Supported, titanized chromium catalyst and its use for preparing homopolymers and copolymers of ethylene
Novel supported, titanized chromium catalysts for the homopolymerization of ethylene and the copolymerization of ethylene with α-olefins, a process for preparing them and to their use for the polymerization of olefins.
1. A supported, titanized chromium catalyst obtained by a process which comprises the following steps:
A) bringing a spherical, spray-dried, oxidic support material into contact with a titanium compound in a suspension,
B) bringing the support material which has been treated in this way into contact with a chromium salt solution in a suspension and subsequently removing the solvent,
C) optionally, calcining the precatalyst obtained in step B) at above 280° C. in an inert gas atmosphere and subsequently
D) activating the precatalyst obtained in step B) or C) at from 500° C. to 800° C. in an oxygen-containing atmosphere.
2. The supported, titanized chromium catalyst of claim 1 having a chromium content of from 0.1 to 5% by weight and a titanium content of from 0.5 to 10% by weight.
3. The catalyst of claim 1 , wherein the oxidic support material is a silica gel.
4. The catalyst of claim 1 , wherein the pore volume of the support material is from 0.5 to 3 ml/g.
5. The catalyst of claim 1 , wherein the specific surface area of the support material is from 50 to 600 m 2 /g.
6. The catalyst of claim 1 , wherein the mean particle size of the support material is from 1 to 1000 μm.
7. The catalyst of claim 1 , wherein the support material is slurried with an acid before being brought into contact with the titanium compound.