Supported Single-Site Organometallic Catalysts for the Synthesis of High-Performance Polyolefins

Single-site organometallic catalysts supported on solid inorganic or organic substrates are making an important contribution to heterogeneous catalysis. Early and late transition metal single-site catalysts have changed the polyolefin manufacturing industry and research with their ability to produce polymers with unique properties. Moreover, several of these catalysts have been commercialized on a large scale. Their heterogenization for slurry or gas phase olefin polymerization is important to produce polyolefin as beads and to avoid reactor fouling. The large majority of supports currently used in industry are inorganic materials (SiO2, Al2O3, MgCl2), with silica being the most important. Single-site supported catalysts are most commonly prepared by molecular-level anchoring/chemisorption, in which a molecular precursor undergoes reaction with the surface while maintaining most of the ligand sphere of the parent molecule. Chemisorption of discrete organometallic complexes on solid supports yields catalysts with well-defined active sites, greater thermal stability than the homogeneous analogues, and decreased reactor fouling versus the homogeneous analogues. This review presents a detailed account of the synthesis, characterization and polymerization properties of single-site catalysts supported on metal oxides and metal sulfated oxides, primarily carried out at Northwestern University. Early and late transition metal single-site catalysts supported on inorganic surfaces have changed the polyolefin research and production with their unique ability to produce polymeric materials with unique architectures. This review presents a detailed account of the synthesis, characterization, and polymerization properties of single-site catalysts supported on metal oxide surfaces.