Polymerization Processes Utilizing Chromium-Containing Catalysts

Embodiments of an invention disclosed herein relate to a process for adjusting one or more of the high load melt index (I21.6), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) of one or more of polyolefin polymers during a polymerization reaction or adjusting the catalyst activity of the polymerization reaction, the process includes a) pre-contacting at least one chromium-containing catalyst with at least one aluminum alkyl to form a catalyst mixture outside of a polymerization reactor; b) passing the catalyst mixture to the polymerization reactor; c) contacting the catalyst mixture with one or more monomers under polymerizable conditions to form the one or more of polyolefin polymers; and d) recovering the one or more of polyolefin polymers.