Influence of Internal Donors on the Performance and Structure of MgCl₂ Supported Titanium Catalysts for Propylene Polymerization

Abstract

An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal donors, differing in coordination nature on the structural aspects of MgCl2 matrix in high‐performance MgCl2‐supported titanium catalysts was developed using FTIR spectroscopy and WAXD studies. The analysis of the >CO stretching IR band of internal donors showed their coordination to (104) and (110) lateral cuts of MgCl2 matrix. Transformation of magnesium ethoxide {Mg(OEt)2} to MgCl2 during catalyst preparation resulted in different MgCl2 phases, namely the α‐form, β‐form, and the disordered δ‐form, which were analyzed by WAXD studies. The results from WAXD showed the relative preference of α‐form over β‐form in case of DIBP‐based catalysts, which might be due to interlayer bridging between adjacent layers due to the bidendate nature of DIBP. This can be one of the reasons for the high productivity of dialkyl‐phthalate‐based catalysts in comparison to ethyl‐benzoate‐based catalyst systems.magnified image

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

“…prepared support material with a thickness of 28 Å, Chien et al [48] produced a ballmilled catalyst with a crystal thickness of 36 Å, Busico et al [28] prepared a PP catalyst with a crystal thickness of 130 Å, Singh et al [49] synthesized a similar kind of catalyst with a crystal thickness of 31 Å, and Kojoh et al [50] described their use of TiCl 4 to hinder MgCl 2 from forming larger crystals in precipitation reactions.…”

Immobilization of Titanium Tetrachloride on Mixed Support of MgCl2 · xEB/Poly(methyl acrylate-co-1-octene): Catalyst for Synthesis of Broad MWD Polyethylene

“…The highly diffused WAXD pattern is indicative of the rotational disorder of MgCl 2 triple layers. In comparison with a-MgCl 2 phase, the (003) peak corresponding to the interlayer distance has shifted from 2h & 15 to 2h & 10.5, representing increase in the distance of triple layers which is attributed to the intercalation by EB [7]. The SEM image shows the presence of needle like fibers with diameter *100 nm.…”

“…Ethyl benzoate and ethoxide content (determined as ethanol) by gas chromatography (GC) analysis [7]. For other instrumental analysis, procedures as reported in …”

“…Generally inorganic compounds specifically magnesium chloride and its alkoxide derivatives are used as precursor for the active support [3][4][5][6][7]. The support generates active sites for polymerization by dispersing the immobilized transition metal species onto it.…”

Stabilized polypropylene synthesis using supported titanium catalyst system in presence of phenolic compounds

“…[1][2][3][4][5] Major improvement in catalyst technology is centered on development of shape-and size-controlled magnesium dichloridesupported titanium catalyst using internal and external donor modifications. [6][7][8][9][10][11][12] These catalyst systems produce polypropylene and its copolymer resin using slurry, bulk, and gas phase polymerization technology with high productivity, controlled stereospecificity, and improved morphological characteristics.…”