Highly Flowable Nano TiO2/Porous Organic Polymer (POP) Supports for Efficient Metallocene Catalysts

Abstract

Porous organic polymers (POPs) have proven to be an efficient support in the olefin polymerization catalyst field. In this paper, nano TiO2 beads were used to modulate the pore structure, bulk density, and surface morphology and flowability of the prepared POPs. With the incorporation of the hydrophilic nano TiO2 beads, the prepared TiO2/POP supports obtained reasonable specific surface area (100–300 m2/g) and higher bulk density (0.26–0.35 g/mL) and flowability than the pure POP supports. The results show that bulk density of the prepared TiO2/POP particles increased when adding an increased amount of TiO2, and when 37.5% TiO2 (weight percent to the total comonomers divinylbenzene (DVB) and 2-hydroxyethyl methacrylate (HEMA)) and 3:1 DVB/HEMA (molar ratio) were added, highly flowable TiO2/POP composites (POP-6 and POP-7) were obtained. With the modulation of the nano TiO2 template during the support synthesis, the prepared POP-7 particles successfully achieved a normal distribution with a narrow particle size distribution (PSD) of 0.717 and average particle size of 24.1 m, a specific surface area (SSA) of 279 m2/g, and relatively high bulk density of 0.30 g/mL. Furthermore, all the prepared TiO2/POP supports obtained higher ethylene polymerization activity than silica gel-supported commercial metallocene catalyst. The immobilized (n-BuCp)2ZrCl2/MAO@POP-7 catalyst exhibited the highest ethylene polymerization activity of 4794 kg PE/mol Zr.bar.h and productivity of 389 g PE/g cat, more than twice that of the commercial counterpart. Even higher catalyst productivity (3197 g PE/g cat) and bulk density of the produced PE (0.36 g/mL) could be obtained in higher ethylene partial pressure at 80 ∘C for 2 h, and the prepared TiO2/POP catalyst shows no obvious Zr+ active sites decay during the ethylene polymerization.

Porous Organic Polymers-Supported Zeigler-Natta Catalysts for Preparing Highly Isotactic Polypropylene with Broad Molecular Weight Distribution

“…As seen from Table 1 , POP3100 achieved a high specific surface area (SSA) of 397 m 2 /g with a low bulk density of 0.14 g/cm 3 , which will lead to low bulk density of the immobilized catalyst and the prepared polymer due to the replication effect. In order to improve the bulk density and flowability of the prepared POP support, titanium oxide nanoparticles were incorporated as a template according to our previous work [ 38 ], and a reasonable SSA of 272 m 2 /g and total pore volume (PV) of 0.216 cm 3 /g was obtained with a higher bulk density of 0.28 g/cm 3 and excellent particle flowability. As illustrated in Figure 1 , the isotherm curves of nitrogen sorption showed the porous structure of the prepared porous organic polymer, and the pore size of the prepared two POPs were mainly focused in the range from 1 to 4 nm.…”

“…In the dispersion polymerization, the thermodynamic compatibility between the solvent and the prepared polymers, the type and content of the selected functional comonomers, cross-linking degree, template agent, etc., as discussed in detail in our previous work, play a key role in the properties of the prepared POP as catalyst support [ 26 , 38 ]. To obtain relatively excellent properties (high SSA and bulk density, good particle flowability, etc.)…”

“…In our recent work, 4-vinylbenzenesulfonic acid sodium was selected as the functional comonomer in the synthesis of POP, and the sulfonated POP-based Ziegler–Natta PP catalysts exhibited excellent stereoselectivity [ 34 ], although the produced PP particles obtained relatively low bulk density due to the sulfonated POP support. Highly flowable POPs with relatively high bulk density were also reported by our group, and the POP-based metallocene catalyst exhibited excellent polymerization activities, polymer physical properties and industrialization potential [ 38 ].…”

Immobilized Polyolefin Catalysts: Organic Versus Inorganic Supports

“…By selection of appropriate solvent(s) with matched thermodynamic solubility with used comonomer and the prepared polymer, template agent, functional monomer and cross ling agent content, the synthesis of eligible POPs which meet the requirement as the commercial polyolefin catalysts supports would be practicable, and POPs with high surface area, good surface morphology and high bulk density were prepared. In another attempt, highly flowable nano TiO 2 / POPs hybrid supports with reasonable pore structure and surface morphology were synthesized and the prepared metallocene catalysts exhibited higher ethylene polymerization activity than inorganic silica supports with no obvious activity decay for 2 hours [20]. This inorganic-organic hybrid approach proved to be an efficient way to overcome the drawbacks, and will surely benefit to facilitate the industrialization of POPs in olefin catalysis.…”

Ionic Liquid-Modified Porous Organic Polymers as Efficient Metallocene Catalyst Supports

“…Inorganic supports, represented by SiO 2 , Al 2 O 3 and zeolite with hard surface and massive acidic groups, may cause a problem of deactivation and high cocatalyst costs [8][9][10][11][12][13][14][15][16]. In comparison, kinds of soft organic supports such as polystyrene, polysiloxane and POPs [17][18][19][20][21][22][23] provide an analogous environment to homogeneous polymerization and could be used without complex pre-treatment [24]. A series of functionalized POPs with tunable pore structures were synthesized by our team, they showed better catalytic activity than silica supports, and can be optimized by changing the functional comonomer for better immobilization, introducing metal oxide templates and altering the solvent to acquire well-shaped particles.…”