Process for preparation of a catalyst with a polyolefin coat

A process for preparation of a Ziegler-Natta catalyst with a polyolefin coat, said process comprising the following steps:

• i. mixing in a reactor, a pro-catalyst and a co-catalyst in a fluid medium to obtain a slurry;
• ii. stirring said slurry in an inert gas atmosphere at a temperature in the range of 20° C. to 50° C. to homogenize the slurry and generate particles of the catalyst;
• iii. introducing a gaseous olefin monomer into the reactor having said catalyst, at a monomer pressure in the range of 1.0 kg/cm2 to 5.0 kg/cm2;
• iv. polymerizing said olefin monomer on said catalyst in a controlled manner to ensure that the degree of polymerization in the form of olefin coating is in the range of 3% to 30% of the total amount of said olefin monomer, by carrying out said polymerization at a temperature in the range of 20° C. to 50° C. under continuous stirring having a stirring speed in the range of 400 rpm to 600 rpm for a time period in the range of 120 to 180 minutes, to obtain a product mixture comprising the catalyst with the polyolefin coat and an unreacted gaseous olefin monomer;
• and
• v. venting off said unreacted gaseous olefin monomer from the reactor and separating the catalyst with the polyolefin coat from the product mixture, followed by drying to obtain the catalyst with the polyolefin coat;
• wherein said pro-catalyst is a transition metal catalyst supported on magnesium;
• wherein the transition metal is at least one metal selected from the group consisting of scandium, titanium, vanadium, chromium, iron, cobalt, nickel, copper, zirconium, chromium and palladium;
• the molar ratio of aluminum in said co-catalyst to said transition metal in said pro-catalyst is in the range of 0.5:1 to 1.5:1;
• the stirring in steps (ii) and (iv) is carried out with the help of gas dispersion hallow shaft;
• and
• the step of polymerization of said olefin monomer is carried out in the presence of nitrogen.