Methods for making a supported chromium catalyst are disclosed, and can comprise contacting a silica-coated alumina containing at least 30 wt. % silica with a chromium-containing compound in a liquid, drying, and calcining in an oxidizing atmosphere at a peak temperature of at least 650° C. to form the supported chromium catalyst. The supported chromium catalyst can contain from 0.01 to 20 wt. % chromium, and typically can have a pore volume from 0.5 to 2 mL/g and a BET surface area from 275 to 550 m.sup.2/g. The supported chromium catalyst subsequently can be used to polymerize olefins to produce, for example, ethylene-based homopolymers and copolymers having high molecular weights and broad molecular weight distributions.

Supported chromium catalysts with an average valence less than +6 and having a hydrocarbon-containing or halogenated hydrocarbon-containing ligand attached to at least one bonding site on the chromium are disclosed, as well as ethylene-based polymers with terminal alkane, aromatic, or halogenated hydrocarbon chain ends. Another ethylene polymer characterized by at least 2 wt. % of the polymer having a molecular weight greater than 1,000,000 g/mol and at least 1.5 wt. % of the polymer having a molecular weight less than 1000 g/mol is provided, as well as an ethylene homopolymer with at least 3.5 methyl short chain branches and less than 0.6 butyl short chain branches per 1000 total carbon atoms.

Macrocyclic polyalkene homopolymers and copolymers can be formed and converted to macrocyclic polyalkanes or macrocyclic poly(alkane-co-alkene) upon hydrogenation or, when the macrocyclic polyalkene is reacted with an alkene in the presence of an olefin metathesis catalyst, to a macrocyclic poly(alkane-co-alkene) comprising vicinal —C(═CR2)—'s. Upon hydrogenation of a macrocyclic poly(alkane-co-alkene) comprising vicinal —C(═CR2)-'s, macrocyclic poly(alkane)s or poly(alkane-co-alkene)s with isolated —C(═CR2)- groups can be provided, depending on the degree of hydrogenation. The poly(alkane-co-alkene)s with isolated —C(═CR2)- units can be used to form poly(macrocyclic poly(alkane-co-alkene))s, poly(macrocyclic poly(alkane))s, and/or bi-, tri-, and/or multi-macrocyclic poly(alkane-co-alkene)s or bi-, tri-, and/or multi-macrocyclic poly(alkane)s.

A composition, such as a catalyst precursor or a catalyst comprising a Cr coated silica support with particularly defined levels of Na and Al, such that the resulting Cr/Silica catalyst has an increased MI potential is disclosed. In an embodiment, the disclosed catalyst composition comprises a silica-containing substrate made using a base-set gel and comprising a catalytically active metal consisting of Cr, with Al impurities of less than 50 ppm and Na in an amount of less than 800 ppm of the catalyst composition. The disclosed composition has an increased MI potential over a catalyst having higher Al content, a lower Na:Al ratio, or both. Methods of making the disclosed composition, and methods of using it to prepare a polyethylene are also disclosed.

A composition, such as a catalyst precursor or a catalyst comprising a Cr coated silica support with particularly defined levels of Na and Al, such that the resulting Cr/Silica catalyst has an increased MI potential is disclosed. In an embodiment, the disclosed catalyst composition comprises a silica-containing substrate made using a base-set gel and comprising a catalytically active metal consisting of Cr, with Al impurities of less than 50 ppm and Na in an amount of less than 800 ppm of the catalyst composition. The disclosed composition has an increased MI potential over a catalyst having higher Al content, a lower Na:Al ratio, or both. Methods of making the disclosed composition, and methods of using it to prepare a polyethylene are also disclosed.

A method comprising a) drying a support material comprising silica at temperature in the range of from about 150° C. to about 220° C. to form a dried support; b) contacting the dried support with methanol to form a slurried support; c) subsequent to b), cooling the slurried support to a temperature of less than about 60° C. to form a cooled slurried support; d) subsequent to c), contacting the cooled slurried support with a titanium alkoxide to form a titanated support; and e) thermally treating the titanated support by heating to a temperature of equal to or greater than about 150° C. for a time period of from about 5 hours to about 30 hours to remove the methanol and yield a dried titanated support.

A method comprising a) drying a support material comprising silica at temperature in the range of from about 150° C. to about 220° C. to form a dried support; b) contacting the dried support with methanol to form a slurried support; c) subsequent to b), cooling the slurried support to a temperature of less than about 60° C. to form a cooled slurried support; d) subsequent to c), contacting the cooled slurried support with a titanium alkoxide to form a titanated support; and e) thermally treating the titanated support by heating to a temperature of equal to or greater than about 150° C. for a time period of from about 5 hours to about 30 hours to remove the methanol and yield a dried titanated support.

A hydrogel comprising water, and a plurality of titanium-silica nanoparticle agglomerates, wherein each titanium-silica nanoparticle agglomerate is an agglomeration of titanium-silica nanoparticles, the agglomerates having an average titanium loading designated x with a coefficient of variation for the average titanium loading of less than about 1.0, wherein a silica content of the hydrogel is of from about 10 wt. % to about 35 wt. % based on a total weight of the hydrogel.

A hydrogel comprising water, and a plurality of titanium-silica nanoparticle agglomerates, wherein each titanium-silica nanoparticle agglomerate is an agglomeration of titanium-silica nanoparticles, the agglomerates having an average titanium loading designated x with a coefficient of variation for the average titanium loading of less than about 1.0, wherein a silica content of the hydrogel is of from about 10 wt. % to about 35 wt. % based on a total weight of the hydrogel.

A method comprising a) drying a support material comprising silica at temperature in the range of from about 150° C. to about 220° C. to form a dried support; b) contacting the dried support with methanol to form a slurried support; c) subsequent to b), cooling the slurried support to a temperature of less than about 60° C. to form a cooled slurried support; d) subsequent to c), contacting the cooled slurried support with a titanium alkoxide to form a titanated support; and e) thermally treating the titanated support by heating to a temperature of equal to or greater than about 150° C. for a time period of from about 5 hours to about 30 hours to remove the methanol and yield a dried titanated support.