Operando Electron Microscopy Study of Cobalt‐based Fischer‐Tropsch Nanocatalysts,ChemCatChem

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Operando Electron Microscopy Study of Cobalt‐based Fischer‐Tropsch Nanocatalysts
ChemCatChem ( IF 3.8 ) Pub Date : 2020-11-19 , DOI: 10.1002/cctc.202001074
Kassiogé Dembélé _{1,

2} , Mounib Bahri ₁ , Charles Hirlimann ₁ , Simona Moldovan ₁ , Adrien Berliet ₂ , Sylvie Maury ₂ , Anne‐Sophie Gay ₂ , Ovidiu Ersen _{1,

3}

Affiliation

Thanks to their stability and selectivity for long‐chains hydrocarbons, supported Co nanoparticles are the most commonly used catalysts in the Fischer‐Tropsch synthesis reaction. We report here on the use of in situ transmission electron microscopy (TEM) to address the real‐time evolution of cobalt‐based catalysts during their reduction under relevant industrial activation condition (10⁵ Pa, 430 °C), and their operation in syngas (H₂/CO=2, 10⁵ Pa, 220 °C). To do so, we chose Co₃O₄−Pt nanoparticles supported on silica or alumina that can be directly compared to some industrial catalysts. By analysing the real space information contained in the TEM images, we have monitored the fragmentation of cobalt aggregates, the disappearance of cavities within the particles, their shape changes, the particle diffusion and coalescence processes, as well as the effect of the support (silica or alumina) on the behaviour of the Co phase. An easier reduction of cobalt catalysts supported on silica as compared to the same catalyst supported on alumina was also observed. During the catalyst operation under syngas, we have noticed the stability of the general shape of the particles. Simultaneously, using a residual gas analyser connected to the TEM holder, the main gas products of the Fischer‐Tropsch reaction were systematically analysed. Our findings underline the benefit of the operando TEM to study the dynamical evolution of catalysts, at the nanoparticle level, under operation conditions.

中文翻译：

钴基费托纳米催化剂的Operando电子显微镜研究

由于其对长链烃的稳定性和选择性，负载型Co纳米颗粒是费托合成反应中最常用的催化剂。我们在此报告使用原位透射电子显微镜（TEM）解决钴基催化剂在相关工业活化条件（10 ⁵ Pa，430°C）下还原过程中的实时演变及其在合成气中的操作（H ₂ / CO = 2，10 ⁵ Pa，220°C）。为此，我们选择了Co ₃ O ₄负载在二氧化硅或氧化铝上的铂纳米颗粒可以直接与某些工业催化剂进行比较。通过分析TEM图像中包含的真实空间信息，我们监测了钴聚集体的破碎，颗粒内部空洞的消失，它们的形状变化，颗粒扩散和聚结过程以及载体（二氧化硅）的作用。或氧化铝）。还观察到与负载在氧化铝上的相同催化剂相比，负载在二氧化硅上的钴催化剂更容易还原。在合成气下的催化剂操作过程中，我们注意到了颗粒总体形状的稳定性。同时，使用连接到TEM支架的残留气体分析仪，系统地分析了Fischer-Tropsch反应的主要气体产物。操作TEM以研究催化剂在操作条件下在纳米粒子水平上的动力学演变。

更新日期：2020-11-19

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