Note: Descriptions are shown in the official language in which they were submitted.
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M-678
METHOD FOR INHIBITING COLOR CONTAMINATION
IN ETHANOLAMINE COMPOUNDS
FIELD OF THE INVENTION
The present invention is directed to a method of inhibiting
color formation and contamination in ethanolamine compounds. More
specifically, the present invention is directed to a method of
using amine compounds to inhibit the formation of oxygen containing
compound impurities which cause color contamination in ethanolamine
compounds.
BACKGROUND OF tHE INYENTION
Ethanolamine compounds, which include monoethanolamine,
diethanolamine and triethanolamine, are produced commercially by
reacting ethylene oxide, ammonia and water in a tubular reactor.
Oftentimes, the compounds generated by this method exhibit
an undesirable color and color instability developed over a period
of time. Nickel contained in the process system metallurgy is
thought to catalyze dehydrogenation reactions of by-product
ethylene glycol. It is thought that these reactions form oxygen
containing carbonyl compounds such as aldehydes and ketones.
The aldehyde compounds can undergo the aldol-condensation
reactions in the process system environment. Nickel may also
catalyze the direct decomposition of the ethanolamine compounds,
further forming carbonyl compounds.
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One theory postulates that these condensation polymer-
ization contaminants thus formed can cause color contamination
problems in the finished ethanolamine product.
Avoidance of color contamination increases the value of
the ethanolamine compound to the producer and minimizes the
off-specification product manufactured.
SUMMARY OF THE INVENTION
The present invention provides for a method for
inhibiting color formation in ethanolamine compounds comprising
adding to said ethanolamine compounds an effective amount for the
purpose of an amine compound of the formula
R"
, N - (CH2)x - R'
R
wherein R is H or OH; R' is - NH (CH2CH2NH)yH
where y is an integer from about 0 to about 20,
r\ r~ ~
--N NH, --N N - (CH2)2NH2. --N\__/N - (CH2)3 NH2
OH
CH3 - CH, - , --N((CH2 CH2)NH2)2,
OH
- NH(cH2cH2NH)zcH2 ~ where z is 0,1,2,3,4,
R'''
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OH
R" is H or (CH2)X-R' or -CH2 ~ and
R'''
OH OH
R''' is ~ CH2NHcH2cH2NHcH2 ~ O J
R R
and x is about 1 to about 3.
While effective in all ethanolamine compounds, the method
of the present invention is particularly effective at inhibiting
color formation in monoethanolamine, diethanolamine and
triethanolamine.
The present method entails ensuring that the amine
compounds are present in the ethanolamine reactor effluent.
DESCRIPTION OF THE RELATED ART
United States Patent 4,952,301, Awbrey, August 1990, dis-
closes a method of inhibiting the formation of polymeric fouling
deposits formed during the caustic washing of hydrocarbons. This
method employs the use of an ethylenediamine compound.
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United States Patent 3,819,710, Jordan, June 1974,
discloses a process for improving the color and color stability of
ethanolamine compounds. This process comprises hydrogenation of
crude mono - , di and triethanolamines using selected catalysts at
specific temperatures and pressures.
United States Patent 4,673,762, Paslean et al., June 1987,
discloses a method for decolorizing ethanolamine compounds. This
method employs adding to the ethanolamine compound an alkyleneoxide
such as ethylene oxide.
Japanese Patent Publication No. 1977 - [Showa 52]-28,770
discloses a method of decoloring ethyleneamines and alkanolamines.
This method is accomplished by heat treatment of the amine compound
in the presence of hydrogen and a catalyst. The catalyst can be
selected from a nickel-type, cobalt-type or nickel-cobalt-mixed
type hydrogenation catalyst.
European patent registration A1 0,004,015 discloses a
process for the manufacture of colorless ethanolamines. This
process entails carrying out the ethylene oxide, ammonium, water
reaction in the presence of phosphorous acid or hypophosphorous
acid or their compounds.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides for a method for inhibiting
color formation in ethanolamine compounds comprising adding to said
2 ~ ~ 1 r7
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ethanolamine compounds an effective amount for the purpose of an
amine compound of the formula
R"
, N - (CH2)x - R'
R
wherein R is H or OH; R' is - NH (CH2CH2NH)yH
where y is an integer from about O to about 20,
/~\ / \ ~
--N NH, --N N - (CH2)2NH2, --N\~_ /N - (CH2)3 NH2
OH
CH3 - CH, - , --N((CH2 CH2)NH2)2
OH
- NH(CH2CH2NH)zcH2 ~ where z is 0,1,2,3,4,
R'''
OH
R" is H or (CH2)X-R' or -CH2 ~ and
R'''
OH OH
R''' is ~ CH2NHCH2CH2NHcH2
R R
and x is about 1 to about 3.
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Of these compounds, tetraethylenepentamine is preferred.
In addition, exemplary compounds include diethylenetriamine and
triethylenetetramine. The tetraethylenepentamine is preferred as
it possesses a higher boiling point than the other two compounds
and thus can inhibit color formation at higher temperatures.
These amine compounds are also ashless compounds. This
makes their use desirable as industry is moving away from ash
containing compounds due to the clean-up costs involved.
These color inhibiting compounds can be added to the
ethanolamine compounds as neat materials or in solution form.
The preferred method of addition is as an aqueous solution.
The treatment should be added to the ethanolamine in
sufficient quantity to ensure there is enough of the amine
compound present to react with all the undesirable carbonyl
contaminants. Treatment dosages in the range of from about 1
part per million to about 10,000 parts per million parts of
ethanolamine compound may be employed. Preferably, the amine
compound is added in a range of about 5 parts per million to
about 5000 parts per million parts of the ethanolamine compound
to be treated.
The invention will be further illustrated by the
following examples which are intended merely for purpose of
illustration and are not to be regarded as limiting the scope of
the invention or the manner in which it may be practiced.
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EXAMPLES
Examp~e 1
In a 17 ml test tube, 10.0 ml of triethanolamine was
added. 40 ul of treatment (160 ul of 25% solution) was also
- 5 added along with a piece of steel. The remaining 7 ml of air
space was then purged with argon for 60 seconds and then the cap
was securely fastened. The test tube was then placed in a sili-
cone oil bath at the appropriate temperature for the specified
time indicated in the table. The time in days represents how many
days since the reaction was started. The yellow to brown colors
were then compared visually. The results of this first test
appear in Table I.
TABLE I
Triethanolamine color development
310 stainless steel
4,000 parts per million actives
Days
Since
Reaction Temperature ofOrder of Color
Started Bath (C) (Darkest to Lightest)
5 144 HS > TETA > NP > Blank, Blank No SS
7 204 HS > Blank No SS > TETA, NP, Blank
8 204 Blank No SS > HS > Blank > NP > TETA
9 204 Blank No SS > HS > Blank > NP > TETA
HS = Hydroxylamine sulfate
NP = Nonylphenol
TETA = Triethylenetetramine
Blank No SS - Blank run with no stainless steel present.
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The results of this test indicate that triethylene-
tetramine is more effective at inhibiting color formation than the
blank runs over a greater length of time and temperature.
Example 2
The procedure of example 1 was followed here. These
results are shown in Table II.
TABLE II
Triethanolamine color development
4000 parts per million active at 168C
Days
Since
Reaction Order of Color
Started(Darkest to Liqhtest)
With 310 SS Present
2 HS > TETA > EDA > Blank > NP > DETA = TEPA
4 HS > TETA > EDA > Blank > NP > DETA = TEPA
Without 310 SS Present
2 HS > EDA > NP > Blank = TETA = DETA = TEPA
4 HS > Blank > NP > EDA = TETA = DETA = TEPA
HS = Hydroxylamine Sulfate
EDA = Ethylenediamine
NP = Nonylphenol
: TETA = Triethylenetetramine
DETA = Diethylenetriamine
TEPA = Tetraethylenepentamine
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The polyamines diethylenetriamine and tetraethylenepent-
amine were always less colored than the blanks. The polyamines
ethylenediamine and triethylenetetramine proved better than the
blanks at longer heating periods with no steel present.
Example 3
The procedure of example 1 was followed. The tubes were
then wiped clean and inserted into a Hach spectrophotometer set at
410nm and calibrated with an unheated, untreated triethanolamine
sample. The results are presented in Table III as % transmittance
(%T)-
TABLE III
Triethanolamine Color Development
4000 parts per million active at 190C
No 310 SS present
%T %T %T %T
Treatment 24 Hours 48 Hours 62 Hours 24 Hours
---------Argon Purged----------- Air Purged
None 3.5,3.0 1.0,2.5 0.7 0.2
EDA - 64.0 - 4.0
DETA 73.0 63.0 - 7.5
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TABLE III (Cont'd)
%T %T %T %T
Treatment 24 Hours 48 Hours 62 Hours 24 Hours
---------Argon Purged----------- Air Purged
.
TEPA 58.5 - 11.0
AEP 44.0
BISAPP 66.5
TREN 27.0
HPHA 25.0
MD 35.0
EDA = Ethylenediamine
DETA = Diethylenetriamine
TETA = Triethylenetetramine
TEPA = Tetraethylenepentamine
AEP = N-(2-aminoethyl)piperazine
BISAPP = N,N'-bis(3-aminopropyl)piperazine
TREN = Tris(2-aminoethyl)amine
HPHA - Hydroxypropylhydroxylamine
OH OH
~\cH2NHcH2cH2NHcH2/~
wherein R is H or OH
These results show that the polyamines provide high percent
transmittance which is indicative of inhibition of color formation.
Example 4
The procedure of example 3 was followed except small pieces
of carbon steel were present. These results are shown in Table IV.
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TABLE IV
Triethanolamine color development
4000 parts per million active at 190C
Argon Purged
1010 Carbon Steel 9 CRlM0 Carbon Steel
%T %T %T
Treatment24 Hours 48 Hours 62 Hours
None 3.0 3.5 0.0
DETA 23.5 40.0 1.0
TETA 24.0 36.0 1.0
TEPA 38.0 52.0 1.0
DETA = Diethylenetriamine
TETA = Triethylenetetramine
TEPA = Tetraethylenepentamine
These results again show that the polyamines inhibited color
formation in the ethanolamines.
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.
