摘要
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 Fe2 O3和化学计量比的 Fe O,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- y O4;在 1 .1 1 <n( O) /n( Fe) <1 .333范围时 ,可以制取 Fe3O4和 Fe O的混合氧化物 ;在 1 .0 4 5 <n( O) /n( Fe) <1 .1 1 1范围 ,平均冷却速度大于 2 0℃ /min时 ,可以制取非化学计量比的氧化亚铁 Fe1 - x O,即维氏体 .Fe1 - x O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 。
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 2O 3 and stoichiometric ferrous oxide FeO is not able to be obtained by molten method at atmosphere; Fe 3O 4 or non stoichiometric magnetite Fe 3 y O 4 of n (O)/ n (Fe) in the range of 1.333-1.38 and the mixture oxide of Fe 3O 4 and FeO of 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.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2002年第1期87-91,共5页
Chemical Journal of Chinese Universities
基金
国家自然科学基金 (批准号 :2 970 6 0 11)
国家九五攻关项目 (批准号 :96 -5 5 0 -0 2 -0 1)资助 .
关键词
氨合成催化剂
制备化学
熔融法
铁氧化物
Ammonia synthesis catalyst
Fe 1- x O
Preparation chemistry
Molten method
