Preactivated catalytic complex spogospheres

Abstract

Abstract Storage stability of Ziegler-type catalysts for α-olefin polymerization and having a specific surface greater than 75 m 2 /g is improved by treating the catalysts with a preactivator which is an organic compound of a metal of one of Groups Ia, IIa, IIb and IIIa of the Periodic Table. CROSS-REFERENCE TO RELATED APPLICATION The invention described herein is directly related to that described in copending Application Ser. No. 236,407, filed Mar. 21st, 1972. The entire text of that application is incorporated herein by reference. BACKGROUND OF THE INVENTION Ziegler-type microporous catalytic complexes having a specific surface area greater than 75 m 2 /g and useful for the polymerization of α-olefins are prepared by (a) reducing TiCl 4 by means of an aluminum alkyl; (a') optionally isolating the reduced solid, based on TiCl 3 , from the medium in which it is formed; (b) treating this reduced solid with a complex forming agent; (c) removing any excess of the latter, if necessary; (d) bringing the solid treated in this way into contact with TiCl 4 ; and (e) isolating the catalyst complex thus formed. These catalyst complexes are characterized by a markedly greater activity than that of the previously known systems and by very good stereospecificity. However, during storage the activity of these catalysts tends to decline over the course of time. Hence it is necessary to use the catalyst shortly after its manufacture to assure reproducibility of catalyst activity. SUMMARY OF THE INVENTION The present invention is directed to imparting aging resistance to Ziegler-type microporous catalysts based on TiCl 3 and having a specific surface area greater than 75 m 2 /g and to the resulting storage stable catalysts. Such catalysts are complexes useful for stereospecific polymerization of α-olefins. Storage stability of such microporous catalysts is greatly improved by preactivation with a preactivator shortly after catalyst complex preparation. Such complexes are preactivated by bringing them into contact with a preactivator which is an organic compound of a metal of one of groups Ia, IIa, IIb and IIIa of the Periodic Table. The preparation of the catalyst complexes comprises the following steps: (a) reduction of TiCl 4 to a solid product based on TiCl 3 by means of a reducing agent of the general formula ALR n X 3-n , in which R is a hydrocarbon radical containing 1 to 18 carbon atoms, X is a halogen, and n is a number such that 0<n ≦3; (b) treatment of the thus prepared reduced solid with a complex forming agent which is an organic compound with at least one atom or group having at least one pair of free electrons capable of effecting coordination with titanium or aluminum and is a compound of one of the formulae: R'--O--R",R'--S--R",R'--SH wherein R' is a hydrocarbon radical with from 1 to 15 carbon atoms, and R" is a hydrocarbon radical with from 1 to 15 carbon atoms; (c) reaction of the resulting treated solid with TiCl 4 ; (d) isolation of the thus formed solid catalyst and, optionally, washing to remove the last traces of TiCl 4 ; and (e) preactivation of the resulting solid catalyst with a preactivator which is an organic compound of a metal of groups Ia, IIa, IIb or IIIa of the Periodic Table. Steps (a) to (d) are the same as those of the process of preparation described in the above-noted Application Ser. No. 236,407.

Inventors

• 👤 Jean-Pierre Hermans
• 👤 Paul Henrioulle

Bibliographic Details