Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By addition of entire unsaturated molecules – e.g.,...
Reexamination Certificate
2002-02-22
2004-08-17
Dang, Thuan D. (Department: 1764)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By addition of entire unsaturated molecules, e.g.,...
C585S512000, C585S513000
Reexamination Certificate
active
06777584
ABSTRACT:
The present invention generally relates to a novel process for selective coupling of terminal olefins with ethylene to manufacture linear &agr;-olefins in the presence of organometallic coupling catalysts.
BACKGROUND OF THE INVENTION
Linear &agr;-olefins are versatile intermediates and building blocks for the chemical industry. Their main applications are as comonomers for polyethylene (C
4
-C
8
), feedstock for surfactants (C
12
-C
20
), and plasticizers (C
6
-C
10
). Hydrocarboxylation of the C
6
-C
8
&agr;-olefins with cobalt-carbonyl/pyridine catalysts gives predominantly linear carboxylic acids. The acids and their esters are used as additives for lubricants. The C
6
-C
10
&agr;-olefins are hydroformylated to odd-numbered, linear primary alcohols, which are converted to surfactants or to polyvinyl chloride (PVC) plasticizers with phthalic anhydride. Oligomerization of (preferably) 1-decene using BF
3
catalysts gives oligomers that are used as synthetic lubricants, which are known as poly-&agr;-olefins (PAO) or synthetic hydrocarbons. The C
10
-C
12
&agr;-olefins can be epoxidized by peracids; this opens up a route to bifunctional derivatives or ethoxylates as nonionic surfactants.
&agr;-Olefins are produced worldwide at a rate of ca. 4×10
9
lb/year, predominantly through oligomerization of ethylene because of the high product quality and the good availability of ethylene. [Vogt, D. In
Applied Homogeneous Catalysis with Organometallic Compounds
; Cornils, B., Herrmann, W. A., Eds: VCH Publishers: 1996; Vol. 1: pp 245-256. (b) Parshall, G. W.; Ittel, S. D. In
Homogeneous Catalysis: The Applications and Chemistry of Catalysis by Soluble Transition Metal Complexes
; John Wiley & Sons: New York, 1992; pp 68-72. (c) Skupinska,
J. Chem. Rev.
1991, 91, 613]. Current industrial commercial processes give &agr;-olefins with a Schulz-Flory distribution, wherein the S-F constant is calculated from the ratio C
n+2
to C
n
compounds in the product mixture, also known as the chain growth factor (&agr;). Other routes to &agr;-olefins in decreasing importance are paraffin wax cracking, paraffin dehydrogenation, and alcohol dehydration.
The wide application and increasing need for &agr;-olefins, as comonomers for polyolefins will cause the linear olefin market to grow. Linear &agr;-olefins are very versatile intermediates and building blocks for the chemical industry. The lower C
4
-C
8
&agr;-olefins are mainly used as comonomers for polyethylene. Small amounts of up to 3% &agr;-olefins are used to produce high-density polyethylene (HDPE) with a higher environmental stress/crack resistance and a slightly reduced density (0.959-0.938 g/cm
3
) compared with the homopolymer (0.965-0.955 g/cm
3
). Higher quantities of 4-12% &agr;-olefins are added to produce linear low density polyethylene (LLDPE) with considerably reduced density (0.935-0.915 g/cm
3
), for which 1-butene and 1-hexene are preferred in the gas-phase process and 1-octene in the liquid phase. [Vogt, D.
Applied Homogeneous Catalysis with Organometallic Compounds
. Cornils, B.; Herrmann, W. A. Eds. VCH Publications, New York. 1996, p. 220.]
Other applications for &agr;-olefins include feedstocks for surfactants (C
12
-C
20
) and plasticizers (C
6
-C
10
). Hydrocarboxylation of the C
6
-C
8
&agr;-olefins with cobalt carbonyl/pyridine catalysts gives predominantly linear carboxylic acids. The acids and their esters are used as additives for lubricants. The C
6
-C
10
&agr;-olefins are hydroformylated to odd-numbered linear primary alcohols, which are converted to polyvinyl chloride (PVC) plasticizers with phthalic anhydride. Oligomerization of (preferably) 1-decene, applying BF
3
catalysts, gives oligomers used as synthetic lubricants known as poly-&agr;-olefins (PAO) or synthetic hydrocarbons. The C
10
-C
12
&agr;-olefins can be epoxidized by peracids; this opens up a route to bifunctional derivatives or ethoxylates as nonionic surfactants. Two basic reactions are commercially used to produce &agr;-olefins. The first is based on the Aufbau reaction which oliogmerizes ethylene by the action of a trialkylaluminum. Two variations are practiced commercially. The first variation is a two-step process in which the chain-growth reaction is first accomplished at about 100° C. and 10 MPa ethylene pressure. In the following high-temperature elimination step, the &agr;-olefins are displaced by ethylene at about 300° C. and 1 MPa. In this stoichiometric reaction sequence, a Poisson distribution of &agr;-olefin products is obtained. The main disadvantage of this process is the large amount of aluminum alkyls needed in an industrial plant. To overcome this drawback, the following processes were developed.
An alternative process based on the Aufbau principle uses a one-step catalytic procedure, where chain growth and elimination occur simultaneously in the same reactor. About 0.4% wt. of AlEt
3
(with respect to ethylene reacted) is needed. For this process solvent heptane is used, at about 200° C. and 25 MPa ethylene pressure. After the reaction, the catalyst is destroyed by hydrolysis. In this catalytic reaction, a Schulz-Flory distribution of &agr;-olefin is obtained.
A variation of this second method is based on a combination of stoichiometric and catalytic chain-growth reactions. Unifying these two parts with a transalkylation step allows very efficient control of the &agr;-olefin chain lengths. The first oligomerization step uses a catalytic one-step process similar to the first process. The process is operated at 160-275° C. and 13-27 MPa of ethylene pressure. After the reaction, the catalyst is destroyed by hydrolysis.
The product mixture, consisting mainly of C
4
-C
10
&agr;-olefins, is distilled and separated into the C
4
-C
10
and C
12
-C
18
fractions. The latter can be used directly. The lower &agr;-olefins are subjected to transalkylation with higher aluminum alkyls, liberating the higher &agr;-olefins. The higher aluminum alkyls are produced in the stoichiometric part of the reaction, operating at about 100° C. and 20 MPa. In the second distillation, the liberated olefins are separated from the aluminum alkyls. These alkyls are fed into a chain-growth reactor, where they are grown with ethylene to long-chain aluminum alkyls, which are recycled to the transalkylation stage. Because of the recycle, co-oligomerization of product &agr;-olefins with ethylene yields considerable amounts of branched olefins. The higher molecular weight C
6
-C
18
fraction, especially, consists of only 63% linear &agr;-olefins. The problem associated with both of the aforementioned processes is that they are done under stoichoimetric conditions and exhibit very low yields of &agr;-olefins.
Another commercially available process is based upon the second basic reaction and produces poly-&agr;-olefins by the oligomerization of ethylene. This process is known as the Shell Higher Olefin Process (SHOP). Catalysts used in this process are neutral Ni(II) complexes bearing bidentate monoanionic ligands [(a) Peuckert, M.; Keim, W.
Organometallics
1983, 2, 594. (b) Keim, W.; Behr, A.; Limbacker, B.; Kruger, C.
Angew. Chem. Int. Ed. Engl.
1983, 22, 503. (c) Keim, W.; Behr. A.; Kraus, G.
J. Organomet. Chem.
1983, 251, 377. (d) Peuckert, M.; Keim, W.
J. Mol. Catal.
1984, 22, 289. (e) Keim, W.; Schulz, R. P.
J. Mol. Catal.
1994, 92, 21]. This ethylene oligomerization process combines oligomerization of ethylene, isomerization of the higher &agr;-olefin products and the metathesis of these internal olefins with butenes or ethylene. It was designed to meet the market need for linear &agr;-olefins for detergents. The nickel catalyst is prepared in situ from a nickel salt, e.g., nickel chloride, and a chelating phosphorus oxygen ligand like o-diphenylphosphinobenzoic acid. The nickel catalyst oligomerizes ethylene in toluene at 80° C. and 5 MPa to 99% linear olefins with 98% &agr;-olefins. The &agr;-olefins produced have a Schulz-Flory type of distribution over the whole range from C
4
-C
30
+
.
Problems
Patil Abhimanyu Onkar
Shaffer Timothy Daniel
Zushma Stephen
Bakun Estelle C.
Dang Thuan D.
ExxonMobil Research and Engineering Company
Wang Joseph C.
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