摘要
本文应用穆斯堡尔谱方法,研究了以沉淀法制备的Fe-Eu系F-T催化剂在焙烧、还原、碳化及催化反应后铁的化学形态的变化和助剂Eu对Fe的化学调变作用.结果表明,Eu与Fe存在较强的相互作用,从而稳定了铁晶粒,促进催化剂的还原,并对碳化有延滞作用.Eu_2O_3为铁的优良结构和化学助催化剂.
Mossbauer spectroscopy was used to study the chemical state of precipitated Fe and Fe- Eu catalysts under different stages of calcination, reduction, carburization and reaction. The effect of Eu2O3 promotor is related to the structural and chemical modification of the iron catalyst.
After calcination at 350, 500 and 700℃, it can be seen that the addition of Eu2O3 promotor to the Fe catalyst increases the dispersion and stability of iron, and causes a significant decrease of Fe2O3 partical sizes. After reduction of the iron phase in hydrogen at 280℃, the Fe catalyst is completely changed to Fe2O3, and the Fe-Eu catalyst contains about 41% of α-Fe and 5% of Fe3O4 after reduction. The Eu2O3 promotor improves the reduction of the iron catalyst. Fe-Eu catalyst consists of the Eu ions strongly interacting with the Fe ions. When the reduced Fe and Fe-Eu catalyst were carburized at 250℃ in synthesis gas (H2/CO=2) , the iron phase completely converted to stable Hagg's carbide χ-Fe5C2. Direct carburization of the unreduced Fe and Fe-Eu catalysts leads to the formation of bulk phase χ- Fe5C2 and Fe3O4. Addition of Eu2O3 retards the carburization of iron catalyst.
Some evidences for Fe-Eu redox interaction and Mossbaur hyperfine parameter were obtained.
出处
《分子催化》
EI
CAS
CSCD
1993年第3期186-192,共7页
Journal of Molecular Catalysis(China)
基金
国家自然科学基金资助项目
关键词
铁
铕
催化剂
F-T合成
穆斯堡尔谱
Fe-Eu catalyst, F-T synthesis, Mossbauer spectroscopy.
