【摘要】 将费-托合成铁催化剂Fe/Al₂O₃和Fe/SiO₂在空气中经一系列温度（25、120、480、650、780和1000℃）予处理并在相同条件（H₂、480℃、4h）下还原,然后作原位穆斯堡尔谱和高分辨电镜的考察,结果表明,在较低温度下予处理时,随着予处理温度的升高,Fe/Al₂O₃和Fe/SiO₂中的铁被还原为Fe（O）的量增加,但当达到某一温度（Fe/Al₂O₃为650℃、Fe/SiO₂为480℃）时出现了转折,即随着予处理温度的增加,Fe（O）%降低,意味着MSI由原来的减弱变为增强。在较低的予处理温度时,生成了难以还原的铝酸铁盐和硅酸铁盐,使MSI效应为主。适当增强MSI对提高低碳烯烃选择性有利。更多还原

【Abstract】 Fischer-Tropsch iron catalysts Fe/Al₂O₃ and Fe/SiO₂ which were pretreated in air at different temperatures （25℃,120℃,480℃,650℃, 780℃ and 1000℃） for 4h following reduction under the same conditions （H₂, 450℃, 4 h） have been studied by in-situ Mossbauer spectroscopy and highresolution electron microscopy. The results show that the percentage of Fe（0） in Fe/Al₂O₃ and Fe/SiO₂ passes through maxima at pretreatment temperatures of 650℃ and 480℃ respectively. It is ascribed to the possibility that when pretreating the samples at temperatures below the turninf points the increase in particle sizes of Fe₂O₃ which favors its reduction to iron metal, predominates over the increase in MSI for both Fe/Al₂O₃ and Fe/SiO₂, while the contrary occurs at higher pretreatment temperatures.The maximum of Fe（0）% formation （or the minimum of MSI） occurs at pretreatment temperatures of 650℃ and 480℃ for Fe/Al₂O₃ and Fe/SiO₂ respectively.MSI which is attributed to the formation of stable Fe （Ⅲ） species (Fe（Ⅲ） aluminate and Fe（Ⅲ）silicate, has been found to influence the selectivity of F-T reactions.更多还原