U.S. patent application number 09/767692 was filed with the patent office on 2001-07-26 for methods and compositions for inhibiting polymerization of ethylenically unsaturated hydrocarbons.
This patent application is currently assigned to BETZDEARBORN INC.. Invention is credited to Eldin, Sherif.
Application Number | 20010009968 09/767692 |
Document ID | / |
Family ID | 22686436 |
Filed Date | 2001-07-26 |
United States Patent
Application |
20010009968 |
Kind Code |
A1 |
Eldin, Sherif |
July 26, 2001 |
Methods and compositions for inhibiting polymerization of
ethylenically unsaturated hydrocarbons
Abstract
Methods and compositions for inhibiting the polymerization of
ethylenically unsaturated hydrocarbons are disclosed. Combinations
of aminophenol compound and either of phenylenediamine or
hydroxylamine compounds are effective at inhibiting this
polymerization under both processing and storage conditions.
Inventors: |
Eldin, Sherif; (Houston,
TX) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN
1941 ROLAND CLARKE PLACE
RESTON
VA
20191
|
Assignee: |
BETZDEARBORN INC.
Trevose
PA
|
Family ID: |
22686436 |
Appl. No.: |
09/767692 |
Filed: |
January 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09767692 |
Jan 24, 2001 |
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09186832 |
Nov 5, 1998 |
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6200461 |
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Current U.S.
Class: |
203/9 ; 203/8;
208/48AA; 208/48R; 585/950 |
Current CPC
Class: |
C09K 15/18 20130101;
C07C 7/20 20130101; Y10S 585/95 20130101; C07C 7/20 20130101; C07C
11/18 20130101 |
Class at
Publication: |
585/950 ;
208/48.0AA; 208/48.00R; 203/8; 203/9 |
International
Class: |
C07C 007/20 |
Claims
Having thus described the invention, what I claim is:
1. A method for inhibiting the polymerization of ethylenically
unsaturated hydrocarbons comprising adding to said hydrocarbons an
effective inhibiting amount of a composition comprising an
aminophenol compound and at least one of a phenylenediamine
compound and a hydroxylamine compound.
2. The method as claimed in claim 1 wherein said aminophenol
compound is selected from the group consisting of para-aminophenol,
meta-aminophenol and ortho-aminophenol.
3. The method as claimed in claim 1 wherein said phenylenediamine
compound has the formula: 4wherein R.sub.1, R.sub.2, R.sub.3 and
R.sub.4 are the same or different and are hydrogen, alkyl, aryl,
alkaryl, and aralkyl having about 1 to about 20 carbon atoms.
4. The method as claimed in claim 1 wherein said hydroxylamine
compound has the formula: 5wherein R.sub.5 and R.sub.6 are the same
or different and are hydrogen, alkyl, aryl, alkaryl, aralkyl or
hydroxyalkyl groups and have about three to about twenty carbon
atoms.
5. The method as claimed in claim 2 wherein said aminophenol
compound is ortho-aminophenol.
6. The method as claimed in claim 3 wherein said phenylenediamine
compound is selected from the group consisting of
N,N'-bis-di-sec-butyl-p-phenylen- ediamine and
N-phenyl-N'-(1,4-dimethylpentyl)-p-phenylenediamine.
7. The method as claimed in claim 4 wherein said hydroxylamine
compound is selected from the group consisting of
N,N'-diethylhydroxylamine and
bis-N,N'-(hydroxypropyl-hydroxylamine).
8. The method as claimed in claim 1 wherein said ethylenically
unsaturated hydrocarbons are undergoing processing.
9. The method as claimed in claim 1 wherein said ethylenically
unsaturated hydrocarbons are in storage conditions.
10. The method as claimed in claim 1 wherein said processing
conditions are at temperatures of about 95.degree. to about
125.degree. C.
11. The method as claimed in claim 1 wherein said ethylenically
unsaturated hydrocarbons are selected from the group consisting of
olefins and diolefins.
12. The method as claimed in claim 11 wherein said olefins and said
diolefins contain about 2 to about 20 carbons.
13. The method as claimed in claim 1 wherein said composition is
added to said hydrocarbon in an amount ranging from about 1 to
about 10,000 parts per million parts of said hydrocarbon.
14. A composition comprising an aminophenol compound and at least
one of a phenylenediamine compound and a hydroxylamine
compound.
15. The composition as claimed in claim 14 wherein said aminophenol
compound is selected from the group consisting of para-aminophenol,
meta-aminophenol and ortho-aminophenol.
16. The composition as claimed in claim 14 wherein said
phenylenediamine compound has the formula: 6wherein R.sub.1,
R.sub.2, R.sub.3 and R.sub.4 are the same or different and are
hydrogen, alkyl, aryl, alkaryl, and aralkyl having about 1 to about
20 carbon atoms.
17. The composition as claimed in claim 14 wherein said
hydroxylamine compound has the formula: 7wherein R.sub.5 and
R.sub.6 are the same or different and are hydrogen, alkyl aryl,
alkaryl, aralkyl or hydroxyalkyl groups and have about three to
about twenty carbon atoms.
18. The composition as claimed in claim 15 wherein said aminophenol
compound is ortho-aminophenol.
19. The composition as claimed in claim 16 wherein said
phenylenediamine compound is selected from the group consisting of
N,N'-bis-di-sec-butyl-p- -phenylenediamine and
N-phenyl-N'-(1,4-dimethylpentyl)-p-phenylenediamine.
20. The composition as claimed in claim 17 wherein said
hydroxylamine compound is selected from the group consisting of
N,N'-diethylhydroxylami- ne and
bis-N,N'-(hydroxypropyl-hydroxylamine).
21. The composition as claimed in claim 14 further comprising
either a phenylenediamine compound and a hydroxylamine
compound.
22. The composition as claimed in claim 14 further comprising an
ethylenically unsaturated hydrocarbon.
23. The composition as claimed in claim 14 wherein the weight ratio
of aminophenol compound to either of said phenylenediamine compound
and hydroxylamine compound ranges from about 1:9 to about 9:1.
Description
FIELD OF THE INVENTION
[0001] The present invention provides for methods and compositions
for inhibiting the polymerization of ethylenically unsaturated
hydrocarbons, such as olefins and diolefins.
BACKGROUND OF THE INVENTION
[0002] Common industrial methods for producing ethylenically
unsaturated monomers include a variety of purification processes
such as distillation to remove impurities. Purification operations
are often carried out at elevated temperatures and this can
increase the rate of undesired polymerization. Polymerization, such
as thermal polymerization, during the monomer purification process,
results not only in loss of desired monomer end-product, but also
in production efficiency caused by polymer formation and
agglomeration on process equipment. In heat requiring operations,
such agglomeration adversely affects heat transfer efficiency.
[0003] Typically the monomers are stabilized with the addition of
substances which will act as inhibitors or retarders of
polymerization.
[0004] Certain ethylenically unsaturated monomers such as the
diolefins butadiene and isoprene will polymerize when left in
storage tanks and during transportation at temperatures as low as
room temperature. This polymerization is initiated by reaction of
the diolefin monomer with oxygen present in the monomer containing
system. This reaction will form peroxides and free radical species
which will perpetuate the reaction with the diolefin monomer.
[0005] Various approaches have been attempted with regard to this
problem of polymerization. U.S. Pat. No. 3,148,225 teaches that
N,N-dialkylhydroxylamines will inhibit the polymerization of
popcorn polymer formation in olefin monomer recovery systems. In
comparative studies, p-aminophenol was less effective than the
hydroxylamines at inhibiting popcorn polymer formation. U.S. Pat.
No. 3,342,723 tests p- and o-aminophenols for inhibiting fouling of
hydrocarbon liquids. These compounds proved effective at inhibiting
the formation and adhesion of coke-like deposits during refinery
operations. o-phenylenediamine was also demonstrated to be
effective in the oil refining apparatus.
[0006] U.S. Pat. No. 5,510,547 teaches that a combination of a
phenylenediamine compound and a hydroxylamine compound is effective
as inhibiting the polymerization of vinyl aromatic monomers during
processing conditions. U.S. Pat. No. 4,720,566 teaches that a
combination of a hydroxylamine and a phenylenediamine compound is
effective at inhibiting the polymerization of acrylonitrile during
its production.
DETAILED DESCRIPTION OF THE INVENTION
[0007] The present invention provides for methods and compositions
for inhibiting the polymerization of ethylenically unsaturated
hydrocarbons comprising adding an effective inhibiting amount of a
composition comprising an aminophenol compound and at least one of
a phenylenediamine compound and a hydroxylamine compound
"(Aminophenol compositions").
[0008] The ethylenically unsaturated monomers are characterized as
polymerizable ethylenically unsaturated hydrocarbons and include
olefins and diolefins. The olefins contain about 2 to about 20
carbon atoms, preferably 2 to 8 carbon atoms and the diolefins are
conjugated and contain about 2 to about 20 carbon atoms with 4 to 6
carbon atoms preferred. Examples of these compounds include
ethylene dichloride, ethylene glycol, aromatics from ethylene
plants and pyrolysis gasoline.
[0009] The aminophenol compounds generally have the formula: 1
[0010] where the amino group can be ortho, meta or para to the
hydroxyl group. Preferably, the o-aminophenol is preferred.
[0011] The phenylenediamine compounds useful in the present
invention generally have the formula: 2
[0012] wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are the same
or different and are hydrogen, alkyl, aryl, alkaryl or aralkyl
groups having about 1 to about 20 carbon atoms. Preferably the
phenylenediamine compound is selected from the group consisting of
N,N'-bis-di-sec-butyl-p- -phenylenediamine and
N-phenyl-N'-(1,4-dimethylpentyl)-p-phenylenediamine.
[0013] The hydroxylamine compounds useful in the present invention
generally have the formula: 3
[0014] wherein R.sub.5 and R.sub.6 are the same or different and
are hydrogen, alkyl, aryl, alkaryl, aralkyl or hydroxyalkyl groups
and have about three to about twenty carbon atoms. The preferred
hydroxylamine compounds are selected from the group consisting of
N,N'-diethylhydroxylamine (DEHA) and
bis-N,N'-(hydroxypropyl-hydroxylamin- e) (HPHA).
[0015] The aminophenol compositions of the present invention are
effective at inhibiting the polymerization of ethylenically
unsaturated monomers during both storage and processing conditions.
Storage conditions also include transportation of the monomers.
These conditions will usually have oxygen present and can be at
elevated temperatures of up to 100.degree. C. The processing
conditions are usually distillation and purification processes and
are run at elevated temperatures of 95.degree. and 125.degree. C.
where oxygen can be present or absent.
[0016] For purposes of the present invention, the term "effective
amount for the purpose" is that amount of aminophenol compositions
necessary to inhibit polymerization of the ethylenically
unsaturated monomers. This amount will vary according to the
conditions under which the monomers are subjected during the
storage and/or handling thereof. During processing, for example,
high temperatures and higher monomers contamination will require
larger amounts of the aminophenol compositions.
[0017] Preferably, the total amount of the aminophenol compositions
added to the ethylenically unsaturated monomer will range from
about 1 part to about 10,000 parts per million parts of monomer.
More preferably, the aminophenol compositions are added at a range
of about 1 part to about 100 parts per million parts monomer.
[0018] The weight ratios of aminophenol compound to the other
compounds present in the aminophenol compositions is presented in
Table A below.
1 TABLE A Aminophenol Compound Phenylenediamine Compound 1:9 to 9:1
Hydroxylamine Compound 1:9 to 9:1
[0019] Accordingly, it is possible to produce a more effective
vinyl aromatic monomer polymerization inhibition treatment than is
obtainable by the use of one ingredient alone when measured at
comparable treatment levels. This enhanced activity will allow for
the concentration of each of these ingredients to be lowered and
the total quantity of polymerization inhibitor particularly at
higher processing temperatures may be reduced.
[0020] The aminophenol compositions of the present invention may be
added to the ethylenically unsaturated hydrocarbon as either a
dispersion or as a solution using a suitable liquid carrier or
solvent. Any solvent that is compatible with the individual
ingredients and with the monomer may be employed.
[0021] The aminophenol compositions may be added to the
ethylenically unsaturated hydrocarbon vinyl aromatic by any
conventional method, either as individual components or as a
combination of components. It is preferred that the ingredients be
added to the monomer as a single treatment.
[0022] This invention will now be further described with reference
to a number of specific examples which are to be regarded solely as
illustrative and not as restricting the scope of the invention.
EXAMPLES
[0023] 20% uninhibited isoprene in heptane was placed in a pressure
vessel. This mixture was then purged once with nitrogen before
placing it under 100 psi nitrogen. The pressure vessel was then
placed in a 100.degree. C. water bath for 4 hours allowing
polymerization of the diolefin. The mixture was then allowed to
cool at room temperature. The sample was evaporated and the
remaining gums/polymer weight was obtained.
[0024] The chemicals employed in the testing are summarized in
Table.
2 TABLE o-AP ortho-aminophenol DEHA N, N'-diethylhydroxylamine PDA
I N, N'-bis-di-sec-butyl-p-phenylened- iamine PDA II
N-phenyl-N'-(1,4-dimethylpentyl)-p-phenylenediamine
[0025] The results of this testing for a combination of aminophenol
compound and phenylenediamine are presented in Table I.
3TABLE I Heat Induced Gum Test Treatment Total (.mu. Moles) Gums
(mg/100 ml) o-AP 1.1 52 DEHA 1.1 50 PDA I 1.1 6 o-AP/DEHA (1:1) 1.1
16 o-AP/PDA I (1:1) 1.1 0.4
[0026] These results demonstrate that the combination of an
aminophenol compound and either a hydroxylamine compound or a
phenylenediamine compound was more effective than the particular
individual component.
[0027] The concentration of the individual components was lowered
by half, but the ratio between two component treatments was kept
equimolar in the next study. These results are presented in Table
II.
4 TABLE II Treatment Total (.mu. Moles) Gums (mg/100 ml) o-AP 0.55
59 DEHA 0.55 102 PDA I 0.55 32 o-AP/DEHA (1:1) 0.55 54 o-AP/PDA I
(1:1) 0.55 16
[0028] These results also demonstrate that the combination of an
aminophenol compound with either a hydroxylamine compound or a
phenylenediamine compound is more effective at inhibiting
polymerization than the individual components.
[0029] Additional studies were performed using the same components,
but with a constant final dosage. These results are presented in
Table III.
5TABLE III Heat Induced Gum Test Treatment Total (ppm) Gums (mg/100
ml) o-AP 2 46 DEHA 2 55 PDA I 2 64 PDA II 2 45 o-AP/DEHA (1:1) 2 21
o-AP/PDA I (1:1) 2 34 o-AP/PDA II (1:1) 2 35 o-AP/DEHA/PDA I
(1:1:1) 2 11
[0030] These test results not only demonstrate the enhanced
activity occasioned by use of the combination of aminophenol
compound with either a phenylenediamine or a hydroxylamine
compound, but also the excellent results occasioned by use of all
three compounds together.
[0031] Further testing was performed with DEHA and o-AP at a
constant dosage of 1 ppm. These results are presented in Table
IV.
6TABLE IV Heat induced Gum Test o-AP (%) DEHA (%) Gums (mg/100 ml)
100 0 51 75 25 45 67 33 46 50 50 31 33 67 36 25 75 47 0 100 81
[0032] These results demonstrate the synergy between o-AP and DEHA
at inhibiting ethylenically unsaturated hydrocarbon
polymerization.
[0033] While this invention has been described with respect to
particular embodiments thereof, it is apparent that numerous other
forms and modifications of this invention will be obvious to those
skilled in the art. The appended claims and this invention
generally should be construed to cover all such obvious forms and
modifications which are within the true spirit and scope of the
present invention.
* * * * *