CATALYSTS USEFUL IN THE PURIFICATION OF SILICON TETRAFLUORIDE

• US 20100009844A1
• Filed: 09/21/2009
• Published: 01/14/2010
• Est. Priority Date: 09/21/2007
• Status: Abandoned Application

• Current Assignee: SunEdison, Inc.
• Original Assignee: SunEdison, Inc.
• Inventors: Revankar, Vithal, Ibrahim, Jameel
• Application Number:
  US12/563,572
• Publication Number:
  US 20100009844A1
• Time in Patent Office: Days
• US Class Current: 502/241
• CPC Class Codes: B01J 21/066 Zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 23/8892 Manganese
• CPC Class Codes: B01J 23/94 of catalysts comprising metals, oxides or hydroxides of the iron group metals or copper
• CPC Class Codes: B01J 37/349 making use of flames, plasmas or lasers
• CPC Class Codes: C01B 33/10784 by adsorption
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 20/584 Recycling of catalysts

Abstract

Processes for purifying silicon tetrafluoride source gas by subjecting the source gas to one or more purification processes including: contacting the silicon tetrafluoride source gas with an ion exchange resin to remove acidic contaminants, contacting the silicon tetrafluoride source gas with a catalyst to remove carbon monoxide, by removal of carbon dioxide by use of an absorption liquid, and by removal of inert compounds by cryogenic distillation; catalysts suitable for removal of carbon monoxide from silicon tetrafluoride source gas and processes for producing such catalysts.

Claims

1. A catalyst for removing impurities from a silicon tetrafluoride gas, the catalyst comprising:

an inert substrate selected from the group consisting of zirconia, alumina silicate, silica, alumina, yttria and mixtures thereof, and

a catalytic metal oxide comprising a catalytic metal selected from the group consisting of copper, manganese, chromium, cobalt, thallium, molybdenum, silver and mixtures thereof at or near the surface of the inert substrate.

2. A catalyst as set forth in claim 1 wherein the catalytic metal oxide comprises a catalytic metal selected from the group consisting of copper, manganese and mixtures thereof.

3. A catalyst as set forth in claim 1 wherein the inert substrate comprises zirconia, alumina silicate and mixtures thereof.

4. A catalyst as set forth in claim 1 wherein the inert substrate comprises a stabilizer comprising a metal selected from the group consisting of lanthanides, actinides, magnesium, yttrium, calcium, and mixtures thereof.

5. A catalyst as set forth in claim 4 wherein the inert substrate comprises less than about 0.1% by weight stabilizer.

6. A catalyst as set forth in claim 1 wherein the inert substrate comprises less than about 0.1% by weight yttrium oxide as a stabilizer.

7. A catalyst as set forth in claim 1 wherein the catalyst comprises at least about 95% inert substrate by weight, less than about 3% catalytic metal by weight and less than about 0.5% stabilizer by weight.

8. A catalyst as set forth in claim 1 wherein the catalyst comprises from about 0.001% to about 1.0% by weight catalytic metal.

9. A catalyst as set forth in claim 1 wherein the catalyst comprises from about 95% to about 99.999% by weight inert substrate.

10. A catalyst as set forth in claim 1 wherein the substrate has a surface area from about 1 m²/g to about 1000 m²/g.

11. A catalyst as set forth in claim 1 wherein the substrate has a bulk porosity f from about 30% to about 80%.

12. A catalyst as set forth in claim 1 wherein the substrate has a micro-porosity of from about 1% to about 20%.