Mechanism of NH 3 synthesis over hexagonal Ca 3 CrN 3 H Yoji Kobayashi 1 , Yu Cao 1 , Ekaterina Toshcheva 2 , Walid Almaksoud 2 , Rafia Ahmad 2 , Rohit Rai 2 , Tatsuya Tsumori 1 , Ya Tang 3 , Luigi Cavallo 2 and Hiroshi Kageyama 1 1 Kyoto University, Japan, 2 King Abdullah University of Science and Technology, Saudi Arabia 3 Shanghai University, China 3 synthesis under Haber- Bosch conditions. We will present our kinetic/isotope studies, and results from DFT calculations which suggest an associative mechanism for NH 3 synthesis where the active sites consist of Ca 3 centers and a distant Cr atom. These results are unusual in light of most classic catalysts where activity is well-predicted by the volcano plot, placing Fe, Ru, and Co as most active. Even when compared to recent research concerning hydrides and early (transition) metals as catalysts [2,3], the direct interaction of Ca has not been reported as far, and our highly crystalline material permits extensive structural studies. We propose the readily available channels of mobile 1-D hydride channels near the active site take an important part in the N 2 activation step. References We find that a newly discovered nitride-hydride Ca 3 CrN 3 H 1 is an active catalyst for NH 1. Cao, Y.; Kirsanova, M. A.; Ochi, M.; Al Maksoud, W.; Zhu, T.; Rai, R.; Gao, S.; Tsumori, T.; Kobayashi, S.; Kawaguchi, S.; Abou-Hamad, E.; Kuroki, K.; Tassel, C.; Abakumov, A. M.; Kobayashi, Y.; Kageyama, H. Topochemical Synthesis of Ca 3 CrN 3 H Involving a Rotational Structural Transformation for Catalytic Ammonia Synthesis. Angew. Chem. Int. Ed. 2022 , 61, e202209187. 2. Wang, P.; Chang, F.; Gao, W.; Guo, J.; Wu, G.; He, T.; Chen, P. Breaking scaling relations to achieve low-temperature ammonia synthesis through LiH-mediated nitrogen transfer and hydrogenation. Nat. Chem. 2017 , 9, 64–70. 3. Guan, Y.; Zhang, W.; Wang, Q.; Weidenthaler, C.; Wu, A.; Gao, W.; Pei, Q.; Yan, H.; Cui, J.; Wu, H.; Feng, S.; Wang, R.; Cao, H.; Ju, X.; Liu, L.; He, T.; Guo, J.; Chen, P. Barium chromium nitride-hydride for ammonia synthesis. Chem Catal. 2021 , 1, 1042–1054.
P30
© The Author(s), 2023
Made with FlippingBook Learn more on our blog