کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
40889 | 45869 | 2012 | 8 صفحه PDF | دانلود رایگان |

The rod-like tetragonal α-MnO2, flower-like hexagonal ɛ-MnO2, and dumbbell-like tetragonal β-MnO2 were prepared using the hydrothermal or water-bathing method under different conditions. It is shown that the α-MnO2, ɛ-MnO2, and β-MnO2 catalysts possessed a surface area of ca. 53, 30, and 114 m2/g, respectively. The oxygen adspecies concentration and low-temperature reducibility decreased in the order of α-MnO2 > ɛ-MnO2 > β-MnO2, coinciding with the sequence of their catalytic activities for toluene combustion. The well-defined morphological MnO2 catalysts performed much better than the bulk counterpart. At a space velocity of 20,000 mL/(g h), the temperature for 90% toluene conversion was 238, 229, and 241 °C over α-MnO2, ɛ-MnO2, and β-MnO2, respectively. The apparent activation energies of α-MnO2, ɛ-MnO2, and β-MnO2 were in the range of 20–26 kJ/mol. It is concluded that higher oxygen adspecies concentrations and better low-temperature reducibility were responsible for the good catalytic performance of the α-MnO2, ɛ-MnO2, and β-MnO2 materials.
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► α-, ɛ-, and β-MnO2 with various shapes are prepared by hydrothermal or water-bathing method.
► Rod-like α-MnO2, flower-like ɛ-MnO2, and dumbbell-like β-MnO2 show a surface area of 30–114 m2/g.
► Well-defined morphological MnO2 possess high Oads concentrations and good reducibility.
► Rod-, flower-, and dumbbell-like MnO2 catalysts perform well for toluene combustion.
► High Oads concentration and good reducibility account for the good catalytic activity.
Journal: Applied Catalysis A: General - Volumes 433–434, 8 August 2012, Pages 206–213