Solid catalyst component and process for the (co) polymerization of ethylene

Abstract

Catalyst and solid component of catalyst for the (co)polymerization of ethylene, comprising titanium, magnesium, chlorine, a protic organo-oxygenated compound D p and a neutral aprotic electron-donor compound D, in the following molar ranges: Mg/Ti=1.0-50; D/Ti=1.0-15; Cl/Ti=6.0-100; D p /D=0.05-3; and a process for obtaining said component comprising the following steps in succession: (a) formation of a mixture and dissolution, in said electron-donor aprotic compound D, of a magnesium chloride and a titanium compound having formula (II): Ti v (OR 3 ) a X (v-a) wherein each R 3 independently represents a hydrocarbyl or acyl radical having from 1 to 15 carbon atoms; each X is selected from chlorine, bromine or iodine; “v” has the value of 3 or 4, and “a” is a number varying from 0 to “v”, with a molar ratio between titanium and magnesium ranging from 1/1 to 50/1; (b) partial separation of the compound D from said mixture prepared in step (a) until a residue is obtained, solid at room temperature, wherein the D/Ti ratio ranges from 1.5 to 40, (c) formation of a suspension of said solid organo-oxygenated protic compound D p , in such a quantity that the molar ratio D p /D ranges from 0.1 to 1.2 and maintaining the mixture until equilibrium is reached, to form the desired solid component of catalyst.

1 . A solid component of catalyst for the (co)polymerization of ethylene, comprising titanium, magnesium, chlorine, an organo-oxygenated protic compound D p , and a neutral electron-donor aprotic compound D, in the following molar ratio ranges: 
 Mg/Ti=1.0-50; D/Ti=1.0-15;    Cl/Ti=6.0-100; D p /D=0.05-3.    
   
   
       2 . The solid component according to  claim 1 , additionally comprising an inert solid I in a suitable granular form, in a quantity ranging from 10 to 90% by weight with respect to the total weight of the solid component.  
   
   
       3 . The solid component according to  claim 2 , wherein said inert solid I is in a quantity ranging from 25 to 50% by weight.  
   
   
       4 . The solid component according to any of the previous claims, wherein said inert solid I is selected from granular inorganic solids included in the group: silica, titania, silico-aluminates, calcium carbonate, magnesium chloride, having average dimensions of the granule ranging from 10 μm to 300 μm.  
   
   
       5 . The solid component according to  claim 4 , wherein said solid I consists of microspheroidal silica having an average diameter ranging from 20 to 100 μm, a BET surface area ranging from 150 to 400 m 2 /g, a total porosity equal or higher than 80% and an average pore radius of 50 to 200 Å.  
   
   
       6 . The solid component according to any of the previous claims, characterized by the following molar ratio ranges among the constituents: 
 Mg/Ti=1.5-10; D/Ti=3.0-8.0;    Cl/Ti=10-25; D p /D=0.1-2.0.    
   
   
       7 . The solid component according to any of the previous claims, wherein said ratio D p /D ranges from 0.2 to 1.0  
   
   
       8 . The solid component according to any of the previous claims, wherein said organo-oxygenated protic compound D p  is selected from compounds having the following formula (II):  
       R-(A) m -OH  (II)  
     wherein: 
 R is an aliphatic, cyclo-aliphatic or aromatic radical, optionally fluorinated, containing from 1 to 30 carbon atoms,  
 A is selected from divalent groups having the formula CR 1 R 2 , CO, SCO and SO, preferably CO or CR 1 R 2 , wherein each R 1  and R 2  is independently hydrogen or an aliphatic or aromatic group having from 1 to 10 carbon atoms;  
 m is 0 or 1.  
 
   
   
       9 . The solid component according to any of the previous claims, wherein said organo-oxygenated protic compound D p  is selected from aliphatic or aromatic, preferably aliphatic, alcohols and organic acids, having from 2 to 10 carbon atoms.  
   
   
       10 . The solid component according to any of the previous claims, wherein said aprotic electron-donor compound D is a coordinating organic compound having from 3 to 20 carbon atoms, comprising at least one heteroatom selected from non-metallic compounds of groups 15 and 16, preferably at least one oxygen atom linked to a carbon atom.  
   
   
       11 . The solid component according to any of the previous claims, wherein said electron-donor compound D is selected from compounds of the groups of ketones, ethers, esters, amines, amides, thioethers, and xanthates, linear or cyclic, aliphatic or aromatic, having from 4 to 10 carbon atoms.  
   
   
       12 . The solid component according to any of the previous claims  10  or  11 , wherein said compound D is selected from dibutyl ether, dihexyl ether, methylethyl ketone, diisobutyl ketone, tetrahydrofuran, dioxane, ethyl acetate, butyrolactone, preferably tetrahydrofuran.  
   
   
       13 . The solid component according to any of the previous claims, wherein said titanium is present in a quantity ranging from 1 to 10% by weight.  
   
   
       14 . A process for the preparation of a solid component according to any of the previous claims from  1  to  13 , comprising the following steps in succession: 
 (a) formation of a mixture and dissolution, in aprotic electron-donor compound D, of a magnesium chloride and a titanium compound having formula (I):      Ti v (OR 3 ) a X (v-a)   (I)    wherein each R 3  represents a hydrocarbyl or acyl radical having from 1 to 15 carbon atoms;    each X is selected from chlorine, bromine or iodine;    v is 3 or 4, and represents the oxidation state of titanium,    a is a number ranging from 0 to v,    with a molar ratio between magnesium and titanium ranging from 1/1 to 50/1;    (b) partial separation of the compound D from said mixture prepared in step (a) until a residue is obtained, solid at room temperature, wherein the D/Ti ratio ranges from 1.5 to 40,    (c) formation of a suspension of said solid residue in a liquid hydrocarbon medium,    (d) addition to said suspension of an organo-oxygenated protic compound D p , in such a quantity that the molar ratio D p /D ranges from 0.1 to 1.2 and maintaining the mixture until the desired solid component of catalyst is formed.    
   
   
       15 . The process according to  claim 14 , wherein, in step (a) an inert solid I in a suitable granular form, is also added.  
   
   
       16 . The process according to the previous  claim 15 , wherein said inert solid I is selected from granular inorganic solids included in the group: silica, titania, silico-aluminates, calcium carbonate, magnesium chloride, having average granule dimensions ranging from 10 μm to 300 μm.  
   
   
       17 . The process according to the previous claims  15  or  16 , wherein said inert solid I consists of microspheroidal silica having an average diameter ranging from 20 to 100 μm, a BET surface area ranging from 150 to 400 m 2 /g, a total porosity equal or higher than 80% and an average pore radius of 50 to 200 Å.  
   
   
       18 . The process according to any of the previous claims from  14  to  17 , wherein said titanium compound having formula (I) is essentially soluble in said compound D and is selected from titanium chlorides, bromides, alcoholates and carboxylates.  
   
   
       19 . The process according to any of the previous claims from  14  to  17 , wherein said compound having formula (I) in step (a) is titanium trichloride.  
   
   
       20 . The process according to any of the previous claims from  14  to  19 , wherein said magnesium chloride is in amorphous or semi-amorphous form.  
   
   
       21 . The process according to any of the previous claims from  14  to  20 , wherein, in said step (a), the atomic ratio between magnesium and titanium ranges from 1.0 to 50 and the ratio (D moles)/(Ti atoms) ranges from 5 to 100.  
   
   
       22 . The process according to any of the previous claims from  14  to  21 , wherein said step (a) is carried out at a temperature ranging from room temperature to the boiling point of the donor compound D, for a time varying from a few minutes to 24 hours, until at least 80% of said compounds of Ti and Mg have been dissolved.  
   
   
       23 . The process according to any of the previous claims from  14  to  22 , wherein said step (b) is carried out by means of evaporation, preferably by spray-drying.  
   
   
       24 . The process according to any of the previous claims from  14  to  23 , wherein the molar ratio D p /D in said step (d) ranges from 0.2 to 1.2.  
   
   
       25 . The process according to any of the previous claims from  14  to  24 , wherein said step (d) is carried out by heating the mixture to a temperature ranging from 40 to 100° C., for a period of time varying from 5 minutes to 5 hours.  
   
   
       26 . The process according to  claim 25 , wherein the reaction mixture in said step (d) is heated to a temperature of 60 to 80° C., for a period ranging from 5 to 60 minutes.  
   
   
       27 . A process for the preparation of a solid component according to any of the previous claims from  1  to  13 , comprising the reaction in an inert liquid medium of a solid precursor containing titanium, magnesium, chlorine, an aprotic electron-donor compound D and optionally an inert solid compound I, in the following molar ratios between each other: 
 Mg/Ti=1-50; D/Ti=2.0-20; Cl/Ti=6-100    and wherein said inert solid I is in a quantity ranging from 0 to 95%,    with protic organo-oxygenated compound D p , in such a quantity that the molar ratio D p /D ranges from 0.1 to 1.2, until equilibrium is reached.    
   
   
       28 . The process according to  claim 27 , wherein said solid precursor is characterized by the following ratios: 
 Mg/Ti=1.5-10; D/Ti=4.0-12; Cl/Ti=10-30 and said inert solid I is in a quantity ranging from 20 to 60% by weight with respect to the total weight of the precursor.    
   
   
       29 . The process according to any of the previous claims  27  and  28 , wherein the molar ratio D p /D in said step ranges from 0.2 to 1.2.  
   
   
       30 . The process according to any of the previous claims from  27  to  29 , wherein said reaction is carried out at a temperature ranging from 40 to 100° C., for a period varying from 5 minutes to 5 hours.  
   
   
       31 . The process according to the previous  claim 30 , wherein said reaction is carried out at a temperature ranging from 60 to 80° C., for a period of 5 to 60 minutes.  
   
   
       32 . A catalyst for the (co)polymerization of ethylene, which is obtained by means of contact and reaction of said solid component according to any of the previous claims from  1  to  13 , with a co-catalyst comprising a hydrocarbyl compound of a metal selected from Al, Ga, Mg, Zn and Li.  
   
   
       33 . The catalyst according to  claim 32 , wherein the atomic ratio between the metal in the co-catalyst and titanium in the solid component of catalyst ranges from 10:1 to 500:1 and preferably from 50:1 to 200:1.  
   
   
       34 . The catalyst according to  claim 32  or  33 , comprising titanium, magnesium, aluminum and chlorine, wherein said co-catalyst comprises an alkylic organometallic compound of aluminum.  
   
   
       35 . The catalyst according to  claim 34 , wherein said organometallic compound of aluminum is selected from aluminum tri-alkyls containing from 1 to 10 carbon atoms in each alkyl group.  
   
   
       36 . The catalyst according to any of the claims from  32  to  35 , wherein the contact between the solid component and co-catalyst is obtained in situ in the polymerization reactor.  
   
   
       37 . The catalyst according to any of the claims from  32  to  36 , wherein said solid component is activated before contact with said co-catalyst, by reaction with an aluminum alkyl or alkyl chloride represented by the following general formula (III):  
       AlR′ n X (3-n)   (III)  wherein: R′ is a linear or branched alkyl radical containing from 1 to 20 carbon atoms, X is selected from H and Cl, preferably Cl, and “n” is a decimal number having values ranging from 1 to 3, preferably from 2 to 3;    in such a quantity that the Al/(D+D p ) ratio between the aluminium moles in said compound having formula (III) and the total of D and D p  moles in said solid component, ranges from 0.1 to 1.5.    
   
   
       38 . The catalyst according to  claim 37 , wherein said R′ in formula (III) is a linear or branched aliphatic radical, having from 2 to 8 carbon atoms.  
   
   
       39 . The catalyst according to anyone of the previous claims  37  and  38 , wherein said Al/(D+D p ) ratio ranges from 0.2 to 1.3, preferably from 0.3 to 1.0.  
   
   
       40 . The catalyst according to any of the previous claims from  37  to  39 , wherein said solid component is activated in two successive steps by reaction in the first step with an aluminum trialkyl (n=3 in formula (III)), and in the second step with an aluminum dialkyl chloride (n=2, X=Cl, in formula (III)), in such a quantity that the overall molar ratio Al/(D+D p ) ranges from 0.1 to 1.3, preferably from 0.4 to 1.1.  
   
   
       41 . The catalyst according to  claim 40 , wherein, in said first step the molar ratio AlR 3 /(D+D p ) ranges from 0.1 to 0.4 and in the second step the molar ratio AlR 2 Cl/(D+D p ) ranges from 0.2 to 0.6.  
   
   
       42 . A process for the (co)polymerization of ethylene, comprising reacting ethylene and optionally at least one alpha-olefin, under suitable polymerization conditions, in the presence of said catalyst according to any of the previous claims from  32  to  41 .  
   
   
       43 . The process according to  claim 42 , carried out in gas phase with the fluid-bed method, wherein a gaseous stream of ethylene and optional alpha-olefin is reacted in the presence of a sufficient quantity of catalyst, at a temperature ranging from 70 to 115° C., and at a pressure ranging from 500 to 1000 kPa.  
   
   
       44 . The process according to the previous  claim 43 , wherein said stream is introduced from the bottom of the polymerization reactor, partially comprising a stream in liquid form.  
   
   
       45 . The process according to anyone of  claim 43  and  44 , in the presence of a catalyst according to any of the previous claims from  37  to  41 .  
   
   
       46 . The process according to any of the preceeding claims from  42  to  45 , wherein the molar ratio with ethylene ranges from 0.1 to 1.0.  
   
   
       47 . The process according to any of the preceeding claims from  42  to  46 , wherein said α-olefin is selected from 1-butene, 1-hexene and 1-octene and is in such a quantity that the molar ratio with ethylene ranges from 0.1 to 0.4.  
   
   
       48 . The process according to any of the preceeding claims from  42  to  47 , for obtaining linear polyethylene having a density ranging from 0.915 to 0.950 g/ml,  
   
   
       49 . The process according to any of the preceeding claims from  43  to  47  for obtaining linear polyethylene having a density lower than 0.915 g/ml, preferably ranging from 0.900 to less than 0.915 g/ml, comprising the copolymerization in gas phase of a gaseous mixture including ethylene and at least one alpha-olefin having from 4 to 10 carbon atoms.  
   
   
       50 . The process according to  claim 49 , wherein the gaseous mixture of ethylene and the at least one alpha-olefin is reacted in the presence of a sufficient quantity of catalyst, at a temperature ranging from 70 to 95° C., and a pressure ranging from 500 to 1000 kPa.  
   
   
       51 . The process according to any of the previous claims  49  and  50 , wherein said alpha-olefin is selected from 1-butene, 1-hexene and 1-octene, and is in such a quantity that the molar ratio with respect to ethylene ranges from 0.1 to 0.4.  
   
   
       52 . The process according to any of the previous claims from  42  to  51 , wherein said catalyst is formed in situ inside the reactor.  
   
   
       53 . The process according to any of the previous claims from  42  to  52 , wherein said linear polyethylene has a weight average molecular weight M w  ranging from 20,000 to 500,000 and a MWD (M w /M n ) distribution ranging from 2.5 to 4.