Polymerization catalyst for olefines

A polymerization catalyst for olefins, comprising:

• at least one catalytically active chromium compound adsorbed on an inorganic support, wherein said catalyst is prepared by a process comprising:
• optionally subjecting the support material to a pretreatment in order to modify the number of binding sites available on the support;
• vapourizing a chromium compound used as the precursor of chromium oxide;
• routing the obtained vapour into a reaction chamber and reacting said vapour with the support material at a temperature within the range of the minimum temperature necessary to provide the activation energy for establishing chemisorption of the chromium compound onto the surface of the support up to the temperature at which the rate of desorption exceeds the rate of chemisorption of the chromium compound;
• maintaining the vapour pressure of the chromium compound sufficiently high and the duration of interaction sufficiently long so as to provide at least an equal amount of the chromium compound as there are available binding sites on the support material;
• removing the chromium compound not bound with the support material from said reaction chamber;
• and
• optionally, posttreating the heterogeneous chromium containing catalyst in order to increase its catalytic activity.