Low-Temperature Restructuring of CeO2-Supported Ru Nanoparticles Determines Selectivity in CO2 Catalytic Reduction
Low-Temperature Restructuring of CeO2-Supported Ru Nanoparticles Determines Selectivity in CO2 Catalytic Reduction
复制标题
DOI：
10.1021/jacs.8b07615
复制
发表时间：
2018-10-24
影响因子：
15
通讯作者：
Cargnello, Matteo
中科院分区：
文献类型：
--
作者：
Aitbekova, Aisulu;Wu, Liheng;Cargnello, Matteo
将CO2减少到更高价值的产品是生产燃料和关键化学构件同时减少CO2排放的一种有前途的方法。常压下的反应主要通过甲烷化产生CH 4，通过逆水煤气变换（RWGS）反应产生CO。描述控制这两种途径的选择性的催化剂特征对于确定特定产物的形成是重要的。同时，识别在反应条件下催化剂发生的形态变化对于调节其催化性能至关重要。在这方面的贡献，我们调查的依赖性的Ru纳米粒子（NPs）的大小和支持的CO2还原的选择性。我们发现，即使在相当低的温度（210摄氏度），氧化预处理诱导再分散的Ru纳米粒子负载在CeO 2上，并导致这种材料的性能从一个众所周知的选择性甲烷化催化剂的活性和选择性RWGS催化剂的完全切换。通过利用原位X-射线吸收光谱，我们表明，低温再分散过程发生通过分解的金属氧化物相与尺寸相关的动力学，产生稳定的单站点RuOx/CeO 2物种强烈绑定到CeO 2支持，是显着的选择性CO生产。这些结果表明，反应选择性可能在很大程度上取决于催化剂结构，并且催化剂的结构变化甚至可以在低温下发生，并且可以在具有较少限定结构的材料中看不见。
CO2 reduction to higher value products is a promising way to produce fuels and key chemical building blocks while reducing CO2 emissions. The reaction at atmospheric pressure mainly yields CH4 via methanation and CO via the reverse water-gas shift (RWGS) reaction. Describing catalyst features that control the selectivity of these two pathways is important to determine the formation of specific products. At the same time, identification of morphological changes occurring to catalysts under reaction conditions can be crucial to tune their catalytic performance. In this contribution we investigate the dependency of selectivity for CO2 reduction on the size of Ru nanoparticles (NPs) and on support. We find that even at rather low temperatures (210 degrees C), oxidative pretreatment induces redispersion of Ru NPs supported on CeO2 and leads to a complete switch in the performance of this material from a well-known selective methanation catalyst to an active and selective RWGS catalyst. By utilizing in situ X-ray absorption spectroscopy, we demonstrate that the low-temperature redispersion process occurs via decomposition of the metal oxide phase with size dependent kinetics, producing stable single-site RuOx/CeO2 species strongly bound to the CeO2 support that are remarkably selective for CO production. These results show that reaction selectivity can be heavily dependent on catalyst structure and that structural changes of the catalyst can occur even at low temperatures and can go unseen in materials with less defined structures.