Operando Investigation of Toluene Oxidation over 1D Pt@CeO2 Derived from Pt Cluster-Containing MOF.
Operando Investigation of Toluene Oxidation over 1D Pt@CeO2 Derived from Pt Cluster-Containing MOF.
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DOI：
10.1021/jacs.0c08640
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发表时间：
2020-12
影响因子：
15
通讯作者：
Qingyue Wang;Yuxin Li;A. Serrano-Lotina;Wei Han;R. Portela;Ruixuan Wang;M. Bañares;K. Yeung
中科院分区：
文献类型：
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作者：
Qingyue Wang;Yuxin Li;A. Serrano-Lotina;Wei Han;R. Portela;Ruixuan Wang;M. Bañares;K. Yeung
由 Pt@CeBDC MOF 制备了独特的一维 Pt@CeO2-BDC 纳米结构。 Pt@CeO2-BDC富含氧空位（即XPS Oβ/(Oα + Oβ) = 39.4%），在催化剂上，2 nm的Pt团簇均匀沉积在一维介孔多晶CeO2上。在光谱操作拉曼在线 FTIR 反应器中进行甲苯氧化，以阐明反应机理并建立构效关系。反应进行如下：（I）通过与表面过氧化物物质反应，在低温下将甲苯作为苯甲酸酯中间体吸附在Pt@CeO2-BDC上； (II)涉及晶格氧的反应活化和开环，伴随着表明表面重排的缺陷密度的变化； (III)通过晶格氧完全氧化成CO2和H2O，并且随着吸附氧的消耗，还原的二氧化铈被再氧化。 Pt簇主要以Pt2+形式存在，表面有少量Pt0和Pt4+，有利于吸附和反应活化。 Pt-CeO2 界面产生还原的二氧化铈位点，在低温下在附近形成吸附的过氧化物，通过 Langmuir-Hinshelwood 机制将甲苯氧化成苯甲酸盐物质。随着反应温度升高，晶格氧的作用变得重要，主要通过Mars-van Krevelen机制产生CO2和H2O。
A unique 1D nanostructure of Pt@CeO2-BDC was prepared from Pt@CeBDC MOF. The Pt@CeO2-BDC was rich in oxygen vacancies (i.e., XPS Oβ/(Oα + Oβ) = 39.4%), and on the catalyst, the 2 nm Pt clusters were uniformly deposited on the 1D mesoporous polycrystalline CeO2. Toluene oxidation was conducted in a spectroscopic operando Raman-online FTIR reactor to elucidate the reaction mechanism and establish the structure-activity relationship. The reaction proceeds as follows: (I) adsorption of toluene as benzoate intermediates on Pt@CeO2-BDC at low temperature by reaction with surface peroxide species; (II) reaction activation and ring-opening involving lattice oxygen with a concomitant change in defect densities indicative of surface rearrangement; (III) complete oxidation to CO2 and H2O by lattice oxygen and reoxidation of the reduced ceria with consumption of adsorbed oxygen species. The Pt clusters, which mainly exist as Pt2+ with minor amounts of Pt0 and Pt4+ on the surface, facilitated the adsorption and reaction activation. The Pt-CeO2 interface generates reduced ceria sites forming nearby adsorbed peroxide at low temperature that oxidize toluene into benzoate species by a Langmuir-Hinshelwood mechanism. As the reaction temperature increases, the role of lattice oxygen becomes important, producing CO2 and H2O mainly by the Mars-van Krevelen mechanism.