| 摘要 |
Olefins are polymerised in presence of a thermally activated, chromium-contg., supported catalyst coated with a hydrocarbon aluminate polymer (I). The support is pref. a porous inorganic oxide and pref. contains superficial OH gps. with which the Cr and Al components are reactive. The Al cpds. used improves the catalyst activity but are resistant to hydrolysis under conditions of prepn. while preserving their reactivity with the support superficial OH gps. The catalyst is partic. suitable for polymerising alpha-olefins esp. in presence of hydrogen. The catalyst pref. comprises a silica xerogel having a specific surface 200-500 m2/g and pore vol. >2 cm3/g a large proportion of the pore vol. comprising pores having dia. in the range 300-600 angstroms. The xerogel is coated with a chromium cpd. and (I) and is thermally activated in a non-reducing atmos. at a temp. from 93 degrees C to the decomposition temp. of the support, pref. 93-1093 degrees C for 2-12 hrs. |
