Chemical dehydroxylation of silica
AssigneePhillips Petroleum Company
InventorMax P. McDaniel
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Abstract
Silica having an enhanced level of dehydration beyond what can be produced by heating alone is produced by a three step process comprising (1) chlorination, (2) dechlorination, and (c) oxidation. The resulting dehydroxylated silica is a novel composition of matter and is useful as a reinforcing agent in rubber or plastics and as a support for a chromatographic column in addition to being suitable for a catalyst support. Where the dechlorinating agent is hydrogen, a hydrophobic silica composition containing.tbd.Si-H structures and essentially no -OH groups is produced which is suitable for use as a reducing agent, a coupling agent as well as a precursor for the oxidized dehydroxylated silica described above. The resulting composition is particularly suitable as a support for chromium-containing olefin polymerization catalysts.
Claims13
A polymerization process comprising contacting at least one mono-1-olefin having 2 to 8 carbon atoms per molecule with a catalyst produced by (1) subjecting a silica-containing composition at an elevated temperature to a chlorinating agent, (2) subjecting the resulting chlorinated silica-containing composition to a dechlorination treatment at an elevated temperature to remove chlorine, and (3) oxidizing the thus dechlorinated composition at a temperature between 600.degree. C. and the sintering temperature for said silica-containing composition, incorporating a chromium compound into said dechlorinated silica-containing composition under anhydrous conditions and thereafter activating the resulting catalyst at a temperature within the range of 15.degree. C. to 870.degree. C. for a time of at least 5 minutes.
Dependencies are inferred from the claim text.