U.S. patent application number 09/196347 was filed with the patent office on 2001-05-24 for hydrogenation catalysts and processes therewith.
This patent application is currently assigned to Phillips Petroleum Company. Invention is credited to BROWN, SCOTT H., CHEUNG, TIN-TACK PETER.
Application Number | 20010001805 09/196347 |
Document ID | / |
Family ID | 25197731 |
Filed Date | 2001-05-24 |
United States Patent
Application |
20010001805 |
Kind Code |
A1 |
BROWN, SCOTT H. ; et
al. |
May 24, 2001 |
HYDROGENATION CATALYSTS AND PROCESSES THEREWITH
Abstract
A composition and a process for using the composition in a
selective hydrogenation of a highly unsaturated hydrocarbon such
as, for example, an alkyne or diolefin, to a less unsaturated
hydrocarbon such as, for example, an alkene or a monoolefin, are
disclosed. The composition comprising palladium, a selectivity
enhancer and an inorganic support wherein the palladium and
selectivity enhancer are each present in a sufficient amount to
effect the selective hydrogenation of a highly unsaturated
hydrocarbon. Optionally, the composition can comprise silver. Also
optionally, the palladium is present as skin distributed on the
surface of the support. The composition can further comprise an
alkali metal-containing compound such as, for example, potassium
fluoride.
Inventors: |
BROWN, SCOTT H.;
(BARTLESVILLE, OK) ; CHEUNG, TIN-TACK PETER;
(BARTLESVILLE, OK) |
Correspondence
Address: |
LUCAS K SHAY
RICHMMOND HITCHCOCK FISH & DOLLAR
PO BOX 2443
BARTLESVILLE
OK
74005
|
Assignee: |
Phillips Petroleum Company
|
Family ID: |
25197731 |
Appl. No.: |
09/196347 |
Filed: |
November 19, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09196347 |
Nov 19, 1998 |
|
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08808047 |
Feb 27, 1997 |
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Current U.S.
Class: |
585/259 ;
208/143; 208/144; 208/145; 585/273; 585/274; 585/275; 585/277 |
Current CPC
Class: |
C07C 2521/04 20130101;
C07C 2521/08 20130101; C07C 2523/75 20130101; C07C 2523/12
20130101; C07C 2523/06 20130101; C07C 2523/50 20130101; C07C
2523/745 20130101; C07C 2527/12 20130101; C07C 2523/44 20130101;
B01J 23/44 20130101; C07C 5/02 20130101; C07C 2523/02 20130101;
B01J 23/56 20130101; C07C 2523/04 20130101; C07C 2521/06 20130101;
C07C 2523/28 20130101; C07C 2523/14 20130101; C07C 2521/10
20130101; C07C 2523/18 20130101; C07C 2523/34 20130101; C07C
2523/46 20130101; B01J 23/58 20130101 |
Class at
Publication: |
585/259 ;
585/273; 585/274; 585/275; 585/277; 208/143; 208/144; 208/145 |
International
Class: |
C07C 005/05 |
Claims
That which is claimed:
1. A composition comprising palladium, a selectivity enhancer, and
an inorganic support wherein said palladium and selectivity
enhancer are each present in a sufficient amount to effect a
selective hydrogenation of an unsaturated hydrocarbon, said
selectivity enhancer is selected from the group consisting of lead,
bismuth, thorium, iridium, gallium, tin antimony, germanium,
arsenic, cadmium, mercury, and combinations of any two or more
thereof, and said support is selected from the group consisting of
silica, alumina, spinel, and combinations of any two or more
thereof.
2. A composition according to claim 1 further comprising
silver.
3. A composition according to claim 1 further comprising an alkali
metal or an alkali metal-containing compound.
4. A composition according to claim 3 further comprising
silver.
5. A composition according to claim 3 wherein said alkali
metal-containing compound is an alkali metal halide.
6. A composition according to claim 4 wherein said alkali
metal-containing compound is an alkali metal halide.
7. A composition according to claim 1 wherein the metal of said
spinel is selected from the group consisting of zinc, magnesium,
calcium, beryllium, strontium, barium, radium, iron, manganese,
zirconium, molybdenum, ruthenium, rhodium, cobalt, germanium, tin,
and combinations of any two or more thereof.
8. A composition according to claim 1 wherein said selectivity
enhancer is lead.
9. A composition according to claim 2 wherein said selectivity
enhancer is lead.
10. A composition according to claim 1 wherein said selectivity
enhancer is bismuth.
11. A composition according to claim 2 wherein said selectivity
enhancer is bismuth.
12. A composition according to claim 1 wherein said selectivity
enhancer is gallium.
13. A composition according to claim 2 wherein said selectivity
enhancer is gallium.
14. A composition according to claim 1 wherein the weight % of said
palladium is in the range of from about 0.0001 to about 5%.
15. A composition according to claim 1 wherein the weight % of said
palladium is in the range of from 0.001 to 1.5%.
16. A composition according to claim 1 wherein the weight % of said
selectivity enhancer is in the range of from about 0.001 to about
10%.
17. A composition according to claim 1 wherein the weight % of said
selectivity enhancer is in the range of from 0.003 to 5%.
18. A composition according to claim 2 wherein the weight % of said
selectivity enhancer is in the range of from about 0.001 to about
10%.
19. A composition comprising palladium, a selectivity enhancer and
an inorganic support wherein said support is selected from the
group consisting of silica, alumina, spinel, and combinations of
any two or more thereof wherein the metal of said spinel is
selected from the group consisting of zinc, magnesium, calcium,
beryllium, strontium, barium, radium, iron, manganese, zirconium,
molybdenum, ruthenium, rhodium, cobalt, germanium, tin, and
combinations of any two or more thereof; the weight % of said
palladium is in the range of from about 0.0001 to about 5%; and the
weight ratio of selectivity enhancer to palladium is in the range
of from about 0.1:1 to about 20:1.
20. A composition according to claim 19 wherein said support is
alumina; the weight % of said palladium is in the range of from
about 0.001 to about 1.5%; and the weight ratio of selectivity
enhancer to palladium is in the range of from about 1:1 to about
10:1.
21. A composition according to claim 20 wherein said palladium is
present as skin distributed on the surface of said alumina and the
thickness of said skin is in the range of from 10 to about 300
.mu.m.
22. A composition according to claim 19 further comprising an
alkali metal fluoride.
23. A composition according to claim 19 further comprising
silver.
24. A composition according to claim 22 further comprising
silver.
25. A process comprising contacting a highly unsaturated
hydrocarbon, in the presence of hydrogen, with a composition under
a condition sufficient to effect selective hydrogenation of said
highly unsaturated hydrocarbon to a less unsaturated hydrocarbon
wherein said composition comprises palladium, selectivity enhancer
and an inorganic support; and said palladium and selectivity
enhancer are each present in a sufficient amount to effect
hydrogenation of an unsaturated hydrocarbon.
26. A process according to claim 25 wherein said composition
further comprises an alkali metal-containing compound.
27. A process according to claim 25 wherein said composition
further comprises silver.
28. A process according to claim 25 wherein said support is a
spinel and the metal of said spinel is selected from the group
consisting of zinc, magnesium, calcium, beryllium, strontium,
barium, radium, iron, manganese, zirconium, molybdenum, ruthenium,
rhodium, cobalt, germanium, tin, and combinations of any two or
more thereof.
29. A process according to claim 25 wherein said support is
alumina.
30. A process according to claim 25 wherein said hydrogen is
present in said highly unsaturated hydrocarbon.
31. A process according to claim 25 wherein said hydrogen is fed
separately and mixed with said highly unsaturated hydrocarbon prior
to said contacting with said composition.
32. A process according to claim 25 wherein said selectivity
enhancer is bismuth.
33. A process according to claim 25 wherein the selectivity
enhancer is gallium.
34. A process according to claim 25 wherein the selectivity
enhancer is lead.
35. A process according to claim 25 wherein said highly unsaturated
hydrocarbon comprises a fluid selected from the group consisting of
water, steam, water containing a soluble or insoluble substance,
and combinations of any two or more thereof.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a composition and a process useful
for catalytically hydrogenating an unsaturated hydrocarbon
compound.
BACKGROUND OF THE INVENTION
[0002] It is well known to one skilled in the art that an
unsaturated hydrocarbon compound can be produced by a thermal
cracking process. For example, a fluid stream containing a
saturated hydrocarbon such as, for example, ethane, propane,
butane, pentane, naphtha, or combinations of any two or more
thereof can be fed into a thermal (or pyrolytic) cracking furnace.
Within the furnace, the saturated hydrocarbon is converted to an
unsaturated hydrocarbon compound such as, for example, ethylene and
propylene. Unsaturated hydrocarbons are an important class of
chemicals that find a variety of industrial uses. For example,
ethylene can be used as a monomer or comonomer for producing a
polyolefin. Other uses of unsaturated hydrocarbons are well known
to one skilled in the art.
[0003] However, an unsaturated hydrocarbon produced by a thermal
cracking process generally contains an appreciable amount of highly
unsaturated hydrocarbons such as the less desirable alkyne(s),
diolefin(s), polyene(s), or combinations of two or more thereof.
For example, ethylene produced by thermal cracking of ethane is
generally contaminated with some acetylene which must be
selectively hydrogenated to ethylene, but not to ethane, in a
hydrogenation reaction. Similarly, propylene produced by thermal
cracking of a saturated hydrocarbon is generally contaminated with
propyne and propadiene which must be selectively hydrogenated to
propylene, but not propane. In a thermal cracking process for
producing a butene, butynes and butadienes are generally
co-produced which must be selectively hydrogenated to a butene, but
not a butane.
[0004] The so-called pygas which is a fluid stream containing
hydrocarbons having 5 or more carbon atoms per molecule comprises
debutanized aromatic concentrate (hereinafter referred to as DAC).
Pygas or DAC therefore comprises a large variety of, for example,
pentynes, pentadiene, pentatrienes, hexynes, hexadienes,
hexatrienes, aromatic compounds such as, for example, benzene,
toluene, xylenes, styrene, and ethylbenzene. In other words, pygas
or DAC comprises a mixture of highly unsaturated C.sub.5+
hydrocarbons, i.e., hydrocarbons containing 5 or more carbon atoms
per molecule. Generally, the trienes are hydrogenated to dienes
(diolefins) which in turn are selectively hydrogenated to
monoolefins, but not to alkanes. For an aromatic compound, such as
styrene which is hydrogenated to ethylbenzene, the aromatic ring is
not affected by the selective hydrogenation.
[0005] In all cases, the highly unsaturated hydrocarbons described
above are undesirable because they are high reactive and tend to
polymerize thereby forming gums if they are left in the product
stream which is used for gasoline or for further processing. As
such, they must be removed. A preferred process for removing the
highly unsaturated hydrocarbons is a selective hydrogenation which
is defined hereinbelow.
[0006] The selective hydrogenation of a highly unsaturated
hydrocarbon is generally, commercially carried out in the presence
of an alumina-supported palladium catalyst. In the case of the
selective hydrogenation of acetylene to ethylene, a
palladium-containing catalyst supported on an alumina in which
palladium is optionally distributed on the skin of the aluminum
support can be employed. See for example U.S. Pat. Nos. 4,404,124
and 4,484,015, disclosures of which are herein incorporated by
reference. The operating temperature for this hydrogenation process
is selected such that essentially all highly unsaturated
hydrocarbon, such as, for example, acetylene is hydrogenated to its
corresponding alkene such as, for example, ethylene thereby
removing the alkyne from the product stream while only an
insignificant amount of alkene is hydrogenated to alkane. Such a
selective hydrogenation process can minimize the losses of desired
unsaturated hydrocarbons and, in the front-end and total cracked
gas processes, avoids a "runaway" reaction which is difficult to
control, as has been pointed out in the above-identified
patents.
[0007] It is generally known to those skilled in the art that
impurities such as carbon monoxide, H.sub.2S, COS, mercaptans,
organic sulfides, thiophenes, or derivatives thereof which are
present in a product stream such as, for example, pygas can poison
and deactivate a palladium-containing catalyst. For example, carbon
monoxide is well known to temporarily poison and deactivate such a
hydrogenation catalyst. There is therefore an ever-increasing need
to develop a catalyst which is suitable for selective hydrogenation
of a highly unsaturated hydrocarbon such as, for example, a
diolefin in a pygas, especially in the presence of an impurity, to
a monoolefin.
[0008] Palladium supported on alumina has been successfully used in
dry hydrogenation processes for many years. However, in some
processes such as the so-called "total cracked gas" process in
which the steam is not removed from the olefins stream, the
selective hydrogenation of an alkyne to alkene must be accomplished
in the presence of steam. In such processes, the alumina supported
catalyst may have a much shorter life because alumina is not stable
in steam. Therefore, there is also an increasing need to develop a
palladium catalyst on a steam-stable support.
[0009] As such, development of an improved palladium catalyst and a
process therewith in the selective hydrogenation of a highly
unsaturated hydrocarbon such as a diolefin to a monoolefin in the
presence of an impurity would be a significant contribution to the
art and to the economy.
SUMMARY OF THE INVENTION
[0010] It is an object of this invention to provide a composition
that can be used for selectively hydrogenating a highly unsaturated
hydrocarbon such as a diolefin to a monoolefin. It is another
object of this invention to provide a palladium-containing catalyst
composition having incorporated therein a selectivity enhancer. It
is also an object of this invention to provide a process for
selectively hydrogenating a diolefin to its corresponding
monoolefin. It is a further object of this invention to carry out a
selective hydrogenation of a highly unsaturated hydrocarbon in a
pygas to a monoolefin. Other objects and advantages will become
more apparent as this invention is more fully described
hereinbelow.
[0011] According to a first embodiment of this invention, a
composition which can be used for selectively hydrogenating a
highly unsaturated hydrocarbon such as, for example, a diolefin, is
provided. The composition comprises palladium, at least one
selectivity enhancer, and an inorganic support. The composition can
also comprise silver.
[0012] According to a second embodiment of this invention, a
process which can be used for selectively hydrogenating a highly
unsaturated hydrocarbon to a less unsaturated hydrocarbon is
provided. The process comprises contacting a highly unsaturated
hydrocarbon with hydrogen, in the presence of a catalyst
composition, under a condition sufficient to effect a selective
hydrogenation of the highly unsaturated hydrocarbon. The catalyst
composition can be the same as the composition disclosed in the
first embodiment of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013] As used in the present invention, the term "fluid" denotes
gas, liquid, or combination thereof. The term "saturated
hydrocarbon" is referred to as any hydrocarbon which can be
converted to an unsaturated hydrocarbon such as an olefinic
compound by a thermal cracking process. An "unsaturated
hydrocarbon" as used in this application is a hydrocarbon having at
least one double bond between carbon atoms in the molecule.
Generally, examples of saturated hydrocarbons include, but are not
limited to, ethane, propane, butanes, pentanes, hexanes, octanes,
decanes, naphtha, and combinations of any two or more thereof.
Examples of unsaturated hydrocarbons include, but are not limited
to, monoolefins such as ethylene, propylene, butenes, pentenes,
cyclopentene, hexenes, cyclohexene, octenes, and decenes; aromatic
compounds such as naphthalene; alkynes such as acetylene, propyne,
and butynes; diolefins such as propadiene, butadienes, pentadienes
(including isoprene), hexadienes, octadienes, decadiene,
cyclobutadiene, cyclopentadiene, cyclohexadiene, cyclooctadiene,
and cyclodecadiene; and combinations of two or more thereof. The
term "highly unsaturated hydrocarbon" refers to a hydrocarbon which
contains a triple bond or two or more double bonds in a molecule.
The term "less unsaturated hydrocarbon" refer to a hydrocarbon in
which the triple bond in the highly unsaturated hydrocarbon is
hydrogenated to a double bond or to a hydrocarbon in which the
number of double bonds is at least one less than that in the highly
unsaturated hydrocarbon, preferably the less highly unsaturated
hydrocarbon is a monoolefin. The term "selective hydrogenation" is
referred to as a hydrogenation process which converts a highly
unsaturated hydrocarbon such as an alkyne, a diolefin, or a triene,
to a less unsaturated hydrocarbon such as a monoolefin without
hydrogenating the less unsaturated hydrocarbon to a saturated or a
more saturated hydrocarbon such as alkane. Generally, an aromatic
ring remains unchanged in a selective hydrogenation. For example,
styrene is hydrogenated to ethylbenzene.
[0014] According to the first embodiment of this invention, a
composition which can be used to selectively hydrogenate a highly
unsaturated hydrocarbon to a less unsaturated hydrocarbon is
provided. The composition can comprise, consist essentially of, or
consists of palladium, a selectivity enhancer, and an inorganic
support wherein the selectivity enhancer is selected from the group
consisting of lead, bismuth, thorium, iridium, tin, antimony,
gallium, germanium, arsenic, cadmium, mercury, and combinations of
any two or more thereof, the inorganic support can be an inorganic
oxide, and a spinel, or combinations of two or more thereof; and
the inorganic oxide can be a clay, an alumina, a silica, or
combinations of any two or more thereof. If a spinel support is
used, the metal of the spinel is selected from the group consisting
of zinc, magnesium, iron, manganese, any metal that can form a
spinel structure, such as Zr, Mo, Ru, Rh, Co, Ge, Ca, and
combinations of any two or more thereof. The palladium can be
distributed throughout the support or present on the skin of the
composition and the selectivity enhancer also can be distributed on
the skin of or throughout the composition. The composition can also
comprise silver. The presently preferred inorganic oxide is an
alumina. The presently preferred spinel is zinc aluminate, zinc
titanate, magnesium aluminate, or combinations of any two or more
thereof. These spinels are readily available and effective. The
term "skin" is referred to as the surface of the composition. The
"skin" can be any thickness as long as such thickness can promote
the selective hydrogenation disclosed herein. Generally, the
thickness of the skin can be in the range of from about 1 to about
1000, preferably about 5 to about 750, more preferably about 5 to
about 500, and most preferably 10 to 300 .mu.m. Presently, it is
preferred that palladium and a selectivity enhancer are supported
on an inorganic oxide support.
[0015] Generally, palladium can be present in the composition in
any weight percent (%) so long as the weight % is effective to
selectively hydrogenate an alkyne to an alkene, or a diolefin to a
monoolefin. The weight % of palladium can be in the range of from
about 0.0001 to about 5, preferably about 0.0005 to about 3, and
most preferably 0.001 to 1.5%. Similarly, the selectivity enhancer
can be present in the composition in any weight % as long as the
weight % can improve the selectivity of a selective hydrogenation
of an alkyne to an alkene, or a diolefin to a monoolefin as
compared to the use of a catalyst containing palladium and an
inorganic support. Generally, a selectivity enhancer can be present
in the composition in the range of from about 0.0003 to about 20,
preferably about 0.001 to about 10, and most preferably 0.003 to 5
weight %. Silver, if present, can be in the same weight % as the
selectivity enhancer.
[0016] Optionally, the composition can also comprise, consist
essentially of, or consist of palladium, a selectivity enhancer, an
alkali metal or alkali metal-containing compound, and an inorganic
support disclosed above. The alkali metal or alkali
metal-containing compound can be present in the composition in any
weight % that can effect the selective hydrogenation of a highly
unsaturated hydrocarbon to a less unsaturated hydrocarbon, and in
the range of from about 0.0001 to about 10, preferably about 0.001
to about 5, and most preferably about 0.005 to about 3 weight %.
The presently preferred alkali metal compound is an alkali metal
fluoride such as, for example, potassium fluoride.
[0017] Generally, the inorganic support can make up the rest of the
composition.
[0018] The composition can be in any physical form and dimension so
long as the physical form and dimension can be used as a catalyst
for selectively hydrogenating an alkyne to an alkene, or a diolefin
to a monoolefin. Generally, it is preferred the physical form be
spherical or cylindrical for such form is easy to handle. The
composition can generally have a size in the range of from about
0.1 to about 20, preferably about 0.5 to about 15, and most
preferably 1 to 10 mm in diameter. The composition can have a
surface area of from about 0.1 to about 150, preferably about 0.5
to about 50 m.sup.2/g, as determined by the well-known BET method
employing nitrogen.
[0019] According to the invention, any inorganic oxide can be used
as a support for the composition so long as the inorganic oxide can
effect the selective hydrogenation of a highly unsaturated
hydrocarbon to a less unsaturated hydrocarbon. Examples of suitable
inorganic oxide include, but are not limited to, an alumina, a
silica, a clay, or combinations thereof.
[0020] Generally, any spinel can be used as the support in the
composition so long as the composition can effect the selective
hydrogenation of an alkyne to an alkene, or a diolefin to a
monoolefin. As disclosed above, the metal of the spinel can include
magnesium, zinc, iron, manganese, any metal that can form a spinel,
and combinations of any two or more thereof. Examples of suitable
spinels include, but are not limited to, zinc aluminate, magnesium
aluminate, zinc titanate, calcium aluminate, manganese aluminate,
ferrous aluminate, calcium titanate, magnesium titanate, and
combinations of any two or more thereof.
[0021] The composition can be prepared by any suitable techniques.
Generally, the palladium can be placed on an inorganic support in
any suitable manner that will yield a composition meeting the
above-described parameters. The presently preferred technique
involves impregnating an inorganic support with an aqueous solution
of a suitable palladium compound. Generally, the extent of
penetration of the palladium can be controlled by adjustment of the
acidity of the solution with an acid such as, for example,
hydrochloric acid.
[0022] Examples of suitable palladium compounds include, but are
not limited to, palladium chloride, palladium bromide, palladium
iodide, palladium acetate, palladium nitrate, palladium sulfate,
palladium sulfide, palladium acetylacetonate, and combinations of
any two or more thereof. The presently preferred palladium compound
is palladium chloride for it is readily available.
[0023] One can use any suitable method to determine whether the
composition particles have the palladium concentrated in an area
within certain distance of the exterior surface. One technique
currently favored is the electron microprobe which is well known to
one skilled in the art. Another technique involves breaking open a
representative sample of calcined catalyst pills and treating them
with a dilute alcoholic solution of
N,N-dimethyl-para-nitrosoaniline. The treating solution reacts with
the oxidized palladium to give a red color which can be used to
evaluate the distribution of the palladium. Still another technique
involves breaking open a representative sample of calcined catalyst
pills followed by treatment with a reducing agent such as, for
example, hydrogen to change the color of the skin.
[0024] The selectivity enhancer can be distributed on the skin of
or throughout the composition in any suitable and effective manner
such as the process disclosed above for incorporating palladium
into or impregnating palladium onto a support. Examples of suitable
selectivity enhancer compounds include, but are not limited to,
lead chloride, lead bromide, lead iodide, lead acetate, lead
nitrate, lead sulfate, lead fluoride, lead perchloride, bismuth
chloride, bismuth bromide, bismuth iodide, bismuth acetate, bismuth
nitrate, bismuth sulfate, bismuth fluoride, bismuth perchloride,
gallium chloride, gallium bromide, gallium iodide, gallium acetate,
gallium nitrate, gallium sulfate, gallium fluoride, gallium
perchloride, thorium chloride, thorium bromide, thorium iodide,
thorium acetate, thorium nitrate, thorium sulfate, thorium
fluoride, thorium perchloride, iridium chloride, iridium bromide,
iridium iodide, iridium acetate, iridium nitrate, iridium sulfate,
iridium fluoride, iridium perchloride, tin chloride, tin bromide,
tin iodide, tin acetate, tin nitrate, tin sulfate, tin fluoride,
tin perchloride, antimony chloride, antimony bromide, antimony
iodide, antimony acetate, antimony nitrate, antimony sulfate,
antimony fluoride, antimony perchloride, germanium chloride,
germanium bromide, germanium iodide, germanium acetate, germanium
nitrate, germanium sulfate, germanium fluoride, germanium
perchloride, arsenic chloride, arsenic bromide, arsenic iodide,
arsenic acetate, arsenic nitrate, arsenic sulfate, arsenic
fluoride, arsenic perchloride, cadmium chloride, cadmium bromide,
cadmium iodide, cadmium acetate, cadmium nitrate, cadmium sulfate,
cadmium fluoride, cadmium perchloride, mercury chloride, mercury
bromide, mercury iodide, mercury acetate, mercury nitrate, mercury
sulfate, mercury fluoride, mercury perchloride, and combinations of
any two or more thereof. It is currently preferred to employ an
aqueous nitrate solution of one of these compounds in a quantity
greater than that necessary to fill the pore volume of the support.
Generally, the weight ratio of selectivity enhancer compound to
palladium compound can be such that the weight ratio of selectivity
enhancer to palladium is in the range of from about 0.1:1 to about
20:1, and preferably about 1:1 to about 10:1.
[0025] Silver can also be used as an additional selectivity
enhancer. Examples of suitable silver compounds include, but are
not limited to, silver chloride, silver bromide, silver iodide,
silver acetate, silver nitrate, silver sulfate, silver fluoride,
silver perchloride, and combinations of any two or more thereof.
The weight ratio of silver compound to palladium compound can be
the same as that disclosed above for selectivity enhancer compound
to palladium compound.
[0026] Thereafter, the impregnated composition can be dried at a
temperature in the range of about 25.degree. C. to about
150.degree. C., preferably about 25.degree. C. to 120.degree. C.,
and most preferably 30.degree. C. to 120.degree. C., followed by
calcining at a temperature of from about 200.degree. C. to about
1,200.degree. C., preferably about 275.degree. C. to about
850.degree. C., and most preferably 400.degree. C. to 700.degree.
C. for about 1 to about 40 hours, preferably about 1 to about 30
hours, and most preferably 2 to 25 hours.
[0027] Any alkali metal or alkali metal-containing compounds can be
used in the composition, with or without silver presence, if the
resulting composition can effect a selective hydrogenation of a
highly unsaturated hydrocarbon to a less unsaturated hydrocarbon.
Examples of suitable alkali metal compounds include sodium
fluoride, potassium fluoride, lithium fluoride, rubidium fluoride,
cesium fluoride, sodium iodide, potassium iodide, lithium iodide,
rubidium iodide, cesium iodide, sodium chloride, potassium
chloride, lithium chloride, rubidium chloride, cesium chloride,
sodium bromide, potassium bromide, lithium bromide, rubidium
bromide, cesium bromide, sodium hydroxide, potassium hydroxide,
lithium hydroxide, rubidium hydroxide, cesium hydroxide, sodium
oxide, potassium oxide, lithium oxide, rubidium oxide, cesium
oxide, sodium carbonate, potassium carbonate, lithium carbonate,
rubidium carbonate, cesium carbonate, sodium nitrate, potassium
nitrate, lithium nitrate, rubidium nitrate, cesium nitrate, and
combinations of any two or more thereof. The presently preferred
alkali metal-containing compound is potassium fluoride for it is
effective in the selective hydrogenation. The alkali
metal-containing compound can be incorporated into a support by any
methods known to one skilled in the art. For example, an alkali
metal-containing compound can be impregnated or sprayed onto a
support before the support is impregnated with a suitable palladium
compound, and preferably also with a suitable selectivity enhancer
compound. Alternatively, the alkali metal-containing compound can
be incorporated, for example, by impregnation or spraying onto the
composition simultaneously with or after the impregnation with a
suitable palladium compound. The alkali metal-containing compound
can also be incorporated into a support between the palladium and
selectivity enhancer impregnation steps or after the impregnation
with palladium and selectivity enhancer compounds. Alternatively,
one can also apply a "wet reducing" step which is a treatment with
dissolved reducing agents such as hydrazine, alkali metal
borohydrides, aldehydes such as formaldehyde, carboxylic acids such
as formic acid or ascorbic acid, reducing sugars such as
dextrose.
[0028] In the second embodiment of this invention, a process for
selectively hydrogenating a highly unsaturated hydrocarbon such as,
for example, an alkyne or a diolefin, to a less unsaturated
hydrocarbon such as, for example, a monoolefin is provided. The
process can comprise, consist essentially of, or consist of
contacting a fluid feed comprising a highly unsaturated hydrocarbon
with hydrogen, in the presence of a catalyst under a condition
sufficient to effect the selective hydrogenation of an alkyne to an
alkene, or a diolefin to a monoolefin. Though any highly
unsaturated hydrocarbon can be used in the process, it is presently
preferred that an alkyne, a diolefin, or a triene containing 2 to
about 15, preferably 2 to about 12, and most preferably 2 to 10
carbon atoms be used.
[0029] The catalyst composition can be the same composition
described above in the first embodiment of this invention. Hydrogen
can be present either in the fluid feed stream containing the
highly unsaturated hydrocarbon or in a hydrogen-containing fluid
which is mixed with the fluid feed stream before contacting with
the catalyst composition. If a hydrogen-containing fluid is used,
it can be a substantially pure hydrogen or any fluid containing
sufficient concentration of hydrogen to effect the hydrogenation.
It can also contain other gases such as, for example, nitrogen,
methane, carbon monoxide, carbon dioxide, steam, or combinations of
any two or more thereof so long as the hydrogen-containing fluid
contains sufficient concentration of hydrogen to effect the
hydrogenation.
[0030] Optionally, the catalyst can be first treated, prior to the
selective hydrogenation, with a reducing agent, such as a
hydrogen-containing fluid, to activate the catalyst. Such
reductive, or activation, treatment can be carried out at a
temperature in the range of about 20.degree. C. to about
300.degree. C., preferably about 25.degree. C. to about 250.degree.
C., and most preferably 30.degree. C. to 200.degree. C. for a time
period of about 1 minute to about 30 hours, preferably about 0.5 to
about 25 hours, and most preferably 1 to 20 hours. During this
reductive treatment, the oxidation state of palladium and
selectivity enhancer compounds can be substantially reduced, for
example, to palladium metal and selectivity enhancer metal.
However, alkali metal compounds generally are not reduced by this
treatment. When this optional reductive treatment is not carried
out, the hydrogen gas present in the reaction medium accomplishes
this reduction of oxides of palladium and selectivity enhancer
during the initial phase of the selective hydrogenation reaction of
this invention.
[0031] The selective hydrogenation process of this invention can be
carried out by contacting a fluid which comprises a highly
unsaturated hydrocarbon, in the presence of hydrogen, with the
catalyst composition disclosed above. The fluid comprising a highly
unsaturated hydrocarbon can further comprise a fluid which can be
water, steam, water containing a soluble or insoluble substance, or
combinations of any two or more thereof. Preferably the fluid
containing a highly unsaturated hydrocarbon is a pygas stream
containing an alkyne, a diolefin, a triene, or combinations of two
or more thereof or is an unsaturated alkene stream containing an
alkyne, a diolefin, a triene, or combinations of two or more
thereof as an impurity, generally at a level of about 1 mg/Kg (ppm)
to about 50,000 ppm of the fluid. The highly unsaturated
hydrocarbon can be, for example, an alkyne, a diolefin, or triene,
or combinations of any two or more thereof. Examples of suitable
alkynes include, but are not limited to, acetylene, propyne,
1-butyne, 2-butyne, 1-pentyne, 2-pentyne, 3-methyl-1-butyne,
1-hexyne, 1-heptyne, 1-octyne, 1-nonyne, 1-decyne, and combinations
of any two or more thereof. These alkynes are primarily
hydrogenated to the corresponding alkenes. For example, acetylene
is primarily hydrogenated to ethylene, propyne is primarily
hydrogenated to propylene, the butynes are primarily hydrogenated
to the corresponding butenes (1-butene, 2-butenes), and pentynes
are primarily hydrogenated to pentenes. Examples of suitable
diolefins include, but are not limited to, propadiene, butadienes,
isoprene, pentadienes, cyclopentadienes, hexadienes,
cyclohexadienes, heptadienes, octadienes, cyclooctadienes,
nonodienes, decadienes, methylcyclopentadienes, cycloheptadienes,
methylcyclohexadienes, dimethylcyclopentadienes,
ethylcyclopentadienes, methylheptadienes, dimethylhexadienes,
ethylhexadienes, trimethylpentadienes, methyloctadienes,
dimethylheptadienes, ethylheptadienes, trimethylheptadienes, and
combinations of any two or more thereof. These diolefins are
selectively hydrogenated to their corresponding monoolefins.
Examples of suitable trienes include, but are not limited to,
pentatrienes, cyclopentatrienes, hexatrienes, cyclohexatrienes,
heptatrienes, octatrienes, cyclooctatrienes, nonotrienes,
decatrienes, methylcyclopentatrienes, cycloheptatrienes,
methylcyclohexatrienes, dimethylcyclopentatrienes,
ethylcyclopentatrienes, methylheptatrienes, dimethylhexatrienes,
ethylhexatrienes, trimethylpentatrienes, methyloctatrienes,
dimethylheptatrienes, ethylheptatrienes, trimethylheptatrienes, and
combinations of any two or more thereof. In order to best attain
substantially complete selective hydrogenation of a highly
unsaturated hydrocarbon, there should be at least about one mole of
hydrogen for each mole of the alkyne or diolefin present and two
moles of hydrogen for each mole of the triene present in the fluid
feed stream. A fluid containing a highly unsaturated hydrocarbon
and hydrogen can be introduced into a reactor. Alternatively, a
fluid containing a highly unsaturated hydrocarbon and a
hydrogen-containing fluid can be introduced into a reactor
separately, contemporaneously introduced, or premixed before their
introduction to a reactor to contact with the catalyst which is
generally laced in the reactor before introduction of the fluid(s)
into the reactor. Any reactors known to one skilled in the art for
selective hydrogenation can be employed in the present invention.
The process of the invention can be carried out in a batch,
semi-batch, or continuous mode.
[0032] The term "impurity" used herein denotes any component in a
fluid stream that is not a major component. Examples of impurities
other than an alkyne or a diolefin include, but are not limited to
carbon monoxide, hydrogen sulfide, carbonyl sulfide (COS),
mercaptans (RSH), organic sulfides (RSR), organic disulfides
(RSSR), thiophenes, thiophanes, methane, ethane, propane, butane,
carbon dioxide, water, alcohols, ethers, aldehydes, ketones,
carboxylic acids, esters, other oxygenated compounds, and
combinations of two or more thereof, wherein each R can be an alkyl
or cycloalkyl or aryl group containing 1 to about 15, preferably 1
to 10 carbon atoms. Generally, each impurity is present in the
fluid stream in trace amounts. For example, an impurity can be
present at a level of less than about 1 weight percent (%).
[0033] The temperature necessary for the selective hydrogenation of
a highly unsaturated hydrocarbon such as, for example, an alkyne,
to a less unsaturated hydrocarbon such as, for example, an alkene
is any temperature that can effect the conversion of, for example,
an alkyne to an alkene. It generally depends largely upon the
activity and selectivity of a catalyst, the amounts of impurities
in the fluid, and the desired extent of removal of impurities.
Generally, a reaction temperature can be in the range of about
10.degree. C. to about 300.degree. C., preferably about 20 to about
250.degree. C., and most preferably 30 to 200.degree. C. Any
suitable reaction pressure can be employed. Generally, the total
pressure is in the range of about 50 to about 1,500, preferably
about 75 to about 1,200, and most preferably 100 to 1,000 pounds
per square inch gauge (psig). The liquid or gas hourly space
velocity of the fluid feed can also vary over a wide range.
Typically, the gas space velocity can be in the range of about 10
to about 20,000 m.sup.3 of the fluid per m.sup.3 of catalyst per
hour, more preferably about 50 to about 12,500
m.sup.3/m.sup.3/hour, and most preferably 100 to 8,000
m.sup.3/m.sup.3/hour. The liquid space velocity of the feed can be
in the range of from about 0.001 to about 200, preferably about
0.01 to about 100, and most preferably 0.1 to 50
m.sup.3/m.sup.3/hour. The molar ratio of hydrogen to a highly
unsaturated hydrocarbon is in the range of about 0.5:1 to about
10,000:1, preferably about 1:1 to about 5,000:1 and most preferably
1:1 to 1,000:1. The hourly space velocity of the
hydrogen-containing fluid, if separately fed to a reactor
containing a selective hydrogenation catalyst, is chosen so as to
provide a molar ratio of H.sub.2 to a highly unsaturated
hydrocarbon in the range of about 0.5:1 to about 10,000:1,
preferably about 1:1 to about 5,000:1 and most preferably 1:1 to
1,000:1.
[0034] Regeneration of the catalyst composition can be accomplished
by heating the catalyst composition in air (at a temperature which
preferably does not exceed about 700.degree. C.) so as to burn off
any impurities such as, for example, organic matter and/or char
that may have accumulated on the catalyst composition. Optionally,
the oxidatively regenerated composition is reduced with H.sub.2 or
a suitable hydrocarbon (as has been described above) before its
redeployment in the selective hydrogenation of this invention.
[0035] The following examples are presented to further illustrate
this invention and are not to be construed as unduly limiting the
scope of the invention.
EXAMPLE I
[0036] This comparative example illustrates a selective
hydrogenation using a commercially available catalyst. More
specifically this example involved the selective hydrogenation of a
(high diolefin) pygas stream (C.sub.5+ co-product stream) from an
olefin plant. The primary goal was the selective hydrogenation of
C.sub.5 diolefins to C.sub.5 monoolefins (without making the
C.sub.5 alkane). The secondary goal was the conversion of styrene
to ethylbenzene.
[0037] The catalyst used was Calsicat E-144SDU which was obtained
from Mallinckrodt Chemical Inc., Calsicat, Erie, Pa. It was 0.5% Pd
on {fraction (1/16)} inch alumina spheres which had about 40
m.sup.2/g surface area. The liquid feed used in the runs was
obtained from Phillips Petroleum Company's olefin plants. The
composition of this liquid feed was about 72 weight % BTX (about 55
weight % benzene, 15 weight % toluene, 2 weight % xylenes) with
about 6 to 8 weight % styrene and 2 weight % ethylbenzene, also
with about 0.1 weight % total C.sub.5 alkanes (including
cyclopentane), 3 weight % total C.sub.5 monoolefins (including
cyclopentene), 4 weight % total C.sub.5 diolefins (including
cyclopentadiene), and about 3 weight % dicyclopentadiene, the
remaining about 8 to 10 weight % was made up of many small
components, mainly C.sub.6-C.sub.10 olefins and diolefins.
[0038] A portion (20.0 cc or about 17.5 g) of catalyst was loaded
into a 1/2 inch inner diameter stainless steel reactor equipped
with a 1/8 inch center thermocouple well. The reactor was mounted
in a tube furnace. While the reactor was purging with pure hydrogen
gas, it was warmed to 100.degree. F., and pressured up to 350 psig
with H.sub.2 gas. The catalyst was pretreated for 1 hour, at
100.degree. F., with 100 cc/min H.sub.2 flowing. The H.sub.2 flow
rate was controlled by a Brooks mass flow controller.
[0039] The hydrogen flow rate was then dropped to about 60 cc/min,
and the liquid feed pump (Waters Associates, Inc. Model 6000A
Solvent Delivery System) started at a rate of 1.0 cc/min where it
was maintained throughout the run. The catalyst performance was
mapped out as a function of styrene conversion. The catalyst bed
hot spot temperature was maintained at about 200-205.degree. F.
throughout the run (by adding, or more often, since the reaction
was highly exothermic, removing heat as necessary). The conversion
was controlled by varying the H.sub.2 rate in the range of about 40
to 140 cc/min as shown in Table I. The reactor was allowed to line
out, or stabilize, at a given set of conditions for at least 1.5
hours before the liquid product from the reactor was sampled. The
liquid product was analyzed by GC-FID using a standard boiling
point type capillary column.
[0040] The catalysts selectivity was measured by the ability to
single-step hydrogenate aliphatic (noncyclic) C.sub.5 diolefins to
aliphatic C.sub.5 monoolefins (without further hydrogenating the
monoolefins to aliphatic C.sub.5 paraffins). First, the feed was
analyzed by GC, which individually identified and quantified all
the C.sub.5 hydrocarbons. Then, the maximum theoretical aliphatic
C.sub.5 olefins for the feed was approximated as the total weight %
of all aliphatic C.sub.5 mono-olefins in the feed
(3-methylbutene-1, 1-pentene, 2-methylbutene-1, trans-pentene-2,
cis-pentene-2, and 2-methylbutene-2) plus the total weight % of all
aliphatic C.sub.5 diolefins in the feed (1,4-pentadiene, isoprene,
and 1,3-pentadiene). Secondly, the total weight % of all aliphatic
C.sub.5 monoolefins was found for each product sample (i.e., the
sum of the 3-methylbutene- 1, 1-pentene, 2-methylbutene-1,
trans-pentene-2, cis-pentene-2, and 2-methylbutene-2 peaks). Then
the Percent of Theoretical C.sub.5 Olefin Make (PTOM) was
calculated as: 1 PTOM = total weight % of all aliphatic C 5 mono -
olefins ( for the product ) .times. 100 maximum theoretical
aliphatic C 5 olefins ( for the feed )
[0041] The results are shown in Table I which shows the GC results
and PTOM, as a function of styrene conversion, for the catalyst of
Example I. As can be seen, the conversion was controlled by
variation of the hydrogen rate.
1TABLE I.sup.a Total Total Total Sample H.sub.2 Temp C.sub.5
C.sub.5 C.sub.5 Styrene Number cc/min (.degree. F.) Paraffins
Olefins Diolefins cyC.sub.5 cyC.sub.5.dbd. cyC.sub.5.dbd..dbd.
Conv. PTOM 1 (feed) 0.04 1.58 2.65 0.03 1.24 1.18 0.00 37.3 2 60
206 1.83 2.39 0.58 0.69 0.80 0.25 46.00 56.5 3 70 211 1.89 2.65
0.40 0.78 0.75 0.17 57.70 62.6 4 80 202 2.61 2.23 0.13 1.08 0.50
0.06 80.70 52.7 5 90 208 3.39 1.68 0.00 1.42 0.21 0.00 96.50 39.6 6
(feed) 0.03 1.62 2.72 0.03 1.28 1.21 0.00 37.2 7 90 206 3.29 1.58
0.05 1.36 0.23 0.02 94.80 36.4 8 85 202 3.16 1.85 0.00 1.39 0.24
0.00 96.00 42.6 9 80 203 2.96 1.99 0.05 1.31 0.29 0.02 87.40 45.9
10 75 207 2.61 2.25 0.09 1.18 0.41 0.04 87.30 51.8 11 70 211 2.37
2.48 0.14 1.10 0.48 0.06 83.30 57.2 12 65 205 4.26 0.70 0.00 1.60
0.01 0.00 99.70 16.1 .sup.aTotal C.sub.5 denotes aliphatic
C.sub.5's; cyC.sub.5 denotes cyclopentane; cyC.sub.5.dbd. denotes
cyclopentene; cyC.sub.5.dbd..dbd. denotes cyclopentadiene; Temp
denotes the temperature of the catalyst bed hot spot; the values
for total C.sub.5 paraffins, total C.sub.5 olefins, # total C.sub.5
diolefins, CyC.sub.5, OcyC.sub.5.dbd., and CyC.sub.5.dbd..dbd. are
weight %; and the values for styrene conversion are percent of
styrene converted to ethylbenzene.
[0042] Using the data from Table I, the PTOM was plotted versus the
styrene conversion. The PTOM at 95% styrene conversion was then
read off the plot and the plot showed that the control catalyst
gave about 43% PTOM at 95% styrene conversion.
EXAMPLE II
[0043] This example illustrates a selective hydrogenation using a
Pd/alumina catalyst having incorporated thereon 0.5% lead.
[0044] Calsicat E-144SDU Pd/alumina catalyst (22.0 g) was added to
a 250 ml beaker. A lead nitrate (Pb(NO.sub.3).sub.2) solution
prepared by dissolving 0.178 g lead nitrate with 9.3 g of bottled
H.sub.2O. The Pd/alumina was impregnated with the lead nitrate
solution by incipient wetness method followed by drying overnight
(16 hours) at 85.degree. C. The resulting material was calcined in
a programmable furnace for 2 hours at 110.degree. C., 2 hours at
200.degree. C., and then 4 hours at 400.degree. C. with 200 cc/min
dry air. Thereafter, the calcined catalyst was cooled to about
25.degree. C. The selective hydrogenation using this catalyst was
conducted using the same procedure described in Example I. The
results are shown in Table II.
2TABLE II.sup.a Total Total Total Sample H.sub.2 Temp C.sub.5
C.sub.5 C.sub.5 Styrene Number cc/min (.degree. F.) Paraffins
Olefins Diolefins cyC.sub.5 cyC.sub.5.dbd. cyC.sub.5.dbd..dbd.
Conv. PTOM 1 (feed) 0.03 1.55 2.62 0.03 1.23 1.13 0.00 37.3 2 60
234 2.09 2.57 0.15 0.82 0.66 0.06 66.95 61.5 3 70 201 1.95 2.80
0.03 1.00 0.49 0.01 90.80 67.0 4 80 208 2.47 2.22 0.00 1.28 0.18
0.00 99.30 53.1 5 90 206 3.04 1.71 0.00 1.45 0.06 0.00 99.80 41.0 6
(feed) 0.03 1.52 2.57 0.02 1.21 1.11 0.00 37.2 7 90 206 2.18 2.03
0.00 1.23 0.13 0.00 99.90 49.7 8 85 201 2.09 2.34 0.00 1.23 0.19
0.00 99.40 57.2 9 80 201 2.17 2.39 0.00 1.25 0.18 0.00 99.70 58.6
10 75 207 1.97 2.64 0.00 1.23 0.23 0.00 100.00 64.6 11 70 206 1.55
2.78 0.00 1.01 0.36 0.00 99.60 68.1 12 65 203 1.31 3.29 0.00 0.85
0.59 0.00 95.70 80.5 13 60 204 1.10 3.67 0.00 0.72 0.76 0.00 87.70
89.7 .sup.aSee Table I.
[0045] Table II shows that lead is an effective selectivity
enhancer because a Pd/Pb/alumina catalyst gave a PTOM at 95%
styrene conversion of 82%, when the data in Table II were plotted
as described in Example I. This is better than the 43% for the
Pd-only catalyst with this same feed shown in Table I.
EXAMPLE III
[0046] This example shows a selective hydrogenation of a
pentadiene-rich stream using a 0.5% Pb/0.5% K (as KF) on Pd/alumina
catalyst. First, 22.0 g of Calsicat E-144SDU Pd/alumina was placed
in a 250 ml beaker. Thereafter a Pb/K solution containing 0.178 g
of lead nitrate (Pb(NO.sub.3).sub.2), 0.163 g KF, and 9.3 g of
bottled H.sub.2O was added by incipiently wetting the Pd/alumina
with the Pb/K solution, dropwise, while stirring. The
Pb/K-impregnated Pd/alumina was then dried overnight at 85.degree.
C. The dried material was calcined as described in Example II. The
catalyst was used in a selective hydrogenation also as described in
Example II and the results are shown in Table III.
3TABLE III.sup.a Total Total Total Sample H.sub.2 Temp C.sub.5
C.sub.5 C.sub.5 Styrene Number cc/min (.degree. F.) Paraffins
Olefins Diolefins cyC.sub.5 cyC.sub.5.dbd. cyC.sub.5.dbd..dbd.
Conv. PTOM 1 (feed) 0.03 1.48 2.51 0.02 1.18 1.08 0.00 37.1 2 60
170 1.60 2.59 0.48 0.58 0.81 0.20 41.20 64.9 3 70 200 1.46 2.81
0.26 0.60 0.79 0.11 50.90 70.4 4 80 204 2.64 2.12 0.00 1.15 0.33
0.00 96.70 53.3 5 90 194 2.19 2.35 0.00 1.11 0.33 0.00 97.40 59.1 6
(feed) 0.03 1.46 2.47 0.03 1.17 1.07 0.00 37.1 7 90 207 2.29 2.10
0.00 1.18 0.23 0.00 98.70 53.6 8 85 206 2.15 2.43 0.00 1.15 0.28
0.00 98.70 62.0 9 80 212 2.10 2.48 0.00 1.15 0.27 0.00 99.10 63.1
10 75 206 1.99 2.79 0.00 1.16 0.33 0.00 99.20 71.0 11 70 204 1.66
3.06 0.00 1.06 0.42 0.00 99.70 77.9 12 65 203 1.34 3.42 0.00 0.85
0.62 0.00 96.40 87.1 13 60 205 1.13 3.69 0.00 0.70 0.77 0.00 88.40
93.9 .sup.aSee Table I.
[0047] The results show that Pb can be effectively co-promoted with
KF. This catalyst gave 89% maximum theoretical C.sub.5 olefin make
(PTOM) at 95% styrene conversion when the data from Table III were
plotted as described in Example I.
EXAMPLE IV
[0048] This example shows a selective hydrogenation using a 1.5%
bismuth on 0.5% Pd/alumina catalyst. The catalyst was prepared by
first weighing 22.0 g of Calsicat E-144SDU into a 250 ml beaker.
The Pd/alumina was impregnated with a solution containing 0.382 g
of bismuth nitrate (pentahydrate) and 9.5 g distilled H.sub.2O and
then dried 4 hours at 85.degree. C. The catalyst was then
impregnated a second time with another 0.382 g of BiNO.sub.3
dissolved with 9.5 g of H.sub.2O. Thereafter the resulting
Bi/Pd/alumina was dried, calcined, and then used as a catalyst in a
selective hydrogenation process. The results are shown in Table
IV.
4TABLE IV.sup.a Total Total Total Sample H.sub.2 Temp C.sub.5
C.sub.5 C.sub.5 Styrene Number cc/min (.degree. F.) Paraffins
Olefins Diolefins cyC.sub.5 cyC.sub.5.dbd. cyC.sub.5.dbd..dbd.
Conv. PTOM 1 (feed) 0.04 1.85 30.03 0.03 1.43 1.14 0.00 37.8 2 60
206 2.53 2.86 0.12 0.90 0.65 0.04 80.90 58.7 3 70 205 2.49 3.08
0.01 1.10 0.46 t.sup.b 95.90 63.1 4 80 204 3.72 2.25 0.00 1.54 0.10
0.00 99.80 46.1 5 90 216 3.53 1.96 0.00 1.49 0.07 0.00 100.00 40.2
6 (feed) 0.03 1.68 2.82 0.03 1.36 1.08 0.00 37.4 7 90 202 3.10 2.38
0.00 1.46 0.11 0.00 99.90 52.9 8 85 203 3.16 2.46 0.00 1.49 0.11
0.00 100.00 54.6 9 80 206 3.36 2.60 0.00 1.56 0.09 0.00 100.00 57.8
10 75 205 2.76 2.80 0.00 1.42 0.15 0.00 100.00 62.3 11 70 207 2.24
2.31 0.00 1.24 0.32 0.00 99.80 51.4 12 65 203 1.87 3.75 0.00 1.07
0.51 0.00 98.00 83.2 13 (feed) 0.04 1.74 2.85 0.03 1.37 1.08 0.00
37.9 14 70 210 2.65 2.96 0.00 1.39 0.20 0000 99.30 64.5 15 65 204
1.89 3.70 0.00 1.08 0.49 0.00 99.10 80.7 16 60 203 1.41 3.99 0.04
0.86 0.68 0.01 94.20 87.0 17 55 205 1.27 4.22 0.12 0.76 0.80 0.04
85.80 92.1 .sup.aSee Table I. .sup.bt denotes trace amount
detected.
[0049] Table IV shows that this Bi/Pd/alumina catalyst gave about
87% maximum theoretical aliphatic C.sub.5 olefin make at 95%
styrene conversion when the data in Table IV were plotted as
described in Example I.
EXAMPLE V
[0050] This examples illustrates a selective hydrogenation using a
gallium-promoted catalyst. First, 22.0 g of Calsicat E-144SDU,
described in Example I, was placed in a 250 ml beaker and was
impregnated with a solution containing 1.65 g of Ga(NO.sub.3).sub.3
and 9.5 g of bottled H.sub.2O by the process described in Example
II. The gallium-promoted Pd/alumina was then dried at 90.degree. C.
overnight followed by air calcining as described in Example II to
prepare a catalyst containing about 2 weight % gallium and 0.5
weight % palladium on alumina. The catalyst was used in a selective
hydrogenation as described in Example I. The results are shown in
Table V.
5TABLE V.sup.a Total Total Total Sample H.sub.2 Temp C.sub.5
C.sub.5 C.sub.5 Styrene Number cc/min (.degree. F.) Paraffins
Olefins Diolefins cyC.sub.5 cyC.sub.5.dbd. cyC.sub.5.dbd..dbd.
Conv. PTOM 1 (feed) 0.04 1.77 2.82 0.03 1.38 1.05 0.00 38.6 2 60
204 2.36 2.29 0.27 0.87 0.56 0.10 70.10 50.0 3 70 208 2.39 2.86
0.03 1.18 0.33 0.01 93.80 62.3 4 80 204 3.26 2.12 0.00 1.40 0.13
0.00 99.00 46.3 5 90 206 3.90 1.16 0.00 1.45 0.02 0.00 99.80 25.3 6
(feed) 0.04 1.70 2.71 0.03 1.34 1.01 0.00 38.6 7 90 225 4.27 0.97
0.00 1.50 0.02 t.sup.b 99.40 21.9 8 85 206 3.82 1.56 0.00 1.52 0.01
0.00 100.00 35.3 9 80 207 3.41 1.80 0.00 146 0.04 0.00 100.00 40.9
10 75 201 2.59 2.61 0.00 1.37 0.13 0.00 100.00 59.2 11 70 211 2.35
3.11 0.00 1.27 0.28 0.00 98.10 70.5 12 65 206 1.80 3.29 0.03 1.07
0.39 0.01 93.20 74.5 13 60 210 1.54 3.64 0.06 0.96 0.54 0.02 88.20
82.6 .sup.aSee Table I. .sup.bSee Table IV.
[0051] Table V shows that this catalyst gave 74% maximum
theoretical aliphatic olefin (C.sub.5) make at 95% styrene
conversion when the data were plotted as described in Example
I.
EXAMPLE VI
[0052] This example shows a selective hydrogenation of a
pentadiene-rich stream using a Pd/alumina catalyst having
impregnated thereon lead and silver. The catalyst was prepared by
placing 22.0 g of a 0.5% Pd/1.5% Ag/alumina, which was prepared
according to the method disclosed in U.S. Pat. No. 5,489,565
disclosure of which is incorporated herein by reference, into a 250
ml beaker. Thereafter, the Pd/Ag/alumina catalyst was impregnated
with a solution containing 0.178 g of lead nitrate
(Pb(NO.sub.3).sub.2) dissolved with 9.0 g of bottled H.sub.2O by
incipient wetness method. The lead nitrated-impregnated Pd/alumina
was dried overnight at 85.degree. C. The dried material was then
calcined in a programmable furnace for 2 hours at 110.degree. C., 2
hours at 200.degree. C. and then 4 hours at 400.degree. C. with 200
cc/min dry air. The catalyst was then used in a selective
hydrogenation process as described in Example I. The results are
shown in Table VI.
6TABLE VI.sup.a Total Total Total Sample H.sub.2 Temp C.sub.5
C.sub.5 C.sub.5 Styrene Number cc/min (.degree. F.) Paraffins
Olefins Diolefins cyC.sub.5 cyC.sub.5.dbd. cyC.sub.5.dbd..dbd.
Conv. PTOM 1 (feed) 0.03 1.55 2.62 0.03 1.24 1.14 0.00 37.2 2 60
173 1.43 2.82 0.37 0.60 0.84 0.16 47.10 67.5 3 70 203 1.21 3.10
0.24 0.56 0.87 0.10 57.50 74.3 4 80 205 1.19 3.29 0.12 0.63 0.84
0.04 75.95 78.9 5 90 198 1.22 3.21 0.10 0.68 0.80 0.04 79.20 77.0 6
100 199 1.11 3.15 0.10 0.65 0.79 0.04 78.40 75.6 7 (feed) 0.03 1.58
2.66 0.03 1.26 1.15 0.00 37.3 8 90 225 1.26 3.20 0.05 0.81 0.67
0.01 89.60 75.4 9 85 199 0.85 3.37 0.09 0.58 0.84 0.03 78.20 79.5
10 80 207 1.02 3.42 0.05 0.69 0.76 0.01 86.90 80.6 11 75 211 1.08
3.80 0.04 0.71 0.84 0.01 88.00 89.6 12 70 208 0.92 3.46 0.04 0.63
0.79 0.01 86.60 81.5 13 70 230 1.05 37.3 0.03 0.71 0.80 0.01 89.90
87.8 14 65 230 1.01 3.75 0.03 0.68 0.81 0.01 90.10 88.4 15 (feed)
0.03 1.50 2.52 0.03 1.21 1.10 0.00 37.3 16 65 241 0.96 3.64 0.04
0.69 0.78 0.01 91.80 90.5 17 60 233 0.94 3.91 0.00 0.67 0.85 0.00
96.50 97.3 18 55 216 0.70 4.04 0.03 0.47 1.02 0.01 91.60 100.4 19
55 225 0.71 4.12 0.03 0.48 1.03 0.01 91.50 102.5 20 50 230 0.55
4.22 0.09 0.37 1.12 0.02 80.60 105.1 .sup.aSee Table I.
[0053] When the data shown in Table VI were plotted as described in
Example I, the plot showed that this catalyst gave 98% maximal
theoretical aliphatic C.sub.5 olefin make (PTOM) at 95% styrene
conversion. This 98% PTOM is much better than the 43% for a
commercial catalyst shown in Example I.
[0054] The results shown in the above tables also clearly
demonstrate that the catalysts of this invention are highly
effective for the complete removal of both aliphatic and cyclic
diolefins from the feed because little or no diolefins were
observed in the reactor effluent.
[0055] The selectivity (or the PTOM), as shown above, was a
function of conversion. That is, for a given catalyst, the PTOM
(selectivity) would vary depending on the severity of the reaction
conditions (temperature, pressure, hydrogen rate, etc.). Therefore,
for the direct comparison of one catalyst to a second catalyst to
be meaningful, they must be compared under conditions of constant
conversion. The constant conversion condition was chosen to be the
point of 95% conversion of styrene to ethylbenzene. Therefore, the
measure of selectivity reported for each catalyst was the PTOM at
95% styrene conversion. The PTOM's at 95% styrene conversion
described in Tables I-VI are summarized below in Table VII.
7 TABLE VII Catalyst PTOM.sup.a control (0.5% Pd/Al.sub.2O.sub.3)
43 (I) 0.5% Pb/0.5% Pd/Al.sub.2O.sub.3 82 (II) 0.5% Pb/0.5% KF/0.5%
Pd/Al.sub.2O.sub.3 89 (III) 1.5% Bi/0.5% Pd/Al.sub.2O.sub.3 87 (IV)
2% Ga/0.5%/Al.sub.2O.sub.3 74 (V) 0.5% Pb/1.5% Ag/0.5%
Pd/Al.sub.2O.sub.3 98 (VI) .sup.aThe Roman numeral in the
parenthesis corresponds to Example numeral.
[0056] Table VII clearly demonstrates that the selectivity
enhancers of the invention significantly increased the
effectiveness of the catalysts containing the selectivity enhancers
as compared to the control catalyst. Table VII also demonstrates
that silver, a commonly used selectivity enhancer, can be combined
with the selectivity enhancers of the present invention to further
increase the effectiveness of the catalysts containing the
selectivity enhancers as compared to the control catalyst. Table
VII further demonstrates the effectiveness of an alkali metal
halide on improving the selectivity of a selective dehydrogenation
catalyst having incorporated therein a selectivity enhancer of the
present invention.
[0057] The results shown in the above examples also clearly
demonstrate that the present invention is well adapted to carry out
the objects and attain the ends and advantages mentioned as well as
those inherent therein. While modifications may be made by those
skilled in the art, such modifications are encompassed within the
spirit of the present invention as defined by the specification and
the claims.
* * * * *