Patent GB-748632-A (GB)
Title: Improvements in or relating to method of polymerizing ethylene
IPC: C08F10/00
Filed: 1953-11-26
Abstract: Ethylene, with or without other monomers, is polymerized by contacting with calcium, strontium or barium carbide and using as catalyst an oxide or salt of an oxyacid of a group 6A metal, at a temperature between 100 DEG  and 350 DEG  C.  Optional monomers are propylene, isobutylene, n-butylenes, t.-butylethylene, perfluoroethylene, 3,3,3 - trifluoro - 1 - propene, perfluorobutadiene, acetylene and isoprene, and other components such as sulphur dioxide, carbon monoxide and small amounts of hydrogen (which reduces the induction period) may also be present. Catalysts specified are molybdena and the cobalt, calcium, nickel and copper salts of molybdic, chromic, tungstic and uranic acids, e.g. cobalt molybdate.  The catalyst may be supported on specified difficultly reducible metal oxides and, subsequent to the removal of the polymer (which may be continuous or intermittent), the catalyst particles may be reactivated with a reducing gas, or by extraction with water, ammonium salts or dilute acids or peracids such as permolybdic, pervanadic or pertungstic acids.  The oxide catalysts may be used in the hexavalent state or pre-reduced to a valency of 2 to 5.5.  The catalyst may be stabilized by heat, silica or alumina orthophosphate and may also be mixed with oxides of calcium, magnesium, nickel, zinc, vanadium, thorium or iron.  The polymerization may be carried out in the gaseous phase but preferably in a liquid hydrocarbon, of which many aromatic and aliphatic examples are specified, and the grease-like polymers produced may also act as media.  The liquid medium should be purified before use by treatment with acids, Friedel-Crafts catalysts, maleic anhydride, calcium, alkali metals, metallic hydrides, hydrogen or hydrogenation catalysts or by filtration through copper grains.  The monomer feed may be dehydrated with calcium sulphate or the metal carbide and may be decarbonated with sodium hydroxide/asbestos.  The process may be carried out continuously or stepwise by repressurizing with ethylene, and gives products of high molecular weight which may be mixed with antioxidants, stabilizers, fillers, extenders, plasticizers, pigments, insecticides, fungicides, lower molecular weight polyethylene, hydrocarbon oils, lubricating oils, xylene, paraffin, petrolatum and ester waxes and higher molecular weight polybutylenes. The polymers may be halogenated, halogenated and subsequently dehalogenated, sulphohalogenated, e.g. with sulphuryl chloride, or sulphonated and may be converted into sponges or latices.ALSO:Ethylene, with or without other monomers, is polymerized (see Group IV(a)) by contacting with calcium, strontium or barium carbide and a catalyst comprising an oxide or salt of an oxyacid of a group 6A metal, at a temperature between 100 DEG  and 350 DEG C.  The catalyst may be used in the form of powder, granules, microspheres, broken filter cake, lumps or pellets and specified are molybdena and the cobalt, calcium, nickel and copper salts of molybdic, chromic, tungstic and uranic acids, e.g. cobalt molybdate.  The catalyst may be supported on alumina, titania, zirconia, silica gel, kieselguhr, diatomite, silica/alumina, aluminosilicates or carbon and, subsequent to the removal of the polymer, may be reactivated with a reducing gas such as hydrogen and/or carbon monoxide, sulphur dioxide, hydrogen sulphide or dehydrogenatable hydrocarbons, or by extraction with water, ammonium salts, dilute acids or peracids such as permolybdic, pervanadic and pertungstic.  The oxide catalysts may be used in the hexavalent state or may be pre-reduced with a reducing gas or with lithium aluminium hydride, e.g. to a valency of from 2 to 5.5.  The catalyst may if desired be stabilized by heat, silica or alumina orthophosphate and may also be mixed with oxides of calcium, magnesium, nickel, zinc, vanadium, thorium or iron.