Synergically regulated silver species and surface oxygen on manganese oxide for promoted activity of formaldehyde oxidation

Formaldehyde (HCHO) is a common indoor pollutant that is detrimental to human health. Its efficient removal has become an urgent demand to reduce the public health risk. In this work, Ag-MnOx-based catalysts were prepared and activated under different atmosphere (i.e., air, hydrogen (H2) and carbon monoxide (CO)) for efficient oxidation of HCHO. The catalyst activated with CO (Ag/Mn-CO) displayed the highest activity among the tested samples with 90% conversion at 100°C under a gas space velocity of 75,000 mL/(gcat·hr). Complementary characterizations demonstrate that CO reduction treatment resulted in synergically regulated content of surface oxygen on support to adsorb/activate HCHO and size of Ag particle to dissociate oxygen to oxidize the adsorbed HCHO. In contrast, other catalysts lack for either abundant surface oxygen species or metallic silver with the appropriate particle size, so that the integrate activity is limited by one specific reaction step. This study contributes to elucidating the mechanisms regulating the oxidation activity of Ag-based catalysts.