Zirconium Hydrocarbyl Chemisorption on Sulfated Metal Oxides:New Supports,Chemisorption Pathways,and Implications for Catalysis

摘要

The sulfated metal oxides(SMOs)sulfated stannia(SnS),sulfated iron oxide(FeS),and sulfated titanium dioxide(TiS)have been synthesized and examined as support materials/cocatalysts/activators for molecule-based olefin polymerization and hydrogenation catalysis.~(13)C CPMAS NMR spectroscopic analysis of Cp2-Zr(~(13)CH_3)_2/SMO chemisorption shows that cationic zirconocenium species are formed along with varying amounts of catalytically inactive mu-oxo(Cp_2Zr(CH_3)O-surface)species,depending on the support material.Ethylene polymerization data with the supported catalysts show that polymerization activity is dependent on both precursor ligation [Zr(CH_2Ph)_4 >(Me_5Cp)ZrMe3] and the nature of the support(SnS > FeS > TiS).Poisoning studies were performed in conjunction with ethylene polymerization,mediated by(Me_5Cp)-ZrMe3 supported on each SMO,and reveal that,for(Me_5Cp)ZrMe_3/SnS,61 +-5% of the Zr sites are catalytically significant,while,for(Me_5Cp)ZrMe_3/FeS,this quantity is 22 +-2%,and for(Me_5Cp)ZrMe_3/TiS,63 +-9%.These catalysts are also active for benzene hydrogenation and are separable from liquid-phase products using physical or,in the case of FeS,magnetic techniques.