By Joshua Ostrer
Students and professors in Union’s Departments of Chemistry and Mechanical Engineering are researching a very curious material: aerogels.
Student researchers Leah Smith ’14, Aude Bechu ’16 and Ryan Bouck ’16 and Professors Ann Anderson and Mary Carroll prepared a presentation for the American Chemistry Society entitled “Fabrication and Characterization of Vanadia-Silica Aerogels.”
According to their presentation, “Aerogels are highly porous, ceramic materials that are more than 90 percent air by volume. Aerogels have many unique properties, including the lowest density of any known solid, high surface area, high porosity, etc.
“All of these properties make aerogels attractive materials in various applications, including automotive catalysis,” the presentation continued
Aerogels have actually been around since 1931, but their potential uses are still being discovered.
In 1999, NASA employed the use of aerogels in its “Stardust” satellite, which used aerogels to capture small particles that trailed behind the paths of comets, to be used for later observation on Earth.
But Union students and faculty are exploring more earthly applications for the curious material.
“For years, the lab has worked on a variety of projects, such as characterizing this material, compressive testing, analyzing its thermal conductivity, researching its application in window panes, drug delivery, its catalytic capabilities and the list goes on and on,” said Junior Rivas ’14.
“The literature shows that they [aerogels] could potentially catalyze automotive exhaust remediation. Currently, catalytic converters in cars use precious metals that are both rare and expensive to catalyze, or speed up, the conversion of dangerous exhaust gases like hydrocarbons, nitrous oxides and carbon monoxide to common gases such as water vapor, oxygen, nitrogen and carbon dioxide,” said Leah Smith.
Catalytic converters, which are a crucial element in limiting harmful automotive emissions, are used in cars around the world today, but the device is plagued by a concerning limitation.
The standard three-way catalytic employs the use of rare and expensive metals like platinum ($13,000 per 100 grams), rhodium ($13,000 per 100 grams) and palladium ($1,571 per 100 grams).
However, research on aerogels, conducted at Union, suggests that the material could replace the elusive and expensive metals in catalytic converters. This would save car manufacturers both money and mineral.
Leah Smith finds aerogels interesting beause of their unique combination of properties.
“They’re the lightest solids on earth — the ones I make are about a tenth to a twentieth the density of water. They have incredibly high surface area — a gram of one of my aerogels has the same surface area as 2.3 tennis courts.
“And their surface area is attributable to their nanoporous structure — aerogels are 90 to 99 percent air by volume, so they’re mostly just holes, which is also what makes them so light.
“They can also be tuned to have other properties such as thermal, electrical and acoustic insulative abilities, catalytic properties, hydrophobicity, attraction or repulsion to other chemicals besides water and transparency.”
But how are the aerogels performing as catalytic converters?
Nickel-aluminum aerogels, which have already been tested here at Union. catalyzed up to 80 percent of carbon monoxide, up to 50 percent of hydrocarbons but only 10 percent of nitric oxide.
However, students will soon be conducting tests on vanadium-silicon aerogels, in the hopes that it will yield better results in catalyzing nitric oxide.
If the tests are successful, the vanadium-silicon aerogel would be an attractive alternative to current catalytic converters. Vanadium costs only $220 per 100 grams and silicon only $5.40 per 100 grams.
Union students and faculty are attempting to solve real world problems with aerogels, and it will be interesting to see how successful they are.
In the words of Junior Rivas, “Aerogels are important for two reasons: first, they are versatile, and second, this material has been around for a long time and new applications are still being discovered, meaning that there is still a lot to be learned from aerogels.”
Be on the lookout for how aerogels may impact your future.