Effect of oxygen storage materials on the performance of Pt-based three-way catalysts
Effect of oxygen storage materials on the performance of Pt-based three-way catalysts
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储氧材料对Pt基三元催化剂性能的影响
DOI：
10.1039/d2cy00469k
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Toyao Takashi
中科院分区：
文献类型：
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作者：
Wang Gang;Jing Yuan;Ting Kah Wei;Maeno Zen;Zhang Xiaorui;Nagaoka Shuhei;Shimizu Ken-ichi;Toyao Takashi
目前Pt的成本低于Pd和Rh，但是Pt基三元催化剂（TWCs）却没有Pd基和Rh基三元催化剂那么受关注。因此，对基于pt的TWCs性质的基本理解仍然不足。在此，我们通过各种光谱观察结合动力学研究，证明了氧存储材料（OSMs），包括CeO2和CeO2 - zro2固溶体，具有不同的铈含量（20%，45%和66%），对Pt/OSMs的三向催化性能的影响。在粉状催化剂和蜂窝状催化剂的对比评价中，新鲜Pt/OSM（100%CeO2）和老化Pt/OSM（66%CeO2）的NO转化率最高，表明Pt/OSM（66%CeO2）是最具发展前景和稳定性的TWCs。原位CO吸附红外（IR）光谱和x射线光电子能谱（XPS）分析表明，负载在高铈含量osm上的Pt0物质更缺电子。Operando IR和动力学研究表明，增加新鲜Pt/OSMs中铈的含量不仅增强了亚硝酸盐的形成及其对CO的反应活性，而且增强了NO-CO反应中对CO中毒的抗性。原位x射线吸收光谱（XAS）结果表明，Pt/OSM催化剂中的Ce和Pt都通过氧化还原循环参与了NO-CO反应。原位XAS结合x射线衍射（XRD）结果表明，水热老化处理导致Pt/OSMs中Pt粒子聚集，CeO2晶格收缩，严重降低了Pt和Ce的氧化还原能力，降低了铈对亚硝酸盐形成的促进作用及其对CO的反应性。
The cost of Pt is currently lower than that of Pd and Rh, however, Pt-based three-way catalysts (TWCs) have attracted less attention than Pd- and Rh-based TWCs. Consequently, the fundamental understanding of the properties of Pt-based TWCs remains insufficient. Herein, we demonstrate the effect of oxygen storage materials (OSMs), including CeO2 and CeO2–ZrO2 solid-solutions having different ceria contents (20%, 45%, and 66%), on the three-way catalysis performance of Pt/OSMs using various spectroscopic observations in combination with kinetic studies. In comparative assessments of powdered and monolithic (honeycomb) catalysts, fresh Pt/OSM(100%CeO2) and aged Pt/OSM(66%CeO2) exhibited the highest NO conversion among their corresponding series, showing that Pt/OSM(66%CeO2) is the most promising and stable among the TWCs. In situ CO adsorption infrared (IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) revealed that the Pt0 species loaded on OSMs having a higher ceria content were more electron-deficient. Operando IR and kinetic investigations suggested that increasing the ceria content in fresh Pt/OSMs enhanced not only the formation of nitrite species and their reactivity toward CO but also the resistance to CO poisoning during NO–CO reactions. In situ X-ray absorption spectroscopy (XAS) indicated that both Ce and Pt species in Pt/OSM catalysts are involved in NO–CO reactions through their redox cycles. In situ XAS in combination with X-ray diffraction (XRD) measurements revealed that the hydrothermal ageing treatment resulted in the aggregation of Pt particles and lattice contraction of CeO2 in Pt/OSMs, causing severe degradation of the redox ability of Pt and Ce species and reducing the promoting effect of ceria on the formation of nitrites and their reactivity toward CO.