Metal oxide stabilized chromatography packings

Claim 2

Surface-stabilized, porous silica bodies having uniform pore size and a particle diameter range of about 0.5-100 microns and having partial surface coverage of metal oxide in quantities insufficient to form a continuous layer over the silica but sufficient to effect an improvement in hydrolytic stability as compared to uncoated silica, thereby providing a surface mosaic of metal oxide and silicon oxide.

Claim 3

The surface-stabilized silica bodies of claim 1 wherein the surface coverage is in the range of approximately 0.25 to less than 4 μmole metal compound per square meter of silica surface area.

Claim 4

The surface-stabilized silica bodies of claim 1 wherein the starting material is uniform-sized silica microspheres.

Claim 5

The surface-stabilized silica bodies of claim 3 wherein the microspheres are prepared by a process comprising the steps of: (A) forming a sol of uniform-sized colloidal silica particles in a polar liquid, wherein the colloidal particles have hydroxylated surfaces and are dispersible in said polar liquid; (B) forming a mixture of the sol with a polymerizable organic material which is initially sufficiently miscible in said polar liquid to form a uniform mixture; (C) initiating polymerization of the organic material in said mixture to cause coacervation of the organic material and said colloidal particles into substantially spherical microspheres having a diameter of about 0.5-20.0 microns; (D) solidifying the microspheres so formed; (E) collecting, washing and drying said microspheres; and (F) oxidizing said microspheres to elevated temperatures to burn off the organic material without melting said colloidal particles.

Claim 6

The surface-stabilized silica bodies of claim 4 wherein the colloidal silica particles have a size range of 5-500 millimicrons and wherein the polymerizable organic material is urea/formaldehyde or melamine/formaldehyde.

Claim 7

A chromatographic packing comprising surface-stabilized, porous silica bodies having uniform pore size and a particle diameter range of about 0.5-100 microns, having partial surface coverage of metal oxide in quantities insufficient to form a continuous surface layer over the silica but sufficient to effect an improvement in hydrolytic stability as compared to uncoated silica and having a covalently attached organosilane coating.

Claim 8

A chromatographic packing comprising surface-stabilized, porous silica bodies having uniform pore size and a particle diameter range of about 0.5-100 microns, having partial surface coverage of metal oxide in quantities insufficient to form a continuous surface layer over the silica but sufficient to effect an improvement in hydrolytic stability as compared to uncoated silica and having a covalently attached organosilane coating.

Claim 9

The chromatographic packing of claim 6 wherein the surface coverage is in the range of approximately 0.25 to less than 4 μmole metal compound per square meter of silica surface area.

Claim 10

The chromatographic packing of claim 6 wherein the silica bodies are microspheres prepared by a process comprising the steps of: (A) forming a sol of uniform-sized colloidal silica particles in a polar liquid, wherein the colloidal particles have hydroxylated surfaces and are dispersible in said polar liquid; (B) forming a mixture of the sol with a polymerizable organic material which is initially sufficiently miscible in said polar liquid to form a uniform mixture; (C) initiating polymerization of the organic material in said mixture to cause coacervation of the organic material and said colloidal particles into substantially spherical microspheres having a diameter of about 0.5-20.0 microns; (D) solidifying the microspheres so formed; (E) collecting, washing and drying said microspheres; and (F) oxidizing said microspheres to elevated temperatures to burn off the organic material without melting said colloidal particles.

Claim 11

The chromatographic packing of claim 6 wherein the metal oxide is zirconium oxide.

Claim 12

A process for preparing surface-stabilized, porous silica bodies comprising the steps of: (A) mixing an aqueous suspension of porous silica bodies with an aqueous solution of a metal compound both in amounts sufficient to provide a final average coverage in the range of approximately 0.25 to less than 4 μmol metal compound per square meter of silica surface area; (B) removing trapped air from the silica body pore structure, for example, by boiling the suspension at reduced pressure; (C) separating the solids from the solution; (D) drying the solids to remove surface moisture; and (E) heating to temperatures in the range of 600°-1000° C. for from 10 to 72 hours.

Claim 13

A process for preparing surface-stabilized, porous silica bodies comprising the steps of: (A) mixing an aqueous suspension of porous silica bodies with an aqueous solution of a metal compound both in amounts sufficient to provide a final average coverage in the range of approximately 0.25 to less than 4 μmol metal compound per square meter of silica surface area; (B) removing trapped air from the silica body pore structure, for example, by boiling the suspension at reduced pressure; (C) separating the solids from the solution; (D) drying the solids to remove surface moisture; and (E) heating to temperatures in the range of 600°-1000° C. for from 10 to 72 hours.

Claim 14

The process of claim 10 wherein the porous silica bodies are microspheres prepared by a process comprising the steps of: (A) forming a sol of uniform-sized colloidal silica particles in a polar liquid, wherein the colloidal particles have hydroxylated surfaces and are dispersible in said polar liquid; (B) forming a mixture of the sol with a polymerizable organic material which is initially sufficiently miscible in said polar liquid to form a uniform mixture; (C) initiating polymerization of the organic material in said mixture to cause coacervation of the organic material and said colloidal particles into substantially spherical microspheres having a diameter of about 0.5-20.0 microns; (D) solidifying the microspheres so formed; (E) collecting, washing and drying said microspheres; and (F) oxidizing said microspheres to elevated temperatures to burn off the organic material without melting said colloidal particles.

Claim 15

The process of claim 10 wherein the metal compound is a salt of at least one of the following: Zr, Co, Fe, Al, Ti, Mo, Hf, Ni, Zn and Th.

Claim 16

The process of claim 12 wherein the metal salt is selected from the group consisting of ZrBr 4 , ZrCl 4 , ZrOSO 4 , ZrO(NO 3 ) 3 , ZrOCO 2 and ZrOCl 2 .

Claim 17

Surface-stabilized, porous silica bodies having uniform pore size and a particle diameter range of about 0.5-100 microns and having partial surface coverage of zirconium oxide in the amount of approximately 1 μmole of oxide per square meter of silica surface area.

Claim 18

Surface-stabilized, porous silica bodies having uniform pore size and a particle diameter range of about 0.5-100 microns and having partial surface coverage of zirconium oxide in the amount of approximately 1 μmole of oxide per square meter of silica surface area.

Claim 19

A chromatographic packing comprising surface-stabilized, porous silica bodies having uniform pore size and a particle diameter range of about 0.5-100 microns and having partial surface coverage of zirconium oxide in the amount of approximately 1 μmole of oxide per square meter of silica surface area and having a covalently attached organosilane coating.

Claim 20

A chromatographic packing comprising surface-stabilized, porous silica bodies having uniform pore size and a particle diameter range of about 0.5-100 microns and having partial surface coverage of zirconium oxide in the amount of approximately 1 μmole of oxide per square meter of silica surface area and having a covalently attached organosilane coating.