Micro-texture, Stability And Macro-properties Of Fe_1-xO Modified With Foreign Element

Wustite (Fe_1-xO) is a classical example of non-stoichiometric oxides. Which is mainly applied to catalyst for ammonia synthesis in industry. There are tetrahedron and octahedron interspace formed by oxygen anion cubic closest packing. So there are structural advantage for doping and modification the Fe_1-xO. The Wtistite phase is thermodynamically stable only at temperatures above 570 ℃ , below this temperature Wtistite disappropriates into iron and magnetite. Previous research mainly focused on the properties of pure Wtistite and Wtistite based ammonia synthesis catalyst with several promoters. Micro-texture, stability and macro-properties of Fe_1-xO modified with different oxides were studied in this thesis. The effects of species and content of oxides on the properties were also investigated The major results are drawn as the folio wings:1. The study on the effects of CaO=,MgO,ZrO₂,BaO and MnO promoters on the reduction performance of Fe_1-xO were carried out. Compared to pure Wtistite, the addition of oxides decrease the reduction temperature of fastest rate (T_m) of Fe_1-xO. The addition of MgO and MnO has a slightly effect on the reduction performance of Fe_1-xO, but T_m of Fe_1-x O modified with CaO, ZrO₂ and BaO decreases significantly. The reduction activation energy calculated from DTG of Fe_1-xO modified with different oxides indicate that T_m decreases with decreasing of reduction activation energy. The reduction performance of Fe_1-xO has different changes with various oxides and their content. T_m of Fe_1-xO modified with BaO and ZrO₂ decrease with the increase of the doping content, but as doping content increase, T_m of Fe_1-xO modified with CaO,MgO and MnO present volcano-shape curve. According to the result of Mossbauer, the reduction performance of Fe_1-xO is highly dependent upon...