Carbon nanotubes are a cutting-edge component used in the fields of electronics, medicine and industrial design due to their size, strength and electrical properties. However during their production, large amounts of greenhouse gases, including hazardous air pollutants, are released into the atmosphere. On top of that, several hundred tons of chemicals are used in their manufacturing. However in a paper published last week by ACS Nano, researchers reported that they have devised a method that reduces the harmful by-products of carbon nantube production by a factor of 100.
The new method features a step where carbon-based gases are heated and key reactive “ingredients” are introduced that reduce pollutants while decreasing the amount of energy used in the production of carbon nanotubes. Desiree Plata, who led the research between 2007 and 2009 as a doctoral student in MIT’s joint program with the Woods Hole Oceanographic Institution, said of the method, “We were able to do all of this and still have good CNT growth”.
Plata and the other researchers discovered that during the standard process for manufacturing carbon nanotubes, factories combine hydrogen with a “feedstock gas,” such as methane, carbon monoxide or ethylene. They then heat this combination in a reactor that contains a metal catalyst like nickel or iron, which then forms the nanotubes. However, during this process many unreacted compounds (which can amount to up to 97%) are then released into the atmosphere.
Plata and her team realized that not all of these components were crucial to the manufacture of nanotubes, so they combined unheated ethylene and hydrogen with 40 different compounds one by one, to see which ones were needed for nanotube creation. Their experiment saw a major reduction in emissions and energy consumption, as room-temperature alkynes were used in the process.
Plata said that their research could lead to “significant cost savings” for manufacturers. While it will take several years for manufacturers to adopt the new methods, several companies such as Nanocomp Technologies, have said they will look at trying to minimize the environmental impact of nanotube production.