Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Primarily organic continuous liquid phase
Reexamination Certificate
1998-03-09
2001-01-30
Lovering, Richard D. (Department: 1764)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Primarily organic continuous liquid phase
C208S039000, C208S0480AA, C507S090000, C516S916000
Reexamination Certificate
active
06180683
ABSTRACT:
Asphaltenes are constituents of crude oils. They comprise a large number of structures, in particular high molecular weight fused aromatic components containing heteroatoms. In view of the complexity of their chemistry, asphaltenes are described as the oil fraction which is soluble in benzene, but not in n-pentane.
In crude oil, asphaltenes are usually in the form of a colloidal dispersion. This is stabilized by oil resins.
Asphaltenes can precipitate out during the production, refining, transportation and storage of crude oil and products derived therefrom, such as, for example, heavy heating oil or marine oil. Common causes of this precipitation are a reduction in the temperature or a change in the composition (for example evaporation of readily volatile constituents). Asphaltenes can also precipitate out on flowing through porous media. Flooding with CO
2
during the extraction process can make asphaltenes flocculate or precipitate out.
Some oils comprise hydrocarbon waxes which precipitate out at low temperatures. Interactions between the wax precipitates and asphaltenes can increase the total amount of substance precipitated out or the rate of formation thereof.
Asphaltenes which have precipitated out cause problems during the production and processing of crude oils. Asphaltenes are precipitated in valves, pipes and conveying devices. On hot surfaces, such as, for example, heat exchangers, carbonization of these precipitates can make their removal very difficult. The precipitates reduce the efficiency of plants and in the worst case can lead to complete blockage and to a stop in production, which results in high costs.
Heavy oils, which are often used for powering ships, comprise considerable amounts of asphaltenes. The precipitating out of asphaltenes can lead both to poor combustion and to difficulties in the handling and storage of the fuel.
Bitumen, heavy oils and residues are sometimes diluted with solvents to reduce the viscosity for transportation. If asphaltenes precipitate out here, problems arise in handling.
The precipitating out of asphaltenes can be prevented or reduced by small amounts of dispersants. These substances show one or more of the following effects:
a) the amount of precipitate is reduced;
b) the precipitate forms more slowly;
c) the precipitate is more finely divided; and
d) the tendency of the precipitate to be deposited on surfaces is reduced.
If precipitates of asphaltenes have already formed, they can be removed by using solvents. The addition of a dispersant can improve the effectiveness of these solvents.
A large number of asphaltene dispersants are already known. CA 2, 029, 465 and CA 2, 075, 749 describe alkylphenol-formaldehyde resins in combination with hydrophilic-lipophilic vinyl polymers. The asphaltene-dispersing properties of dodecylbenzenesulfonic acid have been described in U.S. Pat. No. 4,414,035, and also by D. -L. Chang and H. S. Fogler (SPE paper No. 25185, 1993) and by M. N. Bouts et al. (J. Pet. Technol. 47, 782-7, 1995).
The preparation of oxalkylated amines and their use as corrosion inhibitors, demulsifiers and paraffin dispersants is described in U.S. Pat. No. 5,421,993. Alkylphenol-formaldehyde resins can be prepared by acidic or basic catalysis. Compounds prepared by acidic catalysis are predominantly linear (cf. formula I), whilst compounds prepared by basic catalysis have a high content of cyclic material, as in Formula II (see B. Rowan in D. Karsa (editor) “Industrial application of surfactants III”, p. 247).
The dispersants known to date are able to solve only partially the problems caused by the precipitating out of asphaltenes. Since oils vary in their composition, individual dispersants can only be effective in a limited range. Even small changes in the composition of the oil sometimes have a great effect on the dispersing properties of asphaltenes. In some cases, therefore, the known dispersants are unsatisfactory and additional types are required.
The object was, therefore, to provide novel asphaltene dispersants which do not have the disadvantages described of the dispersants known to date.
It has now been found that combinations of alkylphenol resins and oxalkylated amines have a stronger asphaltene-dispersing effect than the individual substances. This synergy is surprising since a reduction in the effectiveness would be expected in this type of combination of acidic and basic compounds as a consequence of partial neutralization.
The invention therefore relates to a synergistic mixture comprising
from 5 to 95% by weight, preferably from 20 to 80% by weight, of a compound A of the formula (I) or (II)
where
n is from 2 to 12, preferably from 5 to 9, and
R is C
3
-C
24
-alkyl, preferably C
4
-C
12
-alkyl, in particular isononyl, isobutyl or amyl, C
6
-C
12
-aryl or -hydroxyaryl or C
7
-C
12
-aralkyl
and
from 5 to 95% by weight, preferably from 20 to 80% by weight, of a compound B of the formula (III)
in which
x and y, independently of one another, are a number from 0 to 120, preferably from 5 to 80, the sum x+y being at least 5,
z is 1, 2, 3 or 4, preferably 4,
R
1
is hydrogen or methyl,
A′ is a radical of the formulae (IV) to (VII), preferably (VII)
where
R
2
is a C
6
-C
22
-alkyl radical, preferably a C
6
-C
18
-alkyl radical, and
m is 2, 3 or 4; preferably 2 or 3.
Mixtures which are particularly suitable are those in which component A is an isononylphenol-formaldehyde resin or an isononyl/isobutylphenol-formaldehyde resin and component B is an oxalkylated star-shaped amine of the formula (III), in which
A′ is a radical of the formula (VII),
z is 4,
R
2
is C
12
-C
14
-alkyl,
m is 3 and
x and y, independently of one another, are a number from 0 to 60, the sum x+y being at least 5.
The invention further relates to crude oils and products derived therefrom comprising, as asphaltene dispersant, a synergistic combination of alkylphenol resins with oxalkylated amines, as described above.
Products derived from crude oil are, for example, heavy heating oil, marine oil or bitumen.
The oxalkylated fatty amines and fatty amine derivatives of the formula (III) are prepared by customary oxalkylation processes, which involve reacting an amine of the formula (IV) to (VII) with ethylene oxide alone (R
1
is H and the polyoxyalkylene radical consists of ethylene oxide units) or with propylene oxide alone (R
1
is CH
3
and the polyoxalkylene radical consists of propylene oxide units) or with ethylene oxide and propylene oxide simultaneously or successively (R
1
is H and CH
3
and the polyoxalkylene radical consists of ethylene oxide and propylene oxide units which are randomly distributed or in block form). The reaction is generally carried out at a temperature of from 100 to 180° C., in the absence or presence of an alkaline or acidic oxalkylation catalyst, with exclusion of air.
The amine compounds of the formula (III) and their preparation are described in detail in U.S. Pat. No. 5,421,993, which was cited at the beginning and which is expressly incorporated herein by way of reference. They are obtained by oxalkylation of amines of the formulae (IV) to (VII) defined above, firstly using ethylene oxide and then using propylene oxide, with the addition of bases, such as alkali metal hydroxides. The reaction is carried out in stages at a temperature of, preferably, from 100 to 160° C. The amount of catalyst/base used is generally from 0.5 to 3.0% by weight, based on the starting amine used. The molar amount of ethylene oxide and propylene oxide per mole of starting amine corresponds to the values specified for x and y. Reference is made to the cited U.S. Pat. No. 5,421,993 for details.
The compound of the formula (I) or (II) can be neutralized completely or partially using NaOH, KOH, NH
3
or amine. Both the acidic and the neutralized forms are effective.
For some oils, an acidic asphaltene dispersant is advantageous. This can be achieved by adding acids, such as, for example, acetic acid. Particularly suitable acids are organic acids having surfactant properties, such as mono- or dialkylbenzen
Feustel Michael
Hoffmann Dieter
Miller Dennis
Vollmer Axel
Vybiral Reinhard
Clariant GmbH
Dearth Miles B.
Hanf Scott E.
Lovering Richard D.
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