Utilizing flue gas as feedstock for CO 2 electro−reduction systems is a promising technology to address problems caused by excessive CO 2 emissions. However, the O 2 contained in the flue gas has a significant adverse effect on the CO 2 reduction. Herein, a facile strategy was proposed to suppress the influence of O 2 by constructing a CO 2 −enriched region. N−doping was demonstrated to be an efficient way to enhance CO 2 adsorption selectivity over O 2 on activated carbon. The N−doped activated carbon achieved 3.7 times increase in CO 2 adsorption selectivity over O 2 than that before modification under simulated flue gas atmosphere (75 %N 2 + 15 %CO 2 + 10 %O 2 ). The distinction in adsorption mechanism between CO 2 and O 2 was revealed by quantum chemistry study. The increased polarity of the carbon materials favored CO 2 adsorption and had less impact on O 2 adsorption. The electrostatic interaction between CO 2 and carbon material was demonstrated to be enhanced after the introduction of pyridinic N and pyrrolic N, which led to an improvement in the CO 2 adsorption capacity. The dispersion interaction, which fully regulated O 2 adsorption, was weakened due to the deviation of the O 2 adsorption position. This study provided a reference for the subsequent development of CO 2 selective adsorption materials.
Selective catalytic reduction of NO using CO (CO-SCR) is a promising technology for the purification of NO in the flue gas. However, the presence of O 2 significantly inhibits the activity of the CO-SCR catalyst. Herein, we synthesize a hollow Mn-doped CeO 2 @Co 3 O 4 catalyst (Mn-CeO 2 @Co 3 O 4 ), which achieved 82% NO conversion, 100% CO conversion, and 78% N 2 selectivity under 5 vol% O 2 at 200 °C, superior to those of CeO 2 @Co 3 O 4 and Co 3 O 4 @CeO 2 catalysts. The characterization results indicate that the strong electronic interaction at the heterointerfaces between Co 3 O 4 and CeO 2 plays a crucial role in promoting selective adsorption of NO. Furthermore, the Mn doping into the Co 3 O 4 lattice of the catalyst facilitates the conversion of N 2 O intermediates, thereby enhancing the overall activity. This research provides a new strategy for the design and synthesis of CO-SCR catalysts.
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