Advances of manganese-oxides-based catalysts for indoor formaldehyde removal

Formaldehyde (HCHO) has been identified as one of the most common indoor pollutions nowadays. Manganese oxides (MnOx) are considered to be a promising catalytic material used in indoor HCHO oxidation removal due to their high catalytic activity, low-cost, and environmentally friendly. In this paper, the progress in developing MnOx-based catalysts for HCHO removal is comprehensively reviewed for exploring the mechanisms of catalytic oxidation and catalytic deactivation. The catalytic oxidation mechanisms based on three typical theory models (Mars-van-Krevelen, Eley-Rideal and Langmuir–Hinshelwood) are discussed and summarized. Furthermore, the research status of catalytic deactivation, catalysts’ regeneration and integrated application of MnOx-based catalysts for indoor HCHO removal are detailed in the review. Finally, the technical challenges in developing MnOx-based catalysts for indoor HCHO removal are analyzed and the possible research direction is also proposed for overcoming the challenges toward practical application of such catalysts.