Abstract: The present invention discloses a method for preparing an activating support and its use to activate metallocene or post-metallocene catalyst component for use in the oligomerization and polymerization of ethylene and alpha-olefins.

Abstract: The present invention is a process for making an olefin product from an oxygen-containing organic feedstock comprising: providing a mixture of said oxygen-containing feedstock, an hydrocarbon and optionally an inert diluent, contacting said mixture in a reaction zone having an inner surface (the MTO reactor) with a zeolitic catalyst at conditions effective to convert at least a part of the oxygen-containing organic feedstock to olefin products (the MTO reactor effluent), recovering a reactor effluent comprising light olefins, a heavy hydrocarbon fraction and undesired by-products, wherein: at least a part of the inner surface is passivated such that the undesired by-products are reduced by comparison with a non passivated inner surface and for one or more sulphur compound is co-injected with the said oxygen-containing feedstock and the hydrocarbon and said sulphur compound is capable to reduce the undesired by-products by comparison with a non injection of sulphur compound.