U.S. patent application number 11/222034 was filed with the patent office on 2006-04-06 for process for separating oxygen-containing compounds contained in a hydrocarbon feed, employing an ionic liquid.
Invention is credited to Adeline Biard, Helene Olivier-Bourbigou, Christophe Vallee.
Application Number | 20060070919 11/222034 |
Document ID | / |
Family ID | 34950858 |
Filed Date | 2006-04-06 |
United States Patent
Application |
20060070919 |
Kind Code |
A1 |
Vallee; Christophe ; et
al. |
April 6, 2006 |
Process for separating oxygen-containing compounds contained in a
hydrocarbon feed, employing an ionic liquid
Abstract
In order to separate oxygen-containing compounds contained in a
hydrocarbon feed containing 1 to 100 carbon atoms and having any
distribution of chemical categories, a process is carried out in
which: said hydrocarbon feed is brought into contact with an
extraction phase which contains at least one non-aqueous ionic
liquid with general formula Q.sup.+A.sup.-, the proportion of ionic
liquid in the extraction phase representing at least 25% by weight;
the extraction effluent is separated into said extraction phase
which contains at least one ionic liquid and at least all or a
portion of the oxygen-containing compounds initially present in the
hydrocarbon feed, and into the hydrocarbon feed which is depleted
in oxygen-containing compounds.
Inventors: |
Vallee; Christophe;
(Villeurbanne, FR) ; Biard; Adeline;
(Villeurbanne, FR) ; Olivier-Bourbigou; Helene;
(Saint Genis Laval, FR) |
Correspondence
Address: |
MILLEN, WHITE, ZELANO & BRANIGAN, P.C.
2200 CLARENDON BLVD.
SUITE 1400
ARLINGTON
VA
22201
US
|
Family ID: |
34950858 |
Appl. No.: |
11/222034 |
Filed: |
September 9, 2005 |
Current U.S.
Class: |
208/298 ;
208/289; 208/292; 208/293 |
Current CPC
Class: |
C10G 21/27 20130101;
B01D 11/0492 20130101 |
Class at
Publication: |
208/298 ;
208/289; 208/292; 208/293 |
International
Class: |
C10G 29/00 20060101
C10G029/00; C10G 21/00 20060101 C10G021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 10, 2004 |
FR |
04/09.660 |
Claims
1. A process for separating oxygen-containing compounds contained
in a hydrocarbon feed containing 1 to 100 carbon atoms, and with
any chemical category distribution, said process being
characterized in that: said hydrocarbon feed containing
oxygen-containing compounds (Cox) is brought into contact in a
contacter (A) with an extraction phase (Pex) which contains at
least one non-aqueous ionic liquid with general formula
Q.sup.+A.sup.-, the proportion of ionic liquid in the extraction
phase representing at least 25% by weight; the effluent from the
unit (A) is separated in a decanting unit (B) into said extraction
phase which contains at least one ionic liquid and at least all or
a portion of the oxygen-containing compounds initially present in
the hydrocarbon feed, and into the hydrocarbon feed depleted in
oxygen-containing compounds (Cpur).
2. A process according to claim 1, in which the effluent from the
decanting unit (B) is introduced into the separation unit (C) from
which the extraction phase containing at least one ionic liquid and
a minor portion of the oxygen-containing compounds, and the major
portion of the oxygen-containing compounds (Cext) are
separated.
3. A process according to claim 1, in which the extraction phase
from the separation unit (C) is reintroduced into the contacter (A)
with the hydrocarbon feed to be treated.
4. A process according to claim 1, characterized in that in the
non-aqueous ionic liquid with formula Q.sup.+A.sup.-, the anions
A.sup.- are selected from halides, nitrate, sulphate,
alkylsulphates, phosphate, alkylphosphates, acetate,
halogenoacetates, tetrafluoroborate, tetrachloroborate,
hexafluorophosphate. trifluoro-tris-(pentafluoroethyl)phosphate,
hexafluoroantimonate, fluorosulphonate, alkyl sulphonates,
perfluoroalkylsulphonates, bis(perfluoroalkylsulphonyl)amides,
tris-trifluoromethylsulphonyl methylide with formula
C(CF.sub.3SO.sub.2).sub.3.sup.-, bis-trifluoromethylsulphonyl
methylide with formula HC(CF.sub.3SO.sub.2).sub.3.sup.-,
arenesulphonates, optionally substituted with halogen or
halogenalkyl groups, the tetraphenylborate anion and
tetraphenylhorate anions the aromatic rings of which are
substituted, tetra-(trifluoroacetoxy)-borate, bis-(oxalato)-borate,
dicyanamide, tricyanomethylide, and the tetrachloroaluminate
anion.
5. A process according to claim 1, characterized in that cation
Q.sup.+ is selected from quaternary phosphonium, ammonium,
guanidinium and/or sulphonium cations.
6. A process according to claim 5, characterized in that quaternary
ammonium and/or phosphonium cation Q.sup.+ has one of general
formulae NR.sup.1R.sup.2R.sup.3R.sup.4+ and
PR.sup.1R.sup.2R.sup.3R.sup.4+ or one of general formulae
R.sup.1R.sup.2N.dbd.CR.sup.3R.sup.4+ and R.sup.1R.sup.2P.dbd.C
R.sup.3R.sup.4+ in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4,
which may be identical or different, each represent hydrogen of a
hydrocarbyl residue containing 1 to 30 carbon atoms.
7. A process according to claim 6, characterized in that R.sup.1,
R.sup.2, R.sup.3 and R.sup.4 each represent an alkyl group, a
saturated or non saturated group, a cycloalkyl or aromatic group or
an aryl or aralkyl group, which may be substituted.
8. A process according to claim 6, characterized in that at least
one of groups R.sup.1, R.sup.2, R.sup.3 and R.sup.4 carries one or
more functions selected from the following: --CO.sub.2R, --C(O)R,
--OR, --C(O)NRR', --C(O)N(R)NR'R'', --NRR', --SR, --S(O)R,
-S(O).sub.2R, --SO.sub.3R, --CN, --N(R)P(O)R'R', in which R, R' and
R'', which may be identical or different, each represent hydrogen
or hydrocarbyl radicals containing 1 to 30 carbon atoms.
9. A process according to claim 5, characterized in that the
ammonium and/or phosphonium ion is derived from a
nitrogen-containing and/or phosphorus-containing heterocycles
comprising 1, 2 or 3 nitrogen and/or phosphorus atoms, with general
formulae ##STR2## in which the cycles are constituted by 4 to 10
atoms, preferably 5 to 6 atoms, and R.sup.1 and R.sup.2, which may
be identical or different, are as defined above.
10. A process according to claim 5, characterized in that the
quaternary ammonium or phosphonium cation has one of the following
formulae:
R.sup.1R.sup.2+N.dbd.CR.sup.3--R.sup.7--R.sup.3C.dbd.N.sup.+R.sup.1R.sup.-
2 and
R.sup.1R.sup.2+P.dbd.CR.sup.3--R.sup.7--R.sup.3C.dbd.P.sup.+R.sup.1R-
.sup.2 in which R.sup.1, R.sup.2 and R.sup.3, which may be
identical or different, are as defined above and R.sup.7 represents
an alkylene or phenylene residue.
11. A process according to claim 6, characterized in that the
groups R.sup.1, R.sup.2, R.sup.3 and R.sup.4 represent methyl,
ethyl, propyl, isopropyl, butyl, secondary butyl, tertiary butyl,
amyl, phenyl, benzyl or 2-hydroxyethyl radicals and R.sup.7
represents a methylene, ethylene, propylene or phenylene group.
12. A process according to claim 5, characterized in that the
quaternary ammonium and/or phosphonium cation Q.sup.+ is selected
from the group formed by N-butylpyridinium, N-ethylpyridinium,
pyridinium, 3-ethyl-1-methylimidazolium,
3-butyl-1-methylimidazolium, 3-hexyl-1-methylimidazolium,
3-butyl-1,2-dimethylimidazolium, the
1-(2-hydroxyethyl)-3-methylinidazolium cation, the
1-(2-carboxyethyl)-3-methylimidazolium cation, diethylpyrazolium,
N-butyl-N-methylpyrrolidinium, N-butyl-N-methylmorpholinium,
trimethylphenylammonium, tetrabutylphosphonium and
tributyl-tetradecylphosphonium.
13. A process according to claim 5, characterized in that the
quaternary sulphonium and/or quaternary guanidinium cations have
one of the following general formulae: SR.sup.1R.sup.2R.sup.3+ or
C(NR.sup.1R.sup.2)(NR.sup.3R.sup.4)(NR.sup.5R.sup.6).sup.+ in which
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6, which may
be identical or different, each representing hydrogen or a
hydrocarbyl residue containing 1 to 30 carbon atoms.
14. A process according to claim 13, characterized in that R.sup.1,
R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 each represent an
alkyl group, a saturated or non saturated group, a cycloalkyl or
aromatic group or an aryl or aralkyl group, which may be
substituted.
15. A process according to claim 13, characterized in that at least
one of groups R.sup.1, R.sup.2, R.sup.3 and R.sup.4 carries
hydrocarbyl radicals carrying one or more functions selected from
the following: --CO.sub.2R, --C(O)R, --OR, --C(O)NRR',
--C(O)N(R)NR'R'', --NR'R'', --SR, --S(O)R, --S(O).sub.2R,
--SO.sub.3R, --CN, --N(R)P(O)R'R', --PRR', --P(O)RR', --P(OR)(OR'),
P(O)(OR)(OR'), in which R, R' and R'', which may be identical or
different, each represent hydrogen or hydrocarbyl radicals
containing 1 to 30 carbon atoms.
16. A process according to claim 1, characterized in that the
non-aqueous ionic liquid is 3-butyl-1-methylimidazolium
bis(trifluoromethylsulphonyl)amide, 3-butyl-1,2-dimethylimidazolium
bis(trifluoromethylsulphonyl)amide, N-butyl-N-methylpyrrolidinium
bis(trifluoromethylsulphonyl)amide, 3-butyl-1-methylimidazolium
tetrafluoroborate, 3-butyl-1,2-dimethylimidazolium
tetrafluoroborate, 3-ethyl-1-methylimidazolium tetrafluoroborate,
3-butyl-1-methylimidazolium hexafluoroantimonate,
3-butyl-1-methylimidazolium trifluoroacetate,
3-ethyl-1-methylimidazolium triflate,
1-(2-hydroxyethyl)-3-methylimidazolium
bis(trifluoromethylsulphonyl)amide,
1-(2-carboxyethyl)-3-methylimidazolium
bis(trifluoromethylsulphonyl)amide, and
N-butyl-N-methylmorpholinium
bis(trifluoromethylsulphonyl)amide.
17. A process for separating oxygen-containing compounds contained
in a hydrocarbon feed according to claim 1, in which the contacter
(A) and the decanting unit (B) are combined in a single piece of
equipment.
18. A process according to claim 1 comprising separating
oxygen-containing compounds contained in a hydrocarbon cut composed
mainly of olefins and paraffins.
19. A process according to claim 18 comprising separating
oxygen-containing compounds contained in a hydrocarbon cut
containing 0 to 50% by weight of olefins and 50% to 100% by weight
of paraffins.
20. A process according to claim 1 comprising separating
oxygen-containing compounds contained in Fischer-Tropsch synthesis
effulents, said oxygen-containing compounds containing 1 to 50
carbon atoms.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of purifying
hydrocarbon feeds. In particular, the present invention relates to
separating oxygen-containing compounds contained in a hydrocarbon
cut. The present invention is of particular application in
separating alcohols and acids contained in a hydrocarbon cut mainly
composed of paraffins and olefins. More particularly still, the
present invention is highly suitable to separating alcohols and
acids contained in an effluent from the Fischer-Tropsch
reactor.
[0002] Separating oxygen-containing compounds contained in
effluents from the Fischer-Tropsch reactor is necessary as said
oxygen-containing compounds inhibit or reduce the activity of
catalysts used for treating and upgrading such cuts.
[0003] The present invention concerns a process for separating
oxygen-containing compounds contained in any hydrocarbon cut using
ionic liquids. More particularly, the invention is applicable to
the treatment of effluents from the Fischer-Tropsch synthesis.
PRIOR ART
[0004] In the Fischer-Tropsch process, synthesis gas (mixture of
CO+H.sub.2) is catalytically transformed into oxygen-containing
products and into essentially linear hydrocarbons, the length of
the carbon chain possibly being from 1 to more than 100.
[0005] Said Fischer-Tropsch synthesis effluents are generally free
of heteroatomic impurities such as sulphur, nitrogen or metals.
They also contain few or practically no aromatics, naphthenes and
more generally cyclic compounds, in particular in the case of a
cobalt catalyst.
[0006] In contrast, such effluents may contain a non negligible
amount of oxygen-containing products which, expressed as a
percentage by weight, is generally less than 20% in total, and also
an amount of unsaturated compounds (generally olefinic compounds)
which is generally less than 50% by weight.
[0007] In the case of effluents from the Fischer-Tropsch synthesis,
the oxygen-containing compounds are more particularly alcohols and
acids.
[0008] Chemical conversion of synthesis gas into hydrocarbons using
the Fischer-Tropsch process, commonly known as the Fischer-Tropsch
synthesis, is carried out in the presence of a catalyst based on at
least one group VIII metal.
[0009] The catalysts used may be of different natures, but usually
contain bulk or supported iron or cobalt.
[0010] The supports used are generally based on silica, alumina or
titanium oxide.
[0011] The Fischer-Tropsch synthesis is generally operated at
temperatures in the range 200.degree. C. to 300.degree. C., and at
pressures in the range 1 MPa to 8 MPa.
[0012] Using a Fe/Mn/Zn catalyst at a pressure of 3 to 6 MPa can
result in high selectivities for olefins and oxygen-containing
compounds (principally alcohols) with a chain length of 2 to more
than 30. The invention is thus particularly suitable for the
treatment of that type of Fischer-Tropsch synthesis effluents.
[0013] U.S. Pat. No. 4,686,317 discloses a process for eliminating
oxygen-containing impurities contained in a light hydrocarbon cut
(C.sub.2 to C.sub.9). It comprises extracting oxygen-containing
compounds using a heavy polar organic solvent, washing the
hydrocarbons with water to recover the dissolved solvent, and
mixing the phase derived from the extraction and the wash water to
recover the heavy polar organic solvent. That process does not
consider recovering the extracted oxygen-containing compounds.
[0014] US-A-2004/0044263 discloses a process for separating
oxygen-containing compounds from a hydrocarbon mixture containing
paraffins, olefins and oxygen-containing compounds. It uses
liquid-liquid extraction with a polar solvent and an apolar organic
counter-solvent. However, that process suffers from a number of
disadvantages. Firstly, it is limited to C.sub.8 and higher
hydrocarbons and to C.sub.4 and higher alcohols, and secondly, it
necessitates separating the olefins and paraffins from the apolar
organic solvent by distillation.
[0015] The present invention concerns a process for separating
oxygen-containing compounds contained in any hydrocarbon cut (in
particular a cut which may contain hydrocarbons containing less
than 8 carbon atoms, and alcohols containing less than 4 carbon
atoms) using ionic liquids.
[0016] Non-aqueous ionic liquids with general formula
Q.sup.+A.sup.-, initially developed by electrochemists, are now
being used ever more widely as solvents and catalysts for catalytic
or enzymatic organic reactions, as solvents for liquid-liquid
separations, or for the synthesis of novel materials (see, for
example, H Olivier-Bourbigou, L Magna, J Mol Catal A, Chem 2002,
vol 182, p 419).
[0017] The popularity of that novel class of solvents is due to
their physico-chemical properties in that they can be modulated by
changing the nature of the anion and the cation and their very low
vapour tension, to produce alternative solvents which are better
for the environment than conventional volatile organic
solvents.
[0018] Because of their completely ionic nature and their polar
nature, such ionic liquids have proved to be very good solvents for
ionic or polar compounds, a property which in particular allows
easy separation of oxygen-containing compounds from hydrocarbon
cuts.
[0019] US-A-2003/0125599 uses ionic liquids to separate the olefins
contained in a mixture of non olefinic compounds such as paraffins,
aromatics or oxygen-containing compounds. However, this technique
requires a metal salt in addition to an ionic liquid, for example a
copper or silver salt. Further, that technique cannot separate
alcohols from an olefin-paraffin mixture.
[0020] WO-A-02/074718 describes the use of ionic liquids as third
parties (also known as entrainers) for the separation of azeotropic
mixtures or compounds with similar boiling points. However, that
extractive distillation method requires a temperature equal to or
above the boiling point of the most volatile compound, which leads
to a high energy cost. Further, it is not applicable to separating
alcohols contained in a hydrocarbon feed as it is essentially based
on separation as a function of boiling point.
[0021] WO-A-03/070667 concerns a process for liquid-liquid
extraction using ionic liquids, but does not describe the
separation of oxygen-containing compounds contained in a mixture of
hydrocarbons.
BRIEF DESCRIPTION OF THE FIGURE
[0022] FIG. 1 shows a flow diagram of the process of the invention
in which the optional unit (C) is shown in dotted lines.
[0023] Units (A) and (B) may be distinct or combined.
BRIEF DESCRIPTION OF THE INVENTION
[0024] The invention concerns a process for separating
oxygen-containing compounds contained in any hydrocarbon feed,
which uses an extraction phase containing at least one ionic
liquid. The term "any" means that the hydrocarbon feed may contain
1 to 100 carbon atoms with a distribution of chemical categories
(paraffins, olefins, acetylenes, naphthenes and aromatics) which
may itself be of any type (i.e. each chemical family may represent
any percentage in the mixture).
[0025] The term "extraction phase" means the phase containing at
least one ionic liquid which, at the end of the extraction process,
will recover all or a portion of the oxygen-containing compounds
initially present in the hydrocarbon feed.
[0026] Oxygen-containing compounds which may generally be
encountered in a hydrocarbon feed are alcohols, ethers, aldehydes
or ketones, acetals, acids or esters, water or a mixture of these
compounds.
[0027] In the case of Fischer-Tropsch synthesis effluents, said
oxygen-containing compounds are more particularly alcohols and
acids.
[0028] Within the context of the invention, the oxygen-containing
compounds will contain 1 to 100 carbon atoms, preferably 1 to 50
carbon atoms, and more preferably 1 to 20 carbon atoms.
[0029] The separation process of the present invention may briefly
be described in connection with FIG. 1 as follows: [0030] the
hydrocarbon feed containing oxygen-containing compounds (Cox) is
brought into contact in a contacting unit (or contacter) (A) with
an extraction phase (Pex) which contains at least one non-aqueous
ionic liquid with general formula Q.sup.+A.sup.-, the proportion of
ionic liquid in the extraction phase representing at least 25% by
weight; [0031] the effluent from the unit (A) is separated in a
decanting unit (B) into said extraction phase, which contains at
least one ionic liquid and: at least all or a portion of the
oxygen-containing compounds initially present in the hydrocarbon
feed, and into the hydrocarbon feed depleted in oxygen-containing
compounds (Cpur).
[0032] In a variation of the process of the invention, said
extraction phase from the decanting unit (B) may be introduced into
the separation unit (C) from which the extraction phase containing
at least one ionic liquid and a minor portion of the
oxygen-containing compounds, and the major portion of the
oxygen-containing compounds (Cext) are separated.
[0033] In a further variation of the process of the invention, the
extraction phase from the separation unit (C) may be reintroduced
into the contacter (A) with the hydrocarbon feed to be treated.
[0034] Finally, in a further variation of the process of the
invention, the contacter unit (A) and the decanting unit (B) may be
combined in a single piece of equipment, for example in a
liquid-liquid extraction column operating in counter-current
mode.
[0035] The process of the invention is applicable to separating
oxygen-containing compounds contained in a hydrocarbon cut
primarily composed of olefins and paraffins. More particularly, it
may be applicable to separating oxygen-containing compounds
contained in a hydrocarbon cut containing 0 to 50% by weight of
olefins and 50% to 100% by weight of paraffins.
[0036] Finally, the process of the invention is particularly
suitable for separating oxygen-containing compounds contained in
Fischer-Tropsch synthesis effluents, said oxygen-containing
compounds containing 1 to 100 carbon atoms, preferably 1 to 50
carbon atoms, and more preferably 1 to 20 carbon atoms.
DETAILED DESCRIPTION OF THE INVENTION
[0037] The present invention provides a process for separating
oxygen-containing compounds contained in any hydrocarbon feed, said
process being characterized in that: [0038] said hydrocarbon feed
containing oxygen-containing compounds is brought into contact with
an extraction phase which contains at least one non-aqueous ionic
liquid with general formula Q.sup.+A.sup.-, the proportion of ionic
liquid in the extraction phase representing at least 25% by weight;
and [0039] in that said extraction phase, which contains at least
one ionic liquid and at least all or a portion of the
oxygen-containing compounds initially present in the hydrocarbon
feed, is separated from the hydrocarbon feed depleted in
oxygen-containing compounds.
[0040] In a variation of the present invention, the extraction
phase, which contains at least one ionic liquid and all or a
portion of the oxygen-containing compounds initially present in the
hydrocarbon feed, may be regenerated.
[0041] In this case, said extraction phase is eliminated at least
partially from the oxygen-containing compounds it contains and said
extraction phase is re-used by bringing it again into contact with
the hydrocarbon feed. Further, all or part-of the oxygen-containing
compounds contained in the extraction phase may be recovered.
[0042] One of the aims of the present invention is to reduce the
amount of oxygen-containing compounds in a hydrocarbon feed which
may comprise all chemical categories: paraffins, olefins,
acetylenes, naphthenes and aromatics in any proportions.
[0043] The present invention is particularly advantageous when the
hydrocarbon feed comprises at least some olefins, as said olefins
are not modified during said process.
[0044] The separation process of the invention does not cause any
olefin isomerization, in particular no isomerization of alpha
olefins to internal olefins.
[0045] The present invention is particularly advantageous when the
hydrocarbon feed is constituted at least in part by olefins and
paraffins, as the proportion of olefins with respect to the
paraffins is not significantly modified.
[0046] The present invention is also particularly advantageous in
that, because of the non volatile nature of ionic liquids, it is
very easy to recover the oxygen-containing compounds extracted by
distillation or stripping the extraction phase. This point
constitutes a distinct advantage over processes in which the
solvent has to be recovered by expensive distillation.
[0047] In the non-aqueous ionic liquid with formula
Q.sup.+A.sup.-employed in the extraction phase, the anions A.sup.-
are preferably selected from halides, nitrate, sulphate,
alkylsulphates, phosphate, alkylphosphates, acetate,
halogenoacetates, tetrafluoroborate, tetrachloroborate,
hexafluorophosphate, trifluoro-tris-(pentafluoroethyl)phosphate,
hexafluoroantimonate, fluorosulphonate, alkyl sulphonates (for
example methylsulphonate), perfluoroalkylsulphonates (for example
trifluoromethylsulphonate), bis(perfluoroalkylsulphonyl)amides (for
example bis-trifluoromethylsulphonyl amide with formula
N(CF.sub.3SO.sub.2).sub.2.sup.-), tris-trifluoromethylsulphonyl
methylide with formula C(CF.sub.3SO.sub.2).sub.3.sup.-,
bis-trifluoromethylsulphonyl methylide with formula
HC(CF.sub.3SO.sub.2).sub.3.sup.-, arenesulphonates, optionally
substituted with halogens or halogenalkyl groups, the
tetraphenylborate anion and tetraphenylborate anions the aromatic
rings of which are substituted, tetra-(trifluoroacetoxy)-borate,
bis-(oxalato)-borate, dicyanamide, tricyanomethylide, and the
tetrachloroaluminate anion.
[0048] Cations Q.sup.+ are preferably selected from the group
formed by quaternary phosphonium, quaternary ammonium, quaternary
guanidinium and/or quaternary sulphonium. In the formulae below,
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 represent
hydrogen (with the exception of the NH.sub.4.sup.+ cation
NR.sup.1R.sup.2R.sup.3R.sup.4), preferably a single substituent
representing hydrogen, or hydrocarbyl radicals containing 1 to 30
carbon atoms, for example alkyl groups, saturates or unsaturates,
cycloalkyls or aromatics, aryls or aralkyls, which may be
substituted, containing 1 to 30 carbon atoms.
[0049] R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R6 may also
represent hydrocarbyl radicals carrying one or more functions
selected from the following: --CO.sub.2R, --C(O)R, --OR,
--C(O)NRR', --C(O)N(R)NR'R'', --NRR', --SR, --S(O)R, --S(O).sub.2R,
--SO.sub.3R, --CN, --N(R)P(O)R'R', --PRR', --P(O)RR', --P(OR)(OR'),
--P(O)(OR)(OR') in which R, R' and R'', which may be identical or
different, each represent hydrogen or hydrocarbyl radicals
containing 1 to 30 carbon atoms.
[0050] The quaternary sulphonium and quaternary guanidinium cations
preferably have one of the following general formulae:
SR.sup.1R.sup.2R.sup.3+ or
C(NR.sup.1R.sup.2)(NR.sup.3R.sup.4)(NR.sup.5R.sup.6).sup.+ in which
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6, which may
be identical or different, are as defined above.
[0051] The quaternary ammonium and/or phosphonium ions Q.sup.+
preferably have one of general formulae
NR.sup.1R.sup.2R.sup.3R.sup.4+ and PR.sup.1R.sup.2R.sup.3R.sup.4+
or one of general formulae R.sup.1R.sup.2N.dbd.CR.sup.3R.sup.4+ and
R.sup.1R.sup.2P.dbd.CR.sup.3R.sup.4+ in which R.sup.1, R.sup.2,
R.sup.3 and R.sup.4, which may be identical or different, are as
defined above.
[0052] The ammonium and/or phosphonium cations may also be derived
from nitrogen-containing and/or phosphorus-containing heterocycles
comprising 1, 2 or 3 nitrogen and/or phosphorus atoms, with general
formulae: ##STR1## in which the cycles are constituted by 4 to 10
atoms, preferably 5 to 6 atoms, R.sup.1 and R.sup.2, which may be
identical or different, being as defined above.
[0053] The quaternary ammonium or phosphonium cation may also have
one of the following formulae:
R.sup.1R.sup.2+N.dbd.CR.sup.3--R.sup.7--R.sup.3C.dbd.N.sup.+R.sup.1R.sup.-
2 and
R.sup.1R.sup.2+P.dbd.CR.sup.3--R.sup.7--R.sup.3C.dbd.P.sup.+R.sup.1R-
.sup.2 in which R.sup.1, R.sup.2 and R.sup.3, which may be
identical or different, are defined as above and R.sup.7 represents
an alkylene or phenylene radical.
[0054] Particular groups R.sup.1, R.sup.2, R.sup.3 and R.sup.4
which may be mentioned are methyl, ethyl, propyl, isopropyl,
primary butyl, secondary butyl, tertiary butyl, amyl, phenyl or
benzyl radicals; R.sup.7 may be a methylene, ethylene, propylene or
phenylene group.
[0055] Preferably, the ammonium and/or phosphonium cation Q.sup.+
is preferably selected from the group formed by N-butylpyridiniun,
N-ethylpyridinium, pyridinium, 3-ethyl-1-methylimidazolium,
3-butyl-1-methylimidazolium, 3-hexyl-1-methylimidazolium,
3-butyl-1,2-dimethylimidazolium, the
1-(2-hydroxyethyl)-3-methylimidazolium cation, the
1-(2-carboxyethyl)-3-methylimidazolium cation, diethylpyrazolium,
N-butyl-N-methylpyrrolidinium, N-butyl-N-methylmorpholinium,
trimethylphenylammonium, tetrabutylphosphonium and
tributyl-tetradecylphosphonium.
[0056] Examples of salts which may be used in the invention that
can be cited are 3-butyl-1-methylimidazolium
bis(trifluoromethylsulphonyl)amide, 3-butyl-1,2-dimethylimidazolium
bis(trifluoromethylsulphonyl)amide, N-butyl-N-methylpyrrolidinium
bis(trifluoromethylsulphonyl)amide, 3-butyl-1-methylimidazolium
tetrafluoroborate, 3-butyl-1,2-dimethylimidazolium
tetrafluoroborate, 3-ethyl-1-methylimidazolium tetrafluoroborate,
3-butyl-1-methylimidazolium hexafluoroantimonate,
3-butyl-1-methylimidazolium trifluoroacetate,
3-ethyl-1-methylimidazolium triflate,
1-(2-hydroxyethyl)-3-methylimidazolium
bis(trifluoromethylsulphonyl)amide,
1-(2-carboxyethyl)-3-methylimidazolium
bis(trifluoromethylsulphonyl)amide, and
N-butyl-N-methylmorpholinium bis(trifluoromethylsulphonyl)amide.
These salts may be used alone or as a mixture.
[0057] In the present invention, the proportion of ionic liquid
with formula Q.sup.+A.sup.- in the extraction phase represents at
least 25% by weight.
[0058] The extraction phase may also contain ionic liquid(s), one
or more polar organic solvents with a relative dielectric constant
of more than 5, or organic compounds contained in the hydrocarbon
feed and partially or completely soluble in the ionic liquid.
[0059] The oxygen-containing compounds present in the hydrocarbon
feed may be alcohols, ethers, aldehydes or ketones, acetals, acids
or esters, water or a mixture of said compounds. Preferably, the
oxygen-containing compounds will contain 1 to 100 carbon atoms,
more preferably 1 to 50 carbon atoms, and still more preferably 1
to 20 carbon atoms.
[0060] Preferably, the oxygen-containing compounds will be alcohols
or acids.
[0061] Preferably, the alcohols will represent 1% to 20% by weight
of the hydrocarbon feed, and the acids will represent 0 to 50% by
weight of oxygen-containing compounds.
[0062] In the hydrocarbon feed, the hydrocarbons may be paraffins,
olefins, aromatics, acetylenics, naphthenes or any mixture of said
compounds.
[0063] Preferably, the hydrocarbons will contain between 1 and 100
carbon atoms, preferably between 1 and 50 carbon atoms, and more
preferably between 1 and 20 carbon atoms.
[0064] Preferably, the hydrocarbons are primarily constituted by
olefins and paraffins.
[0065] Preferably, the olefins will represent 0 to 50% by weight of
the hydrocarbon feed, and the paraffins will represent 50% to 100%
by weight of the hydrocarbon feed, the sum or the two values being
equal to 100.
[0066] The present invention will be particularly advantageous in
the case in which the hydrocarbon feed is constituted by the
effluent from a Fischer-Tropsch synthesis reactor.
[0067] The contact of the hydrocarbon feed with the extraction
phase containing at least one ionic liquid may be made continuously
or in a fractionated manner.
[0068] Separating the extraction phase containing at least one
ionic liquid from the hydrocarbon feed depleted in
oxygen-containing compounds may be carried out continuously,
semi-continuously or batchwise.
[0069] Advantageously, contact and separation of the hydrocarbon
feed and the extraction phase containing at least one ionic liquid
may be carried out using an industrial liquid-liquid extraction
apparatus.
[0070] Examples which may be cited are mixer-decanters (with
gravity decanting and/or by coalescence and/or electrostatically),
column extractors (baffle columns, plate columns, packed columns,
mechanically, pressurized or agitated stirred column), or
centrifugal extractors (staged or continuous differentials).
[0071] In a variation of the process of the invention, the
extraction phase containing at least one ionic liquid may be
regenerated after the contact and separation steps.
[0072] In a variation of the process of the invention, the
compounds extracted from the hydrocarbon feed, in particular
oxygen-containing compounds, may be recovered.
[0073] Regeneration of the extraction phase containing at least one
ionic liquid and recovery of the compounds extracted from the
hydrocarbon feed, in particular oxygen-containing compounds, may be
carried out by distillation, stripping, extraction, precipitation
or any other separation method known to the skilled person.
[0074] Preferably, regeneration of the extraction phase containing
at least one ionic liquid and recovery of the compounds extracted
from the hydrocarbon feed, in particular oxygen-containing
compounds, are carried out by distillation or stripping.
[0075] The diagram in FIG. 1 describes the most common
implementation of the process of the invention. However, the scope
of the invention is not limited thereto.
[0076] The hydrocarbon feed containing the oxygen-containing
compounds to be treated (Cox in FIG. 1) is introduced via line 1
into a contacter (A) where it is mixed with an extraction phase
containing at least one ionic liquid (Pex) in FIG. 1) introduced
via line 2.
[0077] The effluent from the contacter (A) is sent to the decanting
unit (B) via line 3 The fraction containing the hydrocarbon feed
depleted in oxygen-containing compounds (Cpur) is separated from
the extraction phase. This fraction Cpur is evacuated via line
4.
[0078] In an optional embodiment, the fraction containing the
extraction phase is sent via a line 5 to the separation unit
(C).
[0079] The compounds extracted from the hydrocarbon feed, in
particular oxygen-containing compounds, are separated and evacuated
via line 7.
[0080] The regenerated extraction phase is recycled via line 6.
[0081] It should be noted that the contacter (A) and decanting unit
(B) may be combined into a single device, for example a
liquid-liquid extraction column operating in counter-current
mode.
[0082] The following examples illustrate the invention without
limiting its scope.
EXAMPLE 1
[0083] Oxygen-containing compounds were extracted from a
hydrocarbon feed using different ionic liquids (in accordance with
the invention).
[0084] The hydrocarbon feed was obtained by distillation of a
Fischer-Tropsch synthesis effluent. The hydrocarbon feed was
composed of C.sub.6 to C.sub.10 olefins and paraffins and C.sub.3
to C.sub.7 alcohols.
[0085] The composition of said feed was obtained by gas
chromatography and Karl-Fischer analysis and is shown in Table I.
TABLE-US-00001 TABLE I Components Molar content Alcohols 6.2%
Olefins 38.4% (of which .alpha.-olefins) (32.5%) Paraffins 55.3%
Water 1700 ppm
[0086] The extraction tests were carried out in a small jacketed
glass reactor (40 cm.sup.3) provided with an argon inlet to
maintain it under an inert atmosphere. The temperature was
regulated by a heat conducting fluid which circulated inside the
jacket. All of the tests were carried out at a temperature of
30.degree. C.
[0087] The ionic liquids were synthesized in a laboratory in
accordance with conventional protocols described in the
literature.
[0088] The following were introduced into the jacketed glass
reactor: [0089] 2 ml of ionic liquid; and [0090] 4 ml of
hydrocarbon feed.
[0091] The mixture was then stirred at 1200 rpm using a magnetic
bar, for 1 h. At the end of this period, stirring was stopped and
the mixture was decanted for 15 minutes. The upper hydrocarbon
phase was then removed and analyzed.
[0092] The results obtained are shown in Table II and are given as
the molar percentage.
[0093] The following abbreviations are used:
[0094] n.d.=not determined
[0095] [BMI]: 1-butyl-3-methylimidazolium
[0096] [BMMI]: 1-butyl-2,3-dimethylimidazolium
[0097] [BMPyrr]: N-butyl-N-methylpyrrolidinium.
[0098] [(HOCH.sub.2CH.sub.2)MI]:
(2-hydroxyethyl)-1-methyl-3-imidazolium
[0099] [BMMorph]: N-butyl-N-methylmorpholinium
[0100] [NTF.sub.2]: bis-trifluoromethylsulphonylamide
TABLE-US-00002 TABLE II Extraction solvent Alcohol Olefins (of
which .alpha.-olefins) Paraffins Water [BMI][NTF.sub.2] 3.9% 38.1%
(32.6%) 57.9% nd [BMMI][NTF.sub.2] 3.0% 38.3% (32.4%) 58.7% nd
[BMPyrr][NTF.sub.2] 3.0% 38.7% (33.0%) 58.3% nd [BMI][BF.sub.4]
4.7% 37.9% (32.1%) 57.4% nd [BMMI][BF.sub.4] 4.9% 38.4% (32.8%)
56.7% nd [EMI][BF.sub.4] 5.1% 38.3% (32.5%) 56.6% nd
[BMI][SbF.sub.6] 3.6% 38.5% (32.7%) 57.8% nd
[BMI][CF.sub.3CO.sub.2] 0.4% 39.0% (33.6%) 60.6% 275 ppm
[EMI][CF.sub.3SO.sub.3] 2.0% 39.3% (33.6%) 58.8% nd
[(HOCH.sub.2CH.sub.2)MI][NTF.sub.2] 4.1% 38.5% (32.9%) 57.3% nd
[BMMorph][NTF.sub.2] 4.6% 37.9% (32.9%) 57.5% nd
EXAMPLE 2
[0101] The possibility of reducing the alcohol content in the
hydrocarbon feed by successive extraction with the ionic liquid
[BMI] [NTF.sub.2] was studied.
[0102] The following were introduced into a jacketed glass reactor:
[0103] 2 ml of [BMI][NTF.sub.2]; and [0104] 4 ml of hydrocarbon
feed.
[0105] The mixture was then stirred at 1200 rpm using a magnetic
bar, for 1 h. At the end of this period, stirring was stopped, and
the mixture was decanted for 15 minutes.
[0106] The upper hydrocarbon phase was removed, analyzed and
brought into contact with 2 ml of "fresh" [BMI][NTF.sub.2] for a
further extraction.
[0107] The results obtained are shown in Table III and are given as
a molar percentage. TABLE-US-00003 TABLE III Olefins Extraction no
Alcohol (of which, .alpha.-olefins) Paraffins 1 3.7% 38.6% (33.0%)
57.6% 2 1.1% 38.6% (33.8%) 60.3% 3 0.5% 37.3% (32.1%) 62.2%
EXAMPLE 3
[0108] The possibility of regenerating the extraction phase was
studied in the case of [BMI][CF.sub.3CO.sub.2]. The non volatile
nature of the ionic liquids allowed the extraction phase to be
regenerated very easily using the following protocol:
[0109] The following were introduced into a jacketed glass reactor:
[0110] 1.5 ml of [BMI][C.F.sub.3CO.sub.2]; and [0111] 6 ml of
hydrocarbon feed.
[0112] The mixture was then stirred at 1200 rpm using a magnetic
bar, for 1 h. At the end of this period, stirring was stopped, and
the mixture was decanted for 15 minutes. The upper hydrocarbon
phase was removed and analyzed. The lower liquid phase was taken
off under vacuum (10.sup.-1 mbar) for 2 hours at ambient
temperature.
[0113] A new volume (6 ml) of hydrocarbon feed was then added to
the ionic liquid phase for a new extraction.
[0114] The results obtained are shown in Table IV and are given as
a molar percentage. TABLE-US-00004 TABLE IV Olefins (of which
.alpha.- Extraction no Alcohol olefins) Paraffins Water 1 0.7%
40.1% (34.8%) 59.1% 162 ppm 2 (1.sup.st recycle) 0.8% 39.0% (33.8%)
60.1% 157 ppm 3 (2.sup.nd recycle) 1.2% 38.8% (33.6%) 59.9% 170
ppm
[0115] Without further elaboration, it is believed that one skilled
in the art can, using the preceding description, utilize the
present invention to its fullest extent. The preceding preferred
specific embodiments are, therefore, to be construed as merely
illustrative, and not limitative of the remainder of the disclosure
in any way whatsoever.
[0116] In the foregoing and in the examples, all temperatures are
set forth uncorrected in degrees Celsius and, all parts and
percentages are by weight, unless otherwise indicated.
[0117] The entire disclosures of all applications, patents and
publications, cited herein and of corresponding French application
No. 04/09.660, filed Sep. 10, 2005 are incorporated by reference
herein.
[0118] The preceding examples can be repeated with similar success
by substituting the generically or specifically described reactants
and/or operating conditions of this invention for those used in the
preceding examples.
[0119] From the foregoing description, one skilled in the art can
easily ascertain the essential characteristics of this invention
and, without departing from the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions.
* * * * *