Commercial Perspective on New Developments in Catalysis for Olefin Polymerization

Olefin polymerization catalysis is a domain of major research activity. For the last decade, much of this research has been focused in the area of metallocene catalysis, which has been at the front line in driving important technology renewal in the polyolefins industry. Developments in metallocene catalysis have instigated much trade press discussion, and now emerging nonmetallocene catalyst systems are adding new scope to the industry dialog. Announcements continue to flow in the trade press about the industry’s latest new catalyst discoveries. Hetero-substituted cyclopentadiene ligands coordinated with conventional Group IV metals; sterically-hindered, nitrogen-containing ligands coordinated with a variety of transition metal centers, including late transition metals such as Fe, Co, Ni, and Pd; and other heteroatom-based transition metal complexes have been shown to be activated with alumoxanes to form catalytic species that polymerize olefins to various types of polymers. These laboratory developments illustrate, once again, the ever-widening range of catalytic systems for olefin polymerization. This paper will offer some limited commercial perspective on new catalyst developments using the context of possible business significance to the polyethylene industry. Since some of these developments are barely out of the laboratory, it’s pretty early to be writing to provide “commercial perspective” on these systems. The only way that I could conceive to address this subject was to offer some insights on what has been learned from the ongoing development and commercialization of metallocene technology for polyethylene manufacture. I would expect some of these commercialization learnings to anticipate what will be encountered with other new catalyst systems. The commercial perspective I hope to offer will speak both to factors influencing the size of the “commercial prize” and to challenges affecting the timeline for reaching the marketplace and capturing a piece of this “commercial prize.” INTRODUCTION The family tree of ligand-based catalysts is growing. Figure 1 shows a schematic of this enlarging family tree with new structures moving well beyond the metallocene domain of cyclopentdienyl-containing systems. Symmetric and assymetric structures, bridged and unbridged, chiral and achiral catalysts are represented. In all these systems, the ligand structure, metal center, and activation chemistry define the electronic and steric environment at the active site of the catalyst and, in turn, establish the catalyst’s regulation of the stochastic processes of monomer/comonomer insertion (stereospecific or non-stereospecific) and various chain transfer chemistries. In Figure 1, metallocenes represent one very large, important category of ligand-based catalysts. Metallocene catalysis represents a very broad and very rich technology. There are an enormous number of potential catalyst systems. Some of these catalysts have progressed through the innovation pipeline from research through development to reach the arena of full-scale product commercialization. The new non-metallocene, ligand-based catalyst structures outlined in Figure 1 represent, for the most part, developments that are still quite far upstream, inside the innovation process, and are still undergoing laboratory scoping studies. The general capabilities of these new chemistries, let alone their unique capabilities, are not yet fully understood. It will be the unique performance capabilities of these catalysts that will determine their commercial significance to our industry.