Apparatus and method for producing carbon nanofibers from light hydrocarbons
A process and apparatus for producing carbon nanofibers. The process comprises two stages. The first stage involves oxidizing light hydrocarbon with carbon dioxide or water, or oxygen, or a combination thereof to a mixture of hydrogen and carbon monoxide. The second stage involves converting the produced hydrogen and the carbon monoxide to carbon nanofibers and steam. In this way, greenhouse gases may be reduced by using carbon dioxide and methane (and/or other light hydrocarbons) as reactants; and useful products may be produced, such as Carbon NanoFibers (CNF).
1 . A process for producing carbon nanofibers, the process comprising:
in a first reactor, reacting a light hydrocarbon stream with an oxidizing agent to perform a reforming reaction to produce an intermediate gas stream comprising hydrogen and carbon monoxide; and
in a second reactor, converting, using a nanoparticle catalyst consisting of nanoparticles, the produced hydrogen and the produced carbon monoxide selectively to carbon nanofibers that build up inside the second reactor, and steam which exits the second reactor,
wherein the nanoparticles are formed on a support comprising barriers of filamentous oxide whiskers configured to restrict motion of the nanoparticles across a surface of the support and,
wherein the nanoparticles are chemically bonded to the support.
2 . The process of claim 1 , further comprising: separating, using a separator, unreacted portions of the CO 2 and the light hydrocarbon from the intermediate gas stream; and recycling the separated unreacted portions of CO 2 and the light hydrocarbon into the first reactor.
3 . The process of claim 2 , wherein the step of separating unreacted portions of the CO 2 and the light hydrocarbon from the intermediate gas stream from the first reactor is carried out using a membrane separator.
4 . The process according to claim 1 , wherein the first reactor is configured to enable dry catalytic reforming of the light hydrocarbon.
5 . The process according to claim 1 , wherein the reforming reaction in the first reactor is carried out at a temperature between about 480° C. and about 850° C., and at a pressure up to about 5 MPa.
6 . The process according to claim 1 , wherein the light hydrocarbon is methane.
7 . The process according to claim 1 , wherein the process comprises harvesting heat from the second reactor and supplying the harvested heat to the first reactor.
8 . The process according to claim 1 , wherein the unreacted portions of the oxidising agent and the light hydrocarbon are passed through the second reactor along with the produced hydrogen and the carbon monoxide.
9 . The process according to claim 1 , wherein the nanoparticles comprise one or more of Fe, Ni, Cu, Zn, Co, Mg, Mn and Mo.
10 . The process according to claim 1 , wherein a diameter of the nanoparticles is between 30-150 nm.
11 . The process according to claim 1 , wherein the reaction in the first reactor is configured to provide the hydrogen and the carbon monoxide in a molar ratio of between 0.5 and 1.2.
12 . The process of claim 1 , wherein the support is magnetic.
13 . The process of claim 1 , wherein the filamentous oxide whiskers comprise alumina.
14 . The process of claim 1 , wherein the filamentous oxide whiskers comprise zirconia.
15 . A process for producing carbon nanofibers, the process comprising:
in a first reactor, reacting a light hydrocarbon stream with an oxidizing agent to perform a reforming reaction to produce an intermediate gas stream comprising hydrogen and carbon monoxide; and
in a second reactor, converting, using a nanoparticle catalyst consisting of nanoparticles, the produced hydrogen and the produced carbon monoxide selectively to carbon nanofibers that build up inside the subsequent second reactor, and steam which exits the subsequent second reactor,
wherein the nanoparticles are formed on a support comprising barriers of filamentous oxide whiskers configured to restrict motion of the nanoparticles across a surface of the support, and
wherein the support is magnetic.
16 . The process of claim 15 , further comprising: separating, using a separator, unreacted portions of the CO 2 and the light hydrocarbon from the intermediate gas stream; and recycling the separated unreacted portions of CO 2 and the light hydrocarbon into the first reactor.
17 . The process according to claim 15 , wherein the first reactor is configured to enable dry catalytic reforming of the light hydrocarbon.
18 . The process according to claim 15 , wherein the reforming reaction in the first reactor is carried out at a temperature between about 480° C. and about 850° C., and at a pressure up to about 5 MPa.
19 . The process according to claim 15 , wherein the light hydrocarbon is methane.
20 . The process according to claim 15 , wherein the nanoparticles comprise one or more of: Fe, Ni, Cu, Zn, Co, Mg, Mn and Mo.
21 . The process according to claim 15 , wherein a diameter of the nanoparticles is between 30-150 nm.
22 . The process according to claim 15 , wherein the reaction in the first reactor is configured to provide the hydrogen and the carbon monoxide in a molar ratio of between 0.5 and 1.2.
23 . The process of claim 15 , wherein the filamentous oxide whiskers comprise alumina.
24 . The process of claim 15 , wherein the filamentous oxide whiskers comprise zirconia.