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AssigneeSolvay Polyolefins Europe-Belgium (Societe Anonyme)
InventorsBenoit Koch, Andre Rulmont, Fabienne Wijzen
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Support for catalysts, containing at least two constituents chosen from silica, alumina and aluminium phosphate, having a specific surface of 100 to 800 m.sup.2 /g, a crystallization temperature greater than or equal to 700.degree. C. and a pore volume of 1.5 to 4 cm.sup.3 /g, the specific surface (SS) and the pore volume (PV) corresponding to the relationship: SS<(PV.times.564-358). Process for the manufacture of such a support, according to which an alcohol, water, a silicon alkoxide and an acid are mixed under conditions such that gelling or precipitation of silica is prevented, an acidic solution of an aluminium compound and/or a solution of a source of phosphate ions are added thereto, a gelling agent is added thereto, a gel is recovered which is washed with water and then by means of an organic liquid, the gel is then dried until a powder is obtained, and the powder is calcined. Polymerization of olefins in the presence of a catalyst containing chromium on a support as described above.
A support for catalysts of homogeneous and amorphous structure, containing silica, aluminium phosphate, and optionally alumina, said support having a specific surface of 100 to 800 m.sup.2 /g, a crystallization temperature greater than or equal to 700.degree. C. and a pore volume of 1.5 to 4 cm.sup.3 /g, the specific surface (SS) and the pore volume (PV) corresponding to the following relationship:
A process for the manufacture of a precursor gel of a support for a catalyst, including steps for, in a first stage, mixing an alcohol, water, a silicon alkoxide and an acid in amounts such that the water/silicon molar ratio is from 2 to 50, adding an acidic solution of an aluminium compound and/or a solution of a source of phosphate ions, in a second stage, and, in a third stage, adding a gelling agent to the hydrolysis medium thus obtained, the first stage being carried out at acid pH and the temperature during the addition of water, acid, silicon, alkoxide and alcohol being less than or equal to 30.degree. C. and, the first stage also including a maturing of the hydrolysis medium thus obtained at a temperature at least equal to 20.degree. C. and lower than the boiling temperature of the medium, so as to substitute at least part of the alkoxy groups of the silicon alkoxide by hydroxyl groups, without producing precipitation or gelling of silica.
Dependencies are inferred from the claim text.