Reactor continuity

A method of making a catalyst system having an activity greater than 1500 g of polymer per gram of supported catalyst per hour normalized to 1379 kPag (200 psig) of ethylene partial pressure and a temperature of 90° C. and a kinetic profile for a plot of ethylene consumption in standard liters of ethylene per minute against time in minutes, at a reaction pressure of 1379 kPag (200 psig) and 90° C., corrected for the volume of ethylene in the reactor prior to the commencement of the reaction, in a 2 liter reactor over a period of time from 0 to 60 minutes is such that the ratio of the maximum peak height over the first 10 minutes to the average ethylene consumption from 10 to 60 minutes taken at not less than 40 data points, is less than 3.5, comprising:

• i) impregnating a porous particulate inorganic oxide support having an average particle size from 10 to 150 microns, a surface area greater than 100 m2/g, and a pore volume greater than 0.3 ml/g with
• (ii) at least a 1 weight % aqueous solution of a metal salt selected from the group consisting of Zr(SO4)2.4H2O, ZrO(NO3)2 and Fe(NO3)3 to provide not less than 1 weight % based on the weight of the support of said salt;
• (iii) recovering the impregnated support;
• (iv) calcining said impregnated support in one or more steps at a temperature from 300° C. to 630° C. for a time from 2 to 20 hours in an inert atmosphere;
• (v) and either
• (a) contacting said calcined support with a hydrocarbyl solution containing at least 5 weight % of an aluminum activator compound of the formula:
• R122AlO(R12AlO)qAlR122
• wherein each R12 is independently selected from the group consisting of C1-20 hydrocarbyl radicals and q is from 3 to 50 to provide from 0.1 to 30 weight % of said aluminum compound based on the weight of said calcined support;
• optionally, separating said activated support from said hydrocarbyl solution and contacting said activated support with a hydrocarbyl solution containing at least 5 weight % of a single site catalyst as set out below;
• or
• (b) contacting said support with a hydrocarbyl solution containing at least 5 weight % of an aluminum activator compound of the formula:
• R122AlO(R12AlO)qAlR122
• wherein each R12 is independently selected from the group consisting of C1-20 hydrocarbyl radicals and q is from 3 to 50 and at least 5 weight % of a single site catalyst of the formula:
• wherein M is selected from the group consisting of Ti, Zr and Hf;
• Pl is a phosphinimine ligand of the formula:
• wherein each R21 is independently selected from the group consisting of a hydrogen atom;
• a halogen atom;
• C1-10 hydrocarbyl radicals which are unsubstituted by or further substituted by a halogen atom;
• C1-8 alkoxy radicals;
• C6-10 aryl or aryloxy radicals;
• amido radicals;
• silyl radicals of the formula:
• —Si—(R22)3
• wherein each R22 is independently selected from the group consisting of hydrogen, a C1-8 alkyl or alkoxy radical and C6-10 aryl or aryloxy radicals;
• and a germanyl radical of the formula:
• —Ge—(R22)3
• wherein R22 is as defined above;
• L is a monoanionic ligand selected from the group consisting of a cyclopentadienyl-type ligand;
• Y is independently selected from the group consisting of activatable ligands;
• m is 1 or 2;
• n is 0 or 1;
• p is an integer and the sum of m+n+p equals the valence state of M to provide a molar ratio of Al:Ti on the catalyst from 10:1 to 500:1;
• and
• (vi) recovering and drying the catalyst.