Highly effective and energy-saving adsorption-microwave catalytic decomposition of NO with novel high-adsorption-capacity adsorbent in a two-stage fixed-bed reactor

It is a great challenge to achieve high efficiency and low energy consumption denitrification without adding reducing agent at low temperature. Herein, we developed MgCo2O4-BaCO3/AC carbon-based composites as novel and cheap adsorbents with high adsorption capacity to fill the first section of two-stage fixed-bed reactor to form adsorption bed, and MgCo2O4-40%BaCO3 as catalyst was filled in the second section as catalyst bed. Significantly, under the condition of excess O2, the adsorption capacity of 20%MC-0.5Ba/AC for NO was as high as 40.2 mg/g, and the conversion of adsorbed NO was as high as 99.7% under microwave irradiation at 250 °C. The denitrification efficiency of the two-stage fixed bed reactor was much higher than that of the one-stage fixed bed reactor. The energy efficiency of adsorption-decomposition method was 14 times higher than that of direct decomposition method. Interestingly, the activated carbon was not consumed during the whole reaction process, so no secondary pollution such as CO and CO2 was produced. More importantly, despite the presence of SO2, CO2 or H2O in the inlet gas, 20%MC-0.5Ba/AC still showed excellent adsorption capacity for NO, and the absorbed NO could be successfully decomposed, demonstrating excellent resistance to SO2, CO2 and H2O. This work presents a new route for denitrification technology with high efficiency, low energy consumption and no secondary pollution, and provides guidance for rational design of adsorbents with high adsorption capacity for NO.