Hydrogen response through catalyst modification

A process for preparing an alpha-olefin polymerization catalyst composition having a productivity of greater than 2000 g of a polymer per gram of catalyst under standard gas phase operations used to manufacture a 1 MI ethylene hexene copolymer resin having a density of 0.918 g/cc, comprising contacting at a temperature from 0° C. to 100° C. a support selected from the group consisting of silica and alumina and mixtures thereof having an average particle size from about 10 to 150 microns, a surface area greater than 100 m2/g and a pore volume from about 0.3 to 5.0 ml/g, which has been heat treated to remove adsorbed water and having a residual surface hydroxyl content from 0.1 to 5 mmol/g of support, which support has been subsequently treated with an aluminum compound (Al1) of the formula R1bAl(OR1)aX3-(a+b) wherein a is either 0 or 1, b is either 2 or 3 and the sum of a+b is 3 and R1 is independently selected from the group consisting of C1-10 alkyl radicals and X is chlorine atom, reactive with the residual surface hydroxyl groups to provide from 0.5 to 2.5 wt % Al on the support, in an inert hydrocarbyl solvent or diluent with or without isolation of the treated support from the hydrocarbyl solvent or diluents;

• a transition metal compound of the formula the formula Ti(OR2)cXd wherein R2 is selected from the group consisting of a C1-4 alkyl radical and a C6-10 aromatic radical, X is selected from the group consisting of chlorine atom and bromine atom, c is 0 or an integer up to 4 and d is 0 or an integer up to 4 and the sum of c+d is the valence of the Ti atom;
• a magnesium halide prepared by reacting in situ an alkyl magnesium compound of the formula (R5)eMgX2-e wherein each R5 is independently a C1-8 alkyl radical and e is 1 or 2 and X is chlorine or bromine atom with a reactive organic halide selected from the group consisting of CCl4 and C1-6 alkyl halides and mixtures thereof;
• a second aluminum alkyl compound (Al2) of the formula R1bAl(OR1)aX3-(a+b) wherein a is either 0 or 1, b is either 2 or 3 and the sum of a+b is up to 3, and R1 is independently selected from the group consisting of C1-10 alkyl radicals and X is chlorine atom;
• and a ketone selected from the group consisting of hexanone, cyclohexanone, butanone, acetaphenone, pentanone, methyl ethyl ketone, 3-methyl-2-butanone and methyl isobutyl ketone and mixtures thereof to provide a molar ratio of electron donor to Mg from 0.5:1 to 5:1;
• a molar ratio of total Al(Al1+Al2) to Ti from 2:1 to 10:1;
• a molar ratio of Al from the second aluminum component (Al2):Ti from 1:1 to 8:1;
• a molar ratio of Mg:Ti from 2.5:1 to 10:1;
• a molar ratio of active halide from the alkyl halide to Mg from 1:1 to 6:1;
• and the titanium is present in the catalyst in an amount from 0.20 to 3.0 weight % inclusive of the support and separating the resulting catalyst from the inert hydrocarbyl solvent or diluent.