Room temperature oxidation of gaseous formaldehyde over silver-doped manganese oxide catalyst

A wide amount of existing building materials and consumables contains formaldehyde (HCHO) that may be released as a gas even after installation. The produced gas may concentrate in housing and offices, leading to a long-term exposure of the occupants. Living in such an environment, even at low concentrations less than 0.5 ppm, may lead to carcinogenic effects and damages of the human central nervous system. As a consequence, the development of methods that oxidize and neutralize the formaldehyde at ambient temperature is welcome. The catalytic oxidation method at ambient temperature is preferred over other available techniques due to its ease of operation and high efficiency. In this work, different weight percentages, ranging from 1 up to 5%, of silver-doped manganese oxides (Ag/MnOx) were synthesized by a co-precipitation process followed by a calcination at 450 °C for 4 h. The XRD and BET analysis results show that the sample at 4% wt of Ag doped in the MnOx matrix exhibit highest crystallinity, surface area and highest dispersion values, very near to theoretical ones. The removal performance of HCHO was tested in a silicon wool bed continuous flow reactor characterized by an inner diameter of 4 mm and a length of 12.5 cm. At ambient temperature a removal efficiency and an amount of produced CO2 of 94% and 66%, respectively.