Polymerization catalysts and methods of preparation thereof
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of application Ser. No. 549,021, filed Feb. 11, 1975, now abandoned, which is a continuation of application Ser. No. 235,775, filed Mar. 17, 1972, abandoned, which is a continuation of application Ser. No. 808,638, filed Mar. 19, 1969, abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to polymerization catalysts and to a process of preparing the same. More particularly, this invention is directed to new solid catalysts which are suitable for the polymerization and the copolymerization of olefins and to a process of preparing the same. 
     U.S. Pat. No. 3,400,110 which was granted to Dassesse et al on Sept. 3, 1968 and which is incorporated herein by reference describes a process for the polymerization and the copolymerization of olefins in the presence of a catalyst obtained by activating with an organometallic compound, the reaction product of a compound of a transition metal with a solid compound comprising a hydroxychloride of a bivalent metal, which is preferably magnesium hydroxychloride, having the formula Mg(OH)Cl. 
     Though this is not yet established, it is believed that the reaction between the transition metal compound and the hydroxychloride of a bivalent metal, which produces the catalyst described in the above U.S. patent, is the result of a chemical bonding through the --OH groups of the hydroxychloride. 
     The catalytic complex comprises the following elements: 
     a bivalent metal M, preferably magnesium, 
     chlorine, 
     a transition metal M&#39; bonded to the bivalent metal through oxygen, 
     reactive groups X bonded to the transition metal. 
     The catalytic polymerization processes described in the above U.S. patent, however, require that the bivalent metals be in the form of a hydroxychloride. These compounds which are not commercially available, cannot be obtained without difficulty and are costly to prepare. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide transition metal catalysts chemically bonded to supports and a method of preparation thereof from readily available and/or easily prepared solid supports. 
     Another object of the present invention is the provision of catalysts having advantageous and improved properties and a method of preparation therefore, wherein the catalysts are obtained by the reaction of a transition metal compound reacted with a inorganic support. 
     Still another object of this invention is the provision of an improved method of polymerization and copolymerization of olefins and particularly of α-olefins with one another and with diolefins. 
     A further object of the present invention is the provision of an improvement in the method of polymerizing olefins as described in the above mentioned patent to Dassesse et al. 
     It has now been found that supported catalysts having certain specific advantages over the catalysts derived from hydroxychlorides are easily prepared. 
     According to the present invention, catalysts for the polymerization and the copolymerization of olefins are comprised of an organometallic compound and the reaction product between a transition metal derivative and a solid support whose composition, at least at the surface thereof, corresponds to the formula M(OH) x  X y .nH 2  O wherein X is a halogen, M is a bivalent metal, 1&gt;x&gt;0, y equals 2-x and 1&gt;n≧0. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The solid supports which are used to carry out the object of the present invention may easily be obtained by partial hydrolysis of a bivalent metal halide, which may be carried out either before contact with the transition metal derivative or simultaneously therewith. 
     When the partial hydrolysis of the bivalent metal halide is carried out before contact with the transition metal derivative, the operation may be effected by contacting the anhydrous halide with water vapor heated to a suitable temperature, generally higher than 100° C. 
     The operation may also be carried out by simply heating a hydrated bivalent metal halide at a temperature between 50° and 350° C. since, upon drying of the hydrated product, there is a partial hydrolysis if the operating conditions are well chosen. 
     According to one of the most preferred embodiments of the invention, the partial hydrolysis of the halide may be carried out at the same time as the bonding of the derivative of a transition metal. In this case, the operation is preferably carried out by utilizing a slightly hydrated halide, i.e. a halide containing about 0.5 to 5 mols of water per molecule and particularly a monohydrate. The partial hydrolysis is produced by the water of hydration which has evolved during the heating step. 
     The possibility of partially hydrolyzing the halide simultaneously, as the bonding of the transition metal derivative on the support is carried out, is particularly unexpected since it has been generally believed that the presence of free water during the bonding reaction is detrimental to the reaction and also that free water results in the production of catalysts having unsuitable properties. 
     For this reason the supports have always been dried with utmost care prior to the reaction. 
     It has now been discovered that the presence of small amounts of water of hydration, can be tolerated during the bonding reaction, if measures are taken to prevent the reaction from being too violent and to assure that the reaction mixture does not solidify. 
     The solid supports which bind the transition element derivatives should have, at least at the surface thereof, a composition corresponding to the formula M(OH) x  X y .nH 2  O in which M is a bivalent metal selected from the group comprising magnesium, calcium, chromium, manganese, iron, nickel, cobalt, copper, zinc and cadmium X is a halogen, selected from the group comprising chloride, fluorine, bromine or iodine, x is higher than 0 and lower than 1, preferably between 0.1 and 0.8, y equals 2-x and n is lower than 1, preferably in the neighborhood of, or equal to 0. 
     These reactive supports can be obtained by one of the above defined methods of hydrolysis, from the corresponding halides or hydrated halides. 
     In practice, the easiest method of hydrolysis is generally chosen and this depends on the nature of the product which is available and on its properties. 
     The granulometry of the support is not critical and has very little influence on the bonding reaction. However, the aspect and the granulometry of the polymer is dependent on the granulometry of the support. For this reason, it is preferred to use supports having a coarse granulometry in which the particles have an average diameter higher than 10 microns. 
     The transition metal derivatives which may be used for the preparation of the polymerization catalysts are selected from the group consisting of the derivatives of the metals of Groups IVb, Vb and VIb of the Periodic Table, such as the halides, oxyhalides, alkoxyhalides, oxyalkoxides, and alkoxides of these metals. The derivatives which are liquid under the reaction conditions are preferred, such as TiCl 4 , TiCl 2  (OC 2  H 5 ) 2 , Ti(OC 4  H 9 ) 4 , VCl 4 , VOCl 3 , VO(OC 4  H 9 ) 3  and CrO 2  Cl 2 . 
     The reaction between the transition metal derivative and the reactive support is preferably carried out in the absence of solvent by simply suspending the support or its precursor in the transition metal derivatives used practically pure in liquid form, to prevent a precipitation of hydrolysis products which have only little activity and are undesirable during the polymerization process. 
     However, the reaction between extensively hydrated derivatives, particularly monohydrated halides, and certain transition metal derivatives, particularly halides and oxyhalides, may be highly exothermic and, if there is an appreciable heating of the reaction mixture, this may lead to a complete solidification thereof, or at least, it may produce catalysts which are only slightly active. For this reason, when the reaction is likely to be highly exothermic, as with the uses of the most highly hydrated halides employed in the present process, the process is carried out under conditions which prevent overheating. 
     Generalized overheating may be avoided by the use of a relatively large quantity of liquid; however, local overheating at the surface of the solid causes lumping and solidification thereof which should be prevented. It is preferable, therefore, to mix the hydrate with the halide initially at a temperature of about 10° to 40° C., most preferably at ambient temperature with violent stirring. In addition, the liquid phase, pure halide, or solvent and halide, should be present in large excess in the reaction medium; the weight ratio of liquid to solid should be preferably comprised between 50:1 and 3:1 more advantageously from 20:1 to 4:1. 
     Other expedients may also be taken to avoid localized overheating. For example, a stream of the cooled transition metal derivative may be circulated on the support, at such a speed that even localized overheating is avoided. It is also possible to allow the support, in powder form, to fall as a mist, in a large quantity of cold transition metal derivative. 
     The suspension is then heated to a suitable temperature in order that the reaction be carried out at a temperature generally comprised between 40° and 180° C. 
     After the bonding reaction, the resulting solid catalyst may be extracted by means of the transition metal derivative itself heated to a temperature between 40° and 180° C. 
     A certain amount of transition metal derivative remains bonded on the solid substance to constitute the catalyst support and it cannot be removed therefrom by physical means alone. It has indeed been observed that a certain amount of transition metal compound is not eliminated when washing with a hydrocarbon solvent even after the bonding reaction. 
     The resulting catalytic complex comprises the essential elements of catalytic complexes which have previously been derived from bivalent metal hydroxychloride, for example: 
     a bivalent metal M, preferably magnesium, calcium, manganese or cobalt, 
     a halogen, 
     oxygen, 
     a transition metal chemically bonded to the support through oxygen, 
     various substituents, which may be halogenated, bonded on the transition metal. 
     In the new catalysts, however, the composition and the nature of the substance of the support can differ from the surface thereof, since partial hydrolysis may be limited to superficial layers of the support for the production of active complexes. Furthermore, the proportions of these various elements are different than those of previously obtained catalytic complexes. Particularly, the halogen/M ratio differs from 1. 
     After the washing step, the resulting catalyst must be activated by contacting it with an organometallic derivative of a metal of Groups I, II, IIIa or IVa of the Periodic Table. As used herein, the term organometallic compounds includes organosilicon compounds in accordance with the usage in Organometallic Chemistry--Selected Topics in Modern Chemistry by E. G. Rochow, Reinhold Publishing Corp., 1964 and The Chemistry of Organometallic Compounds, by E. G. Rochow. D. T. Hurd and R. N. Lewis, John Wiley and Sons, 1957. Organometallic halides and hydrides and completely alkylated derivatives thereof, such as dialkylaluminum halides, alkylmagnesium halides, alkylaluminum hydrides, alkyltin hydrides, and organic compounds of silicon having at least one Si--H bond may be used as activators, wherein trialkyl aluminum compounds are preferred, As examples of such activators triethylaluminum, triisobutylaluminum, tri-n-octylaluminum, diethylaluminum chloride, ethylmagnesium bromide, diisobutylaluminum hydride, tri-n-butyltin hydride, triethylsilane, methyl hydrogen silicone oil may be mentioned. 
     The amount of activator employed is not critical as long as there is a molar excess thereof over the transition metal bonded on the support. The activator/bonded transition metal molar ratio is preferably between 10 and 50. 
     The activation may be carried out immediately before introducing the monomers; however, the catalyst may also be allowed to age at room temperature or higher, for a more or less extended period of time. 
     The catalysts according to the invention are used for the polymerization and the copolymerization of olefins, such as for the production of polyethylene, polypropylene and ethylene-propylene copolymers. The present catalyst may also be used for the copolymerization of α-olefins with diolefins including linear aliphatic, monocyclic and alicyclic dienes having an endocyclic bridge such as 1,4-pentadiene, 1,3-divinylcyclohexane and norbornadiene. 
     When used for the polymerization of ethylene, it has been found that the catalysts according to the present invention have extremely high activities and the polyethylene produced therewith has exceptional properties. The linearity of polyethylene so produced is such that it contains less than one CH 3  group per 1,000 carbon atoms. The product contains no trace of transinternal unsaturation and only 0.01 to 0.20 vinyl double bonds and 0.01 to 0.1 vinylidene double bonds per 1,000 carbon atoms. The specific weight of this product is equal to or higher than 0.968 g./cm. 3 , which makes it particularly suitable for injection molding applications. 
     Besides these properties which are common to a certain number of catalysts chemically bonded to supports, the catalysts according to the present invention possess particularly advantageous characteristics. 
     They are particularly suitable for the production of low, and even very low molecular weight polyethylene, without requiring the use of very high partial pressures of hydrogen. 
     In addition, these catalysts are much less sensitive than most of the known catalysts to the poisoning action of agents destroying the activity of polymerization catalysts, such as water and oxygen. 
     Finally, these new catalysts are characterized by a high stability, a low content of transition element compounds and an extremely high activity, with the consequence that only a very low amount can be found as inert, harmless residues in the product coming out of the polymerization reactor. For this reason no purifying treatment is required and the polymerized product may be used as such. The production of the new catalysts according to the invention, allows a very important simplification of the polymerization apparatuses and a corresponding reduction of the cost of the product. 
     Also, the ethylene-propylene copolymers obtained by the process according to the invention have a particularly high propylene content which are characterized by an amorphous structure and by excellent elastomeric properties. 
     The polymerization and the copolymerization may be carried out according to any known procedures, in the gaseous phase, in the absence of a liquid medium which is a solvent of the monomer, or in the presence of a dispersing medium in which the monomer is soluble. An inert hydrocarbon which is liquid under the conditions of polymerization or the monomers themselves, in a liquid state under their pressure of saturation, may be used as a liquid dispersing medium. 
     To produce elastomeric copolymers of ethylene and propylene, the catalysts according to the invention may be used in suspension in the liquid monomers, resulting in granular products which are easily handled. With most of the known catalysts, on the contrary, under these conditions, a compact rubbery mass is obtained, which is not easily handled; furthermore, the reaction must be carried out in solution. 
     The following examples are given to illustrate the best modes currently contemplated for carrying out the invention, but are not to be construed as restricting the scope thereof. 
    
    
     EXAMPLE 1 
     Magnesium fluoride is hydrolyzed in a glass reactor heated to 400° C., by contacting 20 g. of pure MgF 2  intended for analysis, with nitrogen, saturated with water by bubbling at a temperature of 70° to 80° C. 
     After a reaction period of 6 hours, the entry of wet nitrogen is stopped, the reaction mixture is flushed for 6 hours with dry nitrogen at 300° C., the content of the reactor is allowed to cool and crushed. The resulting product contains 8.5 g. of hydroxyl groups per kilogram measured with a thermoscale. 
     Of this product, 11.5 g. are placed in a glass reactor provided at the lower portion thereof with a sintered glass plate and having a cooler at the upper portion thereof. Cold TiCl 4  in an amount of 50 ml. is introduced and after 5 minutes contact at ambient temperature, the mixture is heated at 130° C. for 1 hour. TiCl 4  is then separated by filtration through the sintered glass plate and the content of the reactor is washed 20 times with hexane. The resulting catalytic complex contains 3.8 g. of Ti/kg. 
     The above solid catalyst in an amount of 1.019 g. is suspended in 500 ml. of hexane, in a 1.5 liter stainless steel autoclave. In this suspension, there are introduced 2 ml. of a solution containing 500 g. per liter of triisobutylaluminum in hexane. The temperature of the autoclave is raised to 80° C. and ethylene is introduced under a pressure of 4 kg./cm. 2  and hydrogen under a pressure of 8 kg./cm. 2 . 
     After a reaction period of 2 hours under a pressure which remains constant through a continuous addition of ethylene, the autoclave is degassed and 132 g. of polyethylene are extracted, which corresponds to a catalytic activity of 4300 g. of PE/h.g.Ti.atm. C 2  H 4 . 
     By way of comparison, polymerization was carried out under identical conditions, but using a catalyst obtained from MgF 2  which has not been partially hydrolyzed and to which 1.5 g. Ti/kg. had been bonded. After 2 hours, only traces of polymer were produced. 
     EXAMPLES 2 TO 4 
     MgBr 2  samples were prepared with different rates of hydrolysis by submitting identical samples of pure MgBr 2 .6H 2  O intended for analysis to thermal treatments which are increasingly prolonged and severe. 
     The treatment conditions and the analytical data concerning the resulting products are given in the following Table 1. 
     
                                           TABLE 1                                 
__________________________________________________________________________
          Example 2                                                       
                   Example 3                                              
                            Example 4                                     
__________________________________________________________________________
Conditions of                                                             
          3 hr. at 120° C.                                         
                   40 hr. at 110° C.                               
                            1 hr. at 100° C.                       
hydrolysis                                                                
          4 hr. at 160° C.                                         
                   24 hr. at 130 ° C.                              
                            4 hr. at 200° C.                       
                   6 hr. at 140° C.                                
                            1.5 hr. at 205° C.                     
Analytical data                                                           
of hydrolysis                                                             
product                                                                   
Mg g./kg. 114      133      188                                           
Br g./kg. 669      672      694                                           
OH + H.sub.2 O g./kg.                                                     
          217      185      118                                           
(determined by                                                            
difference)                                                               
Rough estimate                                                            
          MgBr.sub.1.8 (OH).sub.0.2                                       
                   MgBr.sub.1.5 (OH).sub.0.5                              
                            MgBr.sub.1.1 (OH).sub.0.9                     
of formula                                                                
          2.4 H.sub.2 O                                                   
                   1.5 H.sub.2 O                                          
__________________________________________________________________________
 
    
     About 11 g. of each of the above described hydrolysis products are allowed to fall in powder form into 50 ml. of pure TiCl 4  at room temperature and the mixture is heated to 130° C. under stirring for 1 hour; then the solid product is transferred into the basket of a Kumayawa type extractor and the extraction is carried out for 1 hour with boiling TiCl 4 . Washing is carried out with hexane until elimination of all traces of TiCl 4  which are not chemically bound. 
     The resulting solid products were used to polymerize ethylene according to the procedure described in Example 1. The specific operating conditions of each polymerization and the results obtained are given in Table 2. 
     
                       TABLE 2                                                     
______________________________________                                    
             EX-     EX-       EX-                                        
             AMPLE 2 AMPLE 3   AMPLE 4                                    
______________________________________                                    
Analytical data concern-                                                  
ing the catalytic                                                         
complexes                                                                 
Mg g./kg.      119       158       190                                    
Br g./kg.      383       347       694                                    
Cl g./kg.      246       317       5                                      
Ti g./kg.      87        48        0.7                                    
OH + H.sub.2 O (determined                                                
               165       130       110                                    
by difference) g./kg.                                                     
Ratio OH + H.sub.2 O/Mg                                                   
               1.87      1.12      0.83                                   
Polymerization                                                            
Quantity of catalytic                                                     
               0.115     0.193     2.00                                   
complex g.                                                                
Quantity of activator                                                     
               1.000     1.000     0.900                                  
[Al(iBu).sub.3 ] g.                                                       
Temperature °C.                                                    
               80        80        80                                     
Duration hr.   2         1         2                                      
Partial pressure                                                          
               4         6.33      4                                      
C.sub.2 H.sub.4 kg./cm..sup.2                                             
Partial pressure H.sub.2                                                  
               8         --        8                                      
Quantity of PE 58        215       92                                     
produced g.                                                               
Specific activity                                                         
               730       3730      8100                                   
g.PE/hr.g.Ti atm. C.sub.2 H.sub.4                                         
Total productivity                                                        
               504       1110      46                                     
g.PE/g. cat.complex                                                       
______________________________________                                    
 
    
     It is therefore realized that if a certain quantity of water which is present in the support used for the preparation of the catalytic complex is not absolutely harmful, the catalytic activity is nevertheless decreased. However, the presence of water causes an increase of the quantity of transition element bonded to the support, which in some cases, increases the productivity of the catalyst. 
     The water, which is present in the support reacting with TiCl 4 , is in excess in the case of Examples 2 and 3, but ensures in this case the continuation of the hydrolysis in the reaction medium. The latter is also accompanied by a dehydration and leads to the formation &#34;in situ&#34; of a support showing the desired composition. 
     In the catalysts of this invention, the range of bonded transition metal per support material extends practically from 0.5 to 130 g./kg., and preferably from 5 to 70 g./kg. A very small amount of transition metal fixed, even if it is extremely active, means a low productivity per g. of catalytic complex and a larger quantity of support present in the polymer after reaction. On the contrary, a high amount of fixed titanium, is nearly always associated with a low activity of the titanium. So the medium range from 5 to 70 g./kg. is preferred. 
     EXAMPLES 5 TO 8 
     A series of catalytic complexes are prepared from MgCl 2 .H 2  O using the simultaneous partial hydrolysis and bonding technique, by reacting MgCl 2 .H 2  O with TiCl 4  in the manner described in Example 1. The reactions and the analyses of the catalytic complexes obtained are given in the following Table 3. 
     
                                           TABLE 3                                 
__________________________________________________________________________
Example 8                                                                 
(comparative)          Example 5                                          
                             Example 6                                    
                                   Example 7                              
__________________________________________________________________________
12.86.sup.1                                                               
       Quantity of MgCl.sub.2.H.sub.2 O g.                                
                       16.92 11.997                                       
                                   12.0                                   
50     Quantity of TiCl.sub.4 ml.                                         
                       50    50    50                                     
130    Temperature of reaction °C.                                 
                       130   130   130                                    
1      Duration of reaction hr.                                           
                       1     1     3.75                                   
156    Ti content of product g./kg.                                       
                       12    16    22                                     
580    Cl content of product g./kg.                                       
                       661   666   704                                    
134    Mg content of product g./kg.                                       
                       222   222   229                                    
130    OH content determined by g./kg.                                    
                       105   96    45                                     
       difference                                                         
1.4    Ratio OH/Mg     0.68  0.62  0.28                                   
--     Ratio Cl added/Ti                                                  
                       4.3   4.1   4.1                                    
__________________________________________________________________________
 .sup.1 Test carried out with more highly hydrated Mg halide:             
 MgCl.sub.2.1.75 H.sub.2 O prepared by drying MgCl.sub.2.6 H.sub.2 O      
 
    
     The data given in Table 3 show that the bonding of TiCl 4  on MgCl 2 .H 2  O is accompanied by the formation of a derivative which is more or less hydroxylated according to the reaction conditions. According to these data, it would appear that TiCl 4  is added at least stoichiometrically as such to this derivative to give a catalytic complex. 
     Polymerization reactions were carried out with the solid catalysts prepared as described above, according to the mode of operation of Example 1, under the conditions specified in Table 4. 
     
                                           TABLE 4                                 
__________________________________________________________________________
                                      RESULTS                             
Catalyst                                                                  
      POLYMERIZATION CONDITIONS                    Producti-              
Prepared                                                                  
      Amount of                                                           
            Triiso-                   Poly- Catalytic                     
                                                   vity g. of             
in    solid cata-                                                         
            butyl alumi-                                                  
                       Partial Partial                                    
                                      ethylene                            
                                            activity                      
                                                   PE/g. of               
Example                                                                   
      lyst used                                                           
            num used                                                      
                  Duration                                                
                       pressure                                           
                               pressure                                   
                                      produced                            
                                            g.PE/g.Ti.h.                  
                                                   solid                  
                                                         Melt index       
Nos.  mg.   mg.   hr.  C.sub.2 H.sub.4 kg./cm..sup.2                      
                               H.sub.2 kg./cm..sup.2                      
                                      g.    atm. C.sub.2 H.sub.4          
                                                   lyst  g./10            
__________________________________________________________________________
                                                         min.             
5     988   1000  2    2       4      84    1800   85    13.7             
6     450   1000  2    2       4      13    448    29     6.3             
7     220    200  2    2       4       5    260    23    --               
.sup. 8.sup.c                                                             
      167    200  2    2       4       3     28    18    --               
__________________________________________________________________________
 .sup.c Comparative                                                       
 
    
     The results given in Table 2 show the advantages of using the catalysts according to the invention which have been prepared from catalytic complexes in which the OH/Mg ratio is lower than 1 and which has been obtained from monohydrated halide, over related catalysts, such as the one described in Example 8, given by way of comparison, in which the OH/Mg ratio of the catalytic complex is higher than 1, and which is derived from a more extensively hydrated halide. 
     These results also illustrate the exceptional sensitivity of the better catalysts towards hydrogen, i.e. those obtained from catalytic complexes in which the OH/Mg ratio is higher than 0.5 (Examples 5 and 6). For example, with partial pressure of hydrogen attaining only 4 kg./cm. 2 , these catalysts produce polyethylene in which the melt index reaches 13 g. per 10 minutes while with known catalysts such as those described in U.S. Pat. No. 3,400,110 polyethylene has a melt index of only about 8 g. per 10 minutes. 
     EXAMPLE 9 
     8.24 g of MgCl 2 .H 2  O are reacted with 20.88 g. of TiCl 2  (OC 2  H 5 ) 2  in solution in heptane during 1 hour at 100° C. in the apparatus described in Example 1. The product obtained is carefully washed with heptane, then with hexane, and is then dried under vacuum until the weight remains constant. 
     The composition of the resulting product is the following: 
     Mg: 135 g./kg. 
     Cl: 474 g./kg. 
     Ti: 110 g./kg. 
     The OH+H 2  O/Mg ratio of this product is estimated to be 0.85. 
     This solid catalyst is in an amount of 0.317 g. and 1.0 g. of triisobutylaluminum are used to carry out the polymerization of ethylene according to the procedure described in Example 1, under partial pressures of ethylene and hydrogen, respectively of 8 kg./cm. 2  and 16 kg./cm. 2 . After 2 hours, 10 g. of polyethylene are obtained, representing a catalytic activity of 19 g. PE/h.g.Ti.atm. C 2  H 4 . 
     EXAMPLE 10 
     As described above, 8.72 g. of MgCl 2 .H 2  O are reacted with 19.1 g. of CrO 2  Cl 2  dissolved in 40 ml. of pure CCl 4 . After 2 hours at 100° C., the mixture is cooled, then the solid product is washed with hexane and dried under vacuum. 
     There are obtained 8.44 g. of a solid product having the following composition: 
     Mg: 212 g./kg. 
     Cl: 604 g./kg. 
     Cr: 6.7 g./kg. 
     A polymerization test carried out with 1.01 g. of the above solid catalyst, 0.5 g. of Al(iBu) 3  and ethylene under a pressure of 20 kg./cm. 2  has given 2.5 g. of polyethylene during 5 hours. 
     EXAMPLE 11 
     26 g. of pure MgI 2 .8H 2  O intended for analysis, are dried under vacuum, first at room temperature then by progressively heating to 140° C. There are obtained 18 g. of a product having the following rough estimate formula MgI 1 .5 (OH) 0 .5.3.3H 2  O. 
     This product is reacted with TiCl 4  under the conditions given in Example 2 to give a solid catalyst having the following analysis: 
     Mg: 150 g./kg. 
     I: 284 g./kg. 
     Cl: 360 g./kg. 
     Ti: 38 g./kg. 
     H 2  O+OH (determined by difference): 168 g./kg. 
     The OH+H 2  O/Mg ratio of this catalyst has been estimated at about 1.55 and the Cl/Ti ratio, at 12.8, which indicates that most probably there has been a chlorine-iodine exchange. 
     Polymerization carried out according to the mode of operation given above, with 0.135 g. of this solid catalyst and 0.2 g.of triisobutyl aluminum used as activator, has produced 107 g. of polyethylene after 30 minutes under partial pressures of ethylene and hydrogen, respectively of 4 kg./cm. 2  and 8 kg./cm. 2 . The catalytic activity was 10,520 g. PE/h.g. Ti.atm. C 2  H 4  and the productivity was 800 g. PE by g. of solid catalyst. The melt index of the product was 16.0 g. per 10 minutes. 
     EXAMPLE 12 
     FeCl 2 .4H 2  O in an amount of 40 g. was dried for 8 hours at 100° C. with a flow of pure, dry HCl. There are obtained 29 g. of a product having the following rough estimate formula: FeCl 2 .1.2H 2  O. 
     This product is used as catalyst support and contacted with pure TiCl 4  at a temperature of 140° C. according to the mode of operation of Example 1. 
     The resulting solid catalyst has the following composition: 
     Fe: 410 g./kg. 
     Cl: 545 g./kg. 
     Ti: 11 g./kg. 
     H 2  O or OH (determined by difference): 34 g./kg. 
     The OH/Fe ratio is 0.28 and the &#34;additional Cl/Ti&#34; ratio is 4.87. 
     The polymerization of ethylene carried out under the conditions of Example 1 with 0.238 g. of solid catalyst and 0.200 g. of triisobutylaluminum used as activator, under partial pressures of ethylene and hydrogen, respectively of 2 kg./cm. 2  and 4 kg./cm. 2 , has resulted in 151 g. of polyethylene after 2 hours. The catalytic activity was 10,280 g. PE/h.g.Ti.atm. C 2  H 4  and the productivity was 634 g. PE/g. of solid catalyst. 
     EXAMPLE 13 
     50 g. of NiCl 2 .6H 2  O were suspended in 100 ml. of SOCl 2  and heated under reflux for 2 hours. The solid product was poured off and washed in hexane, then dried. The resulting product has the following rough estimate formula: NiCl 2 .1.1H 2  O. 
     The reaction with TiCl 4  is carried out as specified in Example 2 and has produced a solid catalyst comprising: 
     Ni: 376 g./kg. 
     Cl: 501 g./kg. 
     Ti: 23 g./kg. 
     OH (determined by difference): 100 g./kg. 
     which means that the OH/Ni ratio is 0.92 and the &#34;additional Cl/Ti&#34; ratio is 2.3. 
     The polymerization carried out with 0.589 g. of this solid catalyst and 0.200 g. of Al(iBu) 3  under the conditions specified in Example 17 has produced 75 g. of polyethylene, indicating a catalytic activity of 1400 g./h.g.Ti.atm. C 2  H 4 . 
     EXAMPLE 14 
     Example 13 is repeated by replacing NiCl 2 .6H 2  O with CoCl 2 .6H 2  O. Drying with SOCl 2  has given a product of the formula CoCl 2  0.42H 2  O which by contact with TiCl 4  under the usual conditions has produced a solid catalyst having the following compositions: 
     Co: 415 g./kg. 
     Cl: 503 g./kg. 
     Ti: 26 g./kg. 
     OH (determined by difference): 56 g./kg. 
     representing an OH/Co ratio of 0.23. 
     The polymerization of ethylene carried out with 0.300 g. of this solid catalyst and 1.0 g. of Al(iBu) 3  as activators, under the conditions specified in Example 12 has produced 130 g. of PE representing a catalytic activity of 4200 PE/h.g.Ti.atm. C 2  H 4 . 
     EXAMPLES 15 TO 17 
     The reaction described in Example 13 is repeated once again using MnCl 2 .4H 2  O. After drying with SOCl 2 , the solid product has the formula MnCl 2 .H 2  O. The monohydrate is reacted with TiCl 4  and after washing the reaction product has the following composition: 
     Mn: 401 g./kg. 
     Cl: 540 g./kg. 
     Ti: 9.1 g./kg. 
     OH (determined by difference): 50 g./kg. 
     or a OH/Mn ratio of 0.31 and an &#34;additional Cl/Ti&#34; ratio of 2.84. 
     This solid catalyst was used to carry out the polymerization according to the usual procedure, but using various activators. The results of these polymerizations are given in the following Table 5. 
     
                       TABLE 5                                                     
______________________________________                                    
            EX-     EX-        EX-                                        
            AMPLE 15                                                      
                    AMPLE 16   AMPLE 17                                   
______________________________________                                    
Quantity of solid                                                         
              0.410     0.606      0.589                                  
catalyst g.                                                               
Activator:                                                                
nature        Al(iBu).sub.3                                               
                        AlEt.sub.2 Cl                                     
                                   ZnEt.sub.2                             
quantity g.   1.00      1.00       0.99                                   
Duration of poly-                                                         
              2         2           2                                     
merization h.                                                             
Partial pressure                                                          
              2         2          15                                     
C.sub.2 H.sub.4 kg./cm..sup.2                                             
Partial pressure                                                          
              4         4          --                                     
H.sub.2 kg./cm..sup.2                                                     
Polyethylene  151       79         163                                    
produced g.                                                               
Catalytic activity                                                        
              10,280    3,620      1,025                                  
g.PE/h.g.Ti.atm.C.sub.2 H.sub.4                                           
Melt index of 12.3*     2.1**      --                                     
PE g./10 min.                                                             
______________________________________                                    
 *charge = 2.16 kg.                                                       
 **charge = 21.6 kg.                                                      
 
    
     EXAMPLE 18 
     The MnCl 2  monohydrate prepared in Examples 15 to 17 is used again, this time to be reacted with VOCl 3 . The reaction is carried out at 100° C. in heptane. After washing in hexane and drying, there is obtained a solid catalyst having the following composition: 
     Mn: 380 g./kg. 
     Cl: 480 g./kg. 
     V: 6.5 g./kg. 
     Polymerization is carried out with 1.233 g. of this solid catalyst and 1.0 g. of Al(iBu) 3  under a partial pressure of ethylene of 20 kg./cm. 2  has produced 5 g. of polyethylene. 
     EXAMPLE 19 
     The solid catalyst prepared in Examples 15 to 17 which contains 9.1 g. Ti/kg. was used for the copolymerization of ethylene and propylene. 
     This copolymerization is carried out by successively introducing into a 1.5 liter autoclave, dried and flushed with a flow of propylene, 5 ml. of a solution containing 200 g. per liter of Al(iBu) 3  in hexane, 0.143 g. of solid catalyst and 335 g. of liquid propylene. The reaction mixture is heated to 40° C. and hydrogen and ethylene are introduced under respective partial pressures of 0.2 kg./cm. 2  and 19.3 kg./cm. 2 . 
     After 30 minutes, the content of the autoclave is degassed and 237 g. of a copolymer of ethylene and propylene containing 69 moles % of propylene are collected. The catalytic activity is 364,000 g. of copolymer per hour per g. of Ti. 
     EXAMPLE 20 
     The polymerization of propylene was carried out by using the same solid catalyst as in Example 19. 
     Into a 1.5 liter autoclave, previously dried and flushed with propylene, there were successively introduced 2 ml. of a solution containing 200 g. per liter of triisobutylaluminum in hexane and 0.520 g. of solid catalyst. Then, hydrogen was added under a partial pressure of 0.7 kg./cm. 2  followed by 1 liter of propylene. 
     The temperature of the reaction mixture was raised to 60° C. and maintained therein for 5 hours. After degassing the content of the autoclave, 50 g. of propylene were collected, indicating a catalytic activity of 2040 g. of PP/h.g.Ti.