Patent ID: 8981021
Filing Date: 2015-03-17
Classification: C08F

Abstract:
1. A method for producing a polyolefin, the method comprising: determining an optimum operating temperature for producing a polyolefin in a fluidized bed reactor system; selecting a chromium oxide-based catalyst that has been reduced with diethyl aluminum ethoxide (DEAlE) based on desired properties of the polyolefin achieved at the operating temperature, wherein the chromium oxide-based catalyst has been reduced with the diethyl aluminum ethoxide prior to the addition of the catalyst to the reactor and wherein the molar ratio of DEAlE/Cr in the catalyst is from about 0.1 to about 10; contacting a monomer with the chromium oxide-based catalyst in the fluidized bed reactor system; cooling a recycle stream of the fluidized bed reactor system in order to maintain the optimum operating temperature; and feeding oxygen to the fluidized bed reactor system to maintain in the fluidized bed reactor system an effective amount of oxygen necessary to minimize fouling of the fluidized bed reactor system, wherein the catalyst is a chromium oxide on dehydrated silica, wherein the oxygen is fed to the fluidized bed reactor system at a rate equivalent to from greater than 0 to less than 0.02 parts per million by volume of oxygen relative to a volumetric rate of the monomer added to the fluidized bed reactor system, and wherein the optimum operating temperature is such that a highest temperature in the fluidized bed reactor system is less than about 20° C. below a melting point of the polyolefin.