Reactors for producing inorganic fullerene-like tungsten disulfide hollow nanoparticles and nanotubes
The present invention is related to an apparatus for the production of inorganic fullerene-like (IF) nanoparticles and nanotubes. The apparatus comprises a chemical reactor, and is further associated with a feeding set up and with a temperature control means for controlling the temperature along the reaction path inside the reactor so as to maintain the temperature to be substantially constant. The invention is further directed to a method for the synthesis of IF-WO3 nanoparticles having spherical shape and having a size up to 0.5 mu m and nanotubes having a length of up to several hundred mu m and a cross-sectional dimension of up to 200 nanometer.
1. A synthetic method of production of WS 2 fullerene-like nanoparticles and nanostructures from WO 3 metal oxide powder and H 2 and H 2 S reacting gases, said method comprising the steps of:
(i) feeding a first mixture of a reacting tungsten oxide powder and an inert gas with a predetermined feeding rate downwardly into the top of a vertical flow line extending into the inside of a vertical chemical reactor such that a lower end of the vertical flow line is located inside the vertical chemical reactor, and providing a flow of a mixture of the H 2 and H 2 S reacting gases along said vertical chemical reactor, so as to allow interaction of the flowing tungsten oxide powder and the reacting gases in a reaction path located in the vertical chemical reactor;
(ii) controlling temperature inside the chemical reactor so as to provide a predetermined temperature profile along the reaction path; and
(iii) collecting the formed WS 2 nanostructures at a bottom portion of the vertical reactor,
the method thereby providing a solid-gas reaction between the reacting gases and the tungsten oxide powder during the flow through and along the reaction path, resulting in the formation of WO 3-x , clusters coated by at least one layer of WS 2 , and further exchange of oxides by sulfides in inner parts of the clusters, thereby causing formation of WS 2 nanostructures.
2. The method according to claim 1 , wherein the feeding rate of the reacting tungsten oxide powder is selected in accordance with the dimensions of the chemical reactor, thereby obtaining the WS 2 nanostructures in the form of IF-nanoparticles, or a combination of IF-nanoparticles and nanotubes.
3. The method according to claim 2 , wherein the feeding rate ranges between about 3 mg/min to about 120 mg/min, the concentration of the H 2 gas being from about 0.2% (w/v) to about 7% (w/v) and the concentration of the H 2 S gas being from about 0.1% (w/v) to about 6% (w/v).
4. The method according to claim 3 , wherein the formed nanostructures contain a combination of nanoparticles and nanotubes.
5. The method according to claim 2 , wherein the feeding rate ranges between about 3 mg/min to about 40 mg/min, with the concentration of the H 2 and H 2 S gases ranging from about 0.2% to about 4% (w/v).
6. The method according to claim 5 , wherein the formed IF-WS 2 nanostructures contain nanoparticles, each having a substantially perfect spherical shape and having a size up to 0.5 μm.
7. The method according to claim 2 , wherein the feeding rate ranges between about 40 mg/min and about 120 mg/min, with the concentration of the H 2 and H 2 S gases from about 3% to about 7% (w/v).
8. The method according to claim 7 , wherein the formed WS 2 nanostructures contain a combination of IF-nanoparticles and nanotubes, the nanotubes each having a cross-sectional dimension of up to 200 nanometer.
9. The method according to claim 2 , wherein the feeding rate ranges between about 3 mg/min to about 40 mg/min, with the concentration of the H 2 gas from about 0.2% to about 4% and the concentration of the H 2 S gas from about 0.2% to about 4% (w/v)
10. The method according to claim 9 , wherein the formed WS 2 nanostructures contain a combination of nanoparticles and nanotubes, the nanotubes having a length of up to several hundred μm and a cross-sectional dimension of up to 200 nanometer.
11. The method according to claim 1 , wherein said temperature within the reaction path is maintained at a constant temperature within the range of about 750° C. to about 850° C.
12. The method according to claim 1 , wherein the flow of the mixture of the H 2 and H 2 S reacting gases in said feeding step (i) is in a downward direction into the top of the vertical chemical reactor.
13. The method according to claim 1 , wherein the flow of the mixture of the H 2 and H 2 S reacting gases in said feeding step (i) is in an upward direction from the bottom of the vertical chemical reactor, thereby creating a fluidized bed of said powder in said reacting gases.