Recent progress in immobilization of late-transition-metal complexes with diimine ligands for olefin polymerization

Abstract

Late-transition-metal (LTM) catalysts are a family of very flexible ethylene polymerization catalysts because their catalytic performance can be easily adjusted by modifying the ligand structure. Their less oxyphilicity character, which may promote the production of copolymers from ethylene and polar comonomers, is another aspect that attracts much attention in both academic and industrial fields. The immobilization of LTM catalysts on spherical supports is a crucial step prior to their use in the industrial processes of gas-phase or slurry polymerizations. This paper reviews recent developments in supported LTM catalysts for olefin polymerization, and summarizes loading methods and mechanisms of the immobilization of LTM catalysts on inorganic, organic, and inorganic-organic materials, and the effects of immobilization on catalytic activity, polymerization mechanism, and polymer morphology. [22,23] are applied to olefin polymerization. The products obtained using such catalysts can be changed from polyethylene (PE) to oligomers by tuning the steric and electronic properties of the ligands [24]. Bulky complexes can produce high-molecular-weight branched PE, without the addition of α-olefin comonomers, in the presence of methylaluminoxane (MAO). Some bulky catalysts with special backbone such as camphyl and acenaphthyl show highly thermal stability and good control ability for olefin polymerization [25]. Late transition-metals are more suitable for the copolymerization of ethylene with commercial polar olefins because of their better tolerance of polar functional groups. Only amorphous polymers can be obtained if the polymerization is catalyzed by homogeneous catalysts, inevitably leading to reactor fouling in industrial units. To meet the requirements of continuous industrial gas-phase or slurry polymerization units, a crucial step for the industrialization of LMT catalysts is the immobilization of such catalysts on spherical supports to obtain morphologically uniform polymer particles. late-transition-metal complexes, diimine, immobilization, olefin polymerization

Neutral Nickel Catalysts for Olefin Homo- and Copolymerization: Relationships between Catalyst Structures and Catalytic Properties

“…Furthermore, with the advent of efficient binuclear catalysts and phosphine–sulfonate palladium catalysts, some useful concepts have been introduced to nickel systems, leading to unique catalyst properties and new polymer structures. Given all of these developments in fundamental aspects and in the immobilization of homogeneous olefin polymerization catalysts, which is crucial to preventing reactor fouling and facilitating continuous operations in industrial gas-phase and slurry processes, − we believe that the practical use of these less expensive and highly active catalysts is rather promising.…”

Immobilization of α-diimine nickel (II) catalysts on multi-walled carbon nanotube for slurry ethylene polymerization

“…Review on recent progress in immobilization of late transitional metal complexes with diimine ligands [16] reveals that these complexes have been supported on silica, magnesium chloride, molecular sieves, silicates, polystyrene, and polyhedral oligomeric silsesquioxane. But, to the best of our knowledge, there is no report on direct α-diiminonickel complex immobilization over MWCNT prior to reactor injection and on how this heterogenization technique can influence the catalytic behavior of these systems for ethylene polymerization.…”