U.S. patent application number 16/702225 was filed with the patent office on 2020-06-25 for catalysts and integrated processes for producing trifluoroiodomethane.
The applicant listed for this patent is Honeywell International Inc.. Invention is credited to Yuon Chiu, Christian Jungong, Haiyou Wang, Richard Wilcox, Terris Yang.
Application Number | 20200199049 16/702225 |
Document ID | / |
Family ID | 71074968 |
Filed Date | 2020-06-25 |
United States Patent
Application |
20200199049 |
Kind Code |
A1 |
Yang; Terris ; et
al. |
June 25, 2020 |
CATALYSTS AND INTEGRATED PROCESSES FOR PRODUCING
TRIFLUOROIODOMETHANE
Abstract
The present disclosure provides a process for producing
trifluoroiodomethane (CF.sub.3I). The process may include providing
a vapor-phase reactant stream comprising trifluoroacetic acid and
iodine and reacting the reactant stream in the presence of a
catalyst to produce a product stream comprising the
trifluoroiodomethane. The catalyst includes silicon carbide.
Inventors: |
Yang; Terris; (East Amherst,
NY) ; Wang; Haiyou; (Amherst, NY) ; Chiu;
Yuon; (Denville, NJ) ; Wilcox; Richard; (West
Caldwell, NJ) ; Jungong; Christian; (Depew,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Honeywell International Inc. |
Morris Plains |
NJ |
US |
|
|
Family ID: |
71074968 |
Appl. No.: |
16/702225 |
Filed: |
December 3, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62783412 |
Dec 21, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07C 2527/22 20130101;
C07C 19/16 20130101; B01J 27/224 20130101; C07C 17/093 20130101;
C07C 17/093 20130101; C07C 19/16 20130101 |
International
Class: |
C07C 17/093 20060101
C07C017/093; C07C 19/16 20060101 C07C019/16 |
Claims
1. A process for producing trifluoroiodomethane (CF.sub.3I), the
process comprising: providing a vapor-phase reactant stream
comprising trifluoroacetic acid and iodine; and reacting the
reactant stream in the presence of a catalyst to produce a product
stream comprising the trifluoroiodomethane, the catalyst comprising
silicon carbide.
2. The process of claim 1, wherein in the providing step, the
trifluoroacetic acid comprises less than about 500 ppm by volume of
water.
3. The process of claim 1, wherein in the providing step, the
iodine comprises less than about 500 ppm by weight of water.
4. The process of claim 1, wherein in the providing step, a mole
ratio of the iodine to the trifluoroacetic acid is from about 0.1:1
to about 2:1.
5. The process of claim 1, wherein the catalyst further comprises a
metal carbide.
6. The process of claim 5, wherein the metal carbide is titanium
carbide.
7. The process of claim 1, wherein the catalyst further comprises
at least one selected from the group of a metal and a metal salt
deposited on a surface of the catalyst.
8. The process of claim 7, wherein the metal or metal salt is from
about 0.1 wt. % to about 25 wt. % of the total weight of the
catalyst.
9. The process of claim 7, wherein the metal salt comprises at
least one selected from the group of potassium iodide, copper
iodide, and rubidium iodide.
10. The process of claim 1, wherein in the reacting step, a contact
time of the reactant stream with the catalyst is from about 1
second to about 120 seconds.
11. The process of claim 1, further comprising heating the catalyst
to a temperature from about 200.degree. C. to about 600.degree. C.
before the reacting step.
12. The process of claim 1, wherein the product stream further
comprises unreacted iodine and the process further comprises the
additional steps of: separating the unreacted iodine from the
product stream as solid iodine; heating the solid iodine to produce
liquid iodine; and returning the liquid iodine to the reactant
stream.
13. The process of claim 11, wherein the process is a continuous
process.
14. The process of claim 11, wherein the product stream further
comprises unreacted trifluoroacetic acid and the process further
comprises the additional steps of: separating the trifluoroacetic
acid from the product stream; and returning the separated
trifluoroacetic acid to the reactant stream.
15. A process for producing trifluoroiodomethane (CF.sub.3I), the
process comprising the following steps: reacting trifluoroacetic
acid and iodine in the vapor phase in the presence of a catalyst to
produce a product stream comprising the trifluoroiodomethane and
unreacted iodine, the catalyst comprising silicon carbide; removing
at least some of the unreacted iodine from the product stream by
cooling the product stream to form solid iodine, the solid iodine
forming in one of: a first iodine removal vessel; or a second
iodine removal vessel; producing liquid iodine from the solid
iodine by: heating the first iodine removal vessel to liquefy the
solid iodine when cooling the product stream through the second
iodine removal vessel; or heating the second iodine removal vessel
to liquefy the solid iodine when cooling the product stream through
the first iodine removal vessel; and recycling the liquified iodine
to the reacting step.
16. The process of claim 15, wherein the product stream further
comprises unreacted trifluoroacetic acid and the process further
comprises the additional steps of: separating the trifluoroacetic
acid from the product stream; and recycling the separated
trifluoroacetic acid to the reacting step.
17. The process of claim 15, wherein the process is a continuous
process.
18. The process of claim 15, wherein the catalyst further comprises
a metal carbide.
19. The process of claim 15, wherein the catalyst further comprises
at least one selected from the group of a metal and a metal salt
deposited on a surface of the catalyst.
20. The process of claim 19, wherein catalyst comprises a metal
salt comprising at least one selected from the group of potassium
iodide, copper iodide, and rubidium iodide.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional
Application No. 62/783,412, filed Dec. 21, 2018, which is herein
incorporated by reference in its entirety.
FIELD
[0002] The present disclosure relates to processes for producing
trifluoroiodomethane (CF.sub.3I). Specifically, the present
disclosure relates to catalysts and integrated processes to produce
trifluoroiodomethane.
BACKGROUND
[0003] Trifluoroiodomethane (CF.sub.3I) is a useful compound in
commercial applications, as a refrigerant or a fire suppression
agent, for example. Trifluoroiodomethane is an environmentally
acceptable compound with a low global warming potential and a low
ozone depletion potential. Trifluoroiodomethane can replace more
environmentally damaging materials.
[0004] Methods of preparing trifluoroiodomethane from
trifluoroacetic acid and elemental iodine are known. For example,
Kyong-Hwan Lee et al., "Synthesis of CF.sub.3I by Direct Iodination
of CF.sub.3COOH on Solid Catalyst," discloses a vapor phase
reaction of TFA and I.sub.2 to produce CF.sub.3I. TFA liquid is
metered into a three-necked flask containing iodine and heated to
vaporize the iodine. Together, the TFA and iodine vapors flow to a
reactor charged with a solid catalyst. The output of the reactor
flows into a heated collector, and then through a heated line, to a
second collector. The vapor stream including the CF.sub.3I flows
through a basic solution to neutralize acids. Thus, Lee discloses a
batch process, with a fixed quantity of I.sub.2 vaporized together
with a fixed quantity of TFA. Lee discloses that catalysts with
activated carbon are better than alumina.
[0005] U.S. Pat. No. 8,722,945 to Yang et al. discloses a vapor
phase reaction of a precursor, such as TFA, with a source of
iodine, such as I.sub.2, to produce a fluoroiodoalkane, such as
CF.sub.3I. The process may be a batch process or a continuous
process. The patent discloses methods for pretreating a solid
catalyst and regenerating the solid catalyst. The solid catalyst
may include an alkali metal, an alkaline earth metal, transition
metals, lanthanides or rare earth metals, including various metal
salts. The solid catalyst may be supported on an activated carbon
substrate.
[0006] U.S. Pat. No. 8,8871,986 to Yang et al. discloses a vapor
phase reaction of a precursor, such as TFA, with a source of
iodine, such as I.sub.2, to produce CF.sub.3I. The process may be a
batch process or a continuous process. The patent discloses various
catalyst promoters to promote catalyst activity and stability. The
catalysts include alkaline metals, alkaline earth metals, and salts
thereof supported by a carbonaceous carrier. Non-carbonaceous
carriers may also be employed.
[0007] U.S. Pat. No. 8,034,985 to Yang et al. discloses a vapor
phase reaction of a precursor, such as TFA, with a source of
iodine, such as I.sub.2, to produce a fluoroiodoalkane, such as
CF.sub.3I. The patent discloses various catalysts including
d.sub.1s.sup.1 and/or lanthanide elements. The catalysts can be
used in bulk or supported by activated carbon. Non-carbonaceous
carriers may also be employed.
[0008] The above references generally describe the use of activated
carbon as a catalyst support. While activated carbon catalysts may
afford excellent selectivity to producing CF.sub.3I, they are
susceptible to rapid deactivation as coke deposits accumulate on
the catalyst surface, decreasing the effective surface area of the
catalyst. In some cases, oxygen gas is co-fed with the reactants to
simultaneously remove the deposits by oxidation. However, the
oxygen gas may also lead to progressive reduction in the quantity
of carbon in the catalyst as the carbon in the catalyst combusts
during the reaction. The loss of carbon may adversely impact the
activity of the catalyst.
[0009] Thus, there is a need to develop a more durable catalyst
along with an efficient process that may be scaled to produce
commercial quantities of trifluoroiodomethane.
SUMMARY
[0010] The present disclosure provides integrated processes for
producing trifluoroiodomethane and a silicon carbide catalyst for
producing trifluoroiodomethane.
[0011] In one embodiment, the present invention provides a process
for producing trifluoroiodomethane (CF.sub.3I). The process
includes providing a vapor-phase reactant stream comprising
trifluoroacetic acid and iodine and reacting the reactant stream in
the presence of a catalyst to produce a product stream comprising
the trifluoroiodomethane. The catalyst includes silicon
carbide.
[0012] In another embodiment, the present invention provides a
process for producing trifluoroiodomethane (CF.sub.3I). The process
includes the steps of reacting trifluoroacetic acid and iodine in
the vapor phase in the presence of a catalyst to produce a product
stream including the trifluoroiodomethane and unreacted iodine,
removing at least some of the unreacted iodine from the product
stream by cooling the product stream to form solid iodine,
producing liquid iodine from the solid iodine, and recycling the
liquified iodine to the reacting step. The solid iodine may form in
one of a first iodine removal vessel or a second iodine removal
vessel. The liquid iodine may be produced by heating the first
iodine removal vessel to liquefy the solid iodine when cooling the
product stream through the second iodine removal vessel, or by
heating the second iodine removal vessels to liquefy the solid
iodine when cooling the product stream through the first iodine
removal vessel. The catalyst includes silicon carbide.
[0013] The above mentioned and other features of the disclosure,
and the manner of attaining them, will become more apparent and
will be better understood by reference to the following description
of embodiments taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The FIGURE is a process flow diagram showing an integrated
process for manufacturing trifluoroiodomethane.
DETAILED DESCRIPTION
[0015] The present disclosure provides integrated processes for the
manufacture of trifluoroiodomethane (CF.sub.3I) from
trifluoroacetic acid (TFA) and iodine (I.sub.2) that include the
use of a silicon carbide based catalyst. It has been found that use
of the silicon carbide based catalyst may provide for the efficient
manufacture of trifluoroiodomethane on a commercial scale. The
efficiency of the manufacture of trifluoroiodomethane is further
enhanced by the recycling the reactants. However, recycling iodine
presents challenges because it is solid below 113.7.degree. C. The
present disclosure also provides integrated processes for the
manufacture of trifluoroiodomethane that include recycling of
iodine in an efficient and continuous manner.
[0016] Catalysts including silicon carbide have been found to
provide useful alternative to catalysts including activated carbon.
Compared to activated carbon catalysts, silicon carbide catalysts
are more resistant to oxidation, more thermally stable, more
chemically inert, and less susceptible to deactivation. Silicon
carbide catalysts may be in the form of beads, pellets, extrudates,
powder, spheres, or mesh, for example. Silicon carbide exists in
two main forms: alpha silicon carbide and beta silicon carbide.
Either form may be used, but the beta silicon carbide is preferred
because it has a larger surface area per unit weight.
[0017] As disclosed herein, the trifluoroiodomethane is produced
from a reactant stream comprising trifluoroacetic acid (TFA) and
iodine (I.sub.2). The TFA and iodine are anhydrous. It is preferred
that there be as little water in the reactant stream as possible
because any water in the reactant stream may favor secondary
reaction pathways resulting in the formation of undesired
byproducts, such as trifluoromethane (CF.sub.3H).
[0018] The TFA is substantially free of water, including water by
weight in an amount less than about 1,000 parts per million (ppm),
about 500 ppm, about 300 ppm, about 200 ppm, about 100 ppm, about
50 ppm, about 30 ppm, about 20 ppm, or about 10 ppm, or less than
any value defined between any two of the foregoing values.
Preferably, the TFA comprises water by weight in an amount less
than about 100 ppm. More preferably, the TFA comprises water by
weight in an amount less than about 30 ppm. Most preferably, the
TFA comprises water by weight in an amount less than about 10
ppm.
[0019] The iodine is substantially free of water, including by
weight in an amount less than about 500 ppm, about 300 ppm, about
200 ppm, about 100 ppm, about 50 ppm, about 30 ppm, about 20 ppm,
or about 10 ppm, or less than any value defined between any two of
the foregoing values. Preferably, the iodine comprises water by
weight in an amount less than about 100 ppm. More preferably, the
iodine comprises water by weight in an amount less than about 30
ppm. Most preferably, the iodine comprises water by weight in an
amount less than about 10 ppm.
[0020] TFA is readily available in commercial quantities from
Halocarbon Products Corporation, Peachtree Corners, Ga., or from
Solvay S.A., Brussels, Belgium, for example. Solid iodine is
commercially available from SQM, Santiago, Chile, or Kanto Natural
Gas Development Co., Ltd, Chiba, Japan.
[0021] In the reactant stream, a mole ratio of iodine to TFA may be
as low as about 0.1:1, about 0.2:1, about 0.3:1, about 0.4:1, about
0.5:1, about 0.6:1, about 0.7:1, about 0.8:1, about 0.9:1, or about
1:1, or as high as about 1.1:1, about 1.2:1, about 1.3:1, about
1.4:1, about 1.5:1, about 1.6:1, about 1.8:1, about 2.0:1, about
2.5:1, about 3.0:1, about 3.5:1, about 4.0:1, about 4.5:1, or about
5.0:1, or within any range defined between any two of the foregoing
values, such as about 0.1:1 to about 5.0:1, about 0.5:1 to about
4.5:1, about 1:1 to about 4.0:1, about 1.5:1 to about 3.5:1, about
2.0:1 to about 3.0:1, about 0.9:1 to about 1.1:1, about 0.8:1 to
about 1.2:1, about 0.5:1 to about 1.5:1, about 1:1 to about 2:1,
about 0.8:1 to about 1.5:1, or about 0.9:1 to about 1.2:1, for
example. Preferably, the mole ratio of TFA to iodine is from about
0.8:1 to about 1.5:1. More preferably, the mole ratio of TFA to
iodine is from about 1:1 to about 1.2:1. Most preferably, the mole
ratio of TFA to iodine is from about 1:1 to about 1.1:1.
[0022] The reactant stream may react in the presence of a catalyst
contained within a reactor to produce a product stream comprising
trifluoroiodomethane and reaction by-products carbon dioxide
(CO.sub.2) and hydroiodic acid (HI) according to Equation 1
below:
CF.sub.3COOH+I.sub.2.fwdarw.CF.sub.3I+CO.sub.2+HI. Eq. 1:
[0023] The reactor may be a heated tube reactor, such a fixed bed
tubular reactor, including a tube containing the catalyst. The tube
may be made of a metal such as stainless steel, nickel, and/or a
nickel alloy, such as a nickel-molybdenum alloy, a
nickel-chromium-molybdenum alloy, or a nickel-copper alloy. The
tube reactor is heated, thus also heating the catalyst.
Alternatively, the reactor may be any type of packed reactor.
[0024] As noted above, the catalyst includes silicon carbide. The
catalyst may include essentially pure silicon carbide (SiC). The
catalyst may include a mixture of silicon carbide and one or more
metal carbides, such as titanium carbide (TiC), zirconium carbide
(ZrC), and/or chromium carbide (Cr.sub.3C.sub.2), for example. The
mixture of silicon carbide and one or more metal carbides is
referred to as a metal silicon carbide. The amount of silicon
carbide in metal silicon carbides, as a weight percentage of the
total silicon carbide and metal carbide in the catalyst, may be as
little as about 50 weight percent (wt. %), about 60 wt. %, about 70
wt. %, about 80 wt. %, or about 85 wt. %, or as high as about 90
wt. %, about 95 wt. %, about 97 wt. %, about 99 wt. %, or about
99.9 wt. %, or within any range defined between any two of the
foregoing values, such as about 50 wt. % to about 99.9 wt. %, about
60 wt. % to about 99 wt. %, about 70 wt. % to about 97 wt. %, about
80 wt. % to about 95 wt. %, about 85 wt. % to about 90 wt. %, about
70 wt. % to about 99.9 wt. %, or about 85 wt. % to about 99.9 wt.
%, for example. Preferably, the amount of silicon carbide in the
metal silicon carbide is from about 50 wt. % to about 99.9 wt. %.
More preferably, the amount of silicon carbide in the metal silicon
carbide is from about 70 wt. % to about 99.9 wt. %. Most
preferably, the amount of silicon carbide in the metal silicon
carbide is from about 85 wt. % to about 99.9 wt. %.
[0025] The catalyst may have a surface area as small as about 10
square meters per gram (m.sup.2/g), about 15 m.sup.2/g, about 25
m.sup.2/g, about 40 m.sup.2/g, about 60 m.sup.2/g, or about 80
m.sup.2/g, or as large as about 100 m.sup.2/g, about 120 m.sup.2/g,
about 150 m.sup.2/g, about 200 m.sup.2/g, about 250 m.sup.2/g, or
about 300 m.sup.2/g, or within any range defined between any two of
the foregoing values, such as about 10 m.sup.2/g to about 300
m.sup.2/g, about 15 m.sup.2/g to about 250 m.sup.2/g, about 25
m.sup.2/g to about 200 m.sup.2/g, about 40 m.sup.2/g to about 150
m.sup.2/g, about 60 m.sup.2/g to about 120 m.sup.2/g, or about 80
m.sup.2/g to about 120 m.sup.2/g, for example. The surface area of
the catalyst is determined by the BET method per ISO 9277:2010.
[0026] The silicon carbide or metal silicon carbide catalyst may be
used alone, or may include additional metals or metal salts on the
surface of the catalyst to promote catalyst activity and stability.
The metals may include transition metals, such as palladium,
platinum, iron and nickel. The metal salts may include any salts of
alkaline metals, alkaline earth metals, transition metals, and
combinations thereof. Examples of metals and metal salts may
include potassium iodide, copper(I) iodide, copper(II) rubidium
iodide, sodium iodide, potassium fluoride, magnesium iodide,
platinum and palladium, for example. Metal salts are more preferred
than metals. Preferred metal salts include potassium iodide,
copper(I) iodide, and rubidium iodide.
[0027] The metal salt catalysts may be prepared by impregnating the
silicon carbide or metal silicon carbide with an aqueous solution
of the desired metal salt, and then drying. The metal salt catalyst
may then be treated with hot nitrogen in situ before contacting the
reactants.
[0028] The amount of additional metals or metal salts on the
surface of the catalyst, as a percentage of the total combined
weight of the silicon carbide or metal silicon carbide and the
metals or metal salts may be as little as about 0.1 weight percent
(wt. %), about 0.3 wt. %, about 0.5 wt. %, about 0.7 wt. %, about 1
wt. %, about 2 wt. %, or about 4 wt. % or as great as about 6 wt.
%, about 8 wt. %, about 10 wt. %, about 15 wt. %, about 20 wt. %,
or about 25 wt. %, or within any range defined between any two of
the foregoing values, such as about 0.1 wt. % to about 25 wt. %,
about 0.3 wt. % to about 20 wt. %, about 0.5 wt. % to about 15 wt.
%, about 0.7 wt. % to about 10 wt. %, about 1 wt. % to about 8 wt.
%, about 2 wt. % to about 6 wt. %, or about 1 wt. % to about 4 wt.
%, for example. Preferably, the amount of metal salts on the
surface of the catalyst is from about 1 wt. % to about 20 wt. %.
More preferably, the amount of metal salts on the surface of the
catalyst is from about 3 wt. % to about 15 wt. %. Most preferably,
the amount of metal salts on the surface of the catalyst is from
about 5 wt. % to about 10 wt. %.
[0029] The reactant stream may be in contact with the catalyst for
a contact time as short as about 1 second, about 2 seconds, about 4
seconds, about 6 seconds, about 8 seconds, about 10 seconds, about
15 seconds, about 20 seconds, about 25 seconds, or about 30
seconds, or as long as about 40 seconds, about 50 seconds, about 60
seconds, about 70 seconds, about 80 seconds, about 100 seconds or
about 120 seconds, or within any range defined between any two of
the foregoing values, such as about 2 seconds to about 120 seconds,
about 4 second to about 100 seconds, about 6 seconds to about 80
seconds, about 8 seconds to about 70 seconds, about 10 seconds to
about 60 seconds, about 15 seconds to about 50 seconds, about 20
seconds to about 40 seconds, about 20 seconds to about 30 seconds,
about 10 seconds to about 20 seconds, or about 100 seconds to about
120 seconds, for example. Preferably, the reactant stream is in
contact with the catalyst for a contact time from about 1 second to
about 100 seconds. More preferably, the reactant stream is in
contact with the catalyst for a contact time from about 2 seconds
to about 50 seconds. Most preferably, the reactant stream is in
contact with the catalyst for a contact time from about 3 seconds
to about 30 seconds.
[0030] Prior to the reaction, the catalyst may be heated to a
temperature as low as about 200.degree. C., about 250.degree. C.,
about 300.degree. C., about 325.degree. C., about 330.degree. C.,
about 340.degree. C., about 350.degree. C., or about 360.degree.
C., or to a temperature as high as about 370.degree. C., about
380.degree. C., about 390.degree. C., about 400.degree. C., about
450.degree. C., about 475.degree. C., about 500.degree. C., about
525.degree. C., about 550.degree. C., about 575.degree. C., or
about 600.degree. C., or within any range defined between any two
of the foregoing values, such as about 200.degree. C. to about
600.degree. C., about 325.degree. C. to about 400.degree. C., about
330.degree. C. to about 390.degree. C., about 340.degree. C. to
about 380.degree. C., about 350.degree. C. to about 370.degree. C.,
or about 340.degree. C. to about 360.degree. C., for example.
Preferably, the catalyst is heated to a temperature from about
300.degree. C. to about 500.degree. C. More preferably, the
catalyst is heated to a temperature from about 350.degree. C. to
about 450.degree. C. Most preferably, the catalyst is heated to a
temperature from about 375.degree. C. to about 420.degree. C.
[0031] Pressure is not critical. Convenient operating pressures
range from about 10 kPa to about 4,000 kPa, and preferably from
about 100 kPa to about 250 kPa.
[0032] As noted above, compared to activated carbon catalysts,
silicon carbide catalysts are less susceptible to deactivation.
However, eventually carbon deposits may accumulate on the catalyst
surface and diminish catalytic activity. The silicon carbide
catalysts may be regenerated by flowing oxygen gas or air thorough
the reactor at temperature range from about 300.degree. C. to about
600.degree. C. to remove the carbon deposits. The regeneration is
done when the reaction is stopped and reactants are not flowing
through the reactor.
[0033] The composition of the organic compounds in the product
stream exiting the reactor may be measured by gas chromatography
(GC) and gas chromatography-mass spectroscopy (GC-MS) analyses.
Graph areas provided by the GC analysis for each of the organic
compounds may be combined to provide a GC area percentage (GC area
%) of the total organic compounds for each of the organic compounds
as a measurement of the relative concentrations of the organic
compounds in the product stream.
[0034] The concentration of trifluoroiodomethane in the product
stream exiting the reactor, in GC area % of total organic
compounds, may be as low as about 10%, about 15%, about 20%, about
25%, about 30%, about 35%, about 40%, about 45%, about 50%, about
55% or about 60%, or may be as high as about 65%, about 70%, about
75%, about 80%, about 85%, about 90%, about 95%, about or 99% or
within any range defined between any two of the foregoing values,
such as about 10% to about 99%, about 20% to about 95%, about 30%
to about 90%, about 40% to about 85%, about 45% to about 80%, about
50% to about 75%, about 55% to about 70%, about 60% to about 65%,
about 90% to about 99% or about 95% to about 99%, for example.
Preferably, the concentration of trifluoroiodomethane in the
product stream is from about 30% to about 99%. More preferably, the
concentration of trifluoroiodomethane in the product stream is from
about 40% to about 99%. Most preferably, the concentration of
trifluoroiodomethane in the product stream is from about 50% to
about 99%.
[0035] The product stream may be directed from the reactor to an
iodine removal vessel in which the product stream is cooled to
allow unreacted iodine to condense to remove at least some of the
iodine from the product stream to be recycled as a reactant. The
product stream may be cooled to a temperature lower than the
boiling point of iodine, but above the melting point of iodine, to
recover the iodine in liquid form. Alternatively, or additionally,
the product stream leaving the reactor may be cooled to a
temperature lower than the melting point of iodine to recover the
iodine in solid form. The product stream may proceed from the
iodine removal vessel to one or more additional iodine removal
vessels to remove additional unreacted iodine for recycle.
[0036] The product stream may then be directed from the one or more
iodine removal vessels to a heavies distillation column to separate
higher boiling point compounds, such as unreacted TFA, and
byproducts such as pentafluoroiodoethane (C.sub.2F.sub.5I) and
hydrogen fluoride (HF) from lower boiling point compounds CF.sub.3I
and byproducts such as trifluoromethane (CF.sub.3H), hydrogen
iodide (HI), and carbon dioxide (CO.sub.2). The higher boiling
point compounds may be directed from a bottom stream of the heavies
distillation column to a TFA recycle distillation column to
separate the higher boiling point TFA from the lower boiling point
byproducts C.sub.2F.sub.5I and HF. The TFA from a bottom stream of
the TFA recycle distillation column may be recycled back to the
reactor. The overhead stream of the TFA recycle distillation column
including the C.sub.2F.sub.5I and HF may pass through a scrubber
including a basic solution to remove the HF, and the
C.sub.2F.sub.5I may be recovered as a byproduct, or burned in a
thermal oxidizer.
[0037] The overhead stream from the heavies distillation column
including the CF.sub.3I, CF.sub.3H, HI and CO.sub.2 may be directed
to a CF.sub.3H/CO.sub.2 removal distillation column to separate the
higher boiling point compounds CF.sub.3I and HI from the lower
boiling point compounds CF.sub.3H and CO.sub.2. The overhead stream
of the CF.sub.3H/CO.sub.2 removal distillation column may be
directed to a CF.sub.3H distillation column to separate the
CF.sub.3H from the CO.sub.2. The CF.sub.3H and/or the CO.sub.2 may
be collected as byproducts. Alternatively, the overhead stream from
the CF.sub.3H/CO.sub.2 removal distillation column may be burned by
a thermal oxidizer.
[0038] The bottom stream of the CF.sub.3H/CO.sub.2 removal
distillation column including the CF.sub.3I and HI may be directed
to a product distillation column to separate the CF.sub.3I product
from the HI. The HI in the overhead stream of the product
distillation column may be collected as a byproduct by passing
through a water scrubber to generate an HI aqueous solution, or by
compressing it to produce an anhydrous HI liquid. The CF.sub.3I may
be collected from the bottom stream of the product distillation
column. The recycle of the iodine and the TFA results in an
efficient process for producing CF.sub.3I.
[0039] The FIGURE is a process flow diagram showing an integrated
process 10 for manufacturing trifluoroiodomethane. As shown in the
FIGURE, the process 10 includes material flows of solid iodine 12
and liquid TFA 14. The solid iodine 12 may be continuously or
intermittently added to a solid storage tank 16. A constant flow of
solid iodine 18 is transferred by a solid conveying system (not
shown) from the solid storage tank 16 to an iodine liquefier 20
where the solid iodine is heated to above its melting point but
below its boiling point to maintain a level of liquid iodine in the
iodine liquefier 20. Liquid iodine 22 flows from the iodine
liquefier 20 to an iodine vaporizer 24. The iodine liquefier 20 may
be pressurized by an inert gas to drive the flow of liquid iodine
22. The inert gas may include nitrogen, argon, or helium, or
mixtures thereof, for example. The flow rate of the liquid iodine
22 may be controlled by a liquid flow controller 26. In the iodine
vaporizer 24, the iodine is heated to above its boiling point to
form a flow of iodine vapor 28.
[0040] Liquid TFA 14 may be provided to a TFA vaporizer 30, where
the TFA is heated to above its boiling point to provide a flow of
TFA vapor 32. The flow rate of the TFA vapor 32 may be controlled
by a gas flow controller 34. The flow of iodine vapor 28 and the
flow of TFA vapor 32 may be combined in a mixing valve 36 to form a
reactant stream 38. The reactant stream 38 may be provided to a
reactor 40.
[0041] The reactant stream 38 may react in the presence of a
catalyst 42 contained within the reactor 40 to produce a product
stream 44. The catalyst 42 may be any of the catalysts described
herein. The product stream 44 may include trifluoroiodomethane,
unreacted iodine, unreacted TFA, and reaction by-products such as
HI, CO.sub.2, CF.sub.3H, HF, and C.sub.2F.sub.5I, for example.
[0042] The product stream 44 may be provided to an upstream valve
46. The upstream valve 46 may direct the product stream 44 to an
iodine removal step. In this step, a first iodine removal train 48a
may include a first iodine removal vessel 50a and a second iodine
removal vessel 50b. The product stream 44 may be cooled in the
first iodine removal vessel 50a to a temperature below the boiling
point of the iodine to condense at least some of the iodine,
separating it from the product stream 44. The product stream 44 may
be further cooled in the first iodine removal vessel 50a to a
temperature below the melting point of the iodine to separate even
more iodine from the product stream 44, depositing at least some of
the iodine within the first iodine removal vessel 50a as a solid
and producing a reduced iodine product stream 52. The reduced
iodine product stream 52 may be provided to the second iodine
removal vessel 50b and cooled to separate at least some more of the
iodine from the reduced iodine product stream 52 to produce an
iodine-free product stream 54. The iodine-free product stream 54
may be provided to a heavies distillation column 60.
[0043] Although the first iodine removal train 48a consists of two
iodine removal vessels operating in a series configuration, it is
understood that the first iodine removal train 48a may include two
or more iodine removal vessels operation in a parallel
configuration, more than two iodine removal vessels operating in a
series configuration, and any combination thereof. It is also
understood that the first iodine removal train 48a may consist of a
single iodine removal vessel.
[0044] The iodine collected in the first iodine removal vessel 50a
may form a first iodine recycle stream 56a. Similarly, the iodine
collected in the second iodine removal vessel 50b may form a second
iodine recycle stream 56b. Each of the first iodine recycle stream
56a and the second iodine recycle stream 56b may be provided to the
iodine liquefier 20. Should the iodine be collected in liquid form,
the liquid iodine may be provided to the iodine liquefier 20
continuously. However, it may be preferred to collect the iodine in
solid form because the lower temperature will result in more
effective removal of the iodine from the product stream 44 and the
reduced iodine product stream 52.
[0045] In order to provide continuous operation while collecting
the iodine in solid form, the upstream valve 46 may be configured
to selectively direct the product stream 44 to a second iodine
removal train 48b. The second iodine removal train 48b may be
substantially as described above for the first iodine removal train
48a. Once either the first iodine removal vessel 50a or the second
iodine removal vessel 50b of the first iodine removal train 48a
accumulates enough solid iodine that it is beneficial to remove it,
the upstream valve 46 may be selected to direct the product stream
44 from the first iodine removal train 48a to the second iodine
removal train 48b. At about the same time, a downstream valve 58
configured to selectively direct the iodine-free product stream 54
from either of the first iodine removal train 48a or the second
iodine removal train 48b to the heavies distillation column 60 may
be selected to direct the iodine-free product stream 54 from the
second iodine removal train 48b to the heavies distillation column
60 so that the process of removing the iodine from the product
stream 44 to produce the iodine-free product stream 54 may continue
uninterrupted. Once the product stream 44 is no longer directed to
the first iodine removal train 48a, the first iodine removal vessel
50a and the second iodine removal vessel 50b of the first iodine
removal train 48a may be heated to above the melting point of the
iodine, liquefying the solid iodine so that it may flow through the
first iodine recycle stream 56a and the second iodine recycle
stream 56b of the first iodine removal train 48a to the iodine
liquefier 20.
[0046] As the process continues and either of the first iodine
removal vessel 50a or the second iodine removal vessel 50b of the
second iodine removal train 48b accumulates enough solid iodine
that it is beneficial to remove it, the upstream valve 46 may be
selected to direct the product stream 44 from the second iodine
removal train 48b back to the first iodine removal train 48a, and
the downstream valve 58 may be selected to direct the iodine
product stream 54 from the first iodine removal train 48a to the
heavies distillation column 60 so that the process of removing the
iodine from the product stream 44 to produce the iodine-free
product stream 54 may continue uninterrupted. Once the product
stream 44 is no longer directed to the second iodine removal train
48b, the first iodine removal vessel 50a and the second iodine
removal vessel 50b of the second iodine removal train 48b may be
heated to above the melting point of the iodine, liquefying the
solid iodine so that it may flow through the first iodine recycle
stream 56a and the second iodine recycle stream 56b of the second
iodine removal train 48b to the iodine liquefier 20. By continuing
to switch between the first iodine removal train 48a and the second
iodine removal train 48b, the unreacted iodine in the product
stream 44 may be efficiently and continuously removed and
recycled.
[0047] As described above, the liquid iodine may flow through the
first iodine recycle streams 56a and the second iodine recycle
streams 56b of the first iodine removal train 48a and the second
iodine removal train 48b to the iodine liquefier 20. Alternatively,
the liquid iodine may flow through the first iodine recycle streams
56a and the second iodine recycle streams 56b of the first iodine
removal train 48a and the second iodine removal train 48b to the
iodine vaporizer 24, bypassing the iodine liquefier 20 and the
liquid flow controller 26.
[0048] The heavies distillation column 60 may be configured for the
separation of organic heavies, such as unreacted TFA, and
byproducts C.sub.2F.sub.5I and HF from organic lights, such as
CF.sub.3I and byproducts CF.sub.3H, HI and CO.sub.2. A bottom
stream 62 including the organic heavies from the heavies
distillation column 60 may be provided to a TFA recycle column 64.
The TFA recycle column 64 may be configured for the separation of
the unreacted TFA from the byproducts C.sub.2F.sub.5I and HF. A
bottom stream 66 of the TFA recycle column 64 including the
unreacted TFA may be recycled back to the reactor 40.
Alternatively, the bottom stream 66 of the TFA recycle column 64
including the unreacted TFA may be recycled back to the TFA
vaporizer 30. An overhead stream 68 of the TFA recycle column 64
including the byproducts C.sub.2F.sub.5I and HF may be treated by a
caustic solution (not shown) to remove the HF and the
C.sub.2F.sub.5I may be burned in a thermal oxidizer (not
shown).
[0049] An overhead stream 70 including the organic lights from the
heavies distillation column 60 may be provided to a
CF.sub.3H/CO.sub.2 removal column 72. The CF.sub.3H/CO.sub.2
removal column 72 may be configured for the separation of the
byproducts CF.sub.3H and CO.sub.2 from the CF.sub.3I and the
byproduct HI. An overhead stream 74 of the CF.sub.3H/CO.sub.2
removal column 72 including the byproducts CF.sub.3H and CO.sub.2
may be provided to a CF.sub.3H column 76. The CF.sub.3H column 76
may be configured to separate the CF.sub.3H from the CO.sub.2. A
bottom stream 78 of the CF.sub.3H column 76 including the CO.sub.2
may be recovered as a byproduct. An overhead stream 80 of the
CF.sub.3H column including the CF.sub.3H may be recovered as a
byproduct. Alternatively, the overhead stream 74 of the
CF.sub.3H/CO.sub.2 removal column 72 including the byproducts
CF.sub.3H and CO.sub.2 may bypass the CF.sub.3H column 76 and be
burned in a thermal oxidizer (not shown).
[0050] A bottom stream 82 including the CF.sub.3I and the byproduct
HI from the CF.sub.3H/CO.sub.2 removal column 72 may be provided to
a product column 84. The product column 84 may be configured to
separate the CF.sub.3I from the HI. An overhead stream 86 of the
product column 84 including the HI may be compressed into liquid
HI, or treated by a water scrubber (not shown) to produce an HI
solution. The liquid HI or HI solution may be converted back to
iodine and recycled by any means commercially available. The
resulting product CF.sub.3I may be collected from a bottom stream
88 of the product column 84.
[0051] While this invention has been described as relative to
exemplary designs, the present invention may be further modified
within the spirit and scope of this disclosure. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains.
[0052] As used herein, the phrase "within any range defined between
any two of the foregoing values" literally means that any range may
be selected from any two of the values listed prior to such phrase
regardless of whether the values are in the lower part of the
listing or in the higher part of the listing. For example, a pair
of values may be selected from two lower values, two higher values,
or a lower value and a higher value.
Examples
Evaluation of SiC-Based Catalysts in the Manufacture of
CF.sub.3I
[0053] In the following Examples, the manufacture of
trifluoroiodomethane from TFA and iodine according to Equation 1
described above was demonstrated for a variety of SiC-based
catalysts. Vaporized TFA from a TFA vaporizer was fed into an
iodine vaporizer at a measured feed rate. The iodine vaporizer was
initially charged with 1,000 g of solid iodine. The temperature of
the iodine vaporizer was maintained at 150.degree. C. to
165.degree. C. to generate an iodine vapor which mixed with the TFA
vapor. The mixture of iodine vapor and TFA vapor was fed to a fixed
bed tubular reactor which was loaded with a specific SiC-based
catalyst preheated to a predetermined reaction temperature. The
reaction was carried out at atmospheric pressure. The reactor
effluent was passed through two iodine removal vessels in series to
collect unreacted iodine in solid form, and then fed to a deionized
water scrubber to capture unreacted TFA.
[0054] Periodically, samples were taken from the effluent of the
deionized water scrubber and the composition of the organic
compounds in the samples were measured by gas chromatography (GC).
Graph areas provided by the GC analysis for each of the organic
compounds were combined to provide a GC area percentage (GC area %)
of the total organic compounds for each of the organic compounds as
a measurement of the relative concentrations of the organic
compounds in the samples to determine the mol. % selectivity in the
production of the CF.sub.3I. At the end of the run time of the
reaction, the system was shut down and the weight loss of the
iodine vaporizer and the weight gain of the iodine removal vessels
were measured to determine a feed ratio of moles of iodine to moles
of TFA. A residence time in the reactor was calculated based on the
combined feed rates of the iodine and the TFA.
[0055] The results for each example are shown in Table 1. For each
Example, Table 1 shows the catalyst used, the BET surface area, the
catalyst preheat temperature, the feed rate of the TFA, the
reaction run time, the molar feed ratio of I.sub.2 to TFA, the
residence time, and the mol. % selectivity in the production of
CF.sub.3I at the end of the run.
TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 8 9 Catalyst SiC
TiC--SiC TiC--SiC SiC SiC SiC + SiC + SiC + SiC + Cul Kl Rbl Pd
Catalyst Loading (wt. %) 0 0 0 0 0 5 5 5 1 Surface Area (m.sup.2/g)
18 18 18 30 30 18 18 18 18 Preheat Temp. (.degree. C.) 400 350 400
350 400 400 400 400 400 TFA Feed Rate (g/hr.) 9.2 8.0 7.7 8.0 8.2
8.3 8.0 8.9 8.9 Run Time (hrs.) 18 24 22 9 18 38 48 16 26 Molar
Feed Ratio 1.14 1.18 1.16 1.19 1.03 0.98 0.97 0.94 1.08
(I.sub.2/TFA) Residence Time (sec.) 4.2 5.1 5.0 5.1 5.0 5.0 5.2 4.8
4.5 CF.sub.3I Selectivity (mol. %) 43.3 59.1 58.9 28.5 48.7 50.6
47.3 65.9 46.8
Aspects
[0056] Aspect 1 is a process for producing trifluoroiodomethane
(CF.sub.3I). The process includes providing a vapor-phase reactant
stream comprising trifluoroacetic acid and iodine, and reacting the
reactant stream in the presence of a catalyst to produce a product
stream comprising the trifluoroiodomethane. The catalyst includes
silicon carbide.
[0057] Aspect 2 is the process of Aspect 1, wherein in the
providing step, the trifluoroacetic acid comprises less than about
1,000 ppm by volume of water.
[0058] Aspect 3 is the process of Aspect 1, wherein in the
providing step, the trifluoroacetic acid comprises less than about
100 ppm by volume of water.
[0059] Aspect 4 is the process of Aspect 1, wherein in the
providing step, the trifluoroacetic acid comprises less than about
30 ppm by volume of water.
[0060] Aspect 5 is the process of Aspect 1, wherein in the
providing step, the trifluoroacetic acid comprises less than about
10 ppm by volume of water.
[0061] Aspect 6 is the process of any of Aspects 1-5, wherein in
the providing step, the iodine comprises less than about 500 ppm by
volume of water.
[0062] Aspect 7 is the process of any of Aspects 1-5, wherein in
the providing step, the iodine comprises less than about 100 ppm by
volume of water.
[0063] Aspect 8 is the process of any of Aspects 1-5, wherein in
the providing step, the iodine comprises less than about 30 ppm by
volume of water.
[0064] Aspect 9 is the process of any of Aspects 1-5, wherein in
the providing step, the iodine comprises less than about 10 ppm by
volume of water.
[0065] Aspect 10 is the process of any of Aspects 1-9, wherein in
the providing step, a mole ratio of the trifluoroacetic acid to the
iodine is from about 0.1:1 to about 5:1.
[0066] Aspect 11 is the process of any of Aspects 1-9, wherein in
the providing step, a mole ratio of the trifluoroacetic acid to the
iodine is from about 0.8:1 to about 1.5:1.
[0067] Aspect 12 is the process of any of Aspects 1-9, wherein in
the providing step, a mole ratio of the trifluoroacetic acid to the
iodine is from about 1:1 to about 1.2:1.
[0068] Aspect 13 is the process of any of Aspects 1-9, wherein in
the providing step, a mole ratio of the trifluoroacetic acid to the
iodine is from about 1:1 to about 1.1:1.
[0069] Aspect 14 is the process of any of Aspects 1-13, wherein the
catalyst further comprises a metal carbide.
[0070] Aspect 15 is the process of Aspect 14, wherein the metal
carbide includes at least one selected from a group of titanium
carbide, zirconium carbide, and chromium carbide.
[0071] Aspect 16 is the process of Aspect 15, wherein the metal
carbide includes titanium carbide.
[0072] Aspect 17 is the process of Aspect 15, wherein the metal
carbide consists essentially of titanium carbide.
[0073] Aspect 18 is the process of Aspect 15, wherein the metal
carbide consists of titanium carbide.
[0074] Aspect 19 is the process of Aspect 15, wherein the metal
carbide includes zirconium carbide.
[0075] Aspect 20 is the process of Aspect 15, wherein the metal
carbide consists essentially of zirconium carbide.
[0076] Aspect 21 is the process of Aspect 15, wherein the metal
carbide consists of zirconium carbide.
[0077] Aspect 22 is the process of Aspect 15, wherein the metal
carbide includes chromium carbide.
[0078] Aspect 23 is the process of Aspect 15, wherein the metal
carbide consists essentially of chromium carbide.
[0079] Aspect 24 is the process of Aspect 15, wherein the metal
carbide consists of chromium carbide.
[0080] Aspect 25 is the process of any of Aspects 14-24, wherein an
amount of silicon carbide in the catalyst, as a weight percentage
of the total silicon carbide and metal carbide in the catalyst is
from about 50 wt. % to about 99.9 wt. %.
[0081] Aspect 26 is the process of any of Aspects 14-24, wherein an
amount of silicon carbide in the catalyst, as a weight percentage
of the total silicon carbide and metal carbide in the catalyst is
from about 70 wt. % to about 99.9 wt. %.
[0082] Aspect 27 is the process of any of Aspects 14-24, wherein an
amount of silicon carbide in the catalyst, as a weight percentage
of the total silicon carbide and metal carbide in the catalyst is
from about 85 wt. % to about 99.9 wt. %.
[0083] Aspect 28 is the process of any of Aspects 1-27, wherein the
catalyst further comprises at least one selected from the group of
a metal and a metal salt deposited on a surface of the
catalyst.
[0084] Aspect 29 is the process of Aspect 28, wherein the catalyst
comprises a metal salt, the metal sale including at least one
selected from the group of potassium iodide, copper(I) iodide,
copper(II) rubidium iodide, sodium iodide, potassium fluoride,
magnesium iodide, platinum and palladium.
[0085] Aspect 30 is the process of Aspect 29, wherein the metal
salt includes potassium iodide.
[0086] Aspect 31 is the process of Aspect 29, wherein the metal
salt consists essentially of potassium iodide.
[0087] Aspect 32 is the process of Aspect 29, wherein the metal
salt consists of potassium iodide.
[0088] Aspect 33 is the process of Aspect 29, wherein the metal
salt includes copper(I) iodide.
[0089] Aspect 34 is the process of Aspect 29, wherein the metal
salt consists essentially of copper(I) iodide.
[0090] Aspect 35 is the process of Aspect 29, wherein the metal
salt consists of copper(I) iodide.
[0091] Aspect 36 is the process of Aspect 29, wherein the metal
salt includes rubidium iodide.
[0092] Aspect 37 is the process of Aspect 29, wherein the metal
salt consists essentially of rubidium iodide.
[0093] Aspect 38 is the process of Aspect 29, wherein the metal
salt consists of rubidium iodide.
[0094] Aspect 39 is the process of any of Aspects 28-38, wherein
the metals or metal salts on the surface of the catalyst, as a
percentage of the total combined weight of the silicon carbide or
metal silicon carbide and the metals or metal salts is from 0.1 wt.
% to about 25 wt. %.
[0095] Aspect 40 is the process of any of Aspects 28-38, wherein
the metals or metal salts on the surface of the catalyst, as a
percentage of the total combined weight of the silicon carbide or
metal silicon carbide and the metals or metal salts is from about 1
wt. % to about 20 wt. %.
[0096] Aspect 41 is the process of any of Aspects 28-38, wherein
the metals or metal salts on the surface of the catalyst, as a
percentage of the total combined weight of the silicon carbide or
metal silicon carbide and the metals or metal salts is from about 3
wt. % to about 15 wt. %.
[0097] Aspect 42 is the process of any of Aspects 28-38, wherein
the metals or metal salts on the surface of the catalyst, as a
percentage of the total combined weight of the silicon carbide or
metal silicon carbide and the metals or metal salts is from about 5
wt. % to about 10 wt. %.
[0098] Aspect 43 is the process of any of Aspects 1-42, wherein a
contact time of the reactant stream with the catalyst is from about
1 second to about 120 seconds.
[0099] Aspect 44 is the process of any of Aspects 1-42, wherein a
contact time of the reactant stream with the catalyst is from about
1 second to about 100 seconds.
[0100] Aspect 45 is the process of any of Aspects 1-42, wherein a
contact time of the reactant stream with the catalyst is from about
2 seconds to about 50 seconds.
[0101] Aspect 46 is the process of any of Aspects 1-42, wherein a
contact time of the reactant stream with the catalyst is from about
3 seconds to about 30 seconds.
[0102] Aspect 47 is the process of any of Aspects 1-46, further
comprising heating the catalyst to a temperature from about
200.degree. C. to about 600.degree. C. before the reacting
step.
[0103] Aspect 48 is the process of any of Aspects 1-46, further
comprising heating the catalyst to a temperature from about
300.degree. C. to about 500.degree. C. before the reacting
step.
[0104] Aspect 49 is the process of any of Aspects 1-46, further
comprising heating the catalyst to a temperature from about
350.degree. C. to about 450.degree. C. before the reacting
step.
[0105] Aspect 50 is the process of any of Aspects 1-46, further
comprising heating the catalyst to a temperature from about
375.degree. C. to about 425.degree. C. before the reacting
step.
[0106] Aspect 51 is the process of any of Aspects 1-50, wherein the
product stream further comprises unreacted iodine and the process
further comprises the additional steps of separating the unreacted
iodine from the product stream as solid iodine, heating the solid
iodine to produce liquid iodine, and returning the liquid iodine to
the reactant stream.
[0107] Aspect 52 is the process of any of Aspects 1-51, wherein the
process is a continuous process.
[0108] Aspect 53 is the process of any of Aspects 1-51, wherein the
process is a batch process.
[0109] Aspect 54 is the process of any of Aspects 1-53, wherein the
product stream further comprises unreacted trifluoroacetic acid and
the process further comprises the additional steps of separating
the trifluoroacetic acid from the product stream and returning the
separated trifluoroacetic acid to the reactant stream.
[0110] Aspect 55 a process for producing trifluoroiodomethane
(CF.sub.3I), the process including the steps of reacting
trifluoroacetic acid and iodine in the vapor phase in the presence
of a catalyst to produce a product stream comprising the
trifluoroiodomethane and unreacted iodine, the catalyst comprising
silicon carbide; removing at least some of the unreacted iodine
from the product stream by cooling the product stream to form solid
iodine, the solid iodine forming in a first iodine removal vessel
and/or a second iodine removal vessel; producing liquid iodine from
the solid iodine by heating the first iodine removal vessel to
liquefy the solid iodine when cooling the product stream through
the second iodine removal vessel or heating the second iodine
removal vessel to liquefy the solid iodine when cooling the product
stream through the first iodine removal vessel, and recycling the
liquified iodine to the reacting step.
[0111] Aspect 56 is the process of Aspect 55 product stream further
comprises unreacted trifluoroacetic acid and the process further
comprises the additional steps of separating the trifluoroacetic
acid from the product stream and recycling the separated
trifluoroacetic acid to the reacting step.
[0112] Aspect 57 is the process of either of Aspects 55 or 56,
wherein the process is a continuous process.
[0113] Aspect 58 is the process of either of Aspects 55 or 56,
wherein the catalyst further comprises a metal carbide.
[0114] Aspect 59 is the process of Aspect 58, wherein the metal
carbide includes at least one selected from a group of titanium
carbide, zirconium carbide, and chromium carbide.
[0115] Aspect 60 is the process of Aspect 59, wherein the metal
carbide includes titanium carbide.
[0116] Aspect 61 is the process of Aspect 59, wherein the metal
carbide consists essentially of titanium carbide.
[0117] Aspect 62 is the process of Aspect 59, wherein the metal
carbide consists of titanium carbide.
[0118] Aspect 63 is the process of Aspect 59, wherein the metal
carbide includes zirconium carbide.
[0119] Aspect 64 is the process of Aspect 59, wherein the metal
carbide consists essentially of zirconium carbide.
[0120] Aspect 65 is the process of Aspect 59, wherein the metal
carbide consists of zirconium carbide.
[0121] Aspect 66 is the process of Aspect 59, wherein the metal
carbide includes chromium carbide.
[0122] Aspect 67 is the process of Aspect 59, wherein the metal
carbide consists essentially of chromium carbide.
[0123] Aspect 68 is the process of Aspect 59, wherein the metal
carbide consists of chromium carbide.
[0124] Aspect 69 is the process of any of Aspects 58-68, wherein an
amount of silicon carbide in the catalyst, as a weight percentage
of the total silicon carbide and metal carbide in the catalyst is
from about 50 wt. % to about 99.9 wt. %.
[0125] Aspect 70 is the process of any of Aspects 58-68, wherein an
amount of silicon carbide in the catalyst, as a weight percentage
of the total silicon carbide and metal carbide in the catalyst is
from about 70 wt. % to about 99.9 wt. %.
[0126] Aspect 71 is the process of any of Aspects 58-68, wherein an
amount of silicon carbide in the catalyst, as a weight percentage
of the total silicon carbide and metal carbide in the catalyst is
from about 85 wt. % to about 99.9 wt. %.
[0127] Aspect 72 is the process of any of Aspects 55-71, wherein
the catalyst further comprises at least one selected from the group
of a metal and a metal salt deposited on a surface of the
catalyst.
[0128] Aspect 73 is the process of Aspect 72, wherein the catalyst
comprises a metal salt, the metal sale including at least one
selected from the group of potassium iodide, copper(I) iodide,
copper(II) rubidium iodide, sodium iodide, potassium fluoride,
magnesium iodide, platinum and palladium.
[0129] Aspect 74 is the process of Aspect 73, wherein the metal
salt includes potassium iodide.
[0130] Aspect 75 is the process of Aspect 73, wherein the metal
salt consists essentially of potassium iodide.
[0131] Aspect 76 is the process of Aspect 73, wherein the metal
salt consists of potassium iodide.
[0132] Aspect 77 is the process of Aspect 73, wherein the metal
salt includes copper(I) iodide.
[0133] Aspect 78 is the process of Aspect 73, wherein the metal
salt consists essentially of copper(I) iodide.
[0134] Aspect 79 is the process of Aspect 73, wherein the metal
salt consists of copper(I) iodide.
[0135] Aspect 80 is the process of Aspect 73, wherein the metal
salt includes rubidium iodide.
[0136] Aspect 81 is the process of Aspect 73, wherein the metal
salt consists essentially of rubidium iodide.
[0137] Aspect 82 is the process of Aspect 73, wherein the metal
salt consists of rubidium iodide.
[0138] Aspect 83 is the process of any of Aspects 72-82, wherein
the metals or metal salts on the surface of the catalyst, as a
percentage of the total combined weight of the silicon carbide or
metal silicon carbide and the metals or metal salts is from 0.1 wt.
% to about 25 wt. %.
[0139] Aspect 84 is the process of any of Aspects 72-82, wherein
the metals or metal salts on the surface of the catalyst, as a
percentage of the total combined weight of the silicon carbide or
metal silicon carbide and the metals or metal salts is from about 1
wt. % to about 20 wt. %.
[0140] Aspect 85 is the process of any of Aspects 72-82, wherein
the metals or metal salts on the surface of the catalyst, as a
percentage of the total combined weight of the silicon carbide or
metal silicon carbide and the metals or metal salts is from about 3
wt. % to about 15 wt. %.
[0141] Aspect 86 is the process of any of Aspects 72-82, wherein
the metals or metal salts on the surface of the catalyst, as a
percentage of the total combined weight of the silicon carbide or
metal silicon carbide and the metals or metal salts is from about 5
wt. % to about 10 wt. %.
* * * * *