Methods Reduce Cost, Enhance Quality of Nanotubes
- Sunday, 01 November 2009
To address these issues, Johnson awarded Phase I and II Small Business Innovation Research (SBIR) contracts to SouthWest NanoTechnologies Inc. (SWeNT), of Norman, Oklahoma, to pursue the development of a new nanotube production method. Founded in 2001, SWeNT is the offshoot of landmark research conducted by Daniel Resasco at the University of Oklahoma. Resasco pioneered a controlled catalytic method for creating nanotubes that is inherently scalable for mass production. During Resasco’s cobalt-molybdenum catalytic procedure—known as the CoMoCAT process—pure carbon monoxide (CO) flows through suspended cobalt and molybdenum catalyst particles in a device called a tubular fluidized bed reactor. At certain temperatures and pressure, the nanotubes are grown as the CO decomposes into carbon and carbon dioxide. By controlling the conditions and catalyst within the reactor, Resasco was able to grow significant, highly selective amounts of high-quality nanotubes within a couple of hours.
Using the NASA SBIR funding, SWeNT demonstrated that increasing the size of the fluidized bed reactor platform increased production capacity while decreasing cost. The SBIR support also provided another welcome outcome: higher quality nanotubes.
“When we invested in larger scale equipment, we also invested in more automation, instrumentation, and process controls,” says SWeNT CEO David Arthur. “That resulted in significant improvement in quality at the same time that we were expanding capacity and reducing cost.”
In 2008, SWeNT opened a commercial-scale nanotube manufacturing plant. Since beginning operations at the 18,000-square-foot facility, Arthur says, the company has experienced a hundredfold increase in production coupled with a tenfold reduction in cost. SWeNT now offers two single-walled carbon nanotube product lines, as well as customized orders for the company’s hundreds of customers.
“We are one of the only companies that is able to supply these materials in commercial quantities in North America,” says Arthur. “None of this would have happened without the original NASA SBIR funds to prove our production methods.”
Those production methods are the key to increasing output while lowering cost, Arthur notes. By controlling nanotube synthesis, SWeNT can selectively grow the nanotubes its clients want while avoiding an expensive, wasteful, time-consuming, and non-scalable sorting process. Using the CoMoCAT process, the company delivers nanotube orders that are routinely 95 percent carbon in composition, with more than 90 percent of that carbon in the form of nanotubes—all above typical industry outcomes.
SWeNT’s controlled synthesis capabilities have allowed it to provide customers with customized nanotubes for a wide range of new and developing technologies. The company has supplied diameter-specific nanotubes for use in reinforcing carbon fibers, with the potential to yield a material 17 times stronger than Kevlar for use in bulletproof body and vehicle armor. It is working with aerospace and nanomaterials clients to produce chirality-specific nanotubes—the goal, Arthur says, is to create the most electrically conductive carbon nanotubes in the world—for nanocomposite cable wiring to replace standard metal wiring in commercial aircraft. The company is exploring the use of its semiconducting nanotubes in the form of an ink, enabling the production of low-cost, printable electronics; applications include radio frequency identification, biological and chemical sensors, and electronic displays. Arthur foresees SWeNT nanotubes also enabling more affordable solar photovoltaic panels and solid-state lighting products that could have a dramatic impact on energy consumption.
SWeNT has set its sights on expanding its capabilities to also produce small-diameter, multiwalled carbon nanotubes for niche electrical applications, as well as building on its current single-walled nanotube success.