Fuel and related compositions – Liquid fuels – Containing organic -c
Reexamination Certificate
1998-12-16
2001-07-03
Medley, Margaret (Department: 1714)
Fuel and related compositions
Liquid fuels
Containing organic -c
C044S406000
Reexamination Certificate
active
06254651
ABSTRACT:
This invention relates to oil compositions, primarily to fuel oil compositions, and more especially to fuel oil compositions susceptible to wax formation at low temperatures, to additives for use with such fuel oil compositions, and to processes for the manufacture of the additives.
Fuel oils, whether derived from petroleum or from vegetable sources, contain components, e.g., alkanes, that at low temperature tend to precipitate as large crystals or spherulites of wax in such a way as to form a gel structure which causes the fuel to lose its ability to flow. The lowest temperature at which the fuel will still flow is known as the pour point.
As the temperature of the fuel falls and approaches the pour point, difficulties arise in transporting the fuel through lines and pumps. Further, the wax crystals tend to plug fuel lines, screens, and filters at temperatures above the pour point. These problems are well recognized in the art, and various additives have been proposed, many of which are in commercial use, for depressing the pour point of fuel oils. Similarly, other additives have been proposed and are in commercial use for reducing the size and changing the shape of the wax crystals that do form. Smaller size crystals are desirable since they are less likely to clog a filter. The wax from a diesel fuel, which is primarily an alkane wax, crystallizes as platelets; certain additives inhibit this and cause the wax to adopt an acicular habit, the resulting needles being more likely to pass through a filter than are platelets. The additives may also have the effect of retaining in suspension in the fuel the crystals that have formed, the resulting reduced settling also assisting in prevention of blockages.
Effective wax crystal modification (as measured by cold filter plugging point (CFPP) and other operability tests, as well as simulated and field performance) is achieved by ethylene-vinyl acetate (EVAC) or propionate copolymer-based flow improvers.
The present invention provides the use, to improve cold flow characteristics of an oil, of a compound of the formula
(R
1
R
2
N)m—A—(NR
1
R
3
)
n
I
a
or
BNR
1
2
I
b
wherein
A represents an (m+n) valent and B represents a monovalent hydrocarbon radical optionally interrupted by at least one heteroatom selected from oxygen and nitrogen, each R
1
independently represents
—CHR
4
(CHR
5
)
p
COOR
6
II
R
2
and R
3
each independently represent R
1
, H, or an alkyl group containing from 1 to 8 carbon atoms,
R
4
and R
5
each independently represent H or an alkyl group containing from 1 to 8 carbon atoms,
each R
6
independently represents a hydrocarbyl group, at least one R
6
containing from 8 to 32 carbon atoms optionally interrupted by at least one hetero atom selected from oxygen and nitrogen,
m and n each represent an integer up to 12 or zero provided that the total number of R
1
groups is at least 2, and p represents zero or an integer of 1 to 4.
As used in this specification the term “hydrocarbon” and related terms refer to a group having a hydrocarbon or predominantly hydrocarbon character. Among these, there may be mentioned hydrocarbon groups, including aliphatic (e.g., alkyl), alicyclic (e.g., cycloalkyl), aromatic, aliphatic- and alicyclic-substituted aromatic, and aromatic-substituted aliphatic and alicyclic groups. Aliphatic groups are advantageously saturated. These groups may contain non-hydrocarbon substituents provided their presence does not alter the predominantly hydrocarbon character of the group. Examples include keto, halo, hydroxy, nitro, cyano, alkoxy and acyl. As indicated above, the groups may also or alternatively contain atoms other than carbon in a chain or ring otherwise composed of carbon atoms. Advantageously, except in relation to the oxygen- and nitrogen-interrupted chains represented by A and B and exemplified below, in such an interrupted chain or ring, the carbon:heteroatom ratio is at least 6:1, and is preferably at least 10:1. Advantageously, the hydrocarbon group is linked to the other part or parts of the molecule through a carbon atom.
Advantageously, the hydrocarbon radical represented by A or B has from 1 to 200 carbon atoms, preferably from 2 to 65 carbons, and advantageously from 2 to 60. Preferably, if the hydrocarbon radical is divalent, and uninterrupted, e.g., an alkylene radical, it has up to 16 carbon atoms. If it is interrupted, e.g,. by oxygen atoms, it preferably has from 4 to 60 carbon atoms. Advantageously the radical is a saturated aliphatic radical. Saturated aliphatic radicals may be derived from, for example, ethane, butane, methylene-bis(cyclohexyl), or hexane. Alternatively the radical is an aromatic radical, advantageously one having aliphatic substituents, e.g., one derived from xylene, especially m-xylene, each of the free valencies being attached to a methyl carbon atom.
Examples of hydrocarbons interrupted by nitrogen atoms include 3-azapentane, 3-(2-aminoethyl) azapentane, 3,5-azaoctane, and 3,5,8-azaundecane.
Examples of hydrocarbon radicals interrupted by oxygen atoms include polyoxyalkylene, especially polyoxyethylene and/or propylene, radicals, e.g., those of the formula
—[CH(CH
3
)CH
2
O]
a
—[CH
2
CH
2
O]
b
—[CH
2
CH(CH
3
)O]
c
—CH
2
CH(CH
3
)—, VII
where a+c is advantageously within the range of 2 to 4 and b is advantageously within the range of 5 to 100, and of the formulae
where x+y+z is advantageously within the range of 3 to 100.
Advantageously, R
4
represents hydrogen, and R
5
advantageously represents hydrogen or methyl. Preferably R
4
and R
5
both represent hydrogen.
Advantageously, the hydrocarbyl radical represented by R
6
has from 8 to 32, preferably from 18 to 30, carbon atoms. Advantageously the radical is a saturated aliphatic radical. The radical is preferably a linear alkyl group, or a lightly branched, preferably methyl branched, group, the branch advantageously being near the free end of the chain. The radical may be interrupted by one or more oxygen atoms and, if so interrupted, is advantageously a polyoxyalkylene radical or a polyoxyalkylene-substituted alkyl radical. The radical may be interrupted by one or more nitrogen atoms, and if so interrupted may carry an amino substituent.
The sum of m+n is advantageously such that the total number of R
1
groups is from 2 to 12, preferably from 2 to 6. It will be appreciated from the discussion below of processes for the manufacture of the compounds that, depending inter alia on the proportions and nature of the reactants and the reaction conditions, the number of R
2
and R
3
groups that are substituents of the formula II (i.e., are represented by R
1
) may vary, and that mixtures of compounds in which some groups R
2
and R
3
represent R
1
and others represent hydrogen or an alkyl group may result. It may be advantageous to use a mixture of reactants, e.g., those providing the radicals A and R
6
. Further, since A may represent a radical that is interrupted by nitrogen, the compound may contain additional primary or secondary amine groups. Advantageously, all R
2
and R
3
groups represent R
1
.
The compounds may be manufactured by a number of different processes.
For example, a compound in which p=1 may be made by the esterification of an &agr;, &bgr;-olefinically unsaturated carboxylic acid by a long chain hydroxy compound under esterification conditions that retain the olefinic bond, followed by Michael-type addition of an appropriate polyamine across the double bond. In EP-A0450875, the disclosure of which is incorporated by reference herein, this procedure is refined using a low molecular weight hydroxy compound and subsequently transesterifying with the desired long chain hydroxy compound.
As the unsaturated acid there may be mentioned, more especially, acrylic or methacrylic acid.
As the long chain hydroxy compound, an alkanol, or mixture of alkanols, may be mentioned. The alkanols may be straight or branched chain alkanols, e.g., those containing from 18 to 30 carbon ato
Brooke Barbara Catherine
Tack Robert Dryden
Exxon Chemical Patents Inc.
Medley Margaret
Toomer Cephia D.
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