JPS5825323B2 - Silica supports, catalysts and methods - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the low pressure polymerization of ethylene alone or of ethylene and other alpha-olefins over a catalyst composition comprising a silica support.

Ethylene can be produced at low (<1000 psi) or high (>10
00 psi) pressure.

In order to make these catalysts useful for industrial purposes, it is currently necessary in each case to first dry the support to remove free water and then to dry the support before or after loading the transition metal compound. It was later found that it was necessary to activate the support at a temperature of the order of >300°C, preferably between 500 and 800°C, for at least 8 hours.

In some cases, this high temperature activation step must be carried out under certain restricted gas phase conditions.

Even when catalysts are produced under these stringent conditions, their effectiveness is limited from an industrial point of view because the reproducibility of the catalyst composition is difficult to control and the high temperature service conditions to which the activation equipment is subjected over long periods of time. This creates an additional disadvantage in that it tends to burn underneath.

U.S. Pat. No. 3,207,699 discloses the treatment of dried and calcined pickled silica alumina with trimethylsilane at elevated temperatures to provide improved acidic catalysts for various purposes. are doing.

However, silica, when treated in the manner described above, was not effective for the above purposes.

US Pat. No. 3,687,920 discloses simply adding various silane compounds to a supported chromocene compound.

In this method, the support (including silica) is thermally activated at elevated temperatures prior to incorporation of the chromocene compound or use of the silane compound.

The purpose of adding a silane compound to a catalyst used in the polymerization of ethylene is to improve the productivity of the catalyst.

US Pat. No. 3,879,368 discloses treating supported chromocene compounds with certain strong reducing agents and certain silane compounds.

In this process, the support (including silica) is thermally activated prior to the loading of the chromocene compound or the use of strong reducing agents or silane compounds.

The use of strong reducing agents and silane compounds allows the use of supports that are activated at relatively low temperatures.

The resulting composition is used as an ethylene polymerization catalyst and provides high yields of polymer with a relatively broad molecular weight distribution.

In this case, an industrially useful ethylene polymerization catalyst comprising a chromocene compound supported on a silica carrier can be obtained if the dry carrier is treated with a hydrosilane compound in the presence of a base before supporting the chromocene compound on the carrier. , carrier or supported chromium compound.

It has now been found that the process can be made at elevated temperatures without the need for thermal activation.

Such treatment provides a modified support to which the hydrosilane compound is chemically bound.

The object of the present invention is a novel ethylene polymerization or co-electrolysis method.

The object of the present invention is to provide a new and industrially useful silica carrier from which a catalyst for table use can be produced.

Another object of the present invention is to provide a new method for producing such a silica support.

Yet another object of the present invention is to provide a novel and industrially useful silica-supported ethylene polymerization catalyst prepared by a chromocene compound.

Another object of the present invention is to provide a novel method for producing an industrially useful catalyst for ethylene polymerization containing a novel chromocene compound supported on a silica carrier.

Another object of the present invention is to provide a new and industrially useful method for catalytically polymerizing ethylene using a novel catalyst comprising a chromocene compound supported on a novel silica carrier.

Yet another object of the present invention is to provide a novel catalyst for ethylene polymerization that is capable of producing ethylene polymers having relatively narrow melt flow ratios at a given melt index value.

It is an object of the present invention to provide a new catalyst for ethylene polymerization that has a relatively high response to hydrogen as a tart index modifier.

Yet another object of the present invention is to provide a novel catalyst for ethylene polymerization that allows relatively high yields of ethylene polymer to be obtained.

In this case, if a catalyst containing a chromocene compound supported on silica is used, before the chromocene compound is supported on a silica support, the support is treated with a certain hydrosilane compound in the presence of an unstable base such as the one described below. It has been found that the supported catalyst can be used industrially for the polymerization of ethylene without needing to be activated at a relatively high activation temperature.

Silica materials that can be used as supports in the catalyst compositions of the present invention have a high surface area, i.e., from about 50 to about 1000 m/g.
It is a porous material having a surface area in the range of 25 to about 200 microns and a particle size of about 25 to about 200 microns.

For use in fluidized bed reactor processes, the carrier particles are preferably rupturable.

This indicates that the carrier particles break down when used in a fluidized bed and in the presence of a growing polymer, and thus from one initial carrier particle to many with low polymer residue. This is the ability to cause the formation of particles.

Any grade of support can be used, but 350 m
Microspherical intermediate density (MS ID) silica (W.

R, Grace G-952 grade), 28.5 m
Intermediate density (ID) silica (W, R, Grade G-56 from Grace) having a pore size of 164/9 (7J) is preferred.

Other grades, such as 700rr? /g surface area and 50
G-968 silica (W, R,
Grace Inc.) is also completely satisfactory.

Variations in melt index control and polymer productivity can be expected between different grades of carrier.

When a chromocene compound is blended into a porous silica carrier with a high surface area as described above, it forms active sites on the surface and within the pores of the carrier.

The actual mechanism of lawlessness is not fully understood, but it can be thought of as follows.

That is, polymer begins to grow on the surface of the supported catalyst as well as within the pores.

When the polymer grown in the pores becomes large enough in the fluidized bed,
This ruptures the support and exposes new catalytic sites within the internal pores of the support.

Thus, the supported catalyst breaks down many times during its lifetime in the fluidized bed, thus enhancing the production of low catalyst residual polymer, thereby obviating the need to recover the catalyst from the polymer particles. It is.

If the support is too large, it will resist and prevent destruction, which will cause the catalyst to be discarded.

Additionally, large carriers may act as heat sinks and cause "hot spots" to form in the fluidized bed system.

For purposes of the present invention, the silica support is heated to about 100 to about 300° C., preferably about 150 to 250° C., for about 1 to 48 hours prior to treatment with the silane compound, which may result in surface adsorption. Sufficient to remove water, but insufficient to cause significant loss of silanol groups by condensation.

Silica can also be dried by azeotropic distillation of adsorbed surface water from the support.

This can be achieved by azeotropic distillation of a slurry of silica support in an azeotropic diluent.

The hydrosilane compound used in the present invention is silane (5
iH4) and the following structure Rn-(Si valve--H4-n (where R is an auto to C1o hydrocarbon group, and n is.

an integer from 1 to 3, preferably 1) This includes hydrocarbylsilane compounds having the following.

If the hydrocarbylsilane compound contains more than one R group, these R groups may be the same or different.

R groups are methyl, ethyl, etc. propyl, isopropyl,
Includes saturated and unsaturated aliphatic and aromatic groups such as butyl, isobutyl, amyl, decyl, phenyl and benzyl.

Preferred hydrocarbylsilane compounds include methylsilane, dimethylsilane, ethylsilane, diethylsilane, propylsilane, dipropylsilane, butylsilane, dibutylsilane, amylsilane and cyamylsilane.

Hydrosilane compounds can be used alone or in combination with each other to treat the carrier.

Treatment of the support with this hydrosilane compound is accomplished by contacting the hydrosilane with the support in the presence of a base.

This is conveniently carried out under atmospheric pressure and at a temperature of about 60-80°C.

Higher pressures and/or temperatures may also be used.

This contacting may be facilitated by dissolving the hydrosilane in its hydrocarbon solvent, then immersing the support in the solution, and then preferably adding a base.

Solvents for the hydrosilane tank include aliphatic and aromatic hydrocarbon solvents such as n-hexane, heptane, benzene and toluene.

Approximately 0 per mole of silanol groups on the surface of the silica support
．． 2 to 2.0 moles of hydrosilane are used, preferably about 0.4 to 0.8 moles.

Depending on the hydrosilane compound used, this corresponds to about 4-20% by weight of hydrosilane compound, based on the total weight of hydrosilane compound and silane carrier.

The bases used in the preparation of the novel supports of the invention are preferably unstable, ie basic substances having a boiling point of 150° C. at atmospheric pressure.

These materials have a pH of >7 in water or other suitable solvent.

The labile base is preferably a tertiary amine.

These amines include trimethylamine, diethylmethylamine, ethyldimethylamine, triethylamine, n
-Includes propyldiethylamine and the like.

Other basic compounds that may be used include alkali metal oxides, hydroxides and alcoholades.

However, these other basic compounds are more difficult to remove from the reaction system than the tertiary amines, which are volatile and soluble in organic solvents.

The basic compounds can be used alone or in combination with each other.

They are free of no-rogens. About 0.1 to 2.0 mol, preferably about 0.9 to 1.1 mol of base is used per mol of silane compound used.

When a support is treated with a hydrosilane compound in the presence of a base in accordance with the present invention, it is believed that the hydrosilane compound chemically binds to the support with simultaneous evolution of hydrogen gas, as shown in the equation below.

In addition, the chromocene compound has the following structure (where R' and R" are the same or different C1-C2
0 hydrocarbon group, n' and n'' are the same or different integers from 0 to 5)
known as a compound.

The R' and R'hydrocarbon groups may be saturated or unsaturated and include aliphatic, cycloaliphatic and aromatic groups such as methyl, ethyl, furoyl, butyl, pentyl, cyclopentyl, cyclohexyl, allyl, phenyl and hinabutyl groups. may include group groups.

Bis(cyclopentadienyl)chromium(II) compounds that can be used as catalysts supported on silica supports according to the present invention are disclosed in U.S. Pat.
No. 1,605.

The chromocene compounds may be used individually or in combination with each other.

The chromocene compound is preferably supported on a silica support from its solution.

This is preferably carried out by immersing the silica support in a solution of the chromocene compound and then evaporating the solvent under atmospheric or reduced pressure.

The chromocene compound is supported after the silica support is treated with a silane compound.

The chromocene compound is used in an amount such that the support carries about 0.1 to 3.0 weight percent chromium in the chromocene compound, based on the combined weight of the silica support and chromium metal.

After treating the support with hydrosilane and chromocene compounds, the resulting catalyst composition can be used directly for the polymerization of ethylene without further treatment, as described below.

This composite catalyst is in the form of powdered free-flowing solid particles.

The composite catalyst comprises, based on the total weight of its three essential components, about 80-96% by weight silica support, about 3.5-19.5% by weight hydrosilane compound, and about 0.5-10% by weight. It is produced from the chromocene compound of

Approximately 1×10 −6 to I per mole of monomer to be polymerized
X 10-'wt% composite catalyst is used.

The amount of catalyst used will vary depending on the type of polymerization method used.

Ethylene can be polymerized by the composite catalyst of the present invention alone or in combination with one or more other alpha-olefins.

The comonomer used together with ethylene in the monomer charge to be copolymerized according to the present invention is one or more alpha-olefins containing from 3 to about 12 carbon atoms. It's fine.

The monomer may also be a monoolefin or a non-conjugated diolefin.

These monoolefins used as comonomers,
Furopylene, 1-7"tene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-ethyl-1-butene, ■-heptene, ■-octene, ■- Decene, 4,4-dimethyl-1-pentene,
4.4-diethyl-1-hexene, 3.4-dimethyl-
Includes 1-hexene, 4-butyl-1-octene, 5-ethyl-1-decene, 3,3-dimethyl-1-butene, and the like.

Among the diolefins that can be used are 1,5-hexadiene, dicyclopentadiene, ethyrythenenorbornene, and the like.

Polymers made according to the teachings of the present invention have approximately 0.94
It is a solid material having a density of 5 to 0.970 and a melt index of about 0.1 to 100 or more.

A preferred polymer is a homopolymer of ethylene.

The copolymer contains at least 50% by weight, preferably at least 80% by weight of ethylene.

After the composite catalyst is formed, the polymerization reaction begins by contacting the monomer charge and a catalytic amount of the composite catalyst in the substantial absence of catalyst poisons at a temperature and pressure sufficient to initiate the polymerization reaction. It is done by letting

If desired, inert organic solvents can be used as diluents to facilitate material handling.

The polymerization reaction is highly dependent on the operating pressure, the pressure of the total monomer charge, the particular composite catalyst to be used and its concentration;
It is carried out at a humidity of from about 30°C or less to about 200°C or more.

The selected operating humidity also depends on the desired polymer melt index, since this is also a factor in controlling the molecular weight of the polymer.

Preferably, the temperature ranges from about 0°C to about 1°C in conventional slurry or "particle formation" processes carried out in inert organic solvents.
It is 00°C.

As with most catalyst systems, the use of high polymerization temperatures tends to produce polymers with low polymerization average molecular weights and therefore high melt indexes.

The pressure is sufficient to initiate polymerization of the monomer charge and from subatmospheric pressure (when using an inert gas as a diluent) to about 1.000,000 ps
Pressures can be above atmospheric pressure up to ig or more, but preferred pressures are about 1000 p.p.
It's sigl.

As a general rule, a pressure of 20 to 800° is preferred.

81g Where an inert organic solvent is used in the method of the invention.

If so, it should be inert towards all other components and products of the reaction system and stable under the reaction conditions used.

However, it is not necessary for the inert organic solvent to also be the solvent for the resulting polymer.

Inert organic solvents that can be used are aliphatic hydrocarbons such as hexane, heptane, benitane, isopentane, isooctyne, purified kerosene, etc.; saturated cycloaliphatic carbonates such as cyclohexane, cyclopentane, dimethylcyclopentane, methylcyclohexane, etc. hydrogen; benzene;
Aromatic hydrocarbons such as toluene, xylene, etc.; chlorinated hydrocarbons such as chlorobenzene, tetrachloroethylene, o-dichlorobenzene, etc.

Particularly preferred are hydrocyclohexane, pentane, isopentane, hexane and heptane.

If it is preferred to carry out the polymerization at such high solids contents, it is of course desirable that the solvent is liquid at the reaction temperature.

For example, when carried out at temperatures below the solution temperature of the polymer in a solvent, the nature is to form a slurry or suspension in which the polymer actually precipitates from the liquid reaction medium and the catalyst is suspended in finely divided form. It can be a polymerization method.

This slurry system will, of course, depend on the particular solvent used in the polymerization as well as its humidity for the polymer being produced.

Therefore, in the "particle formation" process, it is most desirable to operate at a temperature below the normal solution temperature of the polymer in the chosen solvent.

For example, the polyethylene produced by the process may have a heating temperature of about 90°C in cyclohexane, whereas its solution temperature in pentane will be about 110°C.

It is in this single particle formation system that high polymer solids contents are possible even at low temperatures, provided that sufficient agitation is provided to achieve proper mixing of the monomer and the material undergoing polymerization. It is a characteristic of

Although its polymerization rate may be slightly slower at lower temperatures,
It is believed that the monomers are more soluble in the solvent and thus act to eliminate the tendency for low polymerization rates and/or low polymer yields.

The monomer also appears to have significant solubility properties even in the solid portion of the slurry, since a wide range of solid particles can be provided in the slurry, as long as adequate agitation is provided and the polymerization temperature is maintained. This is also a feature of the slurry method.

Experience has shown that slurry technology can produce systems with solids content greater than 50% if sufficient agitation conditions are maintained.

It is particularly preferred to carry out the slurry process at a polymer solids content of 30 to 40% by weight.

In this embodiment, recovery of the polymer from the solvent is reduced to a simple force filtration and/or drying operation, and no effort is required for cleaning the polymer or separating or purifying the catalyst.

The residual concentration of catalyst in the polymer is so small that it can remain in the polymer.

If the solvent serves as the primary reaction medium, it will, of course, be necessary to redistill or otherwise purify the solvent prior to use in the process, thereby rendering the solvent medium substantially anhydrous and free of possible contaminants such as moisture and oxygen. It is desirable to keep the catalyst poison free.

Treatment with adsorbent materials such as high surface area silica, alumina, molecular sieves, and similar materials can be beneficial during the polymerization reaction to remove trace contaminants that may slow the polymerization rate or poison the catalyst. be.

The molecular weight of the polymer can also be further adjusted by carrying out the polymerization reaction in the presence of hydrogen, which is believed to function as a chain transfer agent.

Experience has shown that hydrogen may be used in the polymerization reaction in amounts between about 0.001 and about 10 moles of hydrogen per mole of olefin monomer.

However, for small polymerization reactions, the full molecular weight range can be obtained by using from about 0.001 to about 0.5 moles of hydrogen per mole of monomer.

The homopolymerization or copolymerization of ethylene using the catalyst of the present invention can also be achieved by a fluidized bed reaction method.

An example of a fluidized bed reactor and method that can be used for this purpose is disclosed in British Patent No. 1.253.063.

The following examples are merely illustrative of the invention and are not intended to limit its scope.

Examples 1-8 A series of eight catalysts were prepared with and without various silane compounds to demonstrate their effectiveness in accordance with the teachings of the present invention.

For comparison purposes, the catalyst of Example 1 was prepared without any silane or amine compounds.

The support used for each catalyst was medium grade silica with a surface area of 300 m/g and an average particle size of 200 people.

The support was first heat treated at 200°C for 18 hours under nitrogen.

The support heated in this way contained 25 mmol of silanol groups per gram.

Then 8 g of this silica (20 mmol 5iOH)
was slurried in about 100 ml of n-hexane and then about 1.4 p (16 mmol) of butylsilane was added.

The silane compound was used in an amount to provide 0.8 moles of silane compound per mole of silanol groups on the silica support.

Similarly, other hydrosilane compounds of the invention may be used in amounts to provide about 0.2 to 2.0 moles of silane per mole of silanol groups on the silica.

The slurry was then heated to a reflux temperature of about 75°C and then 1.9 g (20 mmol) of triethylamine was slowly added to the reflux system over about 1 hour.

When used, the amine is between 0.1 and 1.0 (C
2H5) was used at a 3N/5iOH ratio.

The system was then refluxed overnight (~18 hours).

Chemical bonding of the silane compound to the support and concomitant evolution of hydrogen appears to have occurred during this treatment.

The system was then cooled and the silica was washed in n-hexane and dried under vacuum at 80°C.

All tests were conducted under conditions that did not contain water.

The silane compounds used for each phase are shown in Table I below, along with the ratio of silane compounds to silanol groups.

0.4 g, 0.8 g or 1.0 g of the support prepared above is then teslarized in about 1001 rLl of n-hexane, and then 20Tn9 of bis(cyclopentadienyl)chromium is added to this slurry. A supported catalyst was prepared by the following method.

This slurry was stirred for about 30 minutes to cause the chromium compound to be supported on the carrier.

The amount of support used for each catalyst is also shown in Table I.

Using each of the eight catalyst systems prepared as described above, ethylene was heated at 60-70° in 500 ml of n-hexane.
C was homopolymerized under H2 pressure of 125 psi and ethylene pressure of 175 psi.

Each reaction was run for approximately 30 minutes.

The yield of polymer produced in each experiment is also shown in Table 1.

The resulting polymer in each case had a solid high density (〉0.95
) was a substance.

Inspection of this data indicates that active catalysts are obtained only when the catalyst support is modified with the hydrosilane compounds of the present invention (Examples 2-8).

Preferred hydrosilane compounds (Examples 2-3) provide supported catalysts that give relatively high yields of polymer.

Examples 9-12 A series of four supported catalysts were prepared using silica-alumina supports to demonstrate the ineffectiveness of the present invention.

For comparison, the catalysts of Examples 9-10 were prepared without any silane or amine compounds.

The support was silica-alumina containing about 87% silica and about 13% alumina by weight.

This support had a surface area of approximately 475 rrt/g.

The support was heat treated under nitrogen for 18 hours. Thus, the carrier of Example 9 was treated at 600°C, whereas the carriers of Examples 10-12 were treated at 200°C.

The supports of Examples 11-12 were then treated with butylsilane and l-ethylamine as described in Examples 1-8, and 1.0.

Silane/〉S i OH ratio and 1,0 (C2H5)
N/'') SiOH ratio was used.

Table 1 below lists the activation temperature of the support as well as the silane compound used on each side.

Next, supported catalysts were prepared as in Examples 1-8 using 0.4 g or 0.8 g of support.

The amount of support used for each catalyst is also shown in Table 3.

Ethylene was homopolymerized as in Examples 1-8 using each of the four catalyst systems prepared as described above.

The yield of polymer produced in each experiment is also listed in Table ■.

The polymer produced in Example 9 was a solid, high density (>0.95) material.

The data in Table 1 indicate that silica-alumina supports are not effective in the present invention and must be thermally activated at a relatively high degree of activation to produce satisfactory results.

Examples 13-14 The ethylene polymerization catalyst of the present invention was compared to a catalyst prepared as disclosed in British Patent No. 1.253,063.

This prior art catalyst was prepared by loading 4% by weight of chromocene on a silica support that was thermally activated at 750° C. for 8 hours under nitrogen.

This support had a surface area of 300 m/, 9 and an average particle size of 200^.

The chromocene compound was added to the carrier as described in Examples 1-8.

Catalysts of the invention were prepared as in Examples 1-8 using the same supports as above, butylsilane, triethylamine and chromocene.

This support was also made using 4% by weight chromocene.

The support was dried at 250° C. for 18 hours under nitrogen.

Each catalyst was then used to homopolymerize ethylene in a fluidized bed reactor of the type described in GB 1.253.063.

The reaction was carried out at 100°C, 1300 psi ethylene pressure and 4
A space-time yield of ~5 was performed.

The reaction was continued for about 200 hours.

Hydrogen was used as a molecular weight regulator.

The average results obtained regarding the properties of the polymers produced are shown in Table 1 below.

Polymer was produced at a rate of approximately 30-40 Ab/hour.

Table ■ also lists the salient features of the two catalysts.

The test results listed in Table 1 show that the catalyst of the present invention made with a support heat treated at 250°C and further treated with butylsilane is substantially equivalent in performance to the prior art catalyst heat treated at 750'C. It is shown that.

(9) In addition to the chromocene compounds shown above, other transition metal compounds that can be supported and used as catalysts on the silica carrier of the present invention include:
U.S. Patent Application No. 6 filed December 29, 1975
44,814, including fused bis(indenyl)- and hibis(fluorenyl)-chromium (ID compounds).

The disclosure of this patent application is incorporated herein by reference.

These supported fused ring compounds are about 0.001 to 25% by weight based on the total weight of the fused ring compounds and the silica support.
or more.

These fused ring compounds can be supported on the silica carrier of the present invention in the same manner as the lomocene compound as described above.

The supported fused ring compound can be used as a catalyst for ethylene polymerization.

These fused ring organochromium compounds have the following structure Ar
Cr1I Ar' [here, Ar and Ar' are the same or different, and have the following structure (here, Ra is the same or different 01~C1° hydrocarbon group, m is 0~ is an integer of 4, and X is 0, 1, 2
or 3) and an indenyl group and a truncated structure (where Rb is the same or different 01-C1° hydrocarbon group, and m' and m' are the same or different integers of 0-4) Z is H or Rb, and Z is 0 or 1).

The Ra and Rb hydrocarbon groups may be saturated or unsaturated and they include aliphatic, cycloaliphatic and aromatic groups such as methyl, ethyl, propyl, methyl, pentyl, cyclopentyl, cyclohexyl, allyl, phenyl and hinamethyl groups. may include group groups.

Fused ring compounds that can be used on silica supports according to the invention include:
J., M., Birmingham, F.G.
A, 5tone, R, West [Ad
vance inOrganometallic Ch
emistry J p, 377-380 (Acade
mic Press, published in 1964).

This document is included as a reference.

Claims (1)

Claims: 1. Dry at a temperature of about 100-300°C and in the presence of a base silane or the following structure (where R is a hydrocarbon radical containing 1-10 carbon atoms) A catalyst composition for olefin polymerization, comprising a chromocene compound supported on a silica carrier treated with a hydrosilane compound, wherein n is an integer of 1 to 3. 2 The hydrosilane-treated support is coated with a chromocene compound to give about 0.5
to carry ~10% by weight of the chromocene compound,
A catalyst composition according to claim 1 which has been treated.