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Investigation of the re-dispersion of matrix Cu species in CuxCe1−xO2 nanorod catalysts and its effect on the catalytic performance in CO-PROX
Catalysis Science & Technology ( IF 5 ) Pub Date : 2020-06-18 , DOI: 10.1039/d0cy00519c
Xiaolin Guo 1, 2, 3, 4 , Wangxiang Ye 1, 2, 3, 4 , Tingli Ma 1, 2, 3, 4, 5
Affiliation  

In the present work, CuxCe1−xO2 nanorod catalysts synthesized by a co-precipitation method were treated with nitric acid to remove all the surface copper species and merely preserve the matrix copper species in the framework of ceria. With the subsequent thermal treatment at various temperature, the re-dispersion phenomenon of the matrix copper was investigated to different degrees and showed a profound influence on the catalytic performance in CO-PROX. Various analysis methods (XRD Rietveld refinement, HRTEM, XPS, H2-TPR and in situ DRIFTs) were used to characterize the texture/structure property, redox property and surface element distribution of the catalyst along with the re-dispersion process. The acid-treated process not only diminished the active copper species for CO adsorption but also destroyed the surface oxygen vacancy, which severely damaged the low-temperature CO oxidation activity of H–CuCe(rod). Motivated by the thermal treatment, the matrix copper species shifts from the framework to the surface region, and is dispersed as surface CuOx species. In cooperation with the recovered oxygen vacancy, the interfacial interaction between copper and ceria was rebuilt and the catalytic performance of H–CuCe(rod) was remarkably enhanced with higher CO conversion (T50%: 137 °C to 80 °C) and a broader temperature window (width: zero to 50 °C). With further elevating the calcination temperature, much more matrix copper species was re-dispersed as surface CuOx species and further stimulated the low-temperature CO oxidation activity of H–CuCe(rod)-600. However, the deficiency of the matrix copper interacting with the ceria lattice and the reduced oxygen vacancy concentration led to a rapid decrease in CO conversion at high temperature and narrowed the temperature window for H–CuCe(rod)-600 in the preferential oxidation of CO (CO-PROX). Our findings reveal that the CO-PROX performance of a shape-controlled copper–ceria catalyst is highly sensitive to the distribution of copper species and could be regulated by the acid and subsequent thermal treatment process, providing a new insight into the development of highly efficient copper–ceria catalysts for CO-PROX.

中文翻译:

CuxCe1-xO2纳米棒催化剂中基质Cu种类的再分散及其对CO-PROX催化性能的影响

在目前的工作中,用硝酸处理通过共沉淀法合成的Cu x Ce 1- x O 2纳米棒催化剂,以去除所有表面铜物种,而仅将基体铜物种保留在二氧化铈的骨架中。通过随后在不同温度下进行的热处理,对基质铜的再分散现象进行了不同程度的研究,并对CO-PROX中的催化性能产生了深远的影响。各种分析方法(XRD Rietveld精炼,HRTEM,XPS,H 2 -TPR和原位分析用DRIFTs表征催化剂的质地/结构性质,氧化还原性质和表面元素分布以及再分散过程。酸处理过程不仅减少了活性铜吸附CO的种类,而且破坏了表面氧的空位,严重破坏了H-CuCe(棒)的低温CO氧化活性。在热处理的推动下,基体铜物质从骨架转移到表面区域,并以表面CuO x物质的形式分散。与回收的氧空位配合,可重建铜与二氧化铈之间的界面相互作用,并通过较高的CO转化率显着提高H–CuCe(棒)的催化性能(T 50%:137°C至80°C)和更宽的温度范围(宽度:0至50°C)。随着煅烧温度的进一步升高,更多的基体铜物质被重新分散为表面CuO x。物种并进一步刺激了H–CuCe(rod)-600的低温CO氧化活性。然而,基质铜与二氧化铈晶格相互作用的缺陷以及氧空位浓度的降低导致高温下CO转化率迅速下降,并导致CO优先氧化过程中H–CuCe(rod)-600的温度窗口变窄。 (CO-PROX)。我们的发现表明,形状受控的铜-二氧化铈催化剂的CO-PROX性能对铜的分布高度敏感,并且可以通过酸和随后的热处理工艺进行调节,从而为高效开发提供了新见解。 CO-PROX的二氧化铈铜催化剂。
更新日期:2020-07-21
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