Formaldehyde Adsorption and Degradation at Room Temperature Boosted by Increasing the Specific Surface Area and Surface-Active Oxygen Content of Manganese Oxides

Abstract

Preparation of manganese oxides with both excellent adsorption and catalytic activity for formaldehyde (HCHO) removal at room temperature remains challenging. In this work, the reaction between sodium thiosulfate and potassium permanganate was used to obtain MnO x -S with a mesoporous structure, which was subsequently treated with sulfuric acid to obtain MnO x -S-A. With MnO x -S-A, under static test conditions, approximately 1 ppm (volume concentration) of HCHO was completely removed from a 216 L closed vessel in 1.25 h, and 100% removal was still achieved in 2.5 h after 5 cycles. In the dynamic test condition of 150 L/(g cat h), MnO x -S-A consistently removed more than 95% of formaldehyde in 9 h. The excellent activity and stability of MnO x -S-A at room temperature can be attributed to its abundance of surface-active oxygen and its high specific surface area (273 m 2 /g). This work provides new ideas to further improve the adsorption and catalytic activity of manganese oxides.