HETEROGENEOUS ZIEGLER-NATTA CATALYST COMPOSITION, A PROCESS FOR ITS PREPARATION AND A PROCESS FOR POLYMERIZING OLEFIN USING THE SAME

The present disclosure provides a Ziegler-Natta catalyst composition for preparing polymers of ethylene monomers having ultrahigh molecular weight, said composition comprises (i) a pro-catalyst component containing a reaction product of a magnesium containing compound and a titanium containing compound, characterized in that said pro-catalyst component comprises magnesium, titanium and chlorine in an amount ranging between 15 and 18 mole %; 20 and 23 mole %; and 60 and 64 mole %, respectively, all proportions being with respect to the total weight of the Ziegler-Natta catalyst composition; (ii) a co-catalyst component; and (iii) at least one external electron donor compound selected from the group of organosilane compounds having the general formula (I), wherein R1, R2, R3 and R4 are all the same or all are different, or some are the same, and are individually selected from the group consisting of linear or branched alkyl groups, cycloalkyl groups, aryl groups, alkoxy and aryloxy groups.