Chemistry of hydrocarbon compounds – Product blend – e.g. – composition – etc. – or blending process... – Component of indefinite molecular weight greater than 150
Reexamination Certificate
1999-06-09
2001-08-21
Howard, Jacqueline V. (Department: 1764)
Chemistry of hydrocarbon compounds
Product blend, e.g., composition, etc., or blending process...
Component of indefinite molecular weight greater than 150
C585S014000, C044S314000, C044S317000
Reexamination Certificate
active
06278032
ABSTRACT:
The present invention relates to liquid hydrocarbon compositions, for instance gas oils, generally known as middle distillates.
It is well 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 distillate fluidity loss. Therefore there are problems of storage, transfer and feeding of 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 cold behaviour definition, the middle distillates are characterized from the physical point of view by 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, able to improve the above mentioned middle distillate cold propoerties. The additives generally have the purpose to modify the wax crystals formed at low temperatures both reducing the size and modifying the form thereof.
Indeed the crystals having reduced size give less problems of filter clogging. A further property required to additives is that to maintain in suspension the formed crystals, that is to obtain the result to have a reduced settling rate. Also this effect prevents the filter clogging at low temperatures, particularly it reduces wax accumulations on the tank bottom during storage of middle distillates in the refinery.
The additives known in the art to overcome such disadvantages are generally polymeric products of various types.
See for example Patent Application WO 91/11488 which claims the combination of some of the above mentioned additives with ethylene (co)polymers with alpha-olefins, specifically 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 transition metal of the Group 4b of the Periodic Table and comprise mono-, di- and tri-cyclopentadienyl and their derivatives of the transition metal, with b)
alumoxanes, which are the reaction products of trialkyl aluminum with water.
The obtained ethylene/alpha-olefin copolymers have the essential feature to have at least 30% of the polymeric chains with ending ethenylidene or ethylene unsaturations. These copolymers can be combined with one or more additives known in the art having the property to improve the middle distillate characteristics at low temperatures.
Ethylene/alpha-olefin (co)polymers used for the same purpose are also known in the art, see U.S. Pat. No. 5,097,084. They are characterized by the substantial absence of propylene linking inversions as shown by the X
2
and/or X
4
parameters lower than or equal to about 0.02, determined by
13
C NMR according to the method described by J. C. Randal in “Macromolecules” 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 satisfied, for instance the vanadium-based catalysts.
Ethylene or alpha-olefin copolymers, 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. Ethylene/vinylacetate (EVA) copolymers, fumarates, propionates, etc., can be mentioned. See for instance U.S. Pat. No. 3,661,541, U.S. Pat. No. 4,211,534, EP 153,176, EP 153,177. Various combinations of the described copolymers are indicated too in these Patents, optionally in combination with a nitrogen polar compound.
It has been surprisingly and unexpectedly found by the Applicant that specific copolymers of ethylene with octene and/or terpolymers of ethylene, octene with at least an alpha-olefin show improved properties when are used as additives to improve the middle distillate physical behaviour at low temperatures. In particular the invention polymers show improved C.F.P.P values.
It is an object of the present invention copolymers of ethylene with octene and/or terpolymers of ethylene, octene with at least an alpha-olefin having from 3 to 12 carbon atoms, optionally in the presence of other comonomers containing more than one ethylenic unsaturation, usable as additives to improve the middle distillate 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 Vb or of the lanthanide series of the Element 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 selected 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 example in the case of cyclooctatriene; or said Cp
1
Cp
2
groups constrained with M by a bivalent linking bridge, for example —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
and L
3
equal to or different from each other represent a group OR
a
wherein R
a
is an aryl group, optionally the ring carbon atoms being substituted also by heteroatoms, and optionally containing substituents for example 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′
in the form of cyclic compound or in 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 alkyl 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 coordinating 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 Element Periodic Table with metalloidic characteristics, preferably boron, phosphorus or arsenic with valence 3 or 5, silicon, more preferably boron with valence 3;
Q, equal to or different from each other, are selected from the following groups: hydrides, halides, alkyls, aryls optionally substituted, for example 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 aluminum and water, obtaining a mixture of linear and cyclic compounds. They are generally prepared by putting into contact a solution of trialkyl aluminum with water in suitable organic solvents, for instance aliphatic hydrocarbons.
As known, alumoxanes are compounds containing Al—O—Al bonds, having a variable O/Al molar ratio, obtainable in the art by reaction, under controlled conditions, of an alkyl aluminum, or an alkyl aluminum halide, with water and, in the cas
Arent Fox Plotkin Kintner Kahn PLLC.
Howard Jacqueline V.
Societa' Italiana Additivi Per Carburanti S.r.l.
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