Abstract: A catalyst system useful for the polymerization of ethylene and other .alpha.-olefins comprising (a) a silica-supported chromium oxide catalyst and (b) a dihydrocarbylboron monohydrocarbyloxide adjuvant. The catalyst system results in .alpha.-olefin polymers having a broadened molecular weight distribution in the high molecular portion.

Abstract: Method and apparatus for fractionating a hot vaporous hydrocarbon feed from a fluid catalytic cracking reactor wherein the hot vaporous feed is introduced into a fractionator zone near one end thereof and liquid is removed from a liquid collection zone and cooled in a heat extraction zone. A first portion of the cooled liquid is returned to a location between the liquid collection zone and the point of introduction of the vaporous feed and sprayed directly on hot condensed liquid flowing downwardly over an inclined baffle plate to quickly quench the liquid below the temperature at which polymerization of the constituents of the liquid can occur.