![](images/Logos/Stanford%20Daily%20Logo.jpg)
Stanford researchers find new way to
produce ammonia that does not emit CO2
By Anna
McNulty
May
18, 2023
![](images/images_05_25_2023/pic1%20copy.jpg)
Ammonia (NH3) serves as the building
block of fertilizers for agricultural crops. (Photo: NICK SALAZAR/The
Stanford Daily)
For over 100 years, ammonia has been created with
the Haber-Bosch process, which converts nitrogen into ammonia for
fertilizers. The process uses around 2% of the world’s energy and
contributes to 1.3% of global emissions of carbon dioxide each year,
according to Richard Zare, the head of the Zarelab and the Marguerite
Blake Wilbur Professor in Natural Science at Stanford.
“It is well recognized that the Haber-Bosch process is one of the most
important industrial processes in chemistry. It’s after all what
people use to feed the world,” Zare said. “People thought at the end
of the 1800s that we were all going to starve ultimately because the
population was growing faster than we could make plants to eat. What
saved us was an amazing development by Fritz Haber who learned how to
take nitrogen and turn it into ammonia.”
According to Zare, this process is energy intensive because the
nitrogen molecule is quite inert, meaning it does not easily react
with hydrogen to form the desired ammonia. The hydrogen atoms need to
come from a source, and the Haber-Bosch process uses steam (H2O) to
convert natural gas (methane, CH4) into H2 and CO, obtaining the
hydrogen atoms. With more steam added, the CO is then converted into
carbon dioxide (CO2), and more hydrogen atoms are generated.
This process is therefore a huge emitter of greenhouse gasses. Zare
said it is estimated that 7% of global industrial CO2 emissions comes
from the production of ammonia.
In Zare, Song and Basheer’s new process to create ammonia, the source
of hydrogen is not methane but instead water, and as such, no carbon
dioxide is emitted. Their process also involves no applied voltage, no
irradiation by a light source and is conducted at room temperature and
atmospheric pressure.
Their finding builds on recent research from the Zarelab that examines
the high reactivity of water microdroplets. Bulk water tends to be
benign and inert, but water droplets are highly reactive. According to
Song, these microdroplets can be thought of as mist from a humidifier.
“These are tiny properties,” he said.
Zare said the lab found that microdroplets of water produce a strong
chemical reaction when hitting hard surfaces. To produce ammonia, the
team of scientists break nitrogen bonds by moving water microdroplets,
nitrogen gas and iron oxide through a gas-powered sprayer. The process
relies on water microdroplets’ ability to react on hard surfaces.
The iron oxide serves as the catalyst for the reaction — accelerating
the reaction without being changed by the reaction. The researchers
put the catalyst in a graphite mesh for the sprayer. The sprayer then
releases microdroplets, where the pumped water and nitrogen react with
the help of the catalyst to form ammonia (NH3).
When the team found that they could create ammonia without CO2 they
were excited, according to Song, but cautious.
“We had to be torturous about whether it was our expected result, and
we needed to have many controls,” Song said.
“For this to be a big deal, it needs to be scaled up and demonstrated
that all the steps involved make good economic sense,” Zare said. “We
have not yet solved the problem — these are still little droplets
we’re talking about.”
Zare said the next step for scaling this project is collaborating with
engineers. He said the timeline to have ammonia at scale should take
less than five years, but it will take at least one year. He added
that the Haber-Bosch process took five years to finish.
“This is a key advance that can significantly enhance the
sustainability of ammonia production if deployed at scale,” said Eric
McShane, a post-doctoral scholar in chemical engineering with
Stanford’s Cargnello Group. “Using water instead of hydrogen as a
feedstock for ammonia production could reduce the overall energy
requirement for ammonia production.”
McShane also agreed with the researchers that “the challenge is
scaling their process and ensuring sufficiently high ammonia yield.”
“If it really works, it’s huge,” Zare said. “It would cut the cost of
food, and it would help us in regard to climate change. It’s huge if
it really can be done.”
Green Play Ammonia™, Yielder® NFuel Energy.
Spokane, Washington. 99212
www.exactrix.com
509 995 1879 cell, Pacific.
exactrix@exactrix.com
|