Note: Descriptions are shown in the official language in which they were submitted.
2G~
-- 1 --
Case EI-5918
MIDDLE DISTILLATE FUEL HAVING IMPROVED STORAGE STABILITY
This invention relates generally to improving the
stability of middle distillate fuels and more particularly
to stabilized middle distillate fuel compositions which
contain a combination of N,N-dimethylcyclohexyl amine and
a Mannich Base.
Middle distillate fuels such as diesel oil, fuel
oil, jet fuel and kerosene when stored for long periods of
time are subject to the formation of color and solid depos-
its. The deposits accumulate on filters causing the fil-
ters to become plugged. Various additives and combina-
tions of additives have been employed to reduce color and
deposit formation. For example: U.S. Patent 2,984,550
discloses the use of Mannich bases derived from phenols,
formaldehyde and polyamines for stabilization: U.S. Patent
3,490,882 discloses stabilized petroleum distillate fuel
oils containing N,N-dimethylcyclohexylamine antioxidant
and a N,N'-di(ortho-hydroxyarylidene)-1,2-alkylenediamine
metal deactivator such as N,N'-disalicylidene-1,2-
propylenediamine; U.S. Patent 4,166,726 discloses a fuel
additive which is a mixture of a polyalkylene amine and a
Mannich Base; and U.S. Patents 4,501,595 and 4,533,361
disclose diesel oil which contains a condensate of tetra-
ethylene pentamine, paraformaldehyde, a hindered phenol
X~ 3
such as 2,6-di-t-butylphenol and polyisobutenyl succinic
anhydride.
The effectiveness of any particular type of addi-
tive combination can vary with different fuel stocks and
combinations which are more effective at the same total
additive concentration reduce treatment cost. We have now
discovered novel, synergistic additive combinations which
include certain Mannich Bases and provide middle distill-
ate fuels having generally improved storage stability
compared to fuels containing the same total concentrations
of either N,N-dimethylcyclohexylamine antioxidant alone or
N,N-dimethylcyclohexylamine in combination with an N,N'-di-
(ortho-hydroxyarylidene)-1,2-alkylenediamine metal deacti-
vator.
In accordance with this invention, there is pro-
vided a fuel additive concentrate comprising a mixture of
N,N-dimethylcyclohexylamine and a Mannich Base which is
the reaction product of an aldehyde, an amine and an alkyl
phenol selected from (a) hindered phenol having the
formula:
OH
Rl ~ R2
R3
where Rl, R2, R3 are independently selected
25from hydrogen, t-butyl, t-amyl and isopropropyl, provided
%~ 3
that at least one of Rl, R2 and R3 is hydrogen and
at least one of Rl and R2 is t-butyl, t-amyl or
isopropyl; and (b) p-alkyl phenol having the formula:
OH
R4
where R4 is Cg to C30 alkyl.
The concentrate can also contain a N,N'-di(ortho-hydroxy-
arylidene)-1,2-alkylenediamine metal deactivator such as
N,N'-disalicylidene-1,2-propylenediamine. Also provided
is a stabilized fuel containing from 1 to 1400 mgs/liter
of N,N-dimethylcyclohexylamine, from 0.5 to 1100 mgs/liter
of Mannich Base and from O to 400 mgs/liter of an N,N'-
di~ortho-hydroxyarylidene)-1,2-alkylenediamine.
The N,N-dimethylcyclohexylamine component of the
compositions of the invention is a commercially available
fuel antioxidant.
The N,N'-di(ortho-hydroxyarylidene)-1,2-alkylenedi-
amine component, in which, typically, the arylidene radi-
cal contains 6-7 carbon atoms and the alkylene radical
contains 2-3 carbon atoms, is a metal deactivator whose
presence in combination with the other components provides
2~01~3
fuel compositions of the invention having the most im-
proved stability. The preferred metal deactivator is
N,N'-disalicylidene-1,2-propylenediamine which is com-
mercially available.
The Mannich Base component of the invention is pro-
duced by the Mannich condensation reaction of a hindered
or p-alkyl phenol, an aldehyde, such as formaldehyde,
ethanal, propanal, and butanal (preferably formaldehyde in
its monomeric form or paraformaldehyde) and primary and
secondary amines.
The hindered phenols which are useful in preparing
the Mannich Base component of the invention are phenols
which are characterized by the presence of at least one
and preferably two ortho-t-butyl, t-amyl, and/or isopropyl
groups. Specific examples of such hindered phenols in-
clude: 2,4-di-t-butylphenol, 2,4-diisopropylphenol, 2,6-
diisopropylphenol, 2-t-butylphenol, and 2-t-amylphenol
with 2,6-di-t-butylphenol being most preferred.
The p-alkyl phenols which are useful in preparing
the Mannich Base component of the invention are those
which contain from 9 to 30 carbons which can be arranged
in either a straight or a branched chain. Preferred
phenols are Cg to C12 p-alkylphenols such as, for
example, p-nonylphenol and p-dodecylphenol.
The amines which are useful in preparing the
Mannich Base component of the invention are primary and
2~
secondary amines which can be selected from one or more
of:
A. alkyl monoamines of the formula;
R5
HN
\ R6
where R5 is selected from H and C1 to C5
alkyl, and R6 is selected from Cl to C14 alkyl and
the group -(CH2)n-OR7 where n = 1 to lO and R7 is
10Cl to C20 alkyl,
B. alkyl diamines of the formula;
R5
¦ A
HN R8 N \
B
where R5 is selected from H and Cl to C5
alkyl, R8 is C1 to C6 alkylene and A and B are in-
dependently selected from H, C1 to C5 alkyl, mono-
hydroxysubstituted Cl to C5 alkyl, and the group
(CH2)n-OR7 where n = 1 to lO and R7 is Cl to
C20 alkyl,
2~ 3
C. ethylene polyamines of the formula;
H2N~ (CH2 ) 2NH~nH
where n - 2 to 10, and
D. cyclic amines of the formula;
/(CH2)n
HN X
(CH2)m
where n and m are independently integers from 1 to
3, X is selected from CH2, O, S and NRg where Rg is
H, C1 to C10 alkyl, or the group (CH2)n-NH2
where n is 1 to 10. The alkyl groups can have a branched
chain.
Specific examples of such amines include 1,3-di-
aminopropane, 1,2 diaminopropane, dimethylamine, diethyl-
amine, dipropylamine, dibutylamine, N,N-dimethyl-1,3-
diaminopropane, l,l-dimethyldodecylamine, mixed C12-
C14 t-alkyl amines, 2-methyl-1,5-pentadiamine,
ethylenediamine; cyclic amines such as piperazine,
aminoethylpiperazine, morpholine and thiomorpholine; and
ethylene polyamines such as diethylene triamine and
triethylene tetraamir.e.
The Mannich Base can be formed by reacting from 1
to 5 moles of aldehyde, from about 1 to 2 moles of amine
and from 1 to 4 moles of phenol at a temperature of from
O~C to 150~C for 0.5 to 10 hours. An inert solvent such
2~3
-- 7 --
as isopropanol can be used which is distilled from the
product along with water formed in the reaction.
The Mannich Base product is usually a mixture of
materials which may contain unreacted ingredients,
especially the phenol. The Mannich Bases can be isolated
from the product mixture but the product mixture itself
can conveniently be used in forming the compositions of
the invention. Examples of Mannich reactions and products
are illustrated below:
2~
OH R5 OH R5
+ HCHO + HN > j~~ CH2 - N
R4 R6 R4 I R6
or
Rl
HO ~ + HCHO + NH2 ~CH2) 3 NH2
R2
Rl
HO >\~ CH2--NHtcH2) 3 NH2 +
R2 II
Rl
)=`~ / CH2
HO ~ ~ CH2--N NH +
,~ CH2 CH2
R2 III CH2
Rl Rl
HO ~ / CH2 ~ OH
2 0 R2 IV CH2 R2
2~3~ 3
_ g _
where Rl, R2, R4, Rs and R6 are as
defined above.
The additive mixtures of the invention are usually
prepared and marketed in the form of concentrates for
addition to the fuel by the customer although the in-
dividual components could be added directly into the
fuel. Suitable proportions of additives in the concen-
trates of the invention, based on the total weight of
concentrate, include from 25 to 95 wt% N,N-dimethylcyclo-
hexylamine, from 0 to 25 wt% N,N'-di(ortho-hydroxyaryli-
dene)-1,2-alkylenediamine and, from 5 to 75 wt% Mannich
Base.
The concentrates are added to the fuel in effective
amounts to provide improved stability. Suitable amounts
of additive concentrate in the fuel are from 1 to 500
pounds per thousand barrels (Ptbs) (3 to 1500 mgs/liter,
preferred 2.5 to 100 Ptbs or 8 to 300 mgs/liter). This
will provide a stabilized fuel containing from 1 to 1400
mgs/liter (preferred 2 to 250 mgs/liter) N,N-dimethylcyclo-
hexylamine, from 0 to 400 mgs/liter (preferred 0 to 100
mgs/liter) N,N'-di(ortho-hydroxyarylidene)-1,2-alkylene-
diamine metal deactivator and from 1 to 1100 mgs/liter
(preferred 1 to 250 mgs/liter) of Ma~nich Base. When
used, the metal deactivator is present in amounts of 1.0%
to 25 wt% of concentrate or .3 to 400 mgs/liter of fuel.
The concentrates can also contain an inert diluent or
Z0~0183
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solvent which can be, for example, an aliphatic hydro-
carbon such as kerosene or an aromatic hydrocarbon such as
xylene.
The middle distillate fuels whose stability is
improved by the invention typically include those boiling
within a temperature range of 150~-400DC which may
commonly be labeled as kerosene, fuel oil, diesel oil, No.
1-D, or No. 2-D.
The compositions of the invention are further
illustrated by, but are not intended to be limited to, the
following examples wherein parts are parts by weight
unless otherwise indicated.
Example 1
A Mannich Base reaction product of formaldehyde,
1,3-diaminopropane and 2,6-di-t-butylphenol is prepared by
the following process.
Dissolve 103 grams (0.5 mole) of 2,6-di-t-butyl-
phenol in 100 grams of isopropyl alcohol (IPA) in a 500 ml
round bottom flask. Add 18.5 grams (0.25 mole) of 1,3-di-
aminopropane dropwise over 15 minutes while the contents
of the flask are stirred. There is an exotherm observed
as the amine is added. Cool the contents of the flask to
below 30C and add a 10% excess, (44.6 grams 0.55 mole) of
37% aqueous formaldehyde solution dropwise over 30 minutes
while maintainin~ the temperature below 3G~C. Heat the
contents of the flask to reflux and continue to reflux for
20~0183
-- 11 --
one hour. Switch from reflux to distillation and distill
off IPA/water mixture to 105~C. Apply 28 in. Hg vacuum to
remove residual materials. The total product yield is
122.2 or 96~ of theory which contains compounds of the
Structure III and IV.
Additive blends of the reaction product were
prepared and tested in different fuels using both the D
4625 43C (110F) Storage Stability Test, in which the
color change (using ASTM D1500) and the total insolubles
in the fuel (reported in mg/100 ml) are determined on 400
ml samples stored for 13 weeks in the dark and the F-21-61
149C (300F) Accelerated Stability Test in which the
color change and insoluble gums are determined on 50 ml
samples heated to 149~C for a selected time, which was 90
minutes, allowed to cool in the dar~, tested for color
(ASTM D1500), and then filtered (using a 4.25 cm Whatman
#l filter paper) and the filtrate discarded. The filter
is washed clean of fuel with isooctane and measured for
deposits by comparison with a set of reference papers.
The blend compcsitions and test results in comparison to
untreated fuel and blends without the Mannich Base product
are reported in Table I below.
:Z010~83
0 N æ O ~, N ~ UU N _
~ ~ g O It~
~ o O In ~ ~I N _
æ ~ N ~_ ~11 N _
Nl N O O N Nl N ~ Nl N N
O O O O It~ It~ N
_I O O O O _I ~ N N
'O 11'~ O~ O U~ _
_ ~ O -- ~I N r~l ~1 1~ N
2~ Si~ y~y~O , Si~ U- ~ 1~
~_ NlO. O O _ l~i Ut _ Nl 1~1 ~
~ 00.0 O, ,~ _1 01~ ~ _1 ~'0
--I L~ 0 N 0~ O ~ N r~ t 1/~ C 1~
~ O O ~ Y ~ ..
l ~t Nl ~ ' ' ~-- ~ I ~ ~ J
.C ~~00 U~ I _ ~ InO~ _
~-I OOO O _l 01~ _1
~D N O~ O U~ 1 IU Ull ~ _
N O O ~1 ~ ~ -- X
~ ~1 o o o o ~ ~ , _ .C ~ ~ ~ Y y
Nl . , , , Nl ~ C O
_1 o O o, o, _1 ~ _~ U~ 0 ~ C ~
o, C _ ~ ._ ._ ._ ._
I al ~ o~ J ~J ~ 0 ,~) ,10 ,t ~ ,~'1
C N~ ~ 0 ~ ~ ~.1 Q ~ _ ~, z z
- Zl -
2010183
- 13 -
A significant difference in stability at 149C is
indicated by a color difference of about l/2 number and/or
a deposit difference of 2 numbers and a significant dif-
ference in stability at 43C is indicated by a color dif-
ference of about 1/2 number and a deposit difference of
20%. The results in Table I show that the blends of the
invention which contain Mannich Base in addition to DMCA
or DMCA and MDA gave significantly better overall stabil-
ity when compared to comparable blends which did not con-
tain the Mannich Base, for example, blend 3 vs blend 2 and
blend 5 vs blend 4 of Fuel #1.
Example 2
A Mannich Base reaction product of formaldehyde,
dimethylamine, and 2,6-di-t-butylphenol is prepared by the
fcllowing process.
Dissolve 103 grams (0.5 mole) of 2,6-di-t-~utyl-
phenol in 100 grams of IPA in a 500 ml round bottom flask
and add 72 grams (0.64 mole) of a 40% aqueous dimethyl-
amine solution. Cool the mixture to about 30C and add
dropwise with stirring 44.6 grams (0.55 mole) of 37%
formaldehyde while keeping the mixture at a temperature
below 40C. Heat the mixture to reflux and reflux for 4
hours. Remove IPA/water by distillation and apply vacuum
to remove residual materials. The product yield is 113
grams or 86% of theory which contains N,N-dimethyl-3,5-di-
t-butyl4-hydroxybenzylamine.
20~V~3
Additive blends of the above reaction product were
prepared and tested in different fuels using the test
procedures described in Example 1. The blend compositions
and test results in comparison to untreated fuel and
S blends which did not contain the Mannich Base product are
reported in Table II below.
201018~3
O ~ o ~ ~ O 3 3 3
C~ W ~ O l_
IN ~ W IN . . . ~
N ~ IW ~ ~ , . . IW _
_ ~ W 1~ O O N
N ~ 1~ ~ W 1~ O O N g 1
o~w l_- ~ l_ o ooo 1- C ~
W ~ W IN _ I O W 1~ N _ O O 0~0 IN N _.
w w IW ê~~ w IW ~ ~ ~ ~ IW ~ m
N ~ O ~O ~ ~ ~ _
.I_ _ OOOOI C
3 IN _ W ~ 1~ C W O _ ~N IN _ ~
~i ~i O ~ ~S ~
IW~ O ~ N IW _
N N IO~N l_ I_
N N IN~ N IN ~ O _ W IN ~
~ W IW _ ~ N IW ~ ~ ~ - O _
_ ~ 1~1~ O V- Vi
O N 1~W ~ 1~ . , 1~
~o ~ O. ~ o
20~0~3
- 16 -
The results indicated that the blends containing
Mannich Base gave fuels having significantly improved
stability except in`the case of Fuel #4 where the results
were mixed.
Example 3
A Mannich Base reaction product of formaldehyde,
C12-C14 t-alkyl amine mixture (Primene 81R) and 2,6-
di-t-butyl phenol is prepared by the process described in
Example 2 using 95.5 grams (0.5 mole) of Primene 81R in
place of the dimethylamine. The product yield is 200
grams or 82% of theory which contains N-[3,5-di-t-butyl-4-
hydroxybenzyl~-mixed C12-Cl4 t-alkyl amines.
Additive blends of the above reaction product were
prepared and tested in #2 diesel fuel using the test
procedures described in Example 1. The blend compositions
and test results are reported in Table III below.
TABLE III
~osition Pounds Per m~nd Barrels
~onents 1 _ 3 4 5 6
~MCA 0.0 9.5 0.0 4.75 l9.0 0.0 9.5
MDA 0.0 0.5 0.5 0.50 l.0 l.0 l.0
Mannich ~ 0.0 0.0 9.5 4.75 0.0 19.0 9.5
Total
Additives 0.0 10.0 10.0 lO.0 20.0 20.0 20.0
21;~10183
-- 17 --
~st Results
149C (F-21-61)
Conponents 1 _ _ _ 5 6
Color L5.5 L4.5 L5 L4.5 L4.5 L5 L4.5
Deposit 8 6 4 3 4 3 2
43C(D 4625)
Comporlents 1 2 3 _ 5 6
~olor L6.5 L6 6 L6 5.5 L6 L5.5
Deposit 8.3 3.2 5 2.8 3.3 5 3
The results indicate that blends 4 and 7 according
to the invention which contain the Mannich Base in addi-
tion to DMCA and MDA have better stability at the same
total additive levels compared to blends 2 and 5 contain-
ing only DMCA and MDA.
Example 4
A Mannich Base reaction product of formaldehyde,
1,2-diaminopropane, and 2,6-di-t-butyl phenol is prepared
by the following process.
Dissolve 103 gm (0.5 mole) of 2,6-di-t-butyl phenol
in 100 grams of IPA in a 500 ml roundbottom flask and add
18.5 grams (0.25) moles of 1,2-diaminopropane. Cool this
mixture to about 30C and add dropwise with stirring 44.6
grams (0.55 mole~ of 37% formaldehyde while 3~eeping the
temperature of the mixture below 40~C. Heat the mixture
to reflux and reflux for 1 hour. Remove IPA/water by
2010183
- 18 -
distillation and apply vacuum to remove residual materi-
als.
Additive blends of the above reaction product were
prepared and tested in Fuel #1 fuel using the test proce-
duree described in Example 1. The blend compositions and
results are reported in Table IV below.
TABLE IV
Ccmposition P~s Per Tha~nd Barrels
Canponents 1 _ 3 _ 5
~MCA 0.0 5.0 4.75 4.0 3.8
MDA 0.0 0.0 0.25 0.0 0.25
Mannich Base O.0 O.O O.OO l.O 0.95
Total Additives O.O 5.0 5.0 5.0 5.0
Test RY~ts
149C (F-21-61)
Can~ponents 1 _ 3 _ 5
Color L7 L3.5 L3 L3 L2.5
Deposit 13 5 4 3 3
43C (D 4625)
C~q~onents 1 2 3 4 5
Color L5 4 4 4 L4
Deposit 6.8 3.2 2.5 2.6 1.7
The results indicate that blend 4 o~ the invention
containing the Mannich Base has improved stability com-
pound to blend 2 which containing DMCA alone. Blend 5
containing the Mannich Base has improved stability over
blend 3 which contained DMCA and MDA alone.
2~10183
Example 5
A Mannich Base reaction product of formaldehyde,
N,N-d~methyl-1,3-diaminopropane, and p-dodecylphenol was
prepared by the following procedure.
Combine 262.4 grams (1.0 mole) of the alkyl (C12)
phenol with 102.2 grams (1.0 mole) of N,N-dimethyl-1,3-di-
amino-propane and add 89.2 grams ~1.1 mole) of 37% formal-
dehyde with stirring while keeping the temperature below
40C. Heat the mixture to 100C for two hours and then
remove water by distillation (100C - 28 in vacuum). The
product yield is 176 grams or 93% of theory which contains
N,N-dimethyl-N'-~2 hydroxy-5-dodecylbenzyl]-l~3-diamin
propane.
Additive blends of the above reaction product were
prepared and tested in midcontinent #2 diesel fuel using
the test procedures described in Example 1. The blend
compositions and results are reported on Table V below.
TABLE V
C~sition P~s Per Tho~nd Barrels
Com~onents 1 2 3 _ S
nMCA 0.0 4.75 2.05 9.5 4.5
Mn~ 0.0 0.25 0.25 0.5 0.5
M~nnich ~ 0.0 0.00 2.70 0.0 5.4
Total Additives 0.0 5.0 5.0 lO.0 10.0
2010183
- 20 -
Test R~ts
149C (F-21-61)
Camponents 1 2 3 4 5
Color 8 3 L3 L2.5 L2.5
D~posit 13 10 5 5 5
43C (D 4625)
Camponents 1 _ 3 4 5
Color L3.5 L3.5 3 I;3.5 L3.5
Deposit 6 4 3.5 3 2.4
The results indicate that blends 3 and 5 of the in-
vention have over-all improved stability compared to
blends at the same total additive level which did not in-
clude the Mannich Base.
