Chemistry of hydrocarbon compounds – Product blend – e.g. – composition – etc. – or blending process... – Component of indefinite molecular weight greater than 150
Reexamination Certificate
1997-12-12
2001-04-24
Lipman, Bernard (Department: 1713)
Chemistry of hydrocarbon compounds
Product blend, e.g., composition, etc., or blending process...
Component of indefinite molecular weight greater than 150
C585S010000, C585S013000, C044S459000
Reexamination Certificate
active
06222081
ABSTRACT:
The present invention relates to liquid hydrocarbons compositions, for instance gasoils, generally known as middle distillates.
It is known that the middle distillates contain alkanes which at low temperatures tend to precipitate under the form of waxes as high size crystals. In this way gel structures are formed which cause the middle distillates fluidity loss. Therefore there are problems of storage, transfer and feeding the middle distillates through pipes, pumps and moreover obstruction phenomena of the line filters and of those of the propulsors feeding lines occur.
These problems are well known in the art and for the definition of cold behaviour, the middle distillates are characterized from the physical point of view with the following features determined according to various standard methods: Cloud Point (C.P.), Pour Point (P.P.), Cold Filter Plugging Point (C.F.P.P.), Wax Antisettling (W.A.S.) etc.
Various additives, some of them in the market, having selective and/or multifunctional uses are known in the art, capable of improving the above mentioned cold features of middle distillates. The additives generally have the purpose of modifying the wax crystals formed at low temperatures both reducing the sizes and modifying the form thereof. Indeed the crystals with reduced sizes give less problems of filters blockage. A further property required by additives is that to maintain in suspension the formed crystals, that is to obtain the result to have a reduced sedimentation rate. Also this effect prevents the filters blockage at low temperatures, particularly it reduces the storage on the tanks bottom during storage of middle distillates in the refinery.
The additives known in the art to overcome such drawbacks are generally polymeric of various types used singly or under the form of physical mixtures.
See for instance the patent application WO 91/11488 which claims the combination of some of the additives mentioned above with (co)polymers of ethylene with alpha-olefins, in particular ethylene/propylene copolymers obtainable by polymerization of ethylene with alpha-olefins in the presence of catalysts based on a) coordination organometallic compounds which are cyclopentadienyl derivatives of a metal of the Group 4b of the Periodic Table and comprise mono-, di-cyclopentadienyl and their derivatives of the transition metal, with b) alumoxanes, which are the reaction products of trialkyl aluminium with water. The ethylene/alpha-olefins copolymers obtained have the essential feature to have at least 30% of the polymeric chains with terminal ethenylidene or ethenyl unsaturations. These copolymers can be combined with one or more additives known in the art having the property of improving the middle distillates characteristics at low temperatures.
Ethylene/alpha-olefins copolymers suitable for the same purposes are also known in the art, see U.S. Pat. No. 5,097,084, which are characterized by the substantial absence of linking inversions of propylene as shown by the parameters X
2
and/or X
4
lower than or equal to about 0.02, determined by
13
C NMR according to the method described by J. C. Randal in “Macro-molecules” 11, 33 (1978). The ethylene/propylene copolymers having said values of the mentioned parameters clearly show better CFPP values than the copolymers in which said values are not present, for instance vanadium-based catalysts.
Copolymers of ethylene or alpha-olefins, or unsaturated esters, for instance vinylacetates, with maleic or fumaric acid, or unsaturated monocarboxylic acid esters, for instance acrylates, are also known in the art. Copolymers of ethylene/vinylacetate (EVA), fumarates, propionates, etc., can be mentioned. See for instance the patents U.S. Pat. No. 3,661,541, U.S. Pat. No. 4,211,534, EP 153,176, EP 153,177. Also various combinations of the described copolymers are indicated in these patents, optionally in combination with a nitrogen polar compound.
It has been surprisingly and unexpectedly found by the Applicant that certain particular ethylene alpha-olefins (co)polymers show improved properties when are used as additives to improve the middle distillates properties at low temperatures. In particular the copolymers of the invention show improved C.F.P.P values.
It is an object of the present invention copolymers of ethylene with one or more alpha-olefins from 3 to 20 carbon atoms, preferably 3 to 8 C, utilizable as additives to improve the middle distillates properties at low temperatures, obtainable by polymerization of the monomers in the presence of catalysts comprising the reaction product among:
1) a bis-cyclopentadienyl derivative of general formula:
(Cp
1
Cp
2
)—M—(L
2
L
3
)
containing groups with oxygen bound to the transition metal, wherein
M is a metal from the group IIIb to the group IIb, preferably IV group, or of the lanthanides series of the Periodic Table; Cp
1
and Cp
2
equal to or different from each other represent the following groups bound to M with delocalized &pgr; bonds, in particular with an eta 5 bond when the groups are chosen from cyclopentadiene, indene, fluorene or derivatives thereof, substituted in the case of indene and fluorene also with the hydrogenated phenyl ring (rings) and with substituents both in phenyl and cyclopentadienyl rings, also with heteroatoms; or with &pgr; bonds for instance in the case of cyclooctatriene; or said groups Cp
1
Cp
2
constrained with M by a bivalent linking bridge, for instance —R— type wherein R is an alkylene, preferably from 1 to 4 carbon atoms, —Si(R′)
2
— wherein R′ is an alkyl from 1 to 10 C atoms, preferably from 1 to 6 carbon atoms; or an aryl optionally containing heteroatoms, such as O, N, or alkylaryl or arylalkyl from 7 to 20 carbon atoms; L
2
or L
3
equal to or different from each other represent a group OR
a
wherein R
a
is an aryl group, optionally the carbon atoms of the ring being substituted by heteroatoms, and optionally containing substituents for instance of alkyl type from 1 to 10 carbon atoms, with
2) a cocatalyst selected from the compounds represented by the following formulas:
2a) alumoxane, having the general formula:
(R
b
—Al—O)
m′
under the form of cyclic compound or under the form of linear polymeric compound of formula
R
b
(R
b
—Al—O)
m
Al(R
b
)
2
;
alumoxane is generally a mixture of the two mentioned forms;
R
b
is an alkylic group from 1 to 5 C atoms, preferably methyl,
m is an integer from 1 to 30, preferably from 4 to 20;
m′ is an integer from 3 to 20, preferably from 4 to 20;
2b) (L
1
—H)
+
(A)
−
wherein (A)
−
is a compatible non coordinate anion, preferably
(B Q
q
)—
wherein L
1
is a neutral Lewis basis,
(L
1
—H)
+
is a Bronsted acid,
B is an element of the group from IIIa up to VIa of the Periodic Table with metalloidic characteristics, preferably boron, phosphor or arsenic in the valence 3 or 5, silicon, more preferably boron in the valence 3;
Q, equal to or different from each other, are chosen from the following groups: hydrides, halides, alkyls, aryls optionally substituted, for instance with halogens, preferably F, alkoxides, aryloxides, dialkylamido, or R
0
COO— wherein R
0
ranges from 1 to 20 carbon atoms, with the proviso that Q can be equal to halide only once,
q is an integer equal to the valence of B plus 1. The preferred co-catalyst component 2) is 2b).
The alumoxane compound 2a) of the catalytic system is preferably prepared by reaction of trimethyl aluminium and water, obtaining a mixture of linear and cyclic compounds. They are generally prepared by putting into contact a solution of trialkyl aluminium with water in suitable organic solvents, for instance aliphatic hydrocarbons.
As known, aluminoxanes are compounds containing Al—O—Al bonds, having molar ratio ranging between O/Al, obtainable in the art by reaction, under controlled conditions, of an alkyl aluminium, or alkyl aluminium halide, with water and, in the case of trimethyl aluminium, also with an hydrate salt, such as hexahydrate aluminium sulphate, pentahydrate copper sulphate and pentahydrate iron sulphate.
Burton Jeremy
Falchi Paolo
Fox Arent
Kintner Plotkin Kahn PLLC
Lipman Bernard
Rabago R.
Societa' Italiana Additivi Per Carburanti S.r.l.
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