The Properties of Individual Carbon Residuals and Their Influence on The Deactivation of Ni–CaO–ZrO2 Catalysts in CH4 Dry Reforming
The Properties of Individual Carbon Residuals and Their Influence on The Deactivation of Ni–CaO–ZrO2 Catalysts in CH4 Dry Reforming
复制标题
DOI：
10.1002/cctc.201300754
复制
发表时间：
2014-02
期刊：
影响因子：
4.5
通讯作者：
Changzhen Wang;Nannan Sun;N. Zhao;Wei Wei-Wei;Jun Zhang;T. Zhao;Yuhan Sun;Cheng-gong Sun;Hao Liu;C. Snape
中科院分区：
文献类型：
--
作者：
Changzhen Wang;Nannan Sun;N. Zhao;Wei Wei-Wei;Jun Zhang;T. Zhao;Yuhan Sun;Cheng-gong Sun;Hao Liu;C. Snape
制备了不同性质的Ni-CaO-ZrO2催化剂，并对甲烷二氧化碳重整反应进行了考察。通过透射电子显微镜、热重分析、拉曼光谱、X-射线光电子能谱、X-射线衍射仪对催化剂进行了表征，揭示了它们在重整反应中的不同性质和积炭行为。结果表明，采用共沉淀法和加热回流陈化法制备的催化剂具有纳米晶结构，具有较强的金属-载体相互作用，具有较高的活性和稳定性，但也表现出最高的成炭速率。这一结果表明，催化剂的失活可能不一定与生成的碳量相关，残炭的个别性质可能起到更决定性的作用。不同催化剂上的残炭分别为无定形碳、包埋碳、晶须碳和石墨，它们对失活的影响不同。在活性最高、稳定性最好的催化剂表面，碳物种主要由无定形碳和晶须碳组成，表明这种碳物种的形成并不一定会导致催化剂失活。相反，催化剂的失活与包覆在催化剂表面的碳和石墨的形成密切相关。不同残炭的积累遵循形成-扩散/消除的过程，这一过程受到Ni颗粒大小和Ni-ZrO2相互作用的显著影响。
Ni–CaO–ZrO2 catalysts with different properties were prepared and tested for CO2 reforming of methane. The catalysts were characterized by means of transmission electron microscopy, thermogravimetric analysis, Raman spectroscopy, X‐ray photoelectron spectroscopy, and X‐ray diffraction to reveal their distinct properties and carbon deposition behaviors in the reforming reaction. It was found that the catalyst prepared by a coprecipitation method and ageing by heating to reflux exhibited a nanocrystalline structure with strong metal–support interaction, which was responsible for both high activity and stability, but it also exhibited the highest carbon formation rate among the tested catalysts. This result suggests that catalyst deactivation might not necessarily correlate with the amount of formed carbon, and the individual properties of carbon residuals could play a more decisive role. Carbon residuals on different catalysts were identified as amorphous carbon, encapsulating carbon, whisker carbon, and graphite, which had different influence on the deactivation. On the surface of the most active and stable catalyst, the carbon species mainly consisted of amorphous and whisker carbon, suggesting that the formation of such carbon species does not necessarily lead to catalyst deactivation. In contrast, the deactivation was found to be closely related to the formation of encapsulating carbon and graphite, which could coat the catalyst surface. The accumulation of different carbon residuals was proven to follow a formation–diffusion/elimination scenario, which was significantly influenced by the Ni particle size and Ni–ZrO2 interactions.