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Issue 22, 2018
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Rare-earth element doping-promoted toluene low-temperature combustion over mesostructured CuMCeOx (M = Y, Eu, Ho, and Sm) catalysts: the indispensable role of in situ generated oxygen vacancies

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Abstract

Novel CuMCeOx (M = Y, Eu, Ho, and Sm) trimetal oxide catalysts with developed mesoporosity and an enhanced oxygen migration capability were fabricated by a reproducible self-precipitation approach for the first time. The incorporation of a rare-earth element (especially Y, Eu, and Ho) can increase the reducibility of, and mobility of surface adsorbed oxygen on, a CuCeOx catalyst, which leads to a remarkable increase in catalytic activity in the oxidation of toluene. Among these catalysts, the CuHoCeOx catalyst possesses the highest oxidation activity, with the complete mineralization of toluene at 220 °C at a relatively high GHSV of 50 000 h−1, which is ascribable to the synergetic effect of Ho and the CuCeOx framework, which creates abundant active oxygen vacancies over mixed oxides. Raman spectroscopy and density functional theory (DFT) studies reveal that Ho element is coordinated to two oxygen atoms and occupies the site of a Ce atom, which changes the π-bonding of Ce in the CuCeOx binary oxide and thus leads to the weakening of Ce–O bonds and an enhanced oxygen storage capacity. A possible reaction pathway and a mechanism for the combustion of toluene over a CuHoCeOx sample are proposed by means of in situ DRIFTS and DFT studies, which prove that the toluene oxidation process obeys the Mars–van Krevelen mechanism, with aldehydes and ketones as the primary organic intermediates, before decomposition to CO2 and H2O.

Graphical abstract: Rare-earth element doping-promoted toluene low-temperature combustion over mesostructured CuMCeOx (M = Y, Eu, Ho, and Sm) catalysts: the indispensable role of in situ generated oxygen vacancies

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Publication details

The article was received on 04 Sep 2018, accepted on 16 Oct 2018 and first published on 16 Oct 2018


Article type: Paper
DOI: 10.1039/C8CY01849A
Citation: Catal. Sci. Technol., 2018,8, 5933-5942
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    Rare-earth element doping-promoted toluene low-temperature combustion over mesostructured CuMCeOx (M = Y, Eu, Ho, and Sm) catalysts: the indispensable role of in situ generated oxygen vacancies

    Z. Jiang, C. Chen, M. Ma, Z. Guo, Y. Yu and C. He, Catal. Sci. Technol., 2018, 8, 5933
    DOI: 10.1039/C8CY01849A

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