KR-20260066152-A - Catalyst for carbon nanotube manufacturing

Abstract

A method for forming carbon nanotubes that may include the following steps: volatilizing a metal alloy in a plasma to form an active catalyst; flowing the active catalyst and a carbon source into a floating catalyst chemical vapor deposition reactor; and pyrolyzing at least a portion of the carbon source on the active catalyst in the pyrolysis zone of the floating catalyst chemical vapor deposition reactor to form carbon nanotubes on the active catalyst.

Inventors

• 리우 소피
• 콜비 로버트 제이
• 존슨 로버트 에이
• 마 닝
• 파일 스티븐
• 라만 수마티
• 터르코즈 엠레
• 왕 건
• 미첼 조나단

Assignees

• 엑손모빌 테크놀로지 앤드 엔지니어링 컴퍼니

Dates

Publication Date

20260512

Application Date

20240813

Priority Date

20230913

Claims (20)

1. As a method for forming carbon nanotubes, A step of volatilizing a metal alloy in plasma to form an active catalyst; A step of flowing an active catalyst and a carbon source into a floating catalyst chemical vapor deposition reactor; and A step of forming carbon nanotubes on an active catalyst by pyrolyzing at least a portion of the carbon source on the active catalyst in the pyrolysis zone of a suspended catalyst chemical vapor deposition reactor. A method for forming carbon nanotubes including
2. A method according to claim 1, wherein the metal alloy comprises at least two metals selected from the group consisting of iron, nickel, cobalt, manganese, tungsten, molybdenum, and combinations thereof.
3. A method according to claim 1 or 2, wherein the metal alloy comprises iron and about 10 weight% to about 25 weight% nickel.
4. A method according to any one of claims 1 to 3, wherein the metal alloy comprises iron and about 12 weight% to about 25 weight% of cobalt.
5. A method according to any one of claims 1 to 4, wherein the metal alloy comprises iron and about 10 weight% to about 25 weight% molybdenum.
6. A method according to any one of claims 1 to 5, wherein the metal alloy comprises iron, about 10 weight% to 25 weight% manganese and about 12 weight% to 25 weight% cobalt.
7. A method according to any one of claims 1 to 6, wherein the metal alloy further comprises a support selected from the group consisting of activated carbon, alumina, zeolite, silica, titanium dioxide and combinations thereof.
8. A method according to any one of claims 1 to 7, wherein the active catalyst and the carbon source flow turbulently through a floating catalyst chemical vapor deposition reactor.
9. A method according to claim 8, wherein the Reynolds number of the active catalyst and carbon source flowing through the floating catalyst chemical vapor deposition reactor is in the range of about 5,000 to about 20,000.
10. A method according to any one of claims 1 to 9, wherein the active catalyst is introduced into a floating catalyst chemical vapor deposition reactor without quenching.
11. A method according to any one of claims 1 to 10, wherein the carbon source comprises a C1-C10 hydrocarbon.
12. A method according to any one of claims 1 to 11, wherein the carbon source comprises a C1-C10 alcohol.
13. A method according to any one of claims 1 to 12, wherein the carbon source comprises ethane vapor cracker effluent and/or fluidization catalyst cracker off-gas.
14. A method according to any one of claims 1 to 13, further comprising the step of introducing a carrier gas into the plasma, wherein the feed to the suspended catalyst chemical vapor deposition reactor comprises an active catalyst suspended in the carrier gas.
15. A method according to claim 14, wherein the carrier gas comprises at least one gas selected from the group consisting of inert gases, hydrogen, helium, and combinations thereof.
16. As a reaction system for carbon nanotube formation, Carbon source; As a floating catalyst chemical vapor deposition reactor, Pyrolysis zone; An inlet through which a carbon source flows into the pyrolysis zone; and A heater configured to heat the pyrolysis zone to the pyrolysis temperature A floating catalyst chemical vapor deposition reactor comprising, wherein the floating catalyst chemical vapor deposition reactor is configured to pyrolyze a carbon source in a pyrolysis zone to produce pyrolyzed carbon; Metal alloy; and A plasma generator configured to generate plasma It includes, wherein the metal alloy is placed within the plasma so that the plasma volatilizes the metal alloy to form an active catalyst; A reaction system for carbon nanotube formation in which a plasma generator and a suspended catalytic chemical vapor deposition reactor are fluidically coupled to bring the active catalyst and pyrolyzed carbon into contact in the pyrolysis region.
17. A reaction system according to claim 16, wherein the metal alloy comprises at least two metals selected from the group consisting of iron, nickel, cobalt, manganese, tungsten, molybdenum, and combinations thereof.
18. A reaction system according to claim 16 or 17, wherein the metal alloy comprises iron and about 10 weight percent to about 25 weight percent nickel.
19. A reaction system according to any one of claims 16 to 18, wherein the metal alloy comprises iron and about 12 weight% to about 25 weight% of cobalt.
20. A reaction system according to any one of claims 16 to 19, wherein the metal alloy comprises iron and about 10 weight% to about 25 weight% molybdenum.

Description

Catalyst for carbon nanotube manufacturing This application relates to a system and method for manufacturing carbon nanoscale structures, such as carbon nanotubes or carbon nanofibers. Floating catalyst chemical vapor deposition (FC-CVD) is a process for manufacturing carbon nanotubes (CNT). A typical FC-CVD process involves introducing a feed containing a pre-catalyst and a carbon source into a tubular reactor at a relatively high temperature of approximately 1,000°C or higher. In the tubular reactor, the pre-catalyst is converted into an active catalyst, and the carbon source is decomposed to produce a reactive carbon intermediate, which reacts further with the catalyst to form carbon nanotubes. The pre-catalyst is typically an organometallic iron source, such as ferrocene. Attempts to scale up existing reactors for carbon nanotube manufacturing can present various challenges. First, as the reactor diameter increases, it becomes increasingly difficult—though not physically impossible—to transfer sufficient heat through the reactor walls to maintain the temperature required to thermally decompose the precatalyst and form the active catalyst. Furthermore, since the thermal decomposition temperature of a specific precatalyst may differ significantly from the reaction temperature required to manufacture carbon nanotubes, additional quenching gases and process steps are necessary, thereby complicating the reactor design. For instance, attempting to cool the gas flow within the reactor after the active catalyst has formed may result in the catalyst surface temperature becoming too low, preventing effective catalyzing of carbon nanotube formation. Additionally, as the precatalyst decomposes, iron (or other metals) from the catalyst precursor tend to deposit on the reactor walls. This can lead to a loss of more than 50 mol% of metal from the precatalyst. Moreover, once this metal deposition begins, coke formation is observed on the walls of existing reactors. Deposition occurs because, when the precatalyst is decomposed at temperatures generally between 700°C and 1000°C, the resulting metal has higher phase stability as atoms deposited on the surface than as atoms remaining in a gaseous state. Consequently, when the precatalyst is heated to a temperature range of 700°C to 1000°C, metal may be deposited on the exposed surface. This metal deposition can continue until the temperature exceeds 1000°C, where metal atoms have higher phase stability in a gaseous state. In conventional FC-CVD reactors, a significant amount of metal is deposited on the reactor walls, which can reduce or minimize the amount of activated catalyst formed. Therefore, scaling up the FC-CVD process faces difficulties due to high costs and the low utilization efficiency of the total catalyst. In the FC-CVD process, since only a tiny fraction of the total catalyst is activated, a relatively high catalyst feed rate, a long reactor residence time, and a large reactor volume are required. outline The present invention discloses an exemplary method for forming carbon nanotubes, the method comprising the steps of: volatilizing a metal alloy in a plasma to form an active catalyst; flowing the active catalyst and a carbon source into a floating catalytic chemical vapor deposition reactor; and pyrolyzing at least a portion of the carbon source on the active catalyst in the pyrolysis zone of the floating catalytic chemical vapor deposition reactor to form carbon nanotubes on the active catalyst. Further disclosed herein is a carbon nanotube formation reaction system, wherein the system comprises a carbon source; a pyrolysis zone; an inlet through which the carbon source flows into the pyrolysis zone; a floating catalytic chemical vapor deposition reactor comprising a heater configured to heat the pyrolysis zone to a pyrolysis temperature; a metal alloy; and a plasma generator configured to generate a plasma, wherein the floating catalytic chemical vapor deposition reactor is configured to pyrolyze the carbon source in the pyrolysis zone to produce pyrolyzed carbon; the metal alloy is placed within the plasma so that the plasma volatilizes the metal alloy to form an active catalyst; and the plasma generator and the floating catalytic chemical vapor deposition reactor are fluidically coupled so that the active catalyst and the pyrolyzed carbon come into contact in the pyrolysis zone. These features and characteristics of the disclosed method and system of the present disclosure, as well as other features and characteristics and advantageous applications and/or uses thereof, will become apparent from the detailed description below. Refer to the attached drawings to assist those skilled in the art in manufacturing and using the subject matter of the present invention. FIG. 1 is an exemplary depiction of an FC-CVD process according to a specific embodiment of the present disclosure. FIG. 2 is a scanning electron microscope image of a carbon nanotube manufactur