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.

Disclosed are saturated cyclic monopolymers derived from hexyne, octyne, nonyne, pentadecyne and saturated cyclic copolymers derived from acetylene and a second alkyne monomer that is hexyne, octyne, nonyne, or pentadecyne.

Disclosed are saturated cyclic monopolymers derived from hexyne, octyne, nonyne, pentadecyne and saturated cyclic copolymers derived from acetylene and a second alkyne monomer that is hexyne, octyne, nonyne, or pentadecyne.

A method comprising contacting a silica support with a titanium-containing solution to form a titanated silica support, wherein the titanium-containing solution comprises a solvent; a ligand comprising a glycol, a carboxylate, a peroxide, or a combination thereof, and a titanium compound having the formula Ti(acac).sub.2(OR).sub.2, wherein “acac” is acetylacetonate and wherein each R independently is ethyl, isopropyl, n-propyl, isobutyl, or n-butyl.

A method comprising contacting a silica support with a titanium-containing solution to form a titanated silica support, wherein the titanium-containing solution comprises a solvent; a ligand comprising a glycol, a carboxylate, a peroxide, or a combination thereof, and a titanium compound having the formula Ti(acac).sub.2(OR).sub.2, wherein “acac” is acetylacetonate and wherein each R independently is ethyl, isopropyl, n-propyl, isobutyl, or n-butyl.

Disclosed are saturated cyclic monopolymers derived from hexyne, octyne, nonyne, pentadecyne and saturated cyclic copolymers derived from acetylene and a second alkyne monomer that is hexyne, octyne, nonyne, or pentadecyne.

Disclosed are saturated cyclic monopolymers derived from hexyne, octyne, nonyne, pentadecyne and saturated cyclic copolymers derived from acetylene and a second alkyne monomer that is hexyne, octyne, nonyne, or pentadecyne.

This disclosure provides for polymerization processes of polyolefins wherein the melt index can be regulated. For example, there is provided a process for producing a polyethylene, the process comprising: (1) in a polymerization reactor, contacting (a) a polymerization catalyst, (b) ethylene, (c) an optional α-olefin comonomer, and (d) (x+y) ppm by weight of an antistatic agent on an ethylene basis; and (2) applying reaction conditions to the reaction mixture suitable to produce the polyethylene having a desired set of characteristics, such as desired target melt index. The disclosed polymerization processes allow for production of polyolefins having higher melt indices, and in the alternative to produce polyolefins having a desired target melt index at lower polymerization temperatures.

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.