Temperature-programmed plasma surface reaction: An approach to determine plasma-catalytic performance
Temperature-programmed plasma surface reaction: An approach to determine plasma-catalytic performance
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DOI：
10.1016/j.apcatb.2018.08.011
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
A. Parastaev;W. Hoeben;Bert E.J.M. van Heesch;N. Kosinov;E. Hensen
中科院分区：
文献类型：
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作者：
A. Parastaev;W. Hoeben;Bert E.J.M. van Heesch;N. Kosinov;E. Hensen
由于等离子体和固体催化剂之间的协同作用，等离子体增强的多相催化为热催化提供了一种很有前途的替代方案。然而，对于高能电子和激发分子与等离子体中多相催化剂的相互作用，只有有限的力学见解。由于等离子体-催化剂系统的复杂性质，在等离子体-催化环境中进行准确的性能比较是复杂的：在气相和催化表面同时发生反应；放电对填充催化剂床层的介电性质的依赖；以及催化剂的介电常数和极化对等离子体参数的依赖。在这里，我们提出了一种程序升温等离子体表面反应(TPPSR)的方法，它允许将气相过程与表面等离子体诱导的反应分离。利用这种方法，我们揭示了二氧化碳加氢反应中等离子体与多相催化剂产生明显协同作用的主要原因。同位素标记的CO2实验和CO2/H_2流动中的程序升温等离子体反应实验证明，气相裂解/加氢对观察到的催化剂活性和选择性有很大的作用。放电参数对产物分布和反应路径的影响不大。考虑到催化剂床层的过热，以比较有无等离子体的催化活性，得出能量耗散也起重要作用。观察到的等离子体增强部分是由于电子诱导的表面反应的加速。
Plasma-enhanced heterogeneous catalysis offers a promising alternative to thermal catalysis due to the synergy between the plasma and the solid catalyst. However, there is only a limited mechanistic insight about the interactions of highly energetic electrons and excited molecules with heterogeneous catalysts in plasmas. Accurate performance comparison in a plasma-catalytic setting is complicated because of the intricate nature of the plasma-catalyst system: simultaneous reactions occurring in the gas-phase and at the catalytic surface; the dependence of the discharge on dielectric properties of the packed catalyst bed; and the dependence of permittivity and polarization of the catalyst on plasma parameters. Here, we present a method of temperature-programmed plasma surface reaction (TPPSR) that allows decoupling gas-phase processes from the surface plasma-induced reactions. Using this method we reveal the main reasons of apparent synergy between plasma and heterogeneous catalyst for the case of carbon dioxide hydrogenation. Experiments with isotopically labelled CO2and temperature-programmed plasma reaction experiments in flow of CO2/H2prove a substantial role of gas-phase dissociation/hydrogenation for the observed catalyst activity and selectivity. The product distribution and reaction pathways do not significantly depend on the discharge parameters. Taking into account overheating of the catalytic bed for comparison of catalytic activity with and without plasma, it was concluded that energy dissipation also plays an important role. The observed plasma enhancement is in part due to the acceleration of electron-induced surface reactions.