In-situ MAO derived silica supported single-site metallocene catalysts

A method for forming a supported MAO composition, comprising:

• forming a water loaded silica support with a water loading of 3-7 (mmol water/g support) for a silica support having a surface area in the range of 100-300 m2/g or 5-13 mmol water/g support for a silica support having a surface area in the range of 300-800 m2/g, provided that the at least 60% of the pores in the silica support have diameters at least 60 angstroms or larger and the total pore volume is in the range of 0.9-3 mL/g;
• treating the water loaded silica support in a closed container in a solid or slurry form for at least 10 minutes at 40 to 100° C. or in either a closed or an open container for at least 30 minutes at 0 to 40° C.;
• contacting the water loaded silica support as a solid or as a slurry with a single or multiple aluminumalkyl solution comprising at least 50 mol % TMA based on total Al that is cooled to a temperature in the range of −5 to −60° C., provided that for the water loading of 3-7 mmol/g the temperature is −5° C. or colder and for the water loading higher than 7 mmol/g the temperature is −10° C. or colder and also provided that at least a portion of the supported MAO is formed in an environment of a TMA:
• water molar ratio at 1:0.75 or higher;
• and
• heating the supported MAO at 40-130° C. for at least 1 hour or aging at ambient temperature for at least 24 hours to obtain a formed supported MAO.