Mineral oil middle distillate compositions

Mineral oil middle distillate compositions based on hydrocarbon mixtures whose boiling range begins at above 160.degree. C. and ends at below 420.degree. C. contain, as paraffin dispersants, reaction products of aminoalkylenecarboxylic acids with primary or secondary long-chain amines.

The present invention relates to mineral oil middle distillate compositions 
based on a hydrocarbon mixture which contain, as a paraffin dispersant, a 
reaction product of an aminoalkylenecarboxylic acid with primary or 
secondary long-chain amines. 
Middle distillates, for example gas oils, diesel oils or fuel oils, which 
are obtained by distillation from mineral oils have different contents of 
paraffins, depending on the origin of the crude oil. Solid paraffins 
separate out at relatively low temperatures (cloud point, CP). On further 
cooling, the lamellar n-paraffin crystals form a "house-of-cards 
structure" and the middle distillate sets although the predominant part of 
the middle distillate is still liquid. The flowability of the mineral oil 
middle distillates is considerably adversely affected by the precipitated 
n-paraffins in the temperature range between the cloud point and pour 
point. The paraffins block filters and cause nonuniform fuel feed to the 
combustion units or completely stop this feed. 
It has long been known that the crystal growth of the paraffins in the 
mineral oil middle distillates can be modified by suitable additives. 
Effective additives on the one hand prevent middle distillates from 
forming such house-of-cards structures and becoming solid at temperatures 
a few degrees Centigrade below the temperature at which the first paraffin 
crystals crystallize out and, on the other hand, form fine, well 
crystallized, separate paraffin crystals which pass through filters in 
motor vehicles and heating units or at least form a filter cake which is 
permeable to the liquid part of the middle distillates, so that 
trouble-free operation is ensured. 
A disadvantage of this prior art is based on the fact that, because they 
have a higher density than the liquid part, the precipitated paraffin 
crystals show an increasing tendency to settle on the bottom of the 
container during storage. This results in the formation of a phase which 
is homogeneous in the upper part of the container and has a low paraffin 
content, and a two-phase paraffin-rich layer at the bottom. Since both in 
vehicle tanks and in storage or delivery tanks of the mineral oil dealers 
the middle distillate is generally taken off slightly above the bottom of 
the tank, there is a danger that the high concentration of solid paraffins 
will lead to blockage of filters and metering apparatuses. This danger is 
the greater the further the storage temperature falls below the 
precipitation temperature of the paraffins (cloud point), since the amount 
of paraffin which separates out is a function of the temperature and 
increases with decreasing temperature. 
The paraffin crystal modifiers, is the flow improvers, are polymers which 
change the crystal growth of the n-paraffins by crystallization 
(interaction). The flow properties of the middle distillate are 
advantageously affected at relatively low temperatures. According to DIN 
51,428, the efficiency of the flow improvers is expressed indirectly by 
measurement of the cold filter plugging point (CFPP). 
The conventional ethylene copolymers, especially copolymers of ethylene and 
unsaturated esters, are used as cold flow improvers. DE 11 47 799 and DE 
19 14 756 describe, for example, copolymers of ethylene with vinyl 
acetate, containing from 25 to 45% by weight of vinyl acetate or vinyl 
propionate and having a molecular weight of from 500 to 5,000. 
Furthermore, GB 2 095 698 discloses that a combination of the stated 
copolymers with amides of long-chain chain amines and aromatic or 
cycloaliphatic carboxylic acids can be added to middle distillates. 
However, these mixtures are still unsatisfactory with regard to the 
dispersing properties of the paraffin which has separated out. 
It is therefore necessary that the additives introduced also disperse the 
paraffin which has separated out. 
EP 398 101-A discloses reaction products of aminoalkylenepolycarboxylic 
acids with long-chain secondary amines, which have been completely 
converted with the sine to the amide or ammonium salt, as paraffin 
dispersants. To achieve good dispersing of the paraffins which have 
separated out by means of these products, however, frequently from 0.25 to 
40 ppm of a conductivity improver have to be added to the diesel fuel, in 
addition to the dispersant. 
However, the introduction of a further additive is disadvantageous for 
production and is expensive. Furthermore, admixing a conductivity improver 
may be ecologically disadvantageous, 
It is an object of the present invention to provide paraffin dispersants 
for mineral oil middle distillates, which dispersants have an excellent 
dispersing effect even without additional conductivity improvers. 
We have found that this object is achieved by mineral oil middle distillate 
compositions based on a hydrocarbon mixture whose boiling range begins at 
above 160.degree. C. and ends at below 420.degree. C., containing an 
amount, effective as a paraffin dispersant, of compounds of the formulae I 
and/or II 
##STR1## 
where 
A is straight-chain or branched alkylene of 2 to 6 carbon atoms or a 
radical of the formula III 
##STR2## 
--OH and/or --O.crclbar.M.sym. R.sup.1 is hydrogen or a straight-chain 
aliphatic radical of 10 to 30 carbon atoms, R.sup.2 is a straight-chain 
aliphatic radical of 10 to 30 carbon atoms and M is an alkali metal or 
alkaline earth metal, with the proviso that the following two conditions 
are fulfilled, is. X is 
a) at least one 
##STR3## 
group and b) at least one --OH-- and/or --O.crclbar.M.sym. group. 
Surprisingly, we have found that, when the compounds of the formulae I 
and/or II, i.e. the reaction products of aminoalkylenecarboxylic acids 
(III and IV) 
##STR4## 
where A has the abovementioned meanings, with primary or secondary 
long-chain amines having at least one amide and one carboxyl and/or 
carboxylate group, are used, it is possible to dispense with the addition 
of a conductivity improver in order to obtain the same effects in the 
dispersing of the paraffins which have separated out. 
The novel mineral oil middle distillate compositions thus have improved 
cold flow due to better dispersing of the paraffin crystals which have 
separated out. 
In the compounds of the formulae I and/or II which are used in the mineral 
oil middle distillates, R.sup.1 is preferably hydrogen or R.sup.1 and 
R.sup.2 are each preferably a straight-chain aliphatic radical of 14 to 22 
carbon atoms. Particularly preferably, both R.sup.1 and R.sup.2 are a 
straight-chain aliphatic radical of 10 to 30, in particular 14 to 22, 
carbon atoms, is the amines used for the preparation of the compounds are 
secondary amines. Specific examples of secondary amines are dioleylamine, 
di-tallow fatty amine, dipalmitamine, dicocosamine and dibehenylamine and 
preferably distearylamine or hydrogenated di-tallow fatty amine (the 
latter usually being of 16 to 18 carbon atoms). 
The aminoalkylenepolycarboxylic acid (III, IV) is advantageously reacted 
with the amine in a ratio of from 1:1.5 to 1:3. 
The unconverted carboxyl groups may be present as free carboxylic acids or 
as carboxylates which are formed either by intramolecular neutralization 
with the aminoalkylene groups (betaine formation) or by neutralization 
with metal salts: 
##STR5## 
Compounds of the formula V 
##STR6## 
i.e. where three radicals X are each 
##STR7## 
and one radical X is --OH or --O.crclbar.M.sym., are particularly 
preferred. 
The compounds of the formulae I and II are generally added to the novel 
mineral oil middle distillate compositions in amounts of from 25 to 1,000 
ppm, preferably from 50 to 500 ppm. 
The middle distillates usually contain conventional flow improvers which 
are described in detail in the patent literature, for example in DE 19 14 
756 and DE 40 36 227 (ethylene/vinyl ester copolymers and mixtures thereof 
with other copolymers), EP 214 876 (.alpha.-olefin/maleic anhydride ester) 
or EP 155 807 (alkyl fumarate/vinyl acetate copolymers). 
However, terpolymers which, in addition to ethylene and vinyl esters or 
acrylates, also contain further comonomers are also suitable. The 
molecular weight of these flow improvers is as a rule from 500 to 5,000, 
preferably from 1,000 to 3,000. 
Mixtures of different flow improvers are also suitable.

EXAMPLES 
A) Synthesis of the aminoalkylenepolycarboxamides PD1: Preparation of the 
trisamide of ethylenediaminetetraacetic acid and distearylamine: 1,010.2 g 
(2 mol) of distearylamine PD (hydrogenated ditallow fatty amine) are 
melted, and 6 g of p-toluenesulfonic acid and 194.6 g (0.67 mol) of 
ethylenediaminetetraacetic acid are added. 
The reaction mixture is heated to 190.degree. C. and is condensed for 3 
hours at this temperature. The product is then filtered while hot. 1,180 g 
of a brown solid having an acid number of 33 mg KOH/g are obtained. PD2: 
Preparation of the calcium salt of PD1 
101 g (0.2 mol) of PD1) are melted, and 14.8 g of calcium hydroxide are 
added. Heating is carried out for 2 hours at 100.degree. C., after which 
the product is filtered. About 110 g of a brown solid are obtained. 
B) Testing of the mineral oil middle distillate compositions 
Description of the test method: 
Various amounts of paraffin dispersants PD 1, PD 2 and PD 3 and/or flow 
improvers F1, and if necessary also conductivity improvers CI (E) 
(comparison), were added to the middle distillates at 40.degree. C. while 
stirring, after which the mixture was cooled to room temperature. 
The additive-containing middle distillates were stored in 100 ml measuring 
cylinders for 20 hours in a refrigerator at -13.degree. C. Thereafter, the 
volume of the paraffin phase which had settled out (% by volume) was 
visually estimated and the appearance of the oil phase was assessed. 
The following mineral oil middle distillate compositions were tested: 
Mineral oil middle distillate compositions containing 
1 ) as a paraffin dispersant PD 1, PD 2 ethylenediaminetetraacetic acid 
derivatives according to A), 
2) as flow improver Fl 1 ethylene/vinyl propionate, containing about 40% by 
weight of vinyl propionate and having an average molecular weight of about 
2,500 
C) Mineral oil middle distillate compositions (comparison according to EP 
398 101) containing 
1) as a paraffin dispersant PD 3 nitriloacetamide A) 1 from EP 398 101 
2) as flow improver Fl 1 ethylene/vinyl propionate, containing about 40% by 
weight of vinyl propionate and having an average molecular weight of about 
2,500 
3) as conductivity improver CI (E) from EP 398 101 
Diesel fuels of commercial German refinery quality were used as middle 
distillates for the following dispersion tests; they are referred to as DK 
1, DK 2 and DK 3: 
______________________________________ 
DK 1 DK 2 DK 3 
______________________________________ 
Cloud point CP (.degree.C.) 
-8 -8 -7 
CFPP (.degree.C.) -13 -12 -10 
Density at 20.degree. C. (g/ml) 
0.827 0.831 0.829 
Beginning of boiling range (.degree.C.) 
165 175 183 
20% boiling point (.degree.C.) 
210 223 211 
90% boiling point (.degree.C.) 
318 314 317 
End of boiling range (.degree.C.) 
358 352 364 
______________________________________ 
The results are shown in Tables 1 to 3. It is evident that the compounds PD 
1 and PD 2 have a better dispersing effect than the compound which is 
disclosed in EP 398 101 which has comparable dispersing effects only in 
the presence of a conductivity improver. 
TABLE 1 
______________________________________ 
DK 1, CP: -8.degree. C., CFPP: -13.degree. C. 
Paraffin 
Appear- 
PD 1 PD 2 PD 3 Fl 1 CI (E) 
sediment 
ance of 
(ppm) (ppm) (ppm) (ppm) (ppm) (% by vol.) 
oil phase 
______________________________________ 
100 -- -- 200 -- 0 dispersed 
-- -- 100 200 1 35 dispersed 
______________________________________ 
TABLE 2 
______________________________________ 
DK 2, CP: -8.degree. C., CFPP: -12.degree. C. 
Paraffin 
Appear- 
PD 1 PD 2 PD 3 Fl 1 CI (E) 
sediment 
ance of 
(ppm) (ppm) (ppm) (ppm) (ppm) (% by vol.) 
oil phase 
______________________________________ 
100 -- -- 300 -- 15 dispersed 
-- 100 -- 300 -- 20 dispersed 
-- -- 100 300 1 30 dispersed 
-- -- 100 300 -- 25 cloudy 
-- -- -- 300 -- 35 clear 
______________________________________ 
TABLE 3 
______________________________________ 
DK 3, CP: -7.degree. C., CFPP: -10.degree. C. 
Paraffin 
Appear- 
PD 1 PD 2 PD 3 Fl 1 CI (E) 
sediment 
ance of 
(ppm) (ppm) (ppm) (ppm) (ppm) (% by vol.) 
oil phase 
______________________________________ 
100 -- -- 300 -- 20 dispersed 
-- 100 -- 300 -- 10 dispersed 
-- -- 100 300 1 15 dispersed 
-- -- 100 300 -- 10 cloudy 
-- -- -- 300 -- 10 clear 
______________________________________