Abstract: A process for the polymerization of one or more conjugated dienes by means of a rare earth based catalyst in which the catalyst is formed by bringing together in liquid hydrocarbon medium in the presence of a small portion of conjugated diene: a) a rare earth salt, b) an organo aluminum and c) a silicon halide or organosilicon halide and aging the catalyst before contact with the conjugated diene(s) to be polymerized. This catalyst formation procedure offers the possibility of producing a diene polymer of high cis content with a narrower molecular weight distribution and/or smaller high molecular weight fraction which is reflected in improved processing characteristics and reduced viscosity in styrene.

Abstract: A process for preparing a catalyst for the polymerization of butadiene to obtain a polymer containing a very high content of cis isomer in which a specified neodymium carboxylate, an aluminium hydrocarbyl or aluminium hydrocarbyl hydride and a source of halogen are contacted using a particular procedure.

Abstract: A process for the removal of contaminating residues of a homogeneous catalyst comprising a hydrocarbon soluble compound of a transition metal from Group VIII of the Periodic Table and a metal alkyl or alkyl halide cocatalyst from a liquid hydrocarbon reaction product comprises treating the contaminated product with an aqueous solution of a silicate, borate or carbonate and separating and recovering the hydrocarbon phase.Residues of oligomerization catalysts, polymerization catalysts and hydrogenation catalysts are removable by this process, especially nickel, cobalt, iron, aluminium and halogen residues.