REACTOR AND METHOD FOR PRODUCTION OF NANOSTRUCTURES

• US 20120027955A1
• Filed: 10/09/2008
• Published: 02/02/2012
• Est. Priority Date: 10/09/2007
• Status: Abandoned Application

• Current Assignee: University of Louisville
• Original Assignee: University of Louisville
• Inventors: Sunkara, Mahendra Kumar, Kim, Jeong H., Kumar, Vivekanand
• Application Number:
  US12/248,731
• Publication Number:
  US 20120027955A1
• Time in Patent Office: Days
• US Class Current: 427/575
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 1/02 Oxides
• CPC Class Codes: C01G 19/02 Oxides
• CPC Class Codes: C01G 23/047 Titanium dioxide
• CPC Class Codes: C01G 23/07 Producing by vapour phase processes, e.g. halide oxidation
• CPC Class Codes: C01G 9/00 Compounds of zinc
• CPC Class Codes: C01G 9/02 Oxides; Hydroxides
• CPC Class Codes: C01G 9/03 Processes of production using dry methods, e.g. vapour phase processes
• CPC Class Codes: C01P 2002/82 by IR- or Raman-data
• CPC Class Codes: C01P 2004/16 Nanowires or nanorods, i.e. solid nanofibres with two nearly equal dimensions between 1-100 nanometer
• CPC Class Codes: C01P 2004/17 Nanostrips, nanoribbons or nanobelts, i.e. solid nanofibres with two significantly differing dimensions between 1-100 nanometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01J 37/32834 Exhausting
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence
• CPC Class Codes: H05H 2245/50 Production of nanostructures

Abstract

A reactor and method for production of nanostructures produces, for example, metal oxide nanowires or nanoparticles. The reactor includes a metal powder delivery system wherein the metal powder delivery system includes a funnel in communication with a dielectric tube; a plasma-forming gas inlet, whereby a plasma-forming gas is delivered substantially longitudinally into the dielectric tube; a sheath gas inlet, whereby a sheath gas is delivered into the dielectric tube; and a microwave energy generator coupled to the dielectric tube, whereby microwave energy is delivered into a plasma-forming gas. The method for producing nanostructures includes delivering a plasma-forming gas substantially longitudinally into a dielectric tube; delivering a sheath gas into the tube; forming a plasma from the plasma-forming gas by applying microwave energy to the plasma-forming gas; delivering a metal powder into the dielectric tube; and reacting the metal powder within the plasma to form metal oxide nanostructures.

Claims

1. A reactor for producing metal oxide nanostructures, comprising:

a) a metal powder delivery system in communication with a dielectric tube;

b) a plasma-forming gas inlet in communication with the dielectric tube, whereby a plasma-forming gas is delivered substantially longitudinally into the dielectric tube;

c) a sheath gas inlet in communication with the dielectric tube, whereby a sheath gas is delivered into the dielectric tube; and

d) a microwave energy generator coupled to the dielectric tube, whereby microwave energy is delivered into the dielectric tube and to the plasma-forming gas.

2. The reactor of claim 1, wherein the metal powder delivery system comprises a funnel.

3. The reactor of claim 2, wherein the metal powder delivery system is a conical funnel.

4. The reactor of claim 1, wherein the metal powder delivery system is cooled.

5. The reactor of claim 3, wherein the metal powder delivery system is liquid cooled.

6. The reactor of claim 1, wherein the sheath gas inlet is angled with respect to a longitudinal axis of the dielectric tube.

7. The reactor of claim 6, wherein the sheath gas inlet is angled at about 40°

to about 50°

with respect to the longitudinal axis of the dielectric tube.

8. The reactor of claim 1, further including a recycle system in communication with the dielectric tube.

9. The reactor of claim 8, wherein the recycle system is also in communication with the plasma-forming gas inlet.

10. The reactor of claim 8, wherein the recycle system includes a nanostructure separator.

11. The reactor of claim 1, further including a nanostructure product collector.

16. The method of claim 11, wherein the plasma-forming gas includes hydrogen gas.

12. A method for producing metal oxide nanostructures, comprising:

a) delivering a plasma-forming gas substantially longitudinally into a dielectric tube;

b) delivering a sheath gas into the dielectric tube;

c) forming a plasma by applying microwave energy to the plasma-forming gas;

d) delivering a metal powder into the dielectric tube; and

e) reacting the metal powder within the plasma to form metal oxide nanostructures.

13. The method of claim 12, wherein the plasma-forming gas includes argon.

14. The method of claim 12, wherein the plasma-forming gas includes an oxidative gas.

15. The method of claim 12, wherein the plasma-forming gas includes water vapor.

17. The method of claim 12, wherein the sheath gas is air.

18. The method of claim 12, wherein the sheath gas is delivered into the dielectric tube to form a helical sheath gas path.

19. The method of claim 12, wherein the power of microwave energy applied to the plasma-forming gas is about 300 watts to about 8 kilowatts.

20. The method of claim 12, wherein the metal powder consists of metal powder having a particle diameter of less than about 20 microns.

21. The method of claim 12, wherein the metal powder consists of metal powder having a particle diameter of less than about 1 micron.

22. The method of claim 12, further including entraining the metal powder within the plasma-forming gas.

23. The method of claim 12, wherein a portion of the metal powder delivered to the dielectric tube does not react to form metal oxide nanostructures and further including separating nanostructures from a stream of nanostructures and unreacted metal powder.

24. The method of claim 12, wherein a portion of the metal powder delivered to the dielectric tube does not react to form metal oxide nanostructures and further including recycling unreacted metal powder into the plasma.

25. The method of claim 12, further including delivering a bulk of the metal power substantially into the center of the plasma.

26. The method of claim 12, wherein the metal powder is delivered into the dielectric tube via a cooled metal powder delivery system, the cooled metal powder delivery system including a conical funnel.

27. The method of claim 12, wherein the metal powder is selected from a group consisting of tin, zinc, tungsten, titanium, iron, gallium, indium, bismuth, niobium, aluminum, vanadium, copper, and combinations thereof.

28. The method of claim 12, further including the step of vaporizing the metal powder within the plasma to form metal oxide nanoparticles.

29. The method of claim 12, further including the step of melting the metal powder within the plasma to form metal oxide nanowires.