Highly Effective Direct Decomposition of Nitric Oxide by Microwave Catalysis over BaMeO₃ (Me=Mn, Co, Fe) Mixed Oxides at Low Temperature under Excess Oxygen

Abstract

The direct catalytic decomposition of NO with high activity and N2 selectivity is a great challenge at low temperature under excess oxygen. Herein, we report the NO decomposition by microwave catalysis over BaMeO3 (Me=Mn, Co, Fe) mixed oxides for the first time at low temperature under excess oxygen, for which the BaCoO3 catalyst has an outstanding activity with a high NO conversion and N2 selectivity up to 99.8 % and 99.9 %, respectively, even at 250 °C. Comparatively, the best NO conversion is 93.7 % for BaMnO3 and only 64.1 % for BaFeO3 under microwave irradiation. H2 temperature‐programmed reduction, O2 temperature‐programmed desorption, and the microwave‐absorbing properties of the mixed oxides were characterized to illustrate possible reasons that cause such clear differences in the catalytic performance. Importantly, the apparent activation energies for BaMnO3, BaCoO3, and BaFeO3 are as low as 33.4, 13.7, and 46.7 kJ mol−1, respectively, which suggests a significant microwave catalytic effect.

Microwave Irradiation Coupled with MeOx/Al2O3 (Me=Cu, Mn, Ce) Catalysts for Nitrogen Monoxide Removal from Flue Gas at Low Temperatures

“…The oxygen concentration does not influence the catalytic activity of the MeO x /Al 2 O 3 catalysts for the direct decomposition of NO in the MCRM. This phenomenon is in accordance with our previous works . The microwave selectivity effect under microwave irradiation may account for this phenomenon.…”

“…It is widelya cknowledged that polar molecules can be activated by microwave electromagnetic fields. [29,34,49] As reported by previous studies from our group [42,44,45,50,51] and others, [34,41] NO molecules adsorbed on the active sites Energy Technol. 2016, 4, 856 -863 2 016Wiley-VCH Verlag GmbH &Co. KGaA,W einheim (rather than O 2 molecules in the gas phase) can be activated effectively by the microwave electromagnetic field.…”

“…It is widely acknowledged that polar molecules can be activated by microwave electromagnetic fields . As reported by previous studies from our group and others, NO molecules adsorbed on the active sites (rather than O 2 molecules in the gas phase) can be activated effectively by the microwave electromagnetic field. Although both O 2 and NO molecules can be physically adsorbed on the active sites, only NO molecules with physical adsorption on the active sites of the catalysts in the MCRM can transition into chemical adsorption and subsequently form N 2 and O 2 .…”

“…As reported by previous studies from our group and others, NO molecules adsorbed on the active sites (rather than O 2 molecules in the gas phase) can be activated effectively by the microwave electromagnetic field. Although both O 2 and NO molecules can be physically adsorbed on the active sites, only NO molecules with physical adsorption on the active sites of the catalysts in the MCRM can transition into chemical adsorption and subsequently form N 2 and O 2 . At the same time, the physical adsorption of O 2 molecules is not enough to be activated at such a low temperatures due to the microwave‐selectivity effect, which inhibits their reactivity with NO to generate NO 2 .…”

“…This phenomenon is in accordance with our previous works. [44,45,50] Them icrowave selectivity effect under microwave irradiationm ay account for this phenomenon. It is widelya cknowledged that polar molecules can be activated by microwave electromagnetic fields.…”