In the late 1940s, Princeton University professors Walter Kauzmann and Henry Eyring formed a theory that all alkanes have a universal viscosity near their melting points. This has been cited over 3,000 times – only to be disproved by researchers from the University of Illinois at Urbana-Champaign, opening doors for a faster transport of gas.
They were able to videotape the molecular movement of alkanes, the major component of petroleum and natural gas, and found that the thickness of liquid alkanes can be significantly reduced. This allows for a marked increase in the substance’s rate of flow.
Yang Zhang, assistant professor of nuclear, plasma, and radiological engineering (NPRE) and Beckman Institute at Illinois, led this research.
“Alkane is basically a chain of carbon atoms,” he said. “By changing one carbon atom in the backbone of an alkane molecule, we can make it flow 30 times faster.”
This could mean that crude oil and gasoline could be transported across a country 30 times faster, and shortening the usual minutes of filling a tank of gas to only a few seconds.
Good thing that Zhang and his team challenged the classical Kauzmann-Eyring theory.
Zhang shared, “The classical Kauzmann-Eyring theory of molecular viscous flow is over simplified. It seems some chemistry textbooks may need revisions.”
They discovered that there is a distinct odd-even effect of the liquid alkane dynamics, which was not expected from them. It is only known in basic organic chemistry that solid alkanes have that odd-even effect, that is, the difference in the periodic packing of odd- and even-numbered alkane solids results in odd-even variation of their densities and melting points. But because liquid have the lack of periodic structures, this property was not thought to be possible – until now.
It was made possible thanks to the high flux neutron sources at the National Institute of Standards and Technology (NIST) and Oak Ridge National Laboratory (ORNL), and the super high-speed (at the pico-second, 1 trillionth of a second) and super high-resolution (at the nano-meter, 1 billionth of a meter) “video cameras” making use of neutrons to take movies of the molecules.
“A neutron ‘microscope’ is the major breakthrough in materials research and we use it to look at everything. There are things we’ve never seen before,” Zhang explained.
Applications of this discovery are not only on the delivery of petroleum but also in chemical processes like lubrication, diffusion through porous media, and heat transfer.
The details of their research “Dynamic Odd-Even Effect in Liquid n-Alkanes near Their Melting Points” can be found in the German publication Angewandte Chemie International Edition.
