The method of preparation of a carrier for catalysts, catalyst for polymerization of olefins and method for polymerization of olefins by using a catalyst

 

(57) Abstract:

The method of preparation of a carrier containing silicon dioxide and at least one component selected from aluminum oxide and aluminum phosphate, which is mixed alcohol, water, an alcoholate of silicon and acid under such conditions, in order to avoid gelation or precipitation of silicon dioxide; add to the mixture acidic solution of aluminum compounds and/or solution of a source of phosphate ions; then add a gelling agent, collecting the gel and subjected to washing with water and then the organic liquid, and then dried gel pulverization to obtain a powder and calcined powder. Polymerization of olefins in the presence of a catalyst containing chromium on the media specified above. 3 S. and 7 C.p. f-crystals, 1 Il., table 2.

The invention relates to a method of manufacturing a carrier for catalysts containing silica and at least one component selected from aluminum oxide and aluminum phosphate. It applies, moreover, to catalysts for the polymerization of olefins containing chromium in the medium, and to the use of these catalysts for the polymerization of olefins.

The carriers formed by mixtures of oxides, ispolzoyovanija media containing aluminum oxide and aluminum phosphate, which carry out the reaction of the alcoholate of aluminum with an aqueous solution containing phosphate ions, produce media and calcined.

In the patent application EP-A-283815 disclose a method of preparation of a composition containing alumina as a predominant component and silica, which comprises the following stages:

(a) mixing a quantity of an aqueous solution (I) salt of aluminum with a certain amount of an aqueous solution (II) aluminate of an alkali metal to obtain a suspension of hydrogel of aluminum oxide, deposited at a pH of from 8 to 10;

(b) it added an additional amount of solution (I) to achieve a pH of from 2 to 4;

(c) the mixture was added an additional amount of solution (II) to achieve a pH from 8 to 10;

(d) repeating at least once steps (b) and (c);

(e) the mixture was added an aqueous solution of alkali metal silicate to obtain a suspension of hydrogel of aluminum oxide - silicon dioxide;

(f) separating the hydrogel from the suspension;

(g) dehydrating thus obtained hydrogel by heating.

The method may further include stage and especially the stage of impregnation of the composition obtained is as a patent in the UK-A-2 090 158 describe the method of preparation of a carrier for catalysts, containing compounds of silicon dioxide and aluminum phosphate, which prepare a solution containing isopropanol, water, phosphoric acid, ethylate silicon and sulfuric acid, the mixture was added aluminum nitrate, phosphoroamidite acid and chromium nitrate, and then injected ammonium hydroxide to implement co-gelation.

This well-known carrier has a high degree of heterogeneity and crystallizes very quickly from the moment when it is subjected to annealing at temperatures above 700oC. on the other hand, this media is not simultaneously combines high specific surface area with a high pore volume. From this it follows that this well-known carrier does not allow to produce chromium catalysts for the polymerization of olefins, which have simultaneously increased catalytic activity, a small induction period of the polymerization and a good sensitivity to hydrogen. In addition, it is not possible to obtain polyolefins having a modulated distribution of molecular weights between srednechirchik distribution and a very wide distribution for this indicator fluidity, and he usually gives rise to a significant formation of oligomers.

Isolatorweg structure, resistant to crystallization, which has simultaneously increased pore volume and high specific surface area and which when used as a carrier for a catalyst based on chromium in the polymerization of olefins provides this catalyst combination of the following advantages:

- increased catalytic activity even in the absence of joint catalyst

a small induction period of the polymerization, even negligible,

good sensitivity to hydrogen, the catalyst allows to obtain polyolefins having:

- modulated distribution of molecular weights between srednechirchik distribution and a very wide distribution for this indicator fluidity and

a small fraction of oligomers.

In accordance with this invention relates to a method for preparing a carrier for catalysts containing silica and at least one component selected from aluminum oxide and aluminum phosphate, which is mixed in the first stage, alcohol, water, an alcoholate of silicon and acid in such quantities that the molar ratio of water and silicon was from 2 to 50; the first stage is carried out at acidic pH by mixing water, acid, alcoholate is evanie received hydrolytic environment at a temperature at least equal to the 20oC and below the boiling point of the medium, and at least part of alkoxygroup alcoholate of silicon substituted by hydroxy groups, without gelation or precipitation of silicon dioxide; in the second stage in the received gidrolizny medium was added acidic solution of aluminum compounds and/or solution of the phosphate ion source and the third stage of the gelation agent to obtain the precursor gel, then washed precursor gel with water and then the organic liquid, collecting the suspension of the gel in the organic liquid, and then subjecting the suspension is dried to obtain a powder and calcined powder; according to the invention the drying is performed by spraying.

In the method according to the invention used in the first stage, an alcoholate of silicon can be any compound in which silicon is associated with at least one group of alkoxyl, such as aromatic or aliphatic, linear, branched or cyclic chain, saturated or unsaturated, unsubstituted or substituted alkoxygroup. Group alkoxyl usually contain from 1 to 20 carbon atoms. The alcoholate of silicon covering alkoxyl aliphatic types, especially recommended; prefer the methyl alcoholate, ethyl n-propyl, ISO-propyl, n-butyl and ISO-butyl. The alcoholate of silicon, which are particularly suitable are tetraethyl, tetramethrin, tetraisopropyl silicon. Especially preferred Tetra-ethylate silicon. Of course, you can apply multiple alcoholate of silicon in the first stage of the method according to the invention.

In the method according to the invention, the alcohol used in the first stage for the dissolution of silicon alcoholate. In principle, can fit any alcohol, which dissolves the silicon alcoholate and which can be mixed with water. Thus, it is possible to use alcohol, a hydrocarbon group which may be saturated, unsaturated, aromatic or aliphatic, linear or cyclic, unsubstituted or partly or completely replaced. Preferred aliphatic alcohols with a linear chain. As examples, ethanol, isopropanol and methanol. Especially preferred is ethanol. Needless to say, that can be used multiple spirits in the first stage of the method according to the invention. Used mainly alcohol, a hydrocarbon group which corresponds to a group of alkoxyl used alcoholate of silicon.

The amount of alcohol used in pervisit of selectable silicon alcoholate and alcohol, from the solubility of the silicon alcoholate in alcohol and the temperature at which carry out the first stage. In practice, it is unprofitable to use the number, greatly exceeding the required minimum number, since a large excess causes unnecessary dilution of the mixture leaving the first stage, which should be avoided.

The first stage of the method according to the invention has the purpose of (a) partial hydrolysis of the alcoholate of silicon in the presence of water and (b) a partial condensation of the hydrolyzed silicon alcoholate, according to the following reactions:

(a) Si(O-R)4+x H2O ---> Si(OH)x(O-R)4-x+x R-OH

(b) 2Si(OH)x(O-R)4-x---> O-[Si(OH)x-1(O-R)4-x]2+H2O

or

2Si(OH)x(O-R)4-x---> [Si(OH)x(O-R)3-x]-O-[Si(OH)x-1(O-R)4-x]+R-OH,

in which R represents a hydrocarbon radical, which may be aromatic or aliphatic, saturated or unsaturated, linear, branched or cyclic, which can, if necessary, be different among the four groups (O-R), and x represents the number above 0 and below 4, mainly from 0.1 to 3.9. In the first stage, use this amount of water so that the molar ratio between the amount of water and to the possessing from 2 to 20, especially from 8 to 12, for example, about 10.

In this text mean by "hydrolyzed and condensed alcoholate of silicon compounds:

O-[Si(OH)x-1(O-R)4-x]2and

[Si(OH)x(O-R)3-x]-O-[Si(OH)x-1(O-R)4-x] defined above.

The main feature of the method according to the invention is the combination of such working conditions at the first stage of hydrolysis, which avoid any precipitation or gelation of the silica in the environment, hydrolysis. To this end, the mixing in the first stage is carried out in certain conditions regarding pH and temperature of the hydrolysis medium, the molar ratio of the applied amounts of water and alcoholate of silicon and method of mixing the reagents. Under hydrolytic environment means the environment obtained after mixing water, acid, silicon alcoholate and alcohol. To this end, the first stage of the method according to the invention the pH of the hydrolysis medium has an acidic value. Usually pH below 3, preferably from 0.5 to 2.5, for example, approximately equal to 1. The acid used in the first stage, may be mineral or organic. It is advantageous to choose from acids, mixed with water, in which the anion can easily adalats the priori or sulfuric acid. Mostly use hydrochloric acid or nitric acid. Particularly well suited hydrochloric acid. If necessary, you can apply several acid in the first stage of the method according to the invention. The amount of acid should be sufficient to maintain the pH of the acid throughout the duration of the first stage. The amount of acid depends at this time, the degree of acidity of the used acid and other reagents from the temperature at which carry out the first stage. Disadvantageous to use a too high amount of acid in order to avoid the need for removal at a later stage of processing of the precursor gel, excess acid or its derivatives.

In the first stage of the method according to the invention is important mixing of the reagents in a controlled manner to avoid precipitation or gelation of the silica and to avoid heating the mixture. To this end, the reagents can be mixed by any known appropriate method, if the temperature during mixing of the reactants equal to the maximum 30oC and if no precipitation or gelation of the silica. Mostly stirring is carried out by adding the got. This can be done by the adulteration of the preliminary mixture of water and acid to the pre-mixture of alcohol and alcoholate of silicon. Another way is to adulteration of the preliminary mixture and alcoholate of silicon to the pre-mixture of water and acid. Get good results by adding one of the pre-mixes drop by drop into another pre-mix, supported with stirring. Particularly satisfactory results are obtained by adding a pre-mixture of water and acid drop by drop and under stirring to a preliminary mixture of alcohol and alcoholate of silicon.

In the first stage of the method according to the invention maintain the temperature during mixing of the reactants below the 30oC, mostly below the 20oC, usually around 10oC, the recommended temperature is above 0oC; then hydrolysis medium is subjected to maturation at a temperature at least equal to the 20oC and below the boiling temperature environment, for example, from 30 to 100oC, more than the normal temperature from 40 to 80oC, the recommended temperature from 50 to 70oC. Mainly maturation hydrolysis medium is carried out at a temperature above the mixing of chemicals.

On PE is and silicon reactions, defined above. All other parameters remain the same, the degree of hydrolysis of the alcoholate is higher (the number "x" is the greater), the longer the duration of puberty. Since then, the duration of ripening should be sufficient to have a similar hydrolysis reaction, which is described above; however, it should be less than the time required for gelation or precipitation of silicon dioxide. The optimal duration of ripening depends on the pH of the hydrolysis medium, the nature of the reagents present in the hydrolysis medium, and the temperature and can vary from several minutes to several tens hours. Usually lasting less than 24 hours duration is Mainly from 0.5 to 3 hours

In a particularly advantageous embodiment of the method according to the invention is used, in addition, in the first stage, the titanium alcoholate. The alcoholate of titanium may be present, for example, a compound in which the titanium is associated at least with a group of alkoxyl as aromatic or aliphatic, linear, branched or cyclic, saturated or unsaturated, unsubstituted or substituted alkoxygroup. Group alkoxyl include typically from 1 to 20 carbon atoms. Alcoh. Azumaya, you can apply multiple alcoholate of titanium on the first stage of the method according to the invention. The alcoholate of titanium, if necessary, can be applied in the form of a solution in a liquid hydrocarbon. Good spirits.

The quantity of alcoholate of titanium, used in this embodiment, typically such that the titanium is present in the precursor gel in proportions varying from 0.05 to 20 wt.%, mainly from 0.1 to 15 wt.%, especially from 0.5 to 10 wt.% titanium based on the total weight of the solid fraction of the precursor gel.

In this embodiment, the titanium alcoholate can be applied at any time in the first stage. The alcoholate of titanium, for example, to add to the pre-mixture containing water and acid, or pre-mixtures containing silicon alcoholate and alcohol. Alternatively, the titanium alcoholate can be added to the hydrolysis medium obtained after mixing water, acid, silicon alcoholate and alcohol, before puberty, during puberty or after puberty. Good results are obtained when the titanium alcoholate add during maturation. Recommended to add the titanium alcoholate after the first part of maturation, which is mainly oenia alcoholate of titanium.

This implementation is particularly advantageous when you want to include the titanium in the precursor gel in increased quantity that can reach 20 wt.% the total weight of the solid fraction of the precursor gel, avoiding in the subsequent stage of agglomerates of crystalline titanium dioxide in the form of anatase or rutile".

The connection of the aluminum used in the second stage of the method according to the invention may be any compound of aluminum, which is soluble in the acid solution used in the second stage, and which is capable of gelation under the action of the gelling agent. Especially recommended inorganic salts of aluminum and aluminum alcoholate. From aluminum alcoholate used are usually those in which the aluminum associated with at least one group of alkoxyl. Among the aluminum alcoholate is especially recommended such that contain aliphatic group; prefer the aluminum alcoholate containing aliphatic unsaturated straight unsubstituted groups such as, for example, the group of methyl, ethyl, n-propyl, ISO-propyl, n-butyl and ISO-butyl. Mainly use aluminum alcoholate, alkoxygroup which contain from 1 to 20 atoms pirogrupp used alcoholate of silicon.

Satisfactory results are obtained with inorganic salts of aluminum. Among the inorganic salts of aluminum are particularly preferred aluminum nitrate and aluminum chloride.

In a special embodiment of the method according to the invention, in which use the alcoholate of aluminum as aluminum compounds, the latter are used at least partially in the first stage of the method according to the invention mainly in case of need in the preliminary mixture of alcohol and alcoholate of silicon. The alcoholate of aluminum can also be added to the output from the first stage after puberty.

In the method according to the invention the ion source indicates the compound soluble in the solution used in the second stage, and capable of forming therein phosphate ions. Especially recommended inorganic salt of phosphate /for example, monopotassium phosphate calcium formula CaH4(PO4)2secondary acid phosphate of the formula Na2HPO4and tricalcium phosphate of the formula Ca3(PO4)2/, epirizole phosphoric acid /for example, ethylphosphate formula (C2H5)3PO4/ and phosphoric acid. Mostly use phosphoric acid.

The acidic solution compounds rigorously any appropriate known method, and they mostly are mixed with the mixture obtained in the first stage of the method according to the invention.

In an advantageous embodiment of the method according to the invention, the source of phosphate ions added previously to the acid solution of the aluminium compound to the second stage of the method according to the invention only one solution, acidic, containing both a compound of aluminum and a source of phosphate ions.

In the first variant of this form of implementation of the method according to the invention, where the acidic solution contains only the connection of aluminum and contains no phosphate ion source, an acidic solution is usually obtained by dissolution of aluminum compounds in water and/or alcohol, sufficient to ensure complete dissolution, adding to the acid solution in a quantity sufficient to prevent the formation of aluminium hydroxide, which immediately precipitates from this moment does not participate more in the education of the precursor gel. To dissolve the aluminum compounds used amount of solvent (water or alcohol), which exceeds the required minimum, as any excess solvent associated with removal during subsequent processing and drying of the gel.

The use of the second variant of this form of implementation of the method according to the invention, where the acidic solution contains only the source of phosphate ions and does not contain aluminum compounds, acidic solution is usually obtained by dissolving a source of phosphate ions in water and/or alcohol, sufficient and mostly without excessive for the groups mentioned above. In this second embodiment, the source of phosphate ions gives the acidic nature of the solution, so no need to add more acid and the solution.

In the third variant of this formula, the method according to the invention, which is preferred, the solution contains a compound of aluminum and a source of phosphate ions and the acidic solution obtained by dissolution of the aluminium compound and the phosphate ion source in any order in sufficient amount of water and/or alcohol, but without excessive for the groups mentioned above. In this preferred embodiment can also be useless adding to the acid solution, provided that the source of phosphate ions gives the solution a sufficient acidity to avoid the formation of aluminium hydroxide.

Needless to say that you can apply in the second stage, several compounds of aluminum and/or multiple ion sources of phosphates.oC, usually lower than or equal to 20oC, for example, between 0 and 10oC during the whole time of the additive. Gelling agent used in the third stage of the method according to the invention is any compound capable of causing a co-gelation of the reagents used for the first and second stage (condensed and hydrolyzed silicon alcoholate, coming from the first stage and defined above, a compound of aluminum and/or source of phosphate ions and, if necessary, the titanium alcoholate) in the form of a mixed oxide of silicon and aluminum and/or phosphorus and, if necessary, titanium. As an example, a gelling agent can be called oxide SS="ptx2">

The amount of gelling agent used in the third stage, mostly sufficient for providing full gelation hydrolyzed and condensed silicon alcoholate, defined above, aluminum compounds and phosphate compounds present in the environment co-gelation. Under the environment co-gelation mean reaction mixture in the course of gelation in the third stage of the way. Environment co-gelation now includes the environment, the resulting output of the second stage of the method according to the invention (containing a hydrolyzed and condensed alcoholate of silicon, a compound of aluminum and/or source of phosphate ions) and a gelling agent. The number used gelling agent mostly sufficient for providing full co-gelation of the total weight of hydrolyzed and condensed alcoholate of silicon, aluminum compounds and a source of phosphate ions; mostly it is a little bit higher a sufficient amount of.

At the third stage of the method according to the invention the pH of the medium of gelation is usually higher than or equal to 5, usually greater than or equal to 6; pH is usually below 11; recommended values below 10. Mainly modelchina pH can be provided by any appropriate known method, for example, using a buffer solution, the relatively inert to the reagents in the process of gelation, or using the installation, allowing for continuous or periodic supply connection, changing the pH in the environment co-gelation. Mostly use a vessel containing a gelling agent, which is injected separately and in a controlled way mixture leaving the second stage, and the connection controller pH. As the connection of the pH Adjuster can be used any compound, acidic or basic, relatively inert reagents during gelation.

In the third stage of the method according to the invention may be advantageous, depending on the properties of the gel precursor, which wish to receive, thermostatically environment co-gelation to a temperature below or equal to 30oC, mainly to a temperature of from 0 to 20oC.

In a particularly advantageous first embodiment of the method according to the invention it is possible to introduce, in addition, the gel precursor is a transition metal selected among the elements of groups IVB and VB of the Periodic table of elements, such as zirconium and vanadium, or an element of group IIIA of the Periodic table of elements, excellent o these elements to the mixture, received on the first or on the second stage of the method according to the invention, before carrying out the next stage. If necessary, you can add salt or alcoholate to the pre-mixture of water and acid or prior to the mixture of alcohol and alcoholate of silicon used in the first stage of the method according to the invention.

In the second embodiment of the method according to the invention, which is preferred, is subjected to gel coming out of the third stage of maturation. Last performed in the environment of maturation, which may be the environment co-gelation collected from the third stage, if necessary, with stirring. It is possible to add an inert compound that alters the pH of the medium maturing, such as the primary connection. Alternatively, the gel is first separated from the environment co-gelation, for example, by centrifugation and then suspended in an inert liquid, such as water or alcohol, to carry out ripening. This option has the advantage that it removes part of the ionic impurities adsorbed in the gel resulting from the reagents used in the manufacture of the gel.

Maturation is aimed at the extension of the co-gelation and change thus the specific surface and the boiling point of the medium maturing. Work mainly at approximately the 20oC. Time of ripening depends on the temperature and properties (specific surface area and pore volume) of carrier. It may change in this case from several minutes to several tens hours. The best results are obtained over time at least one hour. Taking into account economic considerations, it is unprofitable to extend the maturity above 48 hours

Maturation is usually carried out at a pH value above or equal to 6, mostly from 8 to 10.

At the output of the third stage of the method according to the invention and, if needed, after maturation, collect the gel precursor, which is then subjected to washing, first with water and then the organic liquid.

Water rinse is usually suspendirovanie gel in water, taken in an amount sufficient to remove a portion of at least contained in the gel impurities, and then removes a portion of at least this amount of water to any appropriate known methods, for example by centrifugation or filtration, mainly by centrifugation, given the rapidity of this method. Of course, you can repeat the washing with water several times. The temperature at katorse in a wide limit. Work mainly at room temperature.

Then subjected to water-washed gel washing with an organic liquid, for example, spraying the gel in this organic liquid at room temperature. Washing of the organic liquid to remove part at least of the water which has soaked into the gel. The selected organic liquid should be at least partially miscible with water, inert relative to the gel, however, is able to moisten the gel. She has preferably the evaporation temperature below 120oC, usually below 100oC, for example from 70 to 90oC. the Organic liquid used in the washing, are alcohols, ethers, and mixtures thereof. Prefer alcohols, particularly those containing from 1 to 4 carbon atoms. Good isopropanol. Of course, you can repeat several times the leaching of organic liquid and apply several organic liquids. At the exit of the washing, it is desirable to separate the gel at least part of the water and used organic liquid by centrifugation or filtration.

In the method according to the invention are collected after washing the organic liquid suspension of the gel in the organic is continued to obtain a powder carrier in the state of mist.

The atomization can be accomplished, for example, spraying a suspension of the gel through the hole of small size. It is usually carried out in the gas flow, relatively inert gel. The gas stream mainly contains no oxygen. Suitable gas stream, containing mainly nitrogen. The temperature of the gas stream is often above 100oC. Recommend, for example, temperatures from 150 to 450oC (mostly from 200 to 400oC, for example about 300oC) at the entrance to atomization hole and from 20 to 200oC (mostly from 50 to 150oC) at the end of the atomization. You can work indifferently at pressures below, equal to or above atmospheric pressure. Prefer pressure above or equal to the atmospheric pressure, is especially recommended pressure 1 to 10 bar. The suspension of the gel can be entered at room temperature (between 15 and 25oC) in the gas sprayed particles are usually at the same temperature as the gas in the end atomization.

Often at the exit of the drying to produce a powder having a moisture content below 1 wt. %, mostly below 0.5. %, for example less than 0.2 wt. %.

The spray drying is the OS the oil thus so they were suitable for use as carriers of catalysts for the polymerization of olefins. In fact, the sprayed particles are distinguished, on the one hand, a narrow size distribution and, on the other hand, a narrow distribution of pore radii and small, even negligible content of macropores with a radius higher than 2000 , while maintaining an increased pore volume.

At the outlet of the spray drying collect the powder carrier, which if necessary can pass through a sieve to separate particles of undesired size. This powder is subjected to calcination. The calcination is designed to remove at elevated temperatures of organic impurities from the powder. It usually lasts until the weight of the powder over time does not remain constant, without crystallization of the powder. The calcination can be performed in an atmosphere of air (mainly in the atmosphere of dry air) in the fluidized bed at a temperature below the crystallization temperature of the powder. The temperature is generally from 300 to 1500oC, typically from 350 to 1000oC, mainly from 400 to 600oC.

The method according to the invention allows to prepare carriers for catalysts containing mixed oxides of CT to go to triple the chart between the composition of silicon dioxide, aluminum oxide and aluminum phosphate. The accompanying drawing represents this phase diagram. The method according to the invention proves to be particularly successful for the manufacture of carriers, which is located in the shaded part of the specified three-phase diagram. The method according to the invention allows also to include in the media transition metal or an element such as boron. The method according to the invention allows to prepare carriers for catalysts in the amorphous state, which represent a very homogeneous dispersion of the components and which have at the same time this specific surface, such pore volume and such resistance to crystallization, which make them effective in the polymerization of olefins.

Taking into consideration the physical and structural characteristics of the carrier obtained by the method according to the invention, it finds a particularly interesting application as a carrier for catalysts for the polymerization of olefins, mainly containing chromium oxide.

The media made by the method according to the invention, is particularly effective, as they allow to obtain catalysts for the production of polyolefins, in which the flow index may vary within wide limits.

The invention also relates to a catalyst for polymerization of olefins containing chromium on a carrier obtained by means of the method according to the invention, which is defined above.

The catalyst according to the invention can be obtained in a known manner by soaking the powdered media aqueous or organic solution of a compound of chromium, followed by drying in an oxidizing atmosphere. With this purpose you can use the chromium compound selected among soluble salts, as oxide, acetate, chloride, sulfate, chromate and bichromate in an aqueous solution or as acetylacetonate in organic solution. After impregnation of the carrier with the chromium compound impregnated carrier is usually activated by heating it at a temperature of from 400 to 1000oC to convert at least part of the chromium in the hexavalent chromium.

The catalyst according to the invention can also be obtained by mechanical mixing a powdery medium with a solid chromium compound, for example, with chromium acetylacetonate. Then this mixture can be activated at temperatures below tempt, chrome compounds can also be included in the powdered carrier during manufacture of the latter or at the time of manufacture of the precursor gel of the media. To this end, for example, to add his part or in full, in an acidic solution of aluminum compounds and/or source of phosphate ions used in the second stage of the method of manufacturing according to the invention the precursor gel, co-precipitation of chromium oxide simultaneously with the oxide of silicon, aluminum and/or phosphorus. You can also add the chromium compound to the precursor gel before puberty or after puberty last.

In the catalyst according to the invention, chromium is usually present in an amount which varies from 0.15 to 10 wt. %, mainly from 0.1 to 5 wt. %, especially from 0.25 to 2 wt. % chromium relative to the total weight of the catalyst.

The catalyst according to the invention is particularly effective in the polymerization of olefins. In fact, for this application, the catalyst according to the invention has a number of advantages:

- increased catalytic activity, even in the absence of co-catalyst;

a small induction period of the polymerization, is almost completely missing;

good chuvstvitelnye molecular weights from medium-wide to very wide for this indicator fluidity and

a small fraction of oligomers.

The catalyst according to the invention can be used for the polymerization of olefins containing from 2 to 8 carbon atoms in 1 molecule, and, in particular, for the production of homopolymers of ethylene or copolymers of ethylene with one or more comonomers selected among the olefins described above. These comonomers are predominantly propylene, 1-butene, 1-penten, 3-methyl-1-butene, 1-hexene, 3 - and 4-methyl-1-pentene and 1-octene. Diolefin containing from 4 to 18 carbon atoms can also be copolymerized with ethylene. Diolefine are predominantly aliphatic unpaired diolefin, such as 4-vinyl-cyclohexene, or alicyclic diolefin with nutricology bridge connection, such as Dicyclopentadiene, methylene - and ethylene-norbornene, and aliphatic conjugate diolefin, such as 1,3-butadiene, isoprene and 1,3-pentadiene.

The catalyst according to the invention is particularly well suited for the manufacture of homopolymers of ethylene and copolymers containing at least 90 wt.%, mostly at least 95 wt.% of ethylene. The preferred comonomers are propylene, 1-butene, 1-hexene or 1-octene.

The invention relates To a method of polymerization according to the invention the polymerization can be performed in solution, in suspension in a hydrocarbon diluent or in the gas phase. Good results were obtained when polymerization in suspension.

The polymerization in suspension is carried out in a hydrocarbon diluent, as liquid aliphatic, cycloaliphatic and aromatic hydrocarbons, at a temperature such that at least 80% (mostly at least 90%) formed polymer was it insoluble. Preferred diluents include alkanes with direct chain as n-butane, n-hexane and n-heptane, or alkanes branched chain, such as isobutane, isopentane, isooctane and 2,2-DIMETHYLPROPANE, or cycloalkanes such as cyclopentane and cyclohexane or mixtures thereof.

The polymerization temperature usually selected between 20 and 200oC, mostly between 50 and 150oC, especially between 80 and 115oC. the Pressure of ethylene often choose between atmospheric pressure and 5 MPa, mostly between 0.4 and 2 MPa, in particular between 0.6 and 1.5 MPa. The polymerization can be performed continuously or intermittently in a single reactor or in multiple consecutive reactors; the polymerization conditions (temperature, possible content of co monomer, a possible hydrogen content, the type of environments is, the Scripture which follows below, serve to illustrate the invention. In these examples, first prigotovlyayut carriers for catalysts. Then put the catalysts for these carriers. Thus obtained catalyst media used for the polymerization of ethylene.

The value of the used symbols expressing the above variables and methods of measurement of these quantities are explained below. UE = specific surface of the carrier, as measured by the method of penetration of nitrogen volumetric method British standards BS 4359/1 (1984).

VP = pore volume of the carrier is equal to the sum of the pore volume formed by pores with a radius less than or equal to 75 , as measured by the method of penetration of nitrogen volumetric method British standards BS 4359/1 (1984), and pore volume, measured by a method of mercury penetration using porosimetry type PORO 2000, manufactured in the sale of the company CARLO ERBA CO., according to Belgian standards NBN B 05-202 (1976).

Tc= temperature of crystallization determined using the method specified above.

FD = fraction of oligomers in the sample, expressed in grams of oligomers per kilogram of polymer and measured by hexane extraction with boiling hexane.

= catalytic AK is divided by the partial pressure of olefin, expressed in bars.

Tind= induction time, expressed in minutes and is defined as the time elapsing between the introduction of ethylene and the appearance of the characteristic of the pressure reduction at the beginning of the polymerization.

HLMI = flow index of the polymer with a melting point 190oC, measured at a load of 21.6 kg and expressed in g/min, and American standard ASTM D 1238 (1986).

0/2= the ratio between the dynamic viscosity (0) , expressed in dPa.with and measured by the velocity gradient 1S-1and at 190oC, and the dynamic viscosity (2), expressed in dPa.with and measured by the velocity gradient of 100 S-1and at 190oC.

Examples 1 and 2 (of the invention).

A. Preparation of the precursor gel

a) the First stage

Add drop by drop to a solution of tetraethylene silicon and ethanol, thermostated at 10oC, a solution of water and 1M hydrochloric acid to obtain the concentration of H+0,1 M Number of tetraethylene silicon, ethanol, water and hydrochloric acid, which are used, are presented in table. 1. Then subjected received hydrolytic environment ripening at 60oC for 2 h

b) the Second stage

Prepared water Yu acid; primenyaemye amounts presented in the table. 1. Then add the resulting solution to the hydrolysis medium obtained in (a), with vigorous stirring and at 10oC.

c) the Third stage

Was added to 500 g of an aqueous solution of ammonium hydroxide to pH 8, temperature-controlled at 10oC, the mixture obtained in (b), maintaining the pH constant value of 8 for the implementation of gelation.

(d) Maturation

Were subjected to the gel obtained in (c) ripening with pH 8, for 2 h, under weak stirring and at 60oC.

B. Preparation of catalyst carrier

a) Flushing

Washed the gel obtained in A, first 3 times with water, then 1 times with isopropanol and collected the suspension of the gel in isopropanol.

b) Drying

Subjected to the suspension obtained in (a), spraying through the spray hole diameter of 1 mm into the vessel through which the gas stream containing mainly nitrogen. The gas flow was regulated so that the temperature fell with 300oC at the inlet into the vessel to a temperature of from 80 to 100oC on exit. After spraying the collected particles, the moisture content which was below 1 wt. %.

c) Calcining

Was pricelevel the Raleigh powder media composition (molar percentage of silicon dioxide, aluminum oxide and aluminum phosphate), specific surface area, pore volume and temperature of crystallization are presented in table. 1.

C. Preparation of catalyst

Mixed media obtained in B, with chromium acetylacetonate in an amount such that the mixture contained 0.7 wt. % chromium. Then processed the resulting mixture in the fluidized bed at 150oC for 2 h by blowing dry air. Then progulivali in the fluidized bed at 700oC for 5 h in an atmosphere of dry air and collecting the catalyst.

D. Polymerization of ethylene

In the autoclave with a volume of 3 l, pre-dried and equipped with a stirrer, were administered 100 mg of the catalyst obtained in C, and 1 l of isobutane. Raised the temperature to 104oC and introduced into the autoclave ethylene at a partial pressure of 1.09 MPa. Hydrogen was introduced at a partial pressure of 0.29 MPa. The hydrogen pressure and the temperature was maintained constant during the time required to obtain a certain amount of polyethylene. After degassing the polymer was recuperable in the form of particles whose properties and activity of the catalyst is summarized in table.2.

1. Method of preparation the aluminum oxide and aluminum phosphate, which is mixed in the first stage, alcohol, water. the alcoholate of silicon and acid taken in such quantities that the molar ratio of water and silicon was 2 - 50, and the first stage is carried out at acidic pH by mixing water, acid, silicon alcoholate and alcohol at the temperature during mixing is less than or equal 30oWith and subsequent ripening received hydrolytic environment at a temperature of at least 20oWith and below the boiling point of the medium, thus at least part of alkoxygroup alcoholate of silicon is replaced by hyroxylase without precipitation or gelation of silicon dioxide, obtained in the hydrolysis medium was added in the second stage, the acidic solution of aluminum compounds and/or solution of the phosphate ion source and in the third stage, add the gelling agent, get the gel precursor, and then wash the gel with water and then the organic liquid, collecting the suspension of the gel in the organic liquid, and then subjecting the suspension is dried to obtain a powder and calcined powder, characterized in that the drying is performed by spraying.

2. The method according to p. 1, characterized in that the spraying carried out by spraying a suspension of the gel through the hole of small size is relatively inert gel.

4. The method according to p. 3, characterized in that the gas stream contains mainly nitrogen and contains oxygen.

5. The method according to any of paragraphs.1 to 4, characterized in that the temperature of the gas stream above the 100oC.

6. The method according to p. 5, characterized in that the temperature of the gas stream is 150 to 450oWith the entrance to the spray hole and 20 - 200oWith the end of spraying.

7. The method according to any of paragraphs.1 - 6, characterized in that the spraying is carried out at a pressure of 1 to 10 bar.

8. The catalyst for polymerization of olefins containing chromium on the carrier, and the carrier is the product of the method according to any of paragraphs.1 - 7.

9. The method of polymerization of olefins carried out in the presence of a catalyst, which is used catalyst under item 8.

10. The method according to p. 9, which is subjected to the polymerization of ethylene.

 

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