A modular high-temperature cell consisting of a plug-flow microreactor with a fixed catalyst bed and long heating zone has been established for operando x-ray absorption/fluorescence spectroscopic and diffraction studies. The functionality of the cell is demonstrated for two important areas: emission control using 2 wt. % Pd/Al₂O₃ acting as a three-way catalyst and direct conversion of methane to olefins and aromatics on a 0.5% Fe/SiO₂ catalyst. The performance has been determined by online infrared spectroscopy and mass spectrometry, respectively. In addition, the cell can be combined with optical spectroscopy, such as Raman spectroscopy. The catalyst, present as powdered/sieved samples, can be measured under reaction conditions at temperatures of up to 1050 °C. Another key aspect is a long isothermal heating zone with a small temperature gradient (<3 °C/mm at 1000 °C without reaction) including an inert zone for pre-heating of the reactant gas. Due to the small size of the microreactor and the heating system including a water cooling system, heating/cooling rates of up to 100 °C/min can be achieved. Moreover, due to the compact design and the autonomous control system, the high temperature operando setup fits to the space at the majority of synchrotron beamlines. In many cases, the concentration of the element of interest in the catalysts is low requiring x-ray absorption spectroscopy measurements in the fluorescence measurement mode. Hence, the microreactor was designed to fit such needs as well. More specifically, the case of Fe-containing catalysts was particularly considered by using iron-free materials for the reactor housing.

中文翻译：

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用于多相催化剂的全荧光和透射X射线吸收光谱研究的多功能和高温光谱池

已经建立了由带有固定催化剂床和长加热区的活塞流微反应器组成的模块化高温池，用于操作X射线吸收/荧光光谱和衍射研究。该电池的功能在两个重要领域得到了证明：使用2 wt。％的二氧化碳进行排放控制。％Pd / Al ₂ O ₃充当三元催化剂，并在0.5％Fe / SiO ₂上将甲烷直接转化为烯烃和芳烃催化剂。该性能已分别通过在线红外光谱法和质谱法确定。另外，该池可以与光谱学例如拉曼光谱学结合。以粉末/筛分样品形式存在的催化剂可以在高达1050°C的反应条件下进行测量。另一个关键方面是长的等温加热区，其温度梯度小（在没有反应的情况下，在1000°C时<3°C / mm），其中包括用于预热反应气体的惰性区。由于微型反应器和包括水冷却系统在内的加热系统尺寸较小，因此可以实现高达100°C / min的加热/冷却速率。此外，由于紧凑的设计和自主控制系统，高温操作装置适合大多数同步加速器光束线的空间。在许多情况下，催化剂中目标元素的浓度较低，需要在荧光测量模式下进行X射线吸收光谱测量。因此，微反应器也被设计来满足这种需求。更具体地，通过将​​无铁材料用于反应器壳体，特别考虑了含铁催化剂的情况。