A method of forming a modified precursor composition of a Ziegler-Natta (ZN) catalyst, comprising: providing a precursor composition of the ZN catalyst for treatment with an aluminum alkyl compound in a liquid organic solvent, where the precursor composition of the ZN catalyst includes at least one titanium compound, wherein providing the precursor composition includes precipitating at least one magnesium compound with the at least one titanium compound on a carrier material; treating the at least one titanium compound in the precursor composition with the aluminum alkyl compound in the liquid organic solvent, where the aluminum alkyl compound converts the at least one titanium compound in the precursor composition into a modified state of the ZN catalyst; and removing at least a portion of the aluminum alkyl compound and reaction by-product compounds in the liquid organic solvent not consumed in converting the at least one titanium compound in the precursor composition into the modified state from the precursor composition to form the modified precursor composition of the ZN catalyst; where precipitating the at least one magnesium compound with the at least one titanium compound on the carrier material includes: dissolving the at least one magnesium compound and the at least one titanium compound in a mole ratio of 3:1 to 5:1 (mole of the at least one magnesium compound: mole of at least one titanium compound) in tetrahydrofuran to form a Magnesium compound/Titanium compound solution; mixing the carrier material in the Magnesium compound/Titanium compound solution; and removing the tetrahydrofuran to form the precursor composition of the ZN catalyst. providing a precursor composition of the ZN catalyst for treatment with an aluminum alkyl compound in a liquid organic solvent, where the precursor composition of the ZN catalyst includes at least one titanium compound, wherein providing the precursor composition includes precipitating at least one magnesium compound with the at least one titanium compound on a carrier material; treating the at least one titanium compound in the precursor composition with the aluminum alkyl compound in the liquid organic solvent, where the aluminum alkyl compound converts the at least one titanium compound in the precursor composition into a modified state of the ZN catalyst; and removing at least a portion of the aluminum alkyl compound and reaction by-product compounds in the liquid organic solvent not consumed in converting the at least one titanium compound in the precursor composition into the modified state from the precursor composition to form the modified precursor composition of the ZN catalyst; where precipitating the at least one magnesium compound with the at least one titanium compound on the carrier material includes: dissolving the at least one magnesium compound and the at least one titanium compound in a mole ratio of 3:1 to 5:1 (mole of the at least one magnesium compound: mole of at least one titanium compound) in tetrahydrofuran to form a Magnesium compound/Titanium compound solution; mixing the carrier material in the Magnesium compound/Titanium compound solution; and removing the tetrahydrofuran to form the precursor composition of the ZN catalyst. dissolving the at least one magnesium compound and the at least one titanium compound in a mole ratio of 3:1 to 5:1 (mole of the at least one magnesium compound: mole of at least one titanium compound) in tetrahydrofuran to form a Magnesium compound/Titanium compound solution; mixing the carrier material in the Magnesium compound/Titanium compound solution; and removing the tetrahydrofuran to form the precursor composition of the ZN catalyst. <EOS>