U.S. patent application number 12/725520 was filed with the patent office on 2010-11-04 for apparatus for ionic liquid catalyst regeneration.
This patent application is currently assigned to Chevron U.S.A., Inc.. Invention is credited to Moinuddin Ahmed, Bong-Kyu Chang, Huping Luo, Krishniah Parimi.
Application Number | 20100278699 12/725520 |
Document ID | / |
Family ID | 40799214 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100278699 |
Kind Code |
A1 |
Luo; Huping ; et
al. |
November 4, 2010 |
Apparatus for ionic liquid catalyst regeneration
Abstract
An apparatus for regenerating an ionic liquid catalyst
comprising a reactive extraction column, the reactive extraction
column comprising: (a) an upper feed port, wherein a slurry of an
ionic liquid catalyst and an aluminum metal enter the reactive
extraction column; (b) a lower feed port, wherein a solvent and
optionally a hydrogen gas enter the reactive extraction column; (c)
a moveable bed comprised of the aluminum metal between the upper
and lower feed ports, wherein the ionic liquid catalyst and the
aluminum metal reacts to free conjunct polymers from the ionic
liquid catalyst and some of the freed conjunct polymers are
extracted from the ionic liquid catalyst by the solvent to provide
regenerated ionic liquid catalyst; (d) a lower exit port, wherein
the regenerated ionic liquid catalyst exits the reactive extraction
column; and (e) an upper exit port, wherein the solvent and freed
conjunct polymers exit the reactive extraction column.
Inventors: |
Luo; Huping; (Richmond,
CA) ; Ahmed; Moinuddin; (Hercules, CA) ;
Parimi; Krishniah; (Alamo, CA) ; Chang; Bong-Kyu;
(Novato, CA) |
Correspondence
Address: |
CHEVRON CORPORATION
P.O. BOX 6006
SAN RAMON
CA
94583-0806
US
|
Assignee: |
Chevron U.S.A., Inc.
|
Family ID: |
40799214 |
Appl. No.: |
12/725520 |
Filed: |
March 17, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12003577 |
Dec 28, 2007 |
|
|
|
12725520 |
|
|
|
|
Current U.S.
Class: |
422/140 |
Current CPC
Class: |
B01J 8/0453 20130101;
B01J 2219/30215 20130101; B01J 2231/4205 20130101; B01J 8/22
20130101; B01J 31/0284 20130101; B01J 2219/30223 20130101; B01J
31/40 20130101; B01J 2219/30203 20130101; B01J 31/0298 20130101;
B01J 38/56 20130101; B01J 8/0492 20130101 |
Class at
Publication: |
422/140 |
International
Class: |
B01J 8/18 20060101
B01J008/18 |
Claims
1. An apparatus for regenerating an ionic liquid catalyst which has
been deactivated by conjunct polymers comprising a reactive
extraction column, the reactive extraction column comprising: (a)
an upper feed port in the upper end of the reactive extraction
column, wherein a slurry of an ionic liquid catalyst and an
aluminum metal enter the reactive extraction column; (b) a lower
feed port in the lower end of the reactive extraction column,
wherein a solvent and optionally a hydrogen gas enter the reactive
extraction column; (c) a moveable bed comprised of the aluminum
metal between the upper and lower feed ports, wherein the ionic
liquid catalyst and the aluminum metal reacts to free conjunct
polymers from the ionic liquid catalyst and some of the freed
conjunct polymers are extracted from the ionic liquid catalyst by
the solvent to provide regenerated ionic liquid catalyst; (d) a
lower exit port in the lower end of the reactive extraction column,
wherein the regenerated ionic liquid catalyst exits the reactive
extraction column; and (e) an upper exit port in the upper end of
the reactive extraction column, wherein the solvent and freed
conjunct polymers exit the reactive extraction column.
2. The apparatus according to claim 1, wherein the reactive
extraction column further comprises: (f) a lower extraction packing
and an upper extraction packing, wherein the moveable bed is
sandwiched between the lower and upper extraction packings; and (g)
a screen between the moveable bed and the lower extraction packing
to trap stray aluminum metal that has left the moveable bed,
wherein a portion of the ionic liquid catalyst and the aluminum
metal reacts in the lower and upper extraction packings to free
conjunct polymers from the portion of the ionic liquid catalyst and
some of freed conjunct polymers are extracted from the ionic liquid
catalyst by the solvent in the lower and upper extraction packings
to provide regenerated ionic liquid catalyst.
3. The apparatus according to claim 1, further comprising: a first
filter connected to the lower exit port, wherein a portion of the
aluminum metal is separated from the regenerated ionic liquid
catalyst. a second filter connected to the upper exit port, wherein
a second portion of the aluminum metal is separated from the
solvent and conjunct polymers; and a coalescer downstream from the
second filter, wherein a portion of the regenerated ionic liquid
catalyst that is blended with the solvent and the conjunct polymers
is separated from the solvent and the conjunct polymers; and
wherein the reactive extraction column further comprises a recycle
inlet port in the upper end of reactive extraction column, wherein
the regenerated ionic liquid catalyst that exits the coalescer is
recycled to the reactive extraction column.
4. The apparatus according to claim 1, wherein the reactive
extraction column further comprises: (f) a settling zone
immediately below the upper feed port, wherein the slurry of the
ionic liquid catalyst and the aluminum metal settles after entering
the reactive extraction column through the upper feed port; (g) a
first feed distributor below the settling zone, wherein the first
feed distributor uniformly distributes the slurry of the ionic
liquid catalyst and the aluminum metal from the settling zone into
the moveable bed; and (h) a second feed distributor adjacent to the
lower feed port in the bottom end of the reactive extraction
column, wherein the second feed distributor uniformly distributes
the solvent from the lower feed port into the moveable bed.
5. The apparatus according to claim 1, wherein the moveable bed is
sandwiched between a pair of extraction packings.
6. The apparatus according to claim 5, wherein at least one of the
pair of extraction packings provide an additional reaction zone and
increase the chance of the aluminum metal reacting to
extinction.
7. The apparatus according to claim 5, wherein the pair of
extraction packings provide an additional extraction zone for
solvent extracting the freed conjunct polymer from an ionic liquid
catalyst/conjunct polymer phase.
8. The apparatus according to claim 3, wherein the coalescer is a
reverse-emulsifier.
9. The apparatus according to claim 1, further comprising a screen
that traps stray aluminum metal that has migrated through
gravitational effects.
10. The apparatus according to claim 4, wherein the first feed
distributor is located above the moveable bed.
11. The apparatus according to claim 4, wherein the second feed
distributor is located below the moveable bed.
12. The apparatus according to claim 1, wherein the hydrogen gas is
supplied from an outside source.
13. The apparatus according to claim 1, wherein the hydrogen gas is
supplied from a separate on-site facility.
14. The apparatus according to claim 14, wherein the separate
on-site facility reforms natural gas into hydrogen using steam
reforming processes.
15. The apparatus according to claim 1, wherein the solvent is a
non-branched hydrocarbon solvent.
16. The apparatus according to claim 1, additionally comprising a
coalescer downstream from the upper exit port that separates the
ionic liquid catalyst from the solvent and freed conjunct polymers
that exit the reactive extraction column, and wherein a separated
ionic liquid catalyst is recycled to the reactive extraction
column.
17. The apparatus according to claim 1, wherein the ionic liquid
catalyst is a pyridinium or imidazolium-based chloroaluminate ionic
liquid.
18. The apparatus according to claim 1, wherein the ionic liquid
catalyst has been used to catalyze a Friedel-Crafts reaction.
19. The apparatus according to claim 19, wherein the Friedel-Crafts
reaction is alkylation.
20. An apparatus for regenerating an ionic liquid catalyst
comprising a reactive extraction column, the reactive extraction
column comprising: (a) an upper feed port, wherein a slurry of an
ionic liquid catalyst and an aluminum metal enter the reactive
extraction column; (b) a lower feed port, wherein a solvent and
optionally a hydrogen gas enter the reactive extraction column; (c)
a moveable bed comprised of the aluminum metal between the upper
and lower feed ports, wherein the ionic liquid catalyst and the
aluminum metal reacts to free conjunct polymers from the ionic
liquid catalyst and some of the freed conjunct polymers are
extracted from the ionic liquid catalyst by the solvent to provide
regenerated ionic liquid catalyst; (d) a lower exit port, wherein
the regenerated ionic liquid catalyst exits the reactive extraction
column; and (e) an upper exit port, wherein the solvent and freed
conjunct polymers exit the reactive extraction column.
Description
RELATED APPLICATIONS
[0001] This application is a Divisional of U.S. application Ser.
No. 12/003,577, filed Dec. 28, 2007, published as US20090170687A1,
and fully incorporated herein.
FIELD OF ART
[0002] The system and apparatus as described herein relate to
regeneration of liquid catalysts. More particularly, the system and
apparatus as described herein relate to regeneration of ionic
liquid catalysts.
BACKGROUND
[0003] Ionic liquids are liquids that are composed entirely of ions
as a combination of cations and anions. The most common ionic
liquids are those prepared from organic-based cations and inorganic
or organic anions. The most common organic cations are ammonium
cations, but phosphonium and sulphonium cations are also frequently
used. Pyridinium-based and imidazolium-based cations are perhaps
the most commonly used cations. Anions include, but are not limited
to, BF.sub.4--, PF.sub.6--, haloaluminates such as
Al.sub.2Cl.sub.7-- and Al.sub.2Br.sub.7--,
[(CF.sub.3SO.sub.2).sub.2N]--, alkyl sulphates (RSO.sub.3--),
carboxylates (RCO.sub.2--) and many others. The most catalytically
interesting ionic liquids are those derived from ammonium halides
and Lewis acids (such as AlCl.sub.3, TiCl.sub.4, SnCl.sub.4,
FeCl.sub.3 . . . etc.). Ionic liquids may be suitable, for example,
for use as a catalyst and as a solvent in alkylation.
[0004] One class of ionic liquids are the so-called "low
temperature" ionic liquids, which are generally organic salts with
melting points under 100.degree. C. and often even lower than room
temperature. Another class of ionic liquids is fused salt
compositions, which are molten at low temperature and are useful as
catalysts, solvents, and electrolytes. Such compositions are
mixtures of components which are liquid at temperatures below the
individual melting points of the components.
[0005] Chloroaluminate ionic liquids are perhaps the most commonly
used ionic liquid catalyst systems. They are classified as low
temperature ionic liquids or fused salt compositions. Alkyl
imidazolium or pyridinium salts, for example, can be mixed with
aluminum trichloride (AlCl.sub.3) to form fused chloroaluminate
salts. The use of fused salts of 1-alkylpyridinium chloride and
aluminum trichloride as electrolytes is discussed in U.S. Pat. No.
4,122,245, which is incorporated by reference in its entirety
herein. Other patents which discuss the use of fused salts of
aluminum trichloride and alkylimidazolium halides as electrolytes
are U.S. Pat. Nos. 4,463,071 and 4,463,072, which documents are
incorporated by reference in their entirety herein.
[0006] U.S. Pat. No. 5,104,840, which is incorporated by reference
in its entirety herein, describes ionic liquids which comprise at
least one alkylaluminum dihalide and at least one quaternary
ammonium halide and/or at least one quaternary ammonium phosphonium
halide; and their uses as solvents in catalytic reactions.
[0007] U.S. Pat. No. 6,096,680, which is incorporated by reference
in its entirety herein, describes liquid clathrate compositions
useful as reusable aluminum catalysts in Friedel-Crafts reactions.
In one embodiment, the liquid clathrate composition is formed from
constituents comprising (i) at least one aluminum trihalide, (ii)
at least one salt selected from alkali metal halide, alkaline earth
metal halide, alkali metal pseudohalide, quaternary ammonium salt,
quaternary phosphonium salt, or ternary sulfonium salt, or a
mixture of any two or more of the foregoing, and (iii) at least one
aromatic hydrocarbon compound.
[0008] Aluminum-containing catalysts are among the most common
Lewis acid catalysts employed in Friedel-Craft reactions.
Friedel-Craft reactions are reactions which fall within the broader
category of electrophylic substitution reactions and include
alkylations.
[0009] Other examples of ionic liquids and their methods of
preparation are found in U.S. Pat. Nos. 5,731,101 and 6,797,853 and
in U.S. Patent Application Publication Nos. 2004/0077914 and
2004/0133056. All of these documents are incorporated by reference
in their entireties herein.
[0010] As a result of use, ionic liquid catalysts can become
deactivated, i.e. lose activity, and may eventually need to be
replaced. Alkylation processes utilizing an ionic liquid catalyst
form by-products known as conjunct polymers. These conjunct
polymers deactivate the ionic liquid catalyst by forming complexes
with the ionic liquid catalyst. Conjunct polymers are highly
unsaturated molecules and can complex the Lewis acid portion of the
ionic liquid catalyst via their double bonds. For example, as
aluminum trichloride in aluminum trichloride-containing ionic
liquid catalysts becomes complexed with conjunct polymers, the
activity of these ionic liquid catalysts becomes impaired or at
least compromised. Conjunct polymers may also become chlorinated
and through their chloro groups may interact with aluminum
trichloride in aluminum-trichloride containing catalysts and
therefore reduce the overall activity of these catalysts or lessen
their effectiveness as catalysts for their intended purpose.
[0011] Deactivation of ionic liquid catalyst by conjunct polymers
is not only problematic for alkylation chemistry, but also effects
the economic feasibility of using ionic liquid catalyst as they are
expensive to replace. Therefore, commercial exploitation of ionic
liquid catalysts in alkylation is impossible unless they can be
efficiently regenerated and recycled.
[0012] Only a few methods for removing conjunct polymers from
acidic ionic liquid catalysts in order to regenerate the catalysts
have been devised. These methods are described in U.S. Patent
Application Publication No. 2007/0142213, which document is
incorporated in its entirety herein, and include, for example,
hydrogenation, addition of a basic reagent, and alkylation.
[0013] Hydrogenation saturates the double bonds of the conjunct
polymers such that they release the acidic ionic liquid catalysts.
For hydrogenation to occur, hydrogen must either be fed to the
acidic ionic liquid catalyst/conjunct polymer complexes or hydrogen
must be produced in situ. This may be done by treating the catalyst
containing the conjunct polymers with a metal in the presence of a
Broensted acid where interaction between the metal and the acid
produces the needed hydrogen. For example, reacting aluminum metal
with hydrochloric acid will produce hydrogen and aluminum
trichloride. Treating the spent catalyst containing conjunct
polymers with Al metal in the presence of enough HCl will produce
the hydrogen needed to saturate the double bonds of the conjunct
polymers. After hydrogenation, the hydrogenated conjunct polymers
are removed by solvent extraction or decantation and the
regenerated ionic liquid catalyst is recovered.
[0014] Addition of a basic agent (e.g., amines or ammonium
chloride) similarly breaks up the acidic ionic liquid
catalyst/conjunct polymer complexes as the basic agent forms new
complexes with the catalyst. The basic agent must be carefully
chosen so that it is part of the catalyst system undergoing
regeneration. Otherwise, the basic agent will simply deactivate the
catalyst in the same manner as the conjunct polymers. Additionally,
the basic agent will react not only with the acidic ionic liquid
catalyst/conjunct polymer complexes (e.g., AlCl.sub.3/conjunct
polymer complexes) but also with any unbound cation (e.g.,
AlCl.sub.3). Therefore, the basic agent must correspond to the
basic parent species of cation from which the ionic liquid to be
regenerated was originally produced and the basic agent must be
added in an amount sufficient to react with both cations bound in
the acidic ionic liquid/conjunct polymer complexes and unbound
cations. Then the free conjunct polymers are removed and the
remaining new complexes are contacted with additional unbound
cations (e.g., AlCl.sub.3) to fully regenerate the catalyst. As an
example, a used chloroaluminate ionic liquid may be contacted with
butylpyridinium chloride to provide butylpyridinium
tetrachloroaluminate and free the conjunct polymers and then the
butylpyridinium tetrachloroaluminate may be contacted with
AlCl.sub.3 to fully restore the catalyst's activity.
[0015] However, while effective, each of these methods suffers from
certain shortcomings. Thus, to take advantage of the potential of
ionic liquids as catalysts, particularly in alkylation reactions,
the industry continues to search for an effective and efficient
ionic liquid catalyst regeneration process.
SUMMARY
[0016] Disclosed herein is a system for regenerating an ionic
liquid catalyst which has been deactivated by conjunct polymers
comprising: feeding a slurry of aluminum metal and the ionic liquid
catalyst into the top of a moveable bed comprised of aluminum metal
within a reactor, wherein at least a portion of the ionic liquid
catalyst is bound to conjunct polymers; feeding a solvent and
optionally hydrogen gas into the bottom of the reactor to move
upwards through the reactor and into the moveable bed; reacting the
aluminum metal with the ionic liquid catalyst in the presence or
the absence of the hydrogen gas in the moveable bed to free the
conjunct polymers from the ionic liquid catalyst; and extracting
the conjunct polymers from the ionic liquid catalyst with the
solvent to provide a regenerated ionic liquid catalyst. The system
can be used in a method for regenerating ionic liquid catalyst
which has been deactivated by conjunct polymers.
[0017] Also disclosed herein is an apparatus for regenerating an
ionic liquid catalyst which has been deactivated by conjunct
polymers comprising a reactive extraction column. The reactive
extraction column comprises: (a) an upper feed port in the upper
end of the reactive extraction column, wherein a slurry of ionic
liquid catalyst and aluminum metal enter the reactive extraction
column; (b) a lower feed port in the lower end of the reactive
extraction column, wherein a solvent and, if so desired, hydrogen
gas enter the reactive extraction column; (c) a moveable bed
comprised of aluminum metal between the upper and lower feed ports,
wherein the ionic liquid catalyst and the aluminum metal reacts in
the presence or absence of hydrogen gas to free conjunct polymers
from the ionic liquid catalyst and some of the freed conjunct
polymers are extracted from the ionic liquid catalyst by the
solvent to provide regenerated ionic liquid catalyst; (d) a lower
exit port in the lower end of the reactive extraction column,
wherein the regenerated ionic liquid catalyst exits the reactive
extraction column; and (e) an upper exit port in the upper end of
the reactive extraction column, wherein the solvent and freed
conjunct polymers exit the reactive extraction column.
[0018] Among other factors, the system and apparatus disclosed
herein are based on the recent discovery of a novel process,
including reaction and extraction steps, to remove conjunct
polymers from the ionic liquid catalyst. The reaction step entails
contacting an ionic liquid catalyst with aluminum metal in the
presence or absence of hydrogen gas to dissociate the conjunct
polymers from the ionic liquid catalyst. It has been discovered
that this dissociation allows the conjunct polymers to be
thereafter successfully removed from the resulting conjunct
polymer-ionic liquid catalyst mixture by solvent extraction to
produce a regenerated ionic liquid catalyst that may be recycled to
any process in which the catalyst is utilized. However, it has been
realized that when the conjunct polymers remain in the vicinity of
the ionic liquid catalyst for any appreciable length of time, they
re-bond with and again deactivate the catalyst. Such
re-deactivation cannot be tolerated. Thus, the conjunct polymers
must be extracted as soon as they are freed from the ionic liquid
catalyst. The present system and apparatus provide an effective and
efficient means of conducting the novel process so that the freed
conjunct polymers do not have the opportunity to re-deactivate the
ionic liquid catalyst.
BRIEF DESCRIPTION OF THE FIGURE OF THE DRAWING
[0019] The FIGURE of the drawing is a schematic illustration of an
apparatus as disclosed herein for regenerating an ionic liquid
catalyst which has been deactivated by conjunct polymers.
DETAILED DESCRIPTION
Definitions
[0020] The term "conjunct polymer" as used herein refers to a
polymeric compound that might bond to a cationic species of the
ionic liquid catalyst by pi bonding or sigma bonding or other
means, which results in the polymeric compound binding to the
catalyst, so that it is not removable by simple hydrocarbon
extraction.
[0021] As used herein, the term "isoparaffin" means any
branched-chain saturated hydrocarbon compound, i.e., a
branched-chain alkane with a chemical formula of C.sub.nH.sub.2n+2.
Examples of isoparaffins are isobutane and isopentane.
[0022] The term "olefin" means any unsaturated hydrocarbon compound
having at least one carbon-to-carbon double bond, i.e. an alkene
with a chemical formula of C.sub.nH.sub.2n. Examples of olefins
include ethylene, propylene, butene, and so on.
[0023] The term "moveable bed," as used herein, refers to the
fluidic bed formed by the interaction of the ionic liquid catalyst,
the solvent, and aluminum metal within the reactor.
[0024] A specially designed system and apparatus for conducting a
process of regenerating or re-activating an ionic liquid catalyst,
which has been deactivated by conjunct polymers, are disclosed
herein. Basically, the catalyst regeneration process involves first
reacting spent ionic liquid catalyst with aluminum metal in the
presence or absence of hydrogen gas in order to free conjunct
polymers from the ionic liquid catalyst and then extracting the
freed conjunct polymers from the catalyst phase with a solvent.
Conjunct polymers form during a variety of reactions in which ionic
liquid catalysts are employed, for example, alkylation,
polymerization, dimerization, oligomerization, acetylation,
metatheses, and copolymerization. Conjunct polymers are also
by-products of many types of Friedel-Crafts reactions, which are
reactions that fall within the broader category of electrophylic
substitution, like alkylation and acylation. The system and
apparatus as described herein can be incorporated into an
alkylation process whereby isoparaffins (e.g., isobutane and/or
isopentane) and olefins (e.g., ethylene, propylene, and/or butene)
react to form low volatility, high quality gasoline blending
components.
[0025] The term conjunct polymer was first used by Pines and
Ipatieff to distinguish these polymeric molecules from the usual
polymers. Unlike typical polymers, conjunct polymers are
polyunsaturated cyclic, polycyclic and acyclic molecules formed by
concurrent acid-catalyzed reactions including, among others,
polymerization, alkylation, cyclization, and hydride transfer
reactions. Conjunct polymers consist of an unsaturated intricate
network of molecules that may include one or a combination of 4-,
5-, 6- and 7-membered rings and some aromatic entities in their
skeletons. Some examples of the likely polymeric species were
reported by Miron et al. (Journal of Chemical and Engineering Data,
1963) and Pines (Chem. Tech, 1982), which documents are
incorporated by reference in their entirety herein. These molecules
contain double and conjugated bonds in intricate structures
containing a combination of cyclic and acyclic skeletons.
[0026] In practice, conjunct polymers are also called "red oils"
due to their color and "acid-soluble oils" due to their high uptake
in the catalyst phase where saturated hydrocarbons and paraffinic
products are usually immiscible.
[0027] The conjunct polymers deactivate ionic liquid catalysts
because they form complexes with or simply interact with the ionic
liquid catalysts. It is believed that complexes form because
conjunct polymers, by virtue of their double bonds, form pi
complexes with the Lewis acid species in the ionic liquid catalyst.
As an example, conjunct polymers can complex with AlCl.sub.3, a
Lewis acid present in the ionic liquid catalyst 1-butyl-pyridinium
heptachloroaluminate. Complex formation can weaken the acid
strength of the catalyst, decrease catalyst activity, and
eventually render the catalyst ineffective for influencing
reactions such as an alkylation reaction between isoparaffins and
olefins. As a result, it is believed that catalyst activity is a
function of the concentration of conjunct polymers in the ionic
liquid phase whereby catalyst activity decreases as the
concentration of conjunct polymers increases.
[0028] The system and apparatus as described herein are especially
suited for conducting the catalyst regeneration process because
they perform the reaction step of freeing the conjunct polymers and
the extraction step of removing the conjunct polymers almost
simultaneously. It is advantageous, if not necessary, to react the
ionic liquid catalyst to free the conjunct polymers and
subsequently extract the freed conjunct polymers from the ionic
liquid catalyst within a very short period of time because the
freed conjunct polymers can re-bond to the ionic liquid catalyst if
left in the catalyst phase. Such re-bonding or re-complexing is
obviously undesirable and defeats the purpose of the catalyst
regeneration process. But if the conjunct polymers are immediately
removed from the catalyst phase, they cannot again deactivate the
ionic liquid catalyst. Since the system and apparatus as described
herein permit extraction the instant the conjunct polymers are
freed, the system and apparatus can have improved conjunct polymer
recovery rates.
[0029] The catalyst regeneration system and apparatus as disclosed
herein can be used to regenerate an ionic liquid catalyst used to
catalyze any one of various types of reactions including
Friedel-Crafts reactions. However, in one embodiment, the ionic
liquid catalyst is used to catalyze an alkylation reaction between
at least one isoparaffin and at least one olefin.
System
[0030] The present system comprises feeding a slurry of aluminum
metal and the ionic liquid catalyst into the top of a moveable bed
comprised of aluminum metal within a reactor while also feeding a
solvent and optionally hydrogen gas into the bottom of the reactor.
These feeds create a counter-current flow within the reactor. It is
important that at least a portion of the ionic liquid catalyst in
the system is bound to conjunct polymers, and, therefore, is
deactivated. The solvent and hydrogen, if fed, move upwards through
the reactor into the moveable bed, where they meet the slurry of
aluminum metal and ionic liquid catalyst. In the moveable bed of
the system, the aluminum metal reacts with the ionic liquid
catalyst in the presence or the absence of hydrogen gas to free
(i.e. de-bond) the conjunct polymers from the catalyst. Thereafter,
the system involves extracting the conjunct polymers from the ionic
liquid catalyst with the solvent, which results in a regenerated
ionic liquid catalyst.
[0031] In one embodiment of the system as described herein, the
moveable bed is sandwiched between a pair of extraction packings.
The extraction packings serve to trap any portion of catalyst and
aluminum metal that escapes from the area of the moveable bed. The
portion of the aluminum metal and catalyst that travels to the
lower extraction packing has the opportunity to further react in
the lower extraction packing. The portion of the aluminum metal and
that travels to the upper extraction packing has the opportunity to
further react in the upper extraction packing. Thus, the extraction
packings can provide an additional reaction zone and increase the
chance of the aluminum metal reacting to extinction thereby
reducing aluminum loss.
[0032] The step of extracting the conjunct polymers from the ionic
liquid catalyst can take place in only the moveable bed or in both
the moveable bed and the extraction packings. When the system does
not include extraction packings, all extraction occurs in the
moveable bed. However, when the system includes both the moveable
bed and the extraction packings, a portion of the extraction occurs
in the moveable bed and a portion of the extraction occurs in the
extraction packings. When the conjunct polymer recovery rate is
higher, the extraction step generally takes place in both the
moveable bed and extraction packings.
[0033] In the extraction packings, the freed conjunct polymers are
extracted by the solvent such that regenerated catalyst flows from
the extraction packings. The aluminum metal may remain in the
extraction packings for further reaction or, alternatively, may
exit the reactor.
[0034] The regeneration system can further include isolating the
regenerated ionic liquid catalyst and the solvent, respectively.
Once the regenerated ionic liquid catalyst is isolated, it may be
returned to the process for which it is needed, for example,
alkylation. Isolating the solvent allows for recycling the solvent
to the system so that it is not necessary to constantly feed new
solvent to the reactor. However, it should be appreciated that a
certain amount of fresh, make-up solvent may need to be provided to
the reactor in addition to the recycled solvent.
[0035] Isolation of the regenerated ionic liquid catalyst may be
accomplished by filtration. Filtering the regenerated ionic liquid
catalyst after extracting the conjunct polymers from it will remove
any aluminum metal present in the ionic liquid catalyst. Such
filtering prevents the aluminum metal from being carried away to
and fouling or otherwise affecting, due to the presence of solid
particles, downstream process units.
[0036] Likewise, filtration of the solvent can lead to isolation of
the solvent. Filtering the solvent and its dissolved conjunct
polymers after extracting the conjunct polymers from the ionic
liquid catalyst will remove any aluminum metal present in the
solvent-conjunct polymer phase. As stated above, filtering prevents
aluminum metal from being carried away to and fouling or otherwise
affecting, due to the presence of solid particles, downstream
process units.
[0037] It is also possible to isolate additional regenerated
catalyst from any residual solvent-conjunct polymer phase by
coalescing (i.e. reverse emulsifying) the solvent-conjunct polymer
phase. In the system as described herein, a portion of the ionic
liquid catalyst is inevitably blended with the solvent and its
dissolved conjunct polymers. This catalyst-solvent-conjunct polymer
mixture is generally in the form of an emulsion. Therefore,
coalescing the mixture separates the catalyst from the solvent and
conjunct polymers. This separated, regenerated catalyst, even if it
is only a small amount, can be returned to the process in which the
catalyst is used. Ionic liquid catalysts are generally quite
expensive, so this coalescing step is beneficial to the system as
described herein and any process in which the catalyst is
exploited.
[0038] As explained above, the regeneration system extracts the
freed conjunct polymers from the catalyst phase soon after they are
de-bonded from the ionic liquid catalyst so that they do not have
the opportunity to re-bond to the ionic liquid catalyst. Thus, it
is extremely beneficial if the step of extracting the conjunct
polymers from the ionic liquid catalyst with the solvent occurs
instantaneously after the step of reacting the aluminum metal with
the ionic liquid catalyst.
Apparatus
[0039] The present apparatus comprises a single process unit,
called a reactive extraction column, in which both the reaction and
extraction steps occur essentially simultaneously.
[0040] The reactive extraction column 10 is illustrated in the
FIGURE as a vertical column. It comprises (1) an upper feed port 2
in the upper end of the column; (2) a lower feed port 6 in the
lower end of the column; (3) a moveable bed 5 comprised of aluminum
metal between the upper and lower feed ports 2, 6; (4) a lower exit
port 11 in the lower end of the column; and (5) an upper exit port
12 in the upper end of the column. A slurry of ionic liquid
catalyst and aluminum metal 1 enter the column through the upper
feed port 2, while a solvent and optionally hydrogen gas enter the
column through the lower feed port 6. The feed ports and exit ports
of the column set up a counter-current flow within the column. The
slurry of ionic liquid catalyst and aluminum metal 1 migrates
downward through the column, while the solvent and optional
hydrogen gas migrate upward through the column. All four components
meet in the moveable bed 5 where the ionic liquid catalyst and the
aluminum metal react in the presence or absence of the hydrogen gas
to free conjunct polymers from the ionic liquid catalyst. The
moveable bed 5 also facilitates quick extraction of the freed
conjunct polymers from the ionic liquid catalyst into the solvent
as the solvent is present in the moveable bed 5. Such extraction
provides a regenerated ionic liquid catalyst. The regenerated ionic
liquid catalyst 18 then exits the column through the lower exit
port 11 and the solvent with its dissolved conjunct polymers 19
exit the column through the upper exit port 12.
[0041] The reactive extraction column may further comprise a pair
of extraction packings, referred to herein as an upper extraction
packing 8a and a lower extraction packing 8b. The extraction
packings can be commonly available packings, e.g., structural metal
packings or Rasching rings or Koch-Sulzer packings, etc. The
purpose of the packing is to increase surface area for reaction and
extraction, increase mixing, and enhance liquid-liquid mass
transfer. The upper and lower extraction packings 8a, 8b surround
the moveable bed such that the moveable bed is sandwiched between
them. The upper and lower extraction packings 8a, 8b further
facilitate the catalyst regeneration process. The extraction
packings serve two primary purposes.
[0042] First, the extraction packings provide a second reaction
zone for the ionic liquid catalyst and any aluminum metal carried
over to them from the moveable bed. Catalyst may escape the
moveable bed prior to reaction with the aluminum metal. If so, the
unreacted catalyst may be trapped by the extraction packings where
it can react with aluminum metal. Alternatively, aluminum metal may
escape the moveable bed. If so, this aluminum metal may be trapped
by the extraction packings where it can react with and be consumed
by deactivated catalyst.
[0043] Second, the extraction packings provide an additional
extraction zone for solvent extracting the freed conjunct polymer
from the ionic liquid catalyst/conjunct polymer phase. In a column
without extraction packings, a portion of regenerated ionic liquid
catalyst might escape from the moving bed prior to extraction
thereby allowing any freed conjunct polymer to re-bond with that
portion of regenerated ionic liquid catalyst. The extraction
packings prevent this problem by providing an area between the
moving bed and the upper and lower exit ports where the solvent has
an additional opportunity to remove the freed conjunct
polymers.
[0044] The reactive extraction column may further include a screen
13 between the movable bed 5 and the lower extraction packing 8b as
shown in the FIGURE. Since the reactive extraction column 10 is a
vertical column, the aluminum metal tends to eventually descend to
the lower end of the moveable bed. The screen 13 traps stray
aluminum metal that has migrated through gravitational effects
before it can fall into a pool of regenerated ionic liquid catalyst
9, which accumulates at the bottom of the column.
[0045] The apparatus may also further include filters 14a, 14b for
removing aluminum metal carried over from the column to the
regenerated ionic liquid catalyst 18 and the solvent-conjunct
polymer phase 19, respectively. A first filter 14a can be in fluid
communication with the lower exit port 11 such that the regenerated
ionic liquid catalyst 18 passes through the filter 14a. The filter
14a traps aluminum metal to provide an aluminum-free, regenerated
ionic liquid catalyst 20. A second filter 14b can be in fluid
communication with the upper exit port 12 such that the
solvent-conjunct polymer phase 19 passes through the filter 14b.
The filter 14b traps aluminum metal to provide an aluminum-free,
solvent-conjunct polymer phase 21. In a reactive extraction column
without extraction packings, the filters 14a, 14b are even more
important because there are no extraction packings to trap the
aluminum metal and prevent it from traveling to downstream process
units. Aluminum metal collected in the first and second filters
14a, 14b will eventually be fed into the column for
consumption.
[0046] Additionally, the apparatus can include a coalescer 15
downstream from the second filter 14b to remove ionic liquid
catalyst blended with the aluminum-free, solvent-conjunct polymer
phase 21. The coalescer 15 is a reverse-emulsifier, which separates
the catalyst from the solvent-conjunct polymer phase. The catalyst
16 is heavier that the solvent-conjunct polymer phase 17, so it
sinks to the bottom of the coalescer and can be drawn off and
returned to the column 10 through a recycle inlet port 22 in the
upper end of the column 10. In this manner, no expensive ionic
liquid catalyst is wasted and the solvent can be subsequently
isolated and re-used in the column.
[0047] In one embodiment of the apparatus as described herein, the
reactive extraction column can further comprise a settling zone 3,
a first feed distributor 4, and a second feed distributor 7. The
settling zone 3 is an area located immediately below the upper feed
port 2, where the slurry of ionic liquid catalyst and aluminum
metal 1 settles. The feed that enters the column through the upper
feed port is directed to the first feed distributor 4, which
uniformly distributes it downward through the column 10 and into
the moveable bed 5. Due to its function, the first feed distributor
4 is located below the settling zone 3 and above the moveable bed
5. While the first feed distributor 4 dispenses the slurry, its
counterpart, the second feed distributor 7 uniformly distributes
the solvent and hydrogen gas, if used, from the lower feed port 6
upwards through the column 10 and into the moveable bed 5. The
second feed distributor 7 is located adjacent to the lower feed
port 6 in the bottom end of the column 10 such that it is above the
ionic liquid catalyst pool 9 and below the moveable bed 5. Then, in
the moveable bed 5 and the upper and lower extraction packings 8a,
8b (if present), the ionic liquid catalyst, aluminum metal,
hydrogen gas, and solvent interact as described above.
Hydrogen
[0048] According to the present system and apparatus, hydrogen may
be supplied from any source. Hydrogen may be separately supplied
from an outside source. For example, hydrogen can be bought and
transported to the location where the regeneration process takes
place or hydrogen can be supplied from a separate on-site facility
that reforms natural gas into hydrogen using stream reforming
processes.
Solvent
[0049] Solvent extraction, which occurs in both the system and
apparatus as described herein, is a common method of extraction.
The solvent can be a low boiling point solvent so that it is easily
recovered. Hydrocarbon solvents function well as solvents in the
present system and apparatus. Exemplary hydrocarbon solvents are
pentane, hexane, heptane, octane, decane, n-butane, isobutane,
isopentane, and mixtures thereof. The solvent can be a non-branched
hydrocarbon solvent so that side reactions with the regenerated
catalyst are limited.
Aluminum Metal
[0050] The aluminum metal can be in the form of, for example,
powder (20-75 micrometer), pellets (1-3 mm) or aluminum beads (5-15
nm). Alternatively, the aluminum metal can be in the form of
granules, sponges, gauzes, wire, rods, etc. Any size and shape is
acceptable as long as sufficient external surface area is
available. The aluminum metal may be in (1) macroscopic form, which
includes wires, foils, fine particles, sponges, gauzes, granules,
etc. or (2) microscopic form, which includes powders, smokes,
colloidal suspensions, and condensed metal films.
Ionic Liquid Catalyst
[0051] Any type of ionic liquid catalyst may be regenerated in the
system and apparatus as described herein. Ionic liquid catalysts
are well known in the art. The system and apparatus as described
herein can employ a catalyst composition comprising at least one
aluminum halide such as aluminum chloride, at least one quaternary
ammonium halide and/or at least one amine halohydrate, and at least
one cuprous compound. Such a catalyst composition and its
preparation is disclosed in U.S. Pat. No. 5,750,455, which is
incorporated by reference in its entirety herein.
[0052] Alternatively, the ionic liquid catalyst can be a pyridinium
or imidazolium-based chloroaluminate ionic liquid. These ionic
liquids have been found to be much more effective in the alkylation
of isopentane and isobutane with ethylene than aliphatic ammonium
chloroaluminate ionic liquid (such as tributyl-methyl-ammonium
chloroaluminate). The ionic liquid catalyst can be (1) a
chloroaluminate ionic liquid catalyst comprising a hydrocarbyl
substituted pyridinium halide of the general formula A below and
aluminum trichloride or (2) a chloroaluminate ionic liquid catalyst
comprising a hydrocarbyl substituted imidazolium halide of the
general formula B below and aluminum trichloride. Such a
chloroaluminate ionic liquid catalyst can be prepared by combining
1 molar equivalent hydrocarbyl substituted pyridinium halide or
hydrocarbyl substituted imidazolium halide with 2 molar equivalents
aluminum trichloride. The ionic liquid catalyst can also be (1) a
chloroaluminate ionic liquid catalyst comprising an alkyl
substituted pyridinium halide of the general formula A below and
aluminum trichloride or (2) a chloroaluminate ionic liquid catalyst
comprising an alkyl substituted imidazolium halide of the general
formula B below and aluminum trichloride. Such a chloroaluminate
ionic liquid catalyst can be prepared by combining 1 molar
equivalent alkyl substituted pyridinium halide or alkyl substituted
imidazolium halide to 2 molar equivalents of aluminum
trichloride.
##STR00001##
wherein R.dbd.H, methyl, ethyl, propyl, butyl, pentyl or hexyl
group and X is a haloaluminate and preferably a chloroaluminate,
and R.sub.1 and R.sub.2.dbd.H, methyl, ethyl, propyl, butyl,
pentyl, or hexyl group and where R.sub.1 and R.sub.2 may or may not
be the same.
[0053] The ionic liquid catalyst can also be mixtures of these
chloroaluminate ionic liquid catalysts. Preferred chloroaluminate
ionic liquid catalysts are 1-butyl-4-methyl-pyridinium
chloroaluminate (BMP), 1-butyl-pyridinium chloroaluminate (BP),
1-butyl-3-methyl-imidazolium chloroaluminate (BMIM), 1-H-pyridinium
chloroaluminate (HP), and N-butylpyridinium chloroaluminate
(C.sub.5H.sub.5NC.sub.4H.sub.9Al.sub.2Cl.sub.7), and mixtures
thereof.
[0054] A metal halide may be employed as a co-catalyst to modify
the catalyst activity and selectivity. Commonly used halides for
such purposes include NaCl, LiCl, KCl, BeCl.sub.2, CaCl.sub.2,
BaCl.sub.2, SiCl.sub.2, MgCl.sub.2, PbCl.sub.2, CuCl, ZrCl.sub.4,
and AgCl as published by Roebuck and Evering (Ind. Eng. Chem. Prod.
Res. Develop., Vol. 9, 77, 1970), which is incorporated by
reference in its entirety herein. Especially useful metal halides
are CuCl, AgCl, PbCl.sub.2, LiCl, and ZrCl.sub.4. Another useful
metal halide is AlCl.sub.3.
[0055] HCl or any Broensted acid may be employed as an effective
co-catalyst to enhance the activity of the catalyst by boosting the
overall acidity of the ionic liquid-based catalyst. The use of such
co-catalysts and ionic liquid catalysts that are useful in
practicing the present process are disclosed in U.S. Published
Patent Application Nos. 2003/0060359 and 2004/0077914, the
disclosures of which are herein incorporated by reference in their
entirety. Other co-catalysts that may be used to enhance the
catalytic activity of the ionic liquid catalyst include IVB metal
compounds preferably IVB metal halides such as TiCl.sub.3,
TiCl.sub.4, TiBr.sub.3, TiBr.sub.4, ZrCl.sub.4, ZrBr.sub.4,
HfC.sub.4, and HfBr.sub.4 as described by Hirschauer et al. in U.S.
Pat. No. 6,028,024, which document is incorporated by reference in
its entirety herein.
Regeneration Conditions
[0056] Regeneration, according to the present system or in the
present apparatus, can be carried out at a temperature of 20 to
150.degree. C. Alternatively, regeneration can be carried out at a
temperature of 60 to 120.degree. C. In general, the temperature
will depend upon the type of ionic liquid catalyst and the type of
conjunct polymers present. At higher temperatures, the reaction is
faster. However, at high temperatures the ionic liquid catalyst may
begin to decompose. If hydrogen is not used, the pressure can be
autogenic. With hydrogen, any pressure necessary to give the
advantage of hydrogen can be employed. Any ratio of ionic liquid
catalyst to solvent can be employed, for example, 0.5 to 2
(vol/vol). At higher ratios, extraction is easier, but more costly.
The residence time depends upon temperature and the extent of
regeneration, but for an alkylation process, the residence time can
be 5 minutes to 1.5 hours.
[0057] It is not necessary to regenerate the entire charge of
catalyst from a process (e.g. alkylation) in the system and
apparatus as described herein. In some instances, only a portion or
slipstream of the catalyst charge is regenerated. In those
instances, the portion regenerated can be the amount necessary to
maintain a desired level of catalyst activity in the process that
ionic liquid catalyzes.
[0058] Although the present system and apparatus have been
described in connection with specific embodiments thereof, it will
be appreciated by those skilled in the art that additions,
deletions, modifications, and substitutions not specifically
described may be made without departing from the spirit and scope
of the system and apparatus as defined in the appended claims.
* * * * *