Olefin Upgrading Catalysis by Nitrogen-based Metal Complexes I State
Olefin Upgrading Catalysis by Nitrogen-based Metal Complexes provides a critical review of the state-of-the-art developments in industrially relevant processes connected to efficient and selective olefin upgrading. Specific attention is devoted to catalys
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Cr Complexes of Nitrogen Donor Ligands for Olefin Oligomerisation and Polymerisation David S. McGuinness
Abstract Chromium complexes continue to play an important role as catalysts for olefin oligomerisation and polymerisation, with many of these catalysts supported by N-donor containing ligation. A number of highly active catalysts for ethylene polymerisation have been developed in recent years, as well as new catalysts for highly selective ethylene oligomerisation. New developments in this area since 2003, in which chromium complexes of N-donor ligands are utilized, are discussed in subsequent sections.
1.1 Introduction The oligomerisation and polymerisation of olefins to higher oligomers and polymer continues to receive a high level of research interest, both within industry and academia [1, 2]. The most important industrial products resulting from these processes are ethylene oligomers (linear a-olefins) and polyethylene plastics, so it is of no surprise that the vast majority of studies detailed below make use of ethylene as the monomer. Chromium catalysts occupy an important position in this field. The heterogeneous Phillips catalyst (Cr/SiO2) is used to produce a large proportion of global polyethylene supplies [3], while homogenous chromium catalysts have been utilized for selective production of 1-hexene and 1-octene from ethylene [4]. As such, there has been much interest in the development of new chromium based catalysts for oligomerisation and polymerisation, with many of these new systems supported by N-donor ligation. As can be seen below, the most common linkage is an imine donor, although examples of amine and amido donors are also detailed. D. S. McGuinness (&) School of Chemistry, University of Tasmania, Private Bag 75, Hobart 7000, Australia e-mail: [email protected]
G. Giambastiani and J. Cámpora (eds.), Olefin Upgrading Catalysis by Nitrogen-based Metal Complexes I, Catalysis by Metal Complexes, 35 DOI: 10.1007/978-90-481-3815-9_1, Ó Springer Science+Business Media B.V. 2011
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D. S. McGuinness
Non-metallocene polymerisation catalysts, including chromium systems, were reviewed in 2003 [1], while selective oligomerisation with chromium catalysts was reviewed in 2004 [4]. As such, the coverage herein focuses on developments which occurred after this period. Nonetheless, some reference to the older literature is made where required to provide a background to new work. The vast majority of systems described below are precatalysts which require activation with a cocatalyst; this is almost always MAO or another alkylaluminium reagent [5]. Wherever possible, activities for ethylene polymerisation have been calculated in terms of kg(product) mol(cat)-1 bar(ethylene)-1 h-1 (kg mol-1 bar-1 h-1). In keeping with previous reviews [1, 6], the following descriptors of activity have been used, bearing in mind the limitations of comparing different systems under different conditions and differing degrees of optimisation: very high ([1,000); high (1,000–100); moderate (100–10); low (10–1); v
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