Fe1-xO基氨合成催化剂的制备化学

采用高温熔融法制备了各类铁氧化物,用XRD分析了熔融过程中的物相变化,EOS考察了熔融体凝固-冷却速率对助催化剂分布的影响.结果表明,采用大气气氛中的高温熔融法不能制取Fe₂O₃和化学计量比的FeO,前者会发生分解反应,后者会发生歧化反应;在1.333≤n(O)/n(Fe)<1.38范围时,可以制取Fe₃O₄或非化学计量比的Fe₃-yO₄;在1.113O₄和FeO的混合氧化物;在1.0451-xO,即维氏体.Fe_1-xO基催化剂的制备必须采用物理熔融与化学反应相结合的工艺.凝固冷却速度对抑制氧化亚铁的氧化反应和歧化反应,保证助催化剂的均匀分布和晶粒度均有很大影响

Preparation Chemistry of Fe1-xO Based Catalyst for Ammonia Synthesis

The preparation chemistry of iron catalyst for ammonia synthesis is studied by molten method and X-ray diffraction. The chemical reaction and the change of crystal phase of iron oxide during the molten procedure is investigated according to Fe-O equilibrium diagram. The effect of solidifying-cooling rate of molten materials on the distribution of the promoters is exposed. It is indicated that Fe 2O₃ and stoichiometric ferrous oxide FeO is not able to be obtained by molten method at atmosphere; Fe₃O₄ or non stoichiometric magnetite Fe₃-yO₄ of n (O)/ n (Fe) in the range of 1.333-1.38 and the mixture oxide of Fe₃O₄ and FeOof n (O)/ n (Fe) in the range of 1.111-1.333 may be obtained by the same method ; but non-stoichiometric ferrous oxide expressed as Fe_{1- x} O or Wustite of n (O)/ n (Fe) in the range of 1.045- 1.111 may be obtained only when the cooling rate of molten materials is more than 20 ℃/min by molten method at atmosphere. There are observable influences of the solidifying cooling rate on the inhibition of the oxidation reaction and the disproportionation of the ferrous oxide Fe_{1- x}O and improvement of the distribution of the promoters.