# US 4,395,388 A · Synthetic cristobalite

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,395,388 A
- Document ID: US4395388A
- Status: Granted
- Kind: A
- Application number: 06/321,531
- Filed: 1981-11-16
- Granted: 1983-07-26
- Earliest claimed: 1981-11-16
- Assignees: Standard Oil Company (Indiana)
- Inventors: James A. Kaduk
- Web page: https://patentgrep.com/patent/US4395388A

## CPC

- C01B 33/12: Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}

## Abstract

A method for preparing synthetic cristobalite comprises (1) preparing a mixture containing sources for an oxide of silicon and for an oxide of boron, a base of an alkali or alkaline earth metal or precursor of such base, a polyhydric alcohol, and water; and (2) maintaining the mixture at suitable reaction conditions to effect formulation of the cristobalite, said reaction conditions comprising a reaction temperature within the range of about 30.degree. C. to about 300.degree. C., a pressure of at least the vapor pressure of water at the reaction temperature, and a reaction time that is sufficient to effect crystallization.

## Claims

### Claim 1

A method for preparing cristobalite, which comrises: (1) preparing a mixture containing sources for an oxide of silicon and for an oxide of boron, a base or precursor of such base, a polyhydric alcohol, and water, wherein the composition of the mixture of initial reactants in terms of mole ratios of oxides is:
SiO.sub.2 /B.sub.2 O.sub.3 : 0.5-200
R(OH).sub.n /B.sub.2 O.sub.3 : 0.01-20
M.sub.2/v O/B.sub.2 O.sub.3 : 0.05-10
H.sub.2 O/SiO.sub.2 : 2-5000
wherein R is a polyvalent hydrocarbyl radical of 2 to about 5 carbon atoms, n is an interger of 2 to about 4, and M is at least one alkali or alkaline earth metal cation having a valence of v, or ammonium; and (2) maintaining the mixture at suitable reaction conditions to effect formulation of the cristobalite, said reaction conditions comprise a pH of the slurry prior to crystallization that falls within the range of about 9.0 to about 13.5, a reaction temperature within the range of about 30.degree. C. to about 300.degree. C. and a pressure of at least the vapor pressure of water at the reaction temperature.

### Claim 2 (depends on 1)

The method of claim 1, wherein the source for an oxide of boron is H.sub.3 BO.sub.3.

### Claim 3 (depends on 1)

The method of claim 1, wherein said reaction time is within the range of about 2 to about 20 days.

### Claim 4 (depends on 3)

The method of claim 3, wherein the composition of said mixture ratios of initial reactants:
SiO.sub.2 /B.sub.2 O.sub.3 : 0.7-75
R(OH).sub.n /B.sub.2 O.sub.3 : 0.01-8
M.sub.2/v /B.sub.2 O.sub.3 : 0.10-9
H.sub.2 O/SiO.sub.2 : 5-5000.

### Claim 5 (depends on 3)

The method of claim 3 wherein said polyhydric alcohol is glycerol or ethylene glycol.

### Claim 6 (depends on 3)

The method of claim 3, wherein said reaction temperature is within the range of about 50.degree. C. to about 300.degree. C., said pH is within the range of about 10.0 to about 13.0, said reaction time is within the range of about 2 days to about 12 days, and the composition of said mixture falls within the following ranges of mole ratios of initial reactants:
SiO.sub.2 /B.sub.2 O.sub.3 : 0.5-200
R(OH).sub.n /B.sub.2 O.sub.3 : 0.01-20
M.sub.2/v O/B.sub.2 O.sub.3 : 0.05-10
H.sub.2 O/SiO.sub.2 : 2-5000.

### Claim 7 (depends on 6)

The method of claim 6, wherein the composition of said mixture falls within the following ranges of mole ratios of initial reactants:
SiO.sub.2 /B.sub.2 O.sub.3 : 0.7-75
R(OH).sub.n /B.sub.2 O.sub.3 : 0.01-8
M.sub.2/v O/B.sub.2 O.sub.3 : 0.10-9
H.sub.2 O/SiO.sub.2 : 5-5000.