Abstract:
Catalysts are activated in a dual reactor solution process by adding a cocatalyst comprising an alkylaluminoxane and an ionic activator to an organometallic polymerization catalyst in each of a first reactor and a second reactor. The ionic activator is used in substoichiometric and superstoichiometric amounts in the first and second reactors, respectively. The total molar ratio of ionic activator to organometallic catalyst present over both reactors is at least 0.8. The activation method facilitates control over process conditions and gives access to polymer films having improved optical properties.
Abstract:
This invention provides a two stage process for the oligomerization of ethylene in the presence of a chromium catalyst having a bridging diphosphine ligand. The process mitigates problems which may be experienced during the unsteady state conditions that exist during "start up". The "start up" protocol of this process is characterized by the use of an aluminoxane activator and a comparatively large amount of a halogenated solvent. After the start up phase, a second activator (which is preferably a non-coordinating borate) is added to the reaction.
Abstract:
A magnesium titanium olefin polymerization procatalyst is prepared by A) reacting a diorganomagnesium compound with a source of active chlorine, (with the proviso that the amount of chlorine is insufficient to completely convert the diorganomagnesium to magnesium dichloride); then B) removing unreacted diorganomagnesium from the reaction product; then C) adding a tetravalent hafnium species to the washed MgCl2 support; then D) depositing a tetravalent titanium species on the supported Hf. This procatalyst is highly active for the solution polymerization of olefins when combined with a cocatalyst.
Abstract:
A new P-N-P ligand is useful in ethylene oliogomenzation. The ligand is characterized by having at least one aromatic fiuorocarbyl alkoxide group bonded to a P atom, hi combination with 1) a source of chromium and 11) an activator such as methylalumoxane, the ligand of this invention may be used to prepare an oligomer product that contains a mixture of high purity alpha olefins, hi a preferred emobidment, the ligand of this invention enables a selective oligomerization in which the majority of the liquid product is a mixture of hexene and octene. The amount of byproduct polymer that is produced in preferred oligomerization reactions is advantegeously low.
Abstract:
An olefin polymerization catalyst is prepared by (a) in a diluent, combining a diorganomagnesium compound with less than 2 molar equivalents of a first source of chloride to produce a "chloride deficient" magnesium chloride support; (b) without isolating any solids, adding a second source of chloride which reduces the amount of soluble un-reacted diorganomagnesium compound present; (c) without isolating any solids present, adding a tetravalent titanium species and; (d) adding an activator. The catalyst is active for solution polymerization of olefins.
Abstract:
A continuous flow process for the oligomerization of ethylene using a chromium catalyst having a phosphorus - nitrogen - phosphorus ("P-N-P") ligand provides high selectivity to the desired tetramer (1-octene) with reduced production of coproduct C 10+ oligomers. Prior art processes that maximize catalyst activity have provided comparatively poor product selectivity. In particular, the production of larger amounts of C 10+ oligomers have been observed under conditions that maximize activity. The present process resolves this problem through the use of a combination of low catalyst concentration and by limiting the octene concentration in the reactor.
Abstract:
This invention enables the "bulk" oligomerization of ethylene (i.e. the oligomerization of ethylene in the presence of the oligomer product) using a catalyst system comprising 1) a very low concentration of a chromium catalyst and 2) a three part activator. The chromium catalyst contains a diphosphine ligand, preferably a so called P-N-P ligand. The activator includes an aluminoxane, trimethyl aluminum, and triethyl aluminum.