Grantee Research Project Results
Final Report: Combinatorial Screening of High-Efficiency Catalysts for Large-Scale Production of Pyrolytic Carbon Nanotubes
EPA Contract Number: 68D02028Title: Combinatorial Screening of High-Efficiency Catalysts for Large-Scale Production of Pyrolytic Carbon Nanotubes
Investigators: Sun, Ted X.
Small Business: Intematix Corporation
EPA Contact: Richards, April
Phase: I
Project Period: April 1, 2002 through September 1, 2002
Project Amount: $69,957
RFA: Small Business Innovation Research (SBIR) - Phase I (2002) RFA Text | Recipients Lists
Research Category: SBIR - Pollution Prevention , Nanotechnology , Pollution Prevention/Sustainable Development , Small Business Innovation Research (SBIR)
Description:
The objective of this Phase I research project was to decrease the production cost of carbon nanotube (CNT) by three orders of magnitude-from the current level of approximately $100/g to $100/kg for multiple-walled carbon nanotube (MWNT), and approximately $1,000/g to $1,000/kg for single-walled carbon nanotube (SWNT) (see the updated price information from the "nanotube sources and products section" of "The Nanotube Site" at http://www.pa.msu.edu/cmp/csc/nanotube.html Exit ). Intematix, Inc., has identified the lack of efficient and selective catalysts and processes in mass producing high-purity CNT as the critical barrier in reaching the project goal. Therefore, the Phase I research project focused on discovering highly efficient CNT catalysts for a high-volume chemical vapor deposition (CVD) production process.
Intematix, Inc., successfully developed, implemented, and validated a highly efficient combinatorial process for high-throughput screening (HTS) the CNT catalysts. The process integrates the design and fabrication of catalyst libraries that contain hundreds to thousands of different alloy compositions, with the catalytic synthesis and scanning electron microscopy (SEM) screening of as-grown CNT to search for the best catalyst alloy compositions that afford the highest yield for low-cost production of high quality CNT.
With the combinatorial process, more than 10,000 distinct catalyst alloy compositions were synthesized during Phase I. Their catalytic properties were screened in making MWNT by directly observing the MWNT grown on each catalyst composition under a high-resolution electron microscope. Several highly active catalysts were discovered that start producing CNT at a record low temperature of 400°C with ethylene-reactant gas. The typical temperature required for synthesizing CNT with ethylene is in the range of 550-750°C (Ebbesen TW, ed. Carbon nanotubes: preparation and properties. Boca Raton: CRC Press, 1997.). Some newly identified catalysts were validated in a conventional bulk powder form with high catalytic yields of ~180 over ~120 from the best-known catalyst (defined as the net weight ratio of CNT over catalyst) (Manderville W, et al. Fibrils. U.S. Patent # 5,500,200. Assigned to Hyperion Catalysts International, 1996). In addition, some CNT with novel morphologies were discovered, such as a DNA-like double-helix CNT and carbon nanobelt made by a thin film catalyst. The discovery of the highly efficient catalysts will allow Intematix, Inc., to reach the CNT cost goal in Phase II.
The goal of this Phase I SBIR project was to develop an HTS technology for efficient search of catalysts to produce high-quality carbon nanotubes with high yield. The technical objectives of Phase I were to:
- Establish and validate a full-scale HTS capability for carbon nanotube catalysts in 2 months from the start of the project.
- Synthesize, screen, and document more than 10,000 distinct alloy compositions for potential advanced CNT catalyst materials.
- Identify three nanotube catalyst "leads" from the laboratory scale of Phase I.
- Validate at least one superior carbon nanotube catalyst composition from
the leads and prove that it meets the following criteria:
- It makes high quality and uniform carbon nanotubes with an average diameter of less than 40 nm.
- It makes such nanotubes at a temperature of less than 800°C with ethylene or acetylene at ambient pressure.
- It has a catalytic conversion rate of more than 200 times.
- The as-synthesized product has nanotube purity of more than 80 percent.
- It allows the cost target of producing carbon nanotube to be within $100/kg.
Summary/Accomplishments (Outputs/Outcomes):
Intematix, Inc., developed a set of fully functional combinatorial tools for HTS of advanced catalysts for synthesizing CNT. This set of tools integrates the design, fabrication, and synthesis of libraries of catalysts, with the on-site nanotube growth and SEM screening of the nanotube in evaluating the corresponding catalyst performance. Libraries of alloys with hundreds to thousands of different compositions were generated using Intematix, Inc.'s proprietary combinatorial ion-beam sputtering (CIBS) deposition system. The alloys in a library were synthesized together under controlled atmosphere, and all the alloys in a library were subjected simultaneously under gaseous reactants (e.g., ethylene and H2) to produce CNT. Finally, the carbon deposit on each alloy composition was observed under SEM to evaluate the performance of the alloy composition in catalyzing the synthesis of MWNT. During the Phase I research project, the existing CIBS system was improved to accommodate air-sensitive metal targets in making alloys-a miniature CVD system was built for synthesizing and testing the alloys in a library in making CNT. All of the components in the combinatorial cycle have been validated and used in the combinatorial search of nanotube catalysts.
Using the established combinatorial tools tailor-built for nanotube catalysts, more than 10,000 different alloy compositions were generated from the following group of elements: Fe, Co, Ni, Ti, Ta, V, Cr, Mn, Mo, and Al. The majority of these metals are nonprecious transitional metals because the cost reduction is a primary goal of the project, and all of the currently known carbon nanotube catalysts contain transitional metals as critical components. This huge set of alloy compositions was made using CIBS, reacted under ethylene gas, and screened with SEM to evaluate the alloy performance in making high-quality MWNT. Many interesting composition-catalytic property relationships were discovered by such combinatorial processes, which demonstrated the high efficiency of the combinatorial approach in discovering advanced nanotube catalysts.
From the HTS search, more than three new, highly active catalysts have been identified that are superior to the reported state-of-the-art nanotube catalysts (e.g., Fe-Mo catalyst system from Hyperion Catalysts International) in the catalytic activity and the yield and quality of MWNT under identical CNT reaction conditions. For example, Hyperion's catalyst synthesizes nanotube at a temperature of more than 600°C with ethylene, while Intematix, Inc.'s leading catalysts start making nanotubes at temperatures as low as 400°C in ethylene.
By supporting these new catalysts with adequate catalytic support (e.g., nanometer-sized boron nitride particles, Al2O3 nanoparticles, micron-sized carbon particles), their catalytic performance in making CNT was validated. It was found that:
- They make high-uniformity and high-purity carbon nanotubes with an average
diameter ranging from 10 nm to a few hundred nanometers. Nanotubes of custom-specified
diameter with the choice of different catalysts can be made.
- The reaction temperature can be as low as 500°C for most new catalysts
with ethylene, which is far below 800°C. An even lower reaction temperature
is expected with acetylene, because acetylene is more reactive than ethylene.
- The catalytic yields (defined as the net weight ratio of CNT over catalyst)
of some active catalysts reached 158. Recent improvement on the processing
conditions on these new catalysts has resulted in further increase of the
catalytic yields to a value of greater than 200, using carbon particles as
catalyst support.
- The cost estimate with the new CNT catalysts of high yield indicates that the cost target of $100/kg is feasible in the Phase II effort of MWNT production, with the new catalysts.
Conclusions:
With the advanced CNT catalysts discovered in Phase I, the CNT cost target of the SBIR project will be reached by designing and developing a highly efficient catalytic CVD production process for high-volume and high-purity CNT. The established combinatorial screening technique will be further applied to identify high-yield SWNT catalysts. In addition, a continuous chemical vapor CNT growth pilot facility will be set up to reach the goal of approximately $100/lb. Finally, Intematix, Inc., will explore the process to disperse CNT into several commercially important plastics to form composite materials, and will work with potential partners (e.g. Ferro Corp) to commercialize such low-cost and highly functional composite materials in automobile body panel applications, which will enable a very clean "primerless" electrostatic coating process.
Journal Articles:
No journal articles submitted with this report: View all 4 publications for this projectSupplemental Keywords:
catalyst, pyrolytic carbon nanotubes, CNT, multiple-walled carbon nanotube, MWNT, single-walled carbon nanotube, SWNT, chemical vapor deposition, scanning electron microscopy, SEM, high-throughput screening, catalytic conversion rate, combinatorial ion-beam sputtering deposition system, CIBS, SBIR, RFA, Scientific Discipline, Air, particulate matter, Environmental Chemistry, indoor air, Engineering, Chemistry, & Physics, Environmental Engineering, particulates, indoor air pollution control, ambient air quality, emission control strategies, aerosol particles, indoor VOC compounds, filtration, pollution control technologies, pyrolytic carbon nanotubes, ambient air, carbon nanotubes, workplace, air pollution, catalysts, emissions, particle pollutants, environmental contaminants, nanoparticles, Volatile Organic Compounds (VOCs), indoor air quality, nanotube, air quality, aerosols, ambient pollution control, nanoporous filtersSBIR Phase II:
Low-Cost Catalytic Production of High-Quality Carbon Nanotube for Advanced Conductive Composites | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.