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First Author: CHEN Xi

A series of MnOx/Cr2O3 composites have been prepared via the combination methods of impregnation, in situ redox precipitation and pyrolysis based on MIL-101-Cr. The physicochemical properties of catalysts have been investigated by using XRD, Raman, BET, SEM, TEM, XPS, H2-TPD and O2-TPD, and their catalytic performance has been evaluated by toluene combustion. With introduction of MnOx into Cr2O3, the MnOx/Cr2O3-M exhibits the obviously enhanced catalytic activity for toluene oxidation compared to commercial Cr2O3 or pure Cr2O3 pyrolyzed by MIL-101-Cr. The 14.6 wt% MnOx/Cr2O3-M (named as 15Mn/Cr2O3-M) shows the highest efficiency and lowest Ea values under different SV and toluene concentrations. The catalytic durability test for toluene oxidation on 15Mn/Cr2O3-M presents a solid stability, where the toluene conversion maintains at ca. 85% for at least 240 h without obvious inactivation (270 °C, 1000 ppm of toluene, 20,000 mL/(g h), with 10 vol% of water vapor) and it can also maintain at conversions of 90% and 50% for at least 50 h with higher space velocity (1000 ppm of toluene, 60,000 mL/(g h)). The good durability and tolerance of 15Mn/Cr2O3-M are probably associated with better stability for crystal structure, oxygen vacancies, and reducibility. More MnOx addition amount (25Mn/Cr2O3-M) cannot further promote catalytic performance, possibly due to excessive MnOx existed as isolated phase with lack of strong interaction between two metal oxides. The investigation of in situ DRIFTS on 15Mn/Cr2O3-M confirms that surface lattice oxygen OLatt plays a crucial role in toluene combustion and the pathway for toluene combustion is via rapid transformation to aldehydic and then benzoate species and finally form CO2 and H2O.

Contact the author: JIA Hongpeng
Page Number: 312-324
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PubYear: MAY 2019
Volume: 475
The full text link: https://doi.org/10.1016/j.apsusc.2018.12.277