Preparation Of Iron Nitride By Temperature-Programmed Reaction And Catalytic Decomposition Of Hydrazine

Transition metal nitrides or carbides, such as Mo₂N and WC_x, prepared by temperature-programmed reaction (TPR) have high specific surface areas. They exhibit platinum-like catalytic characters and have been reported to be efficient for the catalytic decomposition of hydrazine. However, there are few studies on preparing iron nitrides by TPR and no study on applying them into the hydrazine decomposition. This thesis firstly focused on the synthesis of iron nitrides and their catalytic behaviors for the hydrazine decomposition. Then, nickel as a promoter was introduced in order to further improve the catalytic activity. In addition, the hydrazine decomposition over group VIII metal catalysts was also investigated. The main results are presented as follows. Nano-iron nitrides having high surface areas were formed at relatively lower nitridation temperatures from some nano-iron oxide precursors and they inherited morphologies of the oxide precursors. The iron nitride from mesoporous precursor lost the porous structure. During the TPR process, iron oxide was firstly reduced into magnetite intermediate at ca. 350℃, and then was partially nitrided into a mixture of Fe₂N and Fe3O4 as a continuing increase in temperature. When the temperature reached ca. 450℃or higher, the iron oxide was converted into Fe₂N completely. It was also found that a high space velocity of ammonia and a low heating rate were beneficial for the formation of high surface iron nitride. The structures of iron nitrides were dependent on the preparation temperature and the...