Low-temperature NO decomposition through microwave catalysis on BaMnO3-based catalysts under excess oxygen: Effect of A-site substitution by Ca, K and La

•NO conversion and N2 selectivity is 99.7% and 99.9% for Ba0.8K0.2MnO3 in the MCRM.•Ea′ of BaMnO3 and Ba0.8A0.2MnO3 (ACa, K, La) are as low as 14.7-41.6 KJ/mol.•Catalytic activity in the MCRM is much higher than that in the CRM.•The effect of Ca, K and La substitution is different in these two reaction modes.

The low-temperature NO decomposition with high efficiency remains a grand challenge. Herein, we report an attractive approach for the low-temperature NO decomposition by microwave catalysis over BaMnO3 and substituted Ba0.8A0.2MnO3 (ACa, K, La) catalysts. Importantly, impressively high NO conversion and N2 selectivity with 99.9% and 99.9%, respectively, were achieved over Ba0.8K0.2MnO3 catalyst at 250 °C. Comparatively, under identical conditions in the conventional reaction mode, the highest NO conversion and N2 yield are respectively only 45.4% and 28.7% for Ba0.8K0.2MnO3 at 650 °C. Unexpectedly, the effect of Ca, K and La substitution is different in these two reaction modes. The catalysts were characterized by H2-TPR, O2-TPD, and microwave absorbing properties to illustrate possible reasons causing such obvious differences in catalytic performance. The apparent activation energies for BaMnO3, Ba0.8Ca0.2MnO3, Ba0.8K0.2MnO3 and Ba0.8La0.2MnO3 catalysts under microwave irradiation drop down to as low as 33.4, 41.6, 14.7 and 18.2 kJ/mol, separately, suggesting a significant microwave catalytic effect.

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