Title of Invention

AN IMPROVED PROCESS FOR THE PREPARATION FO MAGNESIUM HALIDE SUPPORTED METALLOCENE CATALYST

Abstract

An improved process for the preparation of magnesium halide supported metallocene catalyst . This invention relates to a process for the preparation of the said catalyst, which is supported on magnesium chloride obtained by exploiting the solubility of magnesium chloride into tetrahydrofuran. The catalyst prepared by the process of the present invention is capable of olefin polymerization and co polymerization, giving olefin polymers and copolymers with high catalyst activity and capable of being used at high temperatures without any loss of activity.

Full Text

This invention relates to a>j/process for the preparation of a magnesium halide supported metallocene catalyst. More particularly it relates to the process for the preparation of the said catalyst which is supporied on magnesium chloride obtained by exploiting the solubility of magnesium chloride into tetrahydrofuran. The catalyst prepared by the process of the present invention is capable of olefin polymerization and copolymerization, giving olefin polymers and copolymers with high catalyst activity and capable of being used at high temperatures without any loss of activity. Metallocene based catalyst systems which have been developed recently allow unprecedented control on polyolefin structures through catalyst design and have enabled the synthesis of entirely new families of homo and copolymers. Olefin polymerization catalysts comprising of a metallocene and aluminum alkyl component are well known in the prior art. The molecular weight of the polymer product can be controlled by adjusting the reaction temperature or the amount of cocatalyst or by the addition of hydrogen. These catalysts require use of aluminoxane or cocatalyst, which is produced by reacting an aluminum alkyl with water. Such reaction is very rapid and highly exothermic. Processes for the production of olefins are known with the help of homogeneous catalysts system consisting of a transition metal component of the type, metallocene, and cocatalyst component of oligomeric aluminum compound of the type, aluminoxane ( usually methylaluminoxane, herein after refered to as MAO), which lead to the higher activity with narrow molecular weight distribution polymers or copolymers. Furthermore, US Pat. No. 4, 659, 685, discloses polymerization of olefins with the aid of a solid catalyst comprising a zirconium based metallocene and a cocatalyst consisting of an organoaluminimi compound, especially, MAO. However, this catalyst is preferably used in an aromatic hydrocarbon. It is not suited to heterogeneous processes of polymerization in suspension or in gaseous phase. The principle disadvantages of these soluble homogeneous metallocene-MAO catalyst system are , the need for the large excess of MAO, (Al/Metal > 10^ ) for obtaining reasonable polymerization activities, poor control on polymer morphologies. Furthermore, when used in processes such as gas or slurry, there is a tendency for reactor fouling by forming deposits of the polymer on the surface or the walls of the reactor and stirrer. These deposits result in the agglomeration of the polymer particles when the metallocene and aluminoxanes or both exists in the suspension medium. Such deposits in the reactor system must be removed regularly. Otherwise they prevent adequate heat removal from the reaction, adversely affecting the product.quality. The above disadvantages can be obviated by the use of heterogeneous catalysis, suitable for suspension polymerization in aliphatic and aromatic hydrocarbon medium, and also in gas phase polymerization processes in which it is important to control the size, particle size distribution, and the morphology of the catalyst particle at the same time. Nevertheless, the catalyst should withstand the growth stresses during the course of gas-phase polymerization. It is also desirable that the solid catalyst be capable of producing an ethylene or an ethylenc copolymer with an easily controllable average molecular weight and a narrow molecular weight distribution which is a useful material for injection moulding. A number of patents e.g. JP 05, 125, 112; JP 05, 51, 411; JP 05, 320, 237; JP 05, 186, 524 (Mitsui Toatsu Chemicals) describe magnesium chloride supported zirconium based metallocene catalysts used lor the polymerization of propylene. A few patents are available in the literature for the polymerization of ethylene using magnesium chloride supported metallocene catalysts. According to Eur. Pat. Appl. No. EP 57d, 213 (Mitsubishi Petrochemical Co. Ltd.), polyethylene can be produced with the aid of a solid catalyst comprising of zirconium based metallocene supported on magnesium chloride-2-ethylhexanol. However, the catalyst thus obtained was found to be less active with a relatively broad molecular weight distribution, 3.59. JP 04, 275, 511, (Idemitsu Petrochemical Co. Ltd.) describes another magnesium ethoxide supported metallocene catalyst used for the suspension polymerization of ethylene in n-heptane. However, magnesium alkoxide support depresses polymerization activity. Eur. Pat. Appl. No. EP 435, 514 and EP 436, 326 (BP Chemicals Ltd. ) describes a solid supported zirconocene catalyst useful for the polymerization of ethylene in suspension and also in gas-phase. The support was prepared by a reaction of di-n-butylmagnesium with a tertiary butyl halide in presence of an ether such as diisoamyl ether with or without an alcohol such as, n-butanol in an aliphatic hydrocarbon medium. These catalysts are prepared by a multi step process involving compounds such as ether/alcohols in the catalyst forming steps. Ethers/alcohols are known to react with organoaluminum compounds and hence precise control of their proportions is necessary during catalyst preparation. Otherwise, catalyst with poor or irreproducible properties will be obtained. It is therefore an object of the present invention to provide arocess for the preparation of a magnesium halide supported metallocene catalyst for olefin polymerization and copolymerization catalyst capable of producing high catalyst activity, narrow molecular weight distributions, especially at high temperatures and capable of being used either in gas phase or slurry phase processes. It is also an object of the present invention to provide a catalyst capable of giving olefin polymers and copolymers with excellent particle characteristics and high yield, especially at high temperature and at low aluminum to metal ratio. Another object of the present invention is to simplify the catalyst preparation steps. The present invention relates, therefore, relates to a solid catalyst for polymerization and copolymeriation of olefins, especially ethylene. the solid catalyst consisting of particles having surface area 10 to 70 m-Vg preferably of 15 to 30 m^/g. The said catalyst comprises of a) a support containing from 25 to 50 mol% of magnesium dichloride and from 40 to 80 mol% of at least an electron donor compound (ED), free from labile hydrogen. b) a transition metal compound of a metal belonging to the group 1VB of the Periodic Table containing ligands having a cyclopentadienyl skeleton, the molar ratio of metal/Mg ranging from 0.001 to 0.1. wherein the transition metal compound are supported on the participate magnesium based support. The object of the present invention is designed to rectify the drawbacks of the prior art and to provide a process for the preparation of the supported metallocene catalyst by furnishing a new solid heterogeneous catalyst system, whose preparation involves few steps and is simple. The other object of the present invention is to provide an improved a process for the preparation of a magnesium halide supported metallocene catalyst capable of being employed for the polymerization and copolymerization of olefins especially ethylene, said catalyst comprising atoms of Mg, Cl, an electron donor compound and a neutral metallocene, preferably based on zirconium. The process generally comoprises , a) in the first stage, bringing the magnesium metal into an electron donor solvent in which the magnesium is completely insoluble. b) in the second stage, react the magnesium metal with an organo dihalo alkane compound, where the resultant product will be completely soluble into the electron donor. c) in the third stage, bringing the zirconium metallocene compound into the same electron donor solvent where it will be completely soluble. d) in the fourth stage, admix the product obtained from the second and third stage. e) in the last stage, bringing the product resulting from the fourth stage into a aliphatic hydrocarbon medium where all the components will partially or completely precipitates out. Neutral metallocene with formula [(Cp)a(Cp)bMXx] may be cited as an example wherein X is selected from Cl, Br or I. The mono and dihalide scandium metallocenes such as chlorodi(cyclopentadienyl)scandium, and dichloro(indenyl)scandium, mono, di and trihalides titanium metallocenes, such as chloro- tri(pentamethylcyclopentadienyl)titanium, trichloro(cyclo pentadienyl) titanium, mono, di or trihalides of zirconium such as trichloro(cyclopentadienyl)zirconium, dichloro(biscyclopentadienyl)zirconium metallocene. Among which, the last one is the most preferred. Accordingly the present invention provides, An improved process for the preparation of magnesium halide supported metallocene catalyst comprising one metallocene compound, magnesium metal, one organic dihalogen compound and an electron donor compound and having the general formula MgXa(ED)bMcCpd wherein X is selected from the group consisting of Cl, Br, I, preferably Cl, ED is an electron donor compound, M indicates the transition metal which are chosen from the groups NIB, IVB, VB, VIB of the Periodic Table , Cp represents an unsaturated hydrocarbonic radicle with a central atom M , a is 1 to 30 preferably 2 to 3.5, b is 2 to 80 preferably 1.5 to 3 , c is 0.001 to 0.1 , d is 0.002 to 0.2 , the element Mg is the Arabic numerical one, the said process comprises the steps of : preparing the slurry of magnesium metal in an electron donor solvent such as herein described , heating the slurry of magnesium metal at a range 0°C to 50°C for a period of 10 minutes to 4 hr., adding a dihaloalkane compound to said slurry to obtain a homogeneous solution of the support (solution A), separately preparing the solution of metallocene compound into the electron donor solvent as defined herein (solution B), heating the solution B to 0°C to 50°C for a period ranging between 10 minutes to 1 hr, adding solution B into solution A wherein molar ratio of dichloroalkane / Mg is in the range of 2 to 8, preferably of 3 to 6 and a molar ratio of electron donor/Mg is in the range of 5 to 80, preferably of 15 to 40 and , mixing the two solution for a period ranging between 10 minutes to 2 hrs., keeping the temperature in the range of 0-50°C, cooling the resultant homogeneous solution to room temperature under inert atmosphere, pouring the obtained mixture into a liquid hydrocarbon medium wherein all the components will be partly or completely insoluble to precipitate the catalyst, separating the solid catalyst precipitated by conventional methods, washing the solid catalyst by a hydrocarbon solvent, drying the solid under vacuum at a temperature range between 0 to 50°C to obtain the product. In an embodiment of the present invention the magnesium halide used may be such as chloride, bromide or iodide of magnesium preferably magnesium chloride. In another embodiment of the present invention the electron donor compound may be a generally known as lewis base such as ethers, thioethers, esters, sulphones, sulphoxides, secondary amides, tertiary amines, tertiary phosphines, and phosphoramides, or Electron donor compounds of low complexing power such as cyclic and non-cyclic ethers or alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers and aliphatic ketones. Among the electron donor compounds the preferable ones are alkyl esters of Cj to €4 saturated aliphatic carboxylic acids; alkyl esters of C-j to Cg aromatic carboxylic acids; €2 to Cg and preferably, Cy to €4 aliphatic ethers; CT, to €4 cyclic ethers and preferably €4 mono or di ether, preferably those which would include methyl formate, ethyl acetate, butyl acetate, hexyl ether, tetrahydrofuran, dioxane etc. The electron donor compound should be an organic compound which is liquid at 25 C and in which the metallocene and the magnesium dichloride compound formed during the course of reaction are partially or completely soluble. In another embodiment the dihaloalkanes compound may be a dihalo substituted alkane where the dihalo compound may be chosen from dichloro substituted methane, ethane, propane or butane, most preferably 1,2 dichloroethane. In yet another embodiment the metallocene compound may be selected from the neutral metallocene compound of the formula (Formula Removed) Cp and Cp designate each an unsaturated hydrocarbonic radical with a central atom M. The groups Cp and Cp' can be obtained by a covalent bridge (bond). - M indicates the transition metal which are chosen from the groups IIIB, IV13, VB and VIB of the Periodic Table. - a, b and x designate the integral numbers such as a+b+x = m. x > 0, and a and / or b not equal to zero. - m indicates the valency of the transition metal M - X designates a halogen selected from Cl, Br or 1. In yet another embodiment of the present invention the groups Cp and Cp' each advantageously represents a mono or a polycyclic group substituted with 5 to 50 carbon atoms bond with a double conjugated bond. A typical example may be mentioned of cyclopentaclienyl, indenyl, or a fluorenyl radical or a derivative substituted by this radical containing upto 10 atoms of carbon. It can also work with a radical derived from the elements chosen from the group VA of the Periodic Table, for example, N or P. In yet another embodiment of the present invention the transition metal is selected from scandium, titanium, zirconium, hafnium and vanadium. The zirconium is particularly very convenient. In yet another embodiment of the present invention the catalyst has the formula (Formula Removed) wherein X is selected from the group consisting of Cl, Br, I, preferably Cl. ED is an electron donor compound, M indicates the transition metal which are chosen from the groups IIIB, IVB, VB, VIB of the Periodic Table a is 1 to 30, preferably 2 to 3.5 b is 2 to 80, preferably 1.5 to 3 c is 0.001 to 0.1 d is 0.002 to 0.2 The element Mg is the arabic numerical one. In an embodiment of the the support consists of magnesium halide preferably dichloride and ED in a relative molar percentages of about 25 to 50 mol% preferably of about 30 to 45 mol% and most preferably of about 32 to 40 mol% of magnesium dichloride and from 40 to 80 mol%, preferably from 45 to 75 mol% and especially from 50 to 70 mol% of ED. In yet another embodiment of the present invention the catalyst consists of particles which have a surface area of about 10 to 70 m-/g, preferably of about 15 to 30 m2/g. In an yet another embodimdent of the present invention -the zirconium metalloccnc is present in the solid catalyst with a Zr/Mg molar ratio preferably ranging from 0.001 to 0.1, especially from 0.01 to 0.05. In yet another embodiment of the present invdention the compound used to form the high activity solid catalyst used in the present invention comprises at least one metallocene compound, at least magnesium metal, at least one organic dihalogen compound and at least an electron donor compound. In yet another embodiment of the present invention rnetallocenc is present in the solid catalyst with a Zr/Mg molar ratio preferably ranging from 0.001 to 0.1, especially from 0.01 to 0.05. In embodiment the preferred aliphatic hydrocarbon may be chosen from a group containing C$ to Cg carbon atoms. Precipitation reaction should occur extremely slowly over a period of 4 to 50 h and at a relatively low temperature from 0 to 50 C, preferably 15 to 30 C. In another embodiment various reaclants used for the preparation of the support (A) may be used with a molar ratio of dichloroelhane/Mg is in the range of 2 to 8, preferably of 3 to 6 and a molar ratio of electron donor/Mg is in the range of 5 to 80, preferably of 15 to 40. In a feature of the present invention the Electron Donor compound (ED) must be free from labile hydrogen and cannot be chosen from for example, from water, alcohols, or phenols. The ED must have an ability •to complex magnesium dichloride. In yet another feature of the present invention the organic electron donor compound, ED, is advantageously dirtributed homogeneously throughout the support particles, forming a homogeneous composilion of magnesium dichloride and compound ED. Consequently, a support of this kind cannot be generally be prepared merely by bringing anhydrous magnesium dichloride particles into contact with the compound ED. For this reason it is recommended that the support can be prepared by precipitation of magnesium dichloride in the presence of the compound ED. In another feature the essential characteristics of a solid catalyst is the halide state of neutral metallocene containing at least one cyclopentadienyl ligand in the backbone moiety making a part of the solid catalyst. In a feature of the present invention the solid support, according to the present invention may be prepared by reacting magnesium metals with a dihalo alkane compounds, especially dichloro alkane compounds. In this - case, the presence of electron donor compounds, ED, acting as a complexing agent and not as a reactant, is necessary for the preparation of the particular support (A). In yet another feature of the present invention it is preferred to employ, as electron donor compound, ED, of formula R^OR^ in which R1 and R2 are identical or different alkyl radicals especially containing 1 to 12 carbon atoms. The most preferred electron donor is selected from cyclic ethers compounds of which tetrahydrofuran is the most preferred. The various reactants used lor the preparation of the support (A) can be used with a molar ratio of dichloroethane/Mg is in the range of 2 to 8, preferably of 3 to 6 and a molar ratio of electron donor / Mg is in the range of 5 to 80, preferably of 15 to 40. In yet another feature of the present invention the reaction between magnesium and dichloro alkane in the presence of the electron donor compound, ED, where all the reactant products are soluble in electron donor. The reaction can be done at a temperature of about 0 to 50°C. Yet another feature of the present invention is to prepare an excellent support, in particular, one with a large quantity of electron donor compound is recommended, to per form the reaction at a low temperature ranging from o to 50 C, preferably, from 15 to 30°C. The reaction should proceed very slowly over a period of at least 1/4 to 4 h., preferably from 1/2 to 2 h, so as to allow the reaction to occur completely. A large quantity of electron donor compound is always preferred, so that all the components are soluble in it. It is also advisable to carry out the reaction in anhydrous and inert conditions, for example, under nitrogen or argon atmosphere. The zirconium metallocene (B) is preferably used for the preparation of the solid catalyst in this present invention, which is in the form of a solution in the same electron donor compound. The solution concentration is in the range of 1 to 55 millimoles of zirconium per litre. The contact of solid support (A) which is present in solution of an electron donor, ED, may be brought in contact with zirconium metallocene in various ways. It is possible, to add the zirconium metallocene (B) solution to the support (A) solution or reversely. Addition should be done very slowly over a period of 1/4 h to 4 h, preferably 1/2 h to 2 h, at a relatively low temperature from 0 to 50°C, preferably from 15 to 30°C. The solid catalyst present in solution can be precipitated in an saturated aliphatic hydrocarbon medium where all the components of the solid catalyst will precipitate completely or partially. In yet another feature of the present ivention is that the quantities of the components used for preparing the solid catalyst may be such that a) the molar ratio of Zr to Mg in the solid catalyst is in the range of 2 to 8, preferably 0.01 to 0.05 b) the molar ratio of dichloroalkane to Mg is in the range of 2 to 8, preferably of 3 to 6. c) the molar ratio of electron donor, ED, to Mg is in the range of 5 to 80, preferably 15 to 40. In an yet another feature of the present invention is that the catalyst is obtained in the form of a solid which can be isolated by removing the hydrocarbon solvent employed during the course of catalyst preparation. The solvent may, for example, be evaporated off at atmospheric pressure or at a lower pressure. The solid catalyst may also washed with liquid hydrocarbon, preferably a saturated aliphatic hydrocarbon such as n-hexane or n- heptane. Modification of the support in this manner provides the catalyst composition with increased activity. In an yet another feature of the present invention the solid catalyst has a particular magnesium chloride support containing a relatively large amount of an electron donor compound, ED. The support comprises magnesium dichloride and compound ED in a relatively molar percentages of about 25 to 50 mol%, preferably, of about 30 to 45 mol% and especially, of about 32 to 40 mol% of magnesium dichloride and from 40 to 80 mol%, preferably, from 45 to 75 mol% and especially, from 50 to 70 mol% of the compound ED. In yet another feature the electron donor compound should be an organic compound which is liquid at 25°C and in which the metallocene and the magnesium dichloride compound formed during the course of reaction are partially or completely soluble. The process of the present invention is described herein below with examples which are illustrative only and should not be construed to limit the scope of the present invention in any manner. Example-1 These exaples illustrate the preparation of the catalyst precursor : All glass equipments were heated in vacuo and flushed with nitrogen. All manipulations involving air-sensitive compounds were performed inside a Labconco Model 50004 inert atmosphere glove box continuously purged with high purity N2 from a generator (Spantech Model NG 300-1) or under a positive pressure of high purity N2 using standard bench top inert atmosphere techniques. The solvent n-hexane, xylene and electron donor(tetrahydrofuran) used in each case freshly distilled over sodium under N2- Magnesium was estimated titrimelrically using EDTA. Chlorine was estimated by argeiHometric method. The amount of zirconium in the catalyst was determined by using Inductively Coupled Plasma taking zirconium atomic absorbtion standard solution. Example-2 In a three neck round bottom flask equipped with magnetic needle, reflux condenser, N2 inlet and outlet which was previously flame dried under vacuum and cooled under N2 atmosphere. 0.30 g of magnesium turnings (corresponding to 0.0125 mol of Mg) were taken inside (he flask which was activated by iodine followed by addition of 40 niL of tetrahydrofuran and the slurry was stirred at a temperature of 25 lo 3()°C for 1/2 h. A mixture (10 mL) of 1,2-dichloroethane and tetrahydrofuran (1:1) was added to the slurry by means of a syringe over a period of 1/2 h. It was observed that all the magnesium turnings were slowly dissolved in tetrahydrofuran with the formation of a clear solution. Steady evolution of ethylene gas was also observed indicating the decomposition of the intermediate chloroethyl magnesium complex with the subs quent formation of magnesium dichloride tetrahydrofuran complex and its dissolution into tetrahydrofuran. In another round bottom flask 0.31 g of bis(cyclopentadienyl)zirconium dichloride (corresponding to 1.06x 10 ~3 mol as Zr) was dissolved in 20 mL of tetrahydrofuran and the solution was added to the previous solution over a period of 1/2 h at a temperature of about 25 to 30°C with constant stirring. The whole solution was then transferred into 500 mL round bottom flask containing 300 mL of n-hexane. The white solid precipitates out which was washed three to four times by n-hexane using 50 mL each time. Finally it was dried under vacuum and used as such for polymerization. The solid catalyst thus prepared, containing 0.65 wt% of Zr, 10.wt% of Mg and 65 wt% of THF respectively and a surface area of 18.5 m^/g. ExampIe-3 In a three neck round bottom flask equipped with magnetic needle, reflux condenser, N2 inlet and outlet which was previously flame dried under vacuum and cooled under N2 atmosphere. 0.215 g of Mg turnings (corresponds to 0.01 mol of Mg) were taken inside the flask which was activated by iodine followed by addition of 40 mL of tetrahydrofuran and the slurry was stirred at a temperature of 25 to 30°C for 1/2 h. A mixture (10 mL) of 1,2-dichloroethane and tetrahydrofuran (1:1) was added to the slurry by means of a syringe over a period of 1/2 h. It was observed that all the magnesium turnings were slowly dissolved in tetrahydrofuran with the formation of a clear solution. Steady evolution of ethylene gas was also observed indicating the decomposition of the ntermediate chloroethyl magnesium complex with the subs quent formation of magnesium dichloride tetrahydrofuran complex and its dissolution into tetrahydrofuran. In another round bottom flask 0.243 g of bis(cyclopentadienyl)zirconium dichloride (corresponding to 8.31 x 10 '4 mol as Zr) was dissolved in 15 mL of tetrahydrofuran and the solution was added to the previous solution over a period of 1/2 h at a temperature of about 30°C with constant stirring. The whole solution was then transferred into 500 mL round bottom flask containing 250 mL of n-hexane. The white solid precipitates out which was washed three to four times by n- hexane using 50 mL each time. Finally it was dried under vacuum and used as such for polymerization. The solid catalyst thus prepared, containing 0.0.33 wt% of Zr, 11.1 wt% of Mg and 63.1 wt% of THF. Example-4 In a three neck round bottom flask equipped with magnetic needle, reflux condenser, N2 inlet and outlet which was previously flame dried under vacuum and cooled under N2 atmosphere. 0.40 g (corresponding to 0.0164 mol of Mg) were taken inside the flask which was activated by iodine followed by addition of 60 mL of tetrahydrofuran and the slurry was stirred at a temperature of 25 to 35°C for 1/2 h. A mixture (20 mL) of 1,2-dichloroethane and tetrahydrofuran (1:2) was added to the slurry by means of a syringe over a period of 1/2 h. It was observed that all the magnesium turnings were slowly dissolved in tetrahydrofuran with the formation of a clear solution. Steady evolution of ethylene gas was also observed indicating the decomposition of the intermediate chloroethyl magnesium complex with the subs quent formation of magnesium dichloride tetrahydrofuran complex and its dissolution into tetrahydrofuran. In another round bottom flask 0.42 g of bis(cyclopentadienyl)zirconium dichloride (corresponding to 1.43 x 10 ~3 mol as Zr) was dissolved in 20 mL of tetrahydrofuran and the solution was added to the previous solution over a period of 1/2 h at a temperature of about 25 to 35°C with constant stirring. The whole solution was then transferred into 500 mL round bottom flask containing 300 mL of n-hexane. The white solid precipitates out which was washed three to four times by n- hexane using 50 mL each time. Finally it was dried under vacuum and used as such for polymerization. he solid catalyst thus prepared, containing 0.71 wt% of Zr, 9.40 wt% of Mg and 67 wt% of THF Example-5 In a three neck round bottom flask equipped with magnetic needle, reflux condenser, N2 inlet and outlet which was previously flame dried under vacuum and cooled under N2 atmosphere. 0.40 g (corresponding to 0.0165 mol of Mg) were taken inside the flask which was activated by iodine followed by addition of 50 mL of tetrahydrofuran and the slurry was stirred at a temperature of 25 to 30°C for 1/2 h. A mixture (20 mL) of 1,2-dichloroethane and tetrahydrofuran (1:2) was added to the slurry by means of a syringe over a period of 1/2 h. It was observed that all the magnesium turnings were slowly dissolved in tetrahydrofuran with the formation of a clear solution. Steady evolution of ethylene gas was also observed indicating the decomposition of the intermediate chloroethyl magnesium complex with the subs quent formation of magnesium dichloride tetrahydrofuran complex and its dissolution into tetrahydrofuran. The clear solution obtained from the previous experiment was then transferred to a round bottom flask containing 400 mL of n-hexane when a white solid separated out. The solid was washed three times by n-hexane. Finally it was dried under vacuum. To this solid 60 mL of xylene was added and the mixture was stirred under N2 at a temperature of 70°C. To this mixture 0.42 g of bis(cyclopentadienyl)zirconium dichloride previously dissolved in 40 mL of xylene was added over a period of 15 minutes and the -whole slurry was stirred for 5h maintaining the temperature at 70°C. Finally it was cooled under N2 and to this 400 mL of n-hexane was added. The white solid obtained was washed three to four times by n- hexane using 50 mL each time. Finally it was dried under vacuum and used as such for polymerization. The solid catalyst thus prepared, containing 1.67 wt% of Zr, 9 wt% of Mgand61wt%ofTHF. ExampIe-6 In a three neck round bottom flask equipped with magnetic needle, reflux condensor, N2 inlet and outlet which was previously flame dried under vacuum and cooled under N2 iodine followed by addition of 40 mL of tetrahydrofuran and the slurry was stirred at a temperature of 25 to 30°C for 1/2 h. A mixture (10 mL) of 1,2-dichloroethane and tetrahydrofuran (1:1) was added to the slurry by means of a syringe over a period of 1/2 h. It was observed that all the magnesium turnings were slowly dissolved in tetrahydrofuran with the formation of a clear solution. Steady evolution of ethylene gas was also observed indicating the decomposition of the intermediate chloroethyl magnesium complex with the subs quent formation of magnesium dichloride tetrahydrofuran complex and its dissolution into tetrahydrofuran. In another round bottom flask 0.50 g of bis(cyclopentadienyl)zirconium dichloride (correspond to 1.71 x 10 "^ mol as Zr) was dissolved in 30 mL of tetrahydrofuran and the solution was added to the previous solution over a period of 1/2 h at a temperature of about 50°C with constant stirring. The whole solution was then transferred into 500 mL round bottom flask containing 300 mL of n-hexane. The white solid precipitates out which was washed three to four times by n- hexane using 50 mL each time. Finally it was dried under vacuum and used as such for polymerization. The solid catalyst thus prepared, containing 0.58 wt% of Zr, 10 wt% of Mg and 65 wt% of THF Exaniple-7 In a three neck round bottom flask equipped with magnetic needle, reflux condenser, N2 inlet and outlet which was previously flame dried under vacuum and cooled under N2 atmosphere. 0.30 g (corresponding to 0.0164 mol of Mg) were taken inside the flask which was activated by iodine followed by addition of 40 mL of tetrahydrofuran and the slurry was stirred at a temperature of 25 to 30°C for 1/2 h. A mixture (10 mL) of 1,2-dichloroethane and tetrahydrofuran (1:1) was added to the slurry by means of a syringe over a period of 1/2 h. It was observed that all the magnesium turnings were slowly dissolved in tetrahydrofuran with the formation of a clear solution. Steady evolution of ethylene gas was also observed indicating the decomposition of the intermediate chloroethyl magnesium complex with the subs quent formation of magnesium dichloride tetrahydrofuran complex and its dissolution into tetrahydrofuran. In another round bottom flask 0.31 g of bis(dienyl)zirconium dichloride (correspond to 1.06x 10 ~3 mol as Zr) was dissolved in 20 mL of tetrahydroi'uran and the solution was added to the previous solution over a period of 1/2 h at a temperature of about 25 to 30°C with constant stirring. The whole solution was then transferred into 500 mL round bottom flask containing 300 mL of n-hexane. The white solid precipitates out which was washed three to four times by n- hexane using 50 mL each time. Finally it was dried under vacuum and used as such for polymerization. The solid catalyst thus prepared, containing 0.52 wt% of Zr, 10 wt% of Mgand68 wt%ofTHF. We Claim: 1. An improved process for the preparation of magnesium halide supported metallocene catalyst comprising one metallocene compound, magnesium metal, one organic dihalogen compound and an electron donor compound as described herein and having the general formula MgXa(ED)bMcCpd wherein X is selected from the group consisting of Cl, Br, I, preferably Cl, ED is an electron donor compound, M indicates the transition metal which are chosen from the groups NIB, IVB, VB, VIB of the Periodic Table , Cp represents an unsaturated hydrocarbonic radicle with a central atom M , a is 1 to 30 preferably 2 to 3.5, b is 2 to 80 preferably 1.5 to 3 , c is 0.001 to 0.1 , d is 0.002 to 0.2 , the element Mg is the Arabic numerical one, the said process comprises the steps of : preparing the slurry of magnesium metal in an electron donor solvent such as herein described , heating the slurry of magnesium metal at a range 0°C to 50°C for a period of 10 minutes to 4 hr, adding a dihaloalkane compound to said slurry to obtain a homogeneous solution of the support (solution A), separately preparing the solution of metallocene compound into the electron donor solvent as defined herein (solution B), heating the solution B to 0°C to 50°C for a period ranging between 10 minutes to 1 hr , adding solution B into solution A wherein molar ratio of .dichloroalkane / Mg is in the range of 2 to 8, preferably of 3 to 6 and a molar ratio of electron donor/Mg is in the range of 5 to 80, preferably of 15 to 40 and , mixing the two solution for a period ranging between 10 minutes to 2 hrs, keeping the temperature in the range of 0-50°C, cooling the resultant homogeneous solution to room temperature under inert atmosphere, pouring the obtained mixture into a liquid hydrocarbon medium wherein all the components will be partly or completely insoluble to precipitate the catalyst, separating the solid catalyst precipitated by conventional methods, washing the solid catalyst by a hydrocarbon solvent, drying the solid under vacuum at a temperature range between 0 to 50°C to obtain the desired solid catalyst. 2. An improved process as claimed in claim 1 wherein the magnesium halide used is selected from chloride, bromide or iodide of magnesium preferably magnesium chloride. 3. An improved process as claimed in claims 1 and 2 wherein the electron donor compound used is selected from ethers, thioethers, esters, sulphones, sulphoxides, secondary amides, tertiary amines, tertiary phosphines, and phosphoramides, or Electron donor compounds of low complexing power such as cyclic and non-cyclic ethers or alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers and aliphatic ketones, preferably alkyl esters of Ci to C4 saturated aliphatic carboxylic acids; alkyl esters of C7 to C8 aromatic carboxylic acids; 62 to C6 and preferably, C3 to C4 aliphatic ethers; C3 to C4 cyclic ethers and preferably C4 mono or di ether, preferably those which would include methyl formate, ethyl acetate, butyl acetate, hexyl ether, tetrahydrofuran, dioxane . 4. An improved process as claimed in claims in 1 to 3 wherein the dihaloalkanes compound may be a dihalo substituted alkane where the dihalo compound may be chosen from dichloro substituted methane, ethane, propane or butane, most preferably 1,2 dichloroethane. 5. An improved process as claimed in claims 1 to 4 wherein the metallocene compound used is such as neutral metallocene compound of the formula (Cp)a(Cp')b M Xx , wherein Cp an Cp' designate each an unsaturated hydrocarbonic radical with a central atom M, the group Cp and Cp' can be obtained by a covalent bridge (bond), M indicates the transition metal which are chosen from the groups 1MB, IVB, VB and VIB of the Periodic Table, a, b and x designate the integral numbers such as a + b + x = m, x > 0, and a and/or b not equal to zero, m indicates the valency of the transition metal M, X designates a halogen selected from Cl, Br or I. 6. An improved process as claimed in claims 1 to 5 wherein the groups Cp and Cp' each advantageously represents a mono or a polycyclic group substituted with 5 to 50 carbon atoms bond with a double conjugated bond selected from the group consisting cyclopentadienyl, indenyl, fluorenyl radical or a derivative substituted by this radical containing upto 10 atoms of carbon and may work with a radical derived from the elements chosen from the group VA of the Periodic Table . 7. An improved process as claimed in claims 1 to 6 wherein the transition metal is selected from scandium, titanium, zirconium, hafnium and vanadium preferably zirconium. 8. An improved process as claimed in claimed in claims 1-7 wherein the solution A used is comprising a magnesium halide preferably dichloride and a electron donar compound (ED) in a relative molar percentages of ranging 25 to 50 mol% preferably of 30 to 45 mol% and most preferably of 32 to 40 mol% of magnesium dichloride and from 40 to 80 mol%, preferably from 45 to 75 mol% and especially from 50 to 70 mol% of ED. 9. An improved process as claimed in claim 1 to 8 wherein the solid catalyst obtained is consisting of particles, which have a surface area of about 10 to 70 m2/g, preferably of about 15 to 30 m2/g. 10. An improved process as claimed in claims 1 to 9 wherein the metallocene present in the solid catalyst is Zirconium mettallocene having a Zr/Mg molar ratio ranging from 0.001 to 0.1, preferably from 0.01 to 0.05. 11. An improved process for the preparation of magnesium halide supported metallocene catalyst substantially described hereinbefore with references to examples.

Documents:

795-del-1997-abstract.pdf

795-del-1997-claims.pdf

795-del-1997-complete specification (granted).pdf

795-del-1997-correspondence-others.pdf

795-del-1997-correspondence-po.pdf

795-del-1997-description (complete).pdf

795-del-1997-form-1.pdf

795-del-1997-form-19.pdf

795-del-1997-form-2.pdf

795-del-1997-form-3.pdf

795-del-1997-petition-124.pdf

795-del-1997-petition-137.pdf