US EPA

5931653 

Journal Article 

Potassium-modulated delta-MnO2 as robust catalysts for formaldehyde oxidation at room temperature 

Ji, J; Lu, XL; Chen, C; He, M; Huang, HB 

2020 

Yes 

Applied Catalysis B: Environmental
ISSN: 0926-3373 

260 

118210 

English 

10.1016/j.apcatb.2019.118210 

WOS:000496894300066 

Engineering MnO2 with rich surface active oxygen species is critical to effectively eliminate formaldehyde (HCHO) under mild conditions. Herein, we introduced a facile redox method to fabricate a series of delta-MnO2 samples by varying the concentration of K+, which efficiently modulated the layer size, morphology, crystallinity, redox properties, and thus the surface active oxygen species of the obtained delta-MnO2. The medium potassium concentration led to the optimized Mn-O bond strength, the abundant surface active oxygen species, and the complete conversion of ca. 22 ppm HCHO at 30 degrees C under a weight hourly space velocity (WHSV) of 200,000 mL/(g(cat) h). Surface adsorbed oxygen species (e.g., O-2(-) and O-) and surface hydroxyl groups, were suggested to oxidize HCHO into intermediates (i.e., DOM, formate, and carbonate species). Water was critical for further transforming the intermediates into CO2. A Langmuir-Hinshelwood (LH) mechanism was proposed involving in the whole oxidation process. 

formaldehyde oxidation; poor crystalline delta-MnO2; potassium; surface active oxygen species; catalytic oxidation mechanism