| 摘要 |
Olefines are polymerized using a catalyst comprising chromium oxide, containing from 0.01 to 50 weight per cent of chromium, imprenated on finely divided porous silica gel having a pore diameter of 200 to 500 </>rA and a surface area of 250 to 350 square metres per gram, said catalyst having been activated by heating at a temperature of at least 1200 DEG F. and up to 1800 DEG F. Preferably at least a portion of the chromium oxide is in the hexavalent state. Suitable olefines are C2 to C8 olefines, diolefines such as butadiene and isoprene, conjugated diolefines and copolymers of the above such as ethylene-butylene and ethylene-propylene copolymers. In the example ethylene is polymerized in the presence of n-pentane using a chromium oxide-silica gel catalyst as above. Specification 790,195 is referred to. |
