropane (HCFC-242bc), and
1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc).
[0035] The effluent may be processed in one or more steps to
isolate the 1233xf, as well as certain unreacted components and/or
byproducts that are useful as a recyclables (including, but not
limited to, the 242 and 243 isomers). Such isolation steps include
those known in the art, and include without limitation, those
described in U.S. Pat. Nos. 8,258,355 and 8,084,653 the entire
contents of which are incorporated herein by reference. In one
embodiment, a first recycle column, such as a distillation column
is provided. The lighter components of the effluent are isolated
from the top of the first recycle column and cooled and include one
or more of HCl, 1233xf, 244bb (if any), 245cb (if any) and a
portion of unreacted HF. The remaining compounds are collected at
the bottom stream of the column and include a bulk of the unreacted
HF, trace amounts of unreacted starting component (if any),
residual 1233xf and one or more of the by-product organics
discussed herein. When referring to the bottom stream of the
column, a "residual" amount of 1233xf refers to less than about 30
wt %, less than about 20%, less than about 15%, or less than about
10% of the total weight of the components in the bottom stream.
[0036] Each of the top stream and bottom stream are then
independently processed. The top stream, for example, is first fed
into an HCl column for HCl removal. High purity HCl is isolated
from the top of the column and fed to an HCl recovery system. By
way of non-limiting example, in such a recovery system HCl from the
top stream may be absorbed in de-ionized water as concentrated HCl
which, optionally, can be recovered for later sale. The remaining
components, including 1233xf, 244bb (if any), 245cb (if any), and
HF, exit the bottom of the HCl column and are further processed. In
certain embodiments, this bottom stream is then provided to an HF
recovery system to recover HF. The 1233xf/HF stream is fed to a
sulfuric acid extractor or a phase separator for removal of HF from
this mixture, i.e. the HF is either dissolved in sulfuric acid or
phase separated from the organic mixture. With the former, HF is
desorbed from the sulfuric acid/HF mixture by heating and
distillation and recycled back to the reactor. In the case where a
phase separator is used, HF is phase-separated using standard
methods, such as those discussed below, and recycled back to the
reactor. The organic either from the overhead of the sulfuric acid
extractor or from the bottom layer of the phase separator is fed to
the hydrofluorination reactor of Step (2), discussed below.
[0037] Components within the bottom stream of the first recycle
column are separated, in certain embodiments, by phase separation.
More specifically, the mixture is provided to a cooler and then to
a phase separator where unreacted HF separates into an HF-rich
first or top layer and an organic rich bottom or second layer. Any
pressure which maintains the mixture substantially in the liquid
phase may be employed. To this end, the pressure and temperature of
the mixture may be adjusted such that the mixture remains
substantially in the liquid phase. In certain embodiments, the
HF-rich layer also includes, as a residual portion, certain of the
organics such as, but not limited to 1233xf, 1232xf and 243. The
remaining organics not provided in the first layer (particularly
unreacted starting compound(s) (if any), residual 1233xf, 242
isomers, 243 isomers and dimers) separate into the organic-rich
second or bottom layer. (When referring to the top layer, a
"residual portion" of organics refers to less than about 50 wt %,
less than about 40%, less than about 30%, less than about 20%, or
less than about 10% of the total weight of the components in the
top layer.) Phase separation may be performed at any combination of
temperature and pressure such that two distinct liquid phases are
formed in the phase separator. Phase separation may be carried out
between about -30.degree. C. to 60.degree. C., preferably between
about 0.degree. C. and 40 .degree. C. and more preferably between
about 10.degree. C. and 30.degree. C.
[0038] The HF rich layer is then isolated, such as by an HF phase
pump, optionally purified, and recycled back to the reactor via a
vaporizer. In one embodiment, the HF-rich layer is distilled to
remove any moisture buildup or is isolated by single stage flash
distillation. In another embodiment, before the recycle of HF-rich
stream moisture (if any) is removed by injecting a chemical reagent
such as COCl.sub.2 (or SOCl.sub.2) into said stream, which reacts
with moisture to form CO.sub.2 (or SO.sub.2) and HCl. In even
further embodiments, the HF-rich layer may be purified to remove
the residual organics or may be recycled with the organics.
[0039] The organic-rich layer is also isolated, such as by an
organic phase pump, then further processed to separate and purify
the unreacted starting reactants (if any) and recyclable
intermediates or by-products. In certain embodiments, the
organic-rich layer is provided to a high boiler purge system, where
unreacted starting reagents (if any), residual 1233xf, 1231
isomers, 1232xf, 243 isomers, 242 isomers, etc. are recovered and
undesirable by-products are removed. (When referring to the
organic-rich layer, a "residual" amount of HF refers to less than
about 15 wt %, less than about 10%, less than about 5%, or less
that about 3% of the total weight of the components in the bottom
layer.) The high boiler purge system may be a distillation system
operated in batch or continuous mode, preferably batch for
operational reasons. Another option is to use a flash or series of
flashes. In either case (distillation or flash), the more volatile
components are recovered and recycled while the heavier components
are removed from the system.
[0040] It has been found that the separation of the components in
the bottom stream of the first recycle column into two phases
allows for easier recycle of reactants back into reactor, and that
the economy of the process is improved by using phase separator
followed by purification of one or both layers before recycling. A
presence of moisture in the feed, for example, leads to catalyst
deactivation and corrosion of equipment and piping. Such moisture,
if present, will typically concentrate in the HF-rich layer during
phase separation. Accordingly, by purifying the HF-rich layer
post-isolation, the moisture may be removed and the catalyst
deactivation and corrosion minimized
[0041] Removal of the high boiling point by-products and impurities
is similarly advantageous because such compounds also cause
catalyst deactivation if recycled. During phase separation, as set
forth above, such compounds tend to concentrate in organic layer.
Accordingly, post-isolation, the organic layer can also be purified
in accordance with the foregoing to remove such compounds and
isolate only those compound that are recyclable. Removal of the
high boiling point compounds results in improved catalyst life and
minimal purge streams.
[0042] In the second step of the process for forming
2,3,3,3-tetrafluoroprop-1-ene, the purified 1233xf intermediate
stream is converted to 2-chloro-1,1,1,2-tetrafluoropropane (244bb).
In one embodiment, this step may be performed in the liquid phase
in a liquid phase reactor, which may be TFE or PFA-lined. Such a
process may be performed in a temperature range of about
70-120.degree. C. and about 50-120 psig.
[0043] Any liquid phase fluorination catalyst may be used in the
invention. A non-exhaustive list include Lewis acids, transition
metal halides, transition metal oxides, Group IVb metal halides,
Group Vb metal halides, or combinations thereof. Non-exclusive
examples of liquid phase fluorination catalysts are an antimony
halide, a tin halide, a tantalum halide, a titanium halide, a
niobium halide, and molybdenum halide, an iron halide, a
fluorinated chrome halide, a fluorinated chrome oxide or
combinations thereof. Specific non-exclusive examples of liquid
phase fluorination catalysts are SbCl.sub.5, SbCl.sub.3, SbF.sub.5,
SnCl.sub.4, TaCl.sub.5, TiCl.sub.4, NbCl.sub.5, MoCl.sub.6,
FeCl.sub.3, a fluorinated species of SbCl.sub.5, a fluorinated
species of SbCl.sub.3, a fluorinated species of SnCl.sub.4, a
fluorinated species of TaCl.sub.5, a fluorinated species of
TiCl.sub.4, a fluorinated species of NbCl.sub.5, a fluorinated
species of MoCl.sub.6, a fluorinated species of FeCl.sub.3, or
combinations thereof. Antimony pentachloride is most preferred.
[0044] These catalysts can be readily regenerated by any means
known in the art if they become deactivated. One suitable method of
regenerating the catalyst involves flowing a stream of chlorine
through the catalyst. For example, from about 0.002 to about 0.2 lb
per hour of chlorine can be added to the liquid phase reaction for
every pound of liquid phase fluorination catalyst. This may be
done, for example, for from about 1 to about 2 hours or
continuously at a temperature of from about 65.degree. C. to about
100.degree. C.
[0045] This second step of the reaction is not necessarily limited
to a liquid phase reaction and may also be performed using a vapor
phase reaction or a combination of liquid and vapor phases, such as
that disclosed in U.S. Published Patent Application No.
20070197842, the contents of which are incorporated herein by
reference. To this end, the 1233xf containing feed stream is
preheated to a temperature of from about 50.degree. C. to about
400.degree. C., and is contacted with a catalyst and fluorinating
agent. Catalysts may include standard vapor phase agents used for
such a reaction and fluorinating agents may include those generally
known in the art, such as, but not limited to, hydrogen
fluoride.
[0046] In this second step of the reaction, it is found that 243ab
may be formed in varying degrees as a by-product. This is often
particularly the case when a chloride such as HCl is a co-feed to
this reaction. The unwanted generation of 243ab comes at the
expense of 244bb yield. In one aspect of the invention, the 243ab
thus formed is converted to 1233xf by catalytic
dehydrochlorination. The 1233xf obtained by this conversion can be
recycled back to the second step of the reaction or used for other
purposes. In one embodiment, the 243ab is separately converted to
recyclable 1233xf, subject to removal of 243ab from the product
mixture of the second step of the reaction, as known in the art.
Preferably, the 243ab is sent to the third step of the reaction,
discussed hereunder, whereby it is dehydrochlorinated to form
1233xf as part of the process to dehydrochlorinate 244bb to 1234yf.
Conveniently, the same reactor, catalysts, and conditions may be
employed. The 1233xf thus obtained can be separated to the extent
necessary as known in the art, and can be recycled back to the
second step of the reaction whereby 244bb is generated, or it can
be used otherwise.
[0047] In the third step of 1234yf production, the 244bb is fed to
a second vapor phase reactor (dehydrochlorination reactor) to be
dehydrochlorinated to make the desired product
2,3,3,3-tetrafluoroprop-1-ene (1234yf). This reactor contains a
catalyst that can catalytically dehydrochlorinate HCFC-244bb to
make HFO-1234yf.
[0048] In another aspect of the invention, the 244bb that is fed to
the third step of 1234yf production process further comprises all
or part of the 243ab that may have formed in the second step of the
reaction. The reactor and catalyst suitable for dehydrochlorinating
244bb to 1234yf in this third step can also act to
dehydrochlorinate 243ab to 1233xf, which can be optionally reused
via recycle.
[0049] The catalysts may be metal halides, halogenated metal
oxides, neutral (or zero oxidation state) metal or metal alloy, or
activated carbon in bulk or supported form. Metal halide or metal
oxide catalysts may include, but are not limited to, mono-, bi-,
and tri-valent metal halides, oxides and their
mixtures/combinations, and more preferably mono-, and bi-valent
metal halides and their mixtures/combinations. Component metals
include, but are not limited to, Cr.sup.3+, Fe.sup.3+, Mg.sup.2+,
Ca.sup.2+, Ni.sup.2+, Zn.sup.2+, Pd.sup.2+, Li.sup.+, Na.sup.+,
K.sup.+, and Cs.sup.+. Component halogens include, but are not
limited to, F.sup.-, Cl.sup.-, Br.sup.-, and I.sup.-. Examples of
useful mono- or bi-valent metal halide include, but are not limited
to, LiF, NaF, KF, CsF, MgF.sub.2, CaF.sub.2, LiCl, NaCl, KCl, and
CsCl. Halogenation treatments can include any of those known in the
prior art, particularly those that employ HF, F.sub.2, HCl,
Cl.sub.2, HBr, Br.sub.2, HI, and I.sub.2 as the halogenation
source.
[0050] When neutral, i.e., zero valent, metals, metal alloys and
their mixtures are used. Useful metals include, but are not limited
to, Pd, Pt, Rh, Fe, Co, Ni, Cu, Mo, Cr, Mn, and combinations of the
foregoing as alloys or mixtures. The catalyst may be supported or
unsupported. Useful examples of metal alloys include, but are not
limited to, SS 316, Monel 400, Inconel 825, Inconel 600, and
Inconel 625. Such catalysts may be provided as discrete supported
or unsupported elements and/or as part of the reactor and/or the
reactor walls.
[0051] Preferred, but non-limiting, catalysts include activated
carbon, stainless steel (e.g. SS 316), austenitic nickel-based
alloys (e.g. Inconel 625), nickel, fluorinated 10% CsCl/MgO, and
10% CsCl/MgF.sub.2. The reaction temperature is preferably about
300-550.degree. C. and the reaction pressure may be between about
0-150 psig. The reactor effluent may be fed to a caustic scrubber
or to a distillation column to remove the by-product of HCl to
produce an acid-free organic product which, optionally, may undergo
further purification using one or any combination of purification
techniques that are known in the art.
[0052] The aforementioned catalysts for dehydrochlorination of
244bb to 1234yf are also useful for dehydrochlorination of 243ab to
1233xf, including in practices where this latter
dehydrochlorination occurs in the third step of the reaction, as
preferred, or is separately performed.
* * * * *