Researchers convert coal powder into graphite in a microwave

Researchers convert coal powder into graphite in a microwave

In a microwave, sparks are generated in a glass vial containing coal powder and copper foil as part of an experiment by UW researchers. They successfully converted the coal powder into nano-graphite, demonstrating a new and low-cost coal converting technology. Credit: YOUR photo

Using copper foil, glass containers, and a conventional household microwave, researchers at the University of Wyoming have shown that pulverized coal powder can be converted into higher-quality nano-graphite.

The discovery is another step forward in the effort to find alternative uses for Wyoming’s Powder River Basin coal, at a time when the demand for coal to generate electricity is declining due to concerns about climate change.

In a paper published in the journal Nanostructures and Nano ObjectsThe UW researchers report that they have created an environment in a microwave to successfully convert raw coal powder into nanographite, which is used as a lubricant and in items ranging from fire extinguishers to lithium ion batteries. This “one-step metal-aided microwave treatment method” is a novel approach that could represent a simple and relatively inexpensive coal conversion technology.

“This method provides a new way to convert abundant carbon sources into high-performance materials with environmental and economic benefits,” wrote the research team led by associate professor TeYu Chien of UW’s Department of Physics and Astronomy.

Others involved in the project were Professor Jinke Tang from the Department of Physics and Astronomy; Associate Professor Brian Leonard, in the chemistry department; Professor Maohong Fan, in the Petroleum Engineering Department and the School of Energy Resources; graduate students Rabindra Dulal, Nepal, Joann Hilman, Laramie, Wyo., Chris Masi, Syracuse, NY, and Teneil Schumacher, Buffalo, Wyo. and postdoctoral researchers Gaurab Rimal from Nepal and Bang Xu from China.

While previous research has shown that microwaves can be used to lower the moisture content of coal and remove sulfur and other minerals, most such methods require specific chemical pre-treatment of the coal. In their experiment, the UW researchers ground raw Powder River Basin coal into powder.

That powder was then placed on copper foil and sealed in glass containers with a gas mixture of argon and hydrogen before being placed in a microwave. A conventional microwave oven was chosen for its convenience and because it provided the desired radiation levels.

“By cutting the copper foil into the shape of a fork, the sparks were generated by the microwave radiation, generating an extremely high temperature of over 1800 degrees Fahrenheit in seconds,” said Masi, lead author of the paper. “This is why you shouldn’t put a metal fork in a microwave.”

The sparks created by the microwaves created the high temperatures required to convert the coal powder into polycrystalline graphite, with copper foil and hydrogen gas also contributing to the process.

While the experiment involved microwaves ranging from 3 to 45 minutes, the optimal duration was found to be 15 minutes.

The researchers say this new method of coal conversion can be refined and implemented on a larger scale to achieve both higher quality and quantity of nanographite materials.

“Finite graphite reserves and environmental concerns for the graphite extraction procedures make this method of converting coal to graphite a great alternative source for graphite production,” the scientists wrote.


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More information:
Christoffer A. Masi et al., Converting crude coal powder into polycrystalline nanographite by metal-assisted microwave treatment. Nanostructures and Nano Objects Volume 25, 2021, 100660, ISSN 2352-507X, doi.org/10.1016/j.nanoso.2020.100660

Provided by University of Wyoming

Quote: Researchers convert coal powder to graphite in microwave (2021, Jan 6) Retrieved Jan 6, 2021 from https://phys.org/news/2021-01-coal-powder-graphite-microwave-oven.html

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