Fe/SiO_2纳米复合物上合成气制低碳烯烃催化性能研究

分别采用一步合成法和常规共沉淀法制备了Fe/SiO2催化剂,通过N2物理吸附、X射线衍射、透射电镜、傅里叶变换红外光谱和程序升温还原等方法对催化剂进行了表征,并在固定床反应器中对其费托合成制低碳烯烃的催化性能进行了评价。结果表明,与共沉淀铁基催化剂不同,采用一步合成法制备的纳米复合物主要由Fe3O4相构成,形貌呈规则球形,平均粒径为30 nm,尺寸分布窄,更容易还原。一步合成法制得的Fe/SiO2催化剂对费托合成反应具有较高的活性和低碳烯烃选择性、较低的甲烷选择性和良好的稳定性。

Iron-silica nanocomposites as a catalyst for the selective conversion of syngas to light olefins

A series of Fe/SiO₂ catalysts were prepared by one-pot synthesis and conventional co-precipitation methods; they were characterized by N₂ physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and temperature-programmed reduction. The performances of the Fe/SiO₂ catalysts in Fischer-Tropsch synthesis (FTS) were evaluated in a fixed-bed reactor for the production of light olefins from syngas. The results showed that in the Fe/SiO₂ catalyst prepared by one-pot synthesis method, the iron oxide is present as iron-silica nanocomposite in the form of Fe₃O₄ (magnetite). Compared with the catalyst prepared by conventional co-precipitation method, the magnetite-silica nanocomposite by one-pot synthesis exhibits a more uniform spherical-like morphology, narrower size distribution (30 nm in average) and better reducibility. In FTS, the Fe/SiO₂ catalyst prepared by one-pot synthesis method exhibits higher activity and selectivity to light olefin as well as lower selectivity to methane and better stability.