Cation doped cerium oxynitride with anion vacancies for Fe-based catalyst with improved activity and oxygenate tolerance for efficient synthesis of ammonia

John Humphreys, Rong Lan, Shigang Chen, Marc Walker, Yisong Han, Shanwen Tao

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)
44 Downloads (Pure)

Abstract

For the first time, new Sm doped cerium oxynitrides with the formula Ce 1-zSm zO 2-xN y (z ≤ 0.5) are synthesized in order to maximize the concentration of anion vacancies. Single phase Sm-doped CeO 2-xN y were confirmed by XRD, HRTEM and Rietveld refinement. These oxynitrides show a great promotion effect for the low-cost Fe catalyst for the ammonia synthesis. At 350 °C and 1 MPa, the activity of 80 wt% Fe- 20 wt% Ce 1-zSm zO 2xN y is one of the highest reported for non-Ru catalysts for the Haber-Bosch reaction. The apparent activation energy of the 80 wt% Fe- 20 wt% Ce 1-zSm zO 2xN y catalysts with z ≥ 0.3 is around 45 kJ/mol, which is in the lowest range among all reported ammonia synthesis catalysts. Introduction of nitrogen vacancies through doping may facilitate the mobility of nitrogen vacancies. This study demonstrates doped oxynitrides with a large concentration of anion vacancies, particularly nitrogen vacancies are excellent promoters/co-catalysts for ammonia synthesis.

Original languageEnglish
Article number119843
Number of pages15
JournalApplied Catalysis B: Environmental
Volume285
Early online date25 Dec 2020
DOIs
Publication statusPublished - 15 May 2021
Externally publishedYes

Bibliographical note

This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/4.0/),
which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited..

Funder

EPSRC (Grant No. EP/G01244X/1

Keywords

  • Oxynitride
  • Nitrogen vacancy
  • Ammonia synthesis
  • Oxygenate
  • Activation energy

ASJC Scopus subject areas

  • Environmental Science(all)
  • Process Chemistry and Technology
  • Catalysis

Fingerprint

Dive into the research topics of 'Cation doped cerium oxynitride with anion vacancies for Fe-based catalyst with improved activity and oxygenate tolerance for efficient synthesis of ammonia'. Together they form a unique fingerprint.

Cite this