Microfibrous-structured Al-fiber@ns-Al2O3 core–shell composite functionalized by Fe–Mn–K via surface impregnation combustion: as-burnt catalysts for synthesis of light olefins from syngas
Microfibrous-structured Al-fiber@ns-Al2O3 core–shell composite functionalized by Fe–Mn–K via surface impregnation combustion: as-burnt catalysts for synthesis of light olefins from syngas
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DOI：
10.1039/c5ra25212a
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发表时间：
2016-01
期刊：
影响因子：
3.9
通讯作者：
Lupeng Han;Chunzheng Wang;Jianghong Ding;Guofeng Zhao;Ye Liu;Yong Lu
中科院分区：
文献类型：
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作者：
Lupeng Han;Chunzheng Wang;Jianghong Ding;Guofeng Zhao;Ye Liu;Yong Lu
有前途的微纤维结构Al-纤维@ns-Al2O3@Fe-Mn-K催化剂被开发用于轻质烯烃的传质/传热限制费托合成。 Al-fibre@ns-Al2O3核壳复合材料是在纳米到宏观尺度上设计的，首先通过在由10 vol% 60 μm Al纤维和90 vol%空隙率组成的3维微纤维结构网络上内生生长薄壳（~0.5 μm）纳米片γ-Al2O3（ns-Al2O3）来制备。通过浸渍法对Al-纤维@ns-Al2O3复合材料进行K改性后，通过表面浸渍燃烧法对纳米结构的Fe和Mn活性组分进行功能化。研究了燃烧气氛（空气、氮气、氮气后空气（N2-空气））对催化剂性能的影响。在空气下获得的燃烧态催化剂的铁时间产率最高，为 206.0 μmolCO gFe−1 s−1，CO 转化率为 89.6%，对 C2-C4 烯烃的 C 选择性为 42.1%（350 °C，4.0 MPa，10 000 mL（g−1 h−1）），而其他两种在 N2 和 N2-空气下燃烧态 CO 转化率相对较低58-67%。在空气中燃烧有助于形成具有更好还原性和碳化性能的 6 nm Fe-Mn-K 氧化物颗粒，从而获得高性能。相比之下，在氮气或氮气-空气气氛下，会形成较小的氧化物颗粒（3-4 nm），但由于载体与金属之间的强烈相互作用，还原性和碳化性能会恶化。在空气下获得的燃烧态催化剂也表现出良好的稳定性。
Promising microfibrous-structured Al-fiber@ns-Al2O3@Fe–Mn–K catalysts are developed for the mass/heat-transfer limited Fischer–Tropsch synthesis of light olefins. The Al-fiber@ns-Al2O3 core–shell composites, engineered on the nano- to macro-scale, are first prepared by endogenously growing thin shell (∼0.5 μm) nanosheet γ-Al2O3 (ns-Al2O3) onto the 3-dimentional microfibrous-structured network consisting of 10 vol% 60 μm Al-fiber and 90 vol% voidage. After modification by K through an impregnation method, the Al-fiber@ns-Al2O3 composites are functionalized with nano-structured Fe and Mn active components via a surface impregnation combustion method. The effect of combustion atmospheres (air, N2, and N2 followed by air (N2–air)) on the catalyst performance is investigated. The as-burnt catalyst obtained under air delivers the highest iron time yield of 206.0 μmolCO gFe−1 s−1 at 89.6% CO conversion with 42.1%C selectivity to C2–C4 olefins (350 °C, 4.0 MPa, 10 000 mL (g−1 h−1)), while the other two as-burnt catalysts under N2 and N2–air yield relatively low CO conversions of 58–67%. Combustion under air is helpful to form 6 nm Fe–Mn–K oxide particles with better reducibility and carbonization properties thereby leading to high performance. In contrast, under either N2 or N2–air atmosphere, smaller oxide particles (3–4 nm) are formed but suffer from deteriorated reducibility and carbonization properties due to the strong support–metal interaction. Such as-burnt catalysts obtained under air also demonstrate promising stability.