Method producing metal nanopowders by decompositon of metal carbonyl using an induction plasma torch
View Patent ↗A process for synthesizing metal nanopowders by introducing metal carbonyl into an induction plasma torch. By taking advantage of the much lower dissolution temperature of carbonyl as opposed to the high melting temperature of conventional metal powder feeds less torch power is required. Moreover, in contrast to current powder production techniques utilizing electrode based plasma torches, the induction plasma torch does not introduce contaminants into the nanopowder.
1. A process for producing nanopowder comprising:
a) providing metal carbonyl;
b) introducing the metal carbonyl into an induction plasma torch;
c) causing the metal carbonyl to decompose within the induction plasma torch and form nanopowder comprising metal particles;
d) quenching the nanopowder with a quench gas in a reactor disposed downstream from the plasma torch; and
e) collecting the nanopowder,
wherein the metal particles are substantially spherical.
2. The process according to claim 1 wherein the metal carbonyl is selected from at least one of the group consisting of nickel carbonyl, iron carbonyl, copper carbonyl, cobalt carbonyl, chromium carbonyl, molybdenum carbonyl, tungsten carbonyl, and ruthenium carbonyl.
3. The process according to claim 1 wherein the metal carbonyl is mixed with a carrier gas.
4. The process according to claim 3 wherein the carrier gas is selected from at least one of the group consisting of helium, argon, nitrogen, hydrogen, and carbon monoxide.
5. The process according to claim 1 wherein a plasma gas is introduced into the plasma torch.
6. The process according to claim 5 wherein the plasma gas is selected from at least one of the group consisting of helium, argon, nitrogen and hydrogen.
7. The process according to claim 1 wherein a sheath gas is introduced into the plasma torch.
8. The process according to claim 7 wherein the sheath gas is selected from at least one the group consisting of helium, argon, nitrogen and hydrogen.
9. The process according to claim 1 wherein the quench gas is selected from at least one of the group consisting of argon, nitrogen, oxygen, ammonia and methane.
10. The process according to claim 1 wherein the metal carbonyl is subjected to a temperature of about 3,000-1,000 K in the induction plasma torch.
11. The process according to claim 1 wherein the metal carbonyl resides in the induction plasma torch for about 0.001-10 seconds.
12. The process according to claim 1 wherein the nanopowder particles are filtered.
13. The process according to claim 1 wherein the temperature of the induction plasma torch is 11,000 K.
14. The process according to claim 1 wherein the metal carbonyl is a gas.
15. The process according to claim 1 wherein the metal carbonyl is a liquid.
16. The process according to claim 1 wherein the metal particles have a typical mean particle diameter in the range of about 1 to 100 nm.