To provide, generally, processes for the production of polyolefin polymers utilizing chromium-containing catalysts with aluminum alkyls.SOLUTION: Embodiments of an invention disclosed herein relate to a process for adjusting one or more of the high load melt index (I21.6), mass average molecular mass (Mw), and molecular mass distribution (Mw/Mn) of one or more polyolefin polymers during a polymerization reaction, or for adjusting the catalyst activity of the polymerization reaction, the process including 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) moving 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 polyolefin polymers; and d) recovering the one or more polyolefin polymers.SELECTED DRAWING: None