Catalytic formaldehyde removal by storage-oxidation cycling process over supported silver catalysts

Catalytic removal of indoor HCHO was proposed to proceed in a storage-oxidation cycling process. Two kinds of supported silver catalysts, namely Ag/HZSM-5 and Ag-MnOx-CeO2. were investigated as catalysts for this cycling process. Due to the highly dispersed silver clusters formed and its good redox properties, the Ag-MnOx-CeO2 catalyst showed better HCHO oxidation properties in both the storage phase (HCHO partial oxidation to HCOO- at room temperature) and oxidation-regeneration phase (total oxidation of the formates into CO2 and H2O at elevated temperatures). The presence of H2O (RH = 50%, 25 degrees C) was found to enhance the HCHO storage capacity for Ag-MnOx-CeO2 catalyst, while competitive adsorption of HCHO with H2O was observed over Ag/HZ catalyst. The results of DRIFTS indicate that the partial oxidation of HCHO into HCOO- is accelerated by the presence of H2O over the Ag-MnOx-CeO2 catalyst. In addition, the catalyst saturated with HCHO can be in situ regenerated without production of secondary pollutants and can be used repeatly. It is suggested that this is a promising approach for indoor HCHO elimination. (C) 2012 Elsevier B.V. All rights reserved.