Induction-coupled plasma synthesis of boron nitride nanotubes

• US 10,035,705 B2
• Filed: 08/29/2017
• Issued: 07/31/2018
• Est. Priority Date: 11/01/2013
• Status: Active Grant

• Current Assignee: BNNT, LLC
• Original Assignee: BNNT, LLC
• Inventors: Smith, Michael W., Jordan, Kevin C., Stevens, Jonathan C.
• Primary Examiner(s): Gregorio, Guinever S
• Application Number:
  US15/689,500
• Publication Number:
  US 20180029885A1
• Time in Patent Office: 336 Days
• Field of Search: None
• CPC Class Codes: B01J 10/005 carried out at high temperatures in the presence of a molten material
• CPC Class Codes: B01J 19/08 Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor application of shock waves B01J3/08
• CPC Class Codes: B01J 19/088 giving rise to electric discharges for heating purposes H05B7/00; for the production of ozone C01B13/11, H01T19/00
• CPC Class Codes: B01J 2219/0898 Hot plasma
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 21/064 with boron
• CPC Class Codes: C01B 21/0641 Preparation by direct nitridation of elemental boron
• CPC Class Codes: C01P 2004/13 Nanotubes
• CPC Class Codes: C01P 2004/133 Multiwall nanotubes

Abstract

Described herein are processes and apparatus for the large-scale synthesis of boron nitride nanotubes (BNNTs) by induction-coupled plasma (ICP). A boron-containing feedstock may be heated by ICP in the presence of nitrogen gas at an elevated pressure, to form vaporized boron. The vaporized boron may be cooled to form boron droplets, such as nanodroplets. Cooling may take place using a condenser, for example. BNNTs may then form downstream and can be harvested.

Claims

1. A process for synthesizing boron nitride nanotubes (BNNTs), the process comprising:

a. introducing a feed consisting of gas including nitrogen and a boron-containing feedstock into a chamber;

b. heating the nitrogen gas and boron-containing feedstock with an induction-coupled plasma to form heated reactants;

c. triggering formation of BNNTs downstream of the induction-coupled plasma; and

d. collecting the BNNTs.

2. The process of claim 1, wherein the formation of BNNTs is triggered by at least one of introducing asperities into the chamber, natural nucleation, and cooling with a condenser.

3. The process of claim 1, wherein the formation of BNNTs is triggered by at least one of a copper rod, a tungsten wire, a network of copper rods, a network of tungsten wires, a grid of copper rods, and a grid of tungsten wires.

4. The process of claim 1, wherein the process proceeds with no reactive feedstock other than boron and nitrogen.

5. The process of claim 1, wherein the collecting is performed using at least one of a solid surface condenser, collection surfaces, and filters downstream of the growth zone.

6. The process of claim 1, wherein introducing nitrogen gas and a boron-containing feedstock into a chamber is a continuous process.

7. The process of claim 1, wherein collecting BNNTs is a continuous process.

8. The process of claim 1, wherein the chamber is at an elevated pressure of at least 2 atmospheres to about 250 atmospheres.

9. The process of claim 8, wherein the chamber is at an elevated pressure of at least 2 atmospheres to about 12 atmospheres.

10. The process of claim 1, wherein the heated reactants comprise boron nanodroplets.

11. The process of claim 1, wherein the boron-containing feedstock comprises at least one of elemental boron, elemental boron powder, boron nitride, boron nitride powder, cubic boron nitride powder, and hexagonal boron nitride powder.

12. The process of claim 1, wherein the feed is introduced at a feed inlet, and the heated reactants are formed downstream of the feed inlet.

13. The process of claim 1, wherein collecting BNNTs is a continuous process.

14. The process of claim 1, wherein the chamber is at an elevated pressure of at least 2 atmospheres to about 250 atmospheres.

15. The process of claim 1, wherein the feed is introduced at a feed inlet, and the heated reactants are formed downstream of the feed inlet.

16. A process for synthesizing boron nitride nanotubes (BNNTs), the process comprising:

a. continuously introducing reactants consisting of nitrogen and a boron-containing feedstock into a chamber to form a reactant feed;

b. passing the reactant feed through an induction-coupled plasma to heat the reactant feed at least the vaporization temperature of the boron-containing feedstock to form a heated reactant feed;

c. triggering formation of BNNTs from the heated reactant;

feed downstream of the induction-coupled plasma; and

d. collecting the BNNTs.

17. The process of claim 16, wherein triggering the formation of BNNTs is by at least one of introducing asperities into the chamber, natural nucleation, and cooling with a condenser.

18. The process of claim 16, wherein the formation of BNNTs is triggered by at least one of a copper rod, a tungsten wire, a network of copper rods, a network of tungsten wires, a grid of copper rods, and a grid of tungsten wires.

19. The process of claim 16, wherein the process proceeds with no reactive feedstock other than boron and nitrogen.

20. The process of claim 16, wherein the collecting is performed using at least one of a solid surface condenser, collection surfaces, and filters downstream of the growth zone.