Research Center, Mitsui Chemicals, Inc., Japan.
Acc Chem Res. 2009 Oct 20;42(10):1532-44. doi: 10.1021/ar900030a.
Catalysts contribute to the efficient production of chemicals and materials in almost all processes in the chemical industry. The polyolefin industry is one prominent example of the importance of catalysts. The discovery of Ziegler-Natta catalysts in the 1950s resulted in the production of high-density polyethylenes (PEs) and isotactic polypropylenes (iPPs). Since then, further catalyst development has led to the production of a new series of polyolefins, including linear low-density PEs, amorphous ethylene/1-butene copolymers, ethylene/propylene/diene elastomers, and syndiotactic PPs (sPPs). Polyolefins are now the most important and the most produced synthetic polymers. This Account describes a family of next-generation olefin polymerization catalysts (FI catalysts) that are currently being used in the commercial production of value-added olefin-based materials. An FI catalyst is a heteroatom-coordinated early transition metal complex that combines a pair of nonsymmetric phenoxy-imine [O(-), N] chelating ligands with a group 4 transition metal. The catalytically active species derived from FI catalysts is highly electrophilic and can assume up to five isomeric structures based on the coordination of the phenoxy-imine ligand. In addition, the accessibility of the ligands of the FI catalysts and their amenability to modification offers an opportunity for the design of diverse catalytic structures. FI catalysts exhibit many unique chemical characteristics: precise control over chain transfers (including highly controlled living ethylene and propylene polymerizations), extremely high selectivity for ethylene, high functional group tolerance, MAO- and borate-free polymerization catalysis, significant morphology polymer formation, controlled multimodal behavior, high incorporation ability for higher alpha-olefins and norbornene, and highly syndiospecific and isospecific polymerizations of both propylene and styrene. These reactions also occur with very high catalyst efficiency. The reaction products include a wide variety of unique olefin-based materials, many of which were previously unavailable via other means of polymerization. We have produced selective vinyl- and Al-terminated PEs, ultrahigh molecular weight linear PEs, regio- and stereoirregular high molecular weight poly(higher alpha-olefin)s, ethylene- and propylene-based telechelic polymers, a wide array of polyolefinic block copolymers from ethylene, propylene, and higher alpha-olefins, and ultrafine noncoherent PE particles. FI catalysts are important from the organometallic, catalytic, and polymer science points of view, and the chemical industry is now using them for the production of value-added olefin-based materials. We anticipate that future research on FI catalysts will produce additional olefin-based materials with unique architectures and material properties and will offer scientists the chance to further study olefin polymerization catalysis and related reaction mechanisms.
催化剂在几乎所有化学工业过程中都有助于化学品和材料的高效生产。聚烯烃工业是催化剂重要性的一个突出例子。20 世纪 50 年代发现的齐格勒-纳塔催化剂导致了高密度聚乙烯（PE）和等规聚丙烯（iPP）的生产。此后，进一步的催化剂开发导致了一系列新型聚烯烃的生产，包括线性低密度聚乙烯、无定型乙烯/1-丁烯共聚物、乙烯/丙烯/二烯弹性体和间规聚丙烯（sPP）。聚烯烃现在是最重要和产量最大的合成聚合物。本说明描述了一类目前正在用于商业生产增值烯烃基材料的下一代烯烃聚合催化剂（FI 催化剂）。FI 催化剂是一种杂原子配位的早期过渡金属络合物，它将一对非对称的酚氧基-亚胺[O（-），N]螯合配体与第四族过渡金属结合在一起。源自 FI 催化剂的催化活性物质具有很强的亲电性，并且可以根据酚氧基-亚胺配体的配位假设多达五种异构结构。此外，FI 催化剂的配体的可及性及其可修饰性为设计各种催化结构提供了机会。FI 催化剂具有许多独特的化学特性：对链转移的精确控制（包括高度受控的乙烯和丙烯聚合）、对乙烯的极高选择性、高官能团耐受性、无 MAO 和硼酸聚合催化、显著的形态聚合物形成、控制多模态行为、对更高的α-烯烃和降冰片烯的高掺入能力、以及丙烯和苯乙烯的高度间规和等规聚合。这些反应的催化剂效率也非常高。反应产物包括各种独特的基于烯烃的材料，其中许多以前无法通过其他聚合方法获得。我们已经生产了选择性的乙烯基和 Al 端基 PE、超高分子量线性 PE、区域和立体不规则的高分子量聚（高α-烯烃）、乙烯和丙烯基遥爪聚合物、一系列来自乙烯、丙烯和高α-烯烃的聚烯烃嵌段共聚物以及超细非相干 PE 颗粒。FI 催化剂从有机金属、催化和聚合物科学的角度来看都很重要，而且化工行业现在正在使用它们来生产增值的烯烃基材料。我们预计，对 FI 催化剂的未来研究将产生具有独特结构和材料性能的其他基于烯烃的材料，并为科学家提供进一步研究烯烃聚合催化和相关反应机制的机会。
