Nav: Home

Cleaner, cheaper ammonia

April 24, 2019

Ammonia - a colorless gas essential for things like fertilizer - can be made by a new process which is far cleaner, easier and cheaper than the current leading method. UTokyo researchers use readily available lab equipment, recyclable chemicals and a minimum of energy to produce ammonia. Their Samarium-Water Ammonia Production (SWAP) process promises to scale down ammonia production and improve access to ammonia fertilizer to farmers everywhere.

In 1900, the global population was under 2 billion, whereas in 2019, it is over 7 billion. This population explosion was fueled in part by rapid advancements in food production, in particular the widespread use of ammonia-based fertilizers. The source of this ammonia was the Haber-Bosch process, and though some say it's one of the most significant achievements of all time it comes with a heavy price.

The Haber-Bosch process only converts 10 percent of its source material per cycle so needs to run multiple times to use it all up. One of these source materials is hydrogen (H2) produced using fossil fuels. This is chemically combined with nitrogen (N2) at temperatures of about 400-600 degrees Celsius and pressures of about 100-200 atmospheres, also at great energy cost. Professor Yoshiaki Nishibayashi and his team from the University of Tokyo's Department of Systems Innovation hope to improve the situation with their SWAP process.

"Worldwide, the Haber-Bosch process consumes 3 to 5 percent of all natural gas produced, around 1 or 2 percent of the world's entire energy supply," explained Nishibayashi. "In contrast, leguminous plants have symbiotic nitrogen-fixing bacteria that produce ammonia at atmospheric temperatures and pressures. We isolated this mechanism and reverse engineered its functional component - nitrogenase."

Over many years, Nishibayashi and his team used lab-made catalysts to try and reproduce the way nitrogenase behaves. Others have tried but their catalysts only produce dozens to several hundred ammonia molecules before they expire. Nishibayashi's special molybdenum-based catalyst produces 4,350 ammonia molecules in about four hours before it expires.

"Our SWAP process creates ammonia at 300-500 times the rate of the Haber-Bosch process and at 90 percent efficiency," continued Nishibayashi. "Factor in the gargantuan energy savings in the process and sourcing of raw materials and the benefits really show."

Anyone with the proper source materials can perform SWAP on a table-top chemistry lab, whereas the Haber-Bosch process requires large-scale industrial equipment. This could afford access to those who lack the capital to invest in such large, expensive equipment. The raw materials themselves are a huge saving in terms of cost and energy.

"A strong motivation was to make the SWAP process possible on a desktop scale. I hope to see this process democratize production of fertilizers," said Nishibayashi. "So it's not just about the upfront costs but also the continued cost and energy savings of raw materials. My team offers this idea to help agricultural practices in the places which need it the most."

SWAP takes in nitrogen (N2) from the air - as the Haber-Bosch process does - but the special molybdenum-based catalyst combines this with protons (H+) from water and electrons (e-) from samarium (SmI2). Samarium - also known as Kagan's reagent - is currently mined and is used up in the SWAP process. However samarium can be recycled with electricity to replenish its lost electrons and researchers aim to use cheap renewable sources for this in the future.

"I was pleasantly surprised when we found something as common as water could serve as the proton source; a molybdenum catalyst does not normally allow this, but ours is special," concluded Nishibayashi. "It is the first artificial nitrogen-fixing reaction to reach a rate close to that we see nitrogenase produce in nature. And like the natural process, it is passive, too, so better for the environment. I hope my life's work can be of great benefit to humanity."
-end-
Journal article

Yuya Ashida, Kazuya Arashiba, Kazunari Nakajima, Yoshiaki Nishibayashi. Molybdenum-catalyzed ammonia production with SmI2 and alcohols or water. Nature. DOI: 10.1038/s41586-019-1134-2

The present project is supported by CREST, JST (JPMJCR1541), Grants-in-Aid for Scientific Research (Nos. JP17H01201, JP15H05798 and JP18K19093) from JSPS and MEXT. Y.A. is a recipient of the JSPS Predoctoral Fellowships for Young Scientists.

Related links

Nishibayashi Laboratory
http://park.itc.u-tokyo.ac.jp/nishiba/en/

Department of Systems Innovation
http://www.sys.t.u-tokyo.ac.jp/en/

Graduate School of Engineering
https://www.t.u-tokyo.ac.jp/soee/

Previous article on this research (2017)
https://www.u-tokyo.ac.jp/focus/en/articles/a_00554.html

Research Contact

Professor Yoshiaki Nishibayashi
Department of Systems Innovation, Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, JAPAN
Tel: +81-3-5841-1175
Email: ynishiba@sys.t.u-tokyo.ac.jp

Press Contact

Mr. Rohan Mehra
Division for Strategic Public Relations, The University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, JAPAN
Tel: +81-3-5841-0876
Email: press-releases.adm@gs.mail.u-tokyo.ac.jp

About the University of Tokyo

The University of Tokyo is Japan's leading university and one of the world's top research universities. The vast research output of some 6,000 researchers is published in the world's top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 2,000 international students. Find out more at https://www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.

University of Tokyo

Related Fertilizer Articles:

Optimizing fertilizer source and rate to avoid root death
Study assembles canola root's dose-response curves for nitrogen sources.
Fertilizer feast and famine
Research led by the University of California, Davis identifies five strategies to tackle the two-sided challenge of a lack of fertilizer in some emerging market economies and inefficient use of fertilizer in developed countries.
Fertilizer plants emit 100 times more methane than reported
Emissions of methane from the industrial sector have been vastly underestimated, researchers from Cornell University and Environmental Defense Fund have found.
Where there's waste there's fertilizer
Scientists recycle phosphorus by combining dairy and water treatment leftovers.
Getting fertilizer in the right place at the right rate
In-soil placement of phosphorus can decrease phosphorus loss in snowmelt runoff
More Fertilizer News and Fertilizer Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...