An energy-efficiency lead for nitrogen fertilizer production

Nitrogen and phosphorus fertilizers are essential in modern agriculture and crucial to meeting the ever-growing global food demand. Nitrogen fertilizer, in the form of ammonia, is produced now in the same way that it has been for close to a…

Nitrogen and phosphorus fertilizers are essential in modern agriculture and crucial to meeting the ever-growing global food demand. Nitrogen fertilizer, in the form of ammonia, is produced now in the same way that it has been for close to a century—by the energy-intensive Haber-Bosch process, which uses high temperatures and pressures to split nitrogen gas molecules. Takanori Shima, Zhaomin Hou and colleagues from the RIKEN Center for Sustainable Resource Science have now made a discovery that could allow ammonia and other nitrogen-bearing compounds to be produced energy-efficiently at room temperature.

Nitrogen gas (N2), comprised of a pair of nitrogen atoms, is abundant in the atmosphere, but converting it to a useful solid form by breaking the triple bond between the nitrogen atoms consumes considerable energy. Chemists have had difficulty finding ways to break the triple bond at mild temperatures without resorting to special electron- and proton-donating reagents, which are generally nonrecyclable and expensive.
Hou and his colleagues instead considered multinuclear transition metal hydrides—cage-like compounds in which several metals are linked together by multiply bonded hydrogen atoms. These hydrides can generate sufficient electrons to break the triple bond and also act as a hydrogen source for the fixation of nitrogen as ammonia. The team also suspected that the metal centers could enhance N2 activation through cooperative effects seen in biological nitrogen fixation and the Haber-Bosch process.
Drawing on their expertise in rare-earth hydrides, the researchers produced a novel complex based on titanium—a transition metal that readily forms nitrogen bonds. Their experiments involved mixing the titanium precursor with hydrogen gas and N2 in a pressure reactor at room temperature. Rather than the pure metal hydride they expected, the reaction produced a strained cubic structure containing four bridged titanium hydrides and, intriguingly, a pair of nitrogen–proton (N–H) units.
To understand how this complex formed, the team went back and monitored each step of the reaction using x-ray crystallography and isotope-labeled spectroscopy. They determined that N2 was activated and cleaved by binding simultaneously to three titanium atoms, and that the hydrides migrated from titanium to the nitrogen portion of the complex. “This is unprecedented, to observe N2 activation, bond cleavage and N–H bond formation steps in one reaction,” says Shima.
Although the researchers are still investigating why the trinuclear titanium complex has such particular affinity for N2 compounds, they are certain that these materials will provide a unique opportunity to develop innovative nitrogen fixation strategies.

Explore further:

When boron butts in: Bridging N–N ligand borylation in group 4 metallocene complexes

More information: Shima, T., et al. Dinitrogen cleavage and hydrogenation by a trinuclear titanium polyhydride complex, Science 340, 1549–1552 (2013). dx.doi.org/10.1126/science.1238663

Journal reference:

Science

Provided by

RIKEN

view popular

5 /5 (1 vote)

Related Stories

When boron butts in: Bridging N–N ligand borylation in group 4 metallocene complexes

Apr 05, 2013

For nature and chemists alike, making atmospheric nitrogen available for the formation of more complex nitrogen compounds is both essential and difficult. In the European Journal of Inorganic Chemistry, Paul C …

Direct nitrogen fixation for low cost energy conversion

Jul 23, 2013

A simple, low-cost and eco-friendly method of creating nitrogen-doped graphene nanoplatelets (NGnPs), which could be used in dye-sensitized solar cells and fuel cells, is published in Scientific Reports today. …

Converting Nitrogen to a More Useful Form

Jan 09, 2007

Nitrogen-containing organic compounds are important products as well as intermediates for many pharmaceuticals, agrochemicals, and chemicals used in electronics. Air contains plenty of nitrogen, but it is in a form that cannot …

New way to break some of the strongest chemical bonds

Dec 16, 2009

(PhysOrg.com) — Scientists at Cornell University in the U.S. have found a new way of breaking two of the strongest chemical bonds, at ambient temperature and pressure, and this breakthrough could lead to …

High rates of nitrogen fixation measured in equatorial upwelling region

Apr 05, 2013

Surface waters in upwelling regions of the ocean are generally rich in nutrients. Scientists had thought that these areas would have low rates of nitrogen fixation because diazotrophs-microbes that convert nitrogen gas from …

Study suggests second life for possible spintronic materials

Jun 06, 2013

Ten years ago, scientists were convinced that a combination of manganese and gallium nitride could be a key material to create spintronics, the next generation of electronic devices that operate on properties …

Recommended for you

A durable, bacteria-killing surface for hospitals

6 hours ago

Scientists at EPFL have developed a new method for making antimicrobial surfaces that can eliminate bacteria under a minute. The technology, now tested in a hospital, shows enormous potential for preventing …

Chemists devise new way to prepare molecules for drug testing

Aug 15, 2013

(Phys.org) —James Bond had his reasons for ordering his martinis “shaken, not stirred.” Similarly, drug manufacturers need to make sure the molecules in a new drug are arranged in an exact manner, lest …

Beetles in rubber boots: Scientists study ladybirds’ feet

Aug 15, 2013

During their evolution, insects have developed various unique features to survive in their environment. The knowledge of the working principles of insects’ microstructures holds great potential for the development …

A new sense of urgency for energy cane and other energy crops

Aug 14, 2013

“Energy cane” may sound like a trendy sports drink, but it actually is among a new generation of energy crops that could yield up to 5 times more ethanol per acre than corn. They are the topic of the cover story in this week’s …

Explosive nanotechnology: Highly reactive nanoenergetic formulations based on periodate salts

Aug 14, 2013

(Phys.org) —Whether they are rocket propellants or fireworks, all explosives contain a fuel and an oxidizing agent. Sometimes both are in the same molecule, like in TNT; sometimes the explosive is a mixture, …

One-pot to prep biomass for biofuels

Aug 14, 2013

(Phys.org) —The advantages of the “one-stop” shop have long been recognized in the retailing and services industries. Similar advantages would also be realized for the biofuels industry with the development …

User comments : 0

More news stories

How DNA repair helps prevent cancer

The biological information that makes us unique is encoded in our DNA. DNA damage is a natural biological occurrence that happens every time cells divide and multiply. External factors such as overexposure …

New prototype device recognizes electrical properties of infected cells as signatures of disease

Researchers at MIT have found a way to detect early-stage malarial infection of blood cells by measuring changes in the infected cells’ electrical properties.

Deadly folding mistake: Molecular mechanism of prion protein oligomerization at atomic resolution

(Phys.org) —Mad cow disease and its cousin Creutzfeld-Jakob disease cause fatal spongy changes in brain tissue. Today, we know that these diseases are caused by prions, proteins that are folded incorrectly. …

A durable, bacteria-killing surface for hospitals

Scientists at EPFL have developed a new method for making antimicrobial surfaces that can eliminate bacteria under a minute. The technology, now tested in a hospital, shows enormous potential for preventing …

Upsalite: Scientists make ‘impossible material’… by accident

Researchers in Uppsala, Sweden accidentally left a reaction running over the weekend and ended up resolving a century-old chemistry problem. Their work has led to the development of a new material, dubbed …

Severe hypoglycemia in diabetes tied to cardiac disease

(HealthDay)—For patients with type 1 and type 2 diabetes, severe hypoglycemia is associated with severe hypertension, hypokalemia, and QT prolongation, according to a study published online Aug. 12 in Diabetes Ca …

Breath and butter: Resolving cholesterol’s role in human lung surfactants

(Medical Xpress)—Pulmonary surfactants are phospholipoproteins (surface-active lipoprotein complexes) that reduces alveolar surface tension through an air-water hydrophilic/hydrophobic interface. Pulmonary, …

‘Listening’ to black holes form with gravity waves

New technology that breaks the quantum measurement barrier has been developed to detect the gravity waves first predicted by Einstein in 1916.

New research suggests perovskite as cheaper replacement for silicon-based solar panels

(Phys.org) —Researchers at Oxford Photovoltaics and other companies investigating the use of perovskite—a crystalline organometal—as a replacement for silicon in photovoltaic cells have created prototypes …

Microsoft India team develop secure Peer-to-Peer acoustic NFC system

(Phys.org) —A team of researchers at Microsoft India has developed an alternative to standard NFC communications between hand-held devices—a software only system that makes use of the speaker and microphone …