Effect of “topotactic” reduction product of tungsten disulfide on catalytic activity of metallocene catalyst for olefin polymerization

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2004-02, Vol.208 (1), p.55-65
• Main Authors: Yamada, Satoru, Yano, Akihiro, Sato, Morihiko, Itoh, Takahito
• Format: Article
• Language: English
• Subjects: Catalysis; Catalytic reactions; Chemistry; Cocatalyst; Exact sciences and technology; General and physical chemistry; Metallocene catalyst; N,N-Dimethylanilinium salt; Polymerization; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Topotactic reduction; Tungsten disulfide
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2003.07.011

Addition of N, N-dimethylanilinium ion (Ph(Me) 2NH +) intercalated WS 2 as a cocatalyst to Ind 2ZrCl 2/Et 3Al was found to improve significantly the catalytic activity for ethylene polymerization. It was proposed that neutral dialkylmetallocene was protonated by Ph(Me) 2NH + in the interlayer space of WS 2, especially on the surface of the cocatalyst, to form the cationic monoalkylmetallocene and that the two-dimensional macroanion of WS 2 functioned as a non-coordinating anion and a carrier for the cationic species. N, N-Dimethylanilinium (Ph(Me) 2NH +) salt of tungsten disulfide (WS 2) was developed as a novel cocatalyst for metallocene catalysts. The cocatalyst is composed of N, N-dimethylanilinium ion as a cationic part and “topotactic” reduction product of WS 2, obtained by acquisition of an electron by the neutral host lattice of WS 2 without structural alteration, as an anionic part. Notable improvement of the catalytic activity for ethylene polymerization using the bis(indenyl)zirconium dichloride (Ind 2ZrCl 2)/triethylaluminum (Et 3Al) catalyst was observed upon the addition of the Ph(Me) 2NH + salt of WS 2. The addition of the corresponding molybdenum disulfide (MoS 2) one that had smaller crystallite size than the Ph(Me) 2NH + salt of WS 2 showed the lower catalytic activity. The resultant poly(ethylene) prepared by the Ind 2ZrCl 2/Et 3Al/Ph(Me) 2NH + salt of WS 2 possessed similar properties like narrow polydispersity to that prepared by conventional metallocene type catalysts. The Zr loadings on the precipitate of the Ind 2ZrCl 2/Et 3Al catalyst activated by the Ph(Me) 2NH + salt of WS 2 increased with a decrease in the crystallite size of the Ph(Me) 2NH + salt of WS 2. However, the catalytic activities in ethylene polymerization decreased drastically, indicating that the decrease of the crystallite size led to the significant increase of inactive species for ethylene polymerization.