Constrained geometry homogeneous catalysts

In homogeneous polymerization catalysis (see Kaminsky Catalysts), constrained-geometry (CG) catalysts differ from bis Cp metallocenes in their ability to readily incorporate a-olefins in copolymerization with ethylene. This ability is due to the open nature of the catalyst active site. 

A review of the most cited U.S. patents in the polyolefins field as of August 2006, gives an indication of the most important patents in this fast-developing field. The two patents by Lai et al. (U.S. 5,272,236 and 5,278,272) are the two most cited patents in the field of polyolefins (553 and 445 citations, respectively) and these two patents survived opposition worldwide. The third most cited patent (389 citations) in the polyolefins area is by Stevens and Neithamer of The Dow Chemical Company, describing constrained geometry catalyst systems for producing homogeneous polyethylene. The fourth and fifth most cited U.S. patents in this field are ExxonMobil Chemical s U.S. 

Deposition of paRmt on the constrained geometry catalyst technology (CGCT) based on the transition metals, M = Ti, Zr, Hf. The resulting PO is substantially linear. The preferred composition comprises 10-95 wt% of homogeneously branched linear a-olefin copolymta (p = 0.930-0.965 g mL ", MWD = 1.8-2.8, single r )... 

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