U.S. patent application number 13/938026 was filed with the patent office on 2013-11-14 for regeneration of acidic ionic liquid catalysts.
This patent application is currently assigned to CHEVRON U.S.A. INC.. The applicant listed for this patent is Saleh Ali Elomari, Thomas Van Harris. Invention is credited to Saleh Ali Elomari, Thomas Van Harris.
Application Number | 20130303358 13/938026 |
Document ID | / |
Family ID | 38174404 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130303358 |
Kind Code |
A1 |
Elomari; Saleh Ali ; et
al. |
November 14, 2013 |
REGENERATION OF ACIDIC IONIC LIQUID CATALYSTS
Abstract
We provide a process for regenerating a used acidic ionic liquid
catalyst which has been deactivated by conjunct polymers in a
reactor, by removing at least 57 wt % of the conjunct polymers
originally present in the used acidic ionic liquid catalyst in a
separate regeneration reactor, so as to increase the activity of
the catalyst. We also provide a regenerated used acidic ionic
liquid catalyst having increased activity.
Inventors: |
Elomari; Saleh Ali;
(Fairfield, CA) ; Harris; Thomas Van; (Benicia,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Elomari; Saleh Ali
Harris; Thomas Van |
Fairfield
Benicia |
CA
CA |
US
US |
|
|
Assignee: |
CHEVRON U.S.A. INC.
San Ramon
CA
|
Family ID: |
38174404 |
Appl. No.: |
13/938026 |
Filed: |
July 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12763924 |
Apr 20, 2010 |
8507396 |
|
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13938026 |
|
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|
11315749 |
Dec 20, 2005 |
7732363 |
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12763924 |
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Current U.S.
Class: |
502/22 ;
502/231 |
Current CPC
Class: |
B01J 35/12 20130101;
B01J 38/50 20130101; B01J 2231/20 20130101; B01J 2231/12 20130101;
C07D 213/20 20130101; B01J 2231/4205 20130101; B01J 2531/31
20130101; B01J 27/32 20130101; B01J 31/4092 20130101; B01J 38/54
20130101; Y02P 20/584 20151101; B01J 31/0288 20130101; B01J 27/30
20130101; C01B 17/905 20130101; B01J 31/0298 20130101; B01J 31/0284
20130101; B01J 2231/44 20130101 |
Class at
Publication: |
502/22 ;
502/231 |
International
Class: |
B01J 27/32 20060101
B01J027/32 |
Claims
1. A process for regenerating a used acidic ionic liquid catalyst
which has been deactivated by conjunct polymers in a reactor,
comprising removing conjunct polymers originally present in the
used acidic ionic liquid catalyst in a separate regeneration
reactor, so as to increase an activity of the used acidic ionic
liquid catalyst.
2. The process according to claim 1, wherein at least 57 wt % of
the conjunct polymers originally present in the used acidic ionic
liquid catalyst are removed.
3. The process according to claim 2, wherein greater than 90 wt %
of the conjunct polymers originally present in the used acidic
ionic liquid catalyst are removed.
4. The process according to claim 2, wherein up to 98.4 wt % of the
conjunct polymers originally present in the used acidic ionic
liquid catalyst are removed.
5. The process according to claim 1, wherein the used acidic ionic
liquid catalyst has been used to catalyze a Friedel-Craft
reaction.
6. The process according to claim 1, wherein the used acidic ionic
liquid catalyst comprises an imidazolium, pyridinium, phosphonium
or tetralkylammonium derivative, or their mixtures.
7. The process according to claim 1, wherein the used acidic ionic
liquid catalyst is a chloroaluminate ionic liquid.
8. The process according to claim 1, wherein the removing of the
conjunct polymers produces a regenerated ionic liquid catalyst
having better activity than a fresh ionic liquid catalyst from
which the used acidic ionic liquid catalyst was made.
9. The process according to claim 1, wherein the removing of the
conjunct polymers produces a regenerated ionic liquid catalyst
having a selectivity that is identical to an original selectivity
of a fresh ionic liquid catalyst.
10. The process according to claim 1, wherein a level of conjunct
polymers in the used acidic ionic liquid catalyst which has been
deactivated is at least 15.5 wt %.
11. The process according to claim 1, wherein the used acidic ionic
liquid catalyst which has been deactivated is introduced
continuously into the regeneration reactor.
12. A regenerated chloroaluminate ionic liquid catalyst.
13. The regenerated chloroaluminate ionic liquid catalyst of claim
12, wherein at least 57 wt % of conjunct polymers originally
present in a used chloroaluminate ionic liquid catalyst have been
removed.
14. The regenerated chloroaluminate ionic liquid catalyst of claim
13, wherein the regenerated chloroaluminate ionic liquid catalyst
has better activity for a paraffin alkylation than a fresh catalyst
from which the used chloroaluminate ionic liquid catalyst was
made.
15. The regenerated chloroaluminate ionic liquid catalyst of claim
13, wherein the regenerated chloroaluminate ionic liquid catalyst
has better activity for a paraffin alkylation than a fresh catalyst
from which the used chloroaluminate ionic liquid catalyst was made,
and wherein a selectivity of the regenerated chloroaluminate ionic
liquid catalyst for the paraffin alkylation is identical to an
original selectivity of the fresh catalyst.
16. The regenerated chloroaluminate ionic liquid catalyst of claim
13, wherein a selectivity of the regenerated chloroaluminate ionic
liquid catalyst for a paraffin alkylation is identical to an
original selectivity of a fresh catalyst from which the used
chloroaluminate ionic liquid catalyst was made.
17. The regenerated chloroaluminate ionic liquid catalyst of claim
12, comprising 4 to 7.9 wt % conjunct polymers and having increased
activity for a paraffin alkylation compared to a used
chloroaluminate ionic liquid catalyst before a regeneration.
18. A process for regenerating a used acidic ionic liquid catalyst
which has been deactivated by complexation with conjunct polymers
by freeing the conjunct polymers from complexation so as to
increase an activity of the used acidic ionic liquid catalyst.
19. A process for regenerating a used H.sub.2SO.sub.4 acidic
catalyst by removing conjunct polymers so as to increase an
activity of the used H.sub.2SO.sub.4 acidic catalyst.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/763,924, published as US 2010-0248940 A1,
herein incorporated in its entirety. This application is also a
continuation of U.S. patent application Ser. No. 11/315,749 now
granted as U.S. Pat. No. 7,732,363, herein incorporated in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to methods for the
regeneration of catalysts and more specifically to the regeneration
of acidic catalysts and to acidic ionic liquid catalysts.
BACKGROUND OF THE INVENTION
[0003] Ionic liquids are liquids that are composed entirely of
ions. The so-called "low temperature" Ionic liquids are generally
organic salts with melting points under 100 degrees C., often even
lower than room temperature. Ionic liquids may be suitable for
example for use as a catalyst and as a solvent in alkylation and
polymerization reactions as well as in dimerization,
oligomerization acetylation, metatheses, and copolymerization
reactions.
[0004] One 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] Ionic liquids can be defined as liquids whose make-up is
entirely comprised 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. Ionic liquids of pyridinium and
imidazolium are perhaps the most commonly used cations. Anions
include, but not limited to, BF.sub.4.sup.-, PF.sub.6.sup.-,
haloaluminates such as Al.sub.2Cl.sub.7.sup.- and
Al.sub.2Br.sub.7--, [(CF.sub.3SO.sub.2).sub.2N)].sup.-, alkyl
sulphates (RSO.sub.3.sup.-), carboxylates (RCO.sub.2.sup.-) and
many other. 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).
Chloroaluminate ionic liquids are perhaps the most commonly used
ionic liquid catalyst systems.
[0006] Examples of such low temperature ionic liquids or molten
fused salts are the chloroaluminate salts. Alkyl imidazolium or
pyridinium salts, for example, can be mixed with aluminum
trichloride (AlCl.sub.3) to form the fused chloroaluminate salts.
The use of the fused salts of 1-alkylpyridinium chloride and
aluminum trichloride as electrolytes is discussed in U.S. Pat. No.
4,122,245. Other patents which discuss the use of fused salts from
aluminum trichloride and alkylimidazolium halides as electrolytes
are U.S. Pat. Nos. 4,463,071 and 4,463,072.
[0007] U.S. Pat. No. 5,104,840 to 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.
[0008] U.S. Pat. No. 6,096,680 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.
[0009] 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 including
alkylations.
[0010] Other examples of ionic liquids and their methods of
preparation may also be found in U.S. Pat. Nos. 5,731,101;
6,797,853 and in U.S. Patent Application Publications 2004/0077914
and 2004/0133056.
[0011] Hydrogenation in chloroaluminate ionic liquids in the
presence of an electropositive metal and HCl was reported by K. R.
Seddon et al in Chem. Commun., 1999, 1043-1044.
[0012] As a result of use, ionic liquid catalysts become
deactivated, i.e. lose activity, and may eventually need to be
replaced. However, ionic liquid catalysts are expensive and
replacement adds significantly to operating expenses by in some
cases requiring shut down of an industrial process. One of the
heretofore unsolved problems impeding the commercial use of
chloroaluminate ionic liquid catalysts has been the inability to
regenerate and recycle them. The present invention provides methods
to regenerate acidic chloroaluminate ionic liquid catalysts
overcoming this obstacle and paving the way for the practical,
commercial use of these environmentally friendly catalysts.
SUMMARY OF THE INVENTION
[0013] Among other things the present invention provides a process
for regenerating a used acidic catalyst which has been deactivated
by conjunct polymers by removing the conjunct polymers so as to
increase the activity of the catalyst. Methods for removing the
conjunct polymers include, but are not limited to, hydrogenation,
addition of a basic reagent and alkylation. The methods are
applicable to all acidic catalysts and are described with reference
to certain ionic liquid catalysts.
BRIEF DESCRIPTION OF THE DRAWING
[0014] The FIGURE is a process diagram of an embodiment of a
process in accordance with the invention.
DETAILED DESCRIPTION
[0015] The present invention relates to a process for the
regeneration of spent or deactivated acidic catalysts, including
acidic ionic liquid-based catalysts i.e. those catalysts which have
lost all or some of their catalytic activity. The present process
is being described and exemplified with reference certain specific
ionic liquid catalysts and processes catalyzed thereby, but such
description is not intended to limit the scope of the invention.
The methods described may be applied to other catalysts and
processes by those persons having ordinary skill based on the
teachings, descriptions and examples included herein.
[0016] The specific examples used herein refer to alkylation
processes using ionic liquid systems, which are amine-based
cationic species mixed with aluminum chloride. In such systems, to
obtain the appropriate acidity suitable for the alkylation
chemistry, the ionic liquid catalyst is generally prepared to full
acidity strength by mixing one molar part of the appropriate
ammonium chloride with two molar parts of aluminum chloride. The
catalyst exemplified for the alkylation process is a
1-alkyl-pyridinium chloroaluminate, such as 1-butyl-pyridinium
heptachloroaluminate.
##STR00001##
[0017] In general, a strongly acidic ionic liquid is necessary for
paraffin alkylation, e.g. isoparaffin alkylation. In that case,
aluminum chloride, which is a strong Lewis acid in a combination
with a small concentration of a Broensted acid, is a preferred
catalyst component in the ionic liquid catalyst scheme.
[0018] While not being bound to this or any other theory of
operation, the present invention is based in part on our discovery
that one of the major catalyst deactivation mechanisms is the
formation of by-products known as conjunct polymers. 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 unsaturated intricate network of molecules that
may include one or a combination of 4-, 5-, 6- and 7-membered rings
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). These molecules contain
double and conjugated double bonds in intricate structures
containing a combination of cyclic and acyclic skeletons.
[0019] The conjunct polymers deactivate the chloroaluminate ionic
liquid catalysts by weakening the acid strength of the catalyst
through the formation of complexes of conjunct polymers and
AlCl.sub.3 possibly by means of electron-donor/electron-acceptor
interactions. The conjunct polymers with their double bonds are the
donors and the Lewis acid (AlCl.sub.3) is the acceptor. Using their
double bonds, the conjunct polymers coordinate to the Lewis acid
(AlCl.sub.3) in the ionic liquid and rendering the coordinated
AlCl.sub.3 for catalysis. Thus, the acidity of the catalyst becomes
weaker and the overall catalytic activity becomes compromised and
no longer effective for the intended purpose. Thus, the catalyst
performance will become a function of the concentration of conjunct
polymers in the ionic liquid phase. As more conjunct polymers
accumulate in the ionic liquid phase the catalyst becomes less
active. So, removal of all or a suitable portion of the conjunct
polymers from the ionic liquid phase is a significant aspect of the
present process for ionic liquids catalyst regeneration.
[0020] The term "conjunct polymer" as used herein also includes any
other species which might complex to AlCl.sub.3 by pi bonding or
sigma bonding or other means, which results in those species
binding to the ionic liquid, so they are not removable by simple
hydrocarbon extraction.
[0021] The formation of conjunct polymers has also been observed in
other acidic catalysts used in acid-catalyzed reactions, including
HF, H.sub.2SO.sub.4 and AlCl.sub.3 alkylations. 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. The methods of the present invention are applicable to
those catalysts and processes.
[0022] It is believed that deactivation of the catalyst by the
presence of conjunct polymers is, in part at least, caused by
coordination and complex formation between the Lewis acid
AlCl.sub.3 (electron pair acceptor) and the conjunct polymers
(electron donors). In such complexes, the AlCl.sub.3 is no longer
available to act as a catalyst since it is tied-up in the
AlCl.sub.3-conjunct polymers complexes. It also appears that the
presence (or accumulation) of conjunct polymer molecules in the
catalyst phase is not by virtue of being miscible in the ionic
liquid phase. While conjunct polymers may be somewhat miscible in
the ionic liquids, their accumulation in the catalyst phase is more
likely to being bound by strong acid-base interactions
(complexation) rather than being soluble in the ionic liquid
phase.
[0023] Conjunct polymers isolated from the catalyst phase by means
of hydrolysis are highly soluble in hydrocarbons. However, attempts
to remove them from the catalyst phase prior to hydrolysis by
simple extraction methods with hydrocarbon solvents such as hexane,
decane and toluene were unsuccessful. Other more polar solvents
such as CH.sub.2Cl.sub.2 or chloroform may dissolve a
chloroaluminate ionic liquid and therefore are not a selective
solvent for dissolving and removing the conjunct polymers. Conjunct
polymers may be isolated by hydrolysis. However, these methods of
isolating the conjunct polymers are destructive, and result in an
actual loss of a catalytic component (AlCl.sub.3). The hydrolysis
methods hydrolyze the catalytic component (AlCl.sub.3) and
transform it into inactive aluminum hydroxide and aluminum oxide.
This indicates that the conjunct polymers are tightly held in the
ionic liquid phase by fairly strong type of bonding system.
Therefore, any successful attempt to reactivate and regenerate the
catalyst must involve the removal of conjunct polymers to release
aluminum trichloride from the AlCl.sub.3-conjunct polymer complexes
without destroying, consuming, or irreversibly tying up the
AlCl.sub.3.
[0024] In other words, one objective is to free the catalyst by
replacing the conjunct polymers with other basic species that
simply displace the polymer without destroying the catalyst or by
suppressing the ability of conjunct polymers to form complexes with
Lewis acids (aluminum chloride).
[0025] The deactivated catalyst can be revived in a nondestructive
manner by freeing up the AlCl.sub.3 from conjunct
polymer-AlCl.sub.3 complex. In principle, this can be accomplished
by saturation of the double bonds of the conjunct polymers to
eliminate their ability to coordinate to the Lewis acid
(AlCl.sub.3). By hydrogenation, the double bonds of the conjunct
polymers will be saturated and no longer be able to be coordinated
or complexed to AlCl.sub.3. AlCl.sub.3 no longer bound by conjunct
polymers is then released to take part in catalytic reactions.
[0026] Among other things the present invention provides a process
for the removal of the conjunct polymers from a used ionic liquid
catalyst by saturating the double bonds of the conjunct polymers by
means of hydrogenation thereby increasing the activity of the ionic
liquid catalyst.
[0027] Hydrogenation is a well-established process both in the
chemical and petroleum refining industries. Hydrogenation is
conventionally carried out in the presence of a catalyst which
usually comprises a metal hydrogenation component on a porous
support material, such as a natural clay or a synthetic oxide.
Nickel is often used as a hydrogenation component, as are noble
metals such as platinum, palladium, rhodium and iridium. Typical
support materials include kieselguhr, alumina, silica and
silica-alumina. Depending upon the ease with which the feed may be
hydrogenated, the hydrogen pressures used may vary from quite low
to very high values, typically from about 100 to 2,500 psig.
[0028] The hydrogenation catalyst used in this invention may be any
one of metallic or non-metallic catalysts which have hydrogenating
ability. The preferred catalyst comprises at least one
hydrogenation component selected from Group VI-B and VIII, present
as metals, oxides, or sulfides. Specific examples of the metallic
catalysts are Fe, Co, Ni, Ru, Rh, Pd, Ir, Os, Pt, Cr, Mn, Ti, V,
Zr, Mo, and W. Specific examples of the non-metallic catalysts are
Te and As. These metals or non-metals may be used singly or in
combination.
[0029] Noble metals such as palladium, platinum, or ruthenium,
applied to diverse supports such as silicon dioxide, aluminum
oxide, graphite, or activated charcoal, are well suited for the
hydrogenation of organic and inorganic compounds. The hydrogenation
component may also be supported on a refractory inorganic base, for
example, alumina, silica, and composites of alumina-silica,
alumina-boria, silica-alumina-magnesia, and silica-alumina-titania
and materials obtained by adding zeolites and other complex oxides
thereto. The refractory inorganic oxide is a material that has
adequate mechanical strength and chemical stability at the reaction
temperature of the catalyst.
[0030] The catalyst of the present invention can be manufactured by
supporting catalytically active components on a catalyst carrier.
The active components may be deposited on the surface of the
catalyst carrier after the carrier has been formed, or they may be
incorporated into the catalyst by being added to the carrier
material during the formation of the catalyst carrier. Many such
methods of preparation are known.
[0031] Hydrogenation may also be accomplished by using a metal or
metal alloy hydrogenation catalyst. This hydrogenation catalyst may
be any one of the various metallic catalysts which have
hydrogenating ability. The preferred catalyst is selected from
Group VI-B and VIII. Specific examples of the metallic catalysts
are Fe, Co, Ni, Ru, Rh, Pd, Ir, Os, Pt, Cr, Mn, Ti, V, Zr, Mo, and
W. These metals may be used singly, in combination or as alloys.
Catalysts such as Raney nickel and alloys such as Ni/Al alloy may
also be suitably employed.
[0032] The metals can be in the form of fine particles, granules,
sponges, gauzes, etc. Each metal may be used in any number of
forms: (1) macroscopic, which includes wires, foils, fine
particles, sponges, gauzes, granules, etc.; and (2) microscopic,
which includes powders, smokes, colloidal suspensions, and
condensed metal films.
[0033] It is known that Raney-type-metal catalysts are prepared
from alloys containing one or more catalytically 25 active metals
(e.g., Ni, Co, Fe, Cu, Pd, etc.) and one or more catalytically
inactive, easily dissolvable metals (e.g., Al, Si, Mg, Zn). The
catalytically active metal component of the alloy is present in a
so-called "dissolved" state, i.e. in a finely divided form. The
inactive component is removed from the alloy by leaching the same
with a solvent which does not attack the active metal. As solvents,
generally aqueous alkaline solutions are used. During this
procedure the active metal remains in the form of finely divided
catalyst. The activity of the thus-obtained catalysts is higher
than that of catalysts prepared, e.g., by reducing the appropriate
metal oxides. This high activity explains the importance and the
widespread use of such catalysts.
[0034] Hydrogenation may also be accomplished using a homogeneous
hydrogenation catalyst. Numerous examples of such catalysts are
disclosed in U.S. Pat. No. 5,334,791, which is incorporated by
reference herein.
[0035] Homogeneous hydrogenation catalysts for the production of
hydrogenation reactants are well known in the art, with many
systems being based on rhodium metal combined with phosphine
ligands. Examples of such catalysts were first described in J. A.
Osborn, F. H. Jardine, J. F. Young and G. Wilkinson, J. Chem. Soc.
(A) (1966) 1711. Other examples are soluble (homogenous) metal
salts such as PdCl.sub.2 and NiCl.sub.2, and transition metal
complexes such as PdCl.sub.2(triphenylphosphine).sub.2 and
NiCl.sub.2(triphenylphosphine).sub.2. Other organic metal
complexes, e.g., organometallic compounds of Ti, Ru, Rh, Zr, etc.
are known to be useful homogeneous hydrogenation catalysts.
[0036] The Osborn et al. paper describes the hydrogenation of
hydrogenatable products using a catalyst precursor of the formula
[RhCl(triphenylphosphine).sub.3] and a pressure of hydrogen gas of
one atmosphere. U.S. Pat. No. 5,334,791 describes hydrogenation
process for non-aromatic unsaturated hydrocarbons using catalyst
precursors based on a group VIIIB transition metal and a phosphine
ligand.
[0037] Also of note is the use of chiral bis tertiary diphosphines
in asymmetric hydrogenation with rhodium(I) catalyst precursors.
There are a number of patents related to synthesis and application
of several rhodium-chiral diphosphine catalyst precursors: See for
example, U.S. Pat. Nos. 3,419,907; 3,849,490; 3,878,101; 4,166,824;
4,119,652; 4,397,787; 4,440,936.
[0038] Other homogeneous hydrogenation catalysts and their method
of preparation are described in F. Albert Cotton and Geoffrey
Wilkinson, "Advanced Inorganic Chemistry", Interscience Publishers,
New York, 3rd Edition, 1972, pp 787 to 790.
[0039] Hydrogenation of used ionic liquid catalyst is shown by the
following example. As noted previously, ionic liquid catalysts may
become deactivated during use. For example, in an alkylate
production unit, light (C.sub.2-C.sub.5) olefins and isoparaffin
feeds are contacted in the presence of a catalyst that promotes the
alkylation reaction. In one embodiment of a process in accordance
with the present invention, this catalyst is a chloroaluminate
ionic liquid. The reactor, which may be a stirred tank or other
type of contactor (e.g., riser reactor), produces a biphasic
mixture of alkylate hydrocarbons, unreacted isoparaffins, and ionic
liquid catalyst containing some conjunct polymers. The dense
catalyst/conjunct polymer phase may be separated from the
hydrocarbons by gravity decanter. This catalyst will be partially
deactivated by the conjunct polymers binding to AlCl.sub.3. The
recovered catalyst can be reactivated in a reaction system
hydrogenation with a supported hydrogenation catalyst. The products
of this step will be reactivated catalyst and hydrogenated conjunct
polymers among others as described herein. The reactivated catalyst
and the hydrogenated conjunct polymers can be separated, for
example, by solvent washing, decantation, and filtration.
[0040] In one embodiment of the present invention using
hydrogenation, a used ionic liquid catalyst/conjunct polymer
mixture is introduced continuously into a regeneration reactor,
which contains a fixed bed of a supported hydrogenation catalyst.
Hydrogen gas and inert hydrocarbons in which hydrogenated conjunct
polymers are soluble are fed into the reactor at the desired rate.
The solvent may be a normal hydrocarbon ranging from
C.sub.5-C.sub.15, preferably C.sub.5-C.sub.8. The residence time,
temperature and pressure of the reactor will be selected to allow
adequate hydrogenation of the conjunct polymers. The reaction
product is withdrawn and sent to a separator. This mixture is then
separated into three streams, one comprising hydrogen and light
hydrocarbons, a second comprising inert hydrocarbons and saturated
conjunct polymer and a third comprising regenerated ionic liquid
catalyst. The denser and more viscous regenerated catalyst phase
settles to the bottom and can be recovered by means of a gravity
decanter. The reactivated ionic liquid catalyst is returned to the
alkylation reactor. The solvent/conjunct polymer mix is separated
by distillation to recover the solvent.
[0041] A metal and a Broensted acid are used for hydrogenation in
another embodiment of the present invention, which is described
using aluminum and HCl. Aluminum metal reacts with HCl to give
hydrogen gas and AlCl.sub.3. By introducing aluminum metal and HCl
into ionic liquid catalysts deactivated by conjunct polymers, the
hydrogen liberated can be used to saturate the conjunct polymer
double bonds. Concurrently, fresh aluminum chloride is produced,
which is the acid component in the chloroaluminate ionic liquid.
This constitutes a two-function regeneration scheme for both
hydrogenating the conjunct polymers to release the complexed
AlCl.sub.3 and producing fresh AlCl.sub.3 which replenishes
AlCl.sub.3 that has been consumed or lost by other means during the
reaction. The hydrogenated conjunct polymers can be removed by
solvent extraction or decantation and the regenerated ionic liquid
catalyst recovered by filtration. Our experiments have shown that
this scheme is feasible and that the regenerated catalyst
demonstrated equal or better activity for the alkylation of
ethylene with isopentane compared with freshly prepared
catalyst.
[0042] As seen from the prior description, an embodiment of a
process according to the present invention utilizes hydrogenation
to saturate the double bonds of conjunct polymers using aluminum
metal and hydrochloric acid. Using aluminum metal and HCl will
produce the needed hydrogen gas for the hydrogenation and will also
produce fresh AlCl.sub.3 that increases the acidity and the
activity of the recycled catalyst by increasing the concentration
of AlCl.sub.3 in the ionic liquid to its upper limits. In some
cases, the regenerated catalyst will be more active than the
freshly prepared catalyst prior to being deactivated. The metal
used in the regeneration process in accordance with the present
invention is not limited to aluminum. Other electropositive metals
will react with HCl to produce H.sub.2 and the corresponding metal
chloride can also be used. This includes sodium, lithium, zinc,
iron, copper, magnesium, titanium, gallium and many others.
Aluminum metal will be the metal of choice when chloroaluminate
ionic liquids are used in the catalytic process to avoid
contamination of the regenerated ionic liquid with metal chlorides
other than AlCl.sub.3. While some metal chlorides may work as
co-catalyst, others may inhibit the alkylation mechanism and
promote unwanted reaction pathway. The process is not limited to
using HCl as the source of hydrogen. Other Broensted acids may also
be used as a source of hydrogen including, but not limited to, HI,
HBr, HF, H.sub.2SO.sub.4, H.sub.3PO.sub.4. In the case of
chloroaluminate ionic liquids, hydro halides (HI, HCl, HBr, HF)
will be the acids of choice. Among the hydro halides hydrochloric
acid is preferred to avoid introduction of conjugate bases other
than halides and preferably other than chlorides.
[0043] As shown in the Examples, the conjunct polymers are removed
by hydrogenation using aluminum and hydrogen chloride. Adding
aluminum and hydrogen chloride to used ionic liquid catalyst and
stirring the resulting mixture (in autoclave) at room temperature
or at 50.degree. C. at the autogenic pressure led to removal of
>90% of the conjunct polymers as hydrogenated hydrocarbons. The
hydrogenated conjunct polymers (immiscible in the ionic liquid
phase) were removed by simple extraction methods with other
hydrocarbons (such as hexanes) or by means of decantation. The
regenerated ionic liquid catalyst was removed from the remaining
mixture (freshly made AlCl.sub.3 and aluminum metal) by
filtration.
[0044] The recovered regenerated ionic liquid catalyst was tested
for activity by alkylating ethylene with isopentane and the
regenerated catalyst showed better activity than both the
deactivated catalyst and the fresh catalyst from which the
deactivated catalyst was made. The selectivity of the regenerated
catalyst was identical to the selectivity of the freshly-made
catalyst.
[0045] In an alkylate production unit, light (C.sub.2-C.sub.5)
olefins and isoparaffin feeds are contacted in the presence of a
catalyst that promotes the alkylation reaction. In one embodiment
of a process in accordance with the present invention, this
catalyst is a chloroaluminate ionic liquid. The reactor, which may
be a stirred tank or other type of contactor (e.g., riser reactor),
produces a biphasic mixture of alkylate hydrocarbons, unreacted
isoparaffins, and ionic liquid catalyst containing some conjunct
polymers. The catalyst/conjunct polymer phase may be separated from
the hydrocarbons by means of a gravity decanter. This catalyst will
be partially deactivated by the conjunct polymers binding to
AlCl.sub.3. The recovered catalyst can be reactivated in a reaction
system employing aluminum metal and HCl. The products of this step
will be reactivated catalyst and hydrogenated conjunct polymers.
These can be separated by solvent washing, decantation, and
filtration.
[0046] It is not necessary to regenerate the entire charge of
catalyst. In some instances only a portion or slipstream of the
catalyst charge is regenerated. In those instances only as much
ionic liquid catalyst is regenerated as is necessary to maintain a
desired level of catalyst activity in the process in which the
ionic liquid is used as the catalyst.
[0047] In one embodiment of the present invention with reference to
the FIGURE, the ionic liquid catalyst/conjunct polymer mixture is
introduced continuously into a stirred tank reactor (CSTR), where
aluminum metal powder is added by way of a screw-type feeder. The
aluminum is kept under inert gas (nitrogen or other) to prevent
oxidation. HCl gas is fed in at the desired rate to produce H.sub.2
gas and AlCl.sub.3. The residence time of the reactor will be
selected to allow adequate hydrogenation of the conjunct polymers.
The reaction product is withdrawn and mixed with a hydrocarbon
solvent (e.g., hexane) in which the hydrogenated conjunct polymers
are soluble. The solvent may be a normal hydrocarbon ranging from
C.sub.5-C.sub.15; preferably C.sub.5-C.sub.8. This mixture is then
separated in a gravity decanter, from which the dense ionic liquid
phase is withdrawn. Unreacted aluminum in the ionic liquid phase is
removed by filtration. The reactivated ionic liquid catalyst is
returned to the alkylation reactor. The solvent/conjunct polymer
mix is separated by distillation to recover the solvent.
[0048] Hydrogenation conditions for all types of hydrogenation
described herein will generally include temperatures of -20.degree.
C.-200.degree. C., preferably 50.degree.-150.degree. C., pressures
of atmospheric-5000 psig, preferably 50-500 psig, and a contact
time of 0.1 minute-24 hours, and preferably from 1/2-2 hours in a
normal hydrocarbon as a solvent.
[0049] In another embodiment of the present invention, an acidic
catalyst is regenerated by adding a basic reagent which breaks up
AlCl.sub.3-conjunct polymer complexes.
[0050] There are numerous reagents that can be used to break up the
AlCl.sub.3-conjunct polymer complexes including, e.g. amines. One
important consideration is that any of these basic species would
form, most likely, irreversible complexes with AlCl.sub.3 similar
to the AlCl.sub.3-conjunct polymer complexes. Moreover, there is no
selective method to break up AlCl.sub.3-conjunct polymer complexes.
In other words, any reagent that may be used to break up the
AlCl.sub.3-conjunct polymer complexes will also react with other
aluminum species in the catalyst phase Therefore, to ensure the
complete break-up of the complexes by a reagent, sufficient reagent
must be added to react with all AlCl.sub.3 molecules in the system,
both bound and unbound.
[0051] Since any reagent to be used in the removal process of
conjunct polymers from the spent catalyst will form new complexes
(e.g. AlCl.sub.3-reagent complexes), thereby destroying active
catalytic components, there will be no gain from this procedure
unless the reagent to be used is part of the catalyst system
undergoing regeneration. Consequently, a process according to this
invention, employs basic species that can displace the conjunct
polymers and be part of the regeneration or recycling process of
the catalyst. For example, in the butyl-pyridinium chloroaluminate
ionic liquid catalyst system, butylpyridinium chloride, where the
chloride is the basic specie, would be used to break up the
AlCl.sub.3-conjunct polymer complexes in the spent catalyst.
[0052] Where, for example, the ionic liquid is formed by mixing
either an amine hydrochloride or an alkyl ammonium halide with a
Lewis acid, in accordance with the present invention, a process
whereby aluminum chloride is released from the AlCl.sub.3-conjunct
polymer complex is conducted by using either amines or ammonium
chloride depending on the ionic liquid that is being regenerated.
More specifically, for 1-butyl-pyridinium heptachloroaluminate, the
conjunct polymers are released by adding butyl-pyridinium chloride
to the deactivated catalyst. The chloride of the 1-butyl-pyridinium
chloride interacts with the non-complexed and complexed aluminum
species in the spent catalyst phase and thus freeing the conjunct
polymers from the AlCl.sub.3-conjunct polymer complexes. The
released conjunct polymers are then removed, for example, by
extraction with low boiling n-paraffins. The remaining solid
residues, presumably butylpyridinium tetrachloroaluminate, are
converted back to ionic liquid (butylpyridinium
heptachloroaluminate) by adding more AlCl.sub.3 as set forth
below.
##STR00002##
[0053] Using this process, a stream of the catalyst is reactivated
and the regenerated catalyst is recycled back into the reactor. By
employing a method according to the invention, the concentration of
the conjunct polymers can be minimized while the catalyst strength
is maintained by reintroducing the regenerated catalyst into the
reaction cycle.
[0054] The principle used for selecting a suitable reagent is not
only limited to using butylpyridinium in butylpyridinium
chloroaluminate or butylpyridinium chloroaluminate-like ionic
liquids. It is applicable to ionic liquids in general. The reagent
is one which corresponds to the basic parent species of cation from
which the ionic liquid to be regenerated was originally
produced.
[0055] As a further example of this principle, consider ionic
liquids that were produced from ammonium hydrohalides and aluminum
chlorides. In this case, the basic reagent that is used to break up
the AlCl.sub.3-conjunct polymer complex is the free amine
corresponding to the ammonium hydrohalide salt. Conjunct polymers
are removed and ammonium tetrachloroaluminate is produced. Addition
AlCl.sub.3/HCl is used to re-constitute the ionic liquid.
[0056] In summary, for aluminum chloride-based ionic liquid
catalysts, a deactivated catalyst can be revived in a
nondestructive manner by freeing up the AlCl.sub.3 from conjunct
polymer-AlCl.sub.3 complex. The process employs the parent amine in
the case of an ionic liquid catalyst derived from ammonium
hydrochlorides and aluminum halides, or employing alkyl ammonium
halides when the ionic liquid catalyst is derived from alkyl
ammonium halides and aluminum.
[0057] Addition of a basic reagent is shown by the following
example. In an alkylate production unit, light (C.sub.2-C.sub.5)
olefins and isoparaffin feeds are contacted in the presence of a
catalyst that promotes the alkylation reaction. In one embodiment
of a process in accordance with the present invention, this
catalyst is a chloroaluminate ionic liquid. The reactor, which may
be a stirred tank or other type of contactor (e.g., riser reactor),
produces a biphasic mixture of alkylate hydrocarbons, unreacted
isoparaffins, and ionic liquid catalyst containing some conjunct
polymers. The catalyst/conjunct polymer phase, which is denser than
other components, may be separated from the hydrocarbons by means
of a gravity decanter. This catalyst will be partially deactivated
by the conjunct polymers binding to AlCl.sub.3. The recovered
catalyst can be reactivated by first contacting the recovered
catalyst with butylpyridinium chloride in a first regeneration
reactor to give butylpyridinium tetrachloroaluminate and "free"
conjunct polymer. The free conjunct polymer is removed. The
remaining butylpyridinium tetrachloroaluminate is then sent to a
second regeneration reactor where it is contacted with AlCl.sub.3
to fully restore the activity of the catalyst. The regenerated
ionic liquid catalyst effluent of the second reactor is then
recycled to the alkylate production unit.
[0058] In one embodiment of the present invention using the
addition of a basic reagent, a used ionic liquid catalyst/conjunct
polymer mixture is introduced continuously into a regeneration
reactor along with butylpyridinium chloride and inert hydrocarbons
in which hydrogenated conjunct polymers are soluble at the desired
rate. The inert hydrocarbons may be a normal hydrocarbons ranging
from C.sub.5-C.sub.15, preferably C.sub.5-C.sub.8 and their
mixtures, although other hydrocarbons may be employed. A conjunct
polymer-hydrocarbon mixture is removed from the first regeneration
reactor. The remaining butylpyridinium tetrachloroaluminate is then
sent to a second regeneration reactor where it is contacted with
AlCl.sub.3 to fully restore the activity of the catalyst. The
regenerated ionic liquid catalyst is removed from the second
reactor and can then be recycled.
[0059] Another method of regenerating a used acidic catalyst in
accordance with the present invention is by reaction with an
isoparaffin in the presence of a Broensted acid, e.g. HCl. While
not being bound to any theory, we believe that reaction of
isobutane with the double bonds in the conjunct polymers leads to a
partial or complete "capping" (alkylating) of the conjunct polymers
double bonds disrupting their ability to complex to, e.g., aluminum
trichloride. This is supported by our discovery that olefin
oligomers can be terminated and saturated by carrying out the
chloroaluminate ionic liquid catalyzed oligomerization reaction in
the presence of isobutane.
[0060] In a process according to the present invention an
isoparaffin feedstock is used to reactivate a used acidic ionic
liquid catalyst. The simplest isoparaffin is isobutane.
Isopentanes, isohexanes, isopentanes, and other higher isoparaffins
may also be useable in the process of the present invention.
Mixtures of light isoparaffins can also be used in the present
invention. Mixtures such as C.sub.4-C.sub.5 isoparaffins can be
used and may be advantageous because of reduced separation costs.
The isoparaffin feedstock may also contain diluents such as normal
paraffins. This can be a cost savings by reducing the cost of
separating isoparaffins from close boiling paraffins. Normal
paraffins will tend to be unreactive diluents in the process of the
present invention.
[0061] A preferred isoparaffin is one which has a tertiary carbon
atom, i.e. one which is substituted by three alkyl or aryl groups
and has one remaining hydrogen and therefore is capable of
participating in hydride transfer reactions.
[0062] Broensted acids other than HCl may also be used in this
embodiment including, but not limited to, HI, HBr, HF,
H.sub.2SO.sub.4, H.sub.3PO.sub.4. In the case of chloroaluminate
ionic liquids, hydrohalides (HI, HCl, HBr and HF) will be the acids
of choice. Among the hydrohalides, hydrochloric acid is preferred.
Other strong acids that are proton donors may also be suitably
used.
[0063] In one example of this embodiment, the ionic liquid
catalyst/conjunct polymer mixture is introduced continuously into a
reactor. HCl gas and isobutane are fed in to the reactor at the
desired rate. The residence time of the reactor will be selected to
allow adequate alkylation of the conjunct polymers. The reaction
product is withdrawn and mixed with a hydrocarbon solvent (e.g.,
hexane) in which the released conjunct polymers are soluble. The
solvent may be normal hydrocarbons ranging from C.sub.5-C.sub.15;
preferably C.sub.5-C.sub.8 This mixture is then separated in a
gravity decanter, from which the denser ionic liquid phase is
withdrawn. The reactivated ionic liquid catalyst is returned to the
alkylation reactor. The solvent/conjunct polymer mix is separated
by distillation to recover the solvent.
[0064] Typical alkylation reaction conditions generally may include
a temperature of from -10.degree. C. to +150.degree. C., a pressure
of from 0 psig to 3500 psig, an isopentane to conjunct polymer
molar ratio of from 0.5 to 25 or more and a residence time of 0.5
min to 1 hour or longer
[0065] It is not necessary in any of the methods in accordance with
the invention to regenerate the entire charge of catalyst. In some
instances only a portion or slipstream of the catalyst charge is
regenerated. In those instances only as much ionic liquid catalyst
is regenerated as is necessary to maintain a desired level of
catalyst activity in the process in which the ionic liquid is used
as the catalyst.
[0066] The block diagram in the FIGURE is not meant to restrict the
present invention to any sort or type of reactor. Also, the FIGURE
shows an inert hydrocarbon entering the reactor together with the
deactivated ionic liquid. That is an optional implementation. The
hydrocarbon could be left out entirely or it could be added to the
separator to allow extraction and separation simultaneously. Other
modifications are possible and are included in the scope of the
present invention.
[0067] The following Examples are illustrative of the present
invention, but are not intended to limit the invention in any way
beyond what is contained in the claims which follow.
EXAMPLES
Example 1
Preparation of Fresh 1-Butylpyridinium Chloroaluminate Ionic Liquid
Catalyst A (Fresh IL A)
[0068] 1-butyl-pyridinium chloroaluminate is a room temperature
ionic liquid prepared by mixing neat 1-butyl-pyridinium chloride (a
solid) with neat solid aluminum trichloride in an inert atmosphere.
The syntheses of butylpyridinium chloride and the corresponding
1-butyl-pyridinium chloroaluminate are described below. In a 2-L
Teflon-lined autoclave, 400 gm (5.05 mol.) anhydrous pyridine
(99.9% pure purchased from Aldrich) were mixed with 650 gm (7 mol.)
1-chlorobutane (99.5% pure purchased from Aldrich). The autoclave
was sealed and the neat mixture allowed to stir at 125.degree. C.
under autogenic pressure over night. After cooling off the
autoclave and venting it, the reaction mix was diluted and
dissolved in chloroform and transferred to a three liter round
bottom flask. Concentration of the reaction mixture at reduced
pressure on a rotary evaporator (in a hot water bath) to remove
excess chloride, un-reacted pyridine and the chloroform solvent
gave a tan solid product. Purification of the product was done by
dissolving the obtained solids in hot acetone and precipitating the
pure product through cooling and addition of diethyl ether.
Filtering and drying under vacuum and heat on a rotary evaporator
gave 750 gm (88% yields) of the desired product as an off-white
shiny solid. .sup.1H-NMR and .sup.13C-NMR were consistent with the
desired 1-butyl-pyridinium chloride and no impurities were
observed.
[0069] 1-butylpyridinium chloroaluminate was prepared by slowly
mixing dried 1-butylpyridinium chloride and anhydrous aluminum
chloride (AlCl.sub.3) according to the following procedure. The
1-butylpyridinium chloride (prepared as described above) was dried
under vacuum at 80.degree. C. for 48 hours to get rid of residual
water (1-butylpyridinium chloride is hydroscopic and readily
absorbs water from exposure to air). Five hundred grams (2.91 mol.)
of the dried 1-butylpyridinium chloride were transferred to a
2-Liter beaker in a nitrogen atmosphere in a glove box. Then, 777.4
gm (5.83 mol.) of anhydrous powdered AlCl.sub.3 (99.99% from
Aldrich) were added in small portions (while stirring) to control
the temperature of the highly exothermic reaction. Once all the
AlCl.sub.3 was added, the resulting amber-looking liquid was left
to gently stir overnight in the glove box. The liquid was then
filtered to remove any un-dissolved AlCl.sub.3. The resulting
acidic 1-butyl-pyridinium chloroaluminate was used as the catalyst
for the alkylation of isopentane with ethylene.
##STR00003##
Example 2
Preparation of "Deactivated" 1-Butylpyridinium Chloroaluminate
Ionic Liquid Catalyst (Deactivated Catalyst A)
[0070] "Deactivated" or "used" 1-butylpyridinium chloroaluminate
ionic liquid catalyst was prepared from "fresh" 1-butylpyridinium
chloroaluminate ionic liquid catalyst by carrying out the isobutane
alkylation reaction in a continuous flow microunit under catalyst
recycle with accelerated fouling conditions.
[0071] The microunit consists of feed pumps for isobutane and
butenes, a stirred autoclave reactor, a back pressure regulator, a
three phase separator, and a third pump to recycle the separated
ionic liquid catalyst back to the reactor. The reactor was operated
at 80 to 100 psig pressure and with cooling to maintain a reaction
temperature of .about.10.degree. C. To start the reaction,
isobutane, butenes, and HCl were pumped into the autoclave at the
desired molar ratio (isobutane/butenes >1.0), through the back
pressure regulator, and into the three phase separator. At the same
time, fresh chloroaluminate ionic liquid catalyst was pumped into
the reactor at a rate pre-calculated to give the desired
catalyst/feed ratio on a volumetric basis. As the reaction
proceeded, ionic liquid separated from the reactor effluent and
collected in the bottom of the three phase separator. When a
sufficient level of catalyst built up in the bottom of the
separator, the flow of fresh ionic liquid was stopped and catalyst
recycle from the bottom of the separator was started. In this way,
the initial catalyst charge was continually used and recycled in
the process.
[0072] The following process conditions were used to generate
Deactivated Catalyst A (1-butylpyridinium chloroaluminate ionic
liquid catalyst) from Fresh Catalyst A:
TABLE-US-00001 Process Variable Isobutane pump rate 4.6 g/min
Butene pump rate 2.2 g/min IL Catalyst pump rate 1.6 g/min HCl flow
rate 3.0 SCCM pressure 100 psig temperature 10.degree. C.
[0073] The reaction was continued for 72 hours when it was judged
that the catalyst had become sufficiently deactivated.
Example 3
Determination of the Amounts of Conjunct Polymer and Olefin
Oligomers in Deactivated IL A
[0074] The wt % of conjunct polymers in the spent (deactivated)
ionic liquid was determined by hydrolysis of known weights of the
spent catalyst. The example below is a typical procedure for
measuring conjunct polymers in a given spent catalyst. In a glove
box, 15 gm of a spent ionic liquid catalyst in a flask were rinsed
first with 30-50 ml of anhydrous hexane to remove (from the spent
catalyst) any residual hydrocarbon or olefinic oligomers. The
hexane rinse was concentrated under reduced pressure to give only
0.02 gm of yellow oil (0.13%). Then, 50 ml of anhydrous hexane was
added to the rinsed catalyst followed by slow addition of 15 ml of
water, and the mixture was stirred at 0.degree. C. for 15-20
minutes. The resulting mixture was diluted with additional 30 ml
hexanes and stirred well for additional 5-10 minutes. The mixture
was allowed to settle down to two layers solution and some solid
residue. The organic layer was recovered by decanting. The aqueous
layer was further washed with additional 50 ml hexanes. The hexanes
layers were combined and dried over anhydrous MgSO.sub.4, filtered
and concentrated to give 2.5 gm (16.7 wt % of the spent catalyst)
of viscous dark orange-reddish oil. It was determined therefore
that this particular spent catalyst contains 0.13% oligomers and
16.7% conjunct polymers. The hydrolysis can also be accomplished
using acidic (aqueous HCl) or basic (aqueous NaOH) solutions.
Example 4
Characterization of Recovered Conjunct Polymer from Deactivated IL
A
[0075] The recovered conjunct polymers according to the procedure
described in Example 3 were characterized by elemental analysis and
by infrared, NMR, GC-Mass and UV and spectroscopy methods. The
recovered conjunct polymers have hydrogen/carbon ratio of 1.76 and
chlorine content of 0.8%. .sup.1H-NMR and .sup.13C-NMR showed the
presence of olefinic protons and olefinic carbons. Infra Red
indicated the presence of olefinic regions and the presence of
cyclic systems and substituted double bonds. GCMS showed the
conjunct polymers to have molecular weights ranging from 150-mid
600 s. The recovered conjunct polymers have boiling ranges of
350-1100.degree. F. as indicated by high boiling simulated
distillation analysis. UV spectroscopy showed a UV .lamda..sub.max
at 250 nm pointing highly conjugated double bonds systems.
Example 5
Hydrogenation of Deactivated IL A Using Al metal and HCl and
Determination of the Amount of Residual Conjunct Polymers
[0076] Saturation of the double bonds of the conjunct polymers
using aluminum metal and HCl was achieved according to the
procedure shown below. To 40 gm of spent ionic liquid containing
15.5 wt % (6.2 gm) of conjunct polymers in 300 cc autoclave, 100 ml
of anhydrous n-hexane and 9 gm of aluminum were added. The
autoclave was sealed (all done in glove box), and 10 gm of
anhydrous HCl were introduced via an inlet. The reaction was
stirred at >1200 rpm and with intent of heating to 75.degree. C.
The reaction was very exothermic and after few minutes the
temperature rose to 81.degree. C. and the pressure to 290 psi.
Then, the pressure and the temperature began to drop. At the end of
the run (1.5 hrs) the temperature was at 75.degree. C. and the
pressure was at 99 psi. The reactor was cooled to room temperature
and the organic phase was decanted off. The ionic liquid phase was
rinsed twice with 50 ml anhydrous hexane. The hexane layers were
combined and concentrated under reduced pressure and heat to remove
the solvent (hexane) giving 5.8 gm (93.5% of the weight of conjunct
polymer originally present in the deactivated ionic liquid.).
Hydrolysis of 10 gm of the treated ionic liquid gave 0.06 gm of
conjunct polymers indicating a total of 4% remained in the ionic
liquid phase. The hydrogenated products showed normal H/C ratios
and NMR, IR and UV spectroscopy all indicated the disappearance of
the double bonds.
Example 6
Determination of Activity of Deactivated IL A Using Batch
Alkylation of isoPentane with Ethylene
[0077] The regenerated catalyst was highly active. The activity of
the regenerated ionic liquid catalyst matched the activity of the
freshly prepared catalyst in the alkylation of ethylene with
isopentane to make C.sub.7s. Table 1 compares the activity of the
regenerated catalyst with the freshly prepared and the spent
catalysts in the alkylation of ethylene with isopentane. The
alkylation of isopentane with ethylene was done according to the
procedure describe below. A 300 cc autoclave was charged with 20 gm
of ionic liquid catalyst, 100 gm anhydrous isopentane, 10 gm
ethylene and 0.3 gm anhydrous HCl. The reaction was then stirred
.about.1200 rpm and heated to 50.degree. C. at autogenic pressures.
The starting pressure was usually 280-320 psi. The reaction was
usually complete when the pressure dropped down to single digits.
In the case of slow going reaction, the reaction was allowed to go
on for 1 hr. At the end of the reaction, the reactor was vented out
and a gas sample was checked by GC for ethylene concentration. The
liquid reaction mixture was allowed to settle into 2 phases. The
organic phase was decanted and analyzed for product distribution by
GC analysis. The following Table 1 draws a comparison among the
freshly made, the spent and the regenerated catalysts.
TABLE-US-00002 TABLE 1 Regenerated. Fresh Catalyst Spent Catalyst
Catalyst Reaction Time 9 min. 60 min. 6 min. Starting 300 psi 286
psi 297 psi Pressure Ending pressure 11 302 psi 7 iC5 72 98% 67 C7s
19 ~1.4% 19 2,3-DM-Pentane 8.23 0.9 9 2,4-DM-Pentane 10 0.6 10
2,3DM/2,4DM 0.82 1.5 0.9
Example 7
Removal of Conjunct Polymer from Deactivated Catalyst A by the
Addition of Pyridine
[0078] Note that a process based on this example would require the
addition of HCl and AlCl.sub.3 in the second regeneration reactor.
In this case, the cation of the ionic liquid is pyridinium
hydrochloride chloride, with H-- instead of butyl-.
[0079] Deactivated Catalyst A (10.022 g) containing 24.6% conjunct
polymers was weighed into a bottle and treated with 2.24 g of
pyridine. After stirring for 45 minutes at ambient temperature, the
contents of the bottle were extracted three times with 6.8 g of
hexane. The hexane extracts were combined and evaporated under a
stream of nitrogen. The net weight of residue was 1.84 grams or
18.4 wt %. The starting spent ionic liquid contained 24.6% conjunct
polymers.
Example 8
Removal of Conjunct Polymer from Deactivated Catalyst a by
1-Butyl-Pyridinium Chloride
[0080] In a round bottom reaction flask equipped with stirring bar
and drying tube (CaCl.sub.2 drying tube) 100 gm of anhydrous hexane
were added to 20 gm of spent butylpyridinium chloroaluminate ionic
liquid catalyst containing 16 wt % (3.2 gm) conjunct polymers. Five
grams of butylpyridinium chloride was added to the 20 gm of spent
catalyst already in 100 ml anhydrous hexane. The reaction was
stirred for 30 min. and the hexane layer was decanted off. The
residue was rinsed with an additional 50 ml hexane. The hexane
layers were added and concentrated to give 1.2 gm of possible 3.2
gm of conjunct polymers. An additional 3 gm of butylpyridinium
chloride and 50 ml anhydrous hexane were added to the ionic liquid
residue from the treatment of the first 5 gm of butylpyridinium
chloride and the mixture was stirred for .about.15-20 minutes. The
reaction mixture turned into two phases. One phase consisted of
granulated brown solids and the hexane layer containing the
remainder of the conjunct polymers. The hexane layer was decanted
off and the remaining solids were rinsed with additional 50 ml
anhydrous hexane. The hexane layers were combined and concentrated
on a rotary evaporator to give additional 1.95 gm of conjunct
polymers (in addition to the 1.2 gm recovered from the first
addition of butylpyridinium chloride). Thus, a total of 3.15 gm or
98.4% of the conjunct polymers present in the spent catalyst were
removed. The above procedure was repeated with similar results
using other spent catalysts with varying conjunct polymers
contents.
[0081] The recovered conjunct polymers removed by the procedure
described above exhibited all the physical and spectroscopic
characteristics of conjunct polymers isolated by hydrolysis
methods.
[0082] The recovered solid were stripped off the solvent (not to
dryness) on a rotary evaporator at 14 torr and 60.degree. C. To the
obtained brown solids, in an Erlenmeyer flask in a glove box, 6.5
gm of AlCl.sub.3 were slowly added while stirring. After al the
AlCl.sub.3 was added, the resulting liquid was allowed to stir for
additional 30 minutes. The liquid was then filtered and used for
alkylation of ethylene with isopentane as a test for the activity
of this partially regenerated ionic liquid catalyst.
Example 9
Determination of the Activity of the Regenerated ButylPyridinium
Chloroaluminate Ionic Liquid Catalyst
[0083] The regenerated butylpyridinium chloroaluminate ionic liquid
catalyst described in Example 8 was tested for activity by using it
as the catalyst in the alkylation of isopentane with ethylene and
comparing it with freshly-made catalyst. The alkylation of
isopentane with ethylene was done according to the following
procedure. A 300 cc autoclave was charged with 20 gm of ionic
liquid catalyst, 100 gm anhydrous isopentane, 10 gm ethylene and
0.3 gm anhydrous HCl. The reaction was then stirred .about.1200 rpm
and heated to 50.degree. C. at autogenic pressures. The starting
pressure was usually 280-320 psi. The reaction was usually complete
when the pressure dropped down to single digits. In the case of
slow going reaction, the reaction was allowed to go on for 1 hr. At
the end of the reaction, the reactor was vented out and a gas
sample was checked by GC for ethylene concentration. The two phase
reaction mixture was allowed to settle into catalyst phase (lower
phase) and the hydrocarbon phase (the upper phase). The hydrocarbon
phase containing the feeds and the alkylation products was decanted
and analyzed for product distribution by GC analysis.
[0084] Table 2 below shows the ethylene/isopentane alkylation
results of this regenerated catalyst compared with the alkylation
results of the fresh and the spent catalyst.
TABLE-US-00003 TABLE 2 Fresh Catalyst Spent Catalyst Regen. Cat.
Reaction Time 9 min. 60 min. 14 min. Starting 300 psi 286 psi 280
psi Pressure Ending pressure 17 302 psi 4 psi iC5 72 98% 69.4% C7s
19 (72%) ~1.4% 20.1% 2,3-DM-Pentane 8.23 (31.5%) 0.9 10.7%
2,4-DM-Pentane 10 (38%) 0.6 8.9% 2,3DM/2,4DM 0.82 1.5 1.2
Alkylation of ethylene with isopentane at iC5/C2.sup.= of 4 @
50.degree. C.
[0085] From the table above, the activity of the regenerated
catalyst is comparable to that of the fresh catalyst. The spent
catalyst containing the conjunct polymers is inactive.
Example 10
Removal of Conjunct Polymers from Deactivated Catalyst A by
Hydrogenation with Palladium on Carbon Catalyst
[0086] In a drybox, 3.0 grams of 10% palladium on carbon (Pd/C)
catalyst was charged to a 100 mL stirred autoclave. Next, .about.30
mL (31.33 g) of Deactivated Catalyst A was added. The autoclave was
taken out of the drybox and charged with 900 psig hydrogen at
ambient temperature. The reactor was heated to 100.degree. C. for
14.75 hours and then cooled. A portion of the recovered catalyst
(22.48 g) was extracted three times with 7 g of dry hexane. The
hexane extracts were combined and evaporated under a stream of
nitrogen to yield 0.408 g of clear, colorless oil. This corresponds
to a recovery of 9.9 wt % of the conjunct polymer originally
present in the Deactivated Catalyst A.
[0087] An 11.26 g sample of hexane-extracted, hydrogenated
Deactivated Catalyst A was weighed into a bottle and hydrolyzed as
described in Example 3. After combining the hexane extracts and
evaporation under a stream of nitrogen, 0.87 g of a non-volatile
residue was recovered. This corresponds to 7.73 wt % conjunct
polymer remaining on the Deactivated Catalyst A after hydrogenation
with 10% Pd/C catalyst. This corresponds to removal of 37.2 wt % of
the conjunct polymer originally present in Deactivated Catalyst A.
The difference between 9.9% hydrogenated conjunct polymer recovered
and 37.2% conjunct polymer removed from Deactivated Catalyst A is
due to losses during hexane evaporation of light components formed
by hydrocracking.
Example 11
Removal of Conjunct Polymer from Deactivated Catalyst B by
Hydrogenation with Palladium on Carbon Catalyst
[0088] The procedure of Example 10 was repeated using Deactivated
Catalyst B (31.33 g). The amount of 10% Pd/C catalyst was 0.10 g.
Hexane, 30 mL, was also added to aid stirring. The initial pressure
at ambient temperature was 900 psig. After heating 18 hours at
100.degree. C. and cooling, the pressure was 650 psig. After
extraction of hexane and evaporation of light components, 0.43 g of
clear, colorless, oil was recovered. This corresponds to a recovery
(as hydrogenated conjunct polymer) of 5.92 wt % of the original
conjunct polymer present in Deactivated Catalyst B.
[0089] A sample of 15.009 g of Deactivated Catalyst B after
hydrogenation and hexane extraction was placed in a bottle and
hydrolyzed as described in Example 3. After hexane extraction and
evaporation of the volatiles from the combined hexane extracts, a
residue of 1.56 g of conjunct polymer was obtained. This
corresponds to conjunct polymers content after hydrogenation of
10.4 wt %. Alternatively, 61.6 wt % of the conjunct polymer
originally present in Deactivated Catalyst B was removed by
hydrogenation.
Example 12
Removal of Conjunct Polymer from Deactivated Catalyst C by
Hydrogenation with Palladium on Alumina Catalyst
[0090] The procedure of Example 10 was repeated using Deactivated
Catalyst C (21.278 g). The hydrogenation catalyst was 1.04 g of 1.0
wt % Pd on Al.sub.2O.sub.3. In this experiment, no hexane was added
to aid stirring. The initial pressure at 100.degree. C. was
.about.1212 psig and after heating 4.5 hours at 100.degree. C., the
pressure was .about.1090 psig. After extraction of hexane and
evaporation of light components, no oil was recovered.
[0091] A sample of 17.33 g of Deactivated Catalyst C after
hydrogenation and hexane extraction was placed in a bottle and
hydrolyzed as described in Example 3. After hexane extraction and
evaporation of the volatiles from the combined hexane extracts, a
residue of 1.49 g of conjunct polymer was obtained. This
corresponds to conjunct polymer content after hydrogenation of 8.60
wt %. Alternatively, 37.4 wt % of the conjunct polymer originally
present in Deactivated Catalyst C was removed by hydrogenation.
Example 13
Removal of Conjunct Polymer from Deactivated Catalyst C by
Hydrogenation with Supported Platinum on Alumina Catalyst
[0092] The procedure of Example 10 was repeated using Deactivated
Catalyst C (20.78 g). The hydrogenation catalyst was 1.46 g of 0.5
wt % Pt on Al.sub.2O.sub.3. In this experiment, no hexane was added
to aid stirring. The initial pressure at 100.degree. C. was
.about.1250 psig and after heating 4.5 hours at 100.degree. C., the
pressure was .about.1190 psig. After extraction of hexane and
evaporation of light components, no oil was recovered.
[0093] A sample of 17.55 g of Deactivated Catalyst C after
hydrogenation and hexane extraction was placed in a bottle and
hydrolyzed as described in Example 3. After hexane extraction and
evaporation of the volatiles from the combined hexane extracts, a
residue of 2.18 g of conjunct polymer was obtained. This
corresponds to a conjunct polymer content after hydrogenation of
12.4 wt %. Alternatively, 9.7 wt % of the conjunct polymer
originally present in Deactivated Catalyst C was removed by
hydrogenation.
Example 14
Removal of Conjunct Polymer from Deactivated Catalyst C by
Hydrogenation with Supported Ni Catalyst
[0094] The procedure of Example 10 was repeated using Deactivated
Catalyst C (19.20 g). The hydrogenation catalyst was 1.02 g of Ni
on synthetic mica montmorillonite. The hydrogenation catalyst had
been previously reduced in flowing hydrogen at ambient pressure and
at 450.degree. C. In this experiment, no hexane was added to aid
stirring. The initial pressure at 100.degree. C. was .about.1250
psig and after heating 4 hours at 100.degree. C., the pressure was
.about.1200 psig. After extraction of hexane and evaporation of
light components, no oil was recovered.
[0095] A sample of 15.76 g of Deactivated Catalyst C after
hydrogenation and hexane extraction was placed in a bottle and
hydrolyzed as described in Example 3. After hexane extraction and
evaporation of the volatiles from the combined hexane extracts, a
residue of 1.82 g of conjunct polymer was obtained. This
corresponds to conjunct polymer content after hydrogenation of 11.6
wt %. Alternatively, 16.0 wt % of the conjunct polymer originally
present in Deactivated Catalyst C was removed by hydrogenation.
Example 15
Removal of Conjunct Polymer from Deactivated Catalyst A by
Hydrogenation over Ni--Al Alloy
[0096] As a way for regenerating deactivated chloroaluminate ionic
liquids, 35 gm of spent ionic liquids containing 22.3 wt % (7.8 gm)
conjunct polymers in a 300 cc autoclave, 2 gm of Ni--Al alloy and
70 ml of anhydrous hexane were added. The autoclave was sealed and
pressurized with hydrogen to 500 psi and heated to 100.degree. C.
while stirring at >1200 rpm for .about.1.5 hrs. The starting
pressure was 500 psig at room temperature. As the autoclave heated
up, the pressure rose to 620 psig. As the reaction continued,
pressure dropped to 560 psig and remained at that pressure for the
remainder of the reaction time. The reactor was cooled down and to
the contents allowed to settle. The resultant reaction mixture
contained the hexane layer (the top layer), the ionic liquid layer
(the bottom layer) and the Ni--Al alloy settled to the bottom of
the reactor. The hexane layer was decanted off and saved. The ionic
liquid layer was rinsed 3.times.50 ml anhydrous hexane. The hexane
from the reaction and all hexane rinses were combined and dried
over MgSO4. Filtration and concentration of the hexane under
reduced pressure (.about.24 torr) in a hot water bath
(.about.75.degree. C.) gave 6.9 gm of slightly faint yellow oil
(88.5% of the expected saturated conjunct polymers). The total
conjunct polymers removed by hydrogenation over Ni--Al at
100.degree. C. and 500 psi H.sub.2 pressure was 94%.
Example 16
[0097] Example 15 above was repeated with 50 gm of spent ionic
liquid containing 24.3 wt % (12.15 gm) conjunct polymers in 70 cc
hexane in the presence of 3 gm of Ni--Al alloy at 100.degree. C.
and starting hydrogen pressure of 500 psi. The reaction ran for 1.5
hrs. A total of 11.5 gm (94.6%) conjunct polymers were removed from
the spent catalyst based on obtained saturated polymers and
recovered CPs from the hydrolysis of 10 gm portion of the treated
ionic liquid catalyst. The remainder of the treated ionic liquid
catalyst was saved and tested for activity as described in example
12.
Example 17
Hydrogenation of Conjunct Polymers in Spent Chloroaluminate Ionic
Liquid Catalyst Over Nickel Metal
[0098] As in Example 15 above, 25 gm of spent chloroaluminate ionic
liquid catalyst containing 15.5 wt % (3.87 gm) conjunct polymers in
60 ml anhydrous hexane (in 300 cc autoclave) was hydrogenated at
100.degree. C. and 500 psi hydrogen pressure over Nickel metal (3
gm) for 1.5 hours. Once the heating started, the pressure steadily
started rising until it reached 946 psi at 100.degree. C. The
pressure dropped slightly to 910 psi at the end of the run. The
reaction was stopped and the organic phase containing the
hydrogenated polymers was decanted off. The ionic liquid-Ni residue
was rinsed with 2.times.50 ml anhydrous hexane. All the organic
layers were combined and dried over MgSO4. Filtration and
concentration to remove hexane gave 1.58 gm (41%) of the
hydrogenated polymers as colorless oil. The ionic liquid catalyst
was separated from Nickel metal by filtration. The ionic liquid
catalyst was entirely hydrolyzed giving 1.62 gm conjunct polymers
(the total amount of CPs remaining in the catalyst). This indicates
that hydrogenation over Nickel metal led to the overall removal of
2.2 gm (58%) of the conjunct polymers from the spent catalyst.
Example 18
Determination of the Activity of the Regenerated ButylPyridinium
Chloroaluminate Ionic Liquid Catalyst by Hydrogenation Over Ni--Al
Alloy
[0099] The regenerated butylpyridinium chloroaluminate ionic liquid
catalyst described in Examples 15 and 16 was tested for activity by
using it as the catalyst in the alkylation of isopentane with
ethylene and comparing it with freshly-made catalyst. The
alkylation of isopentane with ethylene was done according to the
following procedure A 300 cc autoclave was charged with 20 gm of
ionic liquid catalyst, 100 gm anhydrous isopentane, 10 gm ethylene
and 0.3 gm anhydrous HCl. The reaction was then stirred .about.1200
rpm and heated to 50.degree. C. at autogenic pressures. The
starting pressure was usually 280-320 psi. The reaction was usually
complete when the pressure dropped down to single digits. In the
case of slow going reaction, the reaction was allowed to go on for
1 hr. At the end of the reaction, the reactor was vented out and a
gas sample was checked by GC for ethylene concentration. The liquid
reaction mixture was allowed to settle into 2 phases. The organic
phase was decanted and analyzed for product distribution by GC
analysis. The following Table 3 draws a comparison among the
freshly made, the spent and the regenerated catalysts.
TABLE-US-00004 TABLE 3 Fresh Ionic Spent Ionic Ni--Al Regen. Liquid
Catalyst Liquid Catalyst Ionic Liquid Cat. Reaction Time 6-9 min.
60 min. 4-7 min. Starting 300 psi 286 psi 350 psi Pressure Ending
pressure 11 302 psi 7 iC5 wt % 72 98 61 C7s wt %: 2,3-DM-Pentane
8.23 0.9 8.5 2,4-DM-Pentane 10 0.6 11.3 Other C7s 0.77 0.1 1.2
2,3DM/2,4DM 0.82 1.5 0.75
Example 19
Removal of Conjunct Polymer from Deactivated IL A by Reaction with
Isobutane
[0100] Deactivated IL A (14.50 gm) containing .about.18 wt %
conjunct polymer was charged to a nitrogen-filled 100 mL autoclave.
Ten milliliters of HCl gas measured at ambient temperature and
pressure were added to the autoclave. The autoclave was then filled
with liquid isobutane (81.6 gm) at ambient temperature.
[0101] The autoclave was heated to 100 C with stirring for 5 hours,
then cooled to ambient temperature. In a drybox, the ionic liquid
was removed and extracted with hexane to remove saturated conjunct
polymer.
[0102] To measure the removal of conjunct polymer, 7.56 grams of
the recovered ionic liquid were hydrolyzed. The resulting aqueous
mixture was extracted with hexane. After evaporation of hexane,
0.60 grams remained, indicating that after reaction with isobutane
and HCl, the ionic liquid contained 7.9 wt % conjunct polymer. This
means that the treatment with isobutane and HCl removed .about.57%
of the conjunct polymer originally present in the used ionic liquid
catalyst.
[0103] There are numerous variations on the present invention which
are possible in light of the teachings and supporting examples
described herein. It is therefore understood that within the scope
of the following claims, the invention may be practiced otherwise
than as specifically described or exemplified herein.
* * * * *