Patent ID: 7504463

Claim:
A process for producing an ethylene polymer in a reactor comprising contacting ethylene under polymerization conditions with a chrome catalyst system comprising a supported chromium catalyst system comprising: chromium oxide, a silica-containing support comprising silica having a pore volume of about 2.4 to about 3.7 cm 3 /g and a surface area of about 410 to about 620 m 2 /g, an alkylaluminum compound; wherein said supported chromium catalyst is activated at about 400 to about 860° C.; conducting the polymerization at a space-time-yield value of greater than 8 kg/m 3 ·h; and operating the polymerization at a catalyst productivity of greater than 3000 kg polymer/kg catalyst and at a reaction temperature at least 2.5° C. higher than the reaction temperature when polymerizing with the same chrome catalyst system in the absence of triethyl aluminum and producing the ethylene polymer at the same polymer molecular weight and density using the same space-time-yield value, ethylene partial pressure, H 2 /C 2 gas mole ratio and comonomer to C 2 gas mole ratio.