Skip to main content
  • Submit
  • About
    • Editorial Board
    • PNAS Staff
    • FAQ
    • Accessibility Statement
    • Rights and Permissions
    • Site Map
  • Contact
  • Journal Club
  • Subscribe
    • Subscription Rates
    • Subscriptions FAQ
    • Open Access
    • Recommend PNAS to Your Librarian
  • Log in
  • My Cart

Main menu

  • Home
  • Articles
    • Current
    • Special Feature Articles - Most Recent
    • Special Features
    • Colloquia
    • Collected Articles
    • PNAS Classics
    • List of Issues
  • Front Matter
  • News
    • For the Press
    • This Week In PNAS
    • PNAS in the News
  • Podcasts
  • Authors
    • Information for Authors
    • Editorial and Journal Policies
    • Submission Procedures
    • Fees and Licenses
  • Submit
  • About
    • Editorial Board
    • PNAS Staff
    • FAQ
    • Accessibility Statement
    • Rights and Permissions
    • Site Map
  • Contact
  • Journal Club
  • Subscribe
    • Subscription Rates
    • Subscriptions FAQ
    • Open Access
    • Recommend PNAS to Your Librarian

User menu

  • Log in
  • My Cart

Search

  • Advanced search
Home
Home

Advanced Search

  • Home
  • Articles
    • Current
    • Special Feature Articles - Most Recent
    • Special Features
    • Colloquia
    • Collected Articles
    • PNAS Classics
    • List of Issues
  • Front Matter
  • News
    • For the Press
    • This Week In PNAS
    • PNAS in the News
  • Podcasts
  • Authors
    • Information for Authors
    • Editorial and Journal Policies
    • Submission Procedures
    • Fees and Licenses

New Research In

Physical Sciences

Featured Portals

  • Physics
  • Chemistry
  • Sustainability Science

Articles by Topic

  • Applied Mathematics
  • Applied Physical Sciences
  • Astronomy
  • Computer Sciences
  • Earth, Atmospheric, and Planetary Sciences
  • Engineering
  • Environmental Sciences
  • Mathematics
  • Statistics

Social Sciences

Featured Portals

  • Anthropology
  • Sustainability Science

Articles by Topic

  • Economic Sciences
  • Environmental Sciences
  • Political Sciences
  • Psychological and Cognitive Sciences
  • Social Sciences

Biological Sciences

Featured Portals

  • Sustainability Science

Articles by Topic

  • Agricultural Sciences
  • Anthropology
  • Applied Biological Sciences
  • Biochemistry
  • Biophysics and Computational Biology
  • Cell Biology
  • Developmental Biology
  • Ecology
  • Environmental Sciences
  • Evolution
  • Genetics
  • Immunology and Inflammation
  • Medical Sciences
  • Microbiology
  • Neuroscience
  • Pharmacology
  • Physiology
  • Plant Biology
  • Population Biology
  • Psychological and Cognitive Sciences
  • Sustainability Science
  • Systems Biology
QnAs

QnAs with Helmut Schwarz

Farooq Ahmed
PNAS November 13, 2018 115 (46) 11657-11658; first published October 22, 2018; https://doi.org/10.1073/pnas.1816806115
Farooq Ahmed
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site

See related content:

  • Ta2+-mediated ammonia synthesis from N2 and H2 at ambient temperature
    - Oct 23, 2018
  • Article
  • Figures & SI
  • Info & Metrics
  • PDF
Loading

In the early 1900s, German chemists Fritz Haber and Carl Bosch developed a way to synthesize ammonia from atmospheric nitrogen and methane-derived hydrogen. The method became a vital step in manufacturing not only fertilizers but also explosives. Haber likened the process to making “bread from air” (Haber and Bosch are both winners of Nobel Prizes in Chemistry). In his Inaugural Article (1), the chemist Helmut Schwarz has himself devised a method to “make bread from air,” synthesizing ammonia from nitrogen and hydrogen using the metal tantalum as a catalyst. A professor of chemistry at the Technische Universität Berlin, Schwarz has uncovered the mechanisms of catalysis at an atomic level. He has identified so-called “aristocratic atoms,” which act as the workhorses of chemical reactions and has deepened our understanding of organometallic processes. Schwarz has also served as President of the Alexander von Humboldt Foundation, which supports international partnerships between scientists from Germany and around the world. PNAS recently spoke to Schwarz, who was elected as a Foreign Associate of the National Academy of Sciences in 2018, about his current research.

Figure1
  • Download figure
  • Open in new tab
  • Download powerpoint

Helmut Schwarz. Image courtesy of the Alexander von Humboldt Foundation/David Ausserhofer.

PNAS:In your Inaugural Article (1), you replicate the Haber–Bosch process. What does your method demonstrate?

Schwarz:About 1% of energy consumption on Earth goes into making ammonia, because the process is extremely energy-demanding and the product is used in so many ways. The challenge in ammonia synthesis is breaking the triple bond in atmospheric nitrogen so that it will accept hydrogen atoms. I have been looking at the Haber–Bosch process for several years now. It relies on high temperature and high pressure to activate the hydrogen molecule and to cleave the nitrogen triple bond.

Our experiment may not be more energy efficient, but it is a new attempt at an entrenched problem. We combined experimental and computational methods to understand how to form ammonia at ambient temperature, in the gas phase. The benefit is that in the gas phase we have removed complicating factors that exist with reactions in condensed phases. Our approach has enabled us to identify the elementary steps and the structure of reaction intermediates, both in the activation of nitrogen and in the decomposition of ammonia, at a strictly atomistic level.

The widely available transition metal tantalum acts as a diatomic cluster and breaks the dinitrogen triple bond to form a four-membered ring structure of alternating tantalum and nitrogen atoms. Only tantalum does this type of chemistry at ambient temperature in the gas phase. In the forward reaction, the catalyst serves as both an electron acceptor and donor during the cleavage of dinitrogen, and also splits the dihydrogen single bond. We find the very same intermediate in the reverse reaction. We hope that [our method] might improve the ammonia synthesis process and in the future help conserve ecological resources.

PNAS:How does this work fit within the broader context of your research?

Schwarz:For at least the past 20 years, I have been interested in activating small, inert molecules like nitrogen, methane, and carbon dioxide at ambient temperatures to provide an understanding of how they can react. For example, the oxidation of methane to methanol is a huge challenge —a sort of a “Holy Grail”—and the mechanism was an ongoing controversy for decades among biochemists. By paring it all down to just the few atoms at the active centers of the molecules, we learned with electronic structure calculations that various types of reactions can take place. We developed a new concept, looking at the role of spin states, which is now broadly accepted (2, 3).

The commonality of these various problems is identifying pathways that are only accessible by using particular transition metal elements as catalysts.

Gas-phase experiments, however, do not lend themselves to upscaling; they exclude everything which matters in real life. However, as we’ve shown from our work, a mechanistic understanding can provide suggestions for improving existing technologies. In this process, hydrogen cyanide is synthesized from methane and ammonia at 1,500 Kelvin with a platinum catalyst (4).

When we first started combining a theoretical/computational approach with an experimental one in the 1980s, we were criticized. At that time, computational chemistry was not where it is today, and using it was more the exception than the rule. It’s very standard now, and we use theory to guide our experiments. The computational side really has opened the doors to test reactions that were unthinkable years ago.

PNAS:How did you decide to focus on computational chemistry, and where do you see your work headed in the future?

Schwarz:Back before I went to university, I wasn’t sure what to study. I was interested in physics and chemistry, but also law and theater. I am extremely fortunate to do research in Germany where by and large there is sufficient funding for sometimes seemingly “useless studies.” I could pick problems to look at from the standpoint of curiosity and not utility or “what good does this do for society?” (5).

I’m still interested in some very basic questions in chemistry, like: How do you transition from a small system of molecules to a larger system? How many molecules does it take to make a solution and to see the effects of the solution on the chemistry of a reaction? What difference do minor electric fields play at the active center of a small catalyst on a molecular level?

Personally, I value the so-called “usefulness of useless knowledge” (5), which was a phrase coined by Abraham Flexner, who founded the Institute for Advanced Study at Princeton. As long ago as 1939, he argued against a need for utility in promoting research and allocating funding. It is a cause I remain dedicated to today.

Footnotes

    • This is a QnAs with a member of the National Academy of Sciences to accompany the member’s Inaugural Article on page 11680.

    Published under the PNAS license.

    References

    1. ↵
      1. Geng C,
      2. Li J,
      3. Weiske T,
      4. Schwarz H
      (2018) Ta2+-mediated ammonia synthesis from N2 and H2 at ambient temperature. Proc Natl Acad Sci USA 115:11680–11687.
      OpenUrlAbstract/FREE Full Text
    2. ↵
      1. Schwarz H
      (2014) How and why do cluster size, charge state, and ligands affect the course of metal-mediated gas-phase activation of methane? Isr J Chem 54:1413–1431.
      OpenUrl
    3. ↵
      1. Schröder D,
      2. Shaik S,
      3. Schwarz H
      (2000) Two-state reactivity as a new concept in organometallic chemistry. Acc Chem Res 33:139–145.
      OpenUrlPubMed
    4. ↵
      1. Diefenbach M,
      2. Brönstrup M,
      3. Aschi M,
      4. Schröder D,
      5. Schwarz H.
      (1999) HCN synthesis from methane and ammonia: Mechanism of PT+-mediated C–N coupling. J Am Chem Soc 121:10614–10625.
      OpenUrl
    5. ↵
      1. Schwarz H
      (2017) On the usefulness of useless knowledge. Nat Rev Chem 1:0001.
      OpenUrl
    PreviousNext
    Back to top
    Article Alerts
    Email Article

    Thank you for your interest in spreading the word on PNAS.

    NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

    Enter multiple addresses on separate lines or separate them with commas.
    QnAs with Helmut Schwarz
    (Your Name) has sent you a message from PNAS
    (Your Name) thought you would like to see the PNAS web site.
    CAPTCHA
    This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
    Citation Tools
    QnAs with Helmut Schwarz
    Farooq Ahmed
    Proceedings of the National Academy of Sciences Nov 2018, 115 (46) 11657-11658; DOI: 10.1073/pnas.1816806115

    Citation Manager Formats

    • BibTeX
    • Bookends
    • EasyBib
    • EndNote (tagged)
    • EndNote 8 (xml)
    • Medlars
    • Mendeley
    • Papers
    • RefWorks Tagged
    • Ref Manager
    • RIS
    • Zotero
    Request Permissions
    Share
    QnAs with Helmut Schwarz
    Farooq Ahmed
    Proceedings of the National Academy of Sciences Nov 2018, 115 (46) 11657-11658; DOI: 10.1073/pnas.1816806115
    Digg logo Reddit logo Twitter logo Facebook logo Google logo Mendeley logo
    • Tweet Widget
    • Facebook Like
    • Mendeley logo Mendeley
    Proceedings of the National Academy of Sciences: 115 (46)
    Table of Contents

    Submit

    Sign up for Article Alerts

    Jump to section

    • Article
      • Footnotes
      • References
    • Figures & SI
    • Info & Metrics
    • PDF

    You May Also be Interested in

    Surgeons hands during surgery
    Inner Workings: Advances in infectious disease treatment promise to expand the pool of donor organs
    Despite myriad challenges, clinicians see room for progress.
    Image credit: Shutterstock/David Tadevosian.
    Setting sun over a sun-baked dirt landscape
    Core Concept: Popular integrated assessment climate policy models have key caveats
    Better explicating the strengths and shortcomings of these models will help refine projections and improve transparency in the years ahead.
    Image credit: Witsawat.S.
    Double helix
    Journal Club: Noncoding DNA shown to underlie function, cause limb malformations
    Using CRISPR, researchers showed that a region some used to label “junk DNA” has a major role in a rare genetic disorder.
    Image credit: Nathan Devery.
    Steamboat Geyser eruption.
    Eruption of Steamboat Geyser
    Mara Reed and Michael Manga explore why Yellowstone's Steamboat Geyser resumed erupting in 2018.
    Listen
    Past PodcastsSubscribe
    Birds nestling on tree branches
    Parent–offspring conflict in songbird fledging
    Some songbird parents might improve their own fitness by manipulating their offspring into leaving the nest early, at the cost of fledgling survival, a study finds.
    Image credit: Gil Eckrich (photographer).

    Similar Articles

    Site Logo
    Powered by HighWire
    • Submit Manuscript
    • Twitter
    • Facebook
    • RSS Feeds
    • Email Alerts

    Articles

    • Current Issue
    • Special Feature Articles – Most Recent
    • List of Issues

    PNAS Portals

    • Anthropology
    • Chemistry
    • Classics
    • Front Matter
    • Physics
    • Sustainability Science
    • Teaching Resources

    Information

    • Authors
    • Editorial Board
    • Reviewers
    • Librarians
    • Press
    • Site Map
    • PNAS Updates

    Feedback    Privacy/Legal

    Copyright © 2021 National Academy of Sciences. Online ISSN 1091-6490