Single site catalysts which contain a transition metal, a cyclopentadienyl may be activated with alumoxanes in the gas, solution or group-containing ligand, and a phosphinimine ligand slurry phase polymerization of olefin. Alumoxanes contain residual aluminum alkyls which may poison the catalysts. The residual aluminum alkyls may be bound and/or removed from the alumoxanes by treatment with carbohydrates such as cellulose, starch or sugar.
