Deactivation behavior of ruthenium promoted Co/γ-Al2O3 catalysts in Fischer–Tropsch synthesis
Deactivation behavior of ruthenium promoted Co/γ-Al2O3 catalysts in Fischer–Tropsch synthesis
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DOI：
10.1016/j.apcata.2008.05.001
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发表时间：
2008-08
影响因子：
5.5
通讯作者：
A. Tavasoli;R. Abbaslou;A. Dalai
中科院分区：
文献类型：
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作者：
A. Tavasoli;R. Abbaslou;A. Dalai
考虑不同的失活机制，对用于费托合成 (FT) 合成的 Ru-Co/γ-Al2O3 催化剂在 1000 小时内的详细活性研究和失活进行了研究。采用XRD、TPR、BET、ICP、碳测定、H2化学吸附和再氧化技术研究了费托合成过程中催化剂的形貌变化。当反应器中的[式：见正文]高于0.75时，失活率不依赖于催化剂活性位点的数量，并且CO转化率为零级。在这种情况下，主要的失活机制是：钴再氧化、金属载体相互作用和铝酸盐形成。 Ru-Co/γ-Al2O3的失活与钴簇尺寸有关。在较低量的[公式：参见文本]下，可以使用幂次为 39.7 的幂律表达式来模拟失活，并且主要失活是由于烧结造成的。催化剂在275℃下再生，由于氧化钴的还原，催化剂活性恢复了总活性损失的69.9%。由于钴-氧化铝相互作用产生的难熔形式的氧化钴减少，400°C 下的催化剂再生恢复了总活性损失的 21.9%。总活性损失的 7.2% 是不可逆的，可归因于铝酸盐形成、烧结和焦炭沉积。
Detailed activity study and the deactivation of Ru-Co/γ-Al2O3catalyst for Fischer–Tropsch (FT) synthesis over 1000h was investigated considering different deactivation mechanisms. Morphology changes of the catalyst during FT synthesis were studied using XRD, TPR, BET, ICP, carbon determination, H2chemisorption and re-oxidation techniques. When the [Formula: see text] in the reactor is above 0.75 the deactivation rate is not dependent on the number of the catalyst active sites and is zero order to CO conversion. In this case the main deactivation mechanisms are: cobalt re-oxidation, metal support interactions and aluminates formation. The deactivation of Ru-Co/γ-Al2O3is related to cobalt cluster size. At lower amounts of [Formula: see text] deactivation can be simulated with a power law expression with a power order of 39.7 and the main deactivation is due to sintering. Regeneration of catalyst at 275°C recovered the catalyst activity by 69.9% of total activity loss due to the reduction of oxidized cobalts. Catalyst regeneration at 400°C recovered the activity by 21.9% of total activity loss due to the reduction of refractory forms of oxidized cobalt generated by cobalt–alumina interactions. 7.2% of total activity loss is irreversible and can be assigned to aluminates formation, sintering and coke deposition.