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首页> 外文期刊>Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications >Dry reforming of methane to test passivation stability of Ni/ Al2O3 catalysts
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Dry reforming of methane to test passivation stability of Ni/ Al2O3 catalysts

机译：甲烷干燥重整为Ni / Al2O3催化剂的钝化稳定性

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Catalyst passivation refers to the formation of a protective oxide layer on the active metal particles that prevents their oxidation when exposed to air. Common passivation procedures, when applied to Ni/ Al2O3 catalysts, typically result in a significant decrease of the overall Ni surface area and, accordingly, the catalytic activity. Nevertheless, passivation and reactivation is an attractive pre-treatment option for this system. Ni/ Al2O3 typically requires reduction temperatures much higher than the desired reaction temperature, whereas reactivation of passivated samples is a low-temperature reduction. This can be used to avoid temperature limitations of existing systems. Thus, more insight into the passivation process of this system is desirable. In this work we analyzed the impact of passivation on the catalytic performance of a series of Ni/ Al2O3 catalysts in dry reforming of methane. This approach allows for the elimination of scale effects during passivation. We show that changes in conversion and especially of the coke content can be used to track sintering of Ni particles. These metrics allows to identify an adverse effects of catalyst passivation in excess O2, which gives rise to rapid local overheating and, accordingly, Ni sintering even when operating at tens of mg catalyst scale. Our study demonstrates that such problems are not limited to scaling issues and sufficient care must be taken even on a lab-scale when passivating Ni/ Al2O3 catalysts.
机译：催化剂钝化是指在活性金属颗粒上形成保护性氧化层，防止其暴露在空气中时氧化。当应用于Ni/Al2O3催化剂时，常用的钝化程序通常会导致整体Ni表面积显著降低，从而导致催化活性显著降低。然而，钝化和再活化是该系统一个有吸引力的预处理选项。Ni/Al2O3通常需要比预期反应温度高得多的还原温度，而钝化样品的再活化是低温还原。这可以用来避免现有系统的温度限制。因此，需要更多地了解该系统的钝化过程。在这项工作中，我们分析了钝化对一系列Ni/Al2O3催化剂在甲烷干重整中催化性能的影响。这种方法可以消除钝化过程中的氧化皮效应。我们发现，转化率的变化，尤其是焦炭含量的变化，可以用来跟踪镍颗粒的烧结。这些指标允许识别过量O2中催化剂钝化的不利影响，这会导致快速局部过热，因此，即使在以数十mg催化剂规模运行时，镍也会烧结。我们的研究表明，这些问题不仅限于结垢问题，在钝化Ni/Al2O3催化剂时，即使在实验室规模上也必须足够小心。

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