U.S. patent application number 12/534323 was filed with the patent office on 2011-02-03 for hydrogenation catalyst.
This patent application is currently assigned to HONEYWELL INTERNATIONAL INC.. Invention is credited to DANIEL C. MERKEL, HSUEH SUNG TUNG, HAIYOU WANG.
Application Number | 20110028770 12/534323 |
Document ID | / |
Family ID | 43527634 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110028770 |
Kind Code |
A1 |
WANG; HAIYOU ; et
al. |
February 3, 2011 |
HYDROGENATION CATALYST
Abstract
An alpha-alumina support for a hydrogenation catalyst useful in
hydrogenating fluoroolefins is provided.
Inventors: |
WANG; HAIYOU; (AMHERST,
NY) ; TUNG; HSUEH SUNG; (GETZVILLE, NY) ;
MERKEL; DANIEL C.; (WEST SENECA, NY) |
Correspondence
Address: |
HONEYWELL/FOX ROTHSCHILD;Patent Services
101 Columbia Road
Morristown
NJ
07962
US
|
Assignee: |
HONEYWELL INTERNATIONAL
INC.
MORRISVILLE
NJ
|
Family ID: |
43527634 |
Appl. No.: |
12/534323 |
Filed: |
August 3, 2009 |
Current U.S.
Class: |
570/176 ;
502/332; 502/333; 502/334; 502/335; 502/336; 502/344; 502/346;
502/348; 502/355 |
Current CPC
Class: |
B01J 23/36 20130101;
B01J 23/40 20130101; B01J 23/70 20130101; B01J 23/48 20130101; B01J
37/18 20130101; B01J 23/44 20130101; C07C 17/354 20130101; B01J
35/1014 20130101; B01J 21/04 20130101; C07C 17/354 20130101; C07C
19/08 20130101 |
Class at
Publication: |
570/176 ;
502/333; 502/334; 502/336; 502/335; 502/332; 502/346; 502/348;
502/344; 502/355 |
International
Class: |
B01J 21/04 20060101
B01J021/04; C07C 19/08 20060101 C07C019/08 |
Claims
1. A composition comprising: a. about 90 to about 99.9 of alumina,
wherein said alumina is at least about 90 wt. % alpha-alumina; and
b. about 0.1 to about 10 weight percent of at least one zero-valent
metal, wherein said zero-valent metal is selected from the group
consisting of Pd, Ru, Pt, Rh, Ir, Fe, Co, Ni, Cu, Ag, Re, Os, and
Au.
2. An article of manufacture comprising a supported hydrogenation
catalyst, wherein said supported hydrogenation catalyst comprises:
a. a support comprising alpha-alumina and having at least one
surface, and b. at least one zero-valent metal disposed on at least
a portion of said surface, wherein said zero-valent metal is
present in an amount from about 0.1 to about 10 weight percent
based upon the total weight of the support and reduced zero-valent
metal.
3. The article of claim 2 wherein said zero-valent metal is
selected from the group consisting of Pd, Ru, Pt, Rh, Ir, Fe, Co,
Ni, Cu, Ag, Re, Os, and Au.
4. The article of claim 2 wherein said support comprises at least
about 50 wt. % alpha-alumina.
5. The article of claim 2 wherein said support comprises at least
about 75 wt. % alpha-alumina.
6. The article of claim 2 wherein said support consists essentially
of said alpha-alumina.
7. The article of claim 6 wherein said zero-valent metal is
selected from the group consisting of Pd, Ru, Pt, Rh, Ir, Fe, Co,
Ni, Cu, Ag, Re, Os, and Au
8. The article of claim 7 wherein said metal is Pd.
9. The article of claim 2 wherein said metal comprises about 0.1 to
about 5 weight percent of the combined weight of said catalyst and
said support.
10. The article of claim 5 wherein said metal comprises about 0.1
to about 1 weight percent of the combined weight of said catalyst
and said support.
11. A method for preparing a catalyst comprising: a. adding at
least one metal salt, at least one solvent, and alpha-alumina
together to form a catalyst precursor composition; b. removing said
solvent from said catalyst precursor composition to form a dried
catalyst precursor composition; c. optionally calcining said dried
catalyst precursor composition; and d. contacting said dried
catalyst precursor composition with a gaseous composition
comprising H.sub.2 to form an activated supported catalyst
comprises about 90 to about 99.9 weight percent dehydrated
alpha-alumina and about 0.1 to about 10 weight percent of a
zero-valent metal derived from said metal salt.
12. The method of claim 11 wherein said catalyst precursor
composition is a slurry comprising alpha-alumina powder in a
solution of said metal salt and said solvent, said dried catalyst
precursor composition is a powder, and further comprising the steps
of transforming said powder into a pre-activated supported catalyst
prior to said contacting.
13. The method of claim 11 wherein said alpha-alumina is in the
form of pellets or spheres and wherein said adding comprises
soaking said pellets or spheres a solution comprising said metal
salt dissolved in said solvent.
14. A method for hydrogenating a compound comprising: contacting a
reactant comprising an olefin, wherein said olefin has at least one
carbon-fluorine bond, with a supported hydrogenation catalyst under
reaction conditions effective to form a reaction product comprising
a hydrogenated derivative of said olefin; wherein said supported
hydrogenation catalyst comprises a zero-valent metal disposed on a
support comprising alpha-alumina.
15. The method of claim 14 wherein said olefin is selected from the
group consisting of C.sub.2-C.sub.5 fluoroolefins and
C.sub.2-C.sub.5 hydrofluoroolefins and said hydrogenated derivative
of said olefin is a C.sub.2-C.sub.5 hydrofluoroalkane.
16. The method of claim 14 wherein said support comprises at least
about 50 wt. % alpha-alumina.
17. The method of claim 14 wherein said support comprises at least
about 75 wt. % alpha-alumina.
18. The method of claim 14 wherein zero-valent metal is selected
from the group consisting of Pd, Ru, Pt, Rh, Ir, Fe, Co, Ni, Cu,
Ag, Re, Os, and Au.
19. The method of claim 14 wherein said contacting comprises
feeding said olefin into a first stage of a hydrogenation reactor
at a rate resulting in a conversion of the feed olefin of from
about 10% to about 60%.
20. The method of claim 19 wherein said reaction product further
comprises at least a portion of said olefin from said reactant that
remains unreacted subsequent to said contacting; and wherein said
method further comprises converting, in one or more subsequent
stages of said hydrogenation reactor, about 20 to about 100 percent
of said olefin in said reaction product into said hydrogenated
derivative of said olefin.
Description
BACKGROUND
[0001] 1. Field of Invention
[0002] The present invention relates to catalysts for hydrogenating
olefins. More particularly, this invention relates to supported
catalyst for hydrogenating fluoroolefins.
[0003] 2. Description of Prior Art
[0004] Catalytic hydrogenation of fluoroolefins is frequently used
in producing hydrofluorocarbons as useful products and/or
intermediates. Various metals, such as Pd, supported on a substrate
have long been recognized as highly effective hydrogenation
catalysts. These catalysts are particularly effective in gas-phase
reactions. Alumina is known as a support for these catalysts.
Alumina has several different phases, typically designated by
different Greek letters, e.g., alpha (.alpha.) (also known as
corundum), beta (.beta.), chi (.chi.), kappa (.kappa.), eta
(.eta.), theta (.theta.), delta (.delta.), and gamma (.lamda.).
Each has a unique crystal structure and properties. For example,
alpha alumina is composed of hexagonal crystals, whereas gamma
alumina is composed of cubic crystals.
(http://www.infoplease.com/ce6/sci/A0803541.html).
[0005] Aluminas other than alpha phase alumina are known as
transitional phases because they can be transformed to the alpha
form at high temperatures. Id. Other forms of alumina include
amorphous alumina (that is, alumina lacking a crystalline
structure) and activated alumina which is a highly porous form of
dehydrated alumina that has a large specific surface area--often
significantly over 200 square
meters/g.(http://en.wikipedia.org/wiki/Activated_alumina).
[0006] Typically, preferred supports are characterized by a high
specific surface area. For example, U.S. Pat. No. 2,657,980 states
that "[i]n contrast with activated alumina is the well-known form
of alumina known as corundum [alpha-alumina], which is not
microporous and is unsuitable for [use as a hydrogenation
catalyst]." See also, U.S. Pat. No. 2,908,654 (Stating that, "It
has not been feasible to employ corundum (sometimes called alpha
alumina) as a carrier for highly reactive reforming catalyst, and
in order to distinguish from corundum, catalyst carrier grades are
designated by terms such as activated alumina, sorptive alumina or
gamma alumina.") Amorphous alumina has also been reported as a
support for hydrogenation catalysts. (U.S. Pat. No. 2,875,158).
[0007] Low concentration palladium/silver catalysts supported on
alpha-alumina have been reported as hydrogenation catalyst for
selectively hydrogenating acetylene. (U.S. Pat. No. 4,404,124) In
contrast, other phases of alumina have been reported as
hydrogenation catalyst for alkenes, particularly fluoroalkenes. For
example, I. L. Knunyants and E. I. Mysov (Kinetika i Kataliz, Vol.
8, No. 4, pp. 834-840) reported a Pd/Al.sub.2O.sub.3 catalyst with
a specific surface of about 200 m.sup.2/g for the hydrogenation of
CF.sub.2.dbd.CF.sub.2 to CHF.sub.2CHF.sub.2, and
CF.sub.3CF.dbd.CF.sub.2 (HFP) to CF.sub.3CHFCHF.sub.2 (236ea).
Based on the surface area information, the alumina used in this
catalyst can be one of transition aluminas.
[0008] However, due to the occurrence of hydrogenolytic cleavage of
the carbon-fluorine bond, a small amount of HF is generated during
hydrogenation of fluoroolefin which can attack the transition
alumina catalyst support causing catalyst structure change and
catalyst deactivation. Thus, all known transition alumina supports
for metal catalysts are inclined to be attacked by HF in the
hydrogenation of fluoroolefins, thereby limiting the useful
lifetime. Accordingly, there remains a need for a long-lived
catalyst support for a catalyst useful in hydrogenating
fluoroolefins. This invention satisfies this need among others.
SUMMARY OF THE INVENTION
[0009] Applicants unexpectedly found that metal catalysts supported
on alpha-alumina, which is the ultimate product of these transition
aluminas under high temperature calcination and is characterized by
small specific surface area (normally below 50 m.sup.2/g), provided
stable activity for the hydrogenation of fluoroolefins, while those
supported on transition alumina such as gamma-alumina exhibited
unstable activity.
[0010] Accordingly, in one aspect of the invention provided is a
composition comprising (a) about 90 to about 99.9 of alumina,
wherein said alumina is at least about 90 wt. % alpha-alumina; and
(b) about 0.1 to about 10 weight percent of at least one metal,
wherein said metal is selected from the group consisting of Pd, Ru,
Pt, Rh, Ir, Fe, Co, Ni, Cu, Ag, Re, Os, Au, and any combinations
thereof.
[0011] According to another aspect of the invention, provided is an
article of manufacture comprising a supported hydrogenation
catalyst, wherein said supported hydrogenation catalyst comprises
(a) a support comprising alpha-alumina and having at least one
surface, and (b) at least one zero-valent metal disposed on at
least a portion of said surface, wherein said zero-valent metal is
present in an amount from about 0.1 to about 10 weight percent
based upon the total weight of the support and reduced zero-valent
metal.
[0012] According to another aspect of the invention, provided is a
method for preparing a catalyst comprising (a) contacting at least
one metal salt, at least one solvent, and alpha-alumina to form a
slurry; (b) removing said solvent from said slurry to form a
solvent-free powder; (c) optionally calcining said powder; (d)
transforming said powder into a supported catalyst; and (e)
contacting said support catalyst with a gaseous composition
comprising H.sub.2 to activate said supported catalyst, wherein
said activated supported catalyst comprises about 90 to about 99.9
weight percent dehydrated alpha-alumina and about 0.1 to about 10
weight percent of a zero-valent metal derived from said metal salt.
In certain preferred embodiments, the method comprises the steps of
(a) dissolving a salt of metal component (e.g., Pd(NO.sub.3).sub.2,
PdCl.sub.2 for Pd) in a suitable solvent to form a solution; (b)
adding a suitable amount of alpha-alumina into said solution to
form a slurry; (c) driving off the solvent from said slurry to form
a paste; (d) drying said paste to form solvent-free powder; (e)
calcining said solvent-free powder in N.sub.2 flow for 2 to 8 hours
at 300-500.degree. C.; (f) grinding the calcined powder to a finely
divided state; (g) palletizing said fine powder into tablets; and
(h) reducing said catalyst pellets in H.sub.2 or diluted H.sub.2
flow for 2 to 4 hours at 150-250.degree. C. prior to use.
[0013] According to yet another aspect of the invention, provided
is a method for hydrogenating a compound comprising contacting a
reactant comprising an olefin, wherein said olefin has at least one
carbon-fluorine bond, with a supported hydrogenation catalyst under
reaction conditions effective to form a reaction product comprising
a hydrogenated derivative of said olefin; wherein said supported
hydrogenation catalyst comprises a zero-valent metal disposed on a
support comprising alpha-alumina. Preferably, the method involves
hydrogenating a fluoroolefin or hydrofluoroolefin, and more
preferably involves hydrogenating a fluoroolefin or
hydrofluoroolefin to produce a hydrofluoroalkane. In a preferred
embodiment, the method comprises the steps of (a) adding hydrogen
and a fluoroolefin to a reaction vessel containing a hydrogenation
catalyst; and (b) reacting said fluoroolefin with hydrogen over
said hydrogenation catalyst to produce a hydrofluorocarbon.
Non-limiting examples of hydrofluorocarbons that can be produced
through the hydrogenation of certain fluoroolefins include
1,1,1,2,3,3-hexafluoropropane (236ea), 1,1,1,2,3-pentafluoropropane
(245eb), 1,1,1,3,3-pentafluoropropane (245fa),
1,1,1,3-tetrafluoropropane (254fb), and 1,1,1,2-tetrafluoropropane
(254eb).
BRIEF DESCRIPTION OF THE DRAWING
[0014] FIG. 1 shows 1,1,1,2,3,3-hexafluoropropene (HFP) conversion
versus time on stream during HFP hydrogenation over 0.5 wt %
Pd/gamma-alumina and 0.5 wt % Pd/alpha-alumina catalysts.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0015] According to a preferred embodiment of the invention,
alpha-alumina supported metal catalysts are employed in the
hydrogenation of fluoroolefins to hydrofluorocarbons. Non-limiting
examples of metal components include Pd, Ru, Pt, Rh, Ir, Fe, Co,
Ni, Cu, Ag, Re, Os, Au, and any combinations thereof. The metal
loading can vary within a large range, e.g., from 0.1-10 wt %.
However, for noble metals such as Ru, Ph, Pd, Pt, Ir, etc., the
metal loading is preferably about 0.1 to about 5 wt %, and more
preferably about 0.1 to about 1 wt %. It has been discovered that
supported catalyst having metal concentrations below about 0.1 wt.
% are not highly effective at hydrogenating fluoroolefins or
hydrofluoroolefins.
[0016] In one embodiment, the salt of a metal component (e.g.,
Pd(NO.sub.3).sub.2 or PdCl.sub.2 for Pd) is added to an amount of
solvent sufficient to substantially dissolve or solubilize the
metal salt. The preferred solvent is one in which the metal salt is
readily soluble. The choice of solvent may vary depending on the
particular metal salts. Examples of solvents that can be used for
the preparation of the catalyst compositions of the present
invention include water, alcohols, ethers, and mixtures thereof.
Useful alcohols include monohydric and polyhydric alcohols. Most
preferred alcohols are those that are monohydric and have 1 to 5
carbon atoms. A most preferred solvent is water.
[0017] Desired amount of alpha-alumina powder is added to the
solution of said metal salt to form a slurry. After formation of
the slurry, substantially all of the solvent is removed to form a
solid mass of a mixture of said metal salt and said alpha-alumina.
Although the solvent can be removed in one step, a preferred method
is to drive off a portion of the solvent from the slurry to form a
paste and then followed by drying the paste to form the solid mass.
Any conventional technique can be used to drive off the solvent.
Examples of such techniques include vigorous stirring at room or
elevated temperatures, evaporation, settling and decanting,
centrifugation, and filtration. It is preferred to evaporate off a
desired amount of solvent to form the paste. The paste is then
dried by any suitable method to form a free-flowing, substantially
solvent-free powder. Preferred methods for drying include oven
drying, most preferably at temperatures from about 110.degree. C.
to about 120.degree. C., and spray drying. As used herein, the term
"solvent free" means that less than 1 wt. %, preferably about 0.5
wt % or less, more preferably about 0.1 wt % or less, and most
preferably no solvent will remain with the powder after solvent
removal/drying. Upon removal of solvent, the powder will take the
form of a solid mass (or powder) of a mixture of particles of said
metal salt and said alpha-alumina.
[0018] Optionally, the solid mass of the mixture of said metal salt
and said alpha-alumina powder is then calcined. Calcination is
preferably carried out at a temperature of about 100.degree. C. to
about 750.degree. C., more preferably at a temperature of about
200.degree. C. to about 600.degree. C., and most preferably at a
temperature of about 300.degree. C. to about 500.degree. C.
Calcination may further optionally be carried out in the presence
of an inert gas, such as nitrogen or argon.
[0019] After calcination, the powder is optionally further grinded
such that it becomes more finely-divided. The powder is further
optionally pelletized in order to form pellets.
[0020] The catalyst pellets are then loaded into a reactor and
prior to use are reduced in hydrogen or diluted hydrogen flow for
2-4 hours at a temperature of about 50 to about 500.degree. C.,
more preferably at a temperature of about 100 to about 300.degree.
C., and most preferably at a temperature of about 150 to about
250.degree. C.
[0021] Although it is contemplated that the hydrogenation of
fluoroolefins may be conducted in batch operation, it is preferred
that the hydrogenation reaction is carried out as a substantially
continuous operation. Furthermore, while it is possible that the
hydrogenation reaction may involve in certain embodiments a liquid
phase reaction, it is contemplated that in preferred embodiments
the hydrogenation reaction comprises, and even more preferably
consists of, at least two vapor phase reaction stages.
[0022] With respect to the number of reaction stages, applicants
have found surprisingly and unexpectedly that overall reaction
conversion and selectivity can be achieved at relatively high
levels by the use of at least two reaction stages wherein the first
stage of reaction is conducted under conditions effective to
achieve a first, relatively low rate of conversion to produce a
first stage reaction effluent, and at least a second stage of
reaction which is fed by at least a portion of said first stage
effluent and which is conducted under conditions effective to
achieve a second rate of conversion higher than said first rate.
Preferably, reaction conditions are controlled in each of the first
and second stages in order to achieve the desired conversion in
accordance with the present invention. As used herein, the term
"reaction conditions" is intended to include the singular and means
control of any one or more processing parameters which can be
modified by the operator of the reaction to produce the conversion
of the feed material in accordance with the teachings contained
herein. By way of example, but not by way of limitation, conversion
of the feed material may be controlled or regulated by controlling
or regulating any one or more of the following: the temperature of
the reaction, the flow rate of the reactants, the presence of
diluent, the amount of catalyst present in the reaction vessel, the
shape and size of the reaction vessel, the pressure of the
reaction, and any combinations of these and other process
parameters which will be available and known to those skilled in
the art in view of the disclosure contained herein.
[0023] Applicants have found that in preferred embodiments the step
of controlling the conversion in the first stage of the
hydrogenation reaction is achieved by judicious selection and
control of the amount of catalyst present in the first stage of
reaction relative to the feed rate of one or more of the reactants
and/or by judicious selection and control of the reaction
temperature, and preferably by judicious selection and control of
both of these process parameters. The step of judiciously selecting
the amount of catalyst to be used in the first stage of reaction
includes the step of estimating the amount of catalyst
theoretically needed to convert 100% of the feed material. Such an
estimate can be obtained by any and all known methods for making
such an estimate, which should be apparent to those skilled in the
art in view of the teachings contained herein. In addition, the
step of judiciously selecting the amount of catalyst may also
involve conducting bench, pilot or similar studies to determine the
amount of the particular catalyst being used which is needed to
convert 100% of the feed material under the feed rate in other
process parameters which have otherwise been chosen. Based upon
this estimate, the preferred embodiments of the present invention
then include the step of providing in the first stage of reaction
an amount of catalyst that is substantially below the amount
required for 100% conversion, and even more preferably is
sufficiently low so as to result in a conversion of the feed olefin
of from about 10% to about 60%, more preferably from about 10% to
about 40%, and even more preferably from about 10% to 25%. Once
again, those skilled in the art will appreciate that the step of
judiciously choosing the amount of catalyst may further include
running additional bench, pilot or other studies with the reduced
amount of catalyst and adjusting the amount of catalyst
accordingly. It is contemplated that all such studies and estimates
can be achieved without undue experimentation in view of the
teachings contained herein.
[0024] Applicants have found that the step of maintaining a
relatively low conversion of reactant in accordance with the
present invention in a first stage of reaction has an advantageous
affect on the selectivity of the reaction to the desired
hydrofluorocarbon. In other words, although the amount of
conversion which occurs in the first stage of reaction is
controlled to be well below that which is desired for the overall
hydrogenation step, applicants have found that an improved, higher
percentage of the feed material is converted to the desired
hydrofluorocarbon in the first reaction stage (that is, improved
selectivity is achieved) by controlling the conversion as described
herein. More specifically, it is preferred in many embodiments that
the selectivity to the desired hydrofluorocarbon in the first
reaction stage is at least about 80%, more preferably at least
about 90%, and even more preferably at least about 95%, and in many
preferred embodiments about 97% or greater.
[0025] In certain preferred embodiments the step of controlling the
conversion in the first reaction stage further includes removing
heat from the reaction by cooling at least a portion of the
reaction mixture. It is contemplated that those skilled in the art
will be able to devise without undue experimentation and many means
and mechanisms for attaining such cooling in view of the teachings
contained herein and all such means and mechanisms are with the
scope of the present invention.
[0026] In preferred embodiments, at least a portion of the effluent
from the first reaction stage is fed directly, or optionally after
some further processing, to a second reaction stage in which the
unreacted fluoroolefin remaining in the effluent after the first
reaction stage is converted to the hydrofluorocarbon in accordance
with the present invention. More specifically is preferred that the
second reaction stage or subsequent reaction stages if present, is
operated under conditions effective to convert the fluoroolefin
contained in the feed stream to the second reactor stage at a
conversion rate that is greater than, and preferably substantially
greater than, the conversion percentage in the first reaction
stage. In certain preferred embodiments, for example, the
conversion percentage in the second reaction stage is from about
20% to about 99%, depending in large part upon the total number of
reactant stages used to affect the overall conversion step. For
example, in embodiments consisting of a two-stage reaction system,
it is contemplated that the conversion in the second reaction stage
is preferably greater than 95%, and even more preferably about
100%. However, as those skilled in the art will appreciate from the
teachings contained herein, such a two-stage reaction may not be
sufficient to produce the desired selectivity to the
hydrofluorocarbon. In such cases, it is within the scope of the
present invention that the conversion step may comprise greater
than two reaction stages, including in some embodiments as many 10
or more reaction stages.
[0027] The size and shape, and other characteristics of the
reaction vessel itself may vary widely with the scope of the
present invention, and it is contemplated that the vessel
associated with each stage may be different than or the same as the
vessel associated with the upstream and downstream reaction stages.
Furthermore, it is contemplated that all reaction stages can occur
inside a single vessel, provided that means and mechanisms
necessary to control conversion are provided. For example, it may
be desirable in certain embodiments to utilize a single tubular
reactor for each reaction stage, providing conversion control by
judicious selection of the amount and/or distribution of catalyst
throughout the tubular reactor. In such a case, it is possible to
further control the conversion in different sections of the same
tubular reactor by controlling the amount of heat removed from or
added to different sections of the tubular reactor.
[0028] The catalyst compositions disclosed in the present invention
are useful in converting fluoroolefins to hydrofluorocarbons. The
catalysts are stable because of their resistance to HF attack and
can be re-used after regeneration. One or more of the hydrogenation
catalyst disclosed in the present invention may be used for one or
more of the reaction stages in accordance with the present
invention.
[0029] Thus, certain embodiments of the present methods comprise
bringing a fluoroolefin and a hydrogenation agent, such as H.sub.2,
into contact with a first amount of catalyst in a first reaction
stage to produce a reaction stream comprising hydrofluorocarbon(s),
unreacted fluoroolefin and hydrogen; contacting at least a portion
of this first effluent stream with a second amount of catalyst in a
second stage of reaction to produce a hydrofluorocarbon, wherein
the second amount of catalyst is greater than the first amount of
catalyst and wherein conversion to the fluoroolefin is higher in
the second stage of reaction.
[0030] Table 1 sets forth examples of hydrofluorocarbons and
fluoroolefins from which they can be obtained (fluoroolefin in left
column and corresponding hydrofluorocarbon in the right
column).
TABLE-US-00001 TABLE 1 Fluoroolefins Hydrofluorocarbons
1,1,2,3,3,3-hexafluoropropene 1,1,1,2,3,3-hexafluoropropane
CF.sub.3CF.dbd.CF.sub.2 (1216) CF.sub.3CHFCHF.sub.2 (236ea)
1,2,3,3,3-pentafluoropropene 1,1,1,2,3-pentafluoropropane
CF.sub.3CF.dbd.CHF (Z/E-1225ye) CF.sub.3CHFCH.sub.2F (245eb)
1,1,3,3,3-pentafluoropropene 1,1,1,3,3-pentafluoropropane
CF.sub.3CH.dbd.CF.sub.2 (1225zc) CF.sub.3CH.sub.2CHF.sub.2 (245fa)
1,3,3,3-tetrafluoropropene 1,1,1,3-tetrafluoropropane
CF.sub.3CH.dbd.CHF (trans/cis-1234ze) CF.sub.3CH.sub.2CH.sub.2F
(254fb) 2,3,3,3-tetrafluoropropene 1,1,1,2-tetrafluoropropane
CF.sub.3CF.dbd.CH.sub.2 (1234yf) CF.sub.3CHFCH.sub.3 (254eb)
EXAMPLES
[0031] The following are examples of the invention and are not to
be construed as limiting.
Example 1
Comparison of Gamma-Alumina and Alpha-Alumina Supported Pd
Catalysts for 1,1,1,2,3,3-hexafluoropropene hydrogenation
[0032] 0.5 wt % Pd/gamma-alumina and 0.5 wt % Pd/alpha-alumina,
which have a specific surface area of 243 and 33 m.sup.2/g,
respectively, were compared for 1,1,1,2,3,3-hexafluoropropene (HFP)
hydrogenation. About 2 g of catalyst diluted with 20 ml of Monel
packing was charged into a 3/4'' Monel tube reactor and was in-situ
reduced in 10% H.sub.2/N.sub.2 flow for 2 hours at 200.degree. C.
HFP was fed into reactor at a rate of 5 g/h, and H.sub.2 was co-fed
according to a mole ratio of H.sub.2/HFP equal to 1.5. As shown in
Table 2, both catalysts initially provided a near complete HFP
conversion and a 236ea selectivity of above 99.5%. Nevertheless, as
shown in FIG. 1, while no deactivation was noted over the 0.5 wt %
Pd/alpha-alumina catalyst even after 1000 h on stream, rapid
deactivation was observed over the 0.5 wt % Pd/gamma-alumina
beginning around 600 h on stream. This indicates that the
alpha-alumina supported Pd catalyst is much more stable than the
gamma-alumina supported Pd catalyst.
TABLE-US-00002 TABLE 2 HFP hydrogenation over alumina supported Pd
catalysts* Temp. Conversion, % Selectivity, % Selectivity, %
Catalyst (.degree. C.) HFP 236ea others 0.5% Pd/.gamma.- 100 99.9
99.6 0.4 alumina 0.5% Pd/.alpha.- 100 98.2 99.9 0.1 alumina *data
obtained after 2 h on stream.
Example 2
Hydrogenation of 1,1,1,2,3,3-hexafluoropropene Over Alpha-Alumina
Supported Pd Catalyst
[0033] 0.5 wt % Pd/alpha-alumina catalyst, which has a specific
surface area of 33 m.sup.2/g, was used for
1,1,1,2,3,3-hexafluoropropene (HFP) hydrogenation. About 1 g of
catalyst diluted with 10 ml of Monel packing was charged into a
3/4'' Monel tube reactor and was in-situ reduced in 10%
H.sub.2/N.sub.2 flow for 2 hours at 200.degree. C. HFP was fed into
reactor at a rate of 65 g/h, and H.sub.2 was co-fed according to a
mole ratio of H.sub.2/HFP equal to 1.5. GC analysis of the product
stream showed that the catalyst provided an HFP conversion of
around 55% and a 245eb selectivity of about 99.5%. No deactivation
was noted during the period of time of the test which lasted for
800 hours, indicating the alpha-alumina supported Pd catalyst can
provide stable activity for HFP hydrogenation.
Example 3
Hydrogenation of 1,1,1,2,3-pentafluoropropene Over Alpha-Alumina
Supported Pd Catalyst
[0034] 0.5 wt % Pd/alpha-alumina catalyst, which has a specific
surface area of 33 m.sup.2/g, was used for
1,1,1,2,3-pentafluoropropene (1225ye) hydrogenation. About 0.5 g of
catalyst diluted with 10 ml of Monel packing was charged into a
3/4'' Monel tube reactor and was in-situ reduced in 10%
H.sub.2/N.sub.2 flow for 2 hours at 200.degree. C. 1225ye was fed
into reactor at a rate of 30 g/h, and H.sub.2 was co-fed according
to a mole ratio of H.sub.2/1225ye equal to 1.5. GC analysis of the
product stream showed that the catalyst provided a 1225ye
conversion of around 45% and a 245eb selectivity of about 98.5%. No
deactivation was noted during the period of time of the test which
lasted for 800 hours, indicating the alpha-alumina supported Pd
catalyst can provide stable activity for 1225ye hydrogenation.
[0035] It should be understood that the foregoing description is
only illustrative of the present invention. Various alternatives
and modifications can be devised by those skilled in the art
without departing from the invention. Accordingly, the present
invention is intended to embrace all such alternatives,
modifications and variances that fall within the scope of the
appended claim.
* * * * *
References