Note: Descriptions are shown in the official language in which they were submitted.
991~;
712~5-8
This invention relates to the polymerization of
olefins. More particularly, this invention relates to a
process having catalyst compositions which are useful for
polymeriz.ing one or more monomers comprising ethylene to
polymers havlng a na~row molecular weight distributio:n and a
good balance of physical properties.
It is known that catalysts of the type variously
described as coordination, Ziegler, Ziegler-type, or
Ziegler-Natta catalysts are useful for the polymerization of
olefins under moderate conditions at temperature and pressure.
It is also know~ that the properties of the polymers
obtainable by the use of such catalysts, as well as the
relative economies of the processes used to prepare the poly-
mers, vary with several factors, including the choice of
the particular monomers, catalyst components, polymerization
adjuvants, and other polymerization conditions employed.
During the years since Ziegler catalysts were first
publicly disclosedJ there has been a considerable amount of
research conducted on the use of such catalysts; and numerous
publications have resulted from that research. ~hese
publications have added much to the knowledge of how to make
various types of olefin polymers by various types of
processes. However, as is apparent from the amount of
- 2 ~
L2~i3996
11
I research on Ziegler catalysis that is still being conducted
l throughout the world, as well as the number of patents that
¦! are still being issued to lnventors working in the field of
il Ziegler catalysis, the means of attaining certain results
I! when polymerizing olefins with Ziegler catalysts are still
frequently unpredictable. The fact that this situation
exists is sometimes due to the need to obtain a
¦ previously-una-ttainable combination of results; occasionally
due to difficulties in obtainin~ the same results in a
il commercial-scale apparatus as in a laboratory-scale reactor;
¦l and often due to a polymerization parameter's having an
effect, or side-effect, in a given type of polymerization
¦I process that is dlEFerellt Erom effects achieved by its use in
¦I prior art processes of a diEEerent type.
One aspect oE Ziegler catalysis in which the need
¦¦ for further research has been found to exist has been in -the
provision of catalyst compositions suitable for ~se in a
¦! commercially-feasible process for preparing ethylene polymers
¦having a narrow molecular weight distribution and a good
balance of physical properties. Such polymers have
jlparticular application in the production of articles that are
! formed by injection molding; typically have molecular weight
distributions such that their normalized V30/V300 melt
viscosity ratios are in the range of about 1.5 to 2.3, with
the ratios in the lower portion of this range being generally
preferred but difficult to attain with known processes that
¦might otherwise be commercially feasible; and - like other
jlpolymers intended for commercial use - are desirably prepared
iby a process which is as economical as possible as well as
being capable of producing a polymer having the desired
llproperties.
., . I
3~3~36
There are, of course, known processes ~or preparing
ln~CCtiOn molding resins by polymerizing ethylene with tlle
aid of Ziegler catalysts. However, the known processes
typically suffer one or more of the disadvantages of lack of
economy, inability to produce polymers having a suitable
l balance of properties, and/or unreliability in producing such
li polymers - particularly in commercial-scale operations.
ll U.S. Patent No. 4,003,712 by Miller teaches a
¦I gas-phase fluidized bed system and process which are capable
of being scaled up to commercial size and, being a~
' solvent-free, would be less expensive than processes which
jl use solvents or liquid diluents. However, Miller's silyl
i chromate catalyst does not give polyrners oE the clesired
I! rnolecular we:ight distribution and good balarlcc o~ physical
¦¦ properties. ~Iis system contairls some Eeat~lres which tend to
¦ shorten commercial "on-stream" time. He does not teach how
l! to avoid polymer buildup on reactor surfaces; a phenomenon
¦¦ variously referred to as "coating", "fouling", or "sheeting".
What is still needed is a process employing a
¦i catalyst which (a) is suitable for use in a gas-phase
polymerization process, (b) is capable of yieldlng polymers
¦ having a narrow molecular weight distribution and a good
¦ balance of physical properties, (c) has sufficient activity
to be economically attractive, (d) does not cause reactor
il wall fouling,~and (e) a gas-phase fluidized bed process which
~l allows the catalyst to perform at its full potential at
commercial scale.
British Patent No 1,489,410 (Monsanto~ teaches
!i gas-phase polymerization processes which, because of their
use of supported Ziegler catalysts havlng a vanadium
component and other factors, are commercially attractive
processes. However, as taught in the patent, the processes
¦ are designed to result in the formation of polymers having
,j the broad molecular weight distributions suitable for blow
'I molding resins rather thal. the narrower molecular weight
,
~ 4-
94~3~>
/P 11
distributions needed for injection molding resins: and the
patent itself does not suggest how its processes might be
modified to result in the formation of polymers having
narrower molecular weight distributions. Attempts to make
the processes of the Monsanto patent suitable for the
preparation of injection molding resins by combining its
teachings with the teachings of publications that discuss
means of narrowing molecular weight distribution have not
been successful. For example, polymers having a sufficiently
narrow molecular weight distribution have not been obtained
when Monsanto's preferred vanadium halides have been replaced
with the alkoxy group-containing vanadium compounds which are
within the scope of their patent and which U.S. Patent Nos.
3,457,244 ~E`ukuda et al.) and 3,655,583 (Yamamoto et al.)
teach to result in the production of polymers havirlcJ narrow~r
molecular weight distributions when unsupported cataLy~t
systems are employed.
~ .S. Patent No. 2,965,626 hy Pilar et al discloses
polymerizing organic compounds containing ethylenic
unsatuation under relatively mild polymerization conditions
with catalysts and alcohol catalyst promoters. More
specifically Pilar et al found that the polymerization
activity of the catalyst prepared by reaction of alkali
reagents with the specified metal salts can be ~ubstantially
increased by the inclusion of an alcohol in the reaction
zone. U.S. Patent No. 3,163,611 by Andersen et al pertains
to the production of high density polyethylene by
polymerizing ethylene in the presence of a catalyst
exempli~ied by the material obtained by the interaction of a
trialkylaluminum with titanium tetrachloride.
U.S. Patent No. 3,202,645 to Yanc~y presents a
process for polymerizing and copolymerizing alpha mono and
dl-oleflns by catalysts comprising ~a) the product of the
!l ~
I,j I
~, j 1,
~ 3~3~
I reaction bet~een a compound of a metal choscn from the gr~up
I consisting of the metals of Group IIb and IIIb (where the
qroup numbers correspond to the Mendeleev Periodic Table) and
hydroxyl groups on the surface of a finely-divided
j particulate inorganic solid, preferably finely-divided silica
or alumina, and ~b) a halide-type compound of a Group IVa, V,
¦¦ VIa, VIIa, or p riod 4 of Group VIII metal. The
li polymerization ~f copolymerization reaction can be effected
¦¦ at suitable te~peratures within the range of from about - 25
¦I C. to about 250 C., and pressures ranging from below
'¦ a-tmospheric upwardly to any desired maximum pressure, for
example, 3~,000 p.s.i.g. or even higher pressures. U.S.
j Patent No. 3,718,636 to Stevens et al teaches obtaining
Il polyolefins having a wide distribution of molecular weights
¦¦ through~the use of a catalyst eomprising an organom~tallic
compound, and a solid complex component obtained by reactin~
a solid bivalent met~l compound with an impregnation agent
which consists of an organometallic compound, separating the
solid reaction product, and reaeting the solid reaction
product with a halogenated derivative of a transition metal.
Stevens et al teaehes in U.S. Patent No. 3,787,384 another
l catalyst suitable for use in olefin polymerization and olefin
¦ copolymerization which comprises
(a) at least one organometallic compound, and
jl (b) a solid eatalytic component obtained by
reacting a sUpport composed of silica, alumina or both silica
and alumina wlth a compound of the formula MRnXm n in which M
i is aluminum or magnesium, R is a hydrocarbon radical
¦¦ containing 1 to 20 carbon atomst X is hydrogen or a halogen,
¦I m is the valence of M, and n is a whole number not less than
¦~ 1 nor greater than m, separating the solid product of the
reaction, reacting said product with an excess of a
halogen-containiny transition metal compound, and separating
, the solid reaction product.
j U.S. Patent No. 3,925,338 to Ort teaches that
l control of particle size of olefin polymers produced by
i -6-
/ ~ 3~
gas-phase polymerization of at least one ~lefin ~sing
Ziegler-type catalysts deposited on solid supports in a
fluidized-solids operation is effected by controlling the
particle size of the catalyst support. U.S. Patent No.
4,232,140 also to Ort discloses the use of
trichlorofluoromethane as a promoter il- the polymerization
and copolymerization of ethylene with supported Ziegler-type
vanadium compound/alkylaluminum compound catalysbs in the
presence of hydrogen. Ort finds that polymer yields with his
supp~rted vanadium-based catalysts are -too low for commercial
viability unless the catalyst is promo-ted to high yield with
the trichlorofluoromethane promoter. The viscosity ratio
data in Ort's examples, which may be rela-ted to molecular
weight distribution, indica-te that none of the polymers have
narrow molecular weight distribution. Ort does not teach or
suggest how to avoid reactor fouling.
Fukuda et al. also teach t~_~ethylene copolymers or
terpolymers having narrow molecular weight distribution~ can
be obtained by the use of an unsupported catalyst composition
prepared by ~l~ mixing an alcohol containing l to 12 carbon
atoms with VOC13 and then (2) mixing the mixture thus
obtained with an alkylalwninum compQund in the presence of
the monomers to be interpolymerized, and there are other
patents, e.g., Stamicarbon's British Pat. No. 1,175,593 and
U.S. Pat. Nos 3,535,269 (Tanaka e-t al.) 4,071,674 (Kashiwa et
al.) and 4,~56,865 (Hyde et al.) which teach the use of
catalyst compositions prepared by adding an alcohol at some
stage during the catalyst preparation. However, although
some of these patents are concerned with the production o~
polymers having narrow molecular weight distributions, none
of them teaches a catalyst composition which ~ ~e~ the
aforementioned need for a catalyst suitable for use in a
commercially-attractive gas-phase polymerization process that
is capable of producing injeCtion molding-grade polymers
having a good alance cf physical prcperties.
7-
i3'~3~3~i
n object of the invention is to provide an
il economical commercial polymerization process for preparinc3
¦l ethylene polymers having narrow-to-intermediate molecular
¦l weight distributioll and a good balance of physical
~¦ properties.
¦ Another object is to provide non-fouling catalyst
j compositions which are useful in an economical gas-phase
¦ process for polymerizing one or more monomers comprising
. ethylene to polymers having a narrow-to-intermediate
: ~ molecular weight distribution and a good balance of physical
I properties.
¦ The foregoing objects of this invention are broadly
¦ accomplished by providing a process of polymerizing a monomer
¦ charge in~luding cthylene comprising the steps oE:
(a) drying an inorganic oxide having surface
: hydroxyl groups to form a support that is
substantially free of adsorbed water;
::: `\
~ ~b) reacting the surface hydroxyl groups of the
:~: ; support with at least a substantially
stoichiometric amount of at least one
organometallic compound corresponding to the
: I formula RXMR'yR"z, wherein M is a metal of Group
III of the periodic table, R lS alkyl yroup
containing 1 to 12 carbon atoms, R' and R" are
independently selected from the group consisting of
:~ jj H, Cl, and alkyl and alkoxy groups containing 1 to
; :il I2 carbon atoms, x has a value of 1 to 3, and y and
z both represent values of O to 2, the sum of which .
l is not greater than 3-x;
,: 11 ':
(c) reacting the thus-treated support with at
l~ least about 0.001 mol, per mol of
,j organometallic compound, of at least one vanadium
I'
' I -8-
~ij39'16 1 1~
/ I compound corresporlding to a formula sel~cted Erom .
! (RO) VOX3 and (RO)mVX4 m~ in which formulas R .
¦ rcyrescl~ts ~ Cl-C18 monovalent hydrocarbon radical
j that is free of aliphatic unsaturation, X is Cl or
Br, n has a value of 0 to 3, and m has a value of 0
to 4; .
Il
(d) reacting the product of step (c) with at least
¦ about 0.1 mol, per mol of organometallic compound, ::i
of an alcohol containing 1 to 18 carbon atoms;
ll
(e) feeding the product of step ld) into a
Il gas-phase reaction zone;
I! (~) Eeedillq, separc~t~ly and independerltly o said
feedincJ step (e), a tr:ialkyl~luminum into the
¦ gas-phase reaction zone in order to form a bed in
¦ the gas-phase reaction zone which comprlses the
product of step (d) and the trialkylaluminum;
(g) fluidizing the bed of step (f) at a pressure
¦ of between about 0.7 and 4.2 MPa and a temperature
of between about 50 to 120 C. by difEusin~
underneath the bed of step (f) a gas mixture
¦ comprising ethylene, hydro~en, and chloroform at a
¦ rate sufficient enough to give a linear ~as
jj velocity in the bed of step (f) of between about 15
I to 60 cm/sec;
¦l (h) removing particulate polymerized substantially
Ill et ~ylene particles from the reactlon zone~ aDd
il (i) recycling unreacted gas mixture of step (g)
from the top of the reaction zone to the bottom of
i,¦ the reaction zone.
Il .
i2~3~'3~3~i
This invention is a novel process oE polymerizing a
monomer charge having ethylene. An inorganic oxide with
surface hydroxyl groups is dried to form a support that is
substantially free of adsorbed water. The surface hydroxyl
groups of the support are reacted with at least a
substantially stoichiometric amount of at least one
organometallic compound corresponding to the formula
RXMR'yR'' , wherein M is a metal of Group III of the periodic
table, R is an alkyl group containing 1 to 12 carbon atoms,
R' and ~" are independently selected from the group
consisting of H, Cl, and alkyl and alkoxy groups containing 1
to 12 carbon atoms, x has a value of 1 to 3, and y and z both
represent values of 0 to 2, the sum of which is not greater
than 3-x. The thus-treated support is reacted with at least
about 0.001 mol, pcr mol oE organometallic compourld, of at
least one vanadium compound corresponding to a Eormula
selected from (RO)nVOX3 and (RO)mVX4 m~ in which formulas R
represents a Cl-C18 monovalent hydrocarbon radical that is
r~e of aliphatic unsaturation, X is Cl or Br, n has a value
of 0 to 3, and m has a value oE 0 to 4. This product is
reacted with at least about 0.1 mol, per mol of
organometallic compound, of an alcohol containing 1 to 18
carbon atoms, in order to form a catalyst product. The
catalyst product is fed into a gas-phase reaction zone.
Separately and independently of thic feeding, a
trialkylaluminum is fed into the gas-phase reaction zone in
order to forrn a bed in the gas-phase reaction zone which
includes inter alia the catalyst product and the
trialkylaluminum. The bed is fluidized at a pressure of
between about 0.7 and 4.2 MPa and a temperature of between
about 50 to 120 C by diffusing underneath the bed including
the catalyst product and trialkylaluminum a gas mixturc
comprising ethylene, hydrogen, and chloroform a~ a r~-itc
5ufficient enough to give a lil~ear gas velocity in ~*~
comprising catalyst product and trialkylaluminum of betwcen
~,
il -10- 1
~ i399~; i
about 15 to 60 cm/sec. Particulate polymerized substantially
ethylen~ particles arc relTloved from the reaction zone, and
unreacted gas mixture of ethylene, hydrogen and chloroform is
recycled from the top of the reaction zone to the bottom of
the reaction zone.
The inorganic oxide used in preparing catalyst
composition of the inven-tion may be any particulate inor~anic
oxide or mixed oxide, e.g., silica, alumina, silica-alumina,
magnesia, ~irconia, thoria, titania, etc., having surface
hydroxyl groups capable of reacting with the organometallic
compound. However, it is generally an inorganic oxide
selected from the group consisting of silica, alumina,
magnesia and mixtures thereof, i.e., physical mixtures, such
as mlxt~res of silica and alumina particles, ctc., and/or
chemical mixtures, ~ucll as magnesum silicate, aluminum
silicate, etc. 'rhe surface hydroxy~ groups may be at the
ou-ter surface of the oxide particles or at the surfaces of
pores in the particles, the only requirement in this regard
being that they be available for reaction with the
organometallic compound.
The specific particle size, surface area, pore
volume, and number of surface hydroxyl groups characteristic
of the inorganic oxide are not critical to its utility in the
practice of the ïnvention. However, since such
characteristics determine the amount of inorganic oxide that
it is desirable to employ in preparing the catalyst
compositions, as well as sometimes affecting the properties
of polymers formed with the aid of the catalyst compositions,
these characteristics must Erequently be taken into
consideration in choosing an lnoryanic oxide for use in a
par-ticular aspect of the invention. For exampler when the
catalyst composition is to be used in a gas-phase
polymerization process - a type of process in wh:ich it is
known that the polymer particle size can be varied by varying
1~3'3~36 l
the particle size of the support - the inorganic oxide used
in preparing the catalyst cornposition should be one having a
particle size that is suitable for the production of a
polymer having the desired particle size. In general,
optimum results are usually obtained by the use~of inorganic
oxides having an average particle size in the range of about
30 to 600 microns, preferably about 30 to lOG ~icrons; a
surface area of about 50 to 1000 square meters per gram, ¦
preferably about 100 to 400 square meters per gram; and a
pore volume of about 0.5 to 3.5 cc per gram, preferably about
0.5 to 2 cc per gram.
As indicated above, the organometallic compound
that is reacted with the surface hydroxyl groups of the
inorganic oxide in the practice of the invention may be any
one or more organometallic compounds corresponding to the
formula RXMR'yR"z, wherein M is ~ metal o~ Group III of the
pel-iodic tabl~, R is an alkyl group containing 1 to 12 carbon
atoms, R' and R" are independently selec~ed from the group
consisting of H, Cl, and alkyl and alkoxy groups containing 1
to 12 carbon atoms, x has a value of 1 to 3, and y and z both
represent values of 0 to 2, the sum of which is not greater
than 3-x. Thus, M may be, e~g. aluminum, gallium, indium, or
thallium; R may be, e.g., methyl, ethyl, propyl, isopropyl,
n-butyl, n-pentyl, isopentyl, t-pentyl, hexyl,
2-methylpentyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl,
dodecyl, etc; R', when present, may be H, Cl, an alkyl group,
such as one of those exemplified above for R, which is the
same as or different from R, or an alkoxy group, such as the
alkoxy groups corresponding to the aformentioned alkyl
groups; and R", when present, may be any of the substituents
mentioned above as exemplary of R' and may be the same as or
different from R'.
The preferred organometallic compounds are those in
which M is aluminum. Utilizable aluminum compounds include
chlorides, such as dimethylaluminum chloride, diethylaluminum
12-
2~j3~3~i
chloride, dipropylal~mi~um chloride, diisobutylalumir-um
chloride, the corresponding alkylalurninum dichlorides, etc.,
and mixtures of such chlorides, but the chloridcs are
generally not particularly preferred because of the halogen
residue they contribute to polymers made in -their presence.
The more preferred aluminum co~pounds are the
trialkylaluminums, dialkylaluminum hydrides, dialkylalumlnum
alkoxides, and alkylaluminum dialkoxides, such as
trimethylaluminum, triethylaluminum, tripropylaluminum,
tributylaluminum, triisobutylaluminum, isoprenylaluminum,
trihexylaluminum, trioctylaluminum, tridecylaluminum,
trldodecylaluminum, etc.; the correspondinq alkoxy compounds
wherein one or two of the alkyl groups have been replaced by
alkoxy groups, such as ethylalumlnum diethoxide,
dicthylalumirl~lm ethoxide, ethylalum.inum scs~uLethoxide,
ethylaluminum diisopropoxide, etc.; diethylalumin-lm hydride,
di-n-propylaluminum hydride, diisobutylaluminum hydride,
etc.; and mixtures of such compounds.
Especially preferred aluminum compounds are the
trialkylaluminums, particularly triethylaluminum and
¦tri-n-hexylaluminum, which are advantageous to employ because
of their cost, availability, and/or efEectiveness. When a
trialkylaluminum is used as the organometallic compound, it
is generally found that - all other factors being constant -
the molecular weight distribution of polymers prepared with
the catalysts of the invention are narrowed as the chain
lengths of the alkyl groups of the trialkylaluminum are
lengthened.
The amount of organometallic compound employed is
¦¦at least substantially the stoichiometric amount, i.e., the
¦¦amount required to react with all of the available hydroxyl
groups on the inorgarlic oxide. Use of an amount'less than
the substantially stoichiometric amount would broaden the
molecular weight distributions of polymers formed in -the
l¦presence of the catalyst compositions; use of an amount
!1,
1~ -13-
3t36
;i
greater th~n the substantlally stoichiometic amount is
permissable within the scope of the invention but frequently
serves no practical purpose and can be disadvantageous in
that the excess organometallic compound sometimes leads to
fouling of the polymerization reactox if not removed from the
catalyst composition prior to the composition's being used. ¦
When the number of available hydroxyl groups on the
particular inorganic oxide being treated is not known, it can
be determined by any conventional technique, e.g., by
reacting an aliquot of the inorganic oxide with excess
triethylaluminum and determining the amount of evolved
ethane. Once the number of available hydroxyl groups on the
inor~anic oxide is known, the amount of or~anometallic
compound to be ernployed is chosen ~o a3 to prov:ide at lcast
about one mol oE orcJanometall.ic compound per mol o~ availabLe
hydroxyl groups.
The vanadium component of the catalyst compositions
of the invention may be any one or more compounds
corresponding to a formula selected from (RO)nVOX3 ~ and
(RO)mVX4 m~ wherein R represents a monovalent hydrocarbon
radical that contains 1 to 18 carbon atoms and is free of
aliphatic unsaturation, X is C1 or Br, n has a value o 0 to
3, and m has a value of 0 to 4. Thus, the utilizable
vanadium compounds include VOC13, VOBr3, and the indicated
mono-, di-, and trihydrocarbyloxy derivatives thereof, as
well as VC14, VBr4, and the indicated mono-, di-,. tri-, and
tetrahydrocarbyloxy derivatives thereof; and R, when present,
may be a straight- or branched-chain alkyl, cycloalkyl, aryl,
alkaryl, or aralkyl group, such as methyl, ethyl, propyl,
isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl,
heptyl, octyl, cyclooctyl, nonyl, decyl, dodecyl, hexadecyl,
octadecyl, phenyl, benzyl, dimethylphenyl, ethylphenyl, etc.
When mixtures of vanadium compounds are employed, the
vanadium component may be a mixture of two or more compounds
!l
- 1! -14-
3~36 1~
~ I ~
I correspondir)g to either of the g~neral formulas given abovc
I or a mixture of one or more compounds corresponding to one of
I those ~cneral formulas with one or more compounds
~j corresponding to the o~her of thosè general formulas.
Ordinarily, when a vanadiun~ compound of the
il (RO)nVOX3 n type is employed, it is preferably a compound
¦l wherein X is Cl, becauseAthe greater avai:Lability of such
compounds; and it is preferably a monoalkoxy compound, since
all other factors being constant, the use of VOC13 or
il VOBr3 in the preparation of the catalyst compositions of the
il invention does not permit the attainment of-~-narrow a
molecular weight distribution as can be obtained when the
¦¦ polymerization reactions of the invention are conducted ln
i the presence of the catalyst compositions that are prepared
by the use of the hydrocarbyloxy derivatives of VOC13 or
! VOBr3 and ~2) the use of hydrocarbyloxy derivatives other
than the monocllkoxy compounds docs not appear to oEfe~r
advantages that would compensate for the greater difficulty
and cost of obtaining them. Thus, considering both cost and
effectiveness in the practice of the invention, the preferred
(RO)nVOX3_n compounds are those compounds in which R is
¦alkyl, X is C1, and n has a value of abou-t 1.
Ordinarily, when a vanadium compound of the
!! ~RO)mVX4 m type is employed, it is preferably VC14 or a
derivative thereof, most preferably VC14 itself. The use of
! VC14 in the preparation of catalyst composltions of the
¦invention leads to the Eormation of compositions which are so
¦satisfactory in the production of injection molding-grade
¦¦ethylene polymers that there is seldom any reason to use a
¦¦more expensive (RO)mVX4 m compound instead of it.
l~ The amount of vanadium compound(s) employed in the
¦¦practice of the invention may be varied considerably but is
generally such as to provide at least about 0.001 mol of
l;vanadium compound per mol of organometallic compound. When
¦¦the catalyst composition is to be prepared by the preferred
11
.". . . j~ -15-
1~3~3636 ll
proc~ss described below, wherein no washing step is utilized 1,
during or after preparation of the compositions, the amount
of vanadium compound employed should not be substantially in ,j
excess of the amount capable of reacting with the treated
support, i.e., about 1 mol of vanadium compound per mol of
organometallic compound. Use of a greater amount would serve
no practical purpose and could be disadvantageous in that the
excess vanadium compound could lead to fouling of the
polymerization reactor. However, a larger amount of vanadium
compound may be employed when fouling of the reac~or is not
expected to be a problem and/or excess vanadium compound will
be removed from the catalyst composition before the
composition is used. In the practice of the invention, the
amount of vanadium compound employed is generally not in
exce55 o about 3 mols per mol of organomet~,lLic co~pound,
and excellent results are ob~ained by the use o about 0.03
to 0.2 mol of vanadium compound per mol of organometallic
compound, i.e. about 5 to 30 mols of organometallic compound
per mol of vanadium compound.
As indicated above, the alcohol empl~yed in
preparing the present catalyst co~lpositioTl~ may ~ any
alcohol containing 1 to 18 carbon atoms; and it may be
conveniently defined as a compound corresponding to the
formula ROH, wherein R may be any of the groups, or types oE
groups, mentioned above as exemplary of the R groups of the
utilizable hydrocarbyloxy compounds.
When the vanadium compound, or one of the vanadium
compounds, emyloyed in the practice of tlle invention is a
hydrocarbyloxyvanadium compound that the catalyst
manufacturer will synthesize for that use, i~ is frequently
desirable, as a matter of convenience, to`employ an alcohol
com~onent indenticaI to the alcohol required to synthesize
the desired hydrocarbyloxyvanadium compound. However, it is
not necessary for the R group of the alcohol to correspond to
the R group of any hydrocarbyloxyvanad1um compound being used
ll
1l -16-
j3'3''3~i ~:
~ I to prep~e th~ catalyst composition; and, in fact, , r
/ ¦ correspondence of the R groups could be undesirable in some
~¦ ins-tances.
I For example, if a practitioner of the invention
~! warlted to use ethoxyvanadium oxydichloride as his vanadium
,! cornpound but also wanted to prepare a catalyst composition
il that would provide the narrowest possible molecular weight ;
distribution in polymers formed in its presence, it would be
l more desirable for him to use a long chain alcohol, rather
i than ethanol, as the alcohol, because all other factors being
¦ constant, the molecular weight distribution is narrowed as ,
the chain length of the alcohol is increased. Increasing the
chain length of the hydrocarbyloxy group tends to narrow the
molecular weight distribution.
The preferred alcohols are primary alcohols, with
~n-alkanols containing 6 to 18 carbon atoms b~ing partlcularly
preferred.
The amount of alcohol used in preparing the
¦catalyst composition of the invention should be at least ~l
¦about 0.1 mol per mol of organometallic compound employed.
IThere is no maximum amount of alcohol that may be utilized,
jbut its beneficlal effects begin decreasing when an optimum
amount is exceeded, so it is generally not used in excess of
10 mols per mol of organometallic compound. Ordinarily, the
~amount of alcohol u-tilized in the practice oE the invention
is in the range of about 0.2 to 3, preferably about 0.3 to 1,
~!most preferably about 0.35 to 0.7, mols per mol of
¦¦organometallic compound.
As indicated above, the catalyst compositlons of
the invention are prepared by drying the inorganic oxide,
reacting the dried inorganic oxide with the organometallic
compound, and reacting the thus-treated support with the
! vanadium co~pound, and then reacting that reaction product
~! with the alcohol. The conditions under which -the inorganic
oxide is dried are not critical as long as they are adequate
Il
ll
., i`l
~ 17-
i3'3'36
to provide an inorganic oxide that has surface hydroxyl
groups alld is substantlally free of adsorbed water. ~lowever,
it is ordinarily preferred to dry the inorganic oxide at
about 100 to 1000 C., with or without a nitrogen or other
inert gas purge, until substantially all adsorbed water is
removed. Also, although improved results are obtained by the
use of the catalyst compositions of the invention, regardless
of the particular temperature at which the inorganic oxide is
dried, the drying temperature has been found -to have a
negligible-to-noticeable effect on those results - optimum
results generally being obtained when the inorganic oxide has
been dried at about 200-600 C., but drying tempera-tures of
about 500-600 C. generally being required for optimum
results when the inorg~nic oxide is alumina. The time
required for drying oE t!le inorganic oxide varies, oE course,
with the particular ~ryiny temperature used but is usually in
the range of about 5-16 hours.
When the inorganic oxide has been substantially
freed of adsorbed water, its surface hydroxyl groups may be
reacted with the organometallic compound in any suitable
manner, conveniently by (1) adjusting its temperature, if
necessary, to the temperature at which the reaction with the
organometallic compound is to be conducted, (2) slurrying it
in an inert liquid hydrocarbon, generally a C4-C8
hydrocarbon, such as isobutane, pentane, lsopen~ane, hexane,
cyclohexane, heptane, isooctane, etc., and mixtures thereof
with one another and/or with other materials commonly present
in commercial distillation cuts having the desired boiling
range, (3) adding a substantlally stoichiometric amount of
the organometallic compound in neat or solution form, and ~4)
maintaining the organometallic compound in intimate contact
¦with the inorganic oxide, e.g., by agitating the slurry, for
a time sufficient to ensure substantially complete reaction
with the a~ai].able hydroxyl group:, gen:r:lly at least about
-18-
39'~6
71285-8
5 minutes. The reaction may be conducted with or without pres-
sure and at ambient or reflux temperatures, depending on the
particular organometallic compound employed, as will be readily
understood by those skilled in the art. When the or~anometallic
compound is added in solution form; it is generally preferred,
through not required, that the solvent be the same inert li~uid
hydrocarbon as is already present in the slurry.
The reaction of the vanadium component with the treated
support may also be accomplished by conventional means, such as
any of the techniques described in British Patent ~o. 1,489,410.
However, it is st desirably accomplished simply by adding the
vanadium compound in neat or solution form to the slurry of
treated support and maintaining it in intimate contact with the
treated support for a time sufficient to provide for substantial-
ly complete reaction, usually at least about 5 mlnutes and
preferably about 10-60 minutes, although, actually, the reaction
is virtually instantaneous.
When reaction of the vanadium component with the
treated support has been completed, reaction with the alcohol
may be accomplished in any suitable manner, conveniently just
by adding the alcohol to the vanadium component/treated support
reaction product and maintaining it in contact therewith, e.g.,
by agitating the slurry, for a time sufficient to ensure sub-
stantial completion of the desired reaction, usually at least
about 5 minutes and most commonly about 30-60 minutes. All that
is critical about the manner in which the alcohol is reacted with
the other catalyst components is the time at which it is added
to the system. Reaction of the other components with one
another must be substantially complete before the alcohol is
~: 30 added in order Eor the catalyst compositions to have the desired
performance capabilities.
-- 19 --
~'
,. .~,~
39~ 1
/~ I
fter the alcohol has b~en reacted with the othcr
c~talyst compone~ts, the resultant catalyst composition may
or may not require further treatment to make it suitable for
use, depending on the particular process that has been used
to prepare the catalyst composition and the particular type
of polymerization process in which it is to be used. For
example, if the catalyst composition has been prepared by a
type of process which results in its being already dry when
reaction with the alcohol has been accomplished, no further
treatment is likely to be necessary if the composition is to
be used in a gas-phase polymerization process; but slurrying
of the composition in a suitable liquid medium may be
desirable if it is to be used in a slurry or solution
polymerization process. On the other hand, if the catalyst
composition has been prepared by the preferred process
described ~bove, i.e., if the inorgar-ic oxide has been
slurried in a liquid medium prior to the addition of the
other components, it is already suitable for use in a slurry
or solution polymerization process but will have to be dried
to make it suitable for use in a gas-phase polymerization
process. When the composition is to be dried, i.e., freed of
any liquid medium used in its preparation, the drying may be
achieved by any conventional technique, e.g., filtration,
certrifugation, evaporation, blo~ing with nitrogen, etc.
Commerical preparation of the catalyst of this invention is
preferably carried out as taught by Rogers in U.S. Patent No.
4,426,317.
Regardless of the particular techni~ue used to
prepare the catalyst compositions of the invention, it should
be kept in mind that~they are Ziegler catalysts and are
therefore susceptible to poisoning by the materials, such as
oxygen, water, etc., that are known -to reduce or des-troy the
effectiveness of Ziegler catalysts. A~cordingly, they should
be prepared, stored, and used under conditions that will
!
,, ij ~o
~,3~3~36
71285-8
permit them to be useful as polymerization catalysts, e.g., by
the use of an inert gas atmosphere, such as nitrogen.
~ he invention is particularly advantageous in that it
provides catalyst compositions which (1) have the active in-
gredients chemically-attached to an inorganic oxide support, (2)
are capable of producing ethylene polymers having a narrow-to-
intermediate molecular weight distribution, as desired, and a
good balance of physical properties by an economical gas-phase
process that gives a high yield of polymer and ~3) do not foul
1~ gas-phase reactors. The fact that high yields of polymer can be
obtained by the use of the catalyst compositions is particu:Larly
unexpected in that these high yields are attalnable even when
the catalyst compositions a.re prepared b~ th~ preferrecl p.rocess
whe.rein no washing step is required or utilized during or after
preparation of the compositions. Both experience in the field
and the teachings of the prior art indicate that at least one
washing step should be required in the preparation of such com-
positions when high yield catalysts are desired.
After the catalyst composition of this invention is
prepared, it is subseqNently introduced into a gas-phase fluid-
ized reactor similar to that taught by Miller in United States
Patent No. 4,003,712. In a preferred embodiment of the invention,
the diameter of the velocity reduction or disengaging zone at the
top of Miller's reactor is enlarged and the cyclone and filter
in the gas recycle system are eliminated for stable, long-term
commercial operation. It should be understood that polymeriza-
tion with the catalyst compositions o this invention may be
conducted in any fluidized system which has a distribu~ion plate
means and allows a monomer gas to fluidize a bed including the
catalyst compositions; allows unreacted monomer gas to be re-
recycled fr.om the top of the fluidized system back to the bottom
of the fluidized system
:! 21
3~3~
/ li or for admixing with thc monomcr gas prior to its diffusing
/ or passing thro~yh the fluid.ized bed; allows a polymer
/ !I product to be withdrawn from the fluidized bed; allows
i catalyst and a trial~ylaluminum to be added to the fluidized
bed; and provides for the removal of the heat of
polymerization. Size, shape, pressure rating, heat removal
i¦ capability, and other factors can limit the polymer
production capacity of the gas-phase fluidized-bed reaction
Il systems of this invention. The process of this invention may
¦I be practiced in commercial facilities having production
¦ capacities of 50,0~0 to 250,000 metric tons per year or more.
The process of this invention may also be practiced in
laboratory scale reactors having a production capacity of
from about 0.1 to 1.0 kg/hr or in pilot p:Lant reactors having
¦ p.rocluctlon capac.i~i~s oE Erom S to 5Q0 Ic~/hr.
¦ ~'h~ c~talyst compositions oE ttliS lnvelltLon should
preferably be injected or Eed to the fluidized bed system at
a point between the distribution plate and about 7/8 o~ the
height of the catalyst bed from the distribution plate of the
! reactor. More preferably, the catalyst compositions are fed
il into the fluidized bed system at a point of between about 1/8
¦ to about 1/2 of. the heigh-t of the fluidized bed. Injection
! of the catalyst composition above about 1/8 of the height of
the bed (as opposed to below 1/8 of the height) offers
distribution of the catalyst composition throughout the
¦ entire ongoing fluidized bed to retard and/or preclude the
1~ formation of localized spots of high catalyst composition
¦¦ concentration which would result in the formation of "hot
¦¦ spots" at or near thc distri.bution plate~ A "hot spot" is a
¦¦ localized region ln which the~exothermic heat of .
polymerization is not dissipated before some polymer h~ to
¦¦ the softening point of the polymer. Any introduction of -the
~ 4~1yS~
`! ~ t~ t~ compositions o-f this invention at a point above
i about 7/8 of the height of the fluidized bed frotn the
distribution plate of -the reactor rnay lead to excessive
¦ carryover of the fresh catalyst of this invention into the
-- 11
~ ,2-
39~36
gas recycle system. The rate of injection or rate of feed of
the catalyst composition of this invention is any suitable
rate which is equal to catalyst consumption in the
polymerization process of this invention and generally
depends on the size of the fluidized bed system. The rate of
production of the particulate polymerized substantially
ethylene particles in the fluidized bed is partly determined
by the rate of catalyst injection. We have found that the
rate of injection of the catalyst for our polymerization i~
process is generally preferably at a rate that maintains the
concentration of the vanadium in the fluidized bed between
about 1/10 ppm to about 50 ppm based on weight of vanadium
metal divided by total solids in the bed. More preferably,
the rate of injec:tion oE the catalyst is that which would
maintaln the concentrakion Oe the vanadium .in thc ~luldlæed
bed between about 0.50 ppm to about 10 ppm; most preferably,
between about 1 ppm to about 4 ppm. The fluidized bed is
substantially particulate polymerized ethylene polymer
particles formed by polymerization of the monomer~s) on the
catalyst compositions of this invention.
In order for the catalyst composition of this
invention to give high yield of polymer product per unit of
vanadium component, we have discovered that it is necessary
to add or inject at least one trialkylaluminum compound into
the fluidized bed system as a co-catalysts. For a variety of
reasons, it is preferred to add the trialkylaluminum
compound, or the mixture of trialkylaluminum compounds, that
i5 being used as a co-catalyst directly to the fluidized bed
il
separately and independently of the catalyst and at an
injection point removed from the catalyst injection point.
However, the process of this invention does not depend on the
method of feeding the trialkylaluminum co-catalyst or the
location of its injection point. The trialkylaluminum
compounds of this invention may be fed to the f luidized bed
as pur~ compounds, or in solution in a liquid hydrocarbon
which will vaporize in the fluidized bed. Suitable
~ ~i399~:i ~
hydrocarbon solvents include, but are not limited to,
isobutane, isopentane, hexane, heptane and mixtures ~hereof.
The trialkylaluminum oE ~his in~ention snay be any
trialkylaluminum wherein the alkyl or combination of alkyl
groups contain between 1 and about 36 carbon atoms. In a
preferred embodiment of the invention, the alkyl group or
combination of alkyl groups contain between 1 and about 12
carbon atoms. Suitable trialkylaluminum compounds have been
found to lnclude trimethyl-, triethyl,- tri-i-butyl-,
tri-n-hexyl-, tri-n-octyl- and ethyl di-i-butylaluminum. It
should be understood that trialkylaluminum compounds add
ethylene, and alpha olefins to some extent, under the
operating temperatures ~lld pressures o~ the polymerization
process of ttle invention. rrhus, an ethyl group on alum.irluln
may he inserted by ethylelle to become~ a butyl group, etc.
Therefore, there is no reason to believe or require that all
alkyl groups on the aluminum be -the same. There is every
reason to believe that mixtures of trialkylaluminum compounds
are generated during polymerization and are as effective as
pure compounds. Since the exact composition of the alkyl
groups on aluminum during the polymerization process of this
invention is not known because of the ethylene insertion
reaction, all of the -trialkylaluminum species in the
fluidized bed are referred to collectively Eor the purposes
herein as "trialkylaluminum".
As was the case for the catalyst composition of
this invention, the rate of injection of the
trialkylaluminum is also any suitable rate which is equal to
the trialkylaluminum consumption in the polymerization
process, and also depends on the size of the fluidized bed
system. Polymer productivity from the polymerization process
is not only determined by the rate of catalyst injection, but
also from the rate of trialkylaluminum injection.
-24-
~ ;39~36
Assuming that the trialkylaluminum compounds of
this inventionremain in the fluidized bed and assuming
uniform distribution of trialkylaluminum throughout the
fluidized bed, the molar concentration of trialkylaluminum
may be calculated from the molar feed rate of the
trialkylaluminum being fed into the fluidized bed reaction
system and the withdrawal rate of the polymer product
particles. Likewise, assuming uniform distribution of the
catalyst composition throughout the fluidized bed, the molar
concentration of the vanadium component of the catalyst
composition may be calculated from the molar feed rate of the
vanadium component of the catalyst composition being fed into
the fluidi~ed bed reaction system and the withdrawal rate of
the polymer product particles. At stable, lined-out
operating conditions, the ratio of the molar concentratlon of
the trialkylaluminum to the molar concentration o~ the
vanadium compon~nt in the hed of catalyst composition will
asymptote to the ratio of the molar feed rate of the
trialkylaluminum to the molar feed rate of the vanadium
components oE the catalyst composition of this invention.
For -the catalyst composition of this invention, the injection
rate of the trialkylaluminum should be such that the Al/V
ratio in the ~luidized bed of the molar concentration of the
trialkylaluminum to the molar concentration of the vanadium
component is between about 1 to about 5,000. We have ~ound
that the activity of the catalyst composition of the
invention is maximized in a certain range of trialkylaluminum
to vanadium molar ratio. Too little or too much
trialkylaluminum suppresses the activity of the catalyst
composition and the polymer production. It has been
determined that a plot of the trialkylaluminum to vanadium
molar ratio versus the catalyst (of this invention) activity
possesses a generally flat peak and the optimum
trialkylaluminum to vanadium molar ratio lies in the range of
from about 2 to about 500, with from about 2 to 60 being the
most preEerred from the standpoint of m~nimizinq c-talyst
25-
/ ~ 3~36
/ residue levels in the polymer and trialkylaluminum cost.
/ Therefore, the preferred injection rate of the
/ trialkylaluminum into the fluidized bed system of this
/ invention is that injection rate whercin the molar ratio in
/ ¦ the fluidized bed of the molar concentration of the
~I trialkylaluminum to the molar concentration of the vanadium
il composition is between about 2 to 500, and most preferably
¦¦ from about 2 to about 60.
¦ The bed of particulate polymerized substantlally
I¦ ethylene particles, trialkylaluminum ancl the catalyst
! composition oE this invention has to be fluidized at a
l pressure of between about 0.7 and 4.2 MPa and a temperature
i of between about 50 to 120 C. Fluidization is conducted by
¦ diffusing underneath the bed (and through the distribution
plate) a gas mixture comprising ethylene, hydrogen and
chloroform at a reltc sufEicicnt enougll to cJive c~ lineclr gas
velocity in the bed oE between about 15 to about 60 cm/sec.
¦ The gas mixture will also include inert gas which is used to
¦ feed the catalyst~ compositions to the fluidized bed. A
majority of the gas mixture is in the form of unreacted gas
mixture that is recycled from the top of the reaction zone to
l the bottom of the fluidized bed of the reaction zone.
¦¦ Although the catalyst compositions and the
¦I tr:ialkylaluminum of this invention polymerize ethylene and
! other olefins over a wide range of temperatures, there is a
~1 practical limitation to the temperatures at which -the
gas-phase fluidized-bed process of this invention is
I commercially viable. For example, above about 120 C,
¦ ethylene polymers soften and tend to agglomerate in a
¦ fluidized bed, leading to formation of lumps, loss oE
jj fluidization, and onset of an inoperable condltion. ~elow
about 50 C, the production rate of commercial reactors
becomes so low that the process is no longer profitable. It
, is generally desirable to operate near the highest
! temperature at which the polymer will not agglomerate in thc
~I bed with a temperature safety factor for small temperature
A~ 26-
~ r~ 3 ~316
u~sets so th~t inoperable conditions are not encountered even
brief1y. Tlle~refore, the preferred temperature range is from
about ~ C, with the range from about ~ C being
most preferred.
The pressure at which the polymerization process of
this invention is conducted is selected on the basis of
desired commercial operation rather than upon some limitation
of the catalyst. The catalysts of this invention will
function at atmospheric, subatmospheric, or superatmospheric
pressures. For economy of operation, one wishes to
polymerize near the highest pressure for which the equipment
is designed in order to maximize the production rate for the
equipment. But, because commercia1 process equipment
generally is rnore expcns.iv~ with the higher pre~ssure, there
is a natura1 tencl~llcy to d~sign commercial equipm~ Eor low
pressures. Thes~ constraints lead to a commercial operating
range of about 0.7 - 4.2 MPa. At the lower pressures,
however, higher dwell or residence times in the reactor are
required to reach high yields of polymer per unit of
¦catalyst. At the higher pressures, there is little room to
safely accommodate pressure upsets. These constraints lead
to a preferred pressure range of about 1.6 - 3.9 MPa.
In order to provide sufficient mixing and agitation
in the bed of trialkylaluminum and catalyst that "hot spots"
will not develop, it is necessary that the flow rate of -the
gas mixture through the bed of polymer particles containing
traces of the catalyst and the trialkylaluminum be sufficient
to fluidize the particles. For the powdered polymer
C~fa ~Ysf'
particles produced by the cataly~ compositions of this
invention, the minimuln fluidization velocity, Gmf, has been
determined to be about 15 cm/sec. As gas velocity increases,
a point is reached at which thè particles are largely swept
out of the bed by the force of the rising gas ~the transport
velocity), which, for the particles of the prese~t invention
jjis about 4 Gmf, or 60 cm/sec. To provide some margin for
',1
!1 -27- l
,~.~,i i . Il .
j;3~6 1~
¦!
o~er~tirlg exror, ttle preferred velocity range is about 1.5 -
3.0 G~lf, or about 23 - 45 cm/sec, in contrast to the 3 - 5
G~nf range pre~erred by Miller in U.S. Patent No. 4,003,712 ~;
for his catalysts.
The cat~lysts of this invention, under the
commercial conditions descri~ed above, in the absenc2 of a
chain transfer agent, produce polymer of a molecular weight
too high for conventional melt processing. Therefore, in the i
commercial practice of this invention the fluidi~ing gas :~¦
mixture must CQntain hydrogen during polymerization to adjust
the molecu ar weight ~as determined ùy melt index~ to the ¦
desired range for the product being produced. This is done
by increasing the hydrogell/ethylene ratio to raise melt index ;
~lower molecular weight), or reducing the ratio to produce
the opposite eEect. The catalyst compositions o~ this
invention are sensltive to hydrogell, so lt is yenerally not
necessary to use more than 10~ by vol. of hydrogen even -to
produce the highest melt index polymer. Furthermore, when
used as described herein, altering the hydrogen/ethylene
ratio to increase melt index does not cause a loss of
production rate in a commercial plant within the range of
melt indexes used for commercial polymers at this time.
Preferably, the amount of hydrogen utilized ln a preerred
embodiment o~ the invention in order to control the molecular
w2ight o the produced polymer is between about 0.10 ~ to
about 10.0 % by volume of the total gas mixture volume.
The gas mixture has to have chloroform in order
that the catalyst compositions of this invention can have
their activity promoted. While o-ther halogenated carbon
f,~ o7~r~lch~oro~e~) a~æ
compounds such as methylene chloride and ~3tr~ G~ Om~hamr
may work as promoters, from the standpoints of promotion of
catalyst activity, cost, availability, ease of handling, and
catalyst promotion without causin~ reactor fouling,
chloroEorm is clearly the compound oE choice. Only small
amounts are needed because of its effectiveness. Uncler the
conditions of polymerization, it is a gas, and generally will
28-
~3~ i
/ ~ be present in the recycle gas at concentrations between about
0.0001 to about 1.000 % by vol of the gas mixture. Since the
¦¦ prefcrred vol ~ ranges for hydrogen and chloroform is
¦¦ r~spectively between about 0.10 and about 10.0 and between
il about 0.0001 and about 1.000, the remaining vol % for any
given volume of the gas mixture would include ethylene and !¦
,¦ any of the inert gas which is used to feed the catalyst
1i compositions to the fluidized bed in the reaction zone. In a
preferred embodiment of the invention, ethylene preferably
comprises between about 50.0 vol % and about 99.9 vol % of
the gas mixture.
t appears that the molar ratio CHC13/V is more
l useful in predicting and understanding its effect than the
I overall concentra~ion in the gas, since it afEects the
catalyst's per~ormance. The CIIC13/V ratio may vary Erom
! about 2 to about 5000. ~ecause chloroform :is relativcLy
nexpensive and used in small amounts, there is no real
¦¦economic incentive to minimize its use. However, there
lappears to be a maximum in the curve of catalyst activity vs.
¦ CHC13/V rati~, with a broad optimum in the range of about 10
- 500. There also appears to be an interac-tion between the
optima for CHC13/V ratio and A1/V ratio such that lower
¦C~C13/V ratios are generally preferred when the A1/V ratio is
Illow, and higher CHC13/V ratios are generally preferred when
¦I the Al/V is high. Other factors, such as impurity levels,
¦jmay also cause a shift in the optimum CHC13/V ratio or A1/V
ratio, but generally such factors will not shift-the optima
outside the preferred ranges.
1l We have found that, in order to control the density
I ¦of the produced ethylene polymer, the gas mixture of
ethylene, hydrogen and chloroform may include alpha olefins
¦which will be copolymerized with the ethylene of the gas
limixture. Although the catalyst compositions of this
¦jinvention will copolymerize essentially any alpha olefin with
¦lj ethylene, there is a practical limit to what can be
li
11 -29-
i39~36
/~1
effectively done in a gas-phase reaction. Generally, olefins
havlrlg more than 8 carbon atorns have too low a vapor pressure
to be used in high enough concentration to have much effect
on density. Propylene, butene-l, hexene-l,
4-methylpentene-1, and octene-l are among the alpha olefins
useful in copolymerization with ethylene in this invention.
Preferably, mixtures of alpha olefins having 3 to 8 carbon
atoms are used in a preferred embodiment of this invention.
By this process, polymers generally considered to be HDPE
(densities of 0.940 or greater) and LLDPE (densities below
0.940) may be made equally well by adjusting comonomer
concentration in the feed or other factors. The amount of ¦~
comonomer needed is determined by the density of the polymer
product being made. Generally, no~ less than 0~5 vol ~ of
alpha olefin will be used ~ncl not morc than 30 vol ~ Oe th~
alpha olefin will be utllized for any given volu~ne of the gas
mixture along with any of the inert gas and between about
0.10 vol % and about 10.Q vol % of hydrogen, between about
0.0001 vol % and about 1.000 vol % chloroform, and between
about 50.0 vol ~ and about 99.4 vol ~ ethylene.
The catalyst compositions of this invention are
preferably fed to the gas-phase fluidized-bed reactor as~*r~-
particulate matter, such as dry powder under the inert gas.
Any gas that does not react with the catalyst is considered
inert. Suitable inert gases include nitrogen, argon, and
methane. Any dev1ce which can measure and convey a free-
flowing powder is suitable for feeding the catalyst, although
the device must not allow monomer to enter the catalyst
storage are~ of the feed device. Once the catalyst has b~en
measured and delivered to the catalyst feed line, any good
method of conveying it to the fluidized bed may be used.
These include mechanical means such as screw conveyers, or
gas conveying with inert gas or, as Miller teaches, with
recycle gas from the reactor. Catalyst may be added
continuously, semi-continuously, or discontinuously to the
r~actor. Continuous addition is preferred, but ls virtually
1,1
I -30-
1.~ 3~6
I ilnpossible at laboratory scale. Catalyst may be fed pure or
Il may b~ dil~lted with any free-fl~wing particulate material
such as pure, dry support or polymer powder from the reactor.
¦ In catalyst feeding, all that is ~eally critical is that the
catalyst be fed at a controlled rate and be dispersed in the
bed before a "hot spo-t" develops.
¦ The produced particulate polymerized su~stan~ially
ethylene particles may be removed from the gas-phase reaction
zone by any suitable means and at any suitable location.
Preferably, the produced ethylene polymer particles are
removed in accordance with the procedure described by Miller
in U. S. Patent No. 4,003,712. In a preferred embodiment of
the invention, the producecl ethylene polymer particles are
removcd from the gas-phase reaction zone above and in
uroximity to tho distrib~ltion pla~e.
~s has been mentioned, it is necessary to ttave good
¦ fluidization, good catalyst ~ixing, and good distribution of
~¦ gas in the bed in order to avoid l'hot spots" which cause
¦ lumps to form in the bed. These lumps themselves disturb
¦¦ fluidization so, once a lump forms, the tendancy for other
¦¦ lumps to form is enhanced. Eventually a reactor shut down is
¦necessary because the process becomes inoperable.
Similarly, i-t is necessary for long-term, stable
¦operation of commercial reactors that the surfaces of the
¦reactor and distribution plate remain clean. If a polymer
coating (fouling) builds up on a reactor surface, several
¦undesirable things may happen. First, fouling on the
¦Idistribution plate tends t~ perturb the desired gas
~,distribution and restrict the abilitytxJ~the poly~er
¦¦par-ticles at the plate to ~ove laterally. Both effects tend
!Ito produce "hot spots" at or near the distribution plate.
¦!Second, fouling on the reactor wall inhibits the normal
¦¦downward motion oE fluidized part-cles at the wall surface.
¦IParticles which "hallg up" at a wall surface can ~Jenexate "hot
'spots". Third, the wall coating may come loose in places,
I
.
il -31-
- ~,rl,'
/~ ~L2~39~6
fall into the bed, and disrupt fluidization as any lump would
do. Even worse, wall fouling usually is in the form of a
"slleet" rather than a lump, and produces severe gas
channelling in the bed if it falls off.
Although poor selection of operating conditions or
poor operating techniques may lead -to lump formation, it
appears that fouling of reactor surfaces depends primarily on j
the catalyst used. Some catalysts tend to produce J
rouling,and some do not. At this time, insufficient
experience has been gained to be able to predict wi-th r~
accuracy which catalyst compositions will foul and which will
give stable operation for months without fouling reactor
surfaces. Obviously, for economical commercial operation,
the catalyst must not Eoul reactor surfaces. Fouling in a
commercial r~clctcr l~a~ls ~o "down time" with consequen~ Loss
oE production and ~xtr;l m~int~llance cost for cleaning. Thus,
fouling will cause a gas-phase fluidized-bed process to lose
its economic advantage over slurry processes.
The following examples are given to illustrate the
invention and are not intended as a limitation thereof. In
these examples, compositions and processes that are
illustrative of the invention are distinguished from those
that are outside the scope of the invention and are included
only for comparative purposes by using an alphabetic
designation for any example or run that is a comparative
example and a numeric designation for the examples and runs
that are illustrative of the invention. Yields given in the
examples are measures of productivity in terms of the number
of grams of polymer produced per gram of catalyst per hour,
melt indices (MI2)~are those determined by ASTM test
D-1238-65T using a 2160-gram weight, while the NVR values are
"normalized" melt viscosity ratios determined by measuring
the apparent viscosi-ties of the polymers at 30 sec 1 and 300
sec. 1, respectively, at 200 C. in an Instron caplllary
rheometer and (2) normalizing them to V30=5 by the equation.
NVR=antilog (0.14699~0.7897 log V30 - log V300)
I
i -3~
3~3~3~j l
I where v30 and V300 are the measured apparent viscosities.
I This normalization permits comparison o the viscosity ratios
l of polymers having different V30 values, since the
unnormali~ed V30/V300 ratio is a function of V30. The NVR is
constant for any given catalyst over an MI2 range of about
30, and only slight deviations occur outside of that range.
In the examples, the following procedures are used
to prepare -the catalyst compositions and polymers.
I PREPARATION OF CATALYSTS
¦¦ In the preparation of each of the catalysts, dry a
I commercial inorganlc oxide by heating it under d~y,
deoxygenated nitrogen for 5-16 hours at a tempera-ture of 200
¦ -600 C. to provide an activated oxide containing about 1 -
~1 1.4 mmols of available hyclroxyl yroups per gram. Cool the
¦l activatecl oxide to ambient l:emperature under a purifiecl
nitrogen blanket, suspend it in commercial hexane, add neat
,l organometallic compound, and stir the resultant slurry for
30-60 minutes. Then add a vanadium compound in neat or
solution form, stir the resultant slurry for an additional
30-60 minutes, add an alcohol~ stir for another 30-60
minutes, and remove the hexane under a nitrogen purge to
!produce a powdered solid catalyst. The particular
¦lingredients used to prepare the catalysts, the amounts of
llorganometallic, vanadium, and alcohol compounds added per
¦¦gram of inorganic oxide, and the particular temperatures used
¦to dry the inorganic oxides are shown in the examples and/or
tables.
I ~ro~,g~
I -$~e~h ou~ the examples the commercial magnesium
;oxide used m Merck Maglite D, ~ inorganic oxide having a
¦Isurface area of about 150-200 square meters per gram, a pore
Ijvolume of about 1.2-1.5 cc per gram, and an average particle
¦Is ze of about 30 - 40 microns; the cornmercial silica employed
~nrDavison 952 silica gel, an inorganic oxide having a
~surface area of about 250-350 square meters per qram, a pore
volume of about 1.5-1.7 cc per gram, and an average particle
33-
,~,
/~ ~2~39~36 lll
! size of about 65-75 microns; the commercial alumina is Norton
G376, an inorganic oxide llaving a surface area of more than ~i~
100 s~uare meters per gram and a pore ~d~of about 0.8-1.1
`I cc per gram; and the commercial aluminum silicate and
i¦ magnesium silicate are ~. R. Grace's materials haviny the
designations XSZ-AL-65C and XSZ-MG-66C, respectively.
!~ SLURRY POLYMERI ZATION
¦ Charge 1.5 liters of dry hexane to a suitable
autoclave under a dry, deoxygenated nitrogen atmosphere, add
i 2.1 mmols of triethyaluminum as ~ activator-scavenger, stir
,1 ~or 5 minutes, and add a slurry of 0.1-0.4 gram of catalyst
I¦ powder in, respectively, 1-4 ml of commerical hexane. Raise
the temperature of the reactor -to 85-90 C., add enough
hydrogen to ensure the production of a polymer having a
molecular weight such that its MI2 will be within the range
¦ of about 1-30, raise the reactor pressure to about 2.1 MPa
I with ethylene, and any comonomer(s~ being employed, and hold
¦ the pressure at that level throughout the po~ymerization by
¦ adding monomer as needed. Immediately after pressurizing the
reactor with monomer, add 0.17 mmol of chloroform as a
l promoter; and, at 15-minute intervals thereafter, add
¦ supplemental 0.17 mmol aliquots of the promoter. After one
hour, stop the polymerization by venting the autoclave,
opening the reactor, and iltering the polymer from the
liquid medium, and drying the polymer. Then dry the polymer
under vacuum at 60 C for 4 hours.
LABORATO~Y GAS-PHASE POLYMERIZATION
The laboratory apyaratus consisted of a continuous
¦polymerization reaction system essentially as depicted by
¦ Miller in the drawing of ~.~S. Patent No. 4,003,712, with two
¦exceptions: there was no filter in the gas recycle line, and
llthe catalyst was Eed to the reactor with nitrogen only. The
¦Ireaction zone was 10 cm in diameter, 120 cm tall. Recycle
jllgas passed through a velocity reduction or disengaging zone
¦latop the reactor, through a cyclone separator, through a
! centrifugal compressor and into the bottom of the reactor
-3~-
1 ~26399~
I where the gas was distributed into the fluidi~ed bed by a
l clispersion or distributiorl plate. fleat exchange was effeeted
I Pressu r~z~d
I by circula~ing~ ~Y~e~ tempered water through jacketing
on the recycle gas piping. This system had a rated capacity
of ~}50 g of polymer per hour. Generally, for catalyst
screening studies, the system was opera-ted as follows:
¦l Introduce a stream or streams of ethylene,any
¦¦ comonomer(s), chloroform, and hydrogen to the reactor.
¦ Continuously withdraw unreacted or recycle gas from the top
'l of the disengaging zone, pass it through a heat exchanger to
¦~ maintain a bed temperature of about 95-100 C., and
¦l introduce it at the bottom of the reactor at a rate
¦I sufficient to give a superficial veloeity of about 25 em/sec
in the bed.
troduc~ mak~-up monomer, ehloroorm, and hydrocJe
into the recycle gas line so as to maintain eonstant gas
composition as detected by on-line analyzers and so as to
¦I maintain the reaetor pressure at about 3.5 MPa and to provide
¦ about 40 mmols of ehloroform per mmoi of vanadium per hour,
¦l and feed fresh catalyst partieles into the reaetor below the
¦top of the bed so as to provide a vanadium feed rate of cne
mmol per hour. Add triethylaluminum as a seavenger and
coeatalyst during the polymerization so as to provide a
triethylaluminum feed rate of 20 mmol per hour. Withdraw
polymer produet semi-eontinuously from the bottom of the bed
at a rate such as to maintain a constant bed level. Take
¦ aliquots of withdrawn polymer for testing.
I EXAMPLE I
¦I Prepare five eatalyst eompositions by the eatalyst
¦¦preparation proeedure described above, exeept for ~Ising no
¦aleohol in the preparation of the first eomposition. In eaeh
1l case, employ MgO as the inorganic oxid~, trie~hylalulninunl as
'Ithe organometallie eompouncl, ethoxyvanadium oxydichloride as
¦¦the vanadium eompound, and ethanol as the aleohol, when
!lemployed; and dry the support at about 200 C. Use each of
lil
-35-
;3~3~3~;
~ill ~ompoS ~t'n~
/ llthe cat~lyst CG.~ ti~n to prepare polyethylene by the
/ Islurry polymerization procedure described above. The amounts
/ If ingredients employed in the production of the catalyst
/ composltions, and the yields, melt indices, and normalized
l viscosity ratios (NVR), i.e., molecular weight distributions,
i of the polymers are shown in Table I
TABLE I
Run # Catalyst Composition Yield MI2 ~VR
I _
/Al(c2H5)3/Mgo70 g l.0 2.29
0.2 mmol l.0 mmol 1 9
1 C2~l5O~I/(C2~lsO)VOCl2/lO~ g ~.6 2.25
Al(C2ll5)3/M9O
0.2 mmol 0.2 mmol l.0 mmol l g
¦ 2 C2~l5OH/~C2H5O)VOC12/ 85 g 2.5 2.14
ll Al(C2H5)3/Mg
il 0.5 mmol 0.2 mmol 1.0 mmol 1 g
3 C2H5O~/(c2Hso)vocl2/ 4.1 2.10
Al(c2H5)3/Mgo
1.0 mmol 0.2 mmol 1.4 mmol l g
4 C2ll5O~I/(Cz~5O)VOCl2/138 g ~.2 2.06
Al(C2H5)3/M~
I ¦ 1.4 mmol 0.1 mmol 1.4 mmol l 9
I _ _
; I As demonstrated above, the addition of ethanol, as
the last-added component, with an ethoxyvanadium
oxydichloride/triethylaluminum/magnesium oxide catalyst
composition results in the formation of a catalyst
composition that narrows the molecular weight distribution of
polymers ~ormed in its presence - this narroWlng of 'che
molecular weight distribution being progressive as the amount
I of ethanol used is increased from 0.2 to l.0 per mol of
~¦ triethylaluminum. The following example shows that polymers
63~j '11
having narrow molecul~r weight distributions c~n also be
obtained when an alkylaluminum alkoxide is substituted for a 11
trialkyla1uminum in the practice of the invention
EXAMPLE II t
Prepare a catalyst composition by the catalyst It
preparation procedure described above, usin~ MgO as the
inorganic oxide, drying it at about 200 C., and sequentially
reacting with 1.0 mmol of diethylaluminum ethoxide, 0.2 mmol
of ethoxyvanadium oxydichloride, and 1.0 mmol of ethanol per
gram of silica. When the catalys~ composition is used to
prepare polyethylene by the slurry polymeriza-tion procedure
described above, the process results in the production of 80
grams of polymer having a melt index of 3.0 and an NVR value
of 2.12.
EXAMPI,E III
Prepare two C~30~ n-Clg~l37O)VOC12/ ( 2 5 3 2
catalyst eompP~s-}t-~e~ by the catalyst preparation procedure ~¦
described above, employing the same amounts oE ingredients in
each case, i.e., 1.5 mmol of triethylaluminum, 0.2 mmol of
n-octadecoxyvanadium oxydichloride, and 1.0 mmol of methanol
per gram of silica, but using a drying temperature of about
200 C. for the sillca used in producing the first of the
compositions and a drying temperature of about 550 C. for
the silica used in producing the second of the compositions.
Then use each of the catalyst compositions to prepare
polyethylene by the slurry polymerization procedure described
above~ The yields, melt indices, and NVR values of the
polymers are shown in Table II.
TABLE II
_.
¦ Run # Support Dry~ng Temp. Yield MI2 NVR
Il
200 C. 170 g 5.4 2.34
6 550 C. 198 g 4.6 1.99
37~
399 Ei 11
I The preceding example and the following three
l examples show that the use of different inorganic oxides,
¦ different alkoxyvanadium compounds, and different alcohols
I which may or may not have the same chain length as the alkoxy
l groups of the vanadlum compounds employed, as well as the use
of diEferent support drying temperatures, are permissable
within the scope of the invention and lead to the formation .
! of catalyst compositions that can be used to prepare polymers
! having narrow-to-intermediate molecular weight distributions.
l These examples also show that, in general, narrower molecular
¦¦ weight distributions are obtained when the catalysts used in
the preparation of ethylene polymers are formed by the use of
supports that have been dried at the higher temperatures
within the preEerred range of drying temperatures taught in
, the speciflcation.
EXAMPL~ tV
I Prepare three n-C8~l17~l/(n C8~17 ) 2
Al(C2H5)3/SiO2 catalyst compositions by the catalyst
¦preparation procedure described above, employing the same
amounts of ingredients in each case, i.e., 1.4 mmol oE
triethylaluminum, 0.2 mmol of n-octoxyvanadium oxydichloride,
and 1.0 mmol of n-octanol per gram of silica, but using
. different dryiny temperatures for the silica used in
¦producing each of the compositions, i.e., 200 C., 350 C.,
¦and 550 C., respec-tively.` Then use each of the catalyst
,I!compositions to prepare polyethylene by the slurry
,¦polymerization procedure described above. The yields, melt
indices, and NVR values of the polymers are shown in Table
IIIII.
TABLE III
I,Run # Support Drying Temp. Yield MI2 NVR
11
il7 200 C. 55 g 1.8 2.32
8 350 C. l46 g 2.1 2.~1
ilg s5oo C. 320 g 20.2 l.9S
~ 38-
39'36
I EXAMPLE V
I Prepare two n-c~ 7oH/(n-c~Hl7o)vocl2/Al(c2~l5)3/
~¦ A12O3 catalyst compositions by the catalyst preparation
¦ procedure described above, employing the same amounts of
¦ ingredients in each case, i.e., 1.4 mmol of triethylaluminum,
1 0.2 mmol of n-octoxyvanadium oxydichloride, and 1.~ mmol of
¦ n-octanol per gram of alumina, but using~a drying temperature
of about 200 C. for the alumina used in producing the first
of the compositions and a drying temperature of about 550 C.
for the alumina used in producing the second of the
compositions. Then use each of the catalyst compositions to
Il prepare polyethylene by the slurry polymerization procedure
¦I described above. The yields, melt indices, and NVR values of
~ the polymers are shown in Table IV.
I T~\BLE IV
l _ _
~¦ Run # Support Drying Temp. Yield ~I2 NVR
200 C. 47 9 6.9 2.16
11 550 C. 83 g 11.6 1.65
¦ EXAMPLE VI
~ pare two nac8~ll7oH/(n-c8Hl7o)~ocl2/A ( 6 13 3
A12O3 catalyst compositions by the catalyst preparation
jl procedure described above, employing the same amounts of
¦ ingredients in each case, i.e., 1.5 mmol of
tri-n-hexylaluminum, 0.2 mmol of n-octoxyvanadium
oxydichloride, and 1.0 mmol of n-octanol per gram of alumina,
but using a drying temperature of about 200 C. for the
alumina used in producing the first of the compositions and a
drying temperature of about 500 C. for the alumina used in
i producing the second of the compositions. Then use each of
the catalyst compositions to prepare polyethylene by the
slurry polymerization procedure described above. The yields
melt indices, and NVR values of the polymers are shown in
Table V.
!~
~1 ~39~
;3~:396
~I ill
¦l TABLE V
11 ;I,i
/ IlRun ~ Support Drying Ternp. Yield MI2 NVR
~ _ - ~h
12 200C. 48 g - 1.91 , ,
13 500 C. 355 9 18.6 1.67
As demonstrated above, particularly when ~12 of
this example is compared with Run ~10 of the preceding
example, the substitution of a higher trialkylaluminum for a
lower trialkylaluminum in preparins -the catalyst compositions
of the invention can lead to a narrowing of the molecular
weight distribution of polymers formed in the presence oE the
catalyst compositions when all ~ther factors are
substantially constant.
EXAMPL~ VII
Prepare three n-c8~1L7o~l/(n-c8Ell7o)vocl2/
"p o~ 'vn ~
Al~C6lll3)3/inorganic oxide catalyst-eem~e~tio~ by the
catalyst preparation procedure described above, employing the
same amounts of ingredients in each case, i.e., 1.4 mmol of
tri-n-hexylaluminum, 0.1 mmol vf n-octoxyvanadium
oxydichloride, and 0.25 mmol of n-octanol per gram of
inorganic oxide, and drying the support at about 250 C. in
each case, but using different inorganic oxides as the
supports, i.e., silica, magnesium silicate, and.aluminum
silicate, respectively. Tllen use each of the catalys-t
compositions to prepare polyethylene by the slurry
polymerization procedure described above. The melt lndices
and NVR values of the polymers are shown in Table VI.
TABLE VI
I
I Run # Inorganic Oxide Support MI2
_ _ __
14 silica 11.9 1.97
magnesium silicate8.7 1.76
¦ 16 aluminum silicate11.9 1.66
11 .
4 0-
39~3
~ I This example shows that mixtures of inorganic
/ oxides are also useful as supports for the catalyst
/ I compositions of the invention and can, in fact, be
¦ par~icularly desirable supports.
! The following two examples demonstrate -that the
¦ reaction of the inorganic oxide with substantially less than
a stoichiometric amount of the organometallic compound leads
I¦ to the formation of polymers having broader molecular weight
'I distributions when the catalyst compositions are used in
¦ polymerization reactions, and reaction wi~h an amount of
. organometallic compound considerably in excess of the
stoichiometric amount - although also useful in the
preparation of catalyst compositions capable of being
l ut.ilized in the production o injection molding-grade
1 po.l.ym~rs - ofEers rlo NVR advantage over th~ use o~ a
~¦ substantlally stoichiometr.ic amount of the organometallic
,j compound.
, EXAMPLE VIII
Prepare three n-C6H13OH/ (n C18 37 2
l Al(C6H13)3/SiO2 catalys-t compositions by the catalyst
¦¦ preparation precedure described above, drying the silica gel
at about 200 C. in each case and employing the same arnounts
of alcohol and vanadium compound, i.e., 1.0 mmol oE n-hexanol
Il and 0.2 mmol of n-octadecoxyvanadium oxydichloride per gram
il of silica, but varying the amount of tri-n-hexylaluminum
: 1l used. Then use each of the catalyst compositions.to prepare
¦! polyethylene by the slurry polymerization procedure described
¦ above. The yields, melt indices, and NVR values of the
polymers are shown in Table VII.
¦ TABLE VII
Il Run # mmol AlR3/g SiO2 Yield MI2
Ij -
B 0.8 45 9 1.0 2.54
j 17 1.5 74 9 8.3 1.76
18 2.25 250 g - 1.7
.1
'I -41-
i3'3~3
/ I
/ ¦ EXAMPLE IX
Prepare three n-C8~ll7O~I/(n C8 17 2
1 Con1p~s~fl'0n~
Al(C2H5)3/SiO2 catalyst-e~m~i~i~ by the ca-talyst
preparation procedure described above, drying the silica gel
at about 550 C. in each case and employing the same amounts
l of alcohol and vanadium compound, i.e., 1.0 mmol of n-octanol
i,l and 0.2 mmol of n-octoxyvanadium oxydichloride per gram of
¦ silica, but varying the amount of triethylaluminum used.
! Then use each of the catalyst compositions to prepare
polyethylene by the slurry polymerization procedure described
above. The yields, melt indices, and NVR values of the
polymers are shown in Table VIII.
TABLE VI I I
l __.
Run ~ mmol AlR3/g SiO2 Yield MI2 NVR
C 0.8 48 g ~.S 2.58
D 0.8 55 g 1.4 2.78
19 1.5 320 g 20.~ 1.95
¦ EXAMPLE: X
Prepare two catalyst compositions by the catalyst
preparation procedure described above to -test the utility of
dialkoxyvanadium compounds in the practice of the invention.
Use each of the compositions to prepare polyethylene by the
sIurry polymerization procedure described above. The yields,
ii melt indices, and NVR values of the polymers obtained by the
use of each of the catalyst compositions are shown in Table
IX.
TABLE IX
_ _ .
Run# Catalyst Composition Yield MI2 NV~
_
C2H5OH/(C2H5O)2VOCl/
l Al(C2H5)3/Mg 152 g 31 2.07
! l.o mmol 0.2 mmol 1.0 mmol 1 g
¦1 21 C6H13Otl/(cl8H37o)2
¦ VCl/Al(C6H13)3/Si2 281 g 4.7 1.7
~¦ 1.0 mmol 0.1 mmol 1.5 mmol 1 g
3~
/ , EXAMPLE XI
/ Prepare a catalyst composition by the catalyst
/ preparation procedure described above, using silica gel as
¦ the inorganic oxide, drying it at about 200 C., and
I sequentially reacting with 1.5 mmol o tri-n-hexylaluminum,
;¦ 0.1 mmol of vanadium oxytrichloride, and l.0 mmol of
~I n-hexanol per gram of silica. When the catalyst composition
¦¦ is used to prepare polyethylene by the slurry polymerization
¦¦ procedure described above, the process xesults in the
production of 196 grams of polymer having a melt index of
¦1 12.5 and an NVR value of 1.86.
EXAMPLE XIII
Prepare three catalyst compositions by the catalyst
preparation procedure described above, except or using no
alcohol in the preparatiorl Oe the first compos~tion. In e~ch
case, employ SiO2 as the inorganic oxide, triethylaluminum as
I the vanadium compound, and n-hexanol as the alcohol, when
j employed, and dry the support at about 250 C. Use each of
¦ the catalyst compositions to prepare polyethylene by the
~¦ slurry polymerization procedure described above. The number
I of mmols of triethylaluminum, vanadium tetrachloride, and
n-hexanol employed per gram of silica in the production of
the catalyst compositions, and the yields, melt indices, and
NVR values of the polymers are shown in Table X.
TABLE X
: I . `.
¦ Run # Catalyst Compositlon Yield MI2 NVR
_
¦ ~ vcl4/Al(C2H5)3
: 1l /SiO2 2366 9 0.3 2.34
0.2 1.5
: 22 C6Hl3oH/vcl4
: I /Al(C2H5)3/sio2227 g 1.7 2.17
0.15 0.05 1.4
23 C6Hl3OH/vcl4/Al(c2H5)3
/SiO2 1007 g 0.4 2.01
0.5 0.2 1.5
l _ _ _ _ _ _
~ 43_
3~3~3~ ~1~
Examples X-XIII demonstrate the utility of vanadium
conl~oullds other than alkoxyvanadium oxydichlorides in the
practice oE the invention.
¦I EXA~PLE XIV
j 6 130H/(C18~370)VOC12/Al(C6H13) 3/sio
¦I catalyst composition by the catalyst preparation procedure
described above employing 1.5 mmol of tri-n-hexylaluminum,
0.1 mmol of n-octadeco~yvanadium~ oxydichloride, and 1.0
mrnol of n-hexanol per gram of silica. For comparative
,I purposes, prepare five other catalyst compositions from the
¦¦ same amounts of the same inyredients, and use the same drying
!I temperature for the silica as was used in the preparation of
Il the first of the compositions, but varyiny the order of
¦¦ addition of the catalyst components to determine the
criticallty o~ that ord~r o addition. Therl u6e each oE the
I catalyst compos:itions to prepare pol~ethylene by ~he slurry
~! polymerization procedure described above. The catalyst
~¦ compositions and the melt indices and NVR values of the
i¦ polymers are shown in Table XI, which, llke the earlier
Tables, lists the catalyst components in the reverse order of
¦ addition, i.e , the last-added component beiny the first
list~d as one reads from left to riyht.
I¦ TABLE XI
I
~ Run ~ Catalyst Composition MI2 NVR
, : _
¦ 24C6H130H/(ClgH370)VOC12/Al(C6~13)3 2
( 6Hl3)3/c6Hl3oH/(clgH37o)vocl2/sio2 -- 2.51
,I G6 13oH/Al(c6Hl3j3/(clgH37o)vocl2/siQ2 ~~ 2.81
I ¦ H~ (Cl8H37o)vocl2/c6Hl3oH/Al(c6 13 3 2 2.44
I(~l8H37o~vocl2A~(c6Hl3)3/c6Hl3 / 2 2.88
( 6~l3)3/~cl8H37o)vocl2/c6~l3oH/sio2 1.5 2.38
I
As demonstrated above, catalyst compositions
prepared from the same components as the catalyst
l compositions of the invention do not have the same
i effectiveness in narrowing the molecular welght distributions
.,
Il,
j -44-
/~ ~X4:~3'~t3~3~j .
of polymers prepared in their presence when the catalyst
components are combined in a different order.
Each of the preceding examples illustrates the
utility of catalyst compositions of the invention in slurry
polymerization processes. The following -two examples
demonstrate their utility in gas-phase polymerization
reactions.
EXAMPLE XV
Use the catalyst composition of Example I, Run # 3,
to prepare polyethylene by the laboratory gas-phase
polymerization procedure described above. The reaction
temperature employed for the polymerizations and the melt
indices and NVR values of the product are shown in Table XII.
There was no evidence of reactor fouling.
TA~LE XII
E~un ~ Temperature MI2 NVR
_
99 C. 40 2.08
26 99 C. 7 2.02
27 88 C. 6 2.14
28 88 C. 3 2.16
I :
¦ EXAMPLE XVI
~se the catalyst composition of Example VIII, Run
¦ #17, to prepare polyethylene by the laboratory gas-phase
polymeri~ation procedure described above. The ~elt indices
¦ and NVR values of the products are shown in Table XIII.
¦~ ~There was no evidence of reactor fouling.
TABLE XIII
I ~
Run # MI2 NVR
l : - , _.
29 10.8 1.89
24.l 1.88
31 7.7 1.~5
I _ _
!
1,l
ll -A5~
4~
1~i39~3~i
/!1
~ EXAMPLE K
I An attempt was made to essentially repeat Example
'¦ III of U.S. Pat. No. 4,232,140 using the laboratory gas-phase
polymerization method described above with Ort's catalyst and
CFCl3 promoter, operating the equipment contlnuously 24 hours
a day. After two days, and before the reaction had lined out
Il sufficiently to get a good sample of the desired product for
il comparison with the products made by the catalysts of this
¦¦ invention, the reactor became inoperable. After the reaction
¦I system had been shut-down, the reactor was opened. The
~¦ reactor walls and distribution plate were found to be fouled
!l (coated with polyrner) to the extent that normal fluidization
¦¦could not be maintained.
The reactor was thoroughly clearled, al~d the attempt
rep~a~ed. ThLs t;im~, ~h~ reactor "ouled out" in about o~le
¦¦clay. A third att~mpt to run this catalyst and CE'C13 promoter
on a continuous basis was similarly unsuccessful. This
l example shows that long term operability of a gas-phase
! fluidized bed depends upon proper choice of catalyst and
'il promoter.
The foregoing examples illustrate the utility of
thc invcntiorl in tl~e ~re~a~ation vf hig~l dellsity polyct~lylcn~
which typically have dcnsities of at least 0.~65 g/cc. Th~
following exampl~s illustrate its utility in the preparation
~ of-~h~y~e~e polymers having lower densities.
;: ¦! EXAMPLE XVII
j Prepare two catalyst compositions by the catalyst
preparation procedure described above, using magnesia as the
¦ inorganic oxlde in each case, drying it at about 200 C., and
¦ sequentially reacting it with 1.4 mmol of triethyaluminum,
0.2 mmol of an alkoxyvanadium oxydichloride, and 1.0 mmol of
Il an alkanol per gram of magnesia. Then use each of the
¦Icatalyst composi-tions to prepare an ethylene copolymer by the
~¦slurry polymerization procedure described above, employing 30
cc o~ liquid butene-l as the comonomer in each case. The
catalyst compositions and the melt indices, NVR values, and
Il
/ I densities of the polymer are shown in Table XIV.
/ ¦ T~BLE XIV
/ il Run ~ Catalyst Composition MI2 NVR Density
~' i
¦ 32 C2H5H/(C2H5)VC 2/ 20 2.00 0.960
A1(C21t5)3/MCJo
33 C4HgH/(C~H9)vcl2/ 1.4 1.95 0.956
¦ Al ( C 2 H 5 ) 3/Mg
EXAMPLE XVIII
Prepare two catalyst compositions by the catalyst
preparation procedure described above, using silica as the
inorganic oxide in each case, drying it at about 550 C., and
~qu~ntlally reacti~lg lt with 1.4 mmol of triettlyla:lum.inllm,
0.2 mmol of an alkoxyvanadiwn oxydichloride, and 1.0 mmol o~
an alkanol per gram of silica. Then use each of the
catalyst compositions to prepare an ethylene copolymer by the
slurry polymerization procedure described above, employing 40
cc of liquid butene-l as the comonomer in each case. The
CO~o~ o5~'~;0 n
catalyst e~m~t-i~n a~d -the melt lndices, NVR values, and
densities of the polymers are shown in Table XV.
TABLE XV
Run # Catalyst Composition MI2 NVR Density
_ .
34 C8H17OH/~c8Hl7o)vocl2/ 52.6 2.05 0.948
Al(c2H5)3/sio2
CH3H/(C18H37)VC12/ 17.3 1.85 0.952
Al(c2H5~3/slo2
~ ~ , , __ _. _
¦ EXAMPLE XIX
il Prepare two catalyst compositions by -the.catalyst
¦ preparation procedure described above, using alumina as the
Il inorganic oxide in each-case, drying it at about 550 C~ in
jl the case of the catalyst composition to be used in ~un # 36
I; and at about 500 C. in the case of the catalyst composition
,1 -47~
/ ¦ to be used in Run #37, and sequentially reacting it with l.S
/ I mmol of trialkylaluminum, 0.2 mmol of n-octoxyvanadium
/ ¦ oxydichloride, and l.0 mmol of n-octanol per gram of
~ 11 alumina. Then use each of the catalyst compositions to
J ~l prepare an ethylene copolymer by the slurry polymerization
¦ procedure described above, employing 40 cc of liquid butene-l
as the comonomer in each case. The catalyst compositions and
the melt indices, NVR value and densities of the polymers are
show in Table XVI.
l ,
TABLE XVI
I .
l Run # Catalyst Composition MI2 NVR Density
i
6 C~lll7o~l/(cg~ll7o)vocl2/
~1(C2~ls)3/A12 3 16.3 I.75 0.955
37 C8~l17~l/(c~Jll7~jvocl2/
Al(C6~ll3)3/~l2o3 67.8 1.63 0.9S5
l _
¦ EXAMPLE XX
j, ~se the catalyst composition of Example XIII, Run
#23, to prepare an ethylene copolymer by the slurry
polymerization procedure described above, employing 100 cc of
liquid butene-l as the comonomer. The process results in the
production of 1007 grams of an ethylene/butene-l copolymer
having an NVR value of 2.01 and a density of 0.937.
l EXAMPLE XXI
¦ I Use the catalyst of Example XI to prepare an
~¦ ethylene copolymer by the slurry polymerization procedure
I described above, utilizing 40 cC of liquid butene-l as the
¦ comonomer. The process results in the production of 283
grams of an ethylene/butene-l copolymer having an MI2 of 11.4
and an NVR value of 2.17.
EXAMPLE XXII
A batch of catalyst having the composition 1.4 mmol
¦ triethylaluminum, 0.2 mmol VCl4, 0.5 mmol n-octanol per gram
Sio2 was prepared as a dry powder according to the general
-48-
~ ~ i39~
~/ I procedure of Rogers, U.S. 4,426,317. Gas phase
¦ copolymerizatioll was carried out in a small pilot plant
Il similar in design to the laboratory gas phase reactor except
¦¦ that there was no separator in the gas recycle line. The t~
reactor had a reaction zone 30 cm in diameter, about 2 m
tall. This run was conducted at 2.0 ~IPa and~ e}~ees C
I '~
average bed temperature with a recycle gas flow of about 1100
i kg/hr which gave a gas velocity ln the bed of about 30
cm/sec. The recycle gas stream consisted essentially of
84.4~ ethylene, 3.8% ~ydrogen, 9.3~ butene-l, and 2.5~
nitrogen. Catalyst was added with nitrogen to the fluidized
¦ bed at an average ra-te of 7.5 cc/hr, triethylaluminum ~TEA)
~'1 was added as a 10% solution in hexane at a rate of 4.9 cc/hr,
!! and chloroform was added at a rate of 1.4 cc/hr. A film-grade
¦¦ polyrner having a melt index of 1.4, a density of 0.934, and a
i¦ total ash content of 600 ppm was produced at an average rate P
¦¦ of about 7 kg/hr during 8 hours oE steady op~ration.
I¦ EXAMPL~ L
¦j ~t the conclusion of Example XXII, the hydrogen
feed is discontinued while everything else is maintained
¦ essentially unchanged. Gradually, the hydrogen/ethylene
li ratio drops, as determined by an on-line gas analyzer, as
¦~ recycle gases are lost from the reaction zone through purge
Il to the instruments and by being removed with the polyethylene
¦¦ product, with no fresh hydrogen being added to the make-up
gases. As the hydrogen level in the recycle gas decreases,
il the polymer melt index drops until it is unmeasurably low.
j The polymerization rate, as determined by ethylene uptake and
j by product removal from the reaction zone, is unchanged
within experimental error. Thcre is no external evidence of
reactor fouling. Hydrogen flow is then restarted, and the
original hydrogen/ethylene ratio re-established. Within 18
hours, the melt index is again 1.4 and the polymer is again
useful for fil~
r;,i 11
'3~3~;
The chloroform feed is then discontinued, all other ;
variables being held as constant as possible. Gradually, the
CI~C13/V ratio decreases as the CIIC13 concentration in the
recycle gas becomes lower due to loss of recycle gas from the
system and the make-up gases being promoter-free. There is
no significant change in the melt index of the polymer, but
the polymerization rate drops and the ash content of the
polymer increses to about 3000 ppm, too high for good quality
film. The chloroform feed is then restarted at its original t
feed rate. Polymerization rate picks up immediately, as
judged from an increase in both bed temperature and polymer
powder production, and reaches a level of about 10 kg/hr,
after which the rate slowly declines and lines out at about 7
kg/hr. About 36 hours aEter chloroorm is readmitted to the
reaction, ~he reactlorl àncl polym~r are restab:Lized at the~
original conditions and the polymer is again useEul for film.
Then the triethylaluminum feed is stopped, all
other variables being held as constant as possible. The
polymerization rate begins to decrease, slowly at first, and
then rapidly. The ash content of the polymer increases
correspondingly. When the polymerization rate reaches about
1 kg/hr, the reaction is terminated intentionally, and the
reactor opened for inspection. There is no visible coating
or fouling on the distribution plate or reactor walls.
This example illustrates ~n~trialkylaluminum,
chloroform and hydrogQn, in the proper proportions, are
essential to useful practice of this invention.
EXA~IPLE XXIII
The general procedure of Example XXII was repeated
except that the catalyst had the formulation of the catalyst
of Example XIII run 22 and propylene was the colnonomer.
Polymerization pressure was about 2.1 MPa, and average bed
temperatures were in the range of 78 - 82 degrees C. The
other run conditions and corresponding polymer properties
obtained are given in Table XV. Each run in Table XV
1,1
,1 -50-
12~;.1'3')~
I represents a different condition of reasonably stable,
¦ operation during a 7-day period of continuous operation. At
¦ the end of the 7-day period, the reactor was shut down by
¦j failure of the polymer withdrawal system. There was no
¦¦ evidence of fouling of reactor walls or the distribution
plate.
TABLE XV
Il _ I
ll Run # 38 39 40 41 42 l
l . ~ l
Recycle gas composition:
Ethylene 61.663.0 68.0 58.9 61.0
! % Hydrogen 1.1 1.5 1.3 1.0 1.0
% Propylene 12.411.4 7.4 11.9 11.4
% Nitrogen 24.924.1 23.3 28.2 26.6
¦ % Chloroform 0.007 0.00980.0073 0.012 0.015
I
Flow Rates:
¦ Catalys~ (cc/hr) 5.3 4.6 2.6 3.3 3.8
TE~ (cc/hr) 3.1 3.0 3.7 3.6 3.9
Production (kg/hr) 2.1 3.4 1.5 2.0 2.2
Polymer properties:
MI (dg/min) 1.1 0.87 0.76 0.90 0.48
l Density (g~cc) 0.916 0.917 0.920 0.919 0.915
¦ Ash, ppm 390 367 340 347
¦ V residue, ppm 1.6 0.9 1.1 1.1 1.1
_
EXAMPLE XXIV
Three samples of narrow molecular weight
I ¦ distribution ethylene copolymers were made in a larger
¦ gas-phase fluidized-bed pilot plant polymerization system.
The reaction zone was 46 cm in diameter and about 3 m tall.
¦l It was topped by a disengaging zone of 92 cm diamerer. Gas
~¦ recycle piping led from the disengaging zone through a heat
exchanger and recycle gas blower to the bottom of the
reactor. A distribution plate at the bottom of the reactor
,I served to disperse or distribute the gas evenly at the bottom
¦¦ of the bed. Gas analyzers monitored the gas composition of
!~ the recycle system and, via suitable instrumentation~
~¦ automatically adjusted flows of Eeed streams to keep th~ 'J~
Il I
~ `51-
33~36
~ 11
composition constant Catalyst was fed directly to the bed
with an automatic catalyst feeder using nitrogen as the
motive gas to convey the ca-talyst into the bed.
Triethylaluminum ~TEA) was pumped directly into the bed.
Polymer powder was automatically withdrawn to maintain a
constant inventory of powder in the reactor. Eor all three
samples, reaction pressure was about 3.5 MPa, average bed
temperature ws about 92 degrees C, and the recycle gas rate
was about 4525 kg/hr, which gave a gas velocity in the bed of
crf~ .
abou-t 30 ~/sec. Average reaction conditions during the time
each sample was collected and results for each sample are
given in Table XVI.
Catalysts for these runs were made essentially as
taught by Rogers in U.5. 4,~26,317. For runs 43 and 44, the
cataLyst contpo5ition was 1.5 mmol tri-n-hcxylalum:irlulll, 0.1
rllmol n-octad~cyloxyvancldLurn oxydichloride and 1.0 mmol
n-hexanol per gram of dry silica support. For run 45, the
catalyst had the composition of 2.25 mmol
tri-n-hexylaluminum, 0.2 mmol n-octadecyloxyvanadium
oxydichloride and 1.0 mmol n-hexanol per gram of dry silica.
There was no evidence of reactor fouling after any of the
runs.
,
-52-
i3~396
~ ~ ~ TABLE XVI
. ~ igl ~ _ .
¦ Run ~ 43 44 45
Recycle Gas Composition:
Nitrogen 5.6 5.9 6.8
I ~ Ethylene 86.185.1 84.8
i % ~ydrogen 4.4 5.1 5.3
, % Propylene 3.9 3.9 3.1
¦ ~ Chloroform 0.0700.085 0.080
Other Poly~erization data:
Al/V ratio 42 29 26
~/3/~eHe~- ratio 123 305 112
Production (kg/hr) 15 13 13
Polymer properties:
I MI (dg/min) 2.2 q.5 2.1
~ Density (y/cc) 0.9530.954 0.9Sq
I ~h,ppm 702 699 323
V residue, ppm 2.9 3.1 2.9
_
EXAMPLE XXV
A commercial gas-phase fluidized-bed polyme~rization
¦ is carried out in a polymerization system of the same general
¦ description as the pilot plant of example XXIV. `However, the
reaction zone is 3.6 m in diameter and about 15 m tall.
Recycle gas rate is sufficient to give a gas velocity in the
bed of about 30 cm/sec The polymerization is conducted at
3.5 MPa pressure and 93 degrees C average bed temperature
with a feed stream targets of 6.0 ~ ~ nitrogen, 85.0
ethylene, 3.9 % propylene, 5.1 ~ hydrogen, and 0.07 ~
I chloroform. The catalyst has the formulation 1.4 mmol
¦¦ triethylaluminum, 0.1 mmol undecyloxyvanadium oxydichloride,
¦ 1.0 mmol n-octanol and is made in commerclal batches of 4S0
~ kg each. The Al/V ratio during polymerization varies
¦~ slightly as monomer purity varies, but is in the range of 10
Il to 30.
¦¦ The polymer, producted at a rate of about 8.5
me-tric tons per hour, is an injection molding grade, has an
-53-
_- !
3~3~3~
average melt inde~ of 5, an average density of Q.954, and an
NVR of 1.9 plus or minus 0.1 This product is made in
commercial runs of two weeks or longer without evidence of
reactor fouling.
Similar results in the narrowing of the molecular
weight distributions of ethylene polymers are obtained when
the examples are repeated except that the catalyst
components, component proportions, comonomers, comonomer
proportions, and/or polymerizatlon conditions specified in
the examples are replaced with catalyst components, component
proportions, comonomers, comonomer proportions, and/or
polymerization conditions -taught to be their equiva~ents in
the specification.
While the present invention has been described
herein with refcrellce to p~rticul~r emodiments thereof, a
latitude o modiEication, various changes and substitutions
are intencled in the foregoing disclosure, and it will be
appreciated that in some instances some features of the
invention will be employed without a corresponding use of
other features without departing from the scope of the
lnvention as set forth.
!l
i
ii
' -54-
1!
