Olefins polymn catalyst - consisting of chromium oxide deposited on two silica supports with different pore volumes/sizes

摘要

Olefins polymsn catalyst consists of (I) chromium oxide in a silica gel support having a pore volume of 2.00-3.00 pref. 2.5-3.00 cm3/g, most of the pores having a dia. of 200-600 pref. 300-600A, and a specific surface of 200-500 m2/g, and (II) chromium oxide on a silica gel support having a lower pore volume than that used in I, the major part of its pores having a smaller dia. than support I. Gives mixed polymers with good physical properties, esp. a high resistance to environmental stress cracking. Specif. 70% of the pores of the support of (I) have a dia. of 300-600A. The wt ratio of I:II is 80:20-20:80 pref. 50:50.