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Agglomeration Suppression of a Fe-Supported Catalyst and its Utilization for Low-Temperature Ammonia Synthesis in an Electric Field
journal contribution
posted on 2020-03-17, 08:34 authored by Ryuya Sakai, Kota Murakami, Yuta Mizutani, Yuta Tanaka, Sasuga Hayashi, Atsushi Ishikawa, Takuma Higo, Shuhei Ogo, Hideaki Tsuneki, Hiromi Nakai, Yasushi SekineFe-supported heterogeneous catalysts
are used for various reactions,
including ammonia synthesis, Fischer–Tropsch synthesis, and
exhaust gas cleaning. For the practical use of Fe-supported catalysts,
suppression of Fe particle agglomeration is the most important issue
to be resolved. As described herein, we found that Al doping in an
oxide support suppresses agglomeration of the supported Fe particle.
Experimental and computational studies revealed two tradeoff Al doping
effects: the Fe particle size decreased and remained without agglomeration
by virtue of the anchoring effect of doped Al. Also, some Fe atoms
anchored by Al cannot function as an active site because of bonding
with oxygen atoms. Using an appropriate amount of Al doping is effective
for increasing the number of active Fe sites and catalytic activity.
This optimized catalyst showed high practical activity and stability
for low-temperature ammonia synthesis in an electric field. The optimized
catalyst of 12.5 wt % Fe/Ce0.4Al0.1Zr0.5O2‑δ showed the highest ammonia synthesis
rate (2.3 mmol g–1 h–1) achieved
to date under mild conditions (464 K, 0.9 MPa) in an electric field
among the Fe catalysts reported.