Development of Single-Site New Olefin Polymerization Catalyst Systems Using MgCl2-Based Activators: MAO-Free MgCl2-Supported FI Catalyst Systems

Abstract

MAO-free new single-site catalyst systems have been developed for olefin polymerization, which are comprised of bis(phenoxy-imine) Ti, Zr, or V complexes (Ti–, Zr–, or V–FI Catalysts) and MgCl2-based compounds. These new catalyst combinations are highly active single-site (Ti–FI Catalysts), exceptionally active (Zr–FI Catalysts), or highly active, thermally robust, single-site (V–FI Catalyst) catalysts for ethylene polymerization. The catalysts can display higher catalytic performance (i.e., catalytic activity, stereoselectivity, thermal stability) than those activated by the well-established MAO activators. In addition, these catalysts are supported, and thus possess a technological advantage vis-à-vis control over polymer morphology, which is essential for commercial application. Therefore, the application of MgCl2-based compounds capable of working both as an activator and a support for non-metallocene complexes provides a conceptually new strategy for the development of high-performance supported single-site catalysts.

Titanium (IV) and Nickel (II) Catalysts Based on Anilinotropone Ligands

“…This is in sharp contrast to Ti-FI catalysts, which require steric congestion near the polymerization center in order to display high activity. The activity obtained with complex 1 (8000 Kg PE mol cat -1 h -1 ) is extremely high for a Ti complex with no cyclopentadienyl (Cp) or PI ligand(s) [16,[23][24][25][26]. In fact, the activity exceeds that displayed by Ti-FI catalyst 10 under analogous conditions (3480 Kg PE mol cat -1 h -1 ) ( Figure 2) [22].…”

“…Accordingly, to obtain a highly active catalyst, the existence of ligands with a notable balance between their electron donating and withdrawing, evidenced by calculation of energy gap between the HOMO (the highest occupied molecular orbital) and LUMO (the lowest unoccupied molecular orbital) of them, is a predominate requirement [22]. For comparison, the energy gap between the HOMO and LUMO of three well-known ligands, namely phenoxy-imine [15,[23][24][25][26][27][28][29], pyrrolide-imine [15,[27][28][29], indolideimine [30] and the new aminotropone chelate ligand [19] was studied using densityfunctional theory (DFT). Because of the reasonable energy gap between the HOMO and LUMO of aminotropone (2.6 eV), it was theoretically offered as a fundamentally active ligand (Scheme 2).…”

“…Unlike Ti-FI catalysts, which require sterically demanding substituents in ortho position to the phenoxy oxygen atom in order to exhibit high ethylene polymerization activity [23][24][25][26], the activity of bis(pyrrolideimine) Ti catalysts (Ti-PI) decreases with more congestion adjacent to the anionic N of the PI ligand because there is not enough space for monomer insertion [16]. The steric bulk in Ti-FI catalysts is thought to afford effective ion separation between the cationic active species and an anionic co-catalyst, resulting in enhancement of the catalytic activity.…”

FI Catalyst for Polymerization of Olefin

“…The cocatalysts for bis(phenoxy-imine)Zr and Ti complexes are generally MAO (methylaluminoxane), i-Bu3Al/Ph3CB(C6F5)4 [64,79,89], or MgCl2-based activators [73]. There has been few report on common alkylaluminums alone as cocatalyst in the catalytic system of bis(phenoxy-imine)Zr and Ti complexes, they used some alkylaluminums, such as triethylaluminum (Et3Al), trihexylaluminum (He3Al), or trimethylaluminum (Me3Al), could activate bis(phenoxy-imine)Zr and Ti complexes for ethylene polymerization without MAO or Ph3CB(C6F5)6, It is found that only the alkylaluminum with three linear alkyls can activate catalyst.…”

Heterogeneous Ziegler–Natta catalysts with various sizes of MgCl2 crystallites: synthesis and characterization

“…An amount of Our procedure for synthesizing the Ziegler-Natta PE catalyst followed a typical industrial procedure that can be found in patented literature [17], and it also resembles procedures described in other publications [18,19] and to some extent the recipe provided by Wang et al [20]. The carrier synthesis described by Nakayama et al [21] is an example of a support material preparation that resembles the recipe used in this study. The carrier material produced for the immobilization of homogeneous catalysts, described by Severn et al also has a composition corresponding to the support material produced in our study [22].…”