skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nature of Reactive Hydrogen for Ammonia Synthesis over a Ru/C12A7 Electride Catalyst

Journal Article · · Journal of the American Chemical Society
DOI:https://doi.org/10.1021/jacs.0c02345· OSTI ID:1649278
 [1];  [2]; ORCiD logo [3];  [3]; ORCiD logo [1]; ORCiD logo [4]; ORCiD logo [3]; ORCiD logo [3];  [5];  [6]; ORCiD logo [6]; ORCiD logo [3]; ORCiD logo [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division and Center for Nanophase Materials Sciences (CNMS)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS); Clemson Univ., SC (United States). Dept. of Materials Science and Engineering
  6. Clemson Univ., SC (United States). Dept. of Materials Science and Engineering

Recently, there have been renewed interests in exploring new catalysts for ammonia synthesis under mild conditions. Electride-based catalysts are among the emerging ones. Ruthenium particles supported on an electride composed of a mixture of calcium and aluminum oxides (C12A7) have attracted great attention for ammonia synthesis due to their facile ability in activating N2 under ambient pressure. However, the exact nature of the reactive hydrogen species and the role of electride support still remain elusive for this catalytic system. Here, we report for the first time that the surface-adsorbed hydrogen, rather than the hydride encaged in the C12A7 electride, plays a major role in ammonia synthesis over the Ru/C12A7 electride catalyst with the aid of in situ neutron scattering techniques. Combining in situ neutron diffraction, inelastic neutron spectroscopy, density functional theory (DFT) calculation, and temperature-programmed reactions, the results provide direct evidence for not only the presence of encaged hydrides during ammonia synthesis but also the strong thermal and chemical stability of the hydride species in the Ru/C12A7 electride. Steady state isotopic transient kinetic analysis (SSITKA) of ammonia synthesis showed that the coverage of reactive intermediates increased significantly when the Ru particles were promoted by the electride form (coverage up to 84%) of the C12A7 support rather than the oxide form (coverage up to 15%). Such a drastic change in the intermediate coverage on the Ru surface is attributed to the positive role of electride support where the H2 poisoning effect is absent during ammonia synthesis over Ru. The finding of this work has significant implications for understanding catalysis by electride-based materials for ammonia synthesis and hydrogenation reactions in general.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Organization:
USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC)
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231
OSTI ID:
1649278
Journal Information:
Journal of the American Chemical Society, Vol. 142, Issue 16; ISSN 0002-7863
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 40 works
Citation information provided by
Web of Science

References (64)

How a century of ammonia synthesis changed the world journal September 2008
Ammonia as a feedstock for a hydrogen fuel cell; reformer and fuel cell behaviour journal April 1994
Ammonia as a green fuel and hydrogen source for vehicular applications journal May 2009
Ammonia for hydrogen storage: challenges and opportunities journal January 2008
Surface, catalytic and magnetic properties of small iron particles II. Structure sensitivity of ammonia synthesis journal June 1975
The importance of C7 sites and surface roughness in the ammonia synthesis reaction over iron journal January 1987
Primary steps in catalytic synthesis of ammonia journal April 1983
Kinetics and Mechanism of Ammonia Synthesis journal January 1981
Ruthenium Nanocatalysts for Ammonia Synthesis: A Review journal October 2014
Role of alkali promoter in ammonia synthesis over ruthenium catalysts—Effect on reaction mechanism journal May 2017
Role of Steps in N 2 Activation on Ru(0001) journal August 1999
Dissociative adsorption of N on ru(0001): A surface reaction totally dominated by steps journal June 2000
Structure sensitivity of supported ruthenium catalysts for ammonia synthesis journal December 2000
Ruthenium catalysts for ammonia synthesis at high pressures: Preparation, characterization, and power-law kinetics journal April 1997
Surface science based microkinetic analysis of ammonia synthesis over ruthenium catalysts journal June 2000
The microkinetics of ammonia synthesis catalyzed by cesium-promoted supported ruthenium journal May 1996
High-Density Electron Anions in a Nanoporous Single Crystal: [Ca24Al28O64]4+(4e-) journal August 2003
Ammonia synthesis using a stable electride as an electron donor and reversible hydrogen store journal October 2012
Ru-Loaded C12A7:e Electride as a Catalyst for Ammonia Synthesis journal February 2017
Electride support boosts nitrogen dissociation over ruthenium catalyst and shifts the bottleneck in ammonia synthesis journal March 2015
Water Durable Electride Y 5 Si 3 : Electronic Structure and Catalytic Activity for Ammonia Synthesis journal March 2016
Tiered Electron Anions in Multiple Voids of LaScSi and Their Applications to Ammonia Synthesis journal July 2017
High Electron Density on Ru in Intermetallic YRu 2 : The Application to Catalyst for Ammonia Synthesis journal April 2018
Essential role of hydride ion in ruthenium-based ammonia synthesis catalysts journal January 2016
Metal-Dependent Support Effects of Oxyhydride-Supported Ru, Fe, Co Catalysts for Ammonia Synthesis journal November 2018
Hydrides, Amides and Imides Mediated Ammonia Synthesis and Decomposition journal March 2019
Recent progress towards mild-condition ammonia synthesis journal September 2019
Breaking scaling relations to achieve low-temperature ammonia synthesis through LiH-mediated nitrogen transfer and hydrogenation journal August 2016
Alkali and Alkaline Earth Hydrides-Driven N 2 Activation and Transformation over Mn Nitride Catalyst journal October 2018
Kinetic evidence: the rate-determining step for ammonia synthesis over electride-supported Ru catalysts is no longer the nitrogen dissociation step journal January 2017
Simple and Efficient Fabrication of Mayenite Electrides from a Solution-Derived Precursor journal September 2017
Facile and Massive Aluminothermic Synthesis of Mayenite Electrides from Cost-Effective Oxide and Metal Precursors journal December 2018
Measurement of ruthenium metal surface area by chemisorption journal July 1974
The Nanoscale Ordered MAterials Diffractometer NOMAD at the Spallation Neutron Source SNS
  • Neuefeind, Jörg; Feygenson, Mikhail; Carruth, John
  • Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Vol. 287 https://doi.org/10.1016/j.nimb.2012.05.037
journal September 2012
GSAS-II : the genesis of a modern open-source all purpose crystallography software package journal March 2013
VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data journal October 2011
Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set journal October 1996
Generalized Gradient Approximation Made Simple journal October 1996
Projector augmented-wave method journal December 1994
From ultrasoft pseudopotentials to the projector augmented-wave method journal January 1999
Role of hydrogen atoms in the photoinduced formation of stable electron centers in H-doped 12 CaO 7 Al 2 O 3 journal January 2006
A climbing image nudged elastic band method for finding saddle points and minimum energy paths journal December 2000
Simulation of Inelastic Neutron Scattering Spectra Using OCLIMAX journal January 2019
Elucidation of the Reaction Mechanism for High-Temperature Water Gas Shift over an Industrial-Type Copper–Chromium–Iron Oxide Catalyst journal April 2019
Isotopic Transient Kinetic Analysis of Cs-Promoted Ru/MgO during Ammonia Synthesis journal September 2002
Isotopic transient analysis of ammonia synthesis over Ru/MgO catalysts promoted by cesium, barium, or lanthanum journal March 2004
Iodometric Determination of Electrons Incorporated into Cages in 12CaO·7Al 2 O 3 Crystals journal August 2010
Mechanism Switching of Ammonia Synthesis Over Ru-Loaded Electride Catalyst at Metal–Insulator Transition journal November 2015
Alkali Promotion of N 2 Dissociation over Ru(0001) journal May 1998
Promoter action of alkali nitrate in Raney ruthenium catalyst for activation of dinitrogen journal November 1991
Nature of nitrogen adsorbed on transition metal surfaces as revealed by electron spectroscopy and cognate techniques journal January 1991
The effects of potassium on ammonia synthesis over iron single-crystal surfaces journal January 1988
Electronic factors in catalysis: the volcano curve and the effect of promotion in catalytic ammonia synthesis journal December 2001
Ammonia synthesis over a Ru(0001) surface studied by density functional calculations journal December 2003
Structure and Electrons in Mayenite Electrides journal April 2008
Hydride ions in oxide hosts hidden by hydroxide ions journal March 2014
Introduction to the Characterization of Residual Stress by Neutron Diffraction book January 2005
Neutron Scattering Investigations of Hydride Species in Heterogeneous Catalysis journal November 2018
Neutron spectroscopy as a tool in catalytic science journal January 2017
Hydride Ion as a Two-Electron Donor in a Nanoporous Crystalline Semiconductor 12CaO·7Al 2 O 3 journal December 2005
CHEMISTRY: Chemical Reactions Involving Quantum Tunneling journal February 2003
Experimental Demonstration of an Electride as a 2D Material journal November 2016
Electrons on the surface of 2D materials: from layered electrides to 2D electrenes journal January 2017
Self-organized Ruthenium-Barium Core-Shell Nanoparticles on a Mesoporous Calcium Amide Matrix for Efficient Low-Temperature Ammonia Synthesis journal February 2018