Abstract: A polymerization catalyst is prepared by a process which includes the step of treating silica-supported chromium oxide with a permanganate compound such as potassium permanganate. The catalyst is then activated such as by sequential heating in a reducing atmosphere and an oxidizing atmosphere. The catalyst can be used in particle-form polymerization to produce ethylene polymers having lowered shear response for a given melt index.

Abstract: A chromium salt such as ammonium chromate or ammonium dichromate, which is normally insoluble in nonaqueous solvents which do not easily rehydrate the silica surface is solubilized, for instance by treating it with a crown ether, and impregnated onto a particulate support from a nonaqueous solvent which does not easily rehydrate the silica. The resulting composition is then activated in an oxygen ambient such as air in a conventional manner and then utilized as a catalyst for polymerization reactions such as the production of polyolefins.

Abstract: In accordance with a first embodiment of this invention, a silica xerogel is aqueously impregnated with a titanium compound which is resistant to hydrolysis. In accordance with a second embodiment of this invention, a silica hydrogel containing a titanium compound resistant to hydrolysis is dried. In this embodiment, the hydrogel preferably also contains a pore preserving agent. This invention makes possible the use of aqueous impregnation of titanium and conventional drying techniques to give a catalyst having characteristics associated with azeotrope dried silica-titanium coprecipitated catalyst. The catalysts of this invention are useful in olefin polymerization processes, particularly in the polymerization of predominantly ethylene monomer systems under slurry conditions.

Abstract: A chromium salt such as ammonium chromate or ammonium dichromate, which is normally insoluble in nonaqueous solvents which do not easily rehydrate the silica surface is solubilized, for instance by treating it with a crown ether, and impregnated onto a particulate support from a nonaqueous solvent which does not easily rehydrate the silica. The resulting composition is then activated in an oxygen ambient such as air in a conventional manner and then utilized as a catalyst for polymerization reactions such as the production of polyolefins.

Abstract: A process comprising treating silica with at least one of selenium or tellurium under nonoxidizing conditions at a temperature of at least 370.degree. C. and a subsequent second step wherein the thus-treated silica is contacted with an oxidizing ambient at a temperature within the range of 370.degree.-900.degree. C. The silica can contain a chromium compound in which case the resulting product is suitable as a catalyst for the production of higher melt flow olefin polymers suitable for such applications as injection molding, and the like requiring a relatively narrow molecular weight distribution.

Abstract: In accordance with a first embodiment of this invention, a silica xerogel is aqueously impregnated with a titanium compound which is resistant to hydrolysis. In accordance with a second embodiment of this invention, a silica hydrogel containing a titanium compound resistant to hydrolysis is dried. In this embodiment, the hydrogel preferably also contains a pore preserving agent. This invention makes possible the use of aqueous impregnation of titanium and conventional drying techniques to give a catalyst having characteristics associated with azeotrope dried silica-titanium coprecipitated catalyst. The catalysts of this invention are useful in olefin polymerization processes, particularly in the polymerization of predominantly ethylene monomer systems under slurry conditions.

Abstract: A process comprising treating silica with at least one of selenium or tellurium under nonoxidizing conditions at a temperature of at least 370.degree. C. and a subsequent second step wherein the thus-treated silica is contacted with an oxidizing ambient at a temperature within the range of 370.degree.-900.degree. C. The silica can contain a chromium compound in which case the resulting product is suitable as a catalyst for the production of higher melt flow olefin polymers suitable for such applications as injection molding, and the like requiring a relatively narrow molecular weight distribution.

Abstract: A method for improving the thermal stability of polymer of ethylene having vinyl unsaturation in which the polymer is admixed with a stabilizing amount of a silane compound represented by the formulae R.sub.2 SiA.sub.2 and R.sub.3 SiA' in which each R is the same or different and is selected from aryl, alkaryl, or aralkyl groups containing from 6 to about 24 carbon atoms, each A is the same or different and is selected from hydrogen, azido, halogen, hydroxy, alkoxy groups in which the alkyl radical contains from 1 to about 10 carbon atoms, and alkenyl of 2 to 6 carbon atoms and one A can be lower alkyl of 1 to 6 carbon atoms with the other A selected from among azido, halogen, hydroxy, and alkoxy, lower alkyl and alkenyl as described above, and A' is selected from among halogen, hydrogen and hydroxy groups. The composition of matter produced thereby. A composition of matter containing a polymer of ethylene and a thermally stabilizing amount of a silane represented by the formulae R.sub.2 SiA.sub.2 and R.sub.