Oil composition

Details Oil composition Oil composition

2002-12-18

2004-11-23

Toomer, Cephia D. (Department: 1714)

Fuel and related compositions

Liquid fuels

Heterocyclic carbon compound containing a hetero ring having...

C044S348000

Reexamination Certificate

active

06821307

ABSTRACT:

This invention relates to improved detergent and lubricity additives for fuel oils.
The art generally describes additives derived from hydrocarbyl-substituted succinic acylating agents (such as succinic anhydrides) and polyalkylene polyamines. These materials are sometimes known as ‘succinimides’ or ‘acylated nitrogen dispersants’ Particularly well-known are those materials wherein the succinic substituent is derived from polyisobutylene, the resulting materials being commonly known as ‘PIBSA-PAM’ (Polyisobutylene-succinic anhydride-polyamine) products.
The trivial name of ‘succinimides’ is, for many of these products, rather an oversimplification. The commercially-available materials used to make these products are typically complex mixtures rather than discrete compounds, and thus give rise to a complex mixture of other condensation products in addition to various imides.
EP-B-0 451 380 provides a broad general description of PIBSA-PAM products and illustrates the complex nature of many polyamine mixtures. The examples are restricted to PIBSA-PAM products obtained from polyethylene tetramine or pentamine at molar ratios of 1.5:1 or greater (PIBSA:PAM).
With such variability in products produced from different sources of starting materials, there exists in the art a continual need for better understanding of the molecular parameters controlling various aspects of additive performance, and for better-performing, more cost-effective products
Surprisingly, it has now been found that by selecting a certain mole ratio of reactants and certain polyamine characteristics, products having improved go application specifically in fuel oils are obtained.
In a first aspect, the invention provides a fuel oil composition comprising a fuel oil and a minor proportion of an additive, wherein the additive comprises the product obtainable by the reaction between
(i) a hydrocarbyl-substituted succinic acylating agent, wherein the hydrocarbyl substituent has a number-average molecular weight (Mn) of 250 to 2500, and
(ii) one or more polyalkylene polyamines,
characterised in that the polyamine component (ii) contains greater than 35% by weight of polyamines having more than six nitrogen atoms per molecule, based on the total weight of polyamines, and in that (i) and (ii) are reacted in a molar ratio in the range of 1.4:1 to 1:1 ((i):(ii)).
In a second aspect, the invention provides the additive as defined under the first aspect.
In a third aspect, the invention provides the use of the additive of the second aspect as a detergent and/or lubricity improver in a fuel oil.
When used in a fuel oil, and especially a middle distillate fuel oil, the additive according to the invention provides surprisingly-improved fuel detergency, especially in fuel oil systems such as diesel fuel engines where improved fuel injector detergency is observed. In addition, the additive can provide lubricity improvement for fuel oils, a property of increasing usefulness especially in middle distillate fuels as incremental legislative changes force down the level of sulphur of such fuels, leading to fuel processing and compositional changes which reduce the fuels' inherent lubricity properties. Such lubricity enhancement is particularly effective in inhibiting wear in the fuel injection pumps of diesel engine systems which, due to engineering developments aimed at reducing emissions, are being designed to operate at increasingly high pressures and are therefore more prone to wear
These improvements in performance are believed to result from the optimised structure of the product defined under the first aspect of the invention Without being bound to any particular theory, it is thought that the combination in the product of a polyalkylene polyamine having a high proportion of heavy (i.e. higher molecular weight) components, and a relatively low average molar ratio of acylating agent (i) to polyamine (ii), gives rise to products having a balance of polar and non-polar groups which is particularly effective in the fuel oil environment.
The First Aspect of the Invention
The Product
The product is preferably obtained by the reaction of (i) and (Ii) as above defined.
(i) The Hydrocarbyl-Substituted Succinic Acylating Agent
The term hydrocarbyl denotes a group having a carbon atom directly attached to the remainder of the molecule and which has a predominantly aliphatic hydrocarbon character. Therefore, hydrocarbyl substituents can contain up to one non-hydrocarbyl group for every 10 carbon atoms provided that this non-hydrocarbyl group does not significantly alter the predominantly aliphatic hydrocarbon character of the group. Those skilled in the art will be aware of such groups, which include, for example, hydroxyl, halo (especially chloro and fluoro), alkoxyl, alkyl mercapto, alkyl sulfoxy, etc. Usually, however, the hydrocarbyl substituents are purely aliphatic hydrocarbon in character and do not contain such groups.
The hydrocarbyl substituents are predominantly saturated. The hydrocarbyl substituents are also predominantly aliphatic in nature, that is, they contain no more than one non-aliphatic moiety (cycloalkyl, cycloalkenyl or aromatic) group of 6 or less carbon atoms for every 10 carbon atoms in the substituent. Usually, however, the substituents contain no more than one such non-aliphatic group for every 50 carbon atoms, and in many cases, they contain no such non-aliphatic groups at all; that is, the typically substituents are purely aliphatic. Typically, these purely aliphatic substituents are alkyl or alkenyl groups.
The hydrocarbyl substituents preferably average at least 30 to 50 and up to about 100 carbon atoms, corresponding to an Mn of approximately 400 to 1500 such as 550 to 1500, and preferably 700 to 1500. An Mn of 700 to 1300 is preferred.
Specific examples of the predominantly saturated hydrocarbyl substituents containing an average of more than 30 carbon atoms are the following: a mixture of poly(ethylene/propylene) or poly(ethylene/butene) groups of about 35 to about 70 carbon atoms: a mixture of poly(propylene/1-hexene) groups of about 80 to about 100 carbon atoms: a mixture of poly(isobutene) groups having an average of 50 to 75 carbon atoms; a mixture of poly (1-butene) groups having an average of 50-75 carbon atoms.
A preferred source of the substituents are poly(isobutene)s, for examples those obtained by polymerization of a C4 refinery stream having a butene content of 35 to 75 weight percent and isobutene content of 30 to 60 weight percent in the presence of a Lewis acid catalyst such as aluminium trichloride or boron trifluoride. These polybutenes predominantly contain isobutene monomer repeating units of the configuration
—C(CH
3
)
2
CH
2
—
The hydrocarbyl substituent is attached to the succinic acid moiety or derivative thereof via conventional means, for example the reaction between maleic anhydride and an unsaturated substituent precursor such as a polyalkene, as described for example in EP-B-0 451 380.
One procedure for preparing the substituted succinic acylating agents involves first chlorinating the polyalkene until there is an average of at least about one chloro group for each molecule of polyalkene. Chlorination involves merely contacting the polyalkene with chlorine gas until the desired amount of chlorine is incorporated into the chlorinated polyalkene. Chlorination is generally carried out at a temperature of about 75° C. to about 125° C. If desired, a diluent can be used in the chlorination procedure. Suitable diluents for this purpose include poly- and perchlorinated and/or fluorinated alkanes and benzenes.
The second step in the procedure is to react the chlorinated polyalkene with the maleic reactant at a temperature usually within the range of about 100° C. to about 200° C. The mole ratio of chlorinated polyalkene to maleic reactant is usually about 1:1. However, a stoichiometric excess of maleic reactant can be used, for example, a mole ratio of 1:2 If an average of more than about one chloro group per molecule of polyalkene is introduced during the chlorination step, then

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