Coke evolution in simulated bio-oil aqueous fraction steam reforming using Co/SBA-15
Coke evolution in simulated bio-oil aqueous fraction steam reforming using Co/SBA-15
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DOI：
10.1016/j.cattod.2020.04.069
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发表时间：
2021-04-07
期刊：
影响因子：
5.3
通讯作者：
Carrero, A.
中科院分区：
文献类型：
--
作者：
Megia, P. J.;Vizcaino, A. J.;Carrero, A.
本文研究了来自生物质 HTL 的生物油水相馏分的模型化合物在蒸汽重整过程中 Co/SBA-15 催化剂的失活情况。我们观察了失活是如何在两个明显不同的阶段发生的。在第一个（TOS 20 小时）中，转化率急剧下降，从 XRD 推断出 Co 烧结，并且观察到焦炭沉积导致的孔隙堵塞。在第一阶段，焦炭似乎是丝状的，并且可以通过 TEM 观察到一些封装的 Co 颗粒。封装焦炭减少了催化重整反应的可及中心的数量。在第二阶段（TOS 20 小时），也观察到丝状焦炭，但更加浓缩，因此芳香性更强，元素分析确定的较高 C/H 比证实了这一点。在此阶段，尽管沉积的焦炭量增加，但没有观察到比表面积的下降。此外，由于在 XRD 图中没有检测到与氧化钴相对应的峰，因此催化剂失活不能归因于金属活性位点的氧化。 t-Student统计分析表明，Co/SBA-15催化剂失活主要受焦炭沉积量及其C/H比的影响。
This paper studies Co/SBA-15 catalyst deactivation during the steam reforming of model compounds from the aqueous fraction of bio-oil coming from biomass HTL. We observed how deactivation took place in two clearly differentiated stages. In the first one (TOS 20 h), where conversion decreased strongly, Co sintering deduced from XRD and, pore blockage by coke deposition were observed. At this first stage, coke seemed to be filamentous and some encapsulated Co particles could be appreciated by TEM. The encapsulating coke reduced the number of accessible centers to catalyze the reforming reaction. In the second stage (TOS 20 h), filamentous coke was also observed but more condensed and therefore more aromatic, as verified by higher C/H ratio determined by elemental analysis. In this stage, despite the amount of coke deposited was growing, no drop on specific surface area was observed. Besides, since no peaks corresponding to cobalt oxides were detected in the XRD patterns, catalyst deactivation cannot be attributed to metallic active sites oxidation. The t-Student statistical analysis showed that Co/SBA-15 catalyst deactivation is mainly affected by the amount of coke deposited and its C/H ratio.