U.S. patent application number 13/046958 was filed with the patent office on 2011-07-07 for processes for producing 1,2,3,3,3-pentafluoropropene.
This patent application is currently assigned to E. I. DU PONT DE NEMOURS AND COMPANY. Invention is credited to ALLEN CAPRON SIEVERT.
Application Number | 20110163253 13/046958 |
Document ID | / |
Family ID | 38962792 |
Filed Date | 2011-07-07 |
United States Patent
Application |
20110163253 |
Kind Code |
A1 |
SIEVERT; ALLEN CAPRON |
July 7, 2011 |
PROCESSES FOR PRODUCING 1,2,3,3,3-PENTAFLUOROPROPENE
Abstract
A process for making CHF.dbd.CFCF.sub.3 is disclosed. The
process involves (a) reacting CCl.sub.2FCF.sub.2CF.sub.3 with
H.sub.2 in the presence of a catalytically effective amount of
hydrogenation catalyst to form CH.sub.2FCF.sub.2CF.sub.3; and (b)
dehydrofluorinating CH.sub.2FCF.sub.2CF.sub.3 from (a) to form
CHF.dbd.CFCF.sub.3. Also disclosed are compositions including
CCl.sub.3CF.sub.2CF.sub.3 and HF, wherein the HF is present in an
effective amount to form an azeotropic combination with the
CCl.sub.3CF.sub.2CF.sub.3; and compositions including
CCl.sub.2FCF.sub.2CF.sub.3 and HF, wherein the HF is present in an
effective amount to form an azeotropic combination with the
CCl.sub.2FCF.sub.2CF.sub.3.
Inventors: |
SIEVERT; ALLEN CAPRON;
(Elkton, MD) |
Assignee: |
E. I. DU PONT DE NEMOURS AND
COMPANY
Wilmington
DE
|
Family ID: |
38962792 |
Appl. No.: |
13/046958 |
Filed: |
March 14, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12377776 |
Feb 17, 2009 |
7928271 |
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PCT/US07/19319 |
Sep 5, 2007 |
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13046958 |
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60842708 |
Sep 5, 2006 |
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Current U.S.
Class: |
252/2 ;
252/182.12; 252/364; 252/570; 252/67; 510/415; 570/156 |
Current CPC
Class: |
C07C 17/23 20130101;
C07C 17/25 20130101; C07C 17/23 20130101; C07C 21/18 20130101; C09K
5/045 20130101; C07C 17/25 20130101; C09K 2205/126 20130101; C07C
19/08 20130101; C07C 21/18 20130101 |
Class at
Publication: |
252/2 ; 252/67;
570/156; 252/364; 252/182.12; 252/570; 510/415 |
International
Class: |
C09K 5/00 20060101
C09K005/00; C07C 17/25 20060101 C07C017/25; A62D 1/00 20060101
A62D001/00; C09K 3/00 20060101 C09K003/00; H01B 3/24 20060101
H01B003/24; C11D 3/24 20060101 C11D003/24 |
Claims
1. A composition comprising: (a) CCl.sub.2FCF.sub.2CF.sub.3 and (b)
HF; wherein the HF is present in an effective amount to form an
azeotropic combination with the CCl.sub.2FCF.sub.2CF.sub.3.
2. A process for making CHF.dbd.CFCF.sub.3, comprising: (a)
reacting CCl.sub.2FCF.sub.2CF.sub.3 with H.sub.2 in the presence of
a catalytically effective amount of a hydrogenation catalyst to
form CH.sub.2FCF.sub.2CF.sub.3; and (b) dehydrofluorinating
CH.sub.2FCF.sub.2CF.sub.3 from (a) to form CHF.dbd.CFCF.sub.3.
3. The process of claim 2 wherein an azeotropic composition of
CCl.sub.2FCF.sub.2CF.sub.3 with HF is co-fed along with H.sub.2 to
the step (a) reaction zone.
4. The process of claim 3 wherein additional
CCl.sub.2FCF.sub.2CF.sub.3 is also fed to the reaction zone.
5. The process of claim 2 wherein said CCl.sub.2FCF.sub.2CF.sub.3
is produced by the partial hydrofluorination of
CCl.sub.3CF.sub.2CF.sub.3 with HF, the mole ratio of HF to
CCl.sub.3CF.sub.2CF.sub.3 used for said partial hydrofluorination
being about 1.5 or less.
6. The process of claim 5 wherein HF is present in the effluent
from the partial fluorination and CCl.sub.2FCF.sub.2CF.sub.3 from
the partial fluorination effluent is recovered at least in part as
an azeotropic composition comprising CCl.sub.2FCF.sub.2CF.sub.3 and
HF.
7. The process of claim 5 wherein an azeotropic composition of
CCl.sub.3CF.sub.2CF.sub.3 and HF is recovered from the
hydrofluorination reaction zone and recycled thereto.
8. The process of claim 5 wherein CCl.sub.3CF.sub.2CF.sub.3 from
the partial fluorination effluent is recycled to the partial
fluorination reaction zone.
Description
CROSS REFERENCE(S) TO RELATED APPLICATION(S)
[0001] This application is a Divisional of U.S. pending application
Ser. No. 12/377,776, filed Feb. 17, 2009, which is a US National
filing of PCT application PCT/US2007/019319, filed, May 9, 2007,
which claims the benefit of priority of U.S. Provisional
Application 60/842,708, filed May 9, May 2006.
FIELD OF THE INVENTION
[0002] The present invention relates to a process that involves the
production of halogenated hydrocarbon products comprising
1,2,3,3,3-pentafluoropropene and to related azetropic compositions
comprising hydrogen fluoride.
BACKGROUND OF THE INVENTION
[0003] As a result of the Montreal Protocol phasing out ozone
depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons
(HCFCs), industry has been working for the past few decades to find
replacement refrigerants. The solution for most refrigerant
producers has been the commercialization of hydrofluorocarbon (HFC)
refrigerants. The new hydrofluorocarbon refrigerants, HFC-134a
being the most widely used at this time, have zero ozone depletion
potential and thus are not affected by the current regulatory phase
out as a result of the Montreal Protocol. The production of other
hydrofluorocarbons for use in applications such as solvents,
blowing agents, cleaning agents, aerosol propellants, heat transfer
media, dielectrics, fire extinguishants and power cycle working
fluids has also been the subject of considerable interest.
[0004] There is also considerable interest in developing new
refrigerants with reduced global warming potential for the mobile
air-conditioning market.
[0005] HFC-1225ye, having zero ozone depletion and a low global
warming potential, has been identified as a potential refrigerant.
U.S. Pat. No. 5,396,000 discloses a process for producing
HFC-1225ye by dehydrofluorination of CF.sub.3CFHCF.sub.2H
(HFC-236ea). There is a need for new manufacturing processes for
the production of HFC-1225ye.
SUMMARY OF THE INVENTION
[0006] The present invention provides a process for making
CHF.dbd.CFCF.sub.3 (HFC-1225ye). This process comprises (a)
reacting CFC-216cb with H.sub.2 in the presence of a catalytically
effective amount of hydrogenation catalyst to form
CH.sub.2FCF.sub.2CF.sub.3 (HFC-236cb); and (b) dehydrofluorinating
HFC-236cb from (a) to form HFC-1225ye.
[0007] The present invention also provides a composition comprising
(a) CCl.sub.3CF.sub.2CF.sub.3 and (b) HF; wherein the HF is present
in an effective amount to form an azeotropic combination with the
CCl.sub.3CF.sub.2CF.sub.3.
[0008] The present invention also provides a composition comprising
(a) CCl.sub.2FCF.sub.2CF.sub.3 and (b) HF; wherein the HF is
present in an effective amount to form an azeotropic combination
with the CCl.sub.2FCF.sub.2CF.sub.3.
DETAILED DESCRIPTION
[0009] The present invention provides a process for making
HFC-1225ye by a process comprising (a) reacting CFC-216cb with
H.sub.2 in the presence of a catalytically effective amount of
hydrogenation catalyst to form CH.sub.2FCF.sub.2CF.sub.3
(HFC-236cb); and (b) dehydrofluorinating HFC-236cb from (a) to form
HFC-1225ye. HFC-1225ye may exist as one of two configurational
isomers, E or Z. HFC-1225ye as used herein refers to the isomers,
E-HFC-1225ye (CAS Reg No. [5595-10-8]) or Z-HFC-1225ye (CAS Reg.
No. [5528-43-8]), as well as any combinations or mixtures of such
isomers.
[0010] CFC-216cb can be prepared from a variety of starting
materials. For example, CFC-216cb can be prepared by the reaction
of dichlorodifluoromethane with tetrafluoroethylene in the presence
of aluminum chlorofluoride as disclosed by Sievert, et. al. in U.S.
Pat. No. 5,488,189. CFC-216cb may also be prepared by fluorination
of CFC-215cb (CCl.sub.3C.sub.2F.sub.5). CFC-215cb can be prepared
by the reaction of trichlorofluoromethane with tetrafluoroethylene
in the presence of aluminum chloride as reported by Paleta, et. al.
in Collections of Czechoslovia Chemical Communications, Vol. 36,
pages 1867 to 1875 (1971).
[0011] In step (a) of the process of the invention, CFC-216cb is
reacted with hydrogen in the presence of a hydrogenation catalyst.
Hydrogenation catalysts suitable for use in this invention include
catalysts comprising at least one catalytic metal component
selected from the group consisting of rhenium, iron, ruthenium,
osmium, cobalt, rhodium, iridium, nickel, palladium, and platinum.
Said catalytic metal component is typically supported on a carrier
such as carbon or graphite or a metal oxide, fluorinated metal
oxide, or metal fluoride where the carrier metal is selected from
the group consisting of magnesium, aluminum, titanium, vanadium,
chromium, iron, and lanthanum.
[0012] Of note are carbon-supported catalysts in which the carbon
support has been washed with acid and has an ash content below
about 0.1% by weight. Hydrogenation catalysts supported on low ash
carbon are described in U.S. Pat. No. 5,136,113, the teachings of
which are incorporated herein by reference. Of particular note are
palladium catalysts supported on carbon (see e.g., U.S. Pat. No.
5,523,501, the teachings of which are incorporated herein by
reference).
[0013] The relative amount of hydrogen contacted with CFC-216cb is
typically from about one mole of hydrogen per mole of CFC-216cb to
about 15 moles of H.sub.2 per mole of the CFC-216cb starting
material, preferably from about 2 moles of hydrogen per mole of
CFC-216cb to about 8 moles of H.sub.2 per mole of the CFC-216cb
starting material. Suitable reaction temperatures are typically
from about 100.degree. C. to about 350.degree. C., preferably from
about 125.degree. C. to about 300.degree. C. The contact time is
typically from about 1 to about 450 seconds, preferably from about
10 to about 120 seconds. The reactions are typically conducted at
atmospheric pressure or superatmospheric pressure.
[0014] The reaction of CFC-216cb with hydrogen may be carried out
in the liquid phase in a reaction vessel such as an autoclave. The
reaction may also be carried out in the vapor phase in a reaction
vessel such as a tubular reactor.
[0015] The effluent from the reaction zone typically includes HCl,
unreacted hydrogen, HFC-236cb, and one or more of CFC-216cb and
HCFC-226ca (CHClC.sub.2F.sub.5). In one embodiment of the
invention, the HFC-236cb is isolated by separation processes known
in the art such as distillation. The isolated HFC-236cb is then
used for step (b) of the process. Unreacted CFC-216cb and
intermediate products such as HCFC-226ca may be recycled to step
(a) of the process. In one embodiment of the process of the
invention, the effluent from the reaction zone of step (a) is sent
directly to step (b).
[0016] In step (b) of the process of the invention, the HFC-236cb
produced in step (a) is contacted with a dehydrofluorination
catalyst in a reaction zone for time sufficient to convert at least
a portion of the 236cb to HFC-1225ye. Suitable dehydrofluorination
catalysts include chromium oxide (e.g., Cr.sub.2O.sub.3) and
chromium oxyfluorides obtained by treating Cr.sub.2O.sub.3 with a
fluorinating agent such as HF or CCl.sub.3F. Suitable chromium
oxide may be obtained commercially. The dehydrofluorination
reaction may be conducted in a tubular reactor in the vapor phase
at temperatures of from about 200.degree. C. to about 500.degree.
C. The reaction pressures may be subatmospheric, atmospheric, or
superatmospheric. Contact times on the catalyst are typically in
the range of about one second to 1000 seconds (e.g., about 1 second
to about 120 seconds). Further details of this process are
disclosed in U.S. Patent Application No. 60/830,939 filed Jul. 13,
2006, the teachings of which are incorporated by reference.
[0017] In another embodiment of this invention, the HFC-236cb is
contacted with a base as disclosed in U.S. Patent Application No.
60/842,425 (corresponding to attorney docket no. FL-1267) filed
Sep. 5, 2006 (the teachings of which are incorporated by
reference). U.S. Patent Application No. 60/842,425 is the priority
document for International Patent Application No.
PCT/US2007/______.
[0018] Of note are embodiments where HFC-1225ye is a desired
product, and is recovered from the product mixture. The HFC-1225ye
present in the effluent from the reaction zone may be separated
from the other components of the product mixture and unreacted
starting materials by conventional means (e.g., distillation). When
HF is present in the effluent, this separation can also include
isolation of azeotrope or near azeotrope composition of HFC-1225ye
and HF and further processing to produce HF-free HFC-1225ye by
using procedures similar to that disclosed in U.S. Patent
Publication US 2006/0106263 A1, which is incorporated herein by
reference.
[0019] In accordance with the present invention, the CFC-216cb used
as a reactant may be produced by reacting CFC-215cb with hydrogen
fluoride. It is desirable to avoid production of large amounts of
overfluorination products, such as CFC-217ca
(CF.sub.3CF.sub.2CClF.sub.2) and FC-218 (CF.sub.3CF.sub.2CF.sub.3).
Accordingly, the molar ratio of HF to CFC-215cb used for the
partial hydrofluorination is about 1.5 or less (e.g., from about
0.5:1 to 1:1).
[0020] This partial hydrofluorination may be carried out in batch,
semi-continuous, or continuous modes. In the batch mode, liquid
CFC-215cb and hydrogen fluoride are combined in an autoclave or
other suitable reaction vessel and heated to the desired
temperature. Preferably, the process of the invention is carried
out by feeding HF to a reactor containing liquid CFC-215cb held at
the desired reaction temperature. Alternatively, HF may be fed to a
reactor containing CFC-215cb.
[0021] In another embodiment of this partial hydrofluorination,
both HF and CFC-215cb may be fed concurrently in the desired
stoichiometric ratio (about 1:1) to a reactor containing CFC-215cb,
CFC-216cb, or a mixture of thereof.
[0022] In yet another embodiment, CFC-215cb and HF may be fed
either concurrently or separately in the desired stoichiometric
ratio to a heated tubular reactor. The reactor may be empty or
preferably filled with a suitable packing such as Monel.RTM. nickel
alloy turnings or wool, Hastelloy.RTM. nickel alloy turnings or
wool, or other material which allows efficient mixing of liquid
CFC-215cb with hydrogen fluoride vapor. In one embodiment said
tubular reactor is preferably oriented vertically with CFC-215cb
liquid entering the top of the reactor and pre-heated HF vapor
introduced at the bottom of the reactor. The CFC-215cb feed rate is
determined by the length and diameter of the reactor, the
temperature, and the degree of fluorination desired. Slower feed
rates at a given temperature will increase contact time and tend to
increase the fluorine content of the products.
[0023] Temperatures suitable for reacting CFC-215cb with HF are
typically from about 30.degree. C. to about 150.degree. C. in
liquid phase embodiments and from about 100.degree. C. to about
250.degree. C. in vapor phase embodiments. Higher temperatures
typically result in higher conversions of CFC-215cb, but can result
in reduced selectivity due to overfluorination.
[0024] The pressure of the step in which HF and CFC-215cb are
contacted is not critical and in batch reactions is usually taken
to be the autogenous pressure of the system at the reaction
temperature. The pressure of the system increases as hydrogen
chloride is formed by replacement of chlorine substituents for
fluorine subsituents in the CFC-215cb starting material. In a
continuous process it is possible to set the pressure of the
reactor in such a way that the HCl liberated by the reaction is
vented from the reactor. Of note are embodiments in which both HCl
and the azeotrope of HF and CFC-216cb are vented continuously from
the reactor.
[0025] Of note are embodiments wherein CFC-215cb and/or CFC-216cb
are present in the product mixture, and wherein said CFC-215cb and
CFC-216cb are recovered. When CFC-215cb and CFC-216cb are present
in the effluent from the reaction zone, they may also be separated
from the other components of the product mixture by conventional
means (e.g., distillation). CFC-215cb recovered from the reaction
zone may be advantageously recycled thereto. When HF is present in
the effluent, this separation can also include isolation of the
azeotropes or near azeotropes of CFC-215cb and CFC-216cb and HF and
further processing to produce HF-free CFC-215cb and CFC-216cb by
using procedures similar to those disclosed in U.S. Pat. No.
6,540,933. Of note are embodiments wherein HF is fed to the
reaction zone and CFC-215cb and/or CFC-216cb are present in the
product mixture, and wherein at least a portion of CFC-215cb and/or
CFC-216cb are recovered from the product mixture as azeotropes
comprising HF and CFC-215cb and/or CFC-216cb. The HF/CFC-215cb
azeotrope and near azeotrope compositions in the effluent from the
partial fluorination reaction zone can be advantageously recycled
back to the reaction zone and are useful in processes to produce
CFC-216cb, HFC-236cb, and HFC-1225ye. The CFC-216cb/HF azeotrope
may be recovered and sent to step (a), preferably after removal of
the HF component of the azeotrope or can be used for further
fluorination reactions (e.g., producing CFC-217ca
(CF.sub.3CF.sub.2CClF.sub.2)). Of note are embodiments where the
CFC-216cb/HF azeotrope is co-fed along with hydrogen and preferably
additional CFC-216cb to the reaction zone of step (a).
[0026] A catalyst is not needed for the partial hydrofluorination
of CFC-215cb, but may be added if desired to increase the
conversion of CFC-215cb or the rate of the reaction. Suitable
catalysts which may be used for the partial hydrofluorination when
carried out in the liquid phase include carbon, AlF.sub.3,
BF.sub.3, FeX.sub.3 where X is selected from the group consisting
of Cl and F, FeX.sub.3 supported on carbon, SbCl.sub.3-xF.sub.x
(x=0 to 3), AsF.sub.3, MCl.sub.5-yF.sub.y (M=Sb, Nb, Ta, Mo; x=0 to
5), M'Cl.sub.4-zF.sub.z (M'=Sn, Ti, Zr, Hf; z=0 to 4).
[0027] Suitable catalyst which may be used for the partial
hydrofluorination of CFC-215cb when carried out in the vapor phase
include metals (including elemental metals, metal oxides and/or
other metal salts); alumina; fluorided alumina; aluminum fluoride;
metals on alumina; metals on aluminum fluoride; magnesium fluoride
on aluminum fluoride; metals on fluorided alumina; alumina on
carbon; aluminum fluoride on carbon; fluorided alumina on carbon;
metals on carbon; chromium catalysts (e.g., Cr.sub.2O.sub.3 by
itself or with other metals such as Mg, Zn, Fe, Co, Ni, Cu);
mixtures of metals, aluminum fluoride, and graphite; and
chromium-magnesium optionally on graphite.
[0028] Fluorided alumina and aluminum fluoride can be prepared as
described in U.S. Pat. No. 4,902,838. Metals on aluminum fluoride
and metals on fluorided alumina can be prepared by procedures
described in U.S. Pat. No. 4,766,260. Catalysts comprising chromium
are well known in the art (see e.g., U.S. Pat. No. 5,036,036).
Chromium supported on alumina can be prepared as described in U.S.
Pat. No. 3,541,165. Chromium supported on carbon can be prepared as
described in U.S. Pat. No. 3,632,834. Catalysts comprising chromium
and magnesium may be prepared as described in U.S. Pat. No.
6,288,293. Other metals and magnesium optionally on graphite can be
prepared in a similar manner to the latter patent.
[0029] The partial fluorination of CFC-215cb to CFC-216cb may also
be carried out in the absence of HF using fluorination agents known
in the art such as antimony trifluoride, SbF.sub.5-aX.sub.a (where
X=Cl or Br and a=1-4), mixtures formed by the reaction of antimony
trifluoride with chlorine or bromine, or antimony pentafluoride.
Such fluorinations are discussed by Hudlicky in Chemistry of
Organic Fluorine Compounds, published by The MacMillan Company (New
York), 1962, pages 93 to 98.
[0030] The present invention also provides azeotrope or near
azeotrope compositions comprising an effective amount of hydrogen
fluoride combined with a compound selected from CFC-215cb and
CFC-216cb.
[0031] In connection with developing processes for the separation
of the individual compounds from the reaction zone effluent from
the reaction of CFC-215cb with hydrogen fluoride, it is noted that
CFC-215cb and CFC-216cb (as well as HFC-1225ye and HFC-236cb) each
can be present as their respective azeotrope or near azeotrope with
HF. HF may be present as unreacted starting material from the
partial fluorination of CFC-215cb or from the dehydrofluorination
reactions of HFC-236cb (or intermediates containing six fluorines
to compounds containing at least one less fluorine), from
hydrodefluorination side reactions, or from HF co-fed along with
hydrogen to the reaction zone of step (a).
[0032] By effective amount is meant an amount, which, when combined
with CFC-216cbb or CFC-215cb, results in the formation of their
respective azeotrope or near azeotrope mixture. As recognized in
the art, an azeotrope or a near azeotrope composition is an
admixture of two or more different components which, when in liquid
form under a given pressure, will boil at a substantially constant
temperature, which temperature may be higher or lower than the
boiling temperatures of the individual components, and which will
provide a vapor composition essentially identical to the liquid
composition undergoing boiling.
[0033] For the purpose of this discussion, near azeotrope
composition (also commonly referred to as an "azeotrope-like
composition") means a composition that behaves like an azeotrope
(i.e., has constant boiling characteristics or a tendency not to
fractionate upon boiling or evaporation). Thus, the composition of
the vapor formed during boiling or evaporation is the same as or
substantially the same as the original liquid composition. Hence,
during boiling or evaporation, the liquid composition, if it
changes at all, changes only to a minimal or negligible extent.
This is to be contrasted with non-near azeotrope compositions in
which during boiling or evaporation, the liquid composition changes
to a substantial degree.
[0034] Additionally, near azeotrope compositions exhibit dew point
pressure and bubble point pressure with virtually no pressure
differential. That is to say that the difference in the dew point
pressure and bubble point pressure at a given temperature will be a
small value. In this invention, compositions with a difference in
dew point pressure and bubble point pressure of less than or equal
to 3 percent (based upon the bubble point pressure) are considered
to be near azeotropes.
[0035] Accordingly, the essential features of an azeotrope or a
near azeotrope composition are that at a given pressure, the
boiling point of the liquid composition is fixed and that the
composition of the vapor above the boiling composition is
essentially that of the boiling liquid composition (i.e., no
fractionation of the components of the liquid composition takes
place). It is also recognized in the art that both the boiling
point and the weight percentages of each component of the azeotrope
composition may change when the azeotrope or near azeotrope liquid
composition is subjected to boiling at different pressures. Thus,
an azeotrope or a near azeotrope composition may be defined in
terms of the unique relationship that exists among the components
or in terms of the compositional ranges of the components or in
terms of exact weight percentages of each component of the
composition characterized by a fixed boiling point at a specified
pressure. It is also recognized in the art that various azeotrope
compositions (including their boiling points at particular
pressures) may be calculated (see, e.g., W. Schotte Ind. Eng. Chem.
Process Des. Dev. (1980) 19, 432-439). Experimental identification
of azeotrope compositions involving the same components may be used
to confirm the accuracy of such calculations and/or to modify the
calculations at the same or other temperatures and pressures.
[0036] In accordance with this invention, compositions are provided
which comprise CFC-215cb and HF wherein HF is present in an
effective amount to form an azeotropic combination with the
CFC-215cb. According to calculations, CFC-215cb and HF form a
heterogeneous azeotrope. A heterogeneous azeotrope differs from a
homogeneous azeotrope in that a heterogeneous azeotrope composition
comprises two distinct liquid phases in equilibrium with a vapor
phase. Either of the two liquid phases may have a composition that
is quite different from the other liquid phase. The overall
composition of the liquid phases may be said to comprise a weighted
average of the separate liquid phase compositions and that overall
composition of the liquid phases will be substantially the same as
the vapor phase composition at the azeotrope point for a given
temperature and pressure. The azeotropic mixture of CFC-215cb and
HF or CFC-216cb and HF may be directed to a phase separation device
such as a decanter for isolation of HF-rich and organic-rich
phases.
[0037] Calculations of the azeotrope for CFC-215cb and HF have
provided overall compositions comprising from about 84.7 mole
percent to about 98.6 mole percent HF and from about 15.3 mole
percent to about 1.4 mole percent CFC-215cb (which form azeotropes
boiling at a temperature of from about -30.degree. C. to about
120.degree. C. and at a pressure of from about 1.8 psi (12.4 kPa)
to about 327 psi (2255 kPa)). Subsequent to these calculations, an
azeotrope of about 95.2 mole percent HF and 4.8 mole percent
CFC-215cb boiling at a temperature of about 34.7.degree. C. at a
pressure of 28.0 psi (193 kPa), and an azeotrope of about 91.4 mole
percent HF and 8.6 mole percent CFC-215cb boiling at a temperature
of about 84.6.degree. C. at a pressure of 126 psi (689 kPa) were
found. Additional calculations in light of these findings, provided
overall compositions comprising from about 89.1 mole percent to
about 98.1 mole percent HF and from about 10.9 mole percent to
about 1.9 mole percent CFC-215cb (which form azeotropes boiling at
a temperature of from about -20.degree. C. to about 110.degree. C.
and at a pressure of from about 3.0 psi (20.7 kPa) to about 240 psi
(1655 kPa)). In accordance with this invention, compositions are
provided which comprise CFC-216cb and HF wherein HF is present in
an effective amount to form an azeotropic combination with the
CFC-216cb. According to calculations, CFC-216cb and HF also form a
heterogeneous azeotrope. Calculations of the azetrope for CFC-216cb
and HF have provided overall compositions comprising from about
73.1 mole percent to about 90.4 mole percent HF and from about 26.9
mole percent to about 9.6 mole percent CFC-216cb (which form
azeotropes boiling at a temperature of from about -30.degree. C. to
about 120.degree. C. and at a pressure of from about 2.4 psi (16.5
kPa) to about 420 psi (2896 kPa)).
[0038] The reactor, distillation columns, and their associated feed
lines, effluent lines, and associated units used in applying the
processes of this invention should be constructed of materials
resistant to hydrogen fluoride and hydrogen chloride. Typical
materials of construction, well-known to the fluorination art,
include stainless steels, in particular of the austenitic type, the
well-known high nickel alloys, such as Monel.TM. nickel-copper
alloys, Hastelloy.TM. nickel-based alloys and, Inconel.TM.
nickel-chromium alloys, and copper-clad steel.
[0039] The following specific Examples are to be construed as
merely illustrative, and do not constrain the remainder of the
disclosure in any way whatsoever.
EXAMPLES
TABLE-US-00001 [0040] Legend: CFC-216cb CCl.sub.2FC.sub.2F.sub.5
HCFC-226ca CHClFC.sub.2F.sub.5 HFC-236cb CH.sub.2FC.sub.2F.sub.5
HFC-236ea CHF.sub.2CHFCF.sub.3 Z--HFC-1225ye Z--CHF.dbd.CFCF.sub.3
E-HFC-1225ye E-CHF.dbd.CFCF.sub.3
Example 1
Hydrodechlorination of CFC-216cb
[0041] Hydrodechlorination of CFC-216cb is illustrated by the
following prophetic example based largely on the teachings of U.S.
Pat. No. 5,523,501, incorporated herein by reference. CFC-216cb may
be converted to HFC-236cb by reaction of hydrogen over a palladium
catalyst.
[0042] A 2 weight percent palladium supported on acid-washed carbon
catalyst (46 g, 4-8 mesh (4.7-2.4 mm)) is placed in a 33
cm.times.2.54 cm o.d. Hastelloy.RTM. tube. The tube is connected to
a reactor system and surrounded with an electrically-heated
furnace. The catalyst is activated by drying at 150.degree. C. for
several hours under a nitrogen purge (100 sccm, 1.7.times.10.sup.-6
m.sup.3/s) followed by treatment with 1:1 nitrogen:hydrogen (100
sccm, 1.7.times.10.sup.-6 m.sup.3/s each) for 5 hours at
150.degree. C. Finally, the catalyst is treated with hydrogen gas
(100 sccm, 1.7.times.10.sup.-6 m.sup.3/s) at 275.degree. C. for an
additional two hours. The flow of hydrogen is then replaced with
nitrogen (100 sccm, 1.7.times.10.sup.-6 m.sup.3/s) as the
temperature is reduced to 150.degree. C. A mixture of CFC-216cb (52
sccm, 8.8.times.10.sup.-7 m.sup.3/s) and hydrogen (300 sccm,
5.1.times.10.sup.-6 m.sup.3/s) is passed through the catalyst bed
at 150.degree. C. Under these conditions the conversion of
CFC-216cb is essentially complete and the reactor effluent is a
mixture of approximately 3:1 HFC-236cb:HCFC-226ca.
Example 2
Dehydrofluorination of HFC-236cb
[0043] Dehydrofluoination of HFC-236cb is illustrated by the
following prophetic example based largely on the teachings of U.S.
Patent Application No. 60/830,939, filed Jul. 13, 2006 and
International Application No. PCT/US2007/015751, filed Jul. 11,
2007, both incorporated herein by reference.
[0044] An Inconel.TM. tube (5/8 inch OD (1.59 cm)) is charged with
chromium oxide pellets (5 cc, 7.18 g, 12-20 mesh (1.68-0.84 mm)).
The chromium oxide is prepared by the pyrolysis of ammonium
dichromate as described in U.S. Pat. No. 5,036,036, herein
incorporated by reference. The chromium oxide has an
alpha-Cr.sub.2O.sub.3 structure and contains less than about 100
ppm of alkali metals; the surface area is about 40-60 m.sup.2/gm.
The chromium oxide is activated according to the following
sequence: (1) heating to 200.degree. C. for 15 minutes under a
purge of N.sub.2 (50 sccm, 8.33.times.10.sup.-7 m.sup.3/s) and then
increasing the temperature to 400.degree. C. over 30 minutes, (2)
lowering the temperature to 300.degree. C. for 35 minutes, (3)
flowing N.sub.2 (35 sccm, 5.83.times.10.sup.-7 m.sup.3/s) and HF
(12 sccm, 2.00.times.10.sup.-7 m.sup.3/s) for 35 minutes and then
increasing the temperature to 350.degree. C. for 60 minutes,
followed by 375.degree. C. for 90 minutes, followed by 400.degree.
C. for 30 minutes, and finally 425.degree. C. for 40 minutes, (4)
while maintaining the temperature at 425.degree. C., the flow of
N.sub.2 is reduced to 25 sccm (4.17.times.10.sup.-7 m.sup.3/s) and
HF is increased to 20 sccm (3.33.times.10.sup.-7 m.sup.3/s) for 20
minutes, (5) while maintaining the temperature at 425.degree. C.,
the flow of N.sub.2 is reduced to 15 sccm (2.50.times.10.sup.-7
m.sup.3/s) and HF is increased to 28 sccm (4.67.times.10.sup.-7
m.sup.3/s) for 20 minutes, (6) while maintaining the temperature at
425.degree. C., the flow of N.sub.2 is reduced to 5 sccm
(8.33.times.10.sup.-8 m.sup.3/s) and HF is increased to 36 sccm
(6.00.times.10.sup.-7 m.sup.3/s) for 20 minutes. The flow of HF is
then stopped and the reactor tube cooled to about 350.degree. C.
under a nitrogen flow. HFC-236cb and nitrogen are then passed
through the catalyst bed at about 21 sccm (3.5.times.10.sup.-7
m.sup.3/s) and 5.0 sccm (8.33.times.10.sup.-8 m.sup.3/s),
respectively; contact time of the HFC-236cb with the catalyst is
about 30 seconds. Analysis of the reactor effluent shows
approximately 60 GC area % HFC-236cb, 32 GC area % Z-HFC-1225ye, 4
GC area % E-HFC-1225ye, and 4 GC area % HFC-236ea.
* * * * *