Crystalline Mesoporous K2–xMn8O16 and ε‑MnO2 by Mild Transformations of Amorphous Mesoporous Manganese Oxides and Their Enhanced Redox Properties
journal contributionposted on 23.07.2014 by Altug S. Poyraz, Wenqiao Song, David Kriz, Chung-Hao Kuo, Mohammad S. Seraji, Steven L. Suib
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Synthesis of crystalline mesoporous K2–xMn8O16 (Meso-OMS-2), and ε-MnO2 (Meso-ε-MnO2) is reported. The synthesis is based on the transformation of amorphous mesoporous manganese oxide (Meso-Mn-A) under mild conditions: aqueous acidic solutions (0.5 M H+ and 0.5 M K+), at low temperatures (70 °C), and short times (2 h). Meso-OMS-2 and Meso-ε-MnO2 maintain regular mesoporosity (4.8–5.6 nm) and high surface areas (as high as 277 m2/g). The synthesized mesoporous manganese oxides demonstrated enhanced redox (H2-TPR) and catalytic performances (CO oxidation) compared to nonporous analogues. The order of reducibility and enhanced catalytic performance of the samples is Commercial-Mn2O3 < nonporous-OMS-2 < Meso-Mn2O3 < Meso-OMS-2 < Meso-ε-MnO2 < Meso-Mn-A.