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.
Claims23
A method comprising (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.
A method of producing a hydrophobic silica having Si--H units and essentially no OH comprising (1) subjecting silica to a chlorinating agent selected from CCl.sub.4, COCl.sub.2, Cl.sub.2, C.sub.2 Cl.sub.4, SO.sub.2 Cl.sub.2 and SOCl.sub.2 at a temperature within the range of 350.degree. to about 900.degree. C. and thereafter subjecting the resulting chlorinated silica to treatment with a hydrogen-containing ambient at a temperature within the range of 250.degree. to 900.degree. C.
A composition consisting essentially of a silica-containing material selected from particulate catalytic grade silica, silica alumina, silica-boria, silica-titania, silica-zirconia, or mixtures thereof containing 0.0-OH groups per square millimicron wherein silica constitutes from 80 to 100 weight percent of said silica-containing material.
Dependencies are inferred from the claim text.