Controlling reactor split and a product parameter

A non-transitory computer-readable storage medium comprising instructions to control reactor split and a product parameter of polyethylene product in a multimodal polymerization reaction that when executed by a processor are to:

• a) polymerize at least one monomer in a gas phase reactor in the presence of a supported catalyst comprising at least two different catalyst compounds to form a multimodal polyethylene product having a reactor split equal to respective weight fractions of resin components in the polyethylene product;
• b) apply a predetermined formula for flow index of the multimodal polyethylene product;
• c) obtain incorporation data and production rate data from the reaction based upon the predetermined formula;
• d) determine an actual hydrogen leading indicator;
• e) compare the actual hydrogen leading indicator to a target value for a hydrogen leading indicator to determine a deviation of the actual hydrogen leading indicator from the target value for the hydrogen leading indicator;
• and
• f) adjust an amount of a catalyst precursor for forming at least one of the two different catalyst compounds and being fed to the gas phase reactor to control reactor split equal to respective weight fractions of resin components in the polyethylene product and the product parameter of the polyethylene product wherein the catalyst precursor is activated and forms at least one of the catalyst compounds of the supported catalysts in the gas phase reactor and wherein the adjusted amount of catalyst precursor is based upon data obtained in c) and the deviation determined in e).