# US 2021/0276876 A1 · Synthesis of high purity beta-silicon carbide

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- Number: US 2021/0276876 A1
- Document ID: US20210276876A1
- Status: Published application
- Kind: A1
- Application number: 17/193,900
- Filed: 2021-03-05
- Published: 2021-09-09
- Earliest claimed: 2020-03-05
- Assignees: University of Wyoming
- Applicants: University of Wyoming
- Inventors: Maohong Fan; Kaidi Sun; Tongtong Wang; Zhe Chen; Wenyang Lu; Xin He; Weibo Gong; Richard Arthur Horner
- Web page: https://patentgrep.com/patent/US20210276876A1

## CPC

- C01B 32/97: Preparation from SiO or SiO2
- Y02P 20/54: using solvents, e.g. supercritical solvents or ionic liquids
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A clean and low-cost approach for reusing waste residual from coal utilization and sandstone powder is disclosed. The coal waste residual may be produced from any thermal, solvent extraction or combination process. For example, a sustainable and environmentally friendly method for synthesis of beta-silicon carbide (β-SiC) using, for example, the residual of Powder River Basin (PRB) coal extraction derived from ethanol and supercritical CO2 (EtOH-SCC) extraction combined with natural sandstone.

## Claims

### Claim 1

A method for synthesis of beta-silicon, comprising:
providing a residual derived from coal and a sandstone powder derived from sandstone;
removing impurities from the residual and the sandstone powder;
mixing the purified residual and sandstone powder;
carbonizing the mixture of residual and sandstone powder for synthesis of beta-silicon; and
treating the beta-silicon to remove any unreacted carbon.

### Claim 2 (depends on 1)

The method of claim 1, wherein the residual comprises a solvent extracted residue.

### Claim 3 (depends on 1)

The method of claim 1, wherein the residual comprises an extract derived from PRB coal.

### Claim 4 (depends on 1)

The method of claim 1, wherein the residual comprises EtOH-SCC.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
treating the residual with ethanol to remove liquid tar.

### Claim 6 (depends on 14)

The method of claim 14, further comprising:
drying the residual under vacuum to remove the ethanol.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
cleaning the residual and the sandstone powder before mixing.

### Claim 8 (depends on 1)

The method of claim 1, further comprising:
removing impurities from the residual and the sandstone powder with an acid.

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
heating the residual, the sandstone powder and the mixture of residual and sandstone powder in separate steps.

### Claim 10 (depends on 1)

The method of claim 1, wherein carbonizing at 1300-1600° C. with holding times of 1-3 hours under an Argon gas flow.

### Claim 11 (depends on 1)

The method of claim 1, further comprising:
crushing the residual into particles less than 250 μm.

### Claim 12

A method for synthesis of beta-silicon, comprising:
providing an extract derived from PRB coal and a sandstone powder derived from sandstone;
removing impurities from the extract and the sandstone powder with an acid;
mixing the purified extract and sandstone powder;
carbonizing the mixture of extract and sandstone powder for synthesis of beta-silicon under an inert gas flow; and
treating the beta-silicon with an organic chemical compound to remove any unreacted carbon.

### Claim 13 (depends on 12)

The method of claim 12, wherein the extract comprises EtOH-SCC.

### Claim 14

A method for synthesis of beta-silicon from carbon fiber production residual and a sandstone comprising:
providing a residual taken from carbon fiber production using coal and a sandstone powder;
treating the residual for extracting liquid tar;
removing impurities from the residual and the sandstone powder;
mixing the clean residual and sandstone powder;
carbonizing the mixture of residual and sandstone powder for synthesis of beta-silicon; and
treating the beta-silicon to remove any unreacted carbon.

### Claim 15 (depends on 14)

The method of claim 14, wherein the residual is treated with ethanol to remove liquid tar.

### Claim 16 (depends on 14)

The method of claim 14, further comprising:
removing impurities from the residual and the sandstone powder with HCl.

### Claim 17 (depends on 14)

The method of claim 14, further comprising:
crushing the residual into particles less than 250 sm.

### Claim 18 (depends on 14)

The method of claim 14, further comprising:
heating the residual, the sandstone powder and the mixture of residual and sandstone powder in separate steps.

### Claim 19 (depends on 14)

The method of claim 14, wherein carbonizing at 1300-1600° C. with holding times of 1-3 hours under an Argon gas flow.

### Claim 20 (depends on 14)

The method of claim 14, wherein the residual comprises at least one of EtOH-SCC, solvent extracted residue, or extract derived from PRB coal.