Title of Invention	A METHOD FOR PREPARING A CATALYTIC COMPOSITION FOR THE OLEFIN POLYMERIZATION
Abstract	Abstract PREPARATION OF A CATALYTIC PASTE FOR THE OLEFIN POLYMERIZATION A method for preparing a catalytic composition for the olefin polymerization in the form of a dispersion of catalyst particles in a semi-fluid matrix, characterized in that it comprises the steps of: a) forming a suspension of catalyst particles in oil by loading under a continuous stirring dry catalyst powder into a tank containing said oiL the load velocity of the catalyst powder per or of oil interface being less of 800 kg/h+ m2; b) adding under stirring a molten thickening agent having a melting point in a range from 30 to 70 C. while maintaining the catalyst suspension in oil at a temperature such that said thickening agent solidifies on contact with said suspension.

Title of Invention

A METHOD FOR PREPARING A CATALYTIC COMPOSITION FOR THE OLEFIN POLYMERIZATION

Abstract

Abstract PREPARATION OF A CATALYTIC PASTE FOR THE OLEFIN POLYMERIZATION A method for preparing a catalytic composition for the olefin polymerization in the form of a dispersion of catalyst particles in a semi-fluid matrix, characterized in that it comprises the steps of: a) forming a suspension of catalyst particles in oil by loading under a continuous stirring dry catalyst powder into a tank containing said oiL the load velocity of the catalyst powder per or of oil interface being less of 800 kg/h+ m2; b) adding under stirring a molten thickening agent having a melting point in a range from 30 to 70 C. while maintaining the catalyst suspension in oil at a temperature such that said thickening agent solidifies on contact with said suspension.

Full Text	The present invention relates to a method for preparing a catalytic composition in the form of cataiyric panicles dispersed in a semi-fluid matrix, the catalytic composition Demg suitable to be transferred and fed into a reactor for the olefin polymerization. The present invention also relates to a process for the polymerization of olefins carried out in the presence of a polymerization catalyst comprising a solid catalytic component dispersed in a semi-fluid matrix. It is widely known in the art that catalytic components of the Ziegler/Natta type comprising a titanium compound supported on magnesium chloride show a high activity in the polymerization of olefins. These catalytic components are indeed the most extensively used in the polymerization of olefins such as ethylene, propylene, etc. and are obtained in a powder form by reacting a titanium compound comprising at least a titanium-halogen bond with a solid support comprising a magnesium halidc. In a continuous process for the olefin polymerization it is largely felt the need of continuously feeding the catalyst particles at a constant flow rate to the polymerization reactor, Furthermore, the solid catalytic components have to be transferred to the polymerization reactor without a significant modification of their morphology and other physical properties, such as porosity, surface area, etc., also trying to achieve a homogeneous distribution diereof inside the gas or liquid medium used as the carrier. A method of transferrina the solid catalyst particles to die pohTnerizarion apparatus consists in forming a suspension of the catalytic particles in a liquid hydrocarbon and then snecessivery pumping die obtained suspension into the pressurized reaction system. However, this method does not allow an accurate dosage of the catalyst panicles in the porymerizarioii apparams and moreover, it may cause the breaking of some catalytic particles, either during me stirring of the suspension, or during the subsequent pumping. The breaking of mc catalyst with consequent formation of particles of reduced size (fines) is particularly detrimental, since the catalyst particles must have a predetermined morphology, which is strictly conelated to the morphology of the polymer targeted to be prepared. In order to facilitate hs dosage and transfer, die catalyst powder can be combined with a wax. which makes rt possible continuously feeding a waxed catalyst into the polyinerizarion rcacEs-. By way of example, reference is made to US 4,158,571 and US 4.182,817 disclosing a method for feeding solid catalyst particles to a polymerization reaction system. These patents teach the preparation of a semi-solid paste containing dispersions of at least one functional material, such as a polymerization catalyst, uniformly dispersed throughout a continuous solid phase. Said continuous solid phase has tbe theological features of a Bingham fluid and consists essenrialiy of an intimate mixture of a wax and a liquid hydrocarbon. The preparation of this catalytic paste comprises a first step of heating and mixing together the desired proportions of a molten wax and a liquid hydrocarbon in stirred vessel, and successive step involving the addition of the finely-divided solid catalyst to the above obtained mixture. The mixture is agitated with sufficient intensity to disperse the finely-divided solid catalyst uniformly throughout the melt, after which the entire composition is cooled until it solidifies. Preferred waxes used in the above preparation method are petroleum waxes. Notwithstanding die obtained composition is useful to achieve an accurate dosage and transfer of the dispersed catalyst to the polymerization apparatus, the method described in US 4.158.571 and US 4,182.817 is such that little amounts of wax can easily penetrate inside tbe pores and on the surface of the catalyst particles: as a consequence, the obtained eaiafyrk paste shows drawbacks in the successive step of activation with organo^umimrni compounds and also in case of prepolymerization (T=20-30°C), since tne occfasJoc even partial, of tiie catalyst pore and surface caused by zhs sotiuificaiioa of me was generates problems in achieving a satisfying activation of the catalytic sites, which leads TO a low catalyst activity in polymerization. Other drawbacks are correlated with the preparation of a semi-solid catalytic paste. For instance, the method described in US 4,898,847 uses a paraffmic hydrocarbon with a melting point 5O-70DC or an atactic polypropylene, which is deposited on a supported catalyst suspended in hydrocarbon solvent. Successively, according to the description of this patent, it is advantageous to remove said hydrocarbon solvent, for instance, by decantation or by evaporation with stirring, in order to achieve an uniform coating of the supported catalyst with the above paraffmic hydrocarbon. This additional step of WO 00/47638 relates to a polymerization catalyst system obtained by a process comprising a first activation step, wherein a solid transition metal compound is contacted whh a first orgaiKKaiuminiim compound in the presence of a oil to give a first reaction mixture, and a second activation step including the contact of said first reaction mixture with a second organo-aluminum compound According to an alternative embodiment, the first activation step can be carried out in the presence of an oil mixed together with a component selected from a wax, fat or solid paraffin. The aim of the process described in WO 00/47638 is to reach a mild activation of the solid transition metal compound by means of the organo-aluminum compound. By adding some oil to the first activation step a smooth, suppressed reaction between the solid transition metal compound and the first organo-aluminum compound is accomplished. The description of WO 00/47638 refers to the step of preactivaring the catalyst components in the presence of oil and a wax/paraffin: this patent fails to provide an useful teaching on how to preserve the catalyst morphology in the line connecting the catalyst powder storage and the polymerization reactor. It would be largely desirable to overcome the above drawbacks correlated with the prior art methods to prepare a catalytic paste, providing an alternative preparation method able to preserve me catalyst morphology throughout me line connecting the catalyst powder storage and me polymerization reactor. The Applicant has now foetid diai a continuous dosage and transfer of solid catalyst particles to a porymerization reactor can be successfully performed without substantially altering their morphology and porosity by the incorporation of the catalyst particles in a suitable serm-fhrid matrix-It is therefore a first object of the present invention a method for preparing a catalytic composition for the olefin polymerization in the form of a dispersion of catalyst particles in a semi-fluid matrix, characterized in that it comprises the steps of: a) forming a suspension of catalyst particles in oil by loading under a continuous stirring dry catalyst powder into a tank containing said oil. the load velocity of the catalyst powder per m" of oil interface being less of 800 kg/hm"; bi adding under stirring a moiisE thickening agent having a melting point in a range from 50 tc ~0"C. while maintaining the catalyst suspension in oil at a TcmperaiurE such, thai said thickening agent solidifies on contact with said suspension. According to the invention, "oil interface" is intended as the surface separating the liquid oily phase from the above gaseous phase in the tank of step a), while maintaining the oil in a motionless condition. In case of a common tank with a circular cross section, the oil interface is therefore given by me area of die circle having me internal diameter of me tank as its diameter. According to the method of the invention, a mixing tank is first filled with oil. Being the catalyst extremely sensitive to oxygen and moisture, the oil fed to the mixing tank is degassed by storage under inert atmosphere and dried by a nitrogen flow: this removes traces of humidity and oxygen. The catalyst powder is stored inside a drum under an inert atmosphere and from this drum the catalyst is discharged and loaded into the tank containing the oil. According to a preferred embodiment of the invention, the solid catalyst particles introduced into the tank containing oil of step a) are Ziegler-Natta catalytic components based on a titanium halide, preferably TiCU, supported on magnesium halide. Oil and thickening agents used in the present invention are necessarily inert compounds towards the catalyst system, dial is ro say oil and tfiickening agents cannot react with the catalyst components, snch as the solid component the donor compounds and the The catalyst powder is added slowly to the oil in order to promote me immediate dispersion of die catalyst in oil and. above all. to avoid accumulations of solid catalyst on the oil upper surface, h has been observed that a high load velocity of the catalyst is detrimental in achieving an acceptable dispersion of catalyst particles in die oil. since it causes the agglomeration of the solid particles with formation of many lumps, not easily dispcrsible in the oil. Therefore, in step a) the catalyst load velocity per m" of oil interface is generally kept at a value of less than 800 kg/h-m2. preferably in a range from 200 to 500 ka/h.ml The above load velocity of the cs:a;ysi powder may be adjiisted by means of a funnei- shape discharge 21 the botton of me drum co-taming the catalyst powder. According to a preferred embodiment of me invention, the above load velocity of the catalyst is adjusted by means of an L-varvc, in which the flow rate of catalyst entering the mixing tank of step a> is kept at the desired vaiue by means of regulation of a nitrogen flow. The formation of the suspension of catalyst in oil (step a) is generally carried out under continuous stirring by keeping the temperature above 50°C, preferably in a range from from 60 to 90CC under an inert atmosphere. The feeding of oil and catalyst to step a) is such to form a suspension of catalyst particles in oil with a solid concentration ranging from 80 gl to 500 g1, preferably 150-350 g/1. The stirring intensity of the suspension is preferably the minimum necessary to avoid me settling of the catalyst powder. The peripheral velocity of the stirring device is generally maintained at a value lower than 0.7 m/s, preferably comprised between 0.4 and 0.6 m/s. Oil is defined as a hydrocarbon or hydrocarbons mixture, which is liquid at room temperature and with a relatively low vapor pressure. The oil used for preparing the catalyst suspension of step a) can be selected from mineral oils, synthetic oils, with the proviso of being inert towards the catalyst components. Preferred mineral oils are paxaffmic white oils and. among these, vaseline oils. White oils are colorless, odorless, tasteless mixtures of saturated paraffinic and naphthenic hydrocarbons. These nearly chemically inert oils are virtually free of nitrogen, sulfur. oxygen and aromatic hydrocarbons. Suitable white oils are OB22 AT. Wiuog 70. Fina Vestan A 360B and Shell Ondma 64. Synthetic oils can be obtained, for instance, by the oligomerization of decene, fractionating the product to an average of 30 carbon atoms and successive hydrogenation. It has been observed that a low viscosity of the oil contributes to maintain unchanged the particle size distribution of the catalytic particles during step a) and b) of the present invention. As a consequence, the dynamic viscosity of the oil at 20CC is preferably comprised between 10 and 400 cPs, more preferably between 20 and 200 cPs. stirring for a rime preferably comprised between 30 minutes and 3 hours, in order to assure a complete weeing and dispersion of the catalyst particles. In the case the catalytic component contains a high amount of volatile compounds, step a) may be favorably carried out under vacuum. Once prepared, the oil-catalyst suspension is preferably cooled at a temperature generally comprised between 2 and 25CC, before adding the molten thickening agent of step b), this component being previously degassed by storage under inert atmosphere to eliminate traces of humidity and oxygen. The thickening agent used in the present invention is a solid or semi-solid substance at room temperature, having a melting point in the range from 30 and 70°C. Suitable compounds are selected from petrolatum and waxes with a melting point in the range from 30 and 70CC. Petrolatum is a natural mixture of microcrystallinc wax and oiL, obtained by fractional distillation of petroleum, as the byproduct of the heaviest lubricating oil fraction. When fully refined it becomes microcrystaliine wax. The preferred waxes used in the present invention are paraffin waxes, in particular vaseline (commonly named also "vaseline grease"). Paraffin waxes contain Ci^-C-= The method of the invention preferably uses molten vaseline as the thickening agent of step b>. Said component is fed into the tank containing the suspension of catalyst in oil at a feeding temperature in a range from 75= to 110°C preferably from. 85 to 105°C. The molten thickening agent is slowly fed while stirring the oil'catalyst mixture with a peripheral speed of the stirring device as mentioned for step a). Due to the low temperature of the catalyst suspension, the molten thickening agent solidifies almost instantaneously in flaky particles which disperse in the oil, further lubricating the overall system. The thermal capacity of the suspension is sufficient to ensure the instantaneous solidification of the thickening agent during its progressive feeding into e sispessioTL To sins ais it is preferable to refrigerate the suspension of catalyst in oil during step b) to maintain its Temperature in a range comprised between 2"C and 25'JC, mus avoiding 233- increase of temperature which would hinder a prompt solidification of me ririckening agent. At the end of the addition of the thickening agent, a semi-solid catalytic paste is obtained in which no phase separation (oil phase or solid phase) is observed- The amount of mohen dnckening agent added during step b) is sufficient to form a stable semi-fluid matrix, in which the catalyst particles remain suspended. The weight ratio of thickening agent with reference to the total amount of oil and thickening agent is generally comprised between 0.35 and 0.5, with concentrations of catalyst in the catalytic paste between 50 and 500 g/1. Preferably, said weight ratio is comprised between 0.3 and 0.4, with catalyst concentrations between 200 and 300 g/1. Is is clear Shat lower catalyst concentrations imply a higher weight ratio of thickening agent, since the catalyst itself acts as a thickener. At the end of the addition of the thickening agent, the semifluid catalytic paste is further cooled, always under stirring, to a temperature generally lower than 25=C, preferably comprised between 0DC and 15°C. In these conditions the catalytic composition may be transferred in metering syringes suitable to allow the feeding of the catalyst to the reaction system wim an accurately controlled flow rate. The method according to me present invention allows prepare a semi-fluid catalytic paste with many correiaied technical advantages. Step a) of the invention is carried out with specific operative conditions, so as to assure a complete wetting of the catalyst particles, including the particle pores, so that the imerposttion of an oil layer hinders an accidental direct friction between the catalyst particles. This contributes to preserve the morphologic properties of the catalytic particles during the preparation of the catalytic composition, avoiding an undesired formation of excessively low size particles of polymer (fines) during the successive prepolymcrization and polymerization of alpha-olefins. Moreover, the addition of a thickening agent during step b) does not affect the surface and pores of the catalyst particles. The latter are therefore separated from the oiithickrening agent mams by an oii layer. which is easily and quickly removable in the successive steps of catalyst activation, nrepoiyraerizarion and polymerization. Other advantages and features of die present invention arc illustrated in the following detailed description with reference to me attached drawing, which is representative and not iimkathe of the scope of the invention. Figure ! shows a preferred embodiment to carry out the present invention, wherein a L- valve is used to adjust the load velocity of the catalyst powder in step a). Also me devices and lines suitable to convey the catalytic composition of the invention up to the polymerization reactor are schematically shown in Fig.I, as well as the steps of catalyst activation and prcpolymerization. With reference to Figure 1, a solid catalytic component is stored in the form of a dry powder inside the drum 1, while the vessel 2 contains oil and the vessel 3 contains the thickening agent (TA). A tank 4 endowed with a stirring device 5 is used to prepare the catalyst suspension of step a). The tank 4 is first filled with the oil coming from the vessel 2 via line 6. Afterwards the catalyst particles are discharged from die drum 1 via line 7 and enter a L-valve 8, which is used for adjusting the velocity of catalyst load into the mixing tank 4. The flow rate of catalyst powder introduced into the mixing tank 4 is kept at the desired value by a control valve 9 adjusting a stream of nitrogen which enters the L- valve 8 via line 10. When die feeding of the catalyst powder in the tank 4 is completed, the mixture is mainained under stirring ibr the schabie rime io order to assure a complete » etting and dispersion of me catalyst particles in me oil. Once prepared, the oil/catalyst suspension is successively cooled, and men me molten thickening agent coming from the vessel 3 is fed into the tank 4 via line 11. The molten thickening agent is slowly fed, while continuously stirring the oil/catalyst mixture inside the tank 4. Due to the low temperature of the catalyst suspension, the molten thickening agent solidifies almost instantaneously in flaky particles which disperse in the oil. When the feeding of the thickening agent is completed, a stable semi-solid catalytic paste is obtained in which no phase separation (oil phase or solid phase) is observed: the catalyst particles remain suspended in the semi-solid paste. The catalytic paste is then As shown m Fig.l the catalytic paste is withdrawn from the mixing tank 4 avoiding the use ot a discharge varvc, e.g. 3 bail valve, bur using a device capabic of withdrawing the dispersion of catalyst in tha semi-solid matrix without rough movements. A dosing syringe 12 is used for softly withdrawing the catalyst paste from the tank 4 and softly pushing it into line 13a and 13b. Moreover, a couple of two dosing syringes 14 and 15 is exploited for ensuring a continuous and delicate metering of catalytic paste to the successive step of catalyst activation. While the syringe 14 is filled with catalytic paste coming from line 13a, the second syringe 15 pushes and transfers the catalytic paste to line 16. Likewise, when the syringe 15 is filled with catalytic paste coming from line 13b, the first syringe 14 pushes and transfers the catalytic paste to line 16 and consequently to the activation vessel 17. An organo-aluminum compound as the catalyst activator is fed via Sine 18 to the activation vessel 17. Also a hydrocarbon solvent such as propane, is conveniently fed to the activation vessel 17 via line 19, optionally together with an electron donor compound. The activated catalyst system is hence discharged from the activation vessel 17 and fed via line 20 to a loop reactor 2 J used to carry out the prepolymerization of the catalyst. Line 20 merges into an olefin pick-up 22. which is the feeding line of the olefin to the loop reactor 21. The prepofyTnerized catalyst system is successively fed via line 23 to the polymerization reactor (not shown). As explained in connection with Fig. 1, the semi-fluid catalytic paste prepared by means of me method of the invention is particularly suitable to be transferred and treated in one or more successive steps in order to have a controlled flow rate of catalyst system introduced into the polymerization reactor. It is therefore a second object of me invention a process for the polymerizarion of olefins carried out in the presence of a solid polymerization catalyst, the process being characterized in that said solid polymerization catalyst is treated and transferred to the polymerization reactor by the following steps: a) forming a suspension of catalyst particles in oil by loading under a continuous As explained, method of the present invention implies that the presence of the thickening agent is confined to the semi-solid matrix, which maintains the catalyst particles in a stable dispersion. Different from the catalytic pastes described in the prior an patents, the thickening agent docs not penetrate inside the pores and on the surface of die catalytic particles: this makes the catalyst particles to be efficiently activated by means of the contact with an organo-aluminum compound able to reach the catalytic sites inside the particles pores. Moreover, the catalyst particles enter the reaction system The analysis comprises the addition of the sample, under nitrogen flow, to a measure cell containing hexane and provided with a stirrer and with a circulation pump having a flow rate comprised between 70 and 100 1/h. The measure is performed while the suspension is circulated. The central process unity of the analyzer processes the obtained from the bottom discharge of the stirred tank, were added to 50 cm" of hcxanc, and die stirred suspension in hcxanc was analyzed. A slurry of polypropylene in propylene was continuously discharged from the loop reactor and was subjected to healing in a jacketed pipe up to the temperature of &5CC before entering a flash drum, wherein the monomer evaporation and the polymer separation from the slurry were performed. Tne catalyst mileage was of -^OKg of porymer per g of catalyst and the obtained po.Vpropyiene had a Men Index MIL of 66 g'10\ as indicated in Table 2. A sample of the obtained polymer was dried at 70°C. under nitrogen flow for 3 hours, and then subjected to PSD analysis: spherical particles of polypropylene with an average diameter from 0.1 mm to 4 mm and an amount of fines (diameter 0.4% by weight were obtained. Example 2A - Preparation of the catalytic paste - STEP A) - White oil Winog 70 (supplier Tudapetrol) having a dynamic viscosity of 8.5 cPs at 100°C was used in this example. The same stirred tank of Example 1A was used for preparing the catalytic paste according to the method of the invention. 165.7 Kg of white oil Winog 70 were charged in the stirred tank at room temperature. The oil temperature was then increased up to reach the value of 70CC inside the stirred tank, while continuously stirring at a stirring velocity of 15 rpm. Successively 85 Kg of dry catalyst: powder were loaded to the stirred tank in a time of 20 minutes. Takmg into account that the oil interface area was about 0 J m\ the catalyst load velocity per m" of oil interface was equal to 510 Kg'nrh, that is to say a value according to me r^a-.-rrnc of me pressnr invention. At me end of the catalyst load, the catalyst suspension was continuously subjected to stirring at 15 rpm for U hour mamrammg the temperature at 70=C. Afterwards, the catalyst suspension was cooled to 20CC by circulation of cooling water in the external jacket of the stirred tank. - STEP B) - 71 Kg of molten Vaseline Pionier 17122 (supplier Tudapetrol) were fed to the tank containing the catalyst suspension at a feeding temperature of 90°C. The addition of the molten vaseline was carried out from the top of the tank, while maintaining the tank under stirring at 15 rpm. At the end of the addition of the molten vaseline, the The catalytic paste was withdrawn by the stirred tank by a dosing syringe and then continuosly transferred by means of two dosing syringes to a catalyst activation vessel. Triethylaiuminium (TEAL) as the cocatajyst, and cyclohexylmethyldimethoxysilane (CHMMS) as an external donor were introduced into the activation vessel, with a weight ratio TEAL-Ysolid catalyst) of 10.5 and a weight ratio TEAL/CHMMS of 25. Propane as a diluent was also fed to the catalyst activation vessel. The above components were pre-contacted in the activation vessel at a temperature of 10CC for 20 minutes. Propylene was polymerized in the loop reactor using Hj as the molecular weight regulator. Ethylene was also fed to die loop reactor in an amount of 0.3% by moL Make-up propylene and hydrogen as molecular weight regulator were continuously fed to the loop reactor. The polymerization of propylene was carried out at a temperature of 70°C and at a pressure of 3.4 MPa. A slurry of polypropylene in propylene was continuously discharged from the loop 543 Kg of molten vaseline BF were fed to the tank containing the catalyst suspension at a feeding temperature of 90=C. The addition of the molten vaseline was carried out from the top of the tank, while maintaining the tank under stirring at 15 rpm. At the end of the addition of the molten vaseline, the temperature of the catalytic paste was decreased to regulator were fed to the recycle gas line of the reactor. The polymerization of propylene was carried out at a temperature of 80°C and at a pressure of 2.0 MPa. The catalyst mileage was of 20Kg of polymer per g of catalyst. It can be seen from Triethylalinnmium (TEAL) as the cocatalyst and cyclohexylmerhyldimcthoxysilanc (CHMMS) as an external donor were fed to the activation vessel. The same operative conditions of Example IB were performed. - Polymerization - The prepolymerized catalyst was discharged from the loop prepotymerizator and was continuously fed to a liquid loop reactor together with propylene as the monomer and hydrogen as the molecular weight regulator. The polymerization of propylene was carried out according to the same operative conditions of Example IB (T=70°C, p=3.4 MPa). A slurry of polypropylene in propylene was continuously discharged from the loop reactor and was subjected to heating in a jacketed pipe up to the temperature of 85DC before entering a flash drum, wherein the monomer evaporation and the polymer separation from the slurry were performed. The catalyst mileage was of 40K_g of polymer per g of catalyst and the obtained polypropylene had a Melt Index MIL of 68 g/10'. as indicated in Table 2. A sample of the obtained polymer was dried at 70CC, under nitrogen flow for 3 hours, and then subjected to PSD analysis: spherical particles of polypropylene with an Successively 40 Kg of dry catalyst powder obtained by the above described procedure were loaded to the stirred tank in a time of 4 minutes. Taking into account mat me oil interface area was about 0.5 m2, the catalyst load velocity per m2 of oil interface was equal to 1200 Kg'm2h, outside the range claimed in the present invention. -STEPB)- 25.6 Kg of molten vaseline BF were fed to the tank containing the catalyst suspension at a feeding temperature of 95:C. The addition of the molten vaseline was carried out from me top of the tank, while maintaining the tank under stirring at 15 rpm. At the end of the addition of the mohsn vaseline, the temperature of the catalytic paste was decreased to I0°C: at this temperature, the catalytic paste containing about 300 Kg/m3 of solid catalyst powder, was still sufficiently fluid to be discharged from the stirred tank by means of a dosing syringe. The particle size distribution (PSD) analysis of the catalyst powder suspended in the semi-fluid catalytic paste was performed. The granulometric distribution of the catalyst in the catalytic paste gave a negative result showing a high amount of fine particles: owing to particles breakage during the preparation of the paste the fraction having d CLAIMS: conriniious stirring dry catalyst powder into a tank containing said oil. the load velocity of die catalyst powder perm2 of oil interface being less of 800 kg/hm2; b) adding under stirring a molten thickening agent having a melting point in a range from 30 to 70:C. while maintaining the catalyst suspension in oil at a temperature such that said thickening agent solidifies on contact with said suspension. 2. The method according to claim 1, wherein the load velocity of catalyst powder in step a) is comprised in a range from 200 to 500 kg/h-m2. 3. The method according to claim 1, wherein said load velocity in step a) is adjusted by means of an L-varve. 4. The method according to any of claims 1-3, wherein the formation of said suspension of catalyst in oil in step a) is carried out under continuous stirring by keeping the temperature in a range from 60 to 90=C under an inert atmosphere. 5. The method according to claim 1. wherein in step a) a suspension of catalyst particles in oil whh a solid cracenrrarion ranging from 80 gl to 500 gl is mineral oils, synthetic oOs. The method according H) claim 6. wherein said oil is a paraffinjc white oiL 8. The method according to claims 6-7. wherein said oil has a dynamic viscosity at I00°C comprised between 1 and 12 centiPoise (cPs). 9. The method according to claim I, wherein said catalyst particles introduced into uie rank of step a) are Ziegier-Nana catalytic components based on a titanium halide supported on magnesium halide. 13. The method according to any of claims 1-12, wherein said temperature at which mc catalyst suspension in oil is kept during step b) ranges from 2°C to 25°C. 14. The method according to claim 1. wherein the weight ratio between said thickening agent and the total amount of oil and thickening agent is comprised between 0.15 and 0.5. 15. The method according to any of claims 1-14, wherein a catalytic paste with catalyst concentrations between 50 and 500 gl is obtained from step b). 16. A process for the polymerization of olefins carried out in the presence of a solid polymerization catalyst ihe process being characterized in that said solid polymerization catalyst is treated and transferred to the polymerization reactor by the following steps: b) adding under storing a mohsn thickening agent having a melting point in a range from 30 ro 70C. while maintaining rhe catalyst suspension in oil at a temperature such thai said thickening agent solidifies on contact with said suspension: c) contactine the catalytic paste coming from step b) with an organo-ahrminum compound in the presence of an inert hydrocarbon, optionally an electron donor compound, at a temperature from 5°C to 30CC: d) polymerizing one or more a-olefins of formula CH2=CHR. where R is hydrogen or a hydrocarbon radical having 1-12 carbon atoms, in one or more 19. The process according to claim 16. wherein said inen hydrocarbon of step c) is a C3-C6 alkane. 20. The process according to claim 16, wherein the catalyst withdrawn from step c) is subjected to prepolymerization in a loop reactor before the feeding to step d). Dated this 24 dzy of February' 2009 {ARINDAM PAUL) OfCA>nTO^LL&CO. Agent for the Applicants

Full Text

The present invention relates to a method for preparing a catalytic composition in the form of cataiyric panicles dispersed in a semi-fluid matrix, the catalytic composition Demg suitable to be transferred and fed into a reactor for the olefin polymerization. The present invention also relates to a process for the polymerization of olefins carried out in the presence of a polymerization catalyst comprising a solid catalytic component dispersed in a semi-fluid matrix.
It is widely known in the art that catalytic components of the Ziegler/Natta type comprising a titanium compound supported on magnesium chloride show a high activity in the polymerization of olefins. These catalytic components are indeed the most extensively used in the polymerization of olefins such as ethylene, propylene, etc. and are obtained in a powder form by reacting a titanium compound comprising at least a titanium-halogen bond with a solid support comprising a magnesium halidc. In a continuous process for the olefin polymerization it is largely felt the need of continuously feeding the catalyst particles at a constant flow rate to the polymerization reactor, Furthermore, the solid catalytic components have to be transferred to the polymerization reactor without a significant modification of their morphology and other physical properties, such as porosity, surface area, etc., also trying to achieve a homogeneous distribution diereof inside the gas or liquid medium used as the carrier. A method of transferrina the solid catalyst particles to die pohTnerizarion apparatus consists in forming a suspension of the catalytic particles in a liquid hydrocarbon and then snecessivery pumping die obtained suspension into the pressurized reaction system. However, this method does not allow an accurate dosage of the catalyst panicles in the porymerizarioii apparams and moreover, it may cause the breaking of some catalytic particles, either during me stirring of the suspension, or during the subsequent pumping. The breaking of mc catalyst with consequent formation of particles of reduced size (fines) is particularly detrimental, since the catalyst particles must have a predetermined morphology, which is strictly conelated to the morphology of the polymer targeted to be prepared.

In order to facilitate hs dosage and transfer, die catalyst powder can be combined with a wax. which makes rt possible continuously feeding a waxed catalyst into the polyinerizarion rcacEs-. By way of example, reference is made to US 4,158,571 and US 4.182,817 disclosing a method for feeding solid catalyst particles to a polymerization reaction system. These patents teach the preparation of a semi-solid paste containing dispersions of at least one functional material, such as a polymerization catalyst, uniformly dispersed throughout a continuous solid phase. Said continuous solid phase has tbe theological features of a Bingham fluid and consists essenrialiy of an intimate mixture of a wax and a liquid hydrocarbon. The preparation of this catalytic paste comprises a first step of heating and mixing together the desired proportions of a molten wax and a liquid hydrocarbon in stirred vessel, and successive step involving the addition of the finely-divided solid catalyst to the above obtained mixture. The mixture is agitated with sufficient intensity to disperse the finely-divided solid catalyst uniformly throughout the melt, after which the entire composition is cooled until it solidifies. Preferred waxes used in the above preparation method are petroleum waxes. Notwithstanding die obtained composition is useful to achieve an accurate dosage and transfer of the dispersed catalyst to the polymerization apparatus, the method described in US 4.158.571 and US 4,182.817 is such that little amounts of wax can easily penetrate inside tbe pores and on the surface of the catalyst particles: as a consequence, the obtained eaiafyrk paste shows drawbacks in the successive step of activation with organo^umimrni compounds and also in case of prepolymerization (T=20-30°C), since tne occfasJoc even partial, of tiie catalyst pore and surface caused by zhs sotiuificaiioa of me was generates problems in achieving a satisfying activation of the catalytic sites, which leads TO a low catalyst activity in polymerization.
Other drawbacks are correlated with the preparation of a semi-solid catalytic paste. For instance, the method described in US 4,898,847 uses a paraffmic hydrocarbon with a melting point 5O-70DC or an atactic polypropylene, which is deposited on a supported catalyst suspended in hydrocarbon solvent. Successively, according to the description of this patent, it is advantageous to remove said hydrocarbon solvent, for instance, by decantation or by evaporation with stirring, in order to achieve an uniform coating of the supported catalyst with the above paraffmic hydrocarbon. This additional step of

WO 00/47638 relates to a polymerization catalyst system obtained by a process comprising a first activation step, wherein a solid transition metal compound is contacted whh a first orgaiKKaiuminiim compound in the presence of a oil to give a first reaction mixture, and a second activation step including the contact of said first reaction mixture with a second organo-aluminum compound According to an alternative embodiment, the first activation step can be carried out in the presence of an oil mixed together with a component selected from a wax, fat or solid paraffin. The aim of the process described in WO 00/47638 is to reach a mild activation of the solid transition metal compound by means of the organo-aluminum compound. By adding some oil to the first activation step a smooth, suppressed reaction between the solid transition metal compound and the first organo-aluminum compound is accomplished. The description of WO 00/47638 refers to the step of preactivaring the catalyst components in the presence of oil and a wax/paraffin: this patent fails to provide an useful teaching on how to preserve the catalyst morphology in the line connecting the catalyst powder storage and the polymerization reactor.
It would be largely desirable to overcome the above drawbacks correlated with the prior art methods to prepare a catalytic paste, providing an alternative preparation method able to preserve me catalyst morphology throughout me line connecting the catalyst powder storage and me polymerization reactor.
The Applicant has now foetid diai a continuous dosage and transfer of solid catalyst particles to a porymerization reactor can be successfully performed without substantially altering their morphology and porosity by the incorporation of the catalyst particles in a suitable serm-fhrid matrix-It is therefore a first object of the present invention a method for preparing a catalytic composition for the olefin polymerization in the form of a dispersion of catalyst particles in a semi-fluid matrix, characterized in that it comprises the steps of: a) forming a suspension of catalyst particles in oil by loading under a continuous stirring dry catalyst powder into a tank containing said oil. the load velocity of the catalyst powder per m" of oil interface being less of 800 kg/h*m";

bi adding under stirring a moiisE thickening agent having a melting point in a
range from 50 tc ~0"C. while maintaining the catalyst suspension in oil at a
TcmperaiurE such, thai said thickening agent solidifies on contact with said
suspension.
According to the invention, "oil interface" is intended as the surface separating the
liquid oily phase from the above gaseous phase in the tank of step a), while maintaining
the oil in a motionless condition. In case of a common tank with a circular cross section,
the oil interface is therefore given by me area of die circle having me internal diameter
of me tank as its diameter.
According to the method of the invention, a mixing tank is first filled with oil. Being the catalyst extremely sensitive to oxygen and moisture, the oil fed to the mixing tank is degassed by storage under inert atmosphere and dried by a nitrogen flow: this removes traces of humidity and oxygen.
The catalyst powder is stored inside a drum under an inert atmosphere and from this drum the catalyst is discharged and loaded into the tank containing the oil. According to a preferred embodiment of the invention, the solid catalyst particles introduced into the tank containing oil of step a) are Ziegler-Natta catalytic components based on a titanium halide, preferably TiCU, supported on magnesium halide. Oil and thickening agents used in the present invention are necessarily inert compounds towards the catalyst system, dial is ro say oil and tfiickening agents cannot react with the catalyst components, snch as the solid component the donor compounds and the

The catalyst powder is added slowly to the oil in order to promote me immediate dispersion of die catalyst in oil and. above all. to avoid accumulations of solid catalyst on the oil upper surface, h has been observed that a high load velocity of the catalyst is detrimental in achieving an acceptable dispersion of catalyst particles in die oil. since it causes the agglomeration of the solid particles with formation of many lumps, not easily dispcrsible in the oil. Therefore, in step a) the catalyst load velocity per m" of oil interface is generally kept at a value of less than 800 kg/h-m2. preferably in a range from 200 to 500 ka/h.ml

The above load velocity of the cs:a;ysi powder may be adjiisted by means of a funnei-
shape discharge 21 the botton* of me drum co-taming the catalyst powder. According to
a preferred embodiment of me invention, the above load velocity of the catalyst is
adjusted by means of an L-varvc, in which the flow rate of catalyst entering the mixing
tank of step a> is kept at the desired vaiue by means of regulation of a nitrogen flow.
The formation of the suspension of catalyst in oil (step a) is generally carried out under
continuous stirring by keeping the temperature above 50°C, preferably in a range from
from 60 to 90CC under an inert atmosphere. The feeding of oil and catalyst to step a) is
such to form a suspension of catalyst particles in oil with a solid concentration ranging
from 80 gl to 500 g1, preferably 150-350 g/1.
The stirring intensity of the suspension is preferably the minimum necessary to avoid
me settling of the catalyst powder. The peripheral velocity of the stirring device is
generally maintained at a value lower than 0.7 m/s, preferably comprised between 0.4
and 0.6 m/s.
Oil is defined as a hydrocarbon or hydrocarbons mixture, which is liquid at room
temperature and with a relatively low vapor pressure. The oil used for preparing the
catalyst suspension of step a) can be selected from mineral oils, synthetic oils, with the
proviso of being inert towards the catalyst components.
Preferred mineral oils are paxaffmic white oils and. among these, vaseline oils. White
oils are colorless, odorless, tasteless mixtures of saturated paraffinic and naphthenic
hydrocarbons. These nearly chemically inert oils are virtually free of nitrogen, sulfur.
oxygen and aromatic hydrocarbons. Suitable white oils are OB22 AT. Wiuog 70. Fina
Vestan A 360B and Shell Ondma 64.
Synthetic oils can be obtained, for instance, by the oligomerization of decene,
fractionating the product to an average of 30 carbon atoms and successive
hydrogenation.
It has been observed that a low viscosity of the oil contributes to maintain unchanged
the particle size distribution of the catalytic particles during step a) and b) of the present
invention. As a consequence, the dynamic viscosity of the oil at 20CC is preferably
comprised between 10 and 400 cPs, more preferably between 20 and 200 cPs.

stirring for a rime preferably comprised between 30 minutes and 3 hours, in order to
assure a complete weeing and dispersion of the catalyst particles. In the case the
catalytic component contains a high amount of volatile compounds, step a) may be
favorably carried out under vacuum.
Once prepared, the oil-catalyst suspension is preferably cooled at a temperature
generally comprised between 2 and 25CC, before adding the molten thickening agent of
step b), this component being previously degassed by storage under inert atmosphere to
eliminate traces of humidity and oxygen.
The thickening agent used in the present invention is a solid or semi-solid substance at
room temperature, having a melting point in the range from 30 and 70°C. Suitable
compounds are selected from petrolatum and waxes with a melting point in the range
from 30 and 70CC.
Petrolatum is a natural mixture of microcrystallinc wax and oiL, obtained by fractional
distillation of petroleum, as the byproduct of the heaviest lubricating oil fraction. When
fully refined it becomes microcrystaliine wax.
The preferred waxes used in the present invention are paraffin waxes, in particular
vaseline (commonly named also "vaseline grease"). Paraffin waxes contain Ci^-C-=

The method of the invention preferably uses molten vaseline as the thickening agent of step b>. Said component is fed into the tank containing the suspension of catalyst in oil at a feeding temperature in a range from 75= to 110°C preferably from. 85 to 105°C. The molten thickening agent is slowly fed while stirring the oil'catalyst mixture with a peripheral speed of the stirring device as mentioned for step a). Due to the low temperature of the catalyst suspension, the molten thickening agent solidifies almost instantaneously in flaky particles which disperse in the oil, further lubricating the overall system. The thermal capacity of the suspension is sufficient to ensure the

instantaneous solidification of the thickening agent during its progressive feeding into
*e sispessioTL To sins ais it is preferable to refrigerate the suspension of catalyst in oil
during step b) to maintain its Temperature in a range comprised between 2"C and 25'JC,
mus avoiding 233- increase of temperature which would hinder a prompt solidification of
me ririckening agent. At the end of the addition of the thickening agent, a semi-solid
catalytic paste is obtained in which no phase separation (oil phase or solid phase) is
observed-
The amount of mohen dnckening agent added during step b) is sufficient to form a
stable semi-fluid matrix, in which the catalyst particles remain suspended. The weight
ratio of thickening agent with reference to the total amount of oil and thickening agent
is generally comprised between 0.35 and 0.5, with concentrations of catalyst in the
catalytic paste between 50 and 500 g/1. Preferably, said weight ratio is comprised
between 0.3 and 0.4, with catalyst concentrations between 200 and 300 g/1. Is is clear
Shat lower catalyst concentrations imply a higher weight ratio of thickening agent, since
the catalyst itself acts as a thickener.
At the end of the addition of the thickening agent, the semifluid catalytic paste is further
cooled, always under stirring, to a temperature generally lower than 25=C, preferably
comprised between 0DC and 15°C. In these conditions the catalytic composition may be
transferred in metering syringes suitable to allow the feeding of the catalyst to the
reaction system wim an accurately controlled flow rate.
The method according to me present invention allows prepare a semi-fluid catalytic
paste with many correiaied technical advantages.
Step a) of the invention is carried out with specific operative conditions, so as to assure
a complete wetting of the catalyst particles, including the particle pores, so that the
imerposttion of an oil layer hinders an accidental direct friction between the catalyst
particles. This contributes to preserve the morphologic properties of the catalytic
particles during the preparation of the catalytic composition, avoiding an undesired
formation of excessively low size particles of polymer (fines) during the successive
prepolymcrization and polymerization of alpha-olefins.
Moreover, the addition of a thickening agent during step b) does not affect the surface
and pores of the catalyst particles. The latter are therefore separated from the

oiithickrening agent mams by an oii layer. which is easily and quickly removable in the
successive steps of catalyst activation, nrepoiyraerizarion and polymerization.
Other advantages and features of die present invention arc illustrated in the following
detailed description with reference to me attached drawing, which is representative and
not iimkathe of the scope of the invention.
Figure ! shows a preferred embodiment to carry out the present invention, wherein a L-
valve is used to adjust the load velocity of the catalyst powder in step a).
Also me devices and lines suitable to convey the catalytic composition of the invention
up to the polymerization reactor are schematically shown in Fig.I, as well as the steps
of catalyst activation and prcpolymerization.
With reference to Figure 1, a solid catalytic component is stored in the form of a dry
powder inside the drum 1, while the vessel 2 contains oil and the vessel 3 contains the
thickening agent (TA).
A tank 4 endowed with a stirring device 5 is used to prepare the catalyst suspension of
step a). The tank 4 is first filled with the oil coming from the vessel 2 via line 6.
Afterwards the catalyst particles are discharged from die drum 1 via line 7 and enter a
L-valve 8, which is used for adjusting the velocity of catalyst load into the mixing tank
4. The flow rate of catalyst powder introduced into the mixing tank 4 is kept at the
desired value by a control valve 9 adjusting a stream of nitrogen which enters the L-
valve 8 via line 10.
When die feeding of the catalyst powder in the tank 4 is completed, the mixture is
mainained under stirring ibr the schabie rime io order to assure a complete » etting and
dispersion of me catalyst particles in me oil. Once prepared, the oil/catalyst suspension
is successively cooled, and men me molten thickening agent coming from the vessel 3 is
fed into the tank 4 via line 11. The molten thickening agent is slowly fed, while
continuously stirring the oil/catalyst mixture inside the tank 4. Due to the low
temperature of the catalyst suspension, the molten thickening agent solidifies almost
instantaneously in flaky particles which disperse in the oil.
When the feeding of the thickening agent is completed, a stable semi-solid catalytic
paste is obtained in which no phase separation (oil phase or solid phase) is observed: the
catalyst particles remain suspended in the semi-solid paste. The catalytic paste is then

As shown m Fig.l the catalytic paste is withdrawn from the mixing tank 4 avoiding the
use ot a discharge varvc, e.g. 3 bail valve, bur using a device capabic of withdrawing the
dispersion of catalyst in tha semi-solid matrix without rough movements. A dosing
syringe 12 is used for softly withdrawing the catalyst paste from the tank 4 and softly
pushing it into line 13a and 13b. Moreover, a couple of two dosing syringes 14 and 15 is
exploited for ensuring a continuous and delicate metering of catalytic paste to the
successive step of catalyst activation. While the syringe 14 is filled with catalytic paste
coming from line 13a, the second syringe 15 pushes and transfers the catalytic paste to
line 16. Likewise, when the syringe 15 is filled with catalytic paste coming from line
13b, the first syringe 14 pushes and transfers the catalytic paste to line 16 and
consequently to the activation vessel 17.
An organo-aluminum compound as the catalyst activator is fed via Sine 18 to the
activation vessel 17. Also a hydrocarbon solvent such as propane, is conveniently fed to
the activation vessel 17 via line 19, optionally together with an electron donor
compound.
The activated catalyst system is hence discharged from the activation vessel 17 and fed
via line 20 to a loop reactor 2 J used to carry out the prepolymerization of the catalyst.
Line 20 merges into an olefin pick-up 22. which is the feeding line of the olefin to the
loop reactor 21. The prepofyTnerized catalyst system is successively fed via line 23 to
the polymerization reactor (not shown).
As explained in connection with Fig. 1, the semi-fluid catalytic paste prepared by means
of me method of the invention is particularly suitable to be transferred and treated in
one or more successive steps in order to have a controlled flow rate of catalyst system
introduced into the polymerization reactor.
It is therefore a second object of me invention a process for the polymerizarion of
olefins carried out in the presence of a solid polymerization catalyst, the process being
characterized in that said solid polymerization catalyst is treated and transferred to the
polymerization reactor by the following steps:
a) forming a suspension of catalyst particles in oil by loading under a continuous

As explained, method of the present invention implies that the presence of the thickening agent is confined to the semi-solid matrix, which maintains the catalyst particles in a stable dispersion. Different from the catalytic pastes described in the prior an patents, the thickening agent docs not penetrate inside the pores and on the surface of die catalytic particles: this makes the catalyst particles to be efficiently activated by means of the contact with an organo-aluminum compound able to reach the catalytic sites inside the particles pores. Moreover, the catalyst particles enter the reaction system

The analysis comprises the addition of the sample, under nitrogen flow, to a measure cell containing hexane and provided with a stirrer and with a circulation pump having a flow rate comprised between 70 and 100 1/h. The measure is performed while the suspension is circulated. The central process unity of the analyzer processes the

obtained from the bottom discharge of the stirred tank, were added to 50 cm" of hcxanc, and die stirred suspension in hcxanc was analyzed.

A slurry of polypropylene in propylene was continuously discharged from the loop

reactor and was subjected to healing in a jacketed pipe up to the temperature of &5CC
before entering a flash drum, wherein the monomer evaporation and the polymer
separation from the slurry were performed.
Tne catalyst mileage was of -^OKg of porymer per g of catalyst and the obtained
po.Vpropyiene had a Men Index MIL of 66 g'10\ as indicated in Table 2.
A sample of the obtained polymer was dried at 70°C. under nitrogen flow for 3 hours,
and then subjected to PSD analysis: spherical particles of polypropylene with an
average diameter from 0.1 mm to 4 mm and an amount of fines (diameter 0.4% by weight were obtained.
Example 2A - Preparation of the catalytic paste
- STEP A) -
White oil Winog 70 (supplier Tudapetrol) having a dynamic viscosity of 8.5 cPs at
100°C was used in this example.
The same stirred tank of Example 1A was used for preparing the catalytic paste
according to the method of the invention. 165.7 Kg of white oil Winog 70 were charged
in the stirred tank at room temperature. The oil temperature was then increased up to
reach the value of 70CC inside the stirred tank, while continuously stirring at a stirring
velocity of 15 rpm.
Successively 85 Kg of dry catalyst: powder were loaded to the stirred tank in a time of
20 minutes. Takmg into account that the oil interface area was about 0 J m\ the catalyst
load velocity per m" of oil interface was equal to 510 Kg'nrh, that is to say a value
according to me r^a-.-rrnc of me pressnr invention.
At me end of the catalyst load, the catalyst suspension was continuously subjected to
stirring at 15 rpm for U hour mamrammg the temperature at 70=C. Afterwards, the
catalyst suspension was cooled to 20CC by circulation of cooling water in the external
jacket of the stirred tank.
- STEP B) -
71 Kg of molten Vaseline Pionier 17122 (supplier Tudapetrol) were fed to the tank containing the catalyst suspension at a feeding temperature of 90°C. The addition of the molten vaseline was carried out from the top of the tank, while maintaining the tank under stirring at 15 rpm. At the end of the addition of the molten vaseline, the

The catalytic paste was withdrawn by the stirred tank by a dosing syringe and then continuosly transferred by means of two dosing syringes to a catalyst activation vessel. Triethylaiuminium (TEAL) as the cocatajyst, and cyclohexylmethyldimethoxysilane (CHMMS) as an external donor were introduced into the activation vessel, with a weight ratio TEAL-Ysolid catalyst) of 10.5 and a weight ratio TEAL/CHMMS of 25. Propane as a diluent was also fed to the catalyst activation vessel. The above components were pre-contacted in the activation vessel at a temperature of 10CC for 20 minutes.

Propylene was polymerized in the loop reactor using Hj as the molecular weight regulator. Ethylene was also fed to die loop reactor in an amount of 0.3% by moL Make-up propylene and hydrogen as molecular weight regulator were continuously fed to the loop reactor. The polymerization of propylene was carried out at a temperature of 70°C and at a pressure of 3.4 MPa. A slurry of polypropylene in propylene was continuously discharged from the loop

543 Kg of molten vaseline BF were fed to the tank containing the catalyst suspension at a feeding temperature of 90=C. The addition of the molten vaseline was carried out from the top of the tank, while maintaining the tank under stirring at 15 rpm. At the end of the addition of the molten vaseline, the temperature of the catalytic paste was decreased to

regulator were fed to the recycle gas line of the reactor. The polymerization of
propylene was carried out at a temperature of 80°C and at a pressure of 2.0 MPa.
The catalyst mileage was of 20Kg of polymer per g of catalyst. It can be seen from

Triethylalinnmium (TEAL) as the cocatalyst and cyclohexylmerhyldimcthoxysilanc (CHMMS) as an external donor were fed to the activation vessel. The same operative conditions of Example IB were performed.

- Polymerization -
The prepolymerized catalyst was discharged from the loop prepotymerizator and was
continuously fed to a liquid loop reactor together with propylene as the monomer and
hydrogen as the molecular weight regulator. The polymerization of propylene was
carried out according to the same operative conditions of Example IB (T=70°C, p=3.4
MPa).
A slurry of polypropylene in propylene was continuously discharged from the loop
reactor and was subjected to heating in a jacketed pipe up to the temperature of 85DC
before entering a flash drum, wherein the monomer evaporation and the polymer
separation from the slurry were performed.
The catalyst mileage was of 40K_g of polymer per g of catalyst and the obtained
polypropylene had a Melt Index MIL of 68 g/10'. as indicated in Table 2.
A sample of the obtained polymer was dried at 70CC, under nitrogen flow for 3 hours,
and then subjected to PSD analysis: spherical particles of polypropylene with an

Successively 40 Kg of dry catalyst powder obtained by the above described procedure were loaded to the stirred tank in a time of 4 minutes. Taking into account mat me oil interface area was about 0.5 m2, the catalyst load velocity per m2 of oil interface was equal to 1200 Kg'm2h, outside the range claimed in the present invention.

-STEPB)-
25.6 Kg of molten vaseline BF were fed to the tank containing the catalyst suspension at a feeding temperature of 95:C. The addition of the molten vaseline was carried out from me top of the tank, while maintaining the tank under stirring at 15 rpm. At the end of the addition of the mohsn vaseline, the temperature of the catalytic paste was decreased to I0°C: at this temperature, the catalytic paste containing about 300 Kg/m3 of solid catalyst powder, was still sufficiently fluid to be discharged from the stirred tank by means of a dosing syringe.
The particle size distribution (PSD) analysis of the catalyst powder suspended in the semi-fluid catalytic paste was performed. The granulometric distribution of the catalyst in the catalytic paste gave a negative result showing a high amount of fine particles: owing to particles breakage during the preparation of the paste the fraction having d

CLAIMS:

conriniious stirring dry catalyst powder into a tank containing said oil. the load velocity of die catalyst powder perm2 of oil interface being less of 800 kg/h*m2; b) adding under stirring a molten thickening agent having a melting point in a range from 30 to 70:C. while maintaining the catalyst suspension in oil at a temperature such that said thickening agent solidifies on contact with said suspension.
2. The method according to claim 1, wherein the load velocity of catalyst powder
in step a) is comprised in a range from 200 to 500 kg/h-m2.
3. The method according to claim 1, wherein said load velocity in step a) is
adjusted by means of an L-varve.
4. The method according to any of claims 1-3, wherein the formation of said suspension of catalyst in oil in step a) is carried out under continuous stirring by keeping the temperature in a range from 60 to 90=C under an inert atmosphere.
5. The method according to claim 1. wherein in step a) a suspension of catalyst particles in oil whh a solid cracenrrarion ranging from 80 gl to 500 gl is

mineral oils, synthetic oOs. The method according H) claim 6. wherein said oil is a paraffinjc white oiL
8. The method according to claims 6-7. wherein said oil has a dynamic viscosity at
I00°C comprised between 1 and 12 centiPoise (cPs).
9. The method according to claim I, wherein said catalyst particles introduced into
uie rank of step a) are Ziegier-Nana catalytic components based on a titanium
halide supported on magnesium halide.

13. The method according to any of claims 1-12, wherein said temperature at which mc catalyst suspension in oil is kept during step b) ranges from 2°C to 25°C.
14. The method according to claim 1. wherein the weight ratio between said thickening agent and the total amount of oil and thickening agent is comprised between 0.15 and 0.5.
15. The method according to any of claims 1-14, wherein a catalytic paste with
catalyst concentrations between 50 and 500 gl is obtained from step b).
16. A process for the polymerization of olefins carried out in the presence of a solid
polymerization catalyst ihe process being characterized in that said solid
polymerization catalyst is treated and transferred to the polymerization reactor by
the following steps:

b) adding under storing a mohsn thickening agent having a melting point in a range from 30 ro 70C. while maintaining rhe catalyst suspension in oil at a temperature such thai said thickening agent solidifies on contact with said suspension:
c) contactine the catalytic paste coming from step b) with an organo-ahrminum compound in the presence of an inert hydrocarbon, optionally an electron donor compound, at a temperature from 5°C to 30CC:
d) polymerizing one or more a-olefins of formula CH2=CHR. where R is hydrogen or a hydrocarbon radical having 1-12 carbon atoms, in one or more

19. The process according to claim 16. wherein said inen hydrocarbon of step c) is a
C3-C6 alkane.
20. The process according to claim 16, wherein the catalyst withdrawn from step c)
is subjected to prepolymerization in a loop reactor before the feeding to step d).
Dated this 24 dzy of February' 2009
{ARINDAM PAUL) OfCA>nTO^LL&CO. Agent for the Applicants

Documents:

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Patent Number

278239

Indian Patent Application Number

1043/CHENP/2009

PG Journal Number

53/2016

Publication Date

23-Dec-2016

Grant Date

19-Dec-2016

Date of Filing

24-Feb-2009

Name of Patentee

BASELL POLIOLEFINE ITALIA S.R.L

Applicant Address

VIA PERGOLESI, 25, 20124 MILANO

Inventors:

#	Inventor's Name	Inventor's Address
1	FAIT, ANNA	VIA PALESTRO, 101, I-44100 FERRARA
2	PATRONCINI, GIOVANNI	VIA COMACCHIO, 58, 44100 FERRARA
3	PEDRIALI, LORELLA	VIA MENTANA, 17 MONTESANTO, 44010 FERRARA
4	FLAMMINI, ROBERTO	P.LE SAN BENEDETTO, 5, 44100 FERRARA
5	BENETTI, DERENZIO	VIA DANTE ALIGHIERI, 55/A COPPARO, 44034 FERRARA

PCT International Classification Number

C08F10/00

PCT International Application Number

PCT/EP07/58087

PCT International Filing date

2007-08-03

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	06119571.5	2006-08-25	EUROPEAN UNION