Patent ID: 11859041
Assignee: CHEVRON PHILLIPS CHEMICAL COMPANY LP
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C  G | IPC C  G

Claim 22:
23. A catalyst system for polymerizing olefins, comprising:
a Group 4 metallocene olefin polymerization catalyst designed according to a method comprising:
(a) selecting a first metallocene catalyst framework comprising a Group 4 metal bonded to a hydrocarbyl ligand and to one or two independently selected substituted or unsubstituted η5-cycloalkadienyl ligands, and generating a first ground state model structure (GSA) derived from the first metallocene catalyst framework;
(b) generating (1) a first transition state model structure (TSA1) derived from migratory insertion of an ethylene molecule into a metal-hydrocarbyl ligand bond of the first metallocene catalyst framework and (2) a second transition state model structure (TSA2) derived from migratory insertion of an α-olefin co-monomer molecule into the metal-hydrocarbyl ligand bond of the first metallocene catalyst framework;
(c) determining, by at least one processor of a device, relative energies of each of the first ground state model structure (GSA), the first transition state model structure (TSA1), a dispersion energy (Disp EA1) associated with TSA1, the second transition state model structure (TSA2), and a dispersion energy (Disp EA2) associated with TSA2, and determining values for ΔG‡A1 (TSA1−GSA), ΔG‡A2 (TSA1−GSA), ΔΔG‡A (TSA2−TSA1), and an absolute difference in dispersion energies |ΔDisp EA| calculated as |Δ(Disp EA2−Disp EA1)| for migratory insertion of the ethylene molecule versus the α-olefin co-monomer molecule in the first metallocene catalyst framework;
(d) repeating steps (a)-(c) using a second metallocene catalyst framework comprising the Group 4 metal bonded to the hydrocarbyl ligand and to the one or two independently selected η5-cycloalkadienyl ligands, wherein at least one of the η5-cycloalkadienyl ligands comprises a first test substituent, and generating a corresponding second ground state model structure (GSB), third transition state model structure (TSB1), and fourth transition state model structure (TSB2), and determining, by at least one processor of a device, relative energies of each of a GSB, TSB1, a dispersion energy (Disp EB1) associated with TSB1, TSB2, and a dispersion energy (Disp EB2) associated with TSB2, and determining values for ΔG‡B1 (TSB1-GSB), ΔG‡B2 (TSB2-GSB), ΔΔG‡B (TSB2−TSB1), and an absolute difference in dispersion energies |ΔDisp EB| calculated as |Δ(Disp EB2−Disp EB1)| for migratory insertion of the ethylene molecule versus the α-olefin co-monomer molecule in the second metallocene catalyst framework; and
(e) identifying the first test substituent of the second metallocene catalyst framework as (1) enhancing α-olefin co-monomer incorporation into a polyethylene co-polymer relative to the first metallocene catalyst framework when ΔΔG‡B<ΔΔG‡A, when |ΔDisp EB|>|ΔDisp EA|, or a combination thereof, or (2) enhancing ethylene incorporation into a polyethylene co-polymer relative to the first metallocene catalyst framework when ΔΔG‡B>ΔΔG‡A, when |ΔDisp EB|<|ΔDisp EA|, or a combination thereof;
wherein the Group 4 metal is bonded to the hydrocarbyl ligand and to the one or two independently selected substituted or unsubstituted η5-cycloalkadienyl ligands;
wherein at least one of the η5-cycloalkadienyl ligands comprises the first test substituent which is identified as enhancing olefin co-monomer incorporation into a polyethylene co-polymer, relative to an olefin co-monomer incorporation of the first metallocene catalyst framework, and
wherein the first metallocene catalyst framework comprises the following structure:,