Homogeneous nickel- and palladium-diimine catalysts polymerize ethylene to form branched polyethylene. Late transition metals are also less prone to poisoning by polar functional groups, allowing for incorporation of polar monomers in copolymerizations with polar monomers. Most industrial catalysts for olefin polymerization are heterogeneous. Applying common methods to form active heterogeneous catalysts for late metals, such as contacting a precatalyst with SiO2 functionalized with methylaluminoxane, often results in low activity. Only a few examples of active heterogeneous late metal catalysts were reported. In all cases, copolymerization chemistry was not reported. Here we describe the reaction of nickel- and palladium-diimine complexes with sulfated zirconium oxide (SZO) to form [(diimine)M(CH3)(solvent)][SZO], (M : Ni or Pd). Sulfated oxides support electrophilic surface species where the sulfate acts as a weakly coordinating anion. We characterized the isolated catalysts by solid-state NMR spectroscopy and elemental analysis which supported the formation of cationic species of the [(diimine)M(CH3)(solvent)]+ on the sulfated zirconium oxide. Titration of the nickel catalyst with ethylene indicated that most Ni-Me sites are active in ethylene polymerization. These catalysts are active in ethylene (co)polymerization. For example, under 45 psi pressure of ethylene at 40 oC, the nickel catalyst polymerizes ethylene with TOF of 21000 h-1 (586 kgPE/(molNi*h)) which is similar to the activity of homogeneous analog. High temperature NMR spectroscopy of obtained polymers and GPC analysis shows that these catalysts produce branched high molecular weight polymers having narrow polydispersity values.

Well-defined nickel- and palladium-diimine catalysts supported on sulfated zirconia for ethylene (Co)polymerization reactions

254th National Meeting (2017)

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