TiN and NbN nanoparticles were synthesized from mesoporous graphitic C3N4 (mpg-C3N4) as a reactive template and used as the catalyst for ammonia synthesis. The obtained TiN and NbN nanoparticles possess high surface areas of 299 and 275 m2 g-1, respectively, making them attractive in the use of catalysis and support. Although most of the TiN and NbN particles show no measurable activity for ammonia formation, the nanoparticles enabled an ammonia synthesis rate of 31 μmol h-1 g-cat-1 at 673 K and 0.1 MPa of synthesis gas (N2 + 3H2) for both TiN and NbN catalysts. It is evident that the formation of nanoparticles with high nitride surface area is essential for the materials to function as catalysts in ammonia synthesis. The addition of Fe to TiN enhanced the ammonia synthesis activity, whereas it had detrimental effects on the catalytic activity of NbN. The properties of these catalysts in ammonia synthesis are discussed.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work is partly supported by CREST of Japan Science and Technology Agency
(JST) named as Creation of Innovative Core Technology for Manufacture and Use of
Energy Carriers from Renewable Energy, and also partly supported by the King Abdullah
University of Science and Technology. This work is contributed to the international
exchange program Japan Society for the Promotion of Science (JSPS) named as A3
Foresight Program. The authors are grateful to N.S. Alhajri at KAUST for her
assistance in operating SEM and TEM.