Influence of Silica-Supported Alkylaluminum on Heterogeneous Zwitterionic Anilinonaphthoquinone Nickel and Palladium-Catalyzed Ethylene Polymerization and Copolymerization with Polar Monomers

Abstract

The development of the heterogeneous late transition metal-catalyzed olefin (co)­polymerization is a challenge in current research. Here, we report the preparation of heterogeneous anilinonaphthoquinone nickel and palladium catalysts by the binding of SiO2-supported alkylaluminums to a quinone oxygen of the ligand (Mt-AlR 3 /SiO 2 ). The heterogeneous nickel catalyst exhibited a very high activity (up to 10.4 × 106 g mol–1 h–1) for ethylene polymerizations to produce semicrystalline high-molecular-weight (M n up to 54.3 × 104 g mol–1) polyethylenes with a low degree of branching (<11.1/1000 C), high T m values (121–131 °C), and well-regulated particle morphologies. The polymerization behavior depended on the electron density of the metal center modulated by the Lewis acidity of the remotely bound alkylaluminum as can be analyzed and verified through model optimizations and density functional theory (DFT) calculations. Most importantly, these nickel catalysts were able to produce semicrystalline ethylene/5-hexene-1-yl copolymers with a high activity and high molecular weight. The heterogeneous palladium catalyst can promote the copolymerization of ethylene with commercial methyl acrylate or polar norbornene derivatives with a moderate activity, affording a polar functionalized polyethylene and a cyclic olefin copolymer.

Dual-Site Polymeric Heterogeneous α-Diimine Ni Catalysts with Tailored Spatial Distribution for Ethylene Polymerization

“…The use of supported catalysts led to good product morphological control and avoidance of reactor fouling (Figure A). − Moreover, due to the polar polyolefin component derived from 10-undecenoic acid (containing ca. 2 wt % of polar monomer unit), the in-reactor blend resulting from the heterogeneous catalyst exhibits better hydrophilicity than the product of homogeneous polymerization (Figure B,C).…”

“…Therefore, the application of the dual-site catalysts obtained by combining different single-site molecular catalysts (Figure B) in the synthesis of polyolefin in-reactor blends has attracted more and more attention since 1980s. , These well-defined dual-site molecular catalysts make it possible to achieve better control of the polymerization reaction and to produce a broad range of polyolefins for a diverse range of applications due to a good understanding of the reaction mechanism and the relationship between the catalyst structure and the polymer structure. Heterogeneous dual-site catalysts are preferred in industry due to their product morphology control, thereby preventing reactor fouling typical of slurry and gas-phase polymerization using homogeneous systems. − Typically, a single-site catalyst can be supported on the surface of the solid particles (including the surface of the internal pores) by ions and hydrogen or covalent bonds (Figure B). − …”

“…Consequently, an interesting hypothesis is that the spatial distribution of different single-site catalysts on a mesoscopic scale in the dual-site catalyst particles (Figure C) will have a significant influence on the superstructures and properties of polyolefin in-reactor blend products. However, typical heterogenization methods support the molecular catalyst on the surface of a solid support at one time in an extensive manner without tuning the spatial distribution of different single-site catalyst components within the particles. − Some spatial distribution types, such as the core–shell type with varying radial distribution, may be difficult to obtain by typical methods because the preparation and pretreatment conditions (involving aqueous solution and high temperature) of most commonly used solid supports, such as silica, MgCl 2 , Al 2 O 3 , and silicates, are incompatible with organometallic catalysts. ,− As a result, the experimental studies on this hypothesis are a challenge.…”

Advance on nickel‐ and palladium‐catalyzed insertion copolymerization of ethylene and acrylate monomers

“…126 Heterogeneous catalyst Pd110-Al/SiO 2 (Figure 31) was further developed by introduction of Al compounds. 127 Enhanced activity (up to 30 kg copolymer/(mol Pd h)) is observed in Pd110-Al/SiO 2 system. The resultant semicrystalline EMA copolymers produced by Pd110-Al/SiO 2 catalyst have lower molecular weights (M n = 4.7-5.2 kg/mol) but with high melting temperatures (120 C) compared to those synthesized with Pd110.…”

“…The supported Pd110/SiO 2 produces EMA copolymers with higher molecular weights ( M n up to 98 kg/mol) but lower MA incorporation (0.5–0.7 mol%) than homogeneous palladium system Pd110 126 . Heterogeneous catalyst Pd110‐Al/SiO 2 (Figure 31) was further developed by introduction of Al compounds 127 . Enhanced activity (up to 30 kg copolymer/(mol Pd h)) is observed in Pd110‐Al/SiO 2 system.…”