Highly active copper-intercalated weakly crystallized δ-MnO2 for low-temperature oxidation of CO in dry and humid air
Hao Zhang , Huinan Li , Pengyi Zhang , Tingxia Hu , Xianjie Wang
Front. Environ. Sci. Eng. ›› 2024, Vol. 18 ›› Issue (5) : 62
Highly active copper-intercalated weakly crystallized δ-MnO2 for low-temperature oxidation of CO in dry and humid air
● Copper intercalated weakly crystallized δ-MnO2 was synthesized via one-pot process. ● Intercalated copper ions greatly enhanced the adsorption of CO. ● MnO2-150Cu achieved a 100% conversion of CO even at −10 °C under dry air. ● MnO2-150Cu exhibited a high CO oxidation capacity in an inert atmosphere at 30 °C. ● MnO2-150Cu maintained a 100% conversion of CO for 35 h at 70 °C in 1.3% moisture air.
Copper intercalated birnessite MnO2 (δ-MnO2) with weak crystallinity and high specific surface area (421 m2/g) was synthesized by a one-pot redox method and investigated for low-temperature CO oxidation. The molar ratio of Cu/Mn was as high as 0.37, which greatly weakened the Mn-O bond and created a lot of low-temperature active oxygen species. In situ DRIFTS revealed strong bonding of copper ions with CO. As-synthesized MnO2-150Cu achieved 100% conversion of 250 ppm CO in normal air (3.1 ppm H2O) even at −10 °C under the weight-hourly space velocity (WHSV) of 150 L/(g·h). In addition, it showed high oxygen storage capacity to oxidize CO in inert atmosphere. Though the concurrent moisture in air significantly inhibited CO adsorption and its conversion at ambient temperature, MnO2-150Cu could stably convert CO in 1.3% moisture air at 70 °C owing to its great low-temperature activity and reduced competitive adsorption of water with increased temperature. This study discovers the excellent low-temperature activity of weakly crystallized δ-MnO2 induced by high content intercalated copper ions.
CO oxidation / Birnessite / Interlayer copper / Low-temperature / Oxygen storage capacity
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Higher Education Press 2024
Supplementary files
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