Crystalline silica
AssigneeUnion Carbide Corporation
InventorsRobert William Grose, Edith Marie Flanigen
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Abstract
A novel crystalline silica composition having uniform pore dimensions of approximately 6 Angstrom units is prepared by calcining a crystalline hydrated alkylonium silicate prepared hydrothermally from a reaction mixture containing as essential reagents, water, amorphous silica and a quaternary ammonium compound at a pH of at least 10. The crystalline silica, because of its uniform pore structure, is capable of making size-selective separations of molecular species, but neither it nor its silicate precursor exhibit ion-exchange properties. This absorbent has a very useful hydrophobic/organophilic characteristic which permits its use in selectively adsorbing organic materials from water, either in liquid or vapor phase.
Claims2
A silica polymorph consisting of crystalline silica, said silica polymorph after calcination in air at 600.degree. C for 1 hour, having a mean refractive index of 1.39 .+-. 0.01 and a specific gravity at 25.degree. C of 1.70 .+-. 0.05 g./cc.
A silica polymorph consisting of crystalline silica, said silica polymorph after calcination in air at 600.degree. C for 1 hour having as the six strongest d-values of its X-ray powder diffraction pattern those set forth in Table A.
Dependencies are inferred from the claim text.