A Density Functional Theory Modeling Investigation into the Reaction Mechanisms of Ammonia Reduction of Iron Oxide Represented by the Fe2O3 (001) Surface

The reaction mechanisms of NH 3 reduction of Fe 2 O 3, represented by the Fe 2 O 3 (001) surface with a low surface hydrogen coverage, have been studied through density functional theory (DFT) simulation. Various reaction mechanisms are first hypothesized, and then the energy barriers of each of the proposed mechanisms are calculated to determine the most probable reaction pathway. The most likely pathway for NH 3 reduction of Fe 2 O 3 to form H 2 O involves successive abstraction of H atoms from NH 3 adsorbed on the Fe site, which combine with an O in Fe 2 O 3 (001) to form hydroxyl groups, while the H atom in remaining NH reacts with the OH to form H 2 O. NH 3 dissociation to H 2 involves the H atom from the remaining NH reacting with the H atom abstracted from NH 3 and adsorbed on the O atom adjacent to the Fe site (H ad ) to form H 2 . The N atom adsorbed on the Fe site can also react with the O atom adjacent to the Fe site to form NO. On the Fe 2 O 3 (001) surface, the NH 3 reduction of Fe 2 O 3 directly plays a dominant role in the reduction process due to the lower energy barrier.