Effects of K-dopant on structure and activity of KMn/Al2O3 catalysts for CO oxidation: Experimental evidence and DFT calculation

Xie, Xiaopei; Tang, Qinghu; Zhang, Jia; Wang, Jing; Zhao, Pei-Zheng; Wang, Yi; Sullivan, Michael B.; Yang, Yanhui

doi:10.1016/j.apcata.2016.04.015

Cited by 7 publications

(1 citation statement)

References 49 publications

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“…The high catalytic activity of Mn oxides is based on the ability of Mn to easily change the oxidation state from 2+ to 4+, which leads to a high lattice oxygen storage capacity in the oxide [11,12]. In addition, Mn oxide catalysts supported on Al 2 O 3 , SiO 2 , CeO 2 , TiO 2 , (Ce,Zr)O 2 have been widely used in oxidation reactions [13][14][15][16][17][18][19][20][21][22][23]. This support affects the structural, microstructural, and redox properties of an Mn oxide catalyst due to the stabilization of Mn oxide nanoparticles on the surface of a support and the partial interaction with an active component [20,24].…”

Section: Introductionmentioning

confidence: 99%

Insights into the Contribution of Oxidation-Reduction Pretreatment for Mn0.2Zr0.8O2−δ Catalyst of CO Oxidation Reaction

et al. 2023

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A Mn0.2Zr0.8O2−δ mixed oxide catalyst was synthesized via the co-precipitation method and studied in a CO oxidation reaction after different redox pretreatments. The surface and structural properties of the catalyst were studied before and after the pretreatment using XRD, XANES, XPS, and TEM techniques. Operando XRD was used to monitor the changes in the crystal structure under pretreatment and reaction conditions. The catalytic properties were found to depend on the activation procedure: reducing the CO atmosphere at 400–600 °C and the reaction mixture (O2 excess) or oxidative O2 atmosphere at 250–400 °C. A maximum catalytic effect characterized by decreasing T50 from 193 to 171 °C was observed after a reduction at 400 °C and further oxidation in the CO/O2 reaction mixture was observed at 250 °C. Operando XRD showed a reversible reduction-oxidation of Mn cations in the volume of Mn0.2Zr0.8O2−δ solid solution. XPS and TEM detected the segregation of manganese cations on the surface of the mixed oxide. TEM showed that Mn-rich regions have a structure of MnO2. The pretreatment caused the partial decomposition of the Mn0.2Zr0.8O2−δ solid solution and the formation of surface Mn-rich areas that are active in catalytic CO oxidation. In this work it was shown that the introduction of oxidation-reduction pretreatment cycles leads to an increase in catalytic activity due to changes in the origin of active states.

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